Papers

ICMCTF2002 Session BP-1: Symposium B Poster Session

Tuesday, April 23, 2002 5:00 PM in Room Town & Country

Tuesday Afternoon

Time Period TuP Sessions | Topic B Sessions | Time Periods | Topics | ICMCTF2002 Schedule

BP-1-1 Bohm Diffusion in Plasma Transport Through a Magnetic Filter T. Zhang, P.K. Chu (City University of Hong Kong); H.X. Zhang (Bejing Normal University, China); I.G. Brown (Lawrence Berkeley National Laboratory) Cathodic arc plasma is of increasing importance in thin film deposition, metal ion implantation, as well as plasma immersion ion implantation (PIII). The favorable characteristics of a cathodic arc plasma source are the high ion flux and high degree of ionization of the metal plasma. However, cathodic arc plasmas suffer from macro-particle contamination. The most common method to remove macro-particles is to insert a curved magnetic filter between the source and samples. The two most important parameters in designing magnetic filters are the bias voltage and magnetic field. The magnetic field limits the electron motion in the radial direction and the positive bias prevents ions from colliding with the filter wall. Both these factors also prevent plasma diffusion along the radial direction of the filter into the filter wall. The relationship between the bias and plasma transport with magnetic field has been investigated. Our experimental results on the plasma transport through the filter show the characteristics of Bohm diffusion. An improved model based on Bohm diffusion is used to investigate the optimal bias of the filter. Details regarding the derivation of the model as well as experimental results will be presented in this paper.
BP-1-2 The Deposition of NbN and NbC Thin Films by Filtered Arc Process A. Bendavid, P.J. Martin, T.J. Kinder, E Preston (CSIRO, Australia) Thin films of niobium nitride, niobium carbide has been deposited on conducting (100) silicon wafers by filtered arc deposition (FAD). The influences of the depositing Nb+ energy, nitrogen and methane pressure on the structure, composition and mechanical properties have been investigated. The results of X-ray diffraction showed that with increasing substrate bias there is an increase in the preferred orientation. Composition results showed that both NbN and NbC films were stoichiometric with no detectable change with increase in the substrate bias at working pressure used. Hardness and stress measurements also confirmed the increase in the preferred orientation. The hardness range of NbN and NbC films were found to be between 25-46 GPa and the compressive stress was found to vary over 3-8.5 GPa.
BP-1-3 Impact Testing of Duplex and Non-Duplex (Ti,Al)N and Cr-N PVD Coatings J.C.A. Batista, C. Godoy (Universidade Federal de Minas Gerais, Brazil); A. Matthews (University of Hull, United Kingdom) An impact test has been used to evaluate the impact resistance of duplex (i.e. pre-nitrided) and non-duplex PVD (Ti,Al)N and Cr-N coatings. The impact tests were carried out using a cyclic loading system developed at the University of Hull. Two different balls (tungsten carbide and hardened AISI E52100 steel) were used as impact bodies. After the test, samples were observed on the scanning electron microscope in order to investigate coating failure. Experimental results revealed that both duplex (Ti,Al)N and Cr-N coatings displayed better impact resistance than their non-duplex counterparts. None of the duplex coatings exhibited adhesive failures up to 5x10⁴ impacts when both tungsten carbide and hardened steel balls were used. Conversely, all non-duplex coatings displayed adhesive failures at lower numbers of impact cycles. The nitrided case minimised substrate deformation under the hard PVD coatings so that fewer cohesive failures occurred in the duplex coatings. Moreover, the improvements of the duplex treatment could be more markedly noted when tungsten carbide balls were used, since higher stresses are expected to occur for this impact body. A mechanism involving material transfer from the ball to the coated surface was observed to occur only for the duplex (Ti,Al)N coating. A larger amount of transferred material took place for tests carried out with hardened steel balls, probably owing to their relatively lower hardness in comparison to that of the tungsten carbide balls. Such a mechanism was not observed to occur for the duplex Cr-N coating, which seemed to be the most suitable coating among all those tested, to be used in dynamic loading wear applications.
BP-1-4 Atmospheric Pressure Deposition of SiC Using Resonant Structure Microwave Plasma CVD System. J.M. Hong, S.Y. Kim, K. Hoon Lee, K. Ho Lee (Institute for Advanced Engineering, Korea) SiC film has been deposited on Si (100) substrate using two different systems of TE011/TE411 modes coupled cavity and non-resonant waveguide type applicator with 1-2kW microwave plasma source at atmospheric pressure (760torr). Stable plasma discharge of source gases(Ar/HMDS) was sustained with tangential guiding flow of nitrogen gas. The different performances between the resonant structure and the non-resonant structure for the growth of SiC film have been investigated with optical emission diagnostics. According to the pLSE(partial Local Saha Equilibrium) model, electron temperature, electron density and the gas temperature were measured for the analysis of discharge characteristics. The physical properties of SiC film have been observed to have a strong relationship with plasma parameters as expected. In addition, microwave resonant cavity has revealed the possibility of the large area deposition and high growth rate. In conclusion, the resonant structure microwave source is expected to suggest a very effective high density plasma CVD process compared with conventional system.
BP-1-5 Preparation of Hydroxyapatite Layer by Ion Beam Assisted Simultaneous Vapor Deposition M. Hamdi, A.M. Ektessabi (Kyoto University, Japan) Hydroxyapatite (HAp) layer was prepared by using the technique of ion beam assisted simultaneous vapor deposition (IBASVD). The method comprised of an electron beam and a resistance heater vaporizing CaO and P₂O₅, respectively, while an Ar ion beam was focused on the substrate to assist the deposition. All deposited layers were amorphous, regardless of the current density level of the ion beam. Post heat treatment was applied to crystallize the deposited coatings. XRD reveals that samples with ion beam current density of 180 µA/cm2 show more HAp peaks then the ones with 260 µA/cm2. The Ca/P ratio increased with increasing ion beam current density presumably due to the high sputtering rate of P compared to that of Ca from the layer being coated. Annealing the samples increased the ratio even further due to the dissolution of P at high temperature. Improvement in the bond strength between the layer and the substrate was observed.
BP-1-6 New Generation of Periodontal Instruments with Filtered Arc Coatings V. Gorokhovsky (Arcomac Plasma Processing Laboratory, Canada); N. Bekesch (Arcomac Plasma Processing Lab, Canada); P. Watson (University of Toronto, Canada); A. Deckmar, D. Meuchel, J. Smithers (American Eagle Instruments, Inc.); E. Bergmann (Ecole d'Ingenieurs de Geneva, Switzerland) A dual-filtered cathodic arc deposition process was used to deposit a multi-layer cermet coatings on periodontal dental instruments made of martensitic stainless steel, using industrial Large Area Filtered Arc Deposition (LAFAD) surface engineering system ¹. A custom mechanical stroking device was developed to include features capable of simulating the load and motion of dental scalers against enamel or dentin tooth surfaces in an aqueous environment. The working edge wear was than investigated by means of optical and electron spectroscopy as well as metallurgical cross-section profile. Corrosion resistance of dental instruments with multi-layer coatings was studied by subjecting of the instruments to conventional sterilization procedure. Comparison of the laboratory tests with the field testing results in dental clinical practice is presented. @@super1@ Vladimir I. Gorokhovsky , Rabi Bhattacharya and Deepak G. Bhat, Surface and Coating Technology, 140 (2) 2001, pp. 82-92.
BP-1-7 Pulsed Plasma Nitriding and Post -Oxidation of Steel Samples M. Zlatanovic (Faculty of Electrical Engineering, Yugoslavia); N. Popovic, Z. Bogdanov (The Vinca, Institute of Nuclear Sciences, Yugoslavia); S. Zlatanovic (University San Diego) Plasma nitrided samples made of steel grade DIN Ck 45 and 42 CrMo 4 were post oxidized in a mixtures of H2 and O2 gases using pulse power supply. Plasma nitrocarburizing was performed at 5200C, and oxidation at 5000C, total processing time being 15 hours The applied JONOXïƒ’ process is a combination of plasma nitriding or plasma nitrocarburizing and plasma oxidation of the compound zone. Pulse plasma was used in all process steps at 5kHz and pause/pulse ratio 1:9. The XRD examination revealed the existence of the compound zone composed of Fe4N with a magnetite Fe3O4 thin overlayer. The architecture of formed surface structure provides the unique mechanical and tribological properties with the diffusion zone responsible for load bearing capacity, wear and fatigue resistance and the double compound layer resistant to wear and corrosion. The results of Vickers microhardness measurements, XRD and SEM analysis, optical microscopy examination and corrosion tests were presented.
BP-1-8 DLC Thin Film Preparation by Cathodic Arc Deposition with a Super Droplet-free System H. Takikawa, K. Izumi, T. Sakakibara (Toyohashi University of Technology, Japan) Diamond-like carbon (DLC) films are fabricated by means of cathodic vacuum arc with graphite cathode and investigated from a viewpoint of the number of macrodroplets on the film, observed with an optical microscope. When a negative bias was applied to the substrate, the number of macrodroplets decreased by approximately two-third at a constant deposition time. However, the deposition rate also decreased, when the negative bias was applied. The magnetic transportation of the plasma was able to improve the deposition rate. DLC film was also prepared by the magnetically transported cathodic arc with a super droplet-free system, which was a newly developed cathodic arc deposition system. The macrodroplets on the film prepared by this system was successfully reduced.
BP-1-9 Finite Element Modeling of the Indentation into Superhard Coatings J.L. He (Institute for Chemistry of Inorganic Materials, Technical University Munich, Lichtenbergstr. 4, D-85747 Garching, Germany); S. Veprek (Technical University Munich, Germany) Load-depth sensing technique is now widely used to measure the hardness and elastic modulus of coatings. However, when the hardness of the coating is much higher than that of the substrate, the load-depth sensing technique is subjected to a larger influence from the substrate than the classical measurement of Vickers hardness from the projected area of the remaining plastic deformation. We applied finite element modeling to examine the elastic and plastic response of both the superhard coatings and the softer substrates. It was found that for a superhard film on a soft substrate, the influence from substrate is evident even when the maximum indentation depth is less than 1/10 of the film thickness. The loading procedure causes a larger maximum indentation depth which results in underestimate of the film hardness. The unloading procedure gives a smaller contact stiffness resulting in an underestimate of the elastic modulus. The presence of soft substrates also influences the distribution of the stress under the indenter. The stress near the interface is intensified by the soft substrate. Plastic deformation of a soft substrate is observed even when the indentation depth is less than 1/10 of the film thickness. All these results indicated that, for superhard films (≥40Gpa), reliable measurements can be done only on ≥10µm thick coatings in order to avoid substrate influence and errors due to indentation size effect (indenter tip blunting etc.).
BP-1-10 Growth and Characterization of Thin Films of Thermoelectric BiSb Alloy R.C. Mallik, V. Damadara Das, S. Kasiviswanathan (Indian Institute of Technology Madras, India) The alloy of Bismuth and Antimony was prepared by the melt-quenching technique. Thin films of Bi0.92Sb0.08 alloy of different thicknesses were prepared by the flash evaporation technique. The thickness was measured in-situ by the quartz crystal thickness monitor. The electrical resistivity and thermoelectric power of the as-grown thin films were measured in the temperature range of 120 K to 300 K. The thermoelectric power and electrical resistivity vary with both temperature and thickness. It was found that the thermoelectric power was negative and remained constant with a value of about -180 (V/K from 120 K to 210 K and increased rapidly to -1000 (V/K as temperature increased to 220 K. The results obtained were compared with the previously reported data and discussed. In this paper we also give details about the automated arrangement for the measurement of thermoelectric power and electrical resistivity of the thin films.
BP-1-11 Characteristics of Martensitic Stainless Steel Nitrided in a Low-pressure rf Plasma S.K. Kim, J.S. Yoo (University of Ulsan, Korea); J.M. Priest, M.P. Fewell (University of New England, Australia) Martensitic grade of stainless steel AISI 420 was nitrided in a low-pressure rf plasma using pure nitrogen. A treatment time of 4.0h at 400 °C, the nitrogen rich layer on AISI 420 is 20 micron thick and has a hardness about 4.3 times higher than that of the untreated material. The layer thickness is much greater than that obtained on AISI 304 under identical treatment conditions, reflecting the different Cr content of the two alloys. Below the temperature at which CrN forms, the treated layer retains its martensitic structures, but with a large lattice parameter than the bulk, a phase that can be termed 'expanded martensite', by analogy with the situation with austenitic stainless steel. Kinetics of the layer formation was investigated. An activation energy of 33.4 kJ/mol was obtained.
BP-1-12 Corrosion Resistance of Chromium Carbide on 304 Stainless Steel by Cathodic Arc Deposition K.-L. Chang (National Tsing Hua University, Taiwan, ROC); S. Han (National Taichung Institute Technology, Taiwan, R.O.C.); J.H. Lin, H.C. Shih (National Tsing Hua University, Taiwan, ROC) Stainless steel is commonly used as a container material in chemical industries. Hard coating plays a role of protecting substrate in corrosive environments. The electrochemical behavior of deposited chromium carbide coatings on 304 stainless steel has been investigated in this study. The chromium carbide coatings were prepared by using a reactive cathodic arc plasma deposition technology. The composition and structure of Cr_xC_y were studied by x-ray diffraction (XRD),x-ray photoelectron spectroscopy (XPS) , and Raman spectroscopy. The corrosion resistance of samples was investigated by EIS and potentidynamic measurements in a mixture of acid and saline solutions. The corroded samples were also examined by scanning electron microscopy to perform a microstructural analysis. Ion chromatography (IC) was used to identify the chemical state of the dissolved species after electrochemical corrosion tests. The microstructural features and corrosion performance were then compared. It was observed that stainless steel with Cr_xC_y coating had less corrosion than that without coating.
BP-1-13 Effect of Plasma Duct Bias Voltage on Plasma Characteristics of Filtered Vacuum Arc Source J.-K. Kim, E Byon, S. Lee (Korea Institute of Machinery & Materials, Korea); K.H. Kim (Pusan National University, Korea); G.-H. Lee (Korea Institute of Machinery & Materials, Korea) Filtered vacuum arc source (FVAS) with the plasma duct that was electrically isolated from the ground has been set up. Plasma duct was enveloped by the magnetic filter and had a role in leading the plasma from the cathode to the substrate as well as to prevent the macro-particles reaching the substrate. It is believed that the potential of the plasma duct can change the transport properties of the magnetic filter because it creates a potential sheath at the duct wall and affect transportation of the ion and electron from the plasma to the duct wall.Different kinds of the plasma duct bias voltage (biased positive, floating, ground and negative voltage, respectively) and the currents of filter magnet were applied to the plasma duct. The arc discharge voltage, plasma duct current and ion beam current were measured. The variations of electron temperature and plasma density at near the substrate were examined using the electric probe.From the experimental results, with increasing positively plasma duct bias voltage, the arc discharge voltage was decreased, which resulted in stabilizing the arc spot motion, and the ion beam current and the deposition rate were increased. It was also shown that the electron temperature and plasma density were high value when the bias voltage of the plasma duct was floated and the currents of filter magnet were increased. At the positive voltage of the plasma duct bias, the arc discharge voltage, plasma duct potential and ion beam current densities were -23 V ~ -29 V, +40 V ~ +45 V and 2.7 mA/cm² ~ 3.8 mA/cm², respectively.
BP-1-15 Effects of Carbon Incorporation in Tungsten Carbide Films Deposited by r.f Magnetron Sputtering: Single Layers and Multilayers C. Rincón (Universidad Autónoma de Occidente, Colombia); J. Romero, E. Martínez, J. Esteve, A. Lousa (Universitat de Barcelona, Catalunya, Spain) Tungsten carbide coatings with different carbon content have been obtained by r.f. magnetron sputtering from a sintered pure WC target on high-speed steel. A chromium buffer layer was deposited to enhance coatings adhesion. Two different sputtering deposition processes were proved in order to deposit tungsten carbides with two stoichiometries: one with pure Ar, and the other with a reactive Ar/CH₄ mixture. Single tungsten carbide coatings obtained with pure Ar show a cubic WC_1-x phase with a strong (200) crystallographic orientation, while single coatings deposited in the reactive mixture of gases show a (111) preferred orientation. Multilayer structures were also deposited by sequentially changing the sputtering gas composition between both single layer deposition conditions. The bilayer period was thus varied from 90 to 10 nm. SIMS analysis confirmed the coatings multilayer structure. XRD analysis of the multilayers shows a combination of the orientations obtained for single layers with a progressive decrease of (200) orientation when decreasing the bilayer period. Nanoindentation and ball-on-disk tests were performed over all the coatings to compare their mechanical and tribological properties.
BP-1-16 Nanometric Chromium/Chromium Carbide Multilayers for Tribological Applications J. Romero, A. Lousa, E. Martínez, J. Esteve (Universitat de Barcelona, Catalunya, Spain) Metal/Ceramic multilayers with periods in the nanometric range as protective coatings have been studied during the past years due to their tribological and mechanical improvement respect to single coatings. We have evaluated nanometric Chromium/Chromium Carbide multilayers as a promising combination for tribological applications. These multilayers were synthesized by r.f. magnetron sputtering from a pure chromium target onto different substrates: silicon, steel and sintered tungsten carbide. The multilayer structure was obtained by alternatively changing the sputtering gas composition between pure argon and a reactive mixture Ar/CH₄. The total thickness was about 1 mm, and the bilayer period varied from 100 to 10 nm. Secondary ions mass spectrometry (SIMS) and electron microscopy confirmed the periodic multilayered structure. X-ray diffraction (XRD) allowed the characterization of the different phases formed in the Chromium-Chromium Carbide system. The influence of deposition parameters and period thickness on coatings microstructure and mechanical properties is presented.
BP-1-17 Surface Modification of Aluminum by Dielectric Barrier Discharges under Atmospheric Pressure J.F. Behnke, H. Steffen, A. Sonnenfeld (University of Greifswald, Germany); R. Foest (Institute for Low Temperature Plasma Physics Greifswald, Germany); R. Hippler (University of Greifswald, Germany) The dielectric barrier discharge (DBD) under atmospheric pressure is promising for surface modification of metallic substrates. The application of the DBD for the cleaning of hydrocarbon contaminated surfaces, for the modification of metallic surfaces by oxidation, and for deposition of silicon organic films will be reported. The DBD was used in the filamentary mode at a frequency of 10 kHz. A dielectric electrode (Al₂O₃) with an area of 80 x 20 mm² was positioned above the substrate (plain aluminum sheets, 80 x 150 mm²). The arrangement allowed the motion of the substrate relatively to the electrode at a fixed discharge gap of 1 mm. Applied voltage and electrical power input to the plasma were measured. Typical values varied between 2 - 6 kV and 50 - 150 W, respectively. The surface cleaning and oxidation experiments were carried out in dry air at atmospheric pressure. For the deposition experiments 0.1% tetraethoxysilane (TEOS) was added to the carrier gas nitrogen. It will be demonstrated, that hydrocarbon-containing films up to a thickness of 100 nm were removed within about 10 s. The cleaning process was succeeded by the growth of a compact Al₂O₃ coating (15 nm). The oxidation rate decreased exponential with a time constant of about 3 min. The results were verified by gravimetric and ellipsometric investigations, and angle resolved XPS analysis. The deposited silicon organic films are mostly solid and brittle. Their protective properties will be discussed in relation to the growth rate and the chemical structure of the deposit derived from FTIR absorption measurements. This work was financially supported by the BMBF, grant 13N7351/0.
BP-1-18 Synthesis of Multilayer Metal-ceramic Coatings by Discrete Vacuum-plasma Condensation Method with Ion Bombardment A.A. Romanov (Kharkov National University, Ukraine); V.A. Zavaleyev (Scientific Physical and Technical Center, Ukraine); A.N. Styervoyedov (Kharkov National University, Ukraine) One of the most widespread and, at the same time, promising PVD technologies is the vacuum-plasma condensation with ion bombardment, that continues to be investigated and intensively introduced into industry. The plants and production technologies of multilayer, metal-ceramic, antiwear, stable, protective and decorative coatings by discrete vacuum-plasma condensation method with ion bombardment and pulse-width parameter control of the technological process designed by us are the development of this direction. The developed plants and units to them, for example, new, simple in a design and in service, electroarc evaporators, possess lowered energy consumption, small sluggishness and increased reliability. Novel algorithms and program-technical control means of the facilities and technological process accelerate new mode adjustment of coatings deposition, completely eliminate the operator mistakes, allow to achieve 100 % results repeatability, to realize unique technological operations, and also to create banks of modes and multilayer synthesis technologies of metal-ceramic coatings on the model, instrumental and constructional materials and products.
BP-1-19 Synthesis of a Gradient Metal-ceramic Coatings and Thin Films. The Equipment and Researches A.G. Guglya, I.M. Neklyudov (National Science Center "Kharkov Institute of Physics and Technology", Ukraine); M.Yu. Silkin, N.G. Styervoyedov (Kharkov National University, Ukraine) Combined using of PVD, the ion implantation and electron material surface treatment that in a combination allow creating unique surface structures and alloys represents practical and scientific interest. It is possible to form a metal-ceramic and gradient coatings with a various composition, physical and chemical properties, concentration and dimensional performances, improved technological quality of products especially in critical conditions of high dynamic, corrosion, erosive and thermal duty by means of varying density of evaporated metal streams, pulsed electron beam power, current and energy of ions and change of its kind. In this paper, the study results of the surface layers and thin films obtained by combination IBAD and pulsed electron treatment are presented. The Computer-based control system and experimental vacuum-technological plant and also the beam plasma-emission systems designed for electronic evaporators, electron guns and the ion injectors are described. The basic technological process uses such deposition materials as Ti, Zr, Cr, AL, Ni, Mo, W, Nb, C, Si, Au, Pd, Pt, Ag, Cu and other materials, N⁺, O⁺, Ar⁺ ion beams in the range of energy from 20 up to 100 keV and pulsed electron beam with energy up to 50 keV.
BP-1-20 Ablation of Molybdenum, Niobium and Tungsten using a HyBrlD Copper Laser. M.A. Priante (Institute of Advanced Studies, Brazil); R. Riva (Institute of Advanced Studies, Brzail); N.A.S. Rodrigues (Institute of Advanced Studies, Brazil); C.A.B. Silveira (Institute of Advanced Institute, Brazil); C. Schwab (Institute of Advanced Studies, Brazil) A HyBrID copper laser with 12 W of maximum average power, 16 kHz repetition rate and 35 ns pulse duration, emitting simultaneously in 512 and 578 nm, was used to study tungsten, niobium and molybdenum ablation for film deposition purposes. A modified Balzer QMG-311 mass spectrometer was used to monitor presence of metal vapor, a pair of polarized flat electrodes placed parallel to the metal vapor stream was used to observe electric charges formation and thin films deposition on BK7 optical-quality flats allowed the estimation of film deposition rate. The ablation thresholds, obtained by measuring with the mass spectrometer, of 6.5 J/cm², 5.7 J/cm² and 7.4 J/cm² for Mo, Nb and W, respectively, agreed well with theoretical estimations. Charge formation was observed for laser fluencies bellow the vapor formation thresholds and this was attributed to thermoionic emission. The maximum film growth rate in our experimental facility was measured to be about 16 Angstrons/min for Mo and 11 Agnstrons/min for Nb.
BP-1-21 Characterization of a Reactive Arc Plasma J.M. Schneider (RWTH-Aachen, Germany); J. Rosen (Linkoping University, Sweden); A. Anders (LBNL, Berkeley) The plasma composition, average charge state values, as well as the kinetic energy of the aluminum ions have been measured by TOF spectrometry as a function of the oxygen partial pressure. The plasma was produced in cathodic arc spots. It was found that the oxygen partial pressure reduces the average charge state as well as the kinetic ion energy. These data are important for the evolution of both composition and structure during thin film growth from highly ionized plasma.
BP-1-23 Characterization of PVD Interlayers Used to Grow CVD Diamond Coatings V. Teixeira, F. Vaz, A. Monteiro (Universidade do Minho, Portugal); F. Silva (Instituto Politecnico do Porto, Portugal); Q. Fan (Applied Films); M. Baptista (Universidade do Porto, Portugal); E. Pereira (Universidade de Aveiro, Portugal) The use of interlayers such as Ti, Cu , Si, as well composite and graded interlayers to grow well adherent and polycrystalline diamond coatings by CVD is of extreme importance to deposit such hard coatings on conventional metallic components such as steel used as cutting tools in conditions of high wear and abrasion. In this contribution we present a study of PVD interlayers which are being developing to grow well adherent CVD diamong coating in cutting tool steels. The function of such interlayers should be threefold: i) to create a diffusion barrier for carbon and such substrate as metals cobalt and iron; ii) stress reduction to improve adherence by reduction of the mismatch between the coefficients of thermal expansion (CTE) of diamond and substrate material; iii) to garantee a high diamond nucleation density to obtain high quality nanocrystalline diamond coatings. Residual stresses are observed in coatings grown by PVD and CVD techniques. Residual stress is a key property for the present technological application. Firstly, residual stress may cause fracture of the coating and influence other coating properties like the corrosion and wear resistance. Secondly, the residual coating stress, together with chemical bonding, determines the coatingâ€™s adherence. Stress components are thermal stress due to a CTE mismatch between substrate and coating and a stress component which is intrinsic to the deposition technique. In this paper both the nucleation of diamond and cracking generation due to the residual stress distribution in the layered coating systems are also analysed. A stress model is outlined and it is expected to contribute to a better understanding of failure modes during diamond coating deposition.
BP-1-24 Characterisation and Tribological Evaluation of Magnetron Sputtered Nitrogen-Containing Molybdenum Copper Based Nanocomposite Films. M.C Joseph, C. Tsotsos, A. Leyland, A. Matthews (University of Hull, United Kingdom) There is increasing interest in the development of super hard coatings, which also have a high elastic modulus. These have been produced by the manipulation of nanostructured coatings based on ceramic/ceramic and ceramic/metal phased compositions. This paper reports on the structural, mechanical and tribological properties of predominantly metallic molybdenum-copper films doped with small amounts of nitrogen to produce films, which contain either no nitride phase or small amounts of lower nitrides (i.e. Mo₂N). All films were deposited on Si wafer, M2 and 316 stainless steel by reactive sputtering using a filament-enhanced dc unbalanced magnetron system. A systematic approach was adopted to investigate the properties of metal/metal and ceramic/metal phase combinations produced with increasing nitrogen content. Chemical composition and microstructure was determined by GDOES, TEM, XPS and SEM. XRD was used to identify metal nitride phases. Mechanical properties such as hardness and elastic modulus were determined by nanoindentation and Knoop microhardness. Reciprocating sliding, microabrasion and high frequency impact wear testing were performed to assess tribological performance.
BP-1-25 Optical Properties of ZnO Thin Films Deposited by rf Magnetron Sputtering for Window Application. F.S. Mahmood (Government College Multan, Pakistan); R.D. Gould (Keele University, United Kingdom) The fundamental optical parameters of ZnO thin films deposited by r magnetron sputtering in ambient of Ar are reported. The optical measurement were made in wavelength range 30-800nm. The optical spectra of the thin films of thickness 80 - 2000 nm were found to be transparent in the visible region above 400 nm wavelength having transmission (76% - 94%). The transmittance increased for films deposited at higher pressure. Absoeption edge shifted towards the large wavelength as the deposition rate increased. The optical band gap of the ZnO films was estimated by extrapolation. The valuesof direct band gap E_g are of the order of ( 3.146 - 3.28) eV for film deposited at deposition rate of the order of ( 0,163 - 0.422) nms^-1. Refractive index n (1.85 - 2.14) was computed using the interference fringes of thin films. The extinction coefficient K decreases sharply to reach a minimum range value and then saturated with increase in wavelength of the incident photons in the visible range.
BP-1-26 High-temperature Oxidation Property of CrN/AlN Superlattice Coatings G.S. Kim, S.Y. Lee, B.S. Kim (Hankuk Aviation University, Korea) CrN/AlN multiplayer films with superlattice characteristics were deposited on AISI H13 steel and Si wafer by reactive unbalanced magnetron sputtering. The coatings were synthesized with various modulation periods which were controlled by changing time above the Cr and Al targets alternatively with rotation monitor, and total coating thickness was 3~4µm. Coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), cross-section TEM and glow discharge optical emission spectroscopy (GDOES). Scratch tests, hardness, impact wear tests and high temperature oxidation resistance measurements of the coatings have also been performed. The hardness of coatings was measured to be approximately 35~40Gpa. Oxidation behavior involving thermogravimetic analysis (TGA), XRD and SEM revealed that all coatings exhibited good oxidation resistance and the resistance to oxidation was found to be dependent on modulation periods of coating. Detailed results will be presented.
BP-1-27 Structural and Discharging Properties of MgO Thin Films Prepared by Ion Beam-Assisted Evaporation Z.N. Yu (Itswell Co., Ltd., Korea); J.-W. Seo (Hongik University, Korea); D.X. Zheng, J. . Sun (Jiaotong University, China) As a protective layer for AC-plasma display panel (AC-PDP), MgO thin film can not only protect the electrodes from erosion and prolong the device lifetime, but also lower the sustaining voltage and increase the light intensity. In order to improve lifetime and lower sustaining voltage, it is necessary to enhance both densification and electron emission coefficient of the protective layer. And MgO thin films prepared by ion beam-assisted deposition have been investigated. The deposited films exhibit mainly (200) and (111) preferable orientation. Assisting ion energy and species as well as substrate temperature effect the structure of MgO thin films. From the cross-sectional feature, the density and the refractive index, it could be shown that MgO thin films prepared by ion beam-assisted deposition are dense and closely adhesive to substrate. MgO thin films deposited by argon ion-assisted evaporation produce low sustaining voltage, and longer lifetime of PDP than ones done by electron beam evaporation.
BP-1-28 Influence of Geometry and Kinematics on the Deposition of ta-C in Industrial Vacuum Arc Coaters B. Schultrich, S. Voellmar, T. Stucky, H.-J. Scheibe (Fraunhofer Institute for Materials and Beam Technology, Germany) Tetrahedral bonded amorphous carbon (ta-C) has proved its outstanding tribological performance, but its introduction into market has been delayed by the problem to produce this promising coating with sufficient efficiency. This economic barrier can been overcome by large volume coaters as they are realizable on the base of laser-controlled pulsed vacuum arc technology (Laser-Arc). For achieving reproducible results the geometrical and kinematical conditions in such industrial coaters must thoroughly be considered: The structure of the carbon film depends (apart from particle energy) markedly on geometric factors such as angle of incidence and the relative position to the arc sources and on the surface temperature. These parameters are continuously changing due to the rotations of the parts and the linear motion of the laser-guided arc spot leading to periodically changing deposition conditons. Applying the simulation program SimCoat on a concrete industrial Laser-Arc device, the influence of the external controllable geometric and kinematical parameters on the thickness distribution and on the layered substructure of the superhard amorphous carbon film has been investigated. This theoretical screening of the multidimensional parameter field has been compared with experimental results. It is shown how the combination of simulation and experiment allows a very efficient technological optimization.
BP-1-29 The Temperature Effects on Surface Energy of PVD Coatings S-M. Chiu, T. Cho, C.W. Chu (Metal Industries R & D Center, Taiwan, ROC); Y.C. Chen (Shu-Te University, Taiwan, ROC) Although Cr plated molding dies have been using intensively in the IC industry,the sticking problems between mold surface and molding compound still remain the same as before and even become much worse due to more and more sticker compounds being used today. In our study newly developed Cr-based coating were formed on mold steels by a PVD sputtering system. Then the coating were characterize by measuring surface properties such as surface energy force "adhesion force" water droplet contact angle at ambient and/or elevated temperatures. The major findings of the study are summarized as follows: (1) temperature has a great effect on surface energy, (2) contact angles of above 110°can be obtain at ambient temperatures, and coatings become less sticky at 1000°C -8000°C, (3) new coating can effectively lessen the adhesion force of molding compound on steels, (4) on an average newly developed coatings show better molding life: i.e. the number of shots in the molding process can be increased by 50? of its original value.
BP-1-30 The Nanostructure and Mechanical Properties of PVD CrCu(N) Coatings M.A. Baker, P.J. Kench (The University of Surrey, United Kingdom); M.C Joseph, C. Tsotsos, A. Leyland, A. Matthews (University of Hull, United Kingdom) Coatings with a nanocomposite structure have been identified as offering excellent wear resistant properties [1,2]. This paper presents results on the CrCu(N) system, in which the immiscibility of Cr (with low N concentration) and Cu offers the potential of a predominantly metallic (and therefore tough) nanocomposite, composed of small Cr(N) grains interdispersed in a (minority) Cu matrix. A range of CrCu(N) compositions have been deposited using a hot-filament enhanced unbalanced magnetron sputtering system. The stoichiometry and nanostructure have been characterised by XPS, TEM, SEM, XRD and PEELS. Knoop microhardness and nanoindentation hardness (and elastic modulus) of the coatings are reported; adhesion and wear resistance have been determined using Rockwell 'C' indentation, incremental-load scratch testing, reciprocating-sliding (against SAE 52100 and WC-Co ball counterfaces) and ball-on-plate high-frequency impact. Results are presented correlating the nanostructure and mechanical properties of the CrCu(N) coatings. [1] M.A.Baker, S.Klose, C.Rebholz, A.Leyland, A.Matthews Surface and Coatings Technology (2001) - in press. [2] A.A.Voevodin, J.S.Zabinski Thin Solid Films 370 (2000) 223.
BP-1-31 Sinergistig Effect of Ar, N and Si Ion Implantation as a Surface Modification Technique to Improve Localised Corrosion of Different Stainless Steels F.J. Pérez, M.P. Hierro, C. Gómez, L. Martinez, B. Chico (Universidad Complutense de Madrid, Spain) Ion implantation is a surface modification technique which affects the surface properties without changing the bulk ones. In this work, the effect of Silicon Nitrogen and Argon implantation on different stainless steels is discussed. Silicon was implanted in order to improve the corrosion properties of those stainless steels by generating a Si- rich region near the surface. Argon, as a noble gas, is supposed that has no chemical but physical effects on the bulk. Different implantation doses (1x10¹⁴, 5x10¹⁴, 1x10¹⁵ ions/cm²) at an energy of 80KeV have been tested to optimise the implantation dose for each steel. Theoretical simulations using TRIM 96 computer code have been performed in order to estimate the depth profiles and to optimise the implantation parameters. The corrosion measurements were carried out in NaCl solution by using electrochemical impedance spectroscopy (EIS). The surface have been characterised by SEM, AES and AFM. The experimental results showed that the effect of Si and Ar implantation mainly depends on the microstructure and/or composition of the stainless steels. Less compact structures and/or less amount of alloying elements (as occurs with AISI 430) achieve bigger changes with this modification, whereas on stainless steels with a larger amount of alloying elements and/ or more compact structures (AISI 317L) ion implantation slightly modifies the corrosion behaviour.
BP-1-32 Silicon/Silicon Oxide Bi-Layer Coating on AISI 304 Stainless Steel by CVD in FBR F.J. Pérez, M.P. Hierro, M.C. Carpintero, C. Gómez, F. Pedraza (Universidad Complutense de Madrid, Spain) Silicon can be deposited and diffused on AISI 304 surfaces to increase corrosion resistance in aqueous acidic environments, high temperature oxidation and erosion resistance. This coating has been obtained by Chemical Vapor Deposition (CVD) in fluidized bed at relatively low temperatures (450°C-550°C). The deposition of silicon on AISI 304 steel can lead to the formation of interfacial silicide that may be used as low resistivity contacts gates, or Schottky barriers. However, the adherence of these coatings is not good when the amount of Si is increased. We studied the best conditions to deposit Si on AISI 304 to minimize the formed corrugated and non-adherent silicide layer. We have optimized the silicon coatings on the stainless steels at temperatures of 450°C for 60 and 120 min. On the other hand different treatment have been develop to pre-oxidize this layer in order to be the susbtrate to deposit a third layer on mullite on top.
BP-1-33 Evaluation of a Novel Six-coordinate Organometallic Precursor for CVD of Zirconium-based Coatings P. Franceschini (ETH Zürich, Universität Zürich, Switzerland); S. Zürcher (ETH Zürich, Switzerland); M. Morstein (Platit AG, Switzerland); D. Spencer (ETH Zürich, Switzerland); H. Berkea (Universität Zürich, Switzerland) The deposition of thin films of ZrN and related materials such as Zr(C,N) or Zr(O,N) by CVD has been so far performed using four-coordinate compounds like tetrakis(dialkylamido) zirconium: Zr(NR2)4 @super 1). Here we present some CVD experiments using a novel, volatile, solid six-coordinated precursor, consisting of two dimethylamido ligands and two bidentate b-diketiminato ligands around zirconium. A vertical cold-wall reactor has been employed, using Si(100) as the substrate. Several process parameters, such as substrate temperature, reactor pressure, carrier and reactant gas flow rates have been evaluated. The chemical composition of the films have been analyzed by XPS. A critical parameter for obtaining films with a reasonable nitrogen content appears to be the reactor pressure. Optimal growth rates and higher nitrogen content in the films are obtained in a substrate temperature range between 500 and 600°. ¹C. Täschner, K. Bartsch , A. Leonhardt, Surf. Coat. Technol., 61, 1993, 158.

Time Period TuP Sessions | Topic B Sessions | Time Periods | Topics | ICMCTF2002 Schedule