Symposium B Poster Session

Thursday, May 1, 2014 5:00 PM in Room Town & Country and San Diego

BP-2 Investigation of Adhesion and Corrosion Properties of CrAlYN/CrY Multilayer Coatings Deposited by Unbalanced Magnetron Sputtering
Morteza Tahmasebian Myandoab, Ihsan Efeoglu, Kadri Ezirmik, Ersin Arslan, Yasar Totik, EbruEmine Sukuroglu (Atatürk University, Turkey); Özlem Baran (Erzincan University, Turkey)
Transition metal nitride coatings such as CrN and CrAlN are known for their excellent Tribological and corrosion properties. Adding yttrium to these coatings improves their oxidation resistance. Furthermore, CrAlYN coatings due to their outstanding mechanical properties and thermal stability are highly valued for various industrial applications. In the present study, CrAlYN/CrY multilayer films were deposited by unbalanced magnetron sputtering (UBMS) from two CrY and one Al targets. The structural properties of the coatings were analyzed by electron microscopy, X-Ray diffraction and energy dispersive spectrometry. Additionally, the adhesion properties of the coatings were evaluated via scratch tests. Corrosion properties of the coatings were investigated by potentiostat test unit.
BP-3 DLAg and DLSiO Films with Good Tribological and Corrosion Resistance Properties for Aerospace Applications
Fernanda Lucas (Universidade do Vale do Paraíba, Brazil); Polyana Radi, Sara Fissmer (Technologic Institute of Aeronautics, Brazil); Priscila Leite, Rodrigo Pessoa, Homero Maciel, Lúcia Vieira Santos (Universidade do Vale do Paraíba, Brazil)

About solid lubricant development for aerospace application, three issues are crucial to obtain good tribological performance: wear resistance related with fretting during the satellite launch, high adhesion on the substrate, and high lubricant life associated with low friction coefficient environment (less than 0.3) and its resistance in atomic oxygen.

This paper presents comparative studies on amorphous diamond-like carbon (DLC) containing silver nanoparticles (DLAg) and Silicon oxide bonds (DLSiO) obtained via automated plasma enhanced chemical vapor deposition (PECVD) using methane, silver cage, and Hexamethyldisiloxane, as carbon, silver, and silicon precursors. The films were produced in order to obtain repeatability and traceability on tribological behavior for aerospace use associated with high corrosion resistance in atomic oxygen atmosphere.

The DLAg and DLSiO were deposited on titanium alloy surfaces and the growth parameters (work pressure, temperature, discharge power, and duty cycle) were controlled to guarantee repeatability and traceability of the films. Friction, wear and adhesion tests were run out in a Bruker Tribometer. The corrosion resistance was evaluated by atomic plasma oxygen etching and chemical structure degradation was analyzed with Raman spectra.

BP-4 Production and Characterization of Niobium Carbide Coatings on Gray Cast Iron by Termorreactive Difussion/Deposition
ArielAugusto Amaya A., OscarEdwin Piamba Tulcan, Jhon Olaya (Universidad Nacional de Colombia Bogotá, Colombia)

Production research for industrial coatings from thermochemical processes plays an important role in materials science. Thermoreactive Diffusion deposition technique (TRD), to obtain homogeneous, continuous and resilient coatings for a simple procedures at cost.

The coating was deposited in gray iron pearlitic matrix with randomly distributed lamellar graphite and 3.5% total carbon percentage. The process was carried out in a salt bath of molten borax at 940 °C for 2 to 5 hours. Ferro-niobium is used as the carbide-forming element and aluminum as the reducing agent.

The coatings obtained were characterized by scanning electron microscopy (SEM), Auger Electron Spectroscopy (AES), and X-ray diffraction (XRD). SEM showed compact, continuous, homogeneous coatings and smooth interface. From XRD was observed with a composition consisting of NbC, with preferential orientation in the (111) and (200). From AES was verified the presence of Niobium at 167.7 eV and carbon at 266.8 eV mainly. It also determined a significant increase in the Vickers hardness of 510 to 2198± 97 Vickers for casting at niobium carbide coating. Finally, it was found that the corrosion resistance and adhesion to the substrate increases, when evaluated by the technique of potenciodimnamic polarization and resistance for Scratch respectively.
BP-5 Radiation Exposed Hydrogenated Amorphous Carbon Films: Microstructure and Wettability
Kelaine Hofelmann, Márcio Partichelli, Ricardo Zanon (Universidade do Estado de Santa Catarina, Brazil); CarlosAlberto Achete (InMetro - Instituto Nacional de Metrologia, Brazil); Julio Pureza (Universidade do Estado de Santa Catarina, Brazil); Mônica Lacerda (Universidade Federal do Rio de Janeiro, Brazil)

Microstructure and wetting character of radiation exposed hydrogenated amorphous carbon (a-C:H) films were evaluated by Raman spectroscopy, by measuring their contact angle with water droplets and by calculating their surface tension. a-C:H films were deposited by plasma enhanced chemical vapor deposition (PECVD) at room temperature from pure acetylene (C2H2) gas used as carbon and hydrogen atoms precursor. Samples were exposed to ultraviolet and gamma radiation and to alpha particles. They were analyzed as a function of the deposition pressure that ranged between 13 Pa and 400 Pa. Their microstructures were analyzed at two Raman excitation wavelengths, 514.5 nm and 1064 nm. Results show that the a-C:H structure is formed by a combination of sp and sp2 carbon-carbon bonds and sp3 carbon-hydrogen bonds. Typical D and G bands at both excitation frequencies are presented in all spectroscopy data and different features could be observed depending on the Raman excitation energy. At green excitation an intermediate band between D and G bands and close to 1500 cm-1 can be accessed. It is associated to sp3 carbon-hydrogen bonds. At 1064 nm a band close to 1850 cm-1 is an evidence of the presence of sp carbon bonds. As-deposited a‑C:H film wetting character results show a very dramatic change in the contact angle between the surface and deionized water droplets. Samples deposited at C2H2 pressure as low as 26 Pa are hydrophilic, while those deposited at 400 Pa are super hydrophobic with contact angle above 160o. Post deposition radiation changes the surface tension of all samples; although modifications are dependent on the radiation energy. It changes the surface structure of the samples, but the bulk microstructure remains the same.

BP-6 Reactive and Non-reactive Deposition of Al-Cr-N Coatings using Metallic, Intermetallic, and Ceramic Target Material
Corinna Sabitzer (Vienna University of Technology, Austria); Szilárd Kolozsvári (Plansee Composite Materials GmbH, Germany); Mirjam Arndt, Richard Rachbauer (Oerlikon Balzers Coating AG, Liechtenstein); Jörg Paulitsch, Paul Heinz Mayrhofer (Vienna University of Technology, Austria)

Physical Vapour Deposition techniques, like magnetron sputtering or arc evaporation, are highly valued for industrial applications to synthesize hard protective coatings with superior performance. Generally, powder metallurgically prepared targets composed of e.g. metallic Al and Cr particles are used in a reactive nitrogen atmosphere to deposit AlxCr1-xN. For both deposition processes, the influence of various deposition parameters ─ like partial pressure, gas mixture, or temperature ─ on the coating performance is well investigated, but only little information is available concerning the impact of the target material itself. Therefore specially developed powder metallurgical prepared targets, with a comparable Al/Cr ratio, consisting of metallic Al and Cr, intermetallic Al8Cr5, and ceramic AlN and CrN powder were used to deposit Al0.7Cr0.3N films. Furthermore, due to the possibility to use a ceramic target material comparative investigations on the influence of a reactive (Ar/N2 atmosphere) and non-reactive (Ar atmosphere) deposition were carried out. Detailed analysis of the resulting microstructure, mechanical properties as well as thermal stability and oxidation resistance indicate a strong influence of the different targets used. Changing from the metallic target materials to the ceramic-like target and from reactive to a non-reactive deposition process the preferred orientation of the AlxCr1-xN film can be altered from preferred (111) to (200). Further on, fracture cross sections indicate a more nano-crystalline-like morphology as well as a significantly increase in deposition rate from values between 11 and 16 nm/min to 23 nm/min, respectively, when using non-reactive deposition to prepare AlxCr1-xN. Hardness evaluations demonstrate that values around 25 GPa can be obtained when using the nitride target material, which is twice as high as for reactively deposited coatings from standard metallic Al/Cr targets using similar process parameters. Also, investigations on the thermal stability, especially with respect to the onset of Cr-N dissociation, indicate a clear shift of decomposition to higher temperatures for coatings prepared from optimized target materials.

BP-7 Impact of Point Defects on Stability of (Al1-xCrx)2O3 Phases from First Principles
Christian Koller (Vienna University of Technology, Austria); Jürgen Ramm (Oerlikon Balzers Coating AG, Liechtenstein); Peter Polcik (Plansee Composite Materials GmbH, Germany); David Holec (Montanuniversität Leoben, Austria); Jörg Paulitsch, Paul Heinz Mayrhofer (Vienna University of Technology, Austria)

A central subject of current protective coating development is the phase formation in low temperature physical vapour deposited, PVD, (Al1-xCrx)2O3 coatings. Experimental results have shown that magnetron sputtered or arc evaporated coatings synthesised at temperatures as low as 500 °C usually crystallise in an amorphous or metastable face centred cubic based phases, like the defect-spinel γ- or the B1-type. This is however in contradiction to ab initio phase stability predictions, which suggest the desired and industrially important corundum type solid solution α-(AlxCr1-x)2O3 to have lower energy of formation, thus being the stable phase and preferentially formed.

Within our investigations of three phases (corundum α, defect-spinel γ, and B1-like fcc) across all Al compositions, x, of (AlxCr1-x)2O3 we find that the α solid solution is more sensitive to randomly generated defects than the γ-type and B1-type. We propose that these findings in addition to exceptionally high surface energies for certain terminations of the corundum structure can explain the favoured formation of γ- and B1-(AlxCr1-x)2O3 during low temperature PVD processes, which generally lead to high defect densities and small crystallite sizes.

BP-8 Synthesis and Characterization of Thin Films Doped with Cobalt by MOCVD
NestorEfren Mendez Lozano, LuisMiguel Apatiga Castro (Universidad Nacional Autonoma de Mexico, Mexico)

In this work thin films doped with cobalt were prepared by Metal – Organic Chemical Vapor deposition. Photocatalytic activity of TiO2 particles has been investigated extensively because of their strong oxidizing power, high chemical durability, and nontoxicity. It is well known that nanometer-sized anatase particles with high crystallinity have a high photocatalytic activity [1]. However, the absorption wavelength of anatase (λ≤385 nm) does not fit with the solar spectrum; the solar energy above 3.0 eV (λ≤410 nm) is less than 5%.

In this study, thin films of TiO2 doped with cobalt deposited on glass and silicon substrates were synthesized using the technique of vapor phase chemical deposition from metal-organic precursors such as titanium isopropoxide and cobalt acetylacetonate , the films were doped with different concentrations of cobalt 2 %, 4% 6 %, 8% and 10 %.

With the synthesis and characterization of our material is achieving a better understanding of the synthesis methodology also improved to some extent on the different physical and chemical properties of the material. The crystal structure of all prepared samples were characterized by X-ray diffraction to confirm the existence of anatase phase of TiO2; Raman spectroscopy results were complemented observing the characteristic vibrational modes of TiO2 in its anatase phase.

The morphology and growth of the films was characterized by electronic microscopy (SEM) observed a flower-like growth in all samples. Finally the optical characterization of the samples was performed by UV-Vis spectroscopy obtained with these results a value of bandwidth allowed for each sample obtained and the relationship between the amount of impurities in each sample and its improvement in their electronic properties.

References

[1] Tada, H., and Tanaka, M., Langmuir 13, 360 (1997) Anpo, M., Ichihashi, Y., Takeuchi, M., and Yamashita, H., Res. Chem.Intermed. 24, 151 (1998).

BP-9 Microstructure, Mechanical and Electrochemical Properties of Vanadium-Niobium Rich Carbide Layers Grown by TRD
Fabio Castillejo (Universidad Santo Tomás Bogotá, Colombia); Jhon Olaya, José Alfonso (Universidad Nacional de Colombia Bogotá, Colombia)

Nb-V complex carbide coatings were produced onto AISI D2 steel by the thermo-reactive diffusion (TRD) process to improve the surface hardness and corrosion resistance of this tool steel. The carbide coating treatment was performed using molten borax added with ferroniobium, ferrochrome and aluminum at temperatures of 1223, 1293 and 1363 K during 2, 3, 4 and 5 h. The coating layers were characterized by optical and Scanning Electron Microscopy Microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and X-ray fluorescence spectrometry (XRF). The coating growth rates were studied, and a kinetically model of the layer thickness as a function of the treatment time and temperature was established. The hardness of the coating was measured by nanoindentation and its resistance to corrosion was evaluated with electrochemical tests of potentiodynamic polarization. The carbide layers produced a homogeneous thickness as well as an improved hardness and corrosion resistance as compared to the uncoated steel.

BP-10 Electrochemical and Tribological Properties of Cr-Nb Carbides produced by TRD Process.
Fabío Alfonso (Universidad Santo Tomas, Colombia); Jhon Olaya, Oscar Piamba (Universidad Nacional de Colombia Bogotá, Colombia)

Niobium-Chromium carbide coatings were deposited by thermo-reactive diffusion (TRD) deposition technique on three different tool steels (AISI D2, 1045 and H13). The carbides were obtained using salt baths composed of molten borax, aluminum, and ferro-niobium or ferro-chromium. All steels were treated through TRD process performed at 1020 °C for 4 hours. The thickness and morphology of the coatings were characterized by optical and Scanning Electron Microscopy (SEM) and the crystalline structure was studied through X-ray diffraction (XRD). Chemical composition was evaluated by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Hardness of the coatings was measured by nanoindentation, and its wear resistance was studied by bole on disk test. The rate of corrosion was assessed with potentiodynamic polarization and the corrosion resistance was evaluated via electrochemical impedance spectroscopy (EIS) tests. The XRD results confirmed the formation of NbC and CrxCy phases in all carbides. SEM results shows good homogeneity in the coatings thickness, and nanoindentation results showed that the coatings have higher hardness in comparison to the uncoated steel. XPS results indicated that the coatings are formed by carbides of chromium and niobium and the corrosion resistance is higher compared to the uncoated steel.

BP-12 Corrosion Protection Coatings with Atomic Layer Deposition
Emma Härkönen (University of Helsinki, Finland); Sanna Tervakangas, Jukka Kolehmainen (DIARC-Technology Inc., Finland); Ivan Kolev (Hauzer Techno Coating B.V., The Netherlands); Belén Díaz, Jolanta Swiatowska, Vincent Maurice, Antoine Seyeux, Philippe Marcus (Chimie ParisTech (ENSCP), France); Martin Fenker (FEM Forschungsinstitut Edelmetalle & Metallchemie, Germany); Lajos Tóth, György Rádnoczi (Research Centre for Natural Sciences HAS, Hungary); Marko Vehkamäki, Mikko Ritala (University of Helsinki, Finland)

Atomic layer deposition (ALD) is a chemical vapor deposition (CVD) based method for growing thin films with high precision.1 The growth proceeds through alternating and saturating surface reactions of two or more gaseous precursors. Because the precursors are pulsed in the reaction chamber alternately and separated by inert gas purging, excellent conformality even on high aspect ratio structures can be achieved. The films grow one atomic layer per cycle and thus both the thickness and composition can be controlled down to nm level. ALD thin films are known to have low defect density already at <10 nm thicknesses.

In the present work three types of ALD corrosion protection coating systems were studied on low alloy steel. Firstly, single 50 nm ALD coatings combining the excellent barrier properties of Al2O3 and chemical stability of Ta2O5 were considered. The aim was to optimize the coating structure for best sealing properties and durability. Secondly, a 10 nm filtered cathodic arc deposited (FCAD) film was grown under the optimized 50 nm ALD coatings. The FCAD layer homogenized the steel surface for a more ideal ALD growth, which led to improved protective properties. Thirdly, the conformality of ALD was utilized in sealing pinhole defects in physical vapor deposited (PVD) CrN coatings. The corrosion protection properties of the coatings were studied with electrochemical measurements (LSV and EIS) and neutral salt spray (NSS) testing. Additionally, the morphology and composition of the coatings were analyzed to gain insight into the protection mechanism. The ALD coatings had excellent barrier properties, reaching a decrease of three orders of magnitude in the corrosion current density of the steel. The long-term durability of the single ALD coatings was found to be insufficient but could be improved with the FCAD sublayers. Moreover, the NSS durability of CrN coated steel could be increased from 2 to 168 hours with ALD sealing.

[1] V. Miikkulainen, M. Leskelä, M. Ritala and R. Puurunen, J. Appl. Phys. 113 (2013) 021301

BP-14 Investigation of Hysteresis Effect and Influence of Bias Voltage during Deposition of HPPMS Aluminum Oxide Coatings
Kirsten Bobzin, Nazlim Bagcivan, RicardoHenrique Brugnara, Serhan Basturk (RWTH Aachen University, Germany)

Crystalline PVD alumina coatings offer a high potential for application as protective coating material on cutting tools due to their high hot hardness, high chemical inertness, high thermal stability and good wear resistance. Especially over the last decade the High Power Pulsed Magnetron Sputtering (HPPMS) technology has gained a growing interest. This technology offers possibilities to improve the coating properties such as microstructure and mechanical properties.

In the first part of this work the hysteresis behavior of Al target sputtered in a HPPMS discharge and a Kr/Ar/O2 mixture was investigated for various HPPMS pulse lengths (30, 50, 100, 200 μs) at constant pulse frequency and average power in an industrial scale unit. Cathode current and voltage were recorded for the different pulse lengths. In a second step, aluminum oxide coatings were deposited on cemented carbide substrates at a constant pulse length of 50 μs and various bias voltages (-100, -200 and -250 V). The coating thickness and morphology are determined using SEM (Scanning Electron Microscopy). Hardness and Young’s modulus were measured using nanoindentation. Phase composition was investigated by using XRD (X-ray Diffraction). Decreasing of pulse length from 200 to 30 μs at constant average power leads to a considerable increase of cathode current from 76 A to 468 A, respectively. It could be observed that the peak current has a strong influence on the amount of maximum allowable oxygen flow in the reactive process. Longer pulse lengths and so lower peak current allow a higher oxygen flow in the coating process compared to short pulses. The characterization of deposited coatings shows that at higher bias values a dense fine grained crystalline morphology is observed. However, a decrease of the deposition rate was observed with increasing bias from -100 V (1,26 μm/h) to -250 V (0,77 μm/h). Regarding the phase composition, peaks of crystalline γ-Al2O3 were detected for all deposited HPPMS aluminum oxide coatings.

Keywords: PVD, HPPMS, HiPIMS, Al2O3, aluminum oxide

BP-15 Effect of Composition on Fracture Toughness of TiZrN Hard Coatings
Yu-Fu Chen, Jia-Hong Huang (National Tsing Hua University, Taiwan)

Fracture toughness is one of the most important mechanical properties for both bulk and thin film materials. For bulk materials, fracture toughness can be easily measured through ASTM standard procedures. In contrast, fracture toughness measurement of thin films is still problematic. Many kinds of testing methods have been developed and used to evaluate the fracture toughness of thin films. Recently, our group proposed an energy-based method without using the external stress, but employed the residual stress as the stress source to induce cracking. The proposed method has been applied on both TiN and ZrN hard coatings, and the results showed that the fracture toughness of random-textured TiN hard coating was 16.5 that was a reasonable value compared with previous literatures. On the other hand, the results of ZrN hard coatings showed an anisotropic variation with crystal orientation. In this research, TiZrN ternary nitride film was chosen for a model material because TiZrN is a single phase material when deposited at temperatures lower than 500°C. According to Griffith criterion, fracture toughness is the release of elastic energy that can create two new surfaces of a crack for brittle materials, which is associated with atomic bonding energy of the fracture surface. In TiZrN thin film, the bonding energy may change with Ti/Zr ratio, and thus composition may strongly affect the fracture toughness. The objective of this study was to investigate the effect of composition on the fracture toughness of TiZrN hard coatings. TiZrN coatings with different Ti/Zr ratio were prepared by unbalanced magnetron sputtering. Following our previous testing method, residual stress was used as the stress source for the toughness measurement, which could be measured by the laser curvature method. For the proposed energy-based method, the average storage energy (Gs) was evaluated from the residual stress before crack initiation, and then the fracture toughness (Gc) of the TiZrN coatings can be obtained from Gs.

Keyword: Fracture toughness, TiZrN, residual stress

BP-16 Comparison of Corrosion Resistance of N-doped ZrO2 Thin Films Deposited by HCD-IP and Grown by Heat Treating ZrN Thin Films in Vacuum
Sun-An Chou, Jia-Hong Huang (National Tsing Hua University, Taiwan)

ZrO2 is commonly used as a protective coating for metal substrates owing to its excellent corrosion resistance, while ZrO2 coating is difficult to be deposited on the stainless steel because of the wettability problem. The purpose of this research was to overcome the wetting issue by producing ZrO2 coatings on the stainless steel using ion plating or by heat treating ZrN coatings in vacuum. In this study, we used two approaches to deposit ZrO2 films on stainless steel. One approach is to directly deposit ZrO2 on stainless steel substrate using hollow cathode discharge ion-plating (HCD-IP) method, where the HCD-IP provided high ionization rate and solved the wetting issue. The other one was to deposit ZrN films on the stainless steel substrate, and then oxidize the ZrN films by heat treated the specimens in vacuum at 1000°C converting part of the ZrN to ZrO2. The growth mechanisms of ZrO2 are different in these two methods. In the former method, the ZrO2 film grows in the way of the columnar grain growth from bottom-up direction. However, in the latter method, the ZrO2 film grows inside the ZrN film from top-down direction and the ZrO2 layer becomes nano-granular structure in the vacuum heat treatment. The 500-hr salt spray tests indicated that the ZrO2 coatings produced by both methods shows excellent corrosion resistance. The corrosion resistance of the ZrO2 films was further evaluated by AC impedance and potentiodynamic polarization scan. The AC impedance wa s undergone in the 1N H2SO4 and potentiodynamic polarization scan was carried out in 5% NaCl and in 1N H2SO4.

BP-17 Effect of Processing Parameters on Wear Resistance and Mechanical Properties of Thick TiN Film on D2 Steel Deposited by Unbalanced Magnetron Sputtering
Chia-I Chiu, Jia-Hong Huang (National Tsing Hua University, Taiwan)

Due to their excellent mechanical properties, t itanium nitride (TiN) coatings have been widely utilized in tool industry as wear resistant and protective coatings. The usage of hard coatings can not only protect the substrate, but also significantly extend the service life of the products. The major requirements of wear resistant coatings are high hardness with substantial thickness, a least a few mm. However, with the increment of film thickness, the internal residual stress may accumulate, and lead to film spallation. The objective of this study was to deposit thick TiN coatings (> 5mm) on AISI D2 tool steel substrates without using Ti interlayer, and to investigate the influence of different processing parameters on wear resistance and mechanical properties of the coatings. TiN coatings were deposited on AISI D2 steel substrates using unbalanced magnetron sputtering at different deposition parameter s. The main controlling deposition parameter s to produce thick TiN coatings were the opening of gate valve between turbomolecular pump (TP) and deposition chamber and the pumping speed of TP. The flux of argon and nitrogen was at a fixed ratio. X-ray diffraction (XRD) was used to determine the preferred orientation of the TiN films. The hardness of the TiN coatings was measured using nanoindentation. The residual stresses of the TiN coatings were determined by cos2α sin2ψ XRD and laser curvature method. The adhesion between the coating and substrate was evaluate d by scratch test. The influence of deposition parameter on wear resistance of the coatings was evaluated using pin-on-disk wear test. By adjusting deposition parameters, we could successfully produce thick TiN films on D2 steel with low residual stress and superior wear resistance. In addition, the deposition process consumed much less energy than traditional processes, and therefore the results will be useful for industrial appl ications.

Keyword: titanium nitride, AISI D2 tool steel, wear resistance, micrometer size

BP-18 Effect of Substrate Bias on Structure and Mechanical Properties of Synthesis of (Ti, Zr)N Hard Coatings by DC Unbalanced Magnetron Sputtering
Hsi-An Chen, Ge-Ping Yu (National Tsing Hua University, Taiwan)

Ternary TiZrN thin films were deposited by DC unbalanced magnetron sputtering from dual guns(Ti,Zr) targets onto Si (100) substrates. In this work, we investigate the effect of substrate bias on the structure and properties of ternary TiZrN thin films (exchanging bias from -20V to -100V). The substrate bias primarily affected the properties and structure containing hardness, preferred orientation, packing factor, etc. Consequently, substrate bias is a sensitive factor for process parameters of TiZrN coating. The crystal structure and preferred orientation of TiZrN films were characterized using X-ray diffraction (XRD). Experimental results indicate that the preferred orientation of TiZrN films is changed from (200) to (111) with increasing substrate bias. Zr adatoms are re-sputtered more easily than Ti adatoms during film growth. However, the experimental results show that Ti / Zr ratio did not vary obviously with different substrate bias. The crystallinity and packing factor, which associated with hardness, were enhanced by increasing substrate bias. TiZrN films had maximum hardness 32GPa as the bias voltage reached the critical value. Due to strengthening mechanism of the TiZrN are solid solution strengthening and grain boundary strengthening, the optimal solid solution strengthening effect(greatest inhomogeneous stain) can be obtained by controlling the ratio of Ti/Zr close to 1 for all the specimens. Both hardness and packing factor decreased as the bias voltage exceeded the critical value. Resistivity increased with increasing bias and with decreasing packing factor.

Keyword: Sputtering, Substrate bias, TiZrN
BP-19 Effect of Temperature on Exchange Bias of BiFeO3/FePt Bi-layer Films Epitaxial System Deposited by Radio-frequency Sputtering
Li-Chun Huang, Ge-Ping Yu (National Tsing Hua University, Taiwan)

The objective of the study is to investigate effects of temperature on BiFeO3(BFO)/FePt epitaxial bi-layers system structure. In this paper, we prepared the BFO (10 nm) / FePt (10 nm) thin films epitaxially grown on (111) SrTiO3 (STO) single crystal substrates and systemically study effect of deposition temperature of FePt. The formation of epitaxial films structure was confirmed from the x-ray diffraction and (00L) Bragg reflection of x-ray. A slight partial relaxation of out-of-plane strain in epitaxial systems was observed. Synchrotron radiation XRD results display c lear six fold symm etries and (111) FePt/BFO films by using (111 ) azimuthally sc an, unambiguously indicating that the present samples are epitaxially thin films. Large exchange bias of 150 – 360 Oe at room temperature were obtained for the epitaxial (111) FePt (10 nm)/BFO (10 nm) films at different growth temperatures (400 – 700 ºC). The exchange bias for the samples grown on (111) STO subs trate is high er than those of samples deposited on (100) STO substrate. An intuitive and reasonable explanation for this discrepancy is the surface spin configuration of BFO layer, because BFO (111) has an uncompensated surface and (001) has a compensated surface. With regard to temperature of FePt, there have exchange bias for the samples with FePt temperature below 600 ºC. As FePt temperature excesses the blocking temperature, the exchange bias decreases dramatically. The effect of surface roughness of BFO layers on exchange bias in the present samples was also investigated. In conclusion there has a large exchange bias on BFO/FePt bi-layers due to well epitaxial structure.

Keywords: epitaxial, BFO/FePt, excha nge bias

BP-20 Closed Drift Type Circular Ion Source
Jong-Kuk Kim, Ki-Taek Kim, Yong-Jin Kang, Do-Geun Kim, Seunghun Lee (Korea Institute of Materials Science, Korea)
In the past, closed drift type linear ion sources have been developed for many vacuum treatments. We investigated closed drift type circular (4 inch) ion source because the circular ion source is useful to treat small samples briefly. The circular ion source also uses ExB drifting electrons and accelerates ions near anode surface. In this work, the effect of electrode gaps on ion extraction was investigated. The B-field distributions at the various gaps were analyzed by using 3D magnetic field calculations. 2D particle-in-cell calculation was used to predict ionization and ion acceleration. And the discharge current and ion current were measured when the two gaps of cathode-cathode and anode-cathode is varied. Typical discharge voltage was 1~3 keV and the average ion energy was almost 40% of the discharge voltage. The ion energy distribution was measured by using a retarding field energy analyzer.
BP-22 Optical Properties Of Tetrahedral Amorphous Carbon Films And Their Potential For Lab-On-A- Chip
Katja Guenther (University of Applied Sciences Mittweida, Germany); Frank Sonntag (Fraunhofer IWS, Germany); Steffen Weißmantel (University of Applied Sciences Mittweida, Germany)

Several micrometer thick super-hard tetrahedral amorphous carbon (ta-C) films have been deposited by pulsed laser deposition (PLD) using an excimer laser (248 nm wavelength) onto polished tungsten carbide and silicon substrates.

The aim was to investigate the optical properties (e.g. the optical band-gap as well as the refractive and absorption index in the visible and near-infrared wavelength range) of these layers in dependence of the laser fluence on the target. It will be shown that the refractive index of 2 µm thick ta-C films varies between 2.3 and 2.8 at 632 nm wavelength in dependence of the sp³-content. Besides the absorption index is as low as 0.03 at the highest sp3 content of some 80 %.

The partial transparency of these ta-C layers in the visible range results in interference even at a film thickness up to 2 µm.

Furthermore, it will be shown that the ta-C films have low background fluorescence in the wavelength range of 380 - 750 nm, which may be used, as we are going to show, for optical and biotechnological applications.

One possible application is Lab-on-Chip (LOC). Thereby, the ultrasensitive detection of fluorescence markers and of dyes is one challenge in LOC applications. In order to increase the signal-to-noise-ratio, we developed a setup, which uses the specific optical properties of ta-C films produced by PLD. An integrated ta-C film based reflector combines the low background fluorescence, the low reflectivity at the excitation wavelength and the high reflectivity at the emission wavelength.

In this paper, we will show how we can improve the detection of fluorescence photons and with it the resolution of the fluorescence images by using ta-C films.

We will show that ta-C films, which are produced by PLD, have a high potential for optical applications.

BP-23 Raman Study on Structural Changes of DLC Films Deposited on Curved Surfaces
Junho Choi, Tetsuya Hatta, Takahisa Kato (The University of Tokyo, Japan)
Bipolar-type plasma based ion implantation and deposition (bipolar PBII&D) is a promising surface coating technique for complex-shaped target surfaces. In this study, diamond-like carbon (DLC) films were deposited on steel rods with various radii of curvatures using bipolar PBII&D and the plasma behavior in surrounding of the steel rods (i.e., flux and energy of incident ions and electrons) was calculated using Particle-In-Cell Monte Carlo Collision (PIC-MCC) Method. The positive and negative pulse voltages varied from +1.0 to +1.5 and from -1.0 to -5.0, respectively. The structure of DLC films was evaluated by Raman spectroscopy and the hardness of DLC films was measured using nanoindentation. It was found from Raman and nanoindentation measurements that the structures of DLC films coated on the rod-shaped surfaces are different from those of DLC films coated on the flat-shaped surfaces, which are affected by the flux and energy of incident ions and electrons.
BP-24 Effect of Amino Acid Additives on the Microstructure of Electrodeposited Nickel Films
Taichi Nagai, Kazunori Hodouchi, Hiroshi Matsubara (Nagaoka University of Technology, Japan)

20 kinds of amino acids were added to Ni electroplating bath in order to the effect on the characteristics of electroplated nickel films, i.e., surface morphology, film composition, crystal structure, and hardness.

Nickel films with higher hardness due to smaller crystalline size were obtained by the addition of basic amino acids, S-containing amino acids and certain aromatic amino acid.
BP-26 Mechanical Properties of TiAlSiN Coatings by Hybrid Process
JiHoon Yang, Jae-In Jeong, Min-A Song, Jae-Hun Jung (Research Institute of Industrial Science and Technology, Republic of Korea)
Titanium aluminum silicon nitride (TiAlSiN) has unique properties such as high hardness, wear resistance, and oxidation resistance at relatively high temperature. Synthesis methods for TiAlSiN coatings are cathodic arc deposition and reactive magnetron sputtering etc. In this report, cathodic arc and magnetron sputtering (hybrid process) have been used for deposition of TiAlSiN films. TiAlSiN films have been deposited on stainless steel, high speed steel, and tungsten carbide substrate. Ti-50at%Al arc target of 120 mm diameter and Si sputtering target of 6 inch diameter have been used. The mixture of Ar and N2 gas has been used for the deposition. Prior to the deposition, the substrate was cleaned by arc, which was created by only Ar gas, with -1000 V dc substrate bias. TiAlSiN coatings were carried out at R.T. and with -100 V dc substrate bias. TiAlSiN films have been investigated their morphology and mechanical properties. The hardness of the TiAlSiN film was ~34 GPa.
BP-27 Electrochemical Characteristics of Heterostructural Nanolayer Tantalum Nitride Coatings
Fan-Bean Wu, Kun-Yuan Liu (National United University, Taiwan)

Tantalum nitrides, TaN, were deposited by magnetron sputtering technique with sequential crystalline and amorphous layer stacking to form heterostructurally nanolayer films. The single component TaN layers with amorphous and crystalline phases could be controlled by N2/(Ar+N2) inlet gas ratio during fabrication. The amorphous TaN layer was formed under a N2/(Ar+N2) ratio over 0.25, while the TaN layer crystalized at a ratio lower than 0.10. Sharp and intact interfaces between amorphous and crystalline layers could be observed through detailed microstructure analysis. Electrochemical tests, including potentiodynamic scanning and A.C.(alternating current) Impedance, were utilized to evaluate the chemical stability of the TaN nanolayer films. The single layer crystalline and amorphous TaN coatings were also investigated for comparison. The amorphous TaN layer exhibited a highest non-negative corrosion potential, Ecorr, around 0.3 V, while the nanolayer coating with amorphous/crystalline stacking possessed a lowest corrosion current, Icorr, of 2.0*10-6 A/cm2. Furthermore, the impedance of the crystalline TaN single nitride coating was enhanced by the heterostructural nanolayer feature.

BP-28 Ab Initio Studies on the Adsoprtion and Adhesive Transfer of Al and Fe to Nitride Coating Materials
Helmut Riedl (Christian Doppler Laboratory for Application Oriented Coating Development at Vienna University of Technology, Austria); Jakub Zálešák (Montanuniversität Leoben, Austria); Matthias Sobiech (Oerlikon Balzers Coating AG, Liechtenstein); Peter Polcik (Plansee Composite Materials GmbH, Germany); David Holec (Montanuniversität Leoben, Austria); Paul Heinz Mayrhofer (Vienna University of Technology, Austria)

Computational studies such as finite element methods (FEM), molecular dynamics or ab initio calculations are integral parts of state of the art materials design. While FEM is commonly used to investigate flow behavior, strain and temperature profiles in various machining processes, this work focuses on utilization of ab initio calculations for an atomistic insight into material transfer phenomena during metal machining.

Material transfer from the workpiece onto the coated tool surface is generally considered as troublesome in machining operations, as the tool and/or work piece surface can severely lack quality over operational time. However, the material adhesion results from a complex interaction of machining conditions, workpiece and coating material. As one crucial parameter we focussed on the tribological contact between nitride coating and work piece material and employed ab initio calculations to estimate the chemical driving force for the formation of transfer material build-up at the coated tool surface.

We thereby investigated the adsorption energies of iron and aluminum with respect to different coating systems (TiN, AlN, TiAlN, TiSiN, CrN, and CrSiN) and were thus able to describe the energetic interplay between workpiece and coating material. The obtained results propose that especially Si containing coatings clearly decrease the adsorption energy for Al, but have less effect on Fe.

The present study introduces a methodology to thoroughly understand tribosystems at the atomic level, which further enables for an efficient coating material screening and selection as an alternative to cost and time consuming experiments.

BP-29 Structure and Elastic Properties of Ternary Metal Nitride Zr1-xTaxN Alloys Thin films: Experimental Study and First-principles Calculations
Philippe Djemia (LSPM-CNRS, Université Paris 13, Sorbonne Paris-Cité, France); QingMiao Hu (Shenyang National Laboratory for Materials Science, China); Mohamed Benhamida, khelil Bouamama (Laboratoire Optoélectronique et Composants, Ferhat Abbas University, Algeria); Laurent Belliard (UPMC, Paris,France); Grégory Abadias (Pprime Institute - UPR CNRS 3346 - Université de Poitiers - ENSMA - France)
We investigated the structure and mechanical properties of ternary alloys thin films Zr1-xTaxN with 0≤ x ≤1 deposited at Ts=300°C by reactive dc magnetron co-sputter deposition from individual Zr and Ta targets in Ar+N2 plasma discharge. The total working pressure was fixed at 0.30 Pa by setting the Ar flow to 16 sccm, while the N2 flow was adjusted to obtain stoichiometric nitride compounds. The structural properties of the ternary Zr1-xTaxN compounds were characterized by X-ray Diffraction and X-ray reflectivity, whereas the picosecond ultrasonic and Brillouin light scattering techniques were employed to measure their acoustic and elastic properties as function of the chemical composition. Density functional theory (DFT) within the generalized gradient approximation with both the virtual crystal approximation and the coherent potential approximation was employed to calculate the electronic structure as well as predict the evolution of the lattice parameter and elastic properties, including single-crystal elastic constants and polycrystalline elastic moduli, of ternary Zr1-xTaxN compounds with cubic rocksalt structure.
BP-31 Electrical and Reliability Characteristics of HfO2 Gate Dielectric Under Oxygen Treatment
Yi-Lung Cheng, Tian-Cih Bo (National Chi-Nan University, Taiwan)
The electrical characteristics and reliability performance of high-k HfO2 dielectric films under various oxygen treatment s are investigated in this study. The films deposited by an atomic layer deposition (ALD) technique using TEMAHf precursor and O3 as the oxidant. For oxygen treatment, thermal or plasma method was performed before and after HfO2 dielectric deposition. The experimental results indicate that irrespective of both oxygen treatment methods, the bulk HfO2 layer remains unchanged, but a thicker interfacial layer was observed for the thermal oxygen treatment. This leads to a better electrical and reliability performance for high-k HfO2 dielectric with thermal oxygen treatment. On the other hand, in case of high-k HfO2 dielectric with plasma oxygen treatment, although improved adhesion ability was observed, a larger stress-induced carrier generation or trapping was detected irrespective of pre- and post-treatments. This results in a degrading reliability performance with a much shorter TDDB lifetime. Therefore, plasma treatment should not use in fabrication of high-k HfO2 gate dielectric.
BP-32 Effect of Ion Irradiation on NI Films Prepared on a Flexible Substrate Material Using Unbalanced Magnetron Sputtering Assisted by Inductively Coupled Plasma
Tatsunori Koda, Hiroshi Toyota (Hiroshima Institute of Technology, Japan)
We fabricated Ni films on a flexible substrate material using unbalanced magnetron sputtering assisted by inductively coupled plasma. A Ni target with a purity of 99.95%, thickness of 5 mm, and diameter of 200 mm was used. Ar gas with a purity of 99.9999% was used as the sputtering gas. The Ar gas pressure was 2.7 × 10−1 Pa. The RF and target DC power were 30 and 700 W. The magnetic flux densities BC on the center axis of the external solenoid were 0, 3, and 5 mT. The substrate DC bias voltages VS were 0, −40, and −80 V. The Ni film was deposited on a polyimide substrate with an area of 15 × 15 mm2 at room temperature. The film thickness was about 750 nm for all samples. To examine the effects of ion irradiation on the fabricated Ni films, we measured the emission spectrum of plasma and substrate current IS by a spectrometer and an ammeter. The properties of the fabricated Ni films were measured by atomic force microscopy (AFM), X-ray diffraction (XRD), and a standard four-point probe method. From the result of emission spectrum, we found that the ArII peak increased with BC and VS. Moreover, IS increased with BC and VS. IS saturated above VS = −40 V for each BC. The value of the saturated IS for BC = 0, 3, and 5 mT was about 52, 180, and 270 mA, respectively. These results suggest that the plasma generated by RF power is expanded toward the substrate surface by BC and that the ions are accelerated toward the substrate by VS. We observed that the value of IS, varied by controlling BC and VS, regulated the extent of ion irradiation. From the result of AFM, we confirmed that the average surface grain size DG increased with BC and VS. For VS = −40 V, DG for BC = 0, 3, and 5 mT was 88.2, 95.4, and 104.4 nm, respectively. We found that DG of the fabricated Ni films increased with IS. From the result of XRD, the (111) and (200) peaks are clearly visible for the fabricated Ni films. The ratio of the integrated intensities I(111)/I(200) increased with VS. Moreover, we confirmed that crystallite size t increased with IS. We found that increase in IS promoted the crystallization of the Ni films. The resistivity ρ of the fabricated Ni films decreased for increasing IS. At BC = 3 mT and VS = −40 V, the measured ρ value of 8.96 × 10−6 ohm*cm was minimum. We determined that the structure of the fabricated Ni films on the flexible substrate material was affected by the values of IS, varied by BC and VS. We conclude that sputtering with ion irradiation is effective for high-quality film formation on flexible substrate material.
BP-33 Effects of Deposition Conditions on ZNO Thin Film Prepared Using RF Magnetron Sputtering
Yousuke Takiguchi, Hiroshi Toyota (Hiroshima Institute of Technology, Japan)
We fabricated ZnO films on a glass substrate by changing target RF power and Ar gas pressure using RF magnetron sputtering. We investigated the effects of deposition conditions on the properties of the fabricated ZnO films from the viewpoint of controlling plasma. A ZnO target with a purity of 99.99%, thickness of 3 mm, and diameter of 101.6 mm was used. Ar gas with a purity of 99.9999% was used as the sputtering gas. As the deposition conditions, we changed target RF power PT and Ar gas pressure PAr in the range of 30-100 W and 0.1-1.1 Pa, respectively. The ZnO film was deposited on an alkali free glass substrate at room temperature. The sputtering time was 10 min constant. To examine the properties of the ZnO films fabricated for each deposition condition, we used atomic force microscopy (AFM), X-ray diffraction (XRD), a standard four-point probe method, and a spectrometer. Moreover, we investigated the effects of controlling plasma by the measurements of emission spectrum using a spectrometer. From the result of the emission spectrum, it was found that the peak intensity of ArⅡ increased with PT and PAr. Increase in the peak intensity of ArⅡ indicates that the number of ions in the vacuum chamber increases. The thickness of the ZnO films T was changed for PT and PAr. T increased with PT, while T decreased for increasing PAr. From this result, for PT, it was found that the deposition rate increased with the number of ions. From the AFM measurements, the average surface grain size DG increased with PT. For PAr = 0.1 Pa, DG for PT = 30, 50, 70, 80, and 100 W was 29.0, 33.8, 48.1, 42.6, and 61.2 nm, respectively. While DG for PAr was about 47.4 nm constant. From these results, it was found that DG of ZnO films was controllable for PT. From the XRD measurements, the (002) and (101) peaks are clearly visible for the fabricated ZnO films. The ratio of the integrated intensities I(002)/I(101) of the ZnO films decreased for increasing PT, while the ratio of I(002)/I(101) increased with PAr. We found that crystal structure of the ZnO films was controllable for PT and PAr. We confirmed that the resistivity ρ of the fabricated ZnO films decreased for increasing PT. In the range of 0.1-0.7 Pa, ρ decreased for increasing PAr, thereafter, ρ drastically increased at PAr = 1.1 Pa. At PT = 70 W and PAr = 0.7 Pa, the measured ρ value of 2.4 × 10-3 ohm*cm was minimum. From the transmittance measurements, we confirmed that the average transmittance was more than 80% in the visible region from 380 to 850 nm for all samples. We found that the controlling plasma by changing PT and PAr affected on the structure of the fabricated ZnO films.
BP-34 Microstructure and Properties of Vanadium Nitride Hard Coating Prepared by Arc Ion Plating
TaeKwang Eom, MooYoung Yoon, ByungHwan Song, CholWeon Yun, SiHoon Song (TaeguTec, Republic of Korea); BongKi Min (Yeungnam University, Republic of Korea)

Recently, high speed dry machining without coolant in the milling application is an important issue in the cutting tool industry to reduce the machining cost and the environmental problems.

One candidate for achieving this goal is deposition of PVD coating layer on the cutting tool which has the rigid low friction property for easy lubrication and high wear resistance in the high speed dry machining conditions.

For that reason, Vanadium Nitride (VN) hard coating has been widely investigated for various cutting tools applications as end mills, drills and various inserts, because of its excellent sliding wear resistance with low friction coefficient (μ=0.4).

Several previous studies have reported that low friction of VN hard coating is come from formation of surface oxide phase, such as V2O5, where the suitable heat and pressure generating conditions are satisfied, and self-lubrication by easy sharing of oxide phase.

In this study, VN films were grown on the commercial cemented tungsten carbide substrate via Arc Ion Plating (AIP) method. And the influence of nitrogen partial pressure and negative substrate bias voltage effects for the microstructure and mechanical properties of VN films were investigated. Additionally, the oxidation behavior of the VN coated layer was also evaluated.

Microstructure, phase and chemical bonding analysis of each coating layer are done by Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS), respectively.

And a ball-on-disc type tribometer was used to identify the fiction characteristics and behaviours of various VN films at the dry sliding condition.

From the research results, VN hard coating in this study can be a potential candidate of the lubricious materials for improving the machining performance at high speed with the dry cutting condition.

BP-35 Selective Textured Deposition of Ti(C,N)
Linus von Fieandt, Mats Boman (Uppsala University, Sweden); Tommy Larsson, Oscar Alm, Jonas Lauridsen (Seco Tools AB, Sweden); Jeanette Persson, Erik Lindahl (Sandvik Coromant R&D Materials and Processes, Sweden)

Multilayer hard coatings are used routinely for metal cutting because they can withstand the extreme conditions that usually prevail. Such coatings need to be hard, have a chemical inertness towards the working piece and they must have an excellent adhesion. In the case of CVD coated cutting tools multilayer coating system is usually used where one or more components is composed of Ti(C,N), often in combinations with Al2O3. It is of importance to understand the nucleation and growth of Ti(C,N) on different substrate surfaces. By increased knowledge and control of nucleation and growth of Ti(C,N), properties such as wear resistance and adhesion can be tailored.

In this work growth of MT-CVD Ti(C,N) on (001) sapphire substrates has been studied by means of X-ray diffraction and electron microscopy. The coatings were extremely fine grained and smooth and were found to have a preferred orientation of (211) despite a large lattice mismatch with the (001) oriented substrate. However, a low intensity peak originating from the (111) plane was observed by XRD suggesting that, at an initial stage, the growth of Ti(C,N) was affected by the substrate. At a later stage, the process switched to growth in the <211> direction.

The reason for this two-step transformation is probably kinetically driven where growth in the <211> direction was favored by a fast growth rate and growth in the <111> direction was favored by an initial matching epitaxy to the sapphire substrate. By changing the process parameters to lower the growth rate, the initial epitaxial growth direction of the T(C,N) could be maintained and coatings having a growth along the <111> direction could be grown.

BP-36 Reduction of Coercivity in Graded X/FePt (X=CoPt, FePd, FePt) Thin Films with Perpendicular Anisotropy
Shih-Hsien Liu (Feng Chia University, Taiwan); Shih-Nan Hsiao (National Synchrotron Radiation Research Center, Taiwan); Shi-Kung Chen (Feng Chia University, Taiwan); Hsin-Yi Lee (National Synchrotron Radiation Research Center, Taiwan)
In recent years, L10-FePt (001)-oriented films have been intensively investigated because of their high magnetocrystalline anisotropy (Ku=7×107 erg/cm3). However, the high anisotropy causes an unfavorable increase in coercivity, which may exceed the writing field of magnetic head. In this paper, we reported that the reduction of coercivity in graded (001) X/FePt films with different top-layers (X=CoPt, FePd and FePt). The 5-nm-thick top-layers were deposited on preheated L10-FePt (001)-oriented films at 500 oC. XRD patterns, exploited by synchrotron radiation, reveal that uniaxial (001) orientation of X/FePt films, due to only appearance of (00l) reflections. Magnetic properties of the films are analyzed using a vibrating sample magnetometer (VSM). Fig. 1 shows the out-of-plane hysteresis loop for the single-layer FePt, and X/FePt films. The coercivity (Hc) of the single-layered FePt film is 10.2 kOe. For FePt/FePt, FePd/FePt and CoPt/FePt films, the Hc are reduced to 2.4, 3.4 and 3.7 kOe, respectively. In term of saturated magnetization (Ms), the Ms of single-layered FePt film is 441 emu/cm3. The Ms are increased when the single-layered FePt films are deposited the top-layers at 500 oC to form graded X/FePt films, which are 606, 650 and 545 emu/cm3 with FePt, FePd and CoPt layer, respectively. In addition, the Ku of X/FePt films are 8×106 erg/cm3 with FePt and FePd layer smaller than that of single-layered FePt films (Ku = 1.2×107 erg/cm3) and CoPt/FePt film (Ku = 1.1×107 erg/cm3). Compared to single-layered FePt films, a significant reduction of maximum Hc ~ 72 %. The Hc is reduced, because the X/FePt films are formed graded structure films. Based on the results of secondary ion mass spectroscopy (SIMS), the formation of graded structure in X/FePt films due to interdiffusion of top-layer and FePt layer was found. Accordingly, the change of magnetic reversal mechanism due to the microstructural evolution results in the reduction of Hc, which will be discussed in the full article.
BP-37 Effect Of The Concentration Of V In Corrosion Resistance Of Vanadium Carbide Coatings Deposited By The Thermoreactive Deposition Diffusion Process (Trd)
Alejandro Orjuela, José Alfonso, Jhon Olaya (Universidad Nacional de Colombia Bogotá, Colombia)

Vanadium carbide coatings onto tool steel AISI H13 and AISI D2 were obtained using thermoreactive deposition/diffusion process (TRD). Four different percentages of ferroalloy were used and Corrosion resistance of vanadium carbide layers was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in a solution with 3.0% of NaCl . The microstructure was characterized by X -ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the coatings thickness increases between 2μm and 10μm with vanadium content. The corrosion resistance increases with increasing the percentage of ferroalloy. Coatings with 20% of ferrovanadium on AISI D2 had the highest corrosion resistance with respect to the layers analyzed. These details are discussed in this research.

BP-40 Production and Characterization of Vanadium Carbide Coatings on Gray Cast Iron by Termorreactive Diffusion / Deposition
ArielAugusto Amaya A., Jhon Olaya, OscarEdwin Piamba Tulcan (Universidad Nacional de Colombia Bogotá, Colombia)

Production research for industrial coatings from thermochemical processes plays an important role in materials science. Thermoreactive Diffusion deposition technique (TRD), points to obtain homogeneous coatings, continuous and resilient simple procedures at cost.

The coating was deposited in gray iron pearlitic matrix with randomly distributed lamellar graphite and 3.5% at total carbon. The process was carried out in a salt bath of molten borax at 940 ° C for 2 to 5 hours. Ferro-Vanadium is used as the carbide-forming element and aluminum as the reducing agent.

The coatings obtained were characterized by scanning electron microscopy (SEM), Auger Electron Spectroscopy (AES), and X-ray diffraction (XRD). SEM showed compact, continuous, homogeneous coatings and smooth interface. From XRD was observed with a composition consisting of VC, with preferential orientation in the (222) and (400). From AES was verified the presence of Vanadium at 471,8 eV and carbon in 266.8 eV. It also determined a significant increase in the Vickers hardness of 510 for a casting to 2506 ± 46 Vickers for Vanadium carbide coating. They found values of surface roughness of 694 microns.Finally it was found that the corrosion resistance and adhesion to the substrate increases, when evaluated by the technique of potenciodimnamic polarization and resistance by the Scratch.

BP-41 Effect of the Concentration Of Nb In Corrosion Resistance Of Niobium Carbide Coatings Deposited by the Thermoreactive Deposition Diffusion Process (TRD)
Alejandro Orjuela, Rosa Rincón (Fundacion Universitaria Los Libertadores, Colombia); Laura Ardila (Universidad Nacional de Colombia Bogotá, Colombia)
Niobium carbide coatings were deposited on low alloy steel AISI 1045, through thermoreactive deposition/diffusion technique (TRD). Corrosion resistance of niobium carbide coatings was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in a solution of NaCl 3.0% varying the percentage of ferroniobium in the TRD process. The microstructure was characterized by X-ray diffraction (XRD) and morphology was characterized by scanning electron microscopy (SEM). Chemical analysis of the layers was obtained by X-ray Photoelectron Spectroscopy (XPS), observing the formation of Nb2O5 layers. The results show that thickness of the carbide coatings not change significantly with increasing ferroalloy. Carbide coatings improved corrosion resistance with respect to the substrates; however, those results were not affected by the percentage of ferroalloy in the salt bath.
BP-42 Characteristic of Multiferroic BiFeO3/LaNiO3 Superlattice Structures Prepared by RF Sputtering
Hsin-Yi Lee (National Synchrotron Radiation Research Center, Taiwan); Yen-Ting Liu (National Chiao Tung University, Taiwan)
Artificial superlattice structures consisting of alternating epitaxial layers of materials with dissimilar physical properties offer exciting new possibilities both in the investigation of fundamental physical phenomena and in the exploitation of novel properties for diverse applications. In this work, symmetric epitaxial superlattice structures of multiferroic BiFeO3 (BFO) and conductive LaNiO3 (LNO) sublayers were grown on a Nb-doped SrTiO3 substrate with rf magnetron sputtering at temperature 660 oC. The superlattices contained 6 – 30 periods of BFO/LNO bilayers with a sublayer thickness in a range 1.7 – 8.5 nm; the total thickness of the films was fixed at ~ 100 nm. We characterized the structure of the interface and the surface morphology of these films by measuring X-ray reflectivity and diffraction. The formation of a superlattice structure was confirmed from the appearance of satellite features on both sides of the main feature in the X-ray diffraction pattern. The periods and thickness of the superlattice confirmed by XRD and XRR are consistent with the results of SIMS. X-ray measurements show that these superlattice films become subject to greater tensile stress along the c-axis and increased compressive stress parallel to the surface plane with decreasing thickness of the sublayer.

The BFO sulayer in the artificial superlattice is under biaxial compressive stress whereas the LNO sublayer is under biaxial tensile stress. The smaller is the thickness of the sublayer, the greater is the crystalline quality and the strain state. The hysteresis loops show a large leakage current at frequencies 0.5 and 1 kHz; the polarization decreases with increasing frequency. An intrinsic remanent polarization of the superlattices was observed at the thickness of a sublayer in the range 1.7 – 8.5 nm at 5 kHz. The rounded shape of the hysteresis loop at frequency ≦ 2 kHz resulted from large dc leakage and extrinsic interface effects.

BP-43 Evaluation of the Erosion-corrosion of Nanocomposite (Fe, 25Cr, 5B, 6Mo, 15W, 3Mg, 4C, 12Ni, 2Si) Deposited on AISI-SAE 4340. Steel through Thermal Spray Arc
Felipe Laverde, José Alfonso, Jhon Olaya (Universidad Nacional de Colombia Bogotá, Colombia)

The thermal spray are a technique of deposit coatings in industrial application for the dimensional recovery surfaces, improve properties corrosives and properties of wear, this technique is easy to apply in different metallic substrates because; the aderencia is done by assembling mechanical by molten particle-propelled by an air stream to speeds of 150 m/s , which is applied after which a pair of wires are melted by an electrical arc. With this technique are deposited coatings from Low Carbon alloys to high engineering alloys as you contain nanocoposites; is important the surface preparation according the NACE 01 for adequate adherence. We studied erosion-corrosion of Nanocomposite coatings (Fe, 25Cr, 5B, 6Mo, 15W, 3Mg, 4C, 12Ni, 2Si) and, stainless steel (Fe, 0.3C, 1Si, 1mn, 13Cr) alloy iron and cobal (Fe, 15CO, 0.8 Mn, 0.2Si), deposited through arc thermal spraying deposited on steel AISI- SAE 4340, each separately and a nanocomposite coating mixing the stainless steel and iron cobalt, respectively. We used the manufacturer's recommended settings in individual coatings and made approximation to the optimal parameters for mixtures, depositing layers of 1mm with a base layer of 95Ni, 5Al. The erosion-corrosion test was conducted in suspension composed of 3.5% NaCl and 10% Si with particle size 50-70 AFS in deionized distilled water and varying the speed and angle of impact at room temperature, we determinated electrochemical parameters from potentiodynamic polarization curves TAFEL in static conditions and under the influence of the jet The mechanism of failure was evaluated through SEM analysis and the surface chemical composition was analyzed by spectroscopy of electrons Auger (SAE).

BP-44 Morphological and Electrochemical Characterization of VXNbYCZ Coatings Produce by Thermo-reactive Diffusion
Sergio Castro Hermosa, José Alfonso, Jhon Olaya (Universidad Nacional de Colombia Bogotá, Colombia)

The transition metal carbides have an unusual combination of physicochemical properties, the among best known are high melting temperatures and hardness, for instance, the vanadium carbide (VC) is a hard transition metal and exhibit some other properties like good corrosion resistance. In the same way, Niobium carbide (NbC) studies have shown that it has a good corrosion resistance at high temperatures. Nevertheless, the studies in production and characterization of ternary carbides of these transition metals (VXNbYCZ) have been very few. Therefore, the aim of this work is to present an experimental study of the structural evolution of VXNbYCZ coatings produced by thermo-reactive diffusion (TRD). The treatments were carried out in a molten mixture constituted of borax, ferro-niobium, ferro-vanadium and aluminum, at 1313 K for 3 hours, using a resistance heating furnace. The crystallographic structure of the coatings was determinated by X-ray diffraction (XRD), the morphology of coatings was observed by cross-sectional optical microscopy and the corrosion resistance was analyzed by potenciodynamic polarization test (Tafel Extrapolation). The XRD analysis shows that the coatings are polycrystalline. The optical microscopy exhibited that the coatings grew in homogeneous form with a regular thickness, and potenciodynamic polarization evidenced that the resistance corrosion enhancement with respect than the bare substrate, because the corrosion current (icorr) is less, and the corrosion potencial (Ecorr) is approximately equal to the reference electrode (SCE).

BP-45 Influence of Magnetron Sputtering Conditions on WTi and Ta Thin Films: Microstructure-stress-electrical Conductivity Relationship
Pierre-Olivier Renault, Eric Le Bourhis, Arnaud Le Priol (University of Poitiers, France); Philippe Muller (Sofradir, France); Hervé Sik (SAGEM Défense Sécurité, France)
This study reports on the influence of sputter-deposition conditions on the structural, electrical properties of two refractory metallic thin films, namely WTi and Ta, and, for two different thicknesses (10 nm and 180 nm for WTi and 20 nm and 100 nm for Ta). WTi (resp. Ta) thin films have been deposited using a planar DC Magnetron sputtering apparatus from WTi alloyed target (70:30 At%) (resp. pure Ta target 4N) in pure Ar working gas. The working pressure ranged from 0.14 to 1.4 Pa, at constant power discharge (150 W for WTi and 300 W for Ta films), without substrate bias and external heating. Both materials if elaborated by PVD techniques, may exhibit two different crystallographic structures: α-phase (b.c.c.) and β-phase (which is cubic A15 for WTi and tetragonal Ab for Ta). The WTi films only show a α-W structure with a strong {110} fiber texture. On the other hand, Ta films require a sublayer of WTi (superior at 4 nm) to show the b.c.c. phase only. For both WTi and Ta thin films, a residual stress transition from tensile-to-compressive stress state has been observed as the working pressure increases. Stress transition is unaffected by thickness reduction for WTi films. On the contrary, residual stress is almost constant with working pressure for Ta ultra-thin films. The measurements have been performed ex situ by using Stoney and X-Ray Diffraction. The stress transition for both materials which have similar atomic mass should happen at roughly the same working pressure. The difference of stress-transition-working-pressure could be attributed to the different power discharge and/or the presence of the WTi sublayer in case of Ta films. Influence of working pressure on electrical properties has been revealed. The evolution of the electrical conductivity is directly correlated to working pressure for both materials as well as to the residual stress state. Thin films microstructure has been highlighted by FIB-TEM observations. WTi and Ta ultra-thin and thin films process-structure-property relations are studied and discussed in relation with the state of the art.
BP-46 Influence of Reducing Agent on Electroless (Ni-P) Coating Process and Optimization of Process Parameters using Taguchi Technique
Rajaraman Muraliraja, Rasu Elansezhian (Pondicherry Engineering College, India)

This paper reports on the improving nickel recovery of electroless Ni-P coating process. At present in electroless nickel coating process the nickel recovery efficiency is only in the order of 25%. Remaining 75% of unrecovered nickel is present in the electrolyte bath as waste. Due to poor nickel recovery from the bath the coating cost of electroless nickel is very high. Hence in spite of having unique advantages of electroless nickel coatings such as improved hardness, wear and corrosion resistance, uniform coating thickness etc., the coating process is not much popular among commercial coating industries. To overcome the above problem an attempt is made in the present study to improve the nickel recovery of electroless coating process. Earlier researchers had tried to recover nickel from the used bath and some of them got success in their attempt by further improving the nickel recovery from 25% - 60%. However no attempts have been made to recover nickel during the coating process. First time in the present study the nickel recovery was improved during the coating process by adding excess amount of reducing agent from 25% to 100% in the bath. In order to find out the influence of reducing agents at different coating intervals, the excess amount of reducing agent was added after 30 minutes, 60 minutes and 90 minutes of start of coating process. Nickel chloride and sodium hypophosphite were used as source of nickel and reducing agent respectively. Coating was carried out on mild steel specimens. Coating was done for two hours and volume of bath was fixed as 200ml. The coating parameter pH was varied at three different ranges as follows: 4-5, 6-7 and 8-9. Anionic surfactant sodium dodecyl sulphate was varied at three different concentrations such as before, at and after critical micelles concentration values and added in the bath. The influence of adding excess amount of reducing agent on nickel recovery efficiency, surface finish, micro hardness, coating thickness, rate of deposition and % of nickel and phosphorous on coated samples were investigated. The result showed that after adding 100% of excess amount of reducing agent at 90 minutes of start of coating the nickel recovery was significantly increased from 25% to 65%. The various coatings parameters used in the electroless bath were optimized using taguchi technique. The complete experimental details, their results and analysis are reported in this paper.

Keywords: electroless plating, nickel recovery efficiency, reducing agent, coating parameters, optimization, surfactant

BP-47 Mechanical and Tribological Properties of Nanocomposite Ti-B-N-Si Films Deposited by High Power Impulse Magnetron Sputtering
Jaeho Jang, Jungsoo Kim, Eunsol An, In-Wook Park, Dae-Geun Nam (Korea Institute of Industrial Technology (KITECH), Busan, South Korea); KwangHo Kim, Ikmin Park (Pusan National University, South Korea)
Multifunctional nanocomposite, based on nanocrystalline and amorphous phases, films attract considerable interest to extend the lifetime of cutting tools, press-forming tools and various other mechanical components. Films for most tribological applications require combinations of properties such as a relatively high hardness, high fracture toughness, wear- and oxidation-resistance, and a low friction coefficient. The present work investigates the co-deposition of Ti-B, Ti-B-N, and Ti-B-N-Si nanocomposite films from a composite target of TiB2 and a pure boron doped Si target using high power impulse magnetron sputtering in Ar/N2 gas mixtures. The mechanical and tribological properties for the films were investigated in various N and Si contents. The microstructures of the synthesized films were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscope (XPS), high-resolution transmission electron microscope (HRTEM), respectively. Nano-indentation was conducted to assess the hardness and Young’s modulus of the films. Nanoindentaion was conducted to assess the hardness and Young’s modulus of the Ti-B, Ti-B-N, and Ti-B-N-Si films. Wear resistance and coefficient of friction of these films were evaluated using a micro-tribometer. This paper will present the effects of Si content on the microstructure, hardness, and tribological properties of a high power impulse magnetron sputtered Ti-B-N-Si films.
BP-48 Structural Investigation of Y- and Hf-Doped TiAlSiCN Coatings
PhilippV. Kiryukhantsev-Korneev, Konstantin Kuptsov, Alexander Sheveyko (National University of Science and Technology "MISIS", Russian Federation); Cristina Rojas, Asuncion Fernandez (Instituto de Ciencia de Materiales de Sevilla, Spain); DmitryV. Shtansky (National University of Science and Technology "MISIS", Russian Federation)

Newly developed TiAlSiCN coatings with specific structure, in which TiAlCN columnar grains 10-30 nm wide are separated by a SiCN amorphous tissue, demonstrate combination of high hardness in a range of 40-50 GPa, elastic recovery >60%, good impact and wear resistance in different environments, corrosion resistance in alkaline solutions, and high thermal stability up to 13000C [1-4]. Even after annealing at 15000C TiAlSiCN exhibits acceptable hardness of 20 GPa, and crystallite size <50 nm. However practical application of TiAlSiCN is still limited by a relatively low oxidation resistance: complete oxidation at temperatures > 10000C [3]. Addition of optimal amount of Y drastically improves the oxidation behavior of the Ti-Al-N-based coatings and promotes grain refinement resulting in lower residual stresses in the coatings. Hf-alloyed TiN and Ti-Al-N coatings show improved oxidation resistance and high-temperature tribological characteristics. The aim of the present work is to study the structure of Y- and Hf-doped Ti-Al-Si-C-N coatings produced by magnetron sputtering and magnetron sputtering combined with metal ion implantation.

The TiAlSiCN composite target for sputtering was produced by self-propagating high-temperature synthesis. High energy bombardment by Hf+ and Yn+ ions was implemented at the initial stage of deposition or assisted during the whole process. Accelerating voltage and current of the MEVVA type ion implanter were kept constant at 30 kV and 10 mA, respectively. Doped coatings were also produced using mosaic cathodes composed of TiAlSiCN and Y or Hf segments. The structure of coatings were studied by means of glow discharge optical emission spectroscopy, X-ray diffraction, X-ray photoelectron, Raman and electron energy loss spectroscopy, high-resolution transmission and scanning electron microscopy. Influence of Y and Hf additives on chemical and phase composition, texture, crystallites geometry, morphology, and topography of TiAlSiCN coatings are discussed. Preliminary results of structural investigation of alloyed coatings after air annealing at T> 10000C are also presented.

[1] F.V. Kiryukhantsev-Korneev et al. Russ. J. Non-Ferr. Met. V. 54, №4 (2013) 330–335.

[2] D.V. Shtansky et al. Surf. Coat. Technol. 206 (2012) 4840–4849

[3] D.V. Shtansky et al. Surf. Coat. Technol. 205 (2011) 4640–4648

[4] K.A. Kuptsov et al. Surf. Coat. Technol. 216 (2013) 273-281
BP-50 Preparation and Characterization of (111)-oriented Ti1-xAlxN Thin Films on Monocrystalline Aluminium Nitride by Reactive Chemical Vapor Deposition
Hiroyuki Shimoda, Frederic Mercier, Sabine Lay, Elisabeth Blanquet (SIMaP CNRS/Grenoble INP/UJF, France)

In this work, we report on the preparation of Ti1-xAlxN thin films by a novel way, namely Reactive Chemical Vapor Deposition (R-CVD). Recently we have grown Ti1-xAlxN films by R-CVD from titanium tetrachloride, hydrogen and c-plane (0001) monocrystalline hexagonal aluminium nitride layers at varied temperature between 800°C and 1200°C. Onemicron-thick monocrystalline AlN layers have been prepared at 1500°C with a gas mixture of NH3 and AlCl3 on c-plane (0001) monocrystalline sapphire substrate1. The Ti1-xAlxN thin films have been analyzed by Field Emission Gun Scanning Electron Microscopy (FEG-SEM), Transmitting Electron Microscope (TEM), and X-ray Diffraction (XRD). Additionally,thermodynamic simulations have been carried out to predict the influence of the major operating parameters.

In this presentation, we focus on the chemical processes between the Ti1-xAlxN solid phase and the chlorine-based gaseous phase. The effect of the process conditions such as temperature, composition of the gas phase, deposition time on the thin films’ properties (composition, thickness) will be discussed regarding both experiments and thermodynamic calculations. As a typical result, 70-nm-thick layer with (111)-oriented cubic Ti1-xAlxN (0.1≤x≤0.45) has been obtained. Work is going on to propose the best conditions for preparing Ti1-xAlxN thin films by reactive CVD.

BP-52 Effect of the Interlayer Thickness on the Adhesion Property of the CrZrN Coatings Deposited on AISI H13 Steel
Kyu-Sung Kim, Hoe-Kun Kim, JungHyun La, Sung-Min Kim, Sang-Yul Lee (Korea Aerospace University, Korea)

Nanocrystalline CrZrN coatings with a Cr interlayer were deposited on AISI H13 steel substrate using unbalanced magnetron sputtering system. Although a metallic interlayer was generally used to improve adhesion property by reducing stress gradient between the coating and the substrate, the effect of the interlayer thickness on the adhesion property of the CrZrN coating has not been studied. In this work, the CrZrN coatings with various Cr interlayer thickness from 0 to 600 nm were deposited and the total thickness of the coating was 3 μm. The hardness, crystalline structure, microstructure, surface roughness, and adhesion property of the CrZrN coatings were evaluated by Fischer scope, X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and scratch tester. The hardness of the CrZrN coatings, ranging from 32-34 GPa, did not show significant dependence on interlayer thickness. The preferred growth orientation of CrZrN coating without interlayer was CrZrN (111). As interlayer thickness increased, the growth orientation changed into CrZrN (220) and at the same time, the rms roughness of CrZrN coating increased from 2 nm with up to 450 nm thick interlayer to 7 nm with 600 nm. The critical load Lc3 showed the maximum value of 32 N at the interlayer thickness of 300 nm. The scratch failure mode changed from the buckling crack and spallation below 450nm to the wedging spallation at 600nm. This result could be attributed to that the shear failures at interlayer became dominant as the thickness of the soft metal interlayer increased.

Acknowledgement

“This research was supported by a grant from the Advanced Technology Center(ATC) Program funded by the Ministry of Trade, Industry& Energy of Korea”

BP-53 Effect of Gas Pressure and Exciting Voltage on the Plasma Stability of a Pulsed-DC Hollow Cathode Discharge
Andreas Benkenstein, Klaus Böbel, Matthias Müller (Robert Bosch GmbH, Germany); Birger Dzur (Ilmenau University of Technology, Germany)

A hollow cathode plasma discharge inside a blind hole has been evaluated concerning its electrical properties and its plasma stability. The governing parameters (i) gas pressure and (ii) exciting voltage were varied and conductivity curves were derived.

The experimental setup was an electrically contacted steel body that was isolated to the ground potential. The working gas Argon was supplied via a ceramic capillary. The dynamic pressure was measured at the end of the blind hole using a MEMS pressure sensor.

First experimental series investigated the relationships between gas flow rate, inner pressure and penetration depth of the capillary. Linear correlations were found (i) between gas flow rate and inner pressure and (ii) between capillary position and inner pressure. Furthermore, the experiments revealed the range of reliable, stable process and measurement conditions that were taken as experimental array for the subsequent investigations.

Oscilloscope measurements revealed the influence of the process input parameters frequency, duty cycle and voltage on the resulting ignition and stability behavior of the plasma. The maximum value of the voltage pulse was found to have the highest influence. This voltage pulse itself can be controlled by the average voltage, the off-time and the frequency.

Based on those results the conductivity curves for different capillary penetration depths, gas flows and voltages were established. The conductivity curves clearly revealed the range of the plasma stability: The lower limit is the transition to the normal glow discharge while the upper limit is the transition to the arc discharge that is detected by the power supply as a voltage drop. Additionally a strong influence of the capillary position not only on the pressure but also on the electrode surface area and hence on the resulting current was found.

BP-55 Structure and Mechanical Properties of Ta Alloyed Cr-Al-N Coatings
Robert Hollerweger, Liangcai Zhou (Vienna University of Technology, Austria); David Holec (Montanuniversität Leoben, Austria); Richard Rachbauer (Oerlikon Balzers Coating AG, Liechtenstein); Peter Polcik (Plansee Composite Materials GmbH, Germany); Paul Heinz Mayrhofer (Vienna University of Technology, Austria)

Transition metal alloying of Cr1-xAlxN based coatings is commonly used to improve their mechanical properties and thermal stability. Recent reports show that Tantalum additions to Ti1-xAlxN type coatings positively influence their properties, but only little information is available on the effect of Ta on Cr1-xAlxN based coatings. Consequently, we have performed a combined experimental and ab initio based study on the influence of Ta additions (0, 2, 6, 12, and 26 at% on the metal sublattice) on structure and mechanical properties of arc evaporated Cr1-x-yAlxTayN coatings with Al/(Cr+Al) ratios > 0.61. With increasing Ta-content the droplet number density decreases and coating surface smoothens, which is much more pronounced as with increasing the bias voltage from ­­–40 to –120 V. Simultaneously, the columnar structure observed for Ta-free Cr0.37Al0.63N significantly changes into a fine grained structure (crystallite size ~5 nm) with clearly reduced columnar character. Additionally, increasing the Ta content favors the formation of a preferred 200 growth orientation resulting in a reduction of the indentation moduli from ~500 to ~375 GPa, which is in agreement with ab initio calculations. As the hardness of our coatings remains at ~35 GPa with increasing Ta content, this indicates an increase in fracture toughness at still high resistance against plastic deformation.

BP-58 Tribocorrosion Properties of Duplex MAO/DLC Coatings on Ti6Al4V Alloys
EbruEmine Sukuroglu, Yasar Totik, Ersin Arslan, Ihsan Efeoglu (Atatürk University, Turkey)
In the recent years, various technologies are being increasingly investigated for the surface modification of Ti and Ti alloys. Micro arc oxidation (MAO) is the one of the effective technique to improve the surface properties. However, it has some disadvantages for sliding wear applications and/or aggressive environments. In this study, the combined MAO and closed field unbalanced magnetron sputtering process was used to deposit duplex MAO/DLC coatings on Ti6Al4V alloy. The microstructures, morphology and crystallographic structure were analyzed by SEM, RAMAN and XRD. The wear, corrosion and tribocorrosion properties of the coatings were investigated by pin-on-disc wear test, potentiodynamic polarization test and combining tribocorrosion test unit, respectively. The results were show that duplex MAO /DLC coating exhibits a better wear, corrosion and tribocorrosion properties than the DLC or MAO monolayer on Ti6Al4V alloy substrate. MAO /DLC coatings exhibited dense structure, lower coefficient of friction and corrosion current density and the higher tribocorrosion resistance. The results were also showed that MAO /DLC duplex coatings on Ti6Al4V substrates increased the tribocorrosion resistance by acting as a barrier layer.
BP-59 Effect of Coating Thickness on the Silt Erosion Properties of Ternary Metal Nitride Thin Films prepared by Magnetron Sputtering
Vivek Arya (BHEL R&D, India); Paritosh Dubey, Ramesh Chandra (Indian Institute of Technology Roorkee, India)
Silt erosion is a predominant phenomenon due to excessive silt present in water passing through under-water hydro turbine components affecting their life and efficiency. In recent years, binary and ternary transition metal nitride materials have played a crucial role in various engineering applications due to their remarkable physical and mechanical properties including high hardness, high melting point, chemical inertness and good thermodynamic stability. The role of nano composite thin films deposited by PVD techniques such as DC/RF magnetron sputtering is increasing prominently for combating silt and cavitation erosion. In the present study, ternary systems such as Titanium Silicon Nitride (Ti-Si-N) and ‘Tungsten Zirconium Nitride (Zr-W-N) has been deposited on 13Cr-4Ni stainless steel substrate by DC/RF reactive magnetron sputtering. These thin films have been deposited with varied thickness in the range of 1-2 μm, 5-7 μm and 10-15 μm by varying coating parameters. The effect of coating thickness on silt erosion of these films, their damage mechanism and its correlation with mechanical properties are discussed in detail. The silt erosion resistance of these coatings has been compared with base material. It is observed that the silt erosion resistance of nano composite thin films has been improved significantly with increase in coating thickness.
BP-60 Fabrication and Characterization of Tungsten-Yttrium Coatings for Nuclear Reactor Applications
Gustavo Martinez (University of Texas at El Paso, US); Chintalapalle Ramana (University of Texas at El Paso)

The challenging problem currently facing the scientific community in this 21st century is design, fabrication and engineering of novel structural materials, which will have a technological impact on the development of next-generation nuclear reactors to secure current, emerging and future energy needs of the society. Specifically, the choice of structural materials and options for nuclear reactors is very challenging for the reason that these materials experience: (a) extreme conditions of temperature and pressure, (b) high levels of nuclear irradiation, and (c) high mechanical and thermo-mechanical stresses. Tungsten-based materials have been considered for nuclear reactor applications for many years. While pure W exhibits compatible properties, it has low fracture toughness at all temperatures [#] . In addition, it exhibits a high ductile to brittle transition, which depends on the chemical and microstructure. Therefore, alloying W with other metals has been considered to further improving the physical properties and mechanical properties. In this work, alloying W with yttium (Y) has been considered to develop the structural materials for nuclear applications. W-Y (Y<10 wt.%) coatings were deposited by RF sputtering. Characterization of these coatings is performed to derive an understanding of the micro-structure, thickness evolution, specific phase formation and/or transformation, and texturing with respect to deposition conditions. Coatings deposited at 3.4x10-2 mbar exhibit better structural order with a completely dominant β-phase when compared to the samples deposited at sputtering pressure of 1.4x10-2 mbar. The deposition rate (Γ) also decreases from 21 to 10 nm with increasing argon pressure from PAr=1.9E-2 mbar to 3.4E-2 mbar. Rutherford backscattering (RBS) spectroscopy of W-Y films demonstrated Y inclusion in the lattice [#] in the range of 1-5 wt%. The average grain size decreases with increasing pressure. Calculations were made using the Stopping and Range of ions in Matter (SRIM 2013) simulation package to understand the ion-irradiation damage as a function of time. The results will be presented and discussed.