ICMCTF1999 Session BP: BP Posters

Tuesday, April 13, 1999 5:00 PM in Room Atlas Foyer
Tuesday Afternoon

Time Period TuP Sessions | Topic B Sessions | Time Periods | Topics | ICMCTF1999 Schedule

BP-1 Mathematical Modeling of a Carburizing Process of a SAE 8620H Steel
H. Jiménez (Siderúrgica del Orinoco, C. A., Venezuela); M.H. Staia, E.S. Puchi (Central University of Venezuela)
A SAE 8620H steel has been carburized in a pack cementation process using a solid mixture of metallurgical coke with additions of BaCO3 and Na2CO3. The influence of temperature, exposure time and type of mixture on the rate of carbon diffusion into the matrix has been correlated with the microhardness values conducted on the cross section of the test samples. The qualitative profile of carbon concentration was determined by means of EDS techniques. The carbon concentration profiles determined experimentally were compared with those calculated theoretically employing a diffusion model based on Fick’s second law. It has been concluded that the theoretical model describes satisfactorily the carbon concentration profiles. Therefore, the diffusion coefficient can be considered independent of carbon concentration and the carbon potential at the surface can be considered constant. The mixture employed for the cementation process has been found to be appropriate in order to achieve the required carbon concentration profile and surface hardness of the matrix.
BP-2 Mechanical and Tribological Properties of Tungsten Carbide Sputtered Coatings
J. Esteve (Universitat de Barcelona, Spain); G. Zambrano (Universidad del Valle, Colombia); C. Rincon (Universidad Autonoma de Occidente, Colombia); E. Martinez (Universitat de Barcelona, Catalunya-Spain); H. Galindo (Universidad de los Andes, Venezuela); P. Prieto (Universidad del Valle, Colombia)
Tungsten Carbide (WC) hard coatings have been obtained on steel substrates by r.f. magnetron sputtering process. Two layer coatings have been deposited in order to improve adhesion on steel. The first layer is pure tungsten metal and was obtained by sputtering a tungsten target in Ar gas. The second layer is WC and was obtained by reactive sputtering of the tungsten target in Ar and methane gas or alternatively by sputtering of a sintered WC target in Ar gas. The structure of the films have been characterized by X-ray Diffraction Spectroscopy (XDR), Auger Electron Microscopy (AES) and Reflection Absorption Infrared Spectroscopy (RAIRS). XRD, AES and RAIRS results confirm that the W2C and WC phases content in the film, depends on the substrate temperature and the reactive sputtering gas composition. Films microhardness were measured by the dynamical nanoindentation method and coatings adhesion by the micro scratch method. Measurement results show that coatings with large hardness values can be prepared at a relative low temperature and that good adhesion on steel is achieved with the two layer coating. Friction and wear measurements performed on these films showed a noticeable dependence of these tribological properties on their phase composition.
BP-3 Further Developments of a Novel Structure Zone Model Relating to the Closed-Field Unbalanced Magnetron Sputtering System
P.J. Kelly, J. O'Brien, R.D. Arnell (University of Salford, UK)
The closed-field unbalanced magnetron sputtering (CFUBMS) system is recognised as a technique capable of producing high quality, fully dense coating structures. Indeed, systematic studies of the CFUBMS system at Salford have shown that, under typical operating conditions, porous coating structures are excluded. These studies cumulated in the development of a structure zone model relating to the CFUBMS system (PJ Kelly and RD Arnell, J.Vac.Sci.Technol., A16(5) 1998, 2858-2869). However, other investigations at Salford into the formation of high surface area, chemically reactive coatings have shown that highly porous structures can be formed under very specific conditions. The deposition and analysis of such structures is, therefore, discussed in this paper. The results of this study have allowed further developments to be made to the recently proposed structure zone model. Most significantly, the low energy regime of the model has been expanded with the addition of a porous columnar zone 1-type region, not previously included.
BP-4 Microstructure and Property Changes Caused by Diffusion During CVD-Coating of Steels
O. Kessler, F. Hoffmann, P. Mayr (Stiftung Institut f. Werkstofftechnik, Germany)
During CVD-coating of steels interdiffusion between substrate and coating occurs. Especially carbon diffuses from the substrate to the coating. This diffusion influences the microstructures and properties of substrate and coating in the interface. Influencing parameters are coating atmosphere, temperature, time and pressure. These coating parameters and the composition of steel substrates were investigated systematically to optimize the properties of coating/substrate-compounds. The tool and carbon steels X40CrMoV5-1 (AISI H13), X100CrMoV5-1 (AISI A2), Ck45 (AISI 1045) and 100V1 (approx. AISI 1095) were coated by high temperature HT-CVD TiN, low pressure LP-CVD TiN and moderate temperature MT-CVD TiCN. Substrate and coating microstructures were examined in taper sections by light microscopy. Chemical compositions of coatings and substrates were measured by glow discharge optical spectroscopy (GDOS) and electron probe microanalysis (EPMA). Further the substrate hardness was investigated in the taper sections. Low coating pressures combined with high temperatures and high carbon activities of the substrates promoted the diffusion process. The LP-CVD TiN-deposition on the substrates Ck45 and 100V1 caused the strongest carbon diffusion from the substrates to the coatings. In the quench hardened substrates Ck45 and 100V1 the substrate alterations caused a pearlite structure instead of martensite and a hardness drop towards the interface.
BP-5 Vacuum arc Deposition of Conductive Wear Resistant Coatings on Polymer Substrates
V.N. Zhitomirsky (Tel-Aviv University, Israel); I. Grimberg (Technion - Israel Institute of Technology, Israel); M. Joseph (University of Hull, UK); R.L. Boxman (Tel-Aviv University, Israel); A. Matthews (University of Hull, UK); B.Z. Weiss (Technion - Israel Institute of Technology, Israel)

Thin conductive wear resistant metal/ceramic coatings were deposited onto polysulfone S2010 substrates using a triple-cathode vacuum arc plasma source connected to a magnetized plasma duct. Various combinations of two-layer coatings having an inner metallic conductive layer of Ti, Zr, Cu, Ag or Al attached to the plastic, and an external wear resistant layer of TiN or ZrN, were studied and evaluated. The deposition parameters (arc current, magnetic field strengths, deposition time) were optimized (1) to obtain the required deposition rate and coating thickness, and (2) to obtain good adhesion of the coating to the substrate at low temperature.

It was shown that bi-layer Ti/TiN and Ti/ZrN coatings had good adhesion to the substrate and low wear rate, but their electrical resistivity was high (3-6.6 Ω/square). Cu, Ag and Al metal sub-layers had a superior adhesion to the polymer substrate and low electrical resistivity (less then 0.1 Ω/square). However, the deposition of TiN layer on Ag caused immediate coating delamination from the substrate. Similar behavior was observed also with the Ag/Ti/TiN combination. In the case of Ag/ZrN coatings, which initially possessed good adhesion to the substrate, cracking and delamination of ZrN at the Ag/ZrN interface was observed after some time (1-7 days), while the Ag layer remained adherent to the substrate. In the cases of Cu/TiN and Cu/ZrN coatings, the nitride layers had poor adhesion to the Cu layer. The best results were obtained for Al/ZrN coatings, which had low resistivity (0.08-0.11 Ω/square) with good adhesion of the Al layer to the substrate and of the nitride layer to Al.

BP-7 Preparation of TiC Films by Alternate Deposition of Ti and C Layers Using a Dual Magnetron Sputtering Source
E. Kusano, A. Satoh, N. Kikuchi, A. Kinbara (Kanazawa Institute of Technology, Japan)
Titanium carbide (TiC) films have been prepared by alternately depositing thin Ti and C layers on aluminoborosilicate glass substrate by magnetron sputtering. The apparatus used in the experiment was a dual-cathode sputtering machine with a carrousel type substrate holder. By rotating the substrate holder, a thin Ti layer of about 0.1nm(at a rotation rate of 30rpm) and a thin C layer of about 0.15nm were alternately deposited on the substrate. The Ti/C compositional ratios of films were controlled by changing flux ratio (layer thickness ratio) of the Ti and C sources. This allowed preparing films of Ti, TiC, and C. The composition, structure, and hardness of the deposited films were estimated as a function of the source C/Ti flux ratio. The results of X-ray photoelectron spectroscopy showed that the film composition changed Ti:C=1:0 to 0:1 continuously and that some oxygen was incorporated as an impurity for low C/Ti ratios. The X-ray diffraction measurement results showed that the film structure changes from a-Ti (obtained for a C/Ti flux ratio of <0.1), fcc-TiC(obtained for C/Ti ratios of 0.1 to unity) to an amorphous structure(obtained for flux C/Ti ratios of > unity) and that the lattice spacing increased continuously in the C/Ti flux ratio region of 0 to unity. The maximum microhardness of about 16GPa was obtained for the film deposited at the flux ratio of unity. In the abrasive wear resistance test, higher abrasive resistance was observed for the films deposited with the C/Ti flux ratios of more than 0.3. The transition of the film structure and composition well elucidates the film hardness and abrasive wear behavior.
BP-8 Synthesis of A-Axis-Oriented AlN Film by Shielded Reactive Vacuum Arc Deposition Method
H. Takikawa, N. Kawakami, T. Sakakibara (Toyohashi University of Technology, Japan)
Aluminum nitride (AlN) thin films were prepared by a conventional reactive vacuum arc deposition method and by a shielded vacuum arc deposition method. In latter case, a metal plate was located between an Al cathode and substrates as a shield plate in order to avoid the deposition of the macro droplets emitted from cathode spot to the film. Substrates used were silicate glass, molybdenum, silicon, and quarts. No bias and no additional heat were applied to the substrates. The following properties of the film were measured; thickness for obtaining deposition rate, surface morphology with a scanning electron microscope and optical microscope, crystalline structure by X-ray diffraction analysis, and transmittance with a UV-VIS spectrometer. As a result, the deposition rate for the shielded arc process decreased by half compared to that for the conventional process. However, the films prepared by the shielded arc process were not peeled off from the substrate and significantly transparent without macro droplets, while the films prepared by the conventional process were peeled off and were not transparent and also there were many macro droplets on the film. X-ray diffraction analysis revealed that the films prepared by the conventional process oriented to c-axis and contained the Al, whereas the films prepared by the shielded arc process oriented to a-axis and Al peak were not detected from the film. Optical and mechanical properties, such as refractive index, extinction coefficient, microhardness, and elastic modulus, of the a-axis-oriented film as a function of process gas pressure are presenting as well.
BP-9 Improvement of Interfacial Integrity of TiAlN Hard Coatings Deposited on High Speed Steel Cutting Tools
D.Y. Wang, C.L. Chang, K.W. Wong (National Chung Hsing University, Taiwan, ROC); Y.C. Lee (National Dong Hwa University, Taiwan, ROC); W.Y. Ho (Surftech Corp., Taiwan, ROC)
Due to the improved microhardness and high temperature resistance, the advanced TiAlN hard coating has been applied successfully to carbide tools for high speed machining. When applied to high speed steel cutting tools, however, poor tribological performance occurred due to adhesion problems at the interface. In this study, a series of multilayered interfaces consisting of Ti, TiN, and/or (Ti,Al)N were investigated to improve the adhesion strength of TiAlN to high speed steel substrates. Deposition of both interlayer and TiAlN films was conducted sequentially in a single batch process. Cathodic arc evaporation was selected as the deposition process for its superior plasma intensity and the flexibility of multiple targets arrangement. Microstructure and tribological properties were analyzed by SEM/EDS, XRD, and Tribo-testers. Results indicated that a combination of Ti and TiN interlayer could provide an adhesion strength of 70N between TiAlN and M2 substrates. The tribological performance of TiAlN thin film on high speed steel cutting tools is significantly improved.
BP-10 Effect of Magnetic Field Structure Near Cathode on the Arc Spot Stability of Filtered Vaccum Arc Source of Graphite
J.-K. Kim, K.-H. Cheong (Seoul National University, Korea); K.-R. Lee (Korea Institute of Science and Technology, Korea)
Amorphic diamond films deposited by filtered vacuum arc (FVA) method has been attracted much attention due to their superior mechanical and optical properties. However, it is well known that the instability of the arc spot limited the continuous operation of the FVA source, resulting in poor productivity. One of the problems to solve for the industrial application is thus to maintain the arc spot on the surface of graphite target. In the present work, we investigated the effects of the cathode shape and magnetic field structure on the arc spot motion. The structures of source and extraction magnetic fields and the shape of the cathode were optimized in the view point of arc stability by both computer simulations and experimental works. The FVA source was composed of graphite cathode of diameter 80mm, anode of diameter 90mm, 60 degree bending magnetic filter and 4 solenoid magnets for extraction, bending, outlet and respectively reflection. We could obtain continuous operation of the arc source for few hours at the ion current of 300mA at the distance of 100mm from the exit of the arc source. Amorphic diamond films were deposited on Si (100) wafer for various bias voltages ranging from 0 to -250V. With increasing the bias voltage, the hardness and residual stress decreased from 65 to 45Gpa and 6.4 to 3.1GPa respectively. The content of graphitic component was increased by increasing the negative bias voltage as observed in EELS and Raman spectroscopy.
BP-11 Annealing Effects on Near Stoichiometric a-SiC:H Films
A.L. Baia Neto, S.S. Camargo Jr. (Universidade Federal do Rio de Janeiro, Brazil); F. Finger, R. Carius (ISI-PV, KFA-Juelich, Germany)
Crystalline silicon carbide is a material which presents outstanding mechanical properties, thermal stability, resistance to oxidation, and very high thermal conductivity, among other properties. In this work, near stoichiometric amorphous silicon carbide films were deposited, at ambient temperature and a self- bias of -200 V, onto the cathode of a rf glow discharge reactor using silane-methane mixtures. Infrared results showed a predominance of Si-C bonds in the structure. The Raman spectra of the as deposited samples evidenced the existence of silicon and carbon clusters. It is observed a decrease of spin densities and ESR bandwidths accompanied by an increase of the E04 gap to 2.7 eV, with annealing temperature up to 500 °C. This result is consistent with infrared measurements that showed an increase of C-H bond density. Hydrogen evolution curves exhibit a peak above 600 °C and hydrocarbon (CH3, C2H3 and C3H3) evolution present similar behavior for all samples indicating that the responsible mechanism for gas evolution from the films is not dependent on silicon concentration. For all films annealed at temperatures higher than 500 °C it was observed a decrease of Si-H and C-H bond density while the Si-C increases, indicating that Si-C bond formation is a result of bonded hydrogen release. The increase of Id/Ig ratio observed on Raman spectra of samples annealed at temperatures higher than 750 °C indicate that an increase of the graphitic clusters size also occurs at high annealing temperature.
BP-12 Optical, Mechanical and Electrical Properties of Titanium Oxide-Like Films Deposited by PECVD
N.C. Cruz (State University of Campinas, Brazil); E.C. Rangel, J. Wang (Ifgw, Unicamp, Brazil); M.A.B. Moraes (State University of Campinas, Brazil)
Amorphous titanium oxide-like (TiOx) films containing carbon and hydrogen were deposited from glow discharge plasmas of titanium (IV) isopropoxide (C3H7O)4Ti, oxygen and argon mixtures. The discharge was generated in a stainless steel vacuum chamber by two parallel plate electrodes connected to a 13.56 MHz power supply. The substrate holder, to which a DC bias voltage could be applied, was positioned outside of the region between the two electrodes, i.e., in a region of lower plasma density. The substrate bias, VB, and the proportion of O2 to (C3H7O)4Ti - the oxygen to monomer (OTM) ratio - in the gas feed have been adopted as the principal deposition parameters. Ultraviolet-visible spectroscopy was used to determine the film thickness, the optical constants (n and k) and the optical gap, EG. From Rutherford backscattering spectroscopy, the elemental composition of the films was determined, while details in their chemical structure were evaluated by x-ray photoelectron spectroscopy and infrared spectroscopy. To measure hardness and electrical resistivity of the films, microindentation and the two-point probe technique, respectively, were used. The elemental composition, the molecular and the electronic structure of the deposited material vary strongly with VB and the OTM ratio. The hydrogen content of the films decreases with increasing VB. With rising OTM ratios, the carbon content of the films decreases, and both EG and the electrical resistivity increase. A rise in the OTM ratio also increases the hardness of the films.
BP-13 Influence of Ar+ Implantation on the Properties of Plasma Polymer Films
E.C. Rangel, N.C. Cruz, L.C. Kretly (State University of Campinas, Brazil); C.M. Lepienski (Federal University of Parana, Brazil); M.A.B. Moraes (State University of Campinas, Brazil)
Modifications of the properties of organic polymers by energetic ions is a well known subject of ion beam material processing. However, fewer studies are devoted to the changes of properties of polymer films obtained from plasmas of organic compounds due to ion irradiation. This work describes the influence of the irradiation of 150 keV Ar+ ions on the structural, optical, electrical and mechanical properties of polymer films deposited in plasmas of C2H2 and helium mixtures. The ion fluence varied from 1018 to 1021 ions/m2 at a constant current of 100 µA. Structural and optical properties were analyzed using infrared and ultraviolet-visible spectroscopies, respectively. From oxygen plasma etching experiments further structural information was obtained. A two-point probe was employed to measure the electrical resistivity. Hardness measurements were made using a nanoindenter. The computational code TRIM was used to simulate the Ar+ energy-loss mechanisms to the material. Infrared spectra showed depletion of hydrogen and increased concentration of double C bonds with increasing ion fluence. As a consequence the optical, electrical and mechanical properties are also modified. The etching experiments show that chain degradation prevails at lower ion fluences; for higher fluences, chain cross-linking dominates. The optical transmission in the uv and visible regions is also diminished with the fluence, reflecting a shrinkage of the optical gap. The electrical resistivity strongly decreases with increasing ion fluence; the resistivity of the as-deposited samples decreased by ten orders of magnitude for a fluence of 1021 ions/m2. Increasing values of hardness were measured as the ion fluence was increased.
BP-14 Microstructure and Mechanical Behavior of Ion Nitrided of AISI 8620 Steel
A. Celik, I. Efeoglu, G. Sakar (Ataturk University, Turkey)
The mechanical and structural properties of plasma nitrided AISI 8620 steel were investigated. The plasma nitriding process variables included time (0.5 - 8h), temperature (450, 550, and 600 °C) and gas mixture (70% H2, 30% N2). The variation of the performed white layer has been investigated by optical, and scanning electron microscopy (SEM). Mechanical and structural changes at various temperatures were characterized using microhardness test and XRD. During the ion nitriding, the distribution of nitrogen through the diffusion layer has been examined by EDS.
BP-15 Comparison of Inductively Coupled Plasmas vs Helicon Driven Plasmas for Ionized PVD Applications
M.M.C. Allain, D.B Hayden, D.R. Juliano, D.N. Ruzic, M.J. Neumann (University of Illinois)
A dc planar magnetron with a 33-cm diameter target is coupled with a secondary plasma source to ionize the sputtered metal neutral flux to control the angular distribution of the flux arriving at the surface of the substrate. The secondary plasma source can be created by a multi-turn coil located inside the vacuum chamber or by a helicon antenna external to the sputtering chamber. Both of these methods increase the electron density, which results in significant ionization of the neutral metal flux from the sputtering target. By applying a small negative bias to the substrate, metal ions are drawn to the substrate at normal incidence. A gridded energy analyzer and a quartz crystal microbalance (QCM) are attached to a pulley system that allows the ion and neutral deposition rates to be determined along the substrate plane. A comparison of the ionization fraction of the flux incident onto the QCM as a function of position is shown.
BP-16 Microstructure and Properties of Nanocrystalline Ti-B-N and Ti-B-C Coatings
C. Mitterer, P. Losbichler, M. Beschliesser (The University of Leoben, Austria); P. Warbichler, F. Hofer (Technical University of Graz, Austria); P.N. Gibson, W. Gissler (Joint Research Centre of European Commission, Italy)
Ti-B-N and Ti-B-C films with a gradient in the chemical composition were deposited onto austenitic stainless steel sheets by means of unbalanced d.c. magnetron co-sputtering using segmented TiN/TiB2 and TiC/TiB2 targets. Film microstructure was characterized by means of electron-probe microanalysis (EPMA), transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), and X-ray diffraction (XRD). The mechanical properties of the coatings were measured using a depth-sensing nanoindenter. The composition of the films was found to lie close to the quasi-binary sections TiN - TiB2 and TiC - TiB2 within the ternary systems Ti-B-N and Ti-B-C, respectively. The grain size determined from TEM investigations ranges between 3 and 5 nm. Coatings consisted of nanocrystalline fcc TiN or TiC phases with boron atoms dissolved, and TiB2. Microstructure as well as chemical composition of the films were not influenced significantly by the deposition parameters used in this investigation. Contrary, the mechanical properties were strongly influenced varying the ion bombardment. Hardness values exceeding 50 GPa and elastic moduli close to 500 GPa were obtained.
BP-17 Surface Modification of Electron-Beam PVD TiAlBN Hard Coatings by Plasma Immersion Ion Implantation of Carbon
A.D. Wilson, A. Leyland, C.G. Rebholz, A. Matthews (University of Hull, UK)

The authors have developed an electron-beam (EB) evaporation technique for the deposition of complex-alloy hard ceramic coatings, based on modifications to the well-known Ti-N system by addition of Al and B to the evaporant source material [1,2]. The coatings exhibit hardnesses in excess of 40GPa [1] and can significantly out-perform commercial TiN coatings in drilling tests [2]; however the friction coefficient against steels is still quite high, at around 0.8 [1].

There are a wide range of phase composition possibilities within the Ti-Al-B-N system, which can include nitrides, diborides, boron-nitrides (both hexagonal and cubic) titanium-aluminide inter-metallics and TiN/TiB2'nanocomposite' phases. These offer a number of routes to adjust the hardness, friction and adhesion/toughness properties of TiAlBN coatings for applications other than machining, if the appropriate degree of process control can be achieved. Although significant amounts of h-BN can be incorporated into these coatings, this does not appear to lower the friction coefficient as much as might be expected [1]. This work therefore examines the use of Plasma-Immersion Ion-Implantation (PI3) as a means to introduce a high carbon content to the surface/near-surface of Ti-Al-B-N coatings and provide improved frictional characteristics.

The PI3modified coatings were produced by depositing a plasma-assisted EBPVD TiAlBN coating onto a series of tool-steel test coupons, then using a weakly-ionised low-voltage argon-methane plasma (supported by hot-filament electron emission), onto which high voltage pulses were superimposed, to PI3treat the coated coupons for different times over a range of voltages between 5 and 15kV. The friction and wear behaviour of the resulting carbon-implantation modified coatings was then assessed using both pin-on-disc and reciprocating-sliding wear tests. It is demonstrated that the PI3method provides a flexible technique for modifying the tribological characteristics of PVD hard coatings, which can be integrated into the coating process.

1.'Structure, mechanical and tribological properties of TiBN and TiAlN multiphase thin films produced by electron-beam evaporation'

C. Rebholz, H. Ziegele, A. Leyland & A. Matthews In press - J. Vac. Sci. Technol. A.

2.'Deposition and characterisation of TiAlBN coatings produced by direct electron-beamco-evaporation of Ti and a Ti-Al-B-N alloy from a twin crucible source'

C. Rebholz, J. Housden, N. Watson, A. Leyland, C. Charitidis, S. Logothetidis & A. Matthews In press - Thin Solid Films

BP-18 Deposition And Characterisation of Magnetron Sputtered Thin Films within the Ti-Al-B System.
C.G. Rebholz, A. Leyland (University of Hull, United Kingdom); A.A. Voevodin (Air Force Research Laboratory); J.M. Schneider (Linköping University, Sweden); A. Matthews (University of Hull, United Kingdom)
TiB2 coatings are attractive due to their high hardness, stiffness, corrosion and wear resistance. However, the elastic moduli of TiB2 coatings can be 3-4 times higher than those of the underlying substrate materials (e.g. steel), which can lead to large changes in stress distributions at a loaded contact and thus cause problems in practise with regards to coating adhesion, cracking and cohesive failure. To address such issues (normally dealt with the interposition of soft low modulus metallic interlayers), Al was added in varying amounts to a Ti-B coating system, in an attempt to reduce the elastic modulus and improve the effective coating adhesion, whilst still maintaining a relatively high coating hardness. TiAlB films were produced by simultaneous sputtering from TiAl and TiB2 onto Si (110) and AISI 316 substrate materials at a temperature of 150°C. The influence of different B/Al ratios (0.94-8.71) in coatings containing nominally 30 at.% Ti, on structure, mechanical and tribological properties was investigated. All coatings showed very dense structures and were found to be only partially crystalline. Evidence of Al3Ti, Ti and TiB2 phase-bonding was observed in XPS spectra analysis. Correlation of compositional and mechanical data showed that film hardness and elastic modulus increased with increasing B/Al ratio from 13 to 26 GPa and 185 to 240 GPa, respectively. Good adhesion was observed independent of the B/Al ratio and friction coefficient values of approximately 0.6 were recorded in reciprocating sliding wear experiments against SAE52100 and WC/6%Co balls. TiAlB coatings with B/Al ratio 3.89 showed a remarkable improved sliding wear resistance against WC/6%Co balls compared to commercially available TiN.
BP-19 Synthesis and Characterization of C-N Films by Hot Carbon Filament CVD
Y. Nakamura, N. Kitazawa, H. Kasai, Y. Watanabe (National Defense Academy, Japan)
C-N films were synthesized by hot carbon filament chemical vapor deposition method using a hot graphite filament and pure nitrogen gas on Si(100) substrates, and characterized by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The deposition method was improved by replacing a tungsten filament with a graphite one, to suppress the contamination from the filament. AES spectra showed that the C-N film synthesized using the tungsten filament was contaminated with tungsten impurity. On the contrary, there were no contamination in the films synthesized using the graphite filament. The atomic concentration of N varied from 1.4 % to 21.5 % depending on the filament temperature, the deposition pressure and the distance between filament and substrate. The C-N films were not formed when the filament temperature was below 1750 0C. Above 1800 0C, the N concentration decreased with increasing the filament temperature. Concerning the chemical state of bonding, the N(1s) core level photoelectron spectra indicated that the N atoms in the films bonded to both sp2-and sp3-hybridized carbon atoms. With increasing the filament temperature, N atoms bonded to sp3-hybridized carbon atoms decreased. These results suggest that the filament temperature influences not only the atomic concentration of N but also the chemical state of bonding. From these results, it can be concluded that the hot carbon filament CVD method is one of the promising candidates for preparing C-N films.
BP-20 Comparison of Electric and Magnetic Filters
C.F. Meyer, B. Schultrich (Fraunhofer - Institut f. Werkstoff und Strahltechnik, Germany); P. Siemroth (Fraunhofer Institute Material and Beam Technology, Germany); H.-J. Scheibe (Fraunhofer - Institut f. Werkstoff und Strahltechnik, Germany); T. Witke (Fraunhofer Institute Material and Beam Technology, Germany)
Notwithstanding the undisputed advantages of vacuum arc discharges, especially its high plasmas activation, such applications are usually excluded where the incorporation of droplets in the growing film cannot be accepted. To overcome this drawback different methods for filtering out the particle flux has been proposed. Crucial points are the often accompanying reduction of ion energy and ion flux, i.e. of deposition rate. New possibilities are opened by the combination of pulsed arc techniques with particle filters. Based on the well-known Akzenov-filter represented by a curved magnetic duct and the pulsed High Current Arc a particle filter with high transparency (up to 40% for carbon) and only low energy loss has been realized. It represents a high current metal ion source with ion currents in the range of some amperes (pulse ion currents of some hundred amperes). Its efficiency has been proved by the deposition of very smooth films of superhard amorphous carbon. The influence of the filtering conditions and the cathode material on the plasma flux is discussed. These results are compared with a new type of filtering based on the combination of laser induced pulsed arc (Laser-Arc) and an electric filter. Its effect is demonstrated by the deposition of metal and of oxide films.
BP-21 Microstructure and Properties of the HVOF Thermal Sprayed NiWCrBSi Coatings
M.H. Staia, L. Gil (Central University of Venezuela)
A fundamental understanding of the NiWCrBSi coatings microstructure with respect to processing parameters will led to considerable advancement in reliability and performance of the deposition process. In this context, plain steel carbon samples have been HVOF thermal sprayed by using commercial NiWCrBSi powder. The structure, morphology and the size distribution of the powder have been determined prior to the deposition process. The influence of the spraying distance and the feed powder rate at ( fuel/oxygen) = 1 on the microstructure and mechanical properties has been assessed. The coatings have been characterized by using X-ray diffraction, optical and scanning electron microscopy. Results regarding porosity, microhardness and adhesion are also reported.
BP-22 Structure and Phase Stability of the Chemically Deposited Au Layers on the Electrodeposited Ni and Ni-B Layers
I. Vitina, V. Rubene, M. Lubane, V. Belmane, A. Krumina, A. Knipele (Institute of Inorganic Chemistry, Riga Technical University, Latvia)
Changes of the surface structure and phase composition of the chemically deposited Au layers (thickness 0.1-0.3 µm) in the layer systems of Au/Ni-B/Cu and Au/Ni/Cu at thermal treatments were studied by means of transmission and scanning electron microscopies and X-ray diffraction. It has been determined that the chemically deposited Au layer in the system of Au/Ni-B/Cu maintains its structure and phase stability at the thermal treatments at 300 °C for 200 h and at 400 °C for 50 h in spite of crystallization of the electrodeposited amorphous Ni-B layer and formation of the borides Ni3B, Ni2B; formation of the intermetallics Cu3Au and AuxCuy does not take place. The electrodeposited amorphous Ni-B alloy contains 6.45-6.8 wt% of boron and (3.2-6) 10-2 wt% of carbon.
BP-23 Effect of Al content on Hardness and Lattice Parameter of (Ti,Al)N Films
A. Kimura, H. Hasegawa, K. Yamada, T. Suzuki (Keio University, Japan)
Titanium-aluminum targets were arc-discharged at ~500 °C under nitrogen plasma circumstance and (Ti,Al)N films were synthesized on mirror-polished cemented carbide. The hardness of (Ti,Al)N films increased with Al content of target until 60at% against Ti concentration, over which the hardness rapidly decreased. Correspondingly, the lattice parameter of (Ti,Al)N films monotonously decreased with the Al content when the amount of Al was less than 60at%. In this paper, effects of Al content on hardness and lattice parameter of (Ti,Al)N films were discussed and further, the microstructures of films were analyzed with high resolution electron microscopy.
BP-24 Plastic Flow and Related Friction and Wear Behaviour in Nanocrystalline TiN Ceramic Thin Films
K.J. Ma (Chung-Cheng Institute of Technology, Taiwan); A. Bloyce (The University of Birmingham, United Kingdom); D.G. Teer (Teer Coatings Ltd., Hartlebury Trading Estate, Worcestershire, United Kingdom)

Even though high strengths have been obtained in most ceramic coatings, it has also been shown that some ceramic coatings undergo extensive plastic deformation during indentation, scratch, and wear tests. It is essential to understand the plastic flow and related friction and wear behaviour. Reciprocating multipass wear tests have been carried out on unbalanced magnetron sputtered TiN coatings. Deformation and failure mechanisms were identified based on high resolution microstructural examination through cross-sectional fracture surfaces.

Sputtered TiN coatings exhibit columnar or nanocrystalline characteristics, the strain energy and residual stress can be easily dissipated or relaxed by the plastic flow of the coatings. If the interface adherence between coating and substrate is strong enough, the process of plastic flow, plastic extension, microflaking, and thinning will continue until the total penetration of the coatings.

A low coefficient of friction (?=0.06~0.08) was obtained when the wear is performed using diamond as the slider, even the occurrence of obvious plastic flow in the TiN coatings and substrate. In contrast, the coefficient of friction or energy loss is quite high (?=0.45~0.6) when the TiN coatings contact with WC/Co materials, even without the occurrence of obvious plastic flow. It is suggested that strong adhesion or interfacial bonds may be formed between the TiN coatings and WC/Co materials during the sliding process. The deformation loss is believed more important in relation to the wear or surface fatigue than in relation to friction.

BP-25 Investigationof Surface Hardness of the TiN Coated X210Cr12 Material Depending on Process Parameters
S. Danisman (Erciyes University, Turkey)
In this paper, X210Cr12 die steel has been coated with TiN on the experimental system constructed in according to triode sputtering, a PVD coating method. The effects of process parameters on the coating properties have been investigated. Before coating, experimental samples have been carried out hardening process and increased substrate strength. Reactive gas pressure, substrate temperature and coating time have been taken into account as process parameters and the effects of these parameters on the coating hardness and microstructure have been analyzed. In the experiments, N2 gas pressures, substrate temperatures and coating times have been taken between 2x10-3 - 4x10-3 mbar, 250 °C - 450 °C and 4-8 hours, respectively. As a result of microhardness measurement, it can be seen that the hardness increases in proportion to the substrate temperature and coating time. Nevertheless, it is also seen that the hardness rises with N2 gas pressure. Moreover, it is found that the critical N2 gas pressure was determined as 4x10-3 mbar after many experiments.
BP-26 Formation and Characterization of Expanded Austenite Produced by Ion Nitriding of AISI 316 SS
S. Parascandola, E. Richter, W. Möller (Forschungzentrum Rossendorf, Germany)
Samples of AISI 316 SS have been ion nitrided from a Kaufman ion source at temperatures ranging from 280C up to 480C under well defined constant process parameters. The formation range of expanded austenite is revealed by X-ray diffraction, Moessbauer spectroscopy and electron microscopy and correlated to the nitrogen profiles measured by nuclear reaction analysis and glow discharge optical emission spectroscopy. The samples are characterized by microhardness measurements, pin-on-disk wear tests and corrosion tests. The expanded austenite layers exhibit improved hardness and wear without compromising the corrosion resistance. Additionally, roughness measurements by atomic force microscopy are performed.
BP-27 Effect of Si Implantation on AISI 304 and 430 Stainless Steels Against High Temperature Cyclic Oxidation
F.J. Pérez, M.P. Hierro, M.J. Cristobal, F. Pedraza, E. Otero (Universidad Complutense de Madrid, Spain)
Ion implantation has been used as a surface modification technique in order to improve the oxidation resistance of different metallic materials. Silicon, implanted in low doses, have been established before with beneficial effects under isothermal conditions in different steels. The main goal of this work has been to establish under cyclic conditions, and with different implanted doses, if the silicon remains in beneficial effect, and if there is a critical dose for this effect. In order to study the last effect, different silicon implanted doses have been analyzed. Cyclic oxidation tests have been established up to 500 hours, and the coatings of the oxidized products have been characterized by SEM and EPMA profiles. Theoretical calculations have been performed to the implanted ions in order to achieve the deep profiles. A protection mechanism has been proposed according to the results obtained.
BP-28 Kinetic Sutdies of Cr and Al Deposition Using CVD-FBR on Different Metallic Substrates
F.J. Pérez, M.P. Hierro (Universidad Complutense de Madrid, Spain); C. Gómez (Consultant); F. Pedraza, M.C. Carpintero, E. Otero (Universidad Complutense de Madrid, Spain)
Kinetic studies of Cr and Al deposition have been established in order to optimize the diffusion coatings achieved from this method. The advantages of the CVD-FBR in deposition time and temperature of deposition allows to establish possible industrial applications. The different kinetic parameters have been obtained with and without chemical reaction in the system, using different metallic substrates, such as austenitic steels and Ni-base superalloys. According to the results obtained, the modeling of the systems have been performed.
BP-29 Effect of Si Implantationon Different Stainless Steels Against Localized Aqueous Corrosion
F.J. Pérez, M.P. Hierro, C. Gómez, F. Pedraza, L. Martinez (Universidad Complutense de Madrid, Spain)
Ion implantation has been used as a surface modification technique in order to improve the corrosion resistance of different steels. Theoretical calculations have been performed to the implanted ions in order to achieve the deep profiles. The main goals of this work will be to establish the effect of Si implanted in two stainless steels with same Cr content and with different microstructures (austenitic and ferritic) against localized aqueous corrosion. The corrosion tests will be performed using electrochemical impedance spectroscopy (EIS) in order to identify the corrosion mechanism. The surface will be characterized by AES before and after corrosion test, SEM, DRX and EPMA after corrosion tests. Corrosion mechanisms have been proposed according to the results obtained.
BP-30 Extension of Multichannel Spectroscopic Ellipsometry into the UV from 1.5 to 6.5 eV for Real Time Characterization of Hard, Wide Bandgap Thin Films
R. Messier, J.A. Zapein, R.W. Collins (Penn State University)
Real time spectroscopic ellipsometry (RTSE) extended well into the ultraviolet has been developed as a sensitive new tool for in-situ studies of wide band gap materials and thin films. For such materials and films lack of significant absorption in the visible/near-uv region limits the full capabilities of conventional visible/near-uv RTSE measurements demonstrated on lower band gap films such as Si. Hard thin films like diamond and cubic boron nitride are wide bandgap materials (5.5eV and 6.3eV respectively) suitable to being studied with this new instrumentation. This is particularly true for mixed phase wide band gap films in which the lack of absorption for both phases severely limit the sensitivity of the data analysis. These conditions prevail for the boron nitride system in which case the high-energy gaps of the cubic (6.1 - 6.6 eV) and hexagonal (4.1 eV) phases are not well resolved by visible/near-uv spectroscopic ellipsometry alone, and the possible presence of voids in the films further limit optical analysis capabilities. We report here the development of a rotating polarizer multichannel ellipsometer operating in the region from 1.5 to 6.5eV and its application for the first time to in-situ, real time characterization of hard, wide bandgap materials over this broad spectral range. R.C. DeVries, in "Diamond and Diamond-like Films and Coatings", edited by R. E. Clausing et al., Plenum Press, New York, 1991. O. Stenzel et al., Phys. Stat. Sol. (a) 158, 281 (1996).
BP-31 Stress Relief of Tetrahedral Amorphous Carbon Films Grown By Filtered Cathodic Vacuum Arc Technique
B.K. Tay, X. Shi, E. Liu, J.R. Shi, L.K. Cheah (Nanyang Technological University, Singapore)

Over the past few years, tetrahedral amorphous carbon (ta-C) films grown by Filtered Cathodic Vacuum Arc (FCVA) technique have attracted considerable interests owning to their unique combination of properties. Among the important properties of these films are high hardness, low coefficient of friction and optical transparency. The unusual combination of these properties has stimulated studies on various applications such as optical coatings, high endurance and low friction coatings. However, it is well known that typical films with diamondlike properties have very high residual compressive stresses after growth (12~14 GPa), which result in the delamination of thick films from their substrates. Therefore the large compressive stress has been one of the obstacles to the application of ta-C coatings. In this paper, the stress relief of ta-C films by post deposition thermal annealing is investigated.

The details of the FCVA deposition system have been published elsewhere. The system incorporates the off-plane double-bend (OPDB) filter to effectively remove all macro-particles. Tetrahedral amorphous carbon films were deposited at 100 eV ion energy (maximum sp3content) with the substrate held at room temperature. The film thickness was typically 70 nm. Two sets of experiments to anneal the films in low vacuum with argon (~10-2 torr) at different temperatures ranging from 500 to 800 degree C were carried out. The samples in the two sets were kept at each annealing temperature for 2 minutes (Set A) and 30 minutes (Set B) respectively and allowed to cool down back to room temperature for other measurements. A Tencor P-10 surface profilometer was used to determine the stress of each film in all the sets. By using the Radius of Curvature Technique, the relative change in stress before and after heat treatment for each film was computed. To obtain qualitative information about the changes in the structure of the carbon films, Raman spectra were measured at room temperature on a Renishaw system using the 514.5 nm lines of Ar+ laser as excitation source. Typically, the spectra were acquired in the backscattering geometry over the range of 400 cm-1 to 4000 cm-1. Low input power was used in order to avoid annealing effects under laser irradiation.

The relative change in compressive stress as a function of heat treatment temperature for films subjected to different annealing time is plotted. In general, for all the films, the stress decreases (by 60% to 95%) with increasing heat treatment temperature. However for the same heat treatment temperature, the stress decreases much more prominently for films subjected to 2 minutes annealing time. A ta-C film subjected to 600 degree C heat treatment for 2 minutes annealing time has a stress reduction of 85% as compared to 70% for 30 minutes annealing time.

The Raman spectra of the ta-C films generally exhibit a broad intensity distribution at around 1560 cm-1, which is characteristic of hydrogen-free amorphous diamond-like carbon films. In order to analyze the spectra quantitatively, the Raman spectra were fit to the two Gaussian peaks using PeakFit, a least-squares computer program. It can be seen for increasing temperature, the D peak becomes more noticeable and the G peak shifts toward 1585 cm-1, which is also the wavenumber for the main peak of crystalline graphite. It is interesting to note that the integrated intensity ratio (ID/IG) obtained from the fitting results registered a smaller increase for films subjected to 2 minutes annealing. The ID/IG ratio for the ta-C film subjected to 600 degree C heat treatment for the 2 minutes annealing time is 0.35 as compared to 0.5 for the 30 minutes annealing time. The intensity ratio result correlates very well with the G peak position and its linewidth. An upward frequency shift of the G band and the narrowing of the G band with increasing heat treatment temperature were also observed. These changes in the Raman spectrum suggest graphitization of the films. It has been reported that the position of the G-band and its linewidth in the Raman spectrum for amorphous carbon films are correlated to at least two film properties - the sp3/sp2 ratio and the film stress where a lower sp3 content and /or lower stress leads to a lower G linewidth. The relatively smaller change in the intensity ratio and the larger reduction in G linewidth observed for the 2 minutes annealed ta-C films suggests that higher stress relief of ta-C films can best be achieved by a shorter thermal annealing without sacrificing much degradation in its diamond-like properties.

In view of the high stress relief in the annealed films, subsequent deposition and annealing steps can be carried out to deposit thicker films. Initial results show that several layers can be deposited and yet high diamond-like quality films can be obtained.

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