ICMCTF2012 Session BP: Symposium B Poster Session

Thursday, April 26, 2012 5:00 PM in Golden Ballroom

Thursday Afternoon

Time Period ThP Sessions | Topic B Sessions | Time Periods | Topics | ICMCTF2012 Schedule

BP-1 Trends in elasticity of binary and ternary transition metal aluminium nitrides
Peter Wagner (Montanuniversität Leoben, Austria); Martin Friák (Max-Planck-Institut for Iron Research, Germany); Paul Mayrhofer, David Holec (Montanuniversität Leoben, Austria)

Protective hard coatings make use of the outstanding mechanical and thermal stability of early transition metal nitrides (TMN) and their alloys with Al. Modern applications require sophisticated designs of the protective thin films in which a multiscale modelling plays an important role. For example, stress management of the thin film is a crucial factor affecting its high temperature stability. This is an ideal task for the finite elements method where elastic properties of the studied materials are the necessary input.

The scatter of published elastic constants for the systems of interest is enormous. For example, for TaN one can find the value of C11 ranging from 680 GPa to 880 GPa. This of course raises questions about reliability not only of the first principle calculations but also the subsequent larger-scale modelling using these values as inputs as well as how compatible are the values published in various papers.

In this paper we critically revise the computational methodology of second and third order elastic constants calculations focusing on a large family of binary TMN (TM=Sc, Ti, V, Y, Zr, Nb, La, Hf, Ta) and AlN in their cubic (B1, NaCl prototype) modification. Apart from the single crystal properties, also estimates for polycrystalline samples will be discussed which are more appropriate for modelling of the thin films. In addition, we will present description of the single crystal and polycrystalline elastic behaviour of the ternary Zr1–xAlxN system.

BP-2 Investigation of the mechanical properties of ternary metal nitrides TMxMo1-xN and TMxW1-xN with TM=Ti, Zr, V, Nb, Ta and Cr
Khelil Bouamama (Ferhat Abbas University, Algeria); Philippe Djemia, Damien Faurie (University Paris 13, France); Gregory Abadias (Institut P' - Universite de Poitiers, France)
First-principles pseudopotential calculations of the lattice constants and of the single-crystal elastic constants for ternary metal nitrides TMxMo1-xN and TMxW1-xN with TM=Ti, Zr, V, Nb, Ta and Cr (0 ≤ x ≤ 1) alloys considering the cubic B1-rocksalt structure were carried out. These calculations were performed using density functional perturbation theory (DFPT) within the virtual crystal approximation (VCA) for the disordered alloys and the supercell method (SC) for the ordered alloys. For the exchange-correlation potential, we used the generalized gradient methods (GGA). The calculated equilibrium lattice parameters exhibit a deviation from Vegard’s rule with a bowing parameter that depends on the transition metal. The calculated single-crystal stiffness, namely C44 and C12, gradually increases or decreases, respectively from TMN to (Mo,W)N. In case of Ti and Zr metals, we observe three regions: unstable, ductile and brittle whereas for the other alloys, only the unstable and the ductile behaviours are found. The transition metal concentration x for which occurs the transition from unstable to stable mechanical state depends on the element TM. In a second stage, in the frame of anisotropic elasticity, we have estimated by homogenization methods the averaged stiffnesses <Cij>, direction dependent Young's moduli and Poisson's ratios of some polycrystalline T Mx(Mo,W)1-xN alloys considering a crystallographic fiber texture for comparisons with experimental results available in literature.
BP-3 Structural and elastic properties of ternary metal nitrides TixTa1-xN alloys: first-principles calculations versus experiments
Mohamed Benhamida (Laboratoire Optoélectronique et Composants, Ferhat Abbas University, Algeria); Khelil Bouamama (Ferhat Abbas University, Algeria); Philippe Djemia (University Paris 13, France); Laurent Belliard (UPMC, France); Damien Faurie (University Paris 13, France); Gregory Abadias (Institut P' - Universite de Poitiers, France)
First-principles pseudopotential calculations of the lattice constants and of the single-crystal elastic constants for TixTa1-xN (0 ≤ x ≤ 1) alloys with B1-rocksalt structure were first carried out. These calculations were performed using density functional perturbation theory (DFPT) within the virtual crystal approximation (VCA) for the disordered alloys and the supercell method (SC) for the ordered alloys. For the exchange-correlation potential we used the generalized gradient methods (GGA). The calculated equilibrium lattice parameters exhibit a positive deviation from Vegard’s rule corresponding to a positive bowing parameter while the calculated single-crystal stiffness C12 and C44, gradually increase when C11 decreases from TaN to TiN. In a second stage, we have estimated by homogenization methods in the frame of anisotropic elasticity the averaged stiffnesses <Cij>, direction dependent Young's moduli and Poisson's ratios of polycrystalline TixTa1-xN (0 ≤ x ≤ 1) alloys considering different fiber texture. Finally, comparisons are made with the shear elastic modulus Gyz=Gxz and the out-of-plane longitudinal elastic constant C33 measured by Brillouin light scattering and picosecond ultrasonics on thin films elaborated by magnetron sputtering, respectively.
BP-4 Growth of Zirconium Oxide by Heat Treatment of Zirconium Nitride Film under Controlled Atmosphere and Vacuum
Jhih-Wei Shine, Ge-Ping Yu, Jia-Hong Huang (National Tsing Hua University, Taiwan)
Previous study (1) indicated poor wettability of ZrO2 on stainless steel. The purpose of this study was in an attempt to solve this wettability issue by growing ZrO2 from heat treatment of ZrN thin films on stainless steel substrate. Thin film specimens of ZrN were annealing at temperatures ranging from 700 °C to 900 °C and over durations ranging from 0 to 4 hours. To prevent severe oxidation, two environments including vacuum (5x10-6 Torr) and forming gas (N2/H2=9) were selected. The behavior of growing zirconium oxide was investigated by analyzing the oxygen penetration depth, phase distribution, microstructure change, and corrosion resistance of the specimens. X-ray diffraction showed that ZrO2 phase appeared when the specimen was heat treated at 900 °C for 1 hour in vacuum, while ZrO2 appeared at 700 °C for 1 hour in the forming gas. Furthermore, the morphology of ZrN specimens annealed in vacuum was different from that in the forming gas under the same condition. Since the oxygen content in the forming gas was much lower than that in vacuum, the surface conditions of ZrN thin films may be different in vacuum and the forming gas. During oxidation, cracks and blisters may form on the specimen surface due to large difference in molar volume (about 50%) between ZrO2 and ZrN. SEM observation revealed that cracks and blisters in ZrO2 layer on the ZrN specimen appeared in the forming gas environment at temperature 700 °C and above while no blister in ZrO2 layer was observed in the vacuum environment. The results of residual stress measurement indicated that for the ZrN specimens heat treated in vacuum, the stress induced by volume expansion due to phase transition from ZrN to ZrO2 was released significantly as ZrO2 phase showed up. Thus, by selecting a proper environment, a thin layer of ZrO2 could be grown from ZrN without crack or blister formation, which may provide good corrosion protection.

1. Jia-Hong Huang, Tzu-Chun Lin, Ge-Ping Yu, Surf. Coat. Technol., 206(2011)107.

BP-5 Microstructure and Characterization of Sputtered Ni-based Films Codeposited with Ru and P
Kun-Yuan Liu, Yu-Cheng Hsiao, ChihKun Chang, Fan-Bean Wu (National United University, Taiwan)
The Ni-Ru, Ni-P, and Ni-Ru-P alloy films are manufactured by d.c. sputtering technique. The Ni-Ru films show a granular structure as the Ni-P and Ni-Ru-P coatings exhibit an amorphous feature in the as-deposited state. However, when the Ru content is raised to 52.7 at.%, the Ni-Ru-P transforms to a Ni + Ru + Ru2P multiphase crystallized microstructure. The granular Ni-Ru coatings posses relatively low corrosion resistivity, while a superior chemical stability is deduced for the P incorporated Ni-based alloy films. The lower corrosion characteristic for the Ni-Ru is attributed to the Ni-based granular structure providing corrosion paths at grain boundaries. The P containing Ni-P and Ni-Ru-P sputtered films show an amorphous phase, in which the fast corrosive paths are eliminated, and thus enhance the corrosion resistance. On the other hand, the chemically stable Ru and Ru2P phases are beneficial to the superior corrosion resistivity for the multiphase Ni-Ru-P coating with high Ru content.
BP-7 Optimizing the PVD TiN thin film coating's parameters on AL 7075-T6 alloy for higher coating adhesion and better surface quality
Erfan Zalnezhad (University of Malaya, Malaysia)

Abstract

An optimization study on the parameters of Titanium Nitride thin film coating on Al7075-T6 alloy, using magnetron sputtering technique is presented. The effects of the film thickness, temperature, DC bias voltage, rate of nitrogen and DC power on the adhesion and microstructure of the coated samples are investigated. Each sample is coated at two steps. Firstly samples are coated with pure Titanium and secondly they are coated with titanium nitride which this effort is increased the adhesion of TiN to surface profoundly. The coating properties probed in this work included the surface thickness, morphology of deposited coating, adhesion between the coating and substrate, and surface characterization using a field emission scanning electron microscope (FESEM) with energy dispersive X- ray (EDX), X-ray diffraction (XRD). SEM analyses showed that all the films had columnar and dense structure with clearly defined substrate-film interfacial layers. Scratch result showed, the adhesion between substrate and thin film was increased with increasing the DC power from 300W to 500W. The result also showed an increase; in dc bias voltage, the adhesion was increased from 25V to 75V, but with more increasing (100V) the adhesion was decreased.

BP-8 Analysis of damaging phenomena of coated cutting tools using hardened die steels
Kana Morishita (Hitachi Tool Engineering, Ltd., Japan)
Machining of hardened die and mold steels has been increasing due to requirements of manufacturing at short delivery time and reducing manufacturing cost. However, machining of hardened die steels is technically difficult and cause early damage of cuttings tools. It is commonly known that wear of cutting tools can be reduced by formation of a oxide layer “Belag” on cutting edge. In this research, we investigated damage modes of TiN and TiAlN coated cutting tools and their mechanisms aiming to improve machinability of high-hardness die and mold steels. For this purpose, the wear surface and closs-section after cutting was investigated using FE-EPMA, TEM, and STEM. Particularly, the adhesive materials formed on the cutting edges were analyzed and tools damage was studies.

EPMA analysis of tool-work interface showed that the belag was formed on the coating surface during cutting, which was Mn-Si-O or Al-O. Formation of the Mn-Si-O based belag could help increasing the cutting speed compared to formation of an Al-O based belag, while Al-O based belage was performed as protective layer against wear resistance. The belag formation was related to the chemical composition of work materials, chemical composition of the coatings and cutting temperature.

BP-9 Annealing effects on nanostructure and mechanical properties of laminated Ta–Zr coatings
Yung-I Chen, Sin-Min Chen (National Taiwan Ocean University, Taiwan)

The as-deposited laminated Ta–Zr coatings exhibited nanocrystalline or amorphous states, depending on the chemical compositions. As annealed in oxygen containing atmospheres, Zr oxidized preferentially. The hardness increased as the oxygen content in the coating increased, due to the formation of ZrO2. To behave as a protective coating applied in high temperature with an appropriate hardness, such as coatings on glass molding dies, the coating need to endure annealing treatment in an oxygen containing atmosphere at 600 oC. In this study, the periods of laminated coatings were controlled by rotating speeds of the substrate holder. T he annealing treatments were conducted at 600 oC under atmospheres of 20 and 50 ppm O2-N2, respectively. The variations in crystalline structure, hardness, surface roughness and chemical composition profiles in depth after various annealing times were investigated. The lifetime of a protective Ta–Zr coating was justified by exposed the coating in a 50 ppm O2-N2 environment to achieved a high hardness of 10 GPa and then annealed in a 20 ppm O2-N2 atmosphere for long times.

BP-10 Influence of thickness on mechanical and corrosion properties of Ti-Si-N coatings on D2 steel by unbalanced magnetron sputtering.
Yun-Kai Cheng, Ge-Ping Yu, Jia-Hong Huang (National Tsing Hua University, Taiwan)

In order to fulfill the requirements in industrial applications, hard coatings possessing both high hardness and good corrosion resistance are demanded. Ti-Si-N is one of the coatings that have been extensively studied in recent years. Most studies on Ti-Si-N coatings were focused on the hardening mechanisms due to structure evolution, composition variation, or impurity effect; however, few studies have been performed on the relation between residual stress and thickness variation. In this study, a series of Ti-Si-N coatings were deposited on AISI D2 tool steel without interlayer using unbalanced magnetron sputtering at different deposition durations. The coating thickness of all specimens was larger than 1μm. The purpose of this study was to investigate the mechanical properties and corrosion resistance of the Ti-Si-N coatings. X-ray diffraction results showed that the thick Ti-Si-N coatings were composed of nanocrystalline TiN and amorphous Si3N4. Coating thickness was obtained from focused ion beam (FIB) measurement. X-ray photoelectron spectroscopy (XPS) was used to characterize the bonding state and compositions of the coatings. The hardness of the coatings was measured by nanoindentation. The residual stress was determined by modified sin2ψ x-ray diffraction and laser curvature methods to explore the residual stress state and stress distribution in the coatings. The adhesion of Ti-Si-N coatings was evaluated by scratch test. The influence of the coating thickness on corrosion resistance was evaluated by potentiodynamic scan and salt spray test. From the corrosion results, the thick Ti-Si-N coatings could effectively prevent the D2 steel from corrosion. The hardness of the coatings was related to the compositions and texture. The coating thickness was correlated to the residual stress, where a critical stress was found for the spallation of the coatings.

BP-11 Effect of Nitrogen Flow Rate on The Structure And Mechanical Properties of TiZrN Thin Films by Unbalanced Magnetron Sputtering
Chia-Wei Lu, Jia-Hong Huang, Ge-Ping Yu (National Tsing Hua University, Taiwan)

Nanocrystalline TiZrN films were produced using unbalanced magnetron sputtering. The aim of this study was to investigate the effect of nitrogen flow rate on the microstructure and properties of the TiZrN films with nitrogen flow controlled form 1.3 to 2.5 sccm. Thin films of TiZrN were deposited by magnetron unbalanced sputtering on our previous optimum coating conditions for TiZrN. The results of the variation of nitrogen flow rate did not significantly affect the film thickness. The major effects of the nitrogen flow rate were on the texture coefficient, N/(Ti, Zr) ratio, hardness, and resistivity of the TiZrN films. The texture coefficients could be calculated from the integrated intensity of the corresponding XRD peaks. The results indicated that (111) plane was the dominant preferred orientation for all TiZrN specimens. Two other peaks (200) and (220) of TiZrN films could be observed for the specimen at higher nitrogen flow rate. The N/(Ti, Zr) ratio of the TiZrN films increased with respect to the nitrogen flow rate, but increased slowly as nitrogen flow rate further increased. Hardness of TiZrN films first increased to its maximum of 33.1GPa and then decreased as nitrogen flow rate further increased. The result showed that film hardness was not directly dependent on the (111) preferred orientation. The hardness of TiZrN thin films was due to solid solution strengthening and nanograin boundary sliding mechanism. The electrical resistivity and packing density of thin film related to the lattice defects. Similar to hardness, packing density also increased to a maximum at a critical nitrogen flow rate and the lowest resistivity corresponded to the highest packing density.

BP-12 Ternary d-TixTa1-xN: An addition to superhard materials?
Loukas Koutsokeras (University of Ioannina, Greece); Amalia Skarmoutsou (National Technical University of Athens, Greece); Gregory Abadias (University of Poitiers, France); Pandora Psyllaki (Technological Education Institute of Piraeus, Greece); Constantinos Charitidis (National Technical University of Athens, Greece); Christina Lekka, Panos Patsalas (University of Ioannina, Greece)

The quest of ultraperformant, hard protective coatings [1] is of major technological importance due to their applications in cutting tools, automotive and space industry, among others. Within this framework materials that exhibit hardness above 40 GPa are considered as superhard. Supehard materials are usually nanostructured, like the well known nc-TiN/a-Si3N4 [1]. Recently it was possible to grow the ternary compound d-TixTa1-xN [2] and its hardness has been measured to be as high as 42 GPa [3]; the later makes it a strong candidate for being a member of the group of superhard materials.

In this work, we investigate the effects of composition and microstructure of d-TixTa1-xN coatings on their mechanical performance. The d-TixTa1-xN coatings have been grown by dual-cathode magnetron sputtering (DCMS) and dual ion beam sputtering (DIBS). The DIBS-grown samples exhibit globular grain morphology and similar grain sizes for all values of x. On the contrary, the DCMS-grown samples exhibit strong variations of their microstructure, from globular to strongly columnar, with varying x, as identified by X-ray Diffraction and Electron Microscopy analyses. Therefore, by comparing their mechanical performance we can discriminate the effects of composition and microstructure. The mechanical testing has been performed in terms of hardness measurements by nanoindentation, tribological testing by lateral force measurements and wear testing by ball on disk measurements. According to ab-initio calculations of the elastic moduli, the pure d-TaN was expected to be the hardest member of the d-TixTa1-xN family. However, the experimentally produced d-TaN coatings are defective and underdense [4,5]. Here we prove that alloying TiN with TaN improves the mechanical performance by stabilizing the rocksalt structure for Ta-rich ternary d-TixTa1-xN coatings, which are harder than their constituents (TiN, TaN). Indeed, the Ta-rich d-TixTa1-xN coatings were superior in most aspects of mechanical testing.

[1] S. Veprek, J. Vac. Sci. Technol. A17, 2401 (1999).

[2] L.E. Koutsokeras, G. Abadias, Ch.E. Lekka, G.M. Matenoglou, D.F. Anagnostopoulos, G.A. Evangelakis, P. Patsalas, Appl. Phys. Lett. 93, 011904 (2008).

[3] G. Abadias, L.E. Koutsokeras, S.N. Dub, G.N. Tolmachova, A. Debelle, T. Sauvage, and P. Villechaise

J. Vac. Sci. Technol. A 28, 541 (2010).

[4] C.-S. Shin, D. Gall, P. Desjardins, A. Vailionis, H. Kim, I. Petrov, J.E. Greene, M. Odén, Appl. Phys. Lett. 75, 3808 (1999).

[5] G.M. Matenoglou, L.E. Koutsokeras, Ch.E. Lekka, G. Abadias, S. Camelio, G.A. Evangelakis, C. Kosmidis, and P. Patsalas, J. Appl. Phys. 104, 124907 (2008).
BP-13 Paramagnetic centers in hard graphite-like amorphous carbon
Gustavo Viana, Francisco Marques (Universidade Estadual de Campinas, Brazil)

In this work we investigate the origin of paramagnetic centers in hard graphite-like amorphous carbon. The films were deposited by 1) plasma enhanced chemical vapor deposition (PECVD) using the decomposition of methane (CH4) and 2) sputtering, using an argon ion gun to sputter a pure graphite target. High concentration of sp2 films was obtained adopting high bias in the PECVD technique. These films have small band gap (0.5-1.0eV) and hardness of approximately 15 GPa. The films prepared by the sputtering technique have sp2 concentration of approximately 90 %, zero energy band gap and hardness of 20-30 GPa. Electron spin resonance (ESR) was performed at the X-band (9.4 GHz) microwave frequency using 100 kHz field modulation. A non-saturating power of 5 mW was adopted. The ESR measurements revealed an unexpected low density of paramagnetic centers, ascribed to conduction electrons with a g-value of about 2.003. These results are compared with data reported for amorphous carbon films deposited by different techniques and with different sp2 concentrations.

BP-14 Effects of sputtering gases on the preparation of boron nitride films using RF sputtering
Mai Imamiya (Graduate School, Chiba Institute of Technology, Japan); Yukihiro Sakamoto (Chiba Institute of Technology, Japan)

Many researches of thin film preparation and application for nitride films were reported. Nitride films have fascinate properties such as high hardness, wear proof, electrical properties and so on. On the other hand, boron nitride is one of the artificial material which doesn’t exist naturally. Cubic boron nitride has high hardness and thermal conductivity next to diamond. Investigation was carried out on the effects of sputtering gases on the preparation of BN films using RF sputtering and preparation of BN films on the CVD diamond substrates.

Boron nitride was prepared using RF reactive sputtering. Si and CVD diamond were used as the substrates. Mixture of Ar-N2 and Ar-NH3 were used as reactive sputtering gases. The ratio of Ar:N2 and Ar:NH3 were 1:1, 1:3 and 1:5. Sputtering time was fixed to 1 h. CVD diamond substrates were synthesized using microwave plasma CVD. To obtain CVD diamond substrates, CH4-H2 was used as a reaction gases for diamond synthesis. CH4 flow rate was 1 SCCM, H2 flow rate was 100 SCCM and pressure was 5.3 kPa, microwave power was 400 W, respectively. Reaction time was fixed to 5 h. Surface of deposits was observed using SEM. Deposits were e stimated by XPS and Raman spectroscopy.

As a result of SEM observation of the film on the Si substrates, surface morphologies of sputtered films were smooth. From XPS measurement, the B-N bond was observed in XPS spectra of each samples. Hardness of the film was increased and friction coefficient was decreased with increasing of N2 ratio in Ar-N2 sputtering gas for the Si substrate. As a result of SEM observation of the film on the CVD diamond substrates, BN film on CVD diamond crystals was recognized in each condition. In addition, diamond peak at 1333cm-1 and the amorphous boron nitride peak at 1550 cm-1 were observed in Raman spectra for Ar-N2 sputtering gas. From XPS measurement, B-N bond was obtained in XPS spectra of each samples.

As a conclusion, high hardness BN films could be obtained in not so slow deposition rate using Ar-NH3 sputtering gas. Moreover preparation of the BN film on the CVD diamond substrates could be performed.

BP-15 Influence of Silicon-doping on MSIP Al2O3 coatings
Kirsten Bobzin (Surface Engineering Institute - RWTH Aachen University, Germany); Nazlim Bagcivan (RWTH Aachen University, Germany); Mara Ewering (Surface Engineering Institute - RWTH Aachen University, Germany)

Crystalline alumina PVD-coatings offer high potential for different applications in which high chemical inertness, high hot hardness and high oxidation resistance is important. Especially the metastable γ-phase is topic of many researches because, in comparison to the stable a-phase, it can be deposited by means of MSIP (Magnetron Sputter Ion Plating) at relatively low process temperatures below 650 °C and it is more fine-grained than α-Al2O3. At high temperatures γ-Al2O3 transforms into α-Al2O3, which limits the application temperature. But until now it is not clearly investigated, up to which temperatures γ‑Al2O3 thin films are stable and which mechanisms influence the stability. In the following paper the influence of doping with Silicon is investigated. DSC (differential scanning calorimetry) as well as XRD (X-Ray diffractometry) measurements show that adding 4 at-% Silicon leads to a high amount of amorphous phase in the as deposited coating and a decreasing in hardness from 18 to 10 GPa. Nevertheless formation of the a-phase is retarded to temperatures above 1200 °C while for the undoped coating the α-phase is formed at temperatures of 1100 °C. For the Si-doped coating a transformation via the θ-phase was detected which is not seen for the undoped coating. In combination with a (Ti,Al)N-interlayer, which is necessary to provide a sufficient adhesion, Silicon improves compound properties after thermal exposure. This was proven by scratchtests and impact testing before and after annealing the samples at 900 °C.

BP-16 3-dimensional DLC coating on microgear by bipolar PBII &D and plasma analysis
Wonsoon Park, Junho Choi, Takahisa Kato (The University of Tokyo, Japan); Wonsik Lee (Korea Institute of Industrial Technology, Republic of Korea)
Diamond-like carbon coatings were deposited on microgears by using a bipolar-type plasma based ion implantation and deposition technique (bipolar PBII&D) and the plasma behavior was analyzed by particle-in-cell Monte Carlo simulation. The gas pressure was 0.4 Pa and negative and positive pulse voltages of -2.0 kV and +1.5 kV, respectively were applied to the target. The particle-in-cell method was used for the analysis of electromagnetic fields and the motion of charged particles and Monte Carlo collision method was used for the analysis of collisions of ions, electrons and neutrals in the plasma. In this study, we investigated the distributions of potential, electron and ion densities, and ion flux around the microgear immersed in Methane plasma.
BP-17 Mechanical properties and oxidation resistance of TiSiN/CrAlN films synthesized by a cathodic arc deposition process
Yin-Yu Chang (National Formosa University, Taiwan); Yau-Yi Liou (MingDao University, Taiwan)
Transition metal nitrides, such as TiSiN and CrAlN, have been used recently as protective hard coatings due to their excellent tribological properties. In this study, TiSiN, CrAlN and multilayered TiSiN/CrAlN coatings were synthesized by cathodic-arc evaporation with plasma enhanced duct equipment. The deposition of CrN under the TiSiN/CrAlN was used as an interlayer to enhance better adhesion. With different cathode current ratios (I[TiSi] /I[CrAl]), the deposited TiSiN/CrAlN coatings possessed different chemical contents and periodic thicknesses. For the high temperature oxidation experiment, the deposited TiSiN, CrAlN and multilayered TiSiN/CrAlN samples were annealed at 800oC in air for 2 hours. The microstructure of the deposited coatings was investigated by a field emission gun high resolution transmission electron microscope (FEG-HRTEM, FEI Tecnai G2 20 S-Twin), equipped with an energy-dispersive x-ray analysis spectrometer (EDS), operated at 200 keV for high-resolution imaging. Glancing angle X-ray diffraction was used to characterize the microstructure and phase identification of the as-deposited and annealed films. The composition, chemical bonding and depth profile were evaluated by X-ray photoelectron spectroscopy. Mechanical properties, such as the hardness and elastic modulus, were measured by means of nanoindention. To evaluate the impact resistance of the deposited coatings, an impact test was performed using a cyclic loading device. The design of multilayered TiSiN/CrAlN thin films is anticipated to inhibit the grain growth, and leads to grain refinement effect, which expected to increase the hardness and impact resistance of multilayer films. Meanwhile, the multilayered TiSiN/CrAlN, which forms stable and dense diffusion barriers at high temperature, is expected to possess good resistance to high temperature oxidation.
BP-18 Structural, Mechanical and Tribological Properties of TiTaBN CompositeGraded Coatings Deposited by CFUBMS Technique
Özlem Baran (Erzincan University, Turkey); İhsan Efeoglu (Ataturk University, Turkey); Braham Prakash (Lulea Technical University, Sweden)

Hard coatings based on transition metal nitrides, carbides or borides gained increasing importance. The properties of these hard coatings have been enhanced by adding with other elements such as Al, Si, Cr, V, Mo, etc. In this study, structural, mechanical and tribological properties of TiTaBN coatings obtained with Ta incorporation into TiBN were investigated. TiTaBN films were deposited on D2 steel and glass substrates using pulsed-dc closed field unbalanced magnetron sputtering (CFUBMS) with Taguchi L9 (34) experimental method. Morphology and structure of coatings were analyzed by SEM, EDS, XRD, and XPS. The hardness of TiTaBN coatings were determined with microhardness tester. The friction and wear properties of the coatings were analyzed at different test athmospheres (humid air, distillated water, dry nitrogen and synthetic oil) by using pin-on-disc. Consequently, TiTaBN coatings deposited at the R8 coating parameters exhibited dense and a columnar structure. These coatings deposited at the R8 coating parameters contains TiN, TaN, TiB2 and BN phases and these coatings having ultra hardness (52.55GPa) demonstrated very high wear resistance at the different test athmospheres.

BP-19 Effect of Si+ kinetic energy on the physical properties of Ti-Si-N thin films deposited by RCBPLD
Luis Escobar-Alarcon, Enrique Camps, Veronica Medina (National Institute for Nuclear Research, Mexico); Dora Solis-Casados (Autonomus University of Mexico State, Mexico); Ivan Camps (Mexican National Autonomous University, Mexico)

Metal transition nitrides alloyed with C, Si or Al, have a wide range of applications, mainly in the metal-mechanical field as hard and low friction coatings. It is worth mentioning that the properties of these materials depend strongly on the alloying concentration and therefore a lot of work has been devoted in the last years to investigate deposition techniques capable to form such ternary nitrides with controlled composition. In a previous work, we proposed the so-called Reactive Crossed Beam Pulsed Laser Deposition (RCBPLD) technique as an alternative to produce ternary compounds with controlled composition; particularly, this technique was applied successfully to deposit Ti-C-N thin films controlling the C content. In this work, it is reported the use of the RCBPLD to prepare nanostructured TiSiN thin films. With this experimental configuration, the amount of silicon incorporated in the film is controlled in an easy way varying the mean Si+ kinetic energy. The film structure, mechanical properties, composition and surface morphology were investigated as a function of the Si+ kinetic energy. These properties were studied using the following characterization techniques: Raman spectroscopy, X-ray diffraction, nanoindentation, X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy. It was found that the Si content, which was varied from 1.6 to 3.5 at.%, depends, approximately linearly, on the silicon ion kinetic energy. Ti-Si-N films with hardness as high as 34.0 GPa, which is suitable for many mechanical applications, were obtained. The hardness was strongly affected by the silicon ion energy, and there exists an optimal energy value, and consequently a certain value of Si content at which the maximum hardness is reached. These results show that the properties of the deposited material are controlled partially by the Si+ kinetic used for thin film growing.

BP-20 The Role of Aluminium for the Nanostructure and Mechanical Properties of Sputtered Ti-B Films
Panos Epaminonda (University of Cyprus, Cyprus); Kyriaki Polychronopoulou (Northwestern University, US); Konrad Fadenberger (Robert Bosch GmbH, Germany); Mark Baker (University of Surrey, UK); Peter Gibson (Joint Research Centre, Italy); Adrian Leyland, Allan Matthews (University of Sheffield, UK); Paul Mayrhofer (Montanuniversität Leoben, Austria); Claus Rebholz (University of Cyprus, Cyprus)

TiB2 thin films have been studied extensively due to their outstanding properties (e.g. high hardness, high thermochemical stability), making them highly attractive for many applications in erosive, abrasive, corrosive and/or high-temperature environments. Despite their excellent properties, the usability and commercialisation of TiB2 films has been mainly hindered due to their brittleness and limited film-substrate adhesion, caused by the primarily strong covalent bonding in the hexagonal B network and the high compressive stresses developed in deposited films on various substrates. An effective route for improving adhesion and toughness in hard ceramic films is the introduction of ductile metal additions (e.g. Al) or layers, therefore modifying their bonding type and structure.

In this study, TixAlyB2 thin films (0.88≤ x ≤1.04; 0.12≤ y ≤0.31), with Al contents between 4.1-9.4 at.%, were deposited onto Si (100) and AISI 316 stainless steel substrates by simultaneous co-sputtering from TiAl and TiB2 targets in an argon discharge at 170˚C. The coating stoichiometry, relative phase composition, nanostructure, density and mechanical properties were determined using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Laser Acoustic Surface Waves (LAwave), in combination with nanoindentation measurements. It is shown that Al substitutes for Ti in stoichiometric closed-packed hexagonal nanocrystalline thin films with 4.1 at.% Al, having an average grain size of 2-3 nm. As the Al concentration is increased, the crystallinity, average TiB2 grain size, density, hardness and elastic modulus decreases from ~2-3 to 1 nm, 4.2 to 3.8 g/cm3, 32.9 to 20.6 GPa and 335 to 250 GPa, respectively, while the film adhesion increases. Density and elastic modulus from ab initio calculations are compared to experimental results. The elastic modulus values measured by nanoindentation are lower than the calculated ab initio data, attributable to the nanocrystalline nature of the deposited films.

BP-23 Mechanical Performance and Nanoscaled Deformation of Bias-Sputtered (AlCrTaTiZr)NCy Multi-component Coatings
Shao-Yi Lin, Shou-Yi Chang, Yi-Chung Huang, Fuh-Sheng Shieu (National Chung Hsing University, Taiwan)

This work develops (AlCrTaTiZr)NCy multi-component carbo-nitride films, with the incorporations of quinary metallic elements, nitrogen and carbon, as protective hard coatings by co-sputtering of AlCrTaTiZr alloy and graphite in an Ar/N2 mixed atmosphere with the application of different substrate biases. All the (AlCrTaTiZr)NCy films deposited at different conditions exhibited a simple face-centered cubic structure. As the applied substrate bias and graphite-target power increased, the deposited (AlCrTaTiZr)NCy coatings transformed from a large columnar structure with a (111) preferred orientation to a nanocrystalline or even near-amorphous structure. With increasing substrate bias and graphite-target power, the hardness and H/E ratio of the coatings increased from 18 GPa and 0.07, to much higher values of about 32 GPa and 0.12, respectively, attributed to the densification of the coatings, the introduction of covalent-like carbide bonds, the refinement of grains and the formation of nanocomposite structure. Because of the severe lattice distortions in the multi-component coatings caused by the addition of differently-sized atoms, the dominant deformation mechanism of the coatings was found to be the formation of stacking faults, rather than complete dislocations only.

BP-24 Effects of Substrate Temperature and Bias-Voltage on Mechanical Properties and Oxidation Resistance of TiAlYN Films
Norihiko Hattori (Keio University, Japan); Toshiyuki Takahashi (Yungaloy Corporation, Japan); Mayui Noborisaka, Takanori Mori, Mari Takahashi, Tetsuya Suzuki (Keio University, Japan)

It is well known that TiAlN films have been preferred in cutting tools for their mechanical properties and good oxidation resistance. However, many studies have reported that they oxidize over 800 ºC. The addition of another element into matrix is one of the techniques to improve the properties. In our previous researches, we reported on the effect of yttrium addition to TiAlN films and investigated the mechanical and thermal properties. It was concluded that the films with the yttrium content 2 at.% showed the highest hardness and excellent oxidation resistance up to 900ºC.

In this study, we synthesized Ti49Al49Y2N films changing substrate temperatures at 100ºC, 200ºC, 300ºC, 400ºC and bias-voltages at 50 V, 100 V, 200 V, 300 V and investigated their oxidation resistance and mechanical properties. The films were deposited on Si, WC-Co, and SUS304 substrates by the cathodic arc ion plating (AIP) method. The hardness and adhesion were analyzed by a micro-Vickers hardness tester and Rockwell hardness tester, respectively. For the evaluation of the oxidation resistance, X-ray diffraction (XRD) and glow discharge optical emission spectrometry (GDOES) were performed to identify oxide layers of the films annealing at 900ºC for 1 hour in air.

The hardness of all films doped yttrium increased, they were about 33 GPa. The films deposited at a substrate temperature of 200ºC showed an excellent substrate adhesion and oxidation resistance. The difference in hardness and oxidation resistance was not observed changing bias-voltage. The results demonstrated that Ti49Al49Y2N films deposited at bias voltage at 100 V and substrate temperature at 200ºC showed high hardness and the oxidation resistance keeping the adhesion strength.
BP-26 Characterization of laser ablation bismuth and iron oxide plasmas used for deposition of bismuth-iron-oxide thin films
Enrique Camps, Dagoberto Cardona, Luis Escobar-Alarcon (National Institute for Nuclear Research, Mexico); Sandra E. Rodil (Mexican National Autonomous University, Mexico)

Bismuth-Iron-Oxides (BFO) can be grown in five different phases, which can have very important multiferroic, magneto-optical and optoelectronic properties, making them attractive for different technological applications. The synthesis of these materials in the form of thin films has become quite difficult, being the laser ablation technique one of the most suitable. In the present work, it is proposed the simultaneous ablation of two targets (Bi and Fe2O3) in a reactive atmosphere (containing O2), in order to deposit BFO thin films with different compositions. Prior to deposition, the plasma parameters, such as, mean kinetic ion energy (Ep), plasma density (Np) and the type of excited species, were studied, in an attempt to correlate these parameters with the properties of the deposited BFO thin films. Deposition of the thin films was carried out at room temperature and the working pressure was varied in the range between 10 and 50 mTorr with an Ar/O2 =80/20 gas mixture. The iron oxide (FO) plasma parameters were kept constant at Ep (FO) = 100 eV and Np(FO) = 2 x 1013 cm-3, whilst the bismuth plasma parameters were varied in the range between 30 and 300 eV for the Ep(Bi) and 8 x 1011 – 9 x 1013 cm-3 for the Np(Bi). The optical emission spectroscopy (OES) showed that the most abundant excited species present in the plasmas were neutral Fe and neutral, once and three times ionized Bi. The deposited samples were characterized by Raman spectroscopy, X-Ray diffraction, EDS and RBS. The properties of the films are presented as a function of the plasma parameters.

BP-27 A study of W/DLC/WSC composite films fabricated by magnetron sputtering method
Mingjiang Dai, Chunbei Wei, Songsheng Lin, Huijun Hou, Kesong Zhou (Guangdong General Research Institute of Industrial Technology, China)
WS2 is well known for its solid lubricating behavior in industry applications. However, it is sensitive to environmental atmosphere. In humid ambient air, WS2 gets easily oxidized, resulting in the deterioration of its tribological properties. Moreover, another problem of the sputtered WS2 films is their very low adhesion to the substrate, which lead in most cases to poor wear behaviour. In order to improve the properties of WS2 film in humid air conditions, W/DLC/WSC composite films have been fabricated by magnetron sputtering method. The properties of composite films, as well as the influence of C content in the WSC top layers were researched. The morphology and microstructure of the composite films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Vickers microhardness tests were carried out to determine the hardness of composite films. Scratch tests were performed to study the adhesion of the films to the cemented carbide substrate. The tribological behavior was investigated using a ball-on-disk tribometer in humid air. The results show that the composite films exhibit dense and featureless in appearance. None C or WS2 peaks have been observed in the spectrum of X-ray diffraction (XRD). Thereby, amorphous or nanocrystal structure has been obtained according to the SEM and XRD results. The hardness of composite films can be enhanced obviously and it increases with increasing the C content. Compared to the pure WSx film, W/DLC/WSC gradational structure can improve the adhesion of films effectively and the maximal critical load of the composite film reaches 62N. Though the friction coefficient of the pure WSx film (about 0.1) is lower than that of the composite films (0.15~0.25), the wear life of composite films are much longer owning to their higher hardness and better adhesion to the substrate.
BP-28 Comparison of the wear characteristics of TIN Coating with Manganese Phosphate Coating.
Ilaiyavel Sivakumaran, Venkatesan Alangaram (Sri Venkateswara College of Engineering, India)

Manganese Phosphate is an Industrial coating used to reduce friction and improve lubrication in sliding components. In this study, the tribology behavior of TIN (which as produce both PVD and CVD ) Manganese Phosphate with Molybdenum disulphide (MoS2) coated AISID2 steels was investigated. The Surface morphology of manganese phosphate coatings was examined by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) .The wear tests were performed in a pin on disk apparatus as per ASTM G-99 Standard. The wear resistances of the coated steel were evaluated through pin on disc test using a sliding velocity of 3.3 m/s under Constant load of 50 N and controlled condition of temperature and humidity. The Coefficient of friction and wear loss were evaluated. The temperature rise after 15 min and 30 min were recorded for each load. Wear pattern of TIN, Manganese Phosphate with Molybdenum disulphide (MoS2) coated pins were captured using Scanning Electron Microscope (SEM). Based on the results of the wear test the manganese phosphate with Molybdenum disulphide (MoS2) coating exhibited the lowest coefficient of friction and the lowest wear loss under 50 N load.

BP-29 Exotic mechanical properties of Cu-doped nano-columnar DLC coating
Satoru Yukawa, Tatsuhiko Aizawa (Shibaura Institute of Technology, Japan)

Diamond like carbon (DLC) coating has grown up to be a common way to improve the surface properties of dies and punches in dry stamping, by its high wear resistance and low friction coefficient. Aiming at its applications to an oxide-glass stamping mold-dies or a protective coating for MEMS/NEMS, high thermal stability and elasticity are much required. In fact, the stability above the glass-transition temperature of oxide glass and nano-scaled dimensional guaranty are needed in the mold-stamping process of collective lens for solar panel. Nano-columnar DLC coating is suitable for this application because of the high durability and metallic doping is effective to improve the thermal stability at elevated temperature.

Cu-doped DLC coating was prepared on silicon wafer by RF-sputtering with co-doping method. Deposited film was subjected to low energy electron beam (EB) irradiation. Nano-columnar structure with copper, which segregates into the grain boundary, is formed. The size of columns ranges around 20 nm. Raman spectroscopy is utilized to describe the bonding state and structure. Obtained spectrum of Cu-doped EB irradiated film is deconvoluted into two peaks pairs (D1:G1, D2:G2) . Calculated I(D1)/I(G1) and I(D2)/I(G2) are 2.11 and 0.30, respectively. D1 and G1 correspond to initial amorphous carbon matrix: its in-plain correlation length (La) becomes 2 nm. La ( D2:G2) is estimated 15 nm and it nearly equals to average of the measured diameter of columns. That is, graphitization takes place in the inter-columnar region and vertically aligned graphitic network is embedded in the disordered amorphous carbon matrix. Compared with undoped sample after EB irradiation, Cu-doped sample is much more graphitized: I(D2)/I(G2) for undoped is 0.46. Hardness of the samples, Cu-doped after EB, undoped as-deposited and undoped after EB, obtained by nano-indentation are 1166, 1150 and 1071, respectively. Cu-doped sample shows a great elastic recovery and it is reversible up to 12% of the film thickness. This hardening and elasticity attribute to segregation of copper and graphitization in inter-columnar region.
BP-30 A Fem Supported Method for the Fast Determination of Nanoindenter’s Tip Geometrical Deviations
Konstantinos-Dionysios Bouzakis, Maria Pappa, Georgios Maliaris, N. (N.) Michailidis (Aristoteles University of Thessaloniki; Fraunhofer Project Center Coatings in Manufacturing (PCCM), Greece)

Nanoindentation is an effective technique for determining mechanical properties of bulk materials and thin films. Prevailing measurement uncertainties in nanoindentations by Vickers or Berkovich diamond pyramids are commonly caused by manufacturing imperfections of the indenter’s side angles and tip sharpness. Moreover, the tip geometry changes during the indenter lifetime, due to diamond wear.

The present paper deals with a fast method for estimating diamond indenters’ tip nano and micro geometry. On one hand, this method is based on a combination of nanoindentations on Si(100) used as reference material and on the other hand, on FEM supported calculations of Martens hardness. The hardness calculations are conducted using equivalent indenter tip geometry with geometrical characteristics which may vary for a specific set of parameters, describing the real indenter with manufacturing imperfections. These parameters are varied in successive iterations until the calculated hardness converges with that of the reference material.

For a quick determination of these parameters, the software package “TIDE” (TΙp Deviations Estimation) has been developed. “TIDE” is based on numerous FEM supported simulation’s results of nanoindentations onto the reference material varying the indenter tip geometry. By this software package, a quick prediction of nanoindenters’ tip equivalent geometry is facilitated, also for anticipating changes due to wear of the diamond over time.

KEYWORDS: Nanoindentation, tip, imperfections, wear

BP-31 An analysis of the effect of local environments on vacancy formation and diffusion energy barriers in Ti0.5Al0.5N alloy
Ferenc Tasnádi, Magnus Odén, Igor Abrikosov (Linköping University, Sweden)

Microstructure analysis has attracted high interest in hard coating developments as often the microstructure has a decisive impact on the hardness of materials [1]. For example, the isostructural spinodal decomposition results in hardness enhancement in TiAlN. Modeling microstructure evaluation via diffusion requires not only energetic, mechanical but also kinetic parameters of the materials. Here we present results on vacancy, divacancy formation and migration in Ti0.5Al0.5N alloy using first principles density functional theory calculations. We pay special attention to the analysis of the impact of local environments.

[1] P. H. Mayrhofer, C. Mitterer, L. Hultman and H. Clemens, Prog. Mat. Sci. 51, 1032 (2005).

BP-32 First-principles study of the local environment effects on surface diffusion in multicomponent nitrides
Christopher Tholander, Ferenc Tasnádi, Björn Alling, Lars Hultman (Linköping University, Sweden)

Growth of multicomponent nitride thin films is typically performed under kinetically limited conditions. Thus, the study of surface diffusion is one key to understanding behavior such as texture development and clustering during crystal growth. An earlier study of diffusion on TiN(001) and (111) surfaces [1] has shown that there is a large difference in diffusivity of adatoms on different surface directions, which greatly influences the preferred growth direction. We present results from first-principle studies using the nudged elastic band technique to calculate the energy barriers on low index crystal surfaces. By introducing different metal atoms and clusters in the surface of TiN and calculating the changes in the surface energy barriers, we show the effects on surface diffusion due to the change in the local environment. For example we show that the introduction of configurational disorder in Ti0.5Al0.5N(001) slow down the Ti adatom diffusion as compared to the pure TiN(001) case.

[1] D. Gall, S. Kodambaka, M. A. Wall, I. Petrov, and J. E. Greene, J. Appl. Phys. 93, 9086 (2003)

BP-33 Effects of electroless Ni and PVD-TiAlZrN duplex coatings on corrosion and erosion behavior of ductile iron
Cheng-Hsun Hsu, Kuan-Hao Huang, Yin-Hwa Cheng (Tatung University, Taiwan); C.K. Lin (Feng Chia University, Taiwan); K.L. Ou (Taipei Medical University, Taiwan)

This study utilized electroless nickel (EN) plating and cathodic arc evaporation (CAE) technologies to deposit the protective coatings onto ductile iron substrates. Polarization corrosion tests were performed in 3.5% sodium chloride. The erosion tests were also carried out using Al2O3 particles (~177 mm in size and Mohr 7 scale) of about 5 g, and then surface morphologies of the eroded specimens were observed. To further understand the coating effects on both the corrosive and erosive behaviors of ductile iron, coating structure, morphology, and adhesion were analyzed using XRD, SEM, and Rockwell C indentation, respectively. The results showed that EN coating exhibited an amorphous structure, while TiAlZrN had a multilayered type. With regard to both the corrosion resistance and erosion resistance, the TiAlZrN/EN duplex coated specimens performed better than did the uncoated and monolithic EN or TiAlZrN ones.

BP-35 Structure and properties of TiBCN coatings synthesized using unbalanced magnetron sputtering
Ching-Hui Hsieh, Chia-Hang Tsai, Wei-Yu Ho (Department of Materials Science and Engineering, MingDao University, Taiwan); Cheng-Hsun Hsu (Department of Materials Science and Engineering, Tatung University, Taiwan); Chen-An Lin (Department of Materials Science and Engineering, MingDao University, Taiwan); Chien-Liang Lin (Department of Electro-Optical and Energy Engineering, MingDao University, Taiwan)
The development of multifunctional coatings based on nanocomposite and multilayers was design to meet various severe corrosion, oxidation, and wear environmental conditions. Nanocomposite coatings are usually formed from ternary or higher order systems which are supersaturated or metastable solid solutions or comprise at least two immiscible phases. TiBCN coating system was one of the promising nanocomposite coating systems exhibiting super hardness, good tribological properties, and high oxidation and corrosion resistance. TiBCN coating have been successfully synthesized by chemical vapor deposition (CVD), electron beam physical vapor deposition (EBPVD), and more commonly by dc magnetron sputtering. In the present study, TiBCN nanocomposite coatings were deposited from TiB2 and Ti dual targets using a unbalanced magnetron sputter system operated with fixed nitrogen flow and different C2H2 flows. The effects of the carbon content on the phases, microstructure, mechanical and tribological properties of TiBCN coatings were investigated. It is shown that with the different carbon content in the coatings the microstructures of TiBCN can be tailored to TiBN, TiBCN and TiBCN/Carbon duplex layers. The coated samples were characterised with the following techniques: nano-indentation (hardness), ball-on-disc (wear and friction), scratch test (adhesion), scanning electron microscopy and Raman spectroscopy (microstructure) tests.
BP-36 Low Temperature Plasma Nitriding of F51 Duplex Stainless Steel
André Tschiptschin, LuisBernardo Varela (University of São Paulo, Brazil); Carlos Pinedo (Heat Tech Technology for Heat Treatment and Surface Engineering Ltd, Brazil)

In this work an AISI F51 duplex stainless steel was DC-Plasma nitrided (PN) at 400oC, during 20 hours in a 75% N2 + 25% H2 atmosphere. A modulated plasma nitrided layer formed on the specimen´s surface: the nitrided layer observed on the ferritic regions was 3 µm thick, while the nitrided layer formed on the austenitic regions of the microstructure was ~2 µm thick. Very fine martensite needles were observed on the ferritic regions, while expanded austenite layer (ΥN) formed on the austenitic regions. The nitrogen content of the nitrided layer was estimated from X-ray diffraction measurements and WDX as being ~3.4 to 4.4 wt % N, leading to colossal supersaturation and strong hardening of the surface, up to 1350 HV. The 400 ºC plasma nitrided layer did not impair the corrosion resistance of the duplex stainless steel. These results are discussed based on the hypothesis that, during nitriding, ferrite transforms at first to austenite and then to expanded austenite, due to nitrogen pickup. The expanded austenite formed on ferrite regions transforms to martensite, under stresses developed during the formation of expanded austenite in the neighboring austenite grains.

Keywords: Plasma nitriding, Duplex stainless steel, Expanded austenite, Martensite

BP-37 Residual stress on nanocomposite thin films using sin2Ψ method
Giovanni Ramírez, Sandra Rodil, José G. González-Reyes (Universidad Nacional Autónoma de México - Instituto de Investigaciones en Materiales, Mexico)

Residual stress on thin films can be significantly high, sometimes as large as several gigapascals and they can be either compressive or tensile. For the super-hard coatings, such as metal nitrides or carbides, the hardness and the compressive stress are strongly correlated; in such a way that the high hardness values are usually obtained for highly strained films. This correlation imposes some limitations in both the thickness of the films and their use for high temperature applications. In this work, we have produced nanocomposite thin films of tantalum nitride (TaN) and niobium nitride (NbN) nanocrystals embedded in amorphous silicon nitride (SiNx) phase. The films were deposited using two magnetrons (pure metal and silicon) and the silicon content on the films was varied by increasing the radio frequency power applied to the Si-target, while the other deposition conditions remained fixed. In both cases, the results showed that the hardness increased as the Si content increased from 0 to 5-6 at%, but further Si incorporation resulted in a decrease in the hardness.

The aim of the present work was to study the possible correlations between the residual stress, the silicon content and the hardness of the films. The residual stress was determined the lattice strain method using X-ray diffraction. The sin^2(psi) method was used to determine the stress tensor. The results showed that the films present a triaxial stress state with compressive components in the plane normal to the growth direction and shear components. From this analysis it was demonstrated that even for the nanocomposite films, the maximum hardness films also showed the highest stresses. Stress in the direction x and y are compressive and equivalent in magnitude so that is not a change or stress gradient in the direction perpendicular plane to the film growth. On the other hand, the stress in the z direction (perpendicular to the growth of the film) was tensile.

We concluded that the described method commonly used to study bulk materials can be used to calculate the stress tensor in hard nanocomposite coatings. The results obtained indicated that the hardness was directly related to the stress; larger hardness values were obtained for the samples with the higher stress.

Acknowledgements: We wish to acknowledge the financial support from DGAPA-UNAM IN103910. G. Ramírez acknowledges CONACYT for his PhD scholarship.

BP-38 Stress signature of an amorphous- to- crystalline transition into the β-phase during Ta thin film growth on Si.
Amélie Fillon, Jonathan Colin, Caroline Szala, Anny Michel, Gregory Abadias, Christiane Jaouen (Institut P' - Universite de Poitiers, France)

Tantalum is a refractory metal with low electrical resistivity. Interest in the electrical properties of Ta thin films have been stimulated by its potential applications in electronic devices. Bulk Ta has a bcc structure, known as the α-phase. However, during thin film growth, the metastable tetragonal β-phase is commonly formed, especially on Si substrates. β-Ta has a higher resistivity, is also harder and more brittle than α-Ta. Role of impurities, defect concentration and stress state have often been reported. Nonetheless, the preferential formation of the β-phase onto Si substrates is not fully understood.

To address the impact of growth conditions on physical properties of thin sputtered Ta films, we present results obtained by combining highly sensitive in-situ stress measurements by the substrate curvature technique and ex-situ structural investigations (XRD and HRTEM). Thin films of Ta were grown at room temperature on an amorphous Si layer, or on Si substrates, using magnetron sputter-deposition under Ar atmosphere. A structural change occurring in the nanometric range (~ 3-4 nm) is clearly identified, from both the real-time stress evolutions and ex-situ structural characterizations, which is attributed to a polymorphic crystallization of an amorphous film, initially stabilized by a minimization of the interface energy. The amorphous to β-crystalline transformation is accompanied by the development of an intrinsic growth stress, with a steady-state component ranging from a tensile state to a compressive one as a function of processing parameters (Ar working pressure : 0.1 – 0.8 Pa, substrate bias voltage : 0 – 100V). Finally, these results suggest that the nucleation into the β-phase would be favoured by similar specific volumes of the two metastable amorphous-Ta and β-Ta phases, whereas the β-phase growth at larger thicknesses would be explained by the weak difference between the Gibbs energies of α-Ta and β-Ta.

BP-39 Influence of Bias Voltage on Residual Stresses and Mechanical Properties of Multicomponent TiSiCrAlN Coatings
Yin-Yu Chang (National Formosa University, Taiwan); Ching-Yu Tsai (MingDao University, Taiwan)
The extension of the tool life is a considerable goal for cutting and forming tools. Therefore the industry is interested to improve the mechanical performance for such tools. Transition metal nitrides, such as TiSiN and CrAlN, have been used recently as protective hard coatings due to their excellent tribological properties. In this study, TiSiN, CrAlN and multicomponent TiSiCrAlN coatings with different alloy contents were synthesized by cathodic-arc evaporation with plasma enhanced duct equipment. The multicomponent TiSiCrAlN coatings have a high potential as hard and tough coating to improve the tribological behavior of cutting and forming tool surfaces. TiSi and CrAl alloy cathodes were used for the deposition of TiSiCrAlN coatings. During the coating process of multicomponent TiSiCrAlN, TiN was deposited as an interlayer. With different cathode current ratios (I[TiSi]/I[CrAl]), the deposited TiSiCrAlN coatings possessed different chemical contents. Due to the absence of adhesive and cohesive damage processes by the residual stress behavior in the layer near the substrate area, it is critical to measure residual stresses in order to increase tribological resistance. X-ray diffractometry was performed for phase identification using a PANalytical X’pert Pro diffractometer with a high resolution ψ goniometer and Cu radiation in both glancing angle and high-angle configurations. In addition to the phase analysis, the residual stress measurements were also investigated by means of x-ray diffractometry. An experimental method with a grazing-incidence diffraction geometry was used in order to enhance the irradiation volume of thin film samples. The microstructure of the deposited coatings was investigated by a field emission gun high resolution transmission electron microscope (FEG-HRTEM, FEI Tecnai G2 20 S-Twin), equipped with an energy-dispersive x-ray analysis spectrometer (EDS), operated at 200 keV for high-resolution imaging. Mechanical properties, such as the hardness and elastic modulus, were measured by means of nanoindention. To evaluate the impact resistance of the deposited coatings, an impact test was performed using a cyclic loading device.
BP-40 Effect of degree of ionization on preferred orientation and properties of TiN thin films deposited by high power impluse magnetron sputtering
Cheng-Yang Chen, Ge-Ping Yu (National Tsing Hua University, Taiwan); Jin-Yu Wu (Institute of Nuclear Energy Reserach, Taiwan); Jia-Hong Huang (National Tsing Hua University, Taiwan)
Due to its high hardness and low electric resistivity, TiN has been widely used as protective coatings on cutting tools and as diffusion barrier in microelectronic devices. The preferred orientation of TiN thin film is one of the major parameters that may affect the film properties. Therefore, many mechanisms have been proposed to explain the evolution of the preferred orientation of TiN deposited at different conditions. Most TiN specimens in the previous studies were prepared using dc magnetron sputtering. Few studies were performed at highly ionized condition to investigate the effect of ionization on the preferred orientation and the corresponding TiN thin film properties. Recently, high power impulse magnetron sputtering (HIPIMS) has attracted considerable interests in industrial applications. By using power supplies that are able to provide the target with very high pulsing power density within several microseconds while maintain the average target power density similar to dcMS, HIPIMS can generate an ultra-dense plasma (1013~1014 ions/cm3) where the sputtered atoms are highly ionized (70%~100%). As a result, this highly ionized plasma can be used to bombard the substrate, deliver energy to adatoms to facilitate their migration, and even manipulate thin film preferred orientation to tailor the film properties. The purpose of this research was in an attempt to control the preferred orientation of TiN thin film using HIPIMS with different degree of ionization. In this study, by varying pulse shape, or nitrogen flow rate to control the degree of ionization of HIPIMS, TiN thin film was deposited on Si wafer. Subsequently, the microstructure, compositions, and mechanical properties of the TiN thin film were fully characterized. The preferred orientation was characterized by X-ray diffraction. The microstructure and to measure thin film thickness was observed by SEM. The composition of the film was determined by XPS and RBS. Nanoindentation and four-point probe were utilized to measure the film hardness and the electric resistivity, respectively. The residual stress of the TiN film was measured by optical laser curvature method. The results showed that the preferred orientation of thin film varied with the degree of ionization. The mechanical properties and resistivity of the thin film were also sensitive to the degree of ionization. However, since the thin film was extensively bombarded by ion under the deposition conditions, the TiN film possessed very high residual stress. The experimental results indicated that by adjusting the degree of ionization of plasma, the thin film preferred orientation and the accompanying properties can be controlled.
BP-41 Microstructures and mechanical properties of titanium carbide coating obtained by Thermo-reactive deposition process
Xue-shuang Fan, Zhi-gang Yang, Chi Zhang (Tsinghua University, China)

Thermo-reactive deposition/diffusion (TRD) process is a method used to prepare hard, wear-resistant coatings of carbides, nitrides, or carbonitrides on steels. In this study, carbide coating was tried to deposit on T10 steels by duplex treatment. The steel substrate was immersed in a molten salt bath consisting of vanadium then in a molten salt bath consisting of titanium at 1000 oC. The obtained coatings were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and X-ray diffraction (XRD). The results showed that the coating obtained from the duplex treatment was composed of two distinct layers. The outer layer was titanium carbide and the inner layer was vanadium carbide. The substrate /vanadium carbide coating interface and the vanadium carbide coating/ titanium carbide coating interface is distinct and without transition zone. The micro-hardness, scratch and pin-on-disk wear tests were conducted to evaluate the mechanical properties. The results showed the hardness of the duplex coating is higher than the vanadium carbide single layer. And the duplex coating exhibited excellent adhesive strength and outstanding wear resistance.

BP-42 Enhanced Glow Discharge Plasma Immersion Ion Implantation Using an Insulated Tube
Qiu Yuan Lu, Paul Chu (City University of Hong Kong, Hong Kong Special Administrative Region of China); Liu He Li (City University of Hong Kong; Beijing University of Aeronautics and Astronautics, Beijing, China); Ricky K. Y. Fu (City University of Hong Kong, Hong Kong Special Administrative Region of China)

Enhanced glow discharge plasma immersion ion implantation (EGD-PIII) conducted using a small pointed hollow anode and large tube cathode has certain advantages over conventional plasma immersion ion implantation (PIII). In EGD-PIII, the plasma is produced by self glow discharge induced by the negative high voltage applied to the sample. The plasma distribution measured by Langmuir probe measurements discloses that the electron density is quite uniform in the vicinity of the negatively biased substrate. Although the impact energy and ion implantation fluence have been demonstrated to be better in EGD-PIII than those in conventional PIII, lateral non-uniformity in the ion fluence is observed during hydrogen implantation into a silicon wafer and the ion focusing effect depends on the plasma density. An insulated tube placed between the chamber and gas inlet is employed to increase the interaction path for electrons and neutrals, and theoretical and experimental studies reveal that the insulated tube can enhance ionization of plasma gases with low ionization efficiency such as hydrogen. However, the implantation current is observed to increase sharply at a certain pressure when the plasma gas consists of diatomic molecules. In this work, we experimentally investigate the implantation current characteristics in EGD-PIII. The plasma potential is measured to investigate the discharge phenomenon and X-ray photoelectron spectroscopy (XPS) is conducted to corroborate the findings.

BP-43 Electrical transport properties in ZrN-SiNx-ZrN structures investigated by I-V measurements
David Oezer, SilvioC. Sandu (EPFL, Switzerland); Rosendo Sanjines (Ecole Polytechnique Fédérale de Lausanne, Switzerland)
Nanocomposite thin films based on polycrystalline transition metal nitride (MeN, Me = Ti, Cr, Zr, …), in which the metallic MeN crystallites are embedded in an amorphous silicon nitride matrix, are considered as interesting materials due to their rich variety of physical properties, such as high hardness and improved thermal and chemical stability. The mechanical, optical and electrical properties are strongly linked to the architecture of the silicon nitride tissue phase at the grain boundaries. According to our best knowledge the local chemical composition and the thickness of the grain boundaries have never been probed directly so far. However the interpretation of the temperature dependent electrical resistivity data in the frame work of the grain boundary scattering model combined with structural and chemical analyses allows to correlate the evolution of the silicon nitride coverage layer to the electron grain boundary transmission probability. In order to investigate the mechanism of electrical conduction through single grain boundaries, we have investigated the transverse electric transport through well defined ZrNy/SiNx/ZrNy multilayers with varying SiNx interlayer thicknesses and chemical compositions by means of I-V characteristic curves. At room temperature, depending on the SiNx thickness linear I-V and symmetric nonlinear I-V characteristics are observed. On the bases of standard models for M-I-M such as the Poole-Frenkel and Tunneling models, we will discuss the applicability of our results to the interpretation of the electric conduction in “real” nanocomposite MeN/SiNx systems.
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