ICMCTF2000 Session BP: B Poster
Time Period TuP Sessions | Topic B Sessions | Time Periods | Topics | ICMCTF2000 Schedule
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BP-1 Plasma Nitriding of Stainless Steel Using an ICP Source
W. Luo (Institute of High Performance Computing, Singapore); S. Xu, S. Lee (School of Science, Nayang Technological University, Singapore) A low frequency, high density, inductively coupled plasma (ICP) source has been developed and used to nitride AISI 304 stainless steel. A series of experiments has been conducted for processing time ranging from 1 to 8 hours and at bias voltage from –200 V to –800 V in a low pressure, low temperature, N2/H2/Ar plasma mixture. The thickness of the nitrided layers varies from 49 to 79 µm for various processing time at – 400 V bias voltage. It increases faster during the first nitriding hour. The microstructure, phases and composition of the nitrided surface layers are characterized by means of scanning electron microscopy/energy dispersive x-ray diffraction (SEM/EDX) and x-ray diffraction. The corrosion behavior of the nitrided layers is also studied using a potentionstat/Galvanostat instrument. It is found that the nitrided layer has crystalline structure with various phases. The distribution of the nitrogen content has a step function: high in the nitrided layer and almost zero elsewhere. The content of Cr, however, remains constant over the entire substrate/nitrided layer. After nitriding, the micro hardness of the nitrided layer is increased by a factor of 6 without loss of corrosion resistance. |
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BP-2 Deposition Environment of the Superhard ta-C Films by a Pulsed Arc Discharge Method
G.G. Kirpilenko, V.N. Inkin, A.Y. Kolpakov, A.I. Maslov (Patinor Coatings Limited, Russia); A.A. Dementyev (IRTM.RRC Kurchatov Institute, Russia) The superhard ta-C films with microhardness of 80-100 Gpa were deposited by a pulsed arc discharge method using a carbon source accelerator in vacuum of 2.10-3 - 2.10-4Pa. For stable deposition of the superhard ta-C films with excellent characteristics, there were investigated the following relations of deposition process parameters of the ta-C films: - duration of vacuum arc discharge impulse and the value of erosion coefficient and erosion pattern of graphite cathode of carbon source; - duration of discharge impulse and the value of carbon ions energy in plasma; - duration of discharge impulse and the value of internal stresses in the deposited ta-C films. At that, the value of the floating potential on the substrate during depositon of the ta-C films was determined, which allowed to estimate carbon ions energy in plasma. Besides we made analysis of the discharge initiating methods and calculation of the parameters of the linear source of carbon plasma of arc discharge method, allowing to obtain non-uniformity in thickness of the superhard ta-C films less than 7 % across the substrate area exceeding 300 cm2. Testing of the working model of the linear carbon plasma source confirmed the calculated characteristics of the source and the parameters of carbon films. Microhardness of the ta-C films was investigated by microindentor "Polyver-MET". The coefficient of friction of the ta-C films was measured by the rubbing cylinders. The ta-C films surface was examined by electronic scanning microscopy. The bonds in the ta-C films were investigated by XAES and XPS methods. |
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BP-3 Effect of d.c. Bias Voltage on the Deposition Rate for Ni Thin Films by r.f-d.c. Coupled Unbalance-magnetron Sputtering
Y. Mikami, K. Yamada (Sanyo Vacuum Industries Co., LTD., Japan); A. Ohnari, T. Degawa, T. Migita (Hiroshima Institute of Technology, Japan); H. Kajioka (Industrial Research Institute Hiroshima Prefecture West, Japan); T. Tanaka, K. Kawabata (Hiroshima Institute of Technology, Japan) The efficient preparation of ferromagnetic thin films at low gas pressure by a conventional planar magnetron sputtering with a thick target of magnetic materials is difficult because of the lower magnetic field above the target. We have developed a modified process based on an unbalanced magnetron sputtering of a magnetic Ni target (200 mm, 5 mm thick) to deposit Ni thin films by adding multiple permanent magnets around the target in the conventional magnetron sputtering system to confine the efficient plasma. The plasma confinement can be controlled by the shape of the magnetic field in the sputter deposition device with multipolar magnetic-field plasma confinement. The unbalanced magnetron discharge was generated by a 13.56 MHz r.f. source, and a d.c. power supply was simultaneously applied to the Ni target through a low pass filter in order to control the incident Ar ion energy on the target. When Ni films were prepared by changing the d.c. bias voltage from -100 V to -500 V at the r.f. power of 60 W, the deposition rate linearly increased up to 35 nm/min with the target d.c. bais voltage at the Ar gas pressure of 1.3x10-1 Pa. It was found that the film growth coefficient (deposition rate/ion current density) of Ni films was significantly influenced by the target d.c. bias voltage. The preferred Ni(111) plane, for the film deposited at the target d.c. bias voltage of -300 V, was observed from X-ray diffraction analysis and the value of the grain size estimated from the plane was about 80 nm. It was also revealed that the magnetron discharge of an unbalanced magnetron sputtering was possible at the lower Ar gas pressure of down to 6.7x10-2 Pa. |
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BP-4 Effect Of ZrCl4 Addition On ZrB2 Films Elaboration In Flowimg Ar-BCl3 Post-Discharges
J.F. Pierson, T. Belmonte, H. Michel (Laboratoire de Science et Génie des Surfaces (UMR CNRS-INPL-EdF 7570), FRANCE) Zirconium diboride films are synthesised at 733 K by a flowing microwave Ar-BCl3 post-discharges CVD process to coat Zircaloy-4 substrates with a constant thickness over 20 cm in length. The ZrB2 growth mechanism consists of a diffusion step of zirconium from the substrate to the gas-film interface where zirconium atoms react with boron chlorides to synthesize zirconium diboride 1. Zirconium chlorides, which are by-products of this reaction, are eliminated by the gas flow. Consequently, a substrate weight loss is noticed during ZrB2 film growth. ZrCl4 addition in the reactive mixture lowers significantly this weight loss by decreasing the rate of the zirconium chlorides synthesis. The zirconium diboride growth mechanism can be activated when no zirconium tetrachloride is introduced in the reactor. However, the use of a ZrCl4 flowrate affects the composition and the adhesion of the films : - Oxygen concentration in ZrB2 films is constant in the substrate when no ZrCl4 is used. This oxygen concentration decreases along the substrate when ZrCl4 is added to the reactive gas mixture. - The concentrations of the Zircaloy-4 alloying elements at the film-substrate interface are strongly dependent on the ZrCl4 flowrate. A particular attention is paid to describe the behaviour of tin (its concentration in Zircaloy-4 is about 1.4 wt %). Zirconium tetrachloride addition tends to slow down tin accumulation at the film-substrate interface. Finally, the consequences of the use of an additional flowrate of ZrCl4 on the adhesion of the zirconium diboride film are presented. 1J.F. Pierson, T. Belmonte, H. Michel, Surface and Coatings Technology, 116-119 (1999) 995 |
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BP-5 Use of Intense Pulsed Ion Beams for Materials Processing Applications
T.J. Renk, P. Provencio (Sandia National Laboratories); M.O. Thompson (Cornell University); P.G Sanders (Harvard University); K. Kasuya (Tokyo Institute of Technology, Japan) Intense pulsed high-power ion beams have been shown to produce enhanced surface properties by changes in microstructure caused by rapid heating and cooling of the surface. Additional improvements can be effected by the mixing of a previously deposited thin-film layer (surface alloying or ion beam mixing) into any number of substrate materials. We have conducted surface treatment and alloying experiments with Al, Fe, and Ti-based metals on the RHEPP-1 accelerator (maximum voltage 800 kV, dose 2-10 J/cm2) at Sandia National Laboratories. Ions are generated by the MAP gas-breakdown active anode, which can yield a number of different beam species including H, C, N, Ar, and Xe, depending upon the injected gas. Enhanced hardness and wear resistance have been produced by treatment of 440C stainless steel, and by the mixing of Pt into Ti-6Al-4V (beta-phase) alloy. Mixing of a thin-film Hf layer into Al 6061-T6 alloy (Al-1.0Mg-0.6Si) has improved its corrosion resistance by as much as four orders of magnitude in electrochemical testing, compared with untreated and uncoated Al6061. The improved wear resistance of 440C steel is evidently caused by the dispersal and reduction in size of carbide second-phase particles, as well as the formation of a lath martensite surface microstructure. In the case of the Ti alloy, the melted zone (2 microns thick) is observed to contain relatively large areas of nanocrystalline alpha-phase Ti, in which the Pt forms a metastable solid-solution. The resultant lattice strain may be contributing to the enhanced wear properties of this layer. In addition, there are enhanced numbers of dislocations extending up to 200 microns below the surface, well beyond the heat-affected zone. The mixing process has been used to measure the liquid-phase diffusion coefficient of As into Si, and various alloying metals (Mo, Sn, Zr, and Hf) into Ti. On a per-pulse basis, the diffusion in these materials appears to be quiescent during the irradiation process. We have also treated polymers and Si wafers using reduced beam power (0.5-2 J/cm2). Surface roughness of polyethylene fibers increased after treatment, resulting in increased bonding within an epoxy matrix. Melting and recrystallization of single-crystal Si was observed to be epitaxial, even after a multi-microsecond melt period. At higher beam doses (8-20 J/cm2), significant ablation and redeposition takes place. We are investigating the use of this high-kinetic energy process to form congruent thin-films of materials such as amorphous carbon and YBCO. |
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BP-6 Vacuum Electric Arc Plasma Source with Flux Separation
A. Rothem (VIP Ltd., Israel); V.M. Bashkov, A.I. Dodonov (V.I.T Ltd., Russia) Vacuum electric arc technique of coating deposition has gained wide acceptance in implementation of solid wear resistant coatings on instruments and machine parts. However, the presence of micro-particles in plasma flux ( drops of molten cathode material ) limits the technique application by forming coating irregularities, disrupting the composition and the desired coating structure. The present work relates to the development of highly efficient vacuum electric arc source with plasma flux separation. The flux separation is based on special separation of ionized and neutral (including micro-particles) plasma components by methods based on plasma-optics principles. The source allows fluxes of both gas and gas-metal plasma and provides for coating deposition at a rate of up to 40 microns/hour and the surface etching at a rate of up to 8 microns/hour with minimal plasma flux cross section of 300cm2. The coatings grain structure is much finer than that of traditional coatings, which results in higher plasticity in conjunction with high micro-hardness and high compressive stress. They are virtually non-porous and have low surface roughness. The coatings are highly adhesive to the substrate surface. Composition coatings have been obtained, including ceramics, based on metals like titanium, zirconium, tungsten and aluminum with high micro-hardness over 3000 HV and high plasticity. The functional tests proved their high efficiency, including high wear and corrosion resistance. |
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BP-7 Equipment and Technology for Plasma Coatings Deposition at Low Temperatures
V.M. Diamant (VIP Ltd., Israel); V.M. Bashkov, A.I. Dodonov (V.I.T Ltd., Russia); I.S. Semenov (NII Gozznaka, Russia) In deposition of solid wear resistant PVD-coatings the substrate temperature is one of the important factors that determine the coating quality. Usually, the substrate heating ensures high-quality coatings. However, the necessity in the substrate heating limits the use of the plasma methods. There is a wide range of articles whose heating necessarily results in their features degradation. Moreover, the temperature is often related to the energy parameters of ion or plasma fluxes restricting the control over these parameters which determine the properties of the deposited coatings. This work is related to the method, equipment and technology for deposition of plasma coatings at low substrate temperatures. The possibility to form coatings with required structure and properties regardless of the substrate temperature was proved. The TiN based coating parameters generated at low temperatures are similar to those generated by the traditional method. The results of the method and equipment use for reinforcement of coin dies surfaces (made of steels with low annealing temperature) are provided. The reinforcement coatings increase by up to 4 times the service life of the dies and improve the brightness of coins made from copper-nickel and other alloys. |
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BP-8 Computed Mean Charge State of a Biased Vacuum Arc Plasma Duct
D.T. Kwok, P.K. Chu (City University of Hong Kong); M.M.M. Bilek (University of Cambridge, United Kingdom); I.G. Brown (University of California, Berkeley, Berkeley, U.S.A.); A. Vizir (Russian Academy of Science, Russia) Vacuum arc or cathodic arc metal sources is an attractive and convenient method for depositing high quality thin metal films and metallurgical coatings. Macroparticles micrometers in size can be removed by a curved magnetic filter duct. Biasing the duct wall with a positive voltage can raise the output of the metal plasma. The metal plasma ions consist of several charge states. Time-of-flight (TOF) experiments have shown that the mean charge state will decrease with increasing biased voltage and magnetic field strength applied to the filter duct. We have computed the percentage of ions with different charge states at different biased voltage and magnetic field strength by the particle-in-cell method. It is shown that the simulated mean charge state exhibits the same dropping tendency as we increase the biased voltage and magnetic field strength. We can thus conclude that the reduction in the mean charge state is indeed a natural phenomenon of a metal plasma with multiple ion charge states. |
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BP-9 Phase Characterization of Ti1-xSixNy Nanocomposite Films
F. Vaz, L. Rebouta (University of Minho, Portugal) Recently some authors have focused their attention on the improvement of TiN properties by the addition of Si either by CVD and PVD deposition techniques. These films were characterised as being nanocomposites, consisting of cubic nanocrystallites of titanium nitride embedded in a few angstrom size amorphous matrix of silicon nitride. These coatings were claimed to have extremely high hardness, reaching values as high as 50 GPa. In the present paper we report, at first, on the preparation of samples within the (Ti,Si)N system by r.f. reactive magnetron sputtering. The second part presents results on coating microstructure as a function of Si content, obtained by XRD using both the common q-2q scans and the detector scans modes. These measurements were also used in the characterisation of texture factors and microstress states by the sin2Ψ method. Furthermore, results of EXAFS experiments together with XRD and TEM results will be used to show the development of a polycrystalline two-phase structure, and a small phase of an amorphous material surrounding the nanocrystals. The deflection method was used to evaluate the macroresidual stress states. Mechanical properties such as hardness, adhesion and wear resistance will be characterised and discussed as a function of the Si content in the Ti1-xSixNy matrix and several relations will be made concerning the most important deposition parameters. Bias voltage, deposition temperature and working gas flow will be analysed in particular detail. Regarding the preliminary results, the samples with a composition of Si between 5.9 and 10.6 at. % show the better mechanical properties, revealing hardness values more than two times higher than those of TiN. This region is also the one where the most oriented films grow (220 cubic fcc orientation) together with the smallest grains observed. Relations between mechanical properties and phase development, together with relations of structure with deposition parameters will be taken into consideration. |
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BP-10 Ion Bombardment Induced Phase Transition in Magnetron Sputtered Chromium Carbide thin Films from an Amorphous to a Crystalline Structure
S. Sattel (TZO GmbH, Germany); S. Ulrich, M. Stüber, H. Leiste, H. Holleck (Forschungszentrum Karlsruhe, Germany); M. Edinger, J. Schwan, H. Ehrhardt (Universität Kaiserslautern, Germany) Chromium carbide thin films of a composition near by stoichiometric Cr3C2 are deposited by radio frequency unbalanced magnetron sputtering (13.56 MHz) of a chromium carbide target in a pure Argon discharge. Applying an ion bombardment during film growth realized by a substrate bias voltage amorphous and crystalline coating are obtained. The formation of amorphous as well as stable and metastable crystalline structures is discussed basing on thermodynamic estimations and calculations. The phase transition from amorphous to crystalline chromium carbide is shown to be strongly influenced by the working gas pressure and the substrate bias. The correlations of both, pressure and bias, to the plasma flux parameters such as ion energy, ion current density and current density of the film-forming particles are illustrated. The plasma parameters electron temperature and charge carrier density are determined by electrical double probe measurements and correlated with the plasma potential and the ion current density. The flux of ions and film-forming particles are characterized by a system of energy and mass analysis, by a retarding field analyzer and by a faraday cup. The film composition is measured by Auger electron spectroscopy and the structure by X-ray defraction. The micro structure is correlated with the mechanical properties such as hardness (1200-3000 HV0.05), compressive stress (1-8 GPa), adhesion and friction coefficient. |
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BP-11 Nitriding of Titanium Through Nd:YAG Laser Irradiation
P. Serra, J.C. Mori, E. Martinez, J. Esteve, J.L. Morenza (Universitat de Barcelona, Spain) Nitriding of commercial Ti-6Al-4V titanium alloy by means of Nd:YAG (1.064 mm) laser irradiation in the presence of a nitrogen flow is investigated. The laser operates in continuous mode and its beam scans a planar surface line by line using galvanometric mirrors. It leads to the formation of a modified layer whose morphology, composition and properties are analyzed through several characterization techniques. In order to obtain layers of different thickness, the samples are submitted to multiple laser scans. Scanning electron microscopy shows that the surface morphology after irradiation is quite smooth, although it presents micron sized polygonal structures that suggest that melting occurred. Analysis of the cross section reveals that the thickness of the modified layer ranges from a few hundreds of nanometers to values close to 2 µm, depending on the number of laser scans. X-ray diffraction analyses indicate the presence of the cubic phase of titanium nitride in addition to a nitrogen solid solution in titanium. Compositional profiles corresponding to the elements present in the treated samples are obtained by secondary ion mass spectrometry and they reveal that oxidation is only relevant in the surface of the modified layer. The hardness of the irradiated surfaces is measured by the nanoindentation technique leading to a value up to three times higher than that of the alloy. Scratch test measurements allow to determine the critical load that a treated sample can resist before failure. This study points out that laser irradiation is a good method to nitride titanium and that multiple scans are a good way to improve the properties of the nitrided samples. |
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BP-12 Microtribological Characterization of Group V-A and VI-A Carbides Wear Resistant Coatings Effective in the Metal Casting Industry
J. Esteve, E. Martínez, A. Lousa (Universitat de Barcelona, Catalunya, Spain); F. Montala, L.L. Carreras (Tratamientos Térmicos Carreras, Catalunya, Spain) The moulds used in the metal casting and molten metal injection industrial processes can be protected with a novel thin film coating that reduces the wear of the moulds after repeated usage and greatly eases each unmoulding operation. These coatings are based on the group V and VI carbides and are obtained by plasma assisted arc deposition from the pure metal targets and methane, acethylene and argon gas mixtures. The coatings are deposited on the inner surface of the hot working steel moulds with a refractory metal thin film inter-layer. The carbide layer compositions are over-stoichiometric in carbon. These coatings have a very low chemical reactivity against molten metals and they show a low friction coefficient and a low wear rate, these last properties being enhanced when the carbon over-saturation in the carbide layer is increased. We examine the surface mechanical properties of these coatings: hardness, friction coefficient and wear rate as measured by micro-indentation and micro-scratch analysis and we relate these properties to the process parameters of the coating deposition. Finally, we discuss the mechanisms that may account for the notable performance of these coatings. |
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BP-13 Boron Carbide - Boron Nitride Multilayered Films as Wear Resistant Coatings
A. Lousa, J. Esteve, E. Martinez (Universitat de Barcelona, Catalunya, Spain) The deposition of multilayered thin film structures is an emerging coating technology that can fulfill some of the highly demanding requirements of the modern coating industry. The layered combination of two different materials may combine the specific properties of each material, and lead to an improvement of the functional properties. The multilayered structure formed by boron nitride and boron carbide alternated thin layers has shown an excellent behavior as a wear resistant coating for moderate temperature dry sliding operation. The coatings were obtained by sequential rf magnetron sputtering from a target of sintered boron carbide. Alternated layers with compositions near B4C and BN stoichiometry were obtained by controlling the N2/Ar plasma gas composition. The multilayered structure was confirmed by XPS and SIMS analysis. Films with different layer thickness between 50 and 200 nm were deposited, and the overall thickness of the multilayer was about 1 µm. The coating compressive stress was greatly reduced by controlling the different layer thickness. The micro-wear behavior of these coatings was studied under prolonged dry sliding test. The wear rate and friction analyses disclose the sequential effect of each layer in the coating |
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BP-14 Combined Sputtering and Ion-Beam-Assisted Processes for the Deposition of Carbon and Carbon Nitride Coatings
E. Bertran, F.J. Pino, M.C Polo, E. Pascual, A. Canillas, J.L. Andujar (Universitat de Barcelona, Spain) We report the preparation of amorphous carbon (a-C) and carbon nitride (a-CN) films in a hybrid plasma process that combines rf magnetron sputtering from a graphite target and ion beam bombardment from a capacitively coupled rf ion source. The films were deposited at room temperature on silicon and glass substrates placed on a rotable substrate holder which can be electrically biased. A mixture of argon and nitrogen gases was used as sputtering gas. The deposition pressure was selected around 0.1 Pa in order to make compatible the magnetron sputtering and the ion-beam processes. The effects of simultaneous bombardment with argon and nitrogen ions using different current densities and energies on the properties of the films are discussed. The composition of the films was analyzed by X-ray photoelectron spectroscopy and Secondary ion mass spectrometry. The structural properties were studied by Raman and FT-IR spectroscopies. The optical and mechanical properties, characterized by ellipsometry in the visible and the infrared range, and by nanoindentation and micro-scratch measurements, respectively, have been discussed in terms of the technological parameters and the structural properties of the films. |
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BP-15 The Epitaxial Lateral Overgrowth of Thick GaN on AlN/Si Substrate using Hydride Vapor Phase Epitaxy
J.W. Lee, H.J. Kim, J.B. Yoo (Sungkyunkwan University, Korea) Epitaxial lateral overgrowth (ELOG) of GaN is one of the promising techniques for the fabrication of optical and electronic devices. In this study, we attempt ELOG technique for growth of thick GaN on a Si (111) substrate. Because of their large lattice mismatch, the use of an intermediate layer or buffer layer is essential. For the growth of thick GaN on Si substrate the AlN layer was used to buffer layer. The AlN buffer layer of 30nm thick was deposited by RF sputtering at 500 degree C. The LT-GaN grown by HVPE at below 600 degree C was induced another buffer layer on Si substrate. The SiO2 was grown by PECVD for the use of ELOG mask on AlN buffer layer. The stripe pattern was developed along <11-20> and <1-100> crystal axis of GaN. The various stripe windows with a different spacing between stripes were developed on the SiO2 mask by conventional photolithography and wet chemical etching. The thick GaN was grown by conventional HVPE. The chlorinated gallium and ammonia were used as source gas for 'Ga' and 'N', respectively. The growth temperature of thick GaN was varied from 800 degree C to 1000 degree C. The effect of growth parameters such as AlN, LT-GaN, growth temperature, stripe patterned direction were investigated. Surface roughness and morphologies of ELOG thick GaN film were analyzed by atomic force microscopy (AFM) and scanning electron microscope (SEM). The effect of ELOG on thick GaN-film was characterized by double crystal x-ray diffractometer (DCXRD), low temperature photoluminescence (PL) and transmission electron microscope (TEM). |
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BP-16 Prototype of Cluster Tool for Copper Metallization by Filtered Vacuum Arc onto 300 mm Wafers
T. Schülke (Fraunhofer USA); W. Hentsch (FHR Anlagenbau GmbH, Germany); C. Wenzel (Dresden University of Technology, Germany); T. Witke, P. Siemroth (Fraunhofer Institute for Material and Beam Technology Dresden, Germany) Filtered arc deposition is one of the most promising candidates for an industrial PVD technology for manufacturing metallic lines and interconnections with high aspect ratios in the deep sub-micron region. Test depositions with laboratory scale devices, carried out by different groups, have shown that trenches with a width of below 300nm and an aspect ratio over 3 can be void free filled while being characterized by an excellent adhesion. High purity and a defect free microstructure are observed. To scale up this promising vacuum arc technology, a prototype-cluster tool able to process 300 mm wafers, consisting of a deposition chamber and a handling station was developed and built. In the paper, technical parameters, together with the results of first field-tests will be given. |
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BP-17 The Investigation of the Property of TiAlN Coatings by the Magnetic Filtered Cathodic Arc Deposition Technique
M-S. Leu, S.Y. Chen, Y.W. Lee, W-C. Lih, B.F. Chen (Industrial Technology Research Institute, Taiwan, ROC) A magnetic solenoid filter apparatus is employed to reduce the amount produce by the cathodic arc deposition system. However, the composition and properties of the coating deposited will be altered by such a magnetic filtering method. TiAlN coatings deposited through the magnetic solenoid filtered cathodic arc technique are evaluated in terms of surface property, color dispersion, elemental composition and oxidation behavior in the present work. Specimens corresponding to different locations in front of the source target were collected. The property obtained from the various tests performed for the specimen is found to be symmetric about the center axis of the target. In addition, specimens located along the centerline of the target are found to be higher in Ti content (28 at %) and lower in Al content (19 at %). The elemental content of Ti and Al of the coating can be correlated with its colorimetric result, demonstrating that a dark green color corresponds to a higher Al content and a red-white color corresponds to a high Ti content. Moreover, the thermogravimetric result shows an improved oxidation resistance of the coating when Al content is higher. |
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BP-18 Structural and Photoluminescent Properties of Porous Silicon with Deep Pores Obtained by Laser Assisted Electrochemistry
V. Baranauskas, M.C. Tosin, A.C. Peterlevitz, H.J. Ceragioli, S.F. Durrant (Faculdade de Engenharia Eletrica e Computacao, Universidade Estadual de Campinas, Brazil) Columnar porous silicon (PS) with deep pores is of interest for special applications such as X-ray imaging, vertical waveguides, etc. Such structures can be prepared by electrolytic etching of crystalline Si wafers with perfect control of the depth profile. In this work we report the effects of He-Ne laser irradiation during ghe electrochemical etching, on the morphological and optical properties of very thich columnar porous silicon films ( > 100 µm) . The laser treatment increases the porosity, which can influence very positively the photoluminescent properties of the PS, such that the spectra are more intense and also blue-shifted. Optical microscopy, scanning electron microscopy (SEM) micro-photoluminescence and micro-Raman spectroscopy of the surface and of the cross-section of these samples will be discussed. |
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BP-19 Textured Polycrystalline Diamond Films on Cu(111) Metal Substrates by Hot Filament Chemical Vapor Deposition
V. Mangasuli, S. Ganesh, A. Kumar (University of South Alabama) Chemical vapor deposition of diamonds on metal substrates is now a days focus of attraction in diamond film technology. In this investigations we report polycrystalline textured diamond growth on Cu(111) substrate. The diamond films have been grown by the hot filament chemical vapor deposition technique. Prior to diamond deposition Cu substrate is pretreated by excimer laser irradiaition.The structural analysis is done by X-ray diffraction, scanning electron microscopy and Raman spectroscopy. The Cu/diamond interfacial study is evaluated by transmission electron microscopy. The mechanical properties of the diamond films are evaluated by the nano-indentation technique. The details are presented in the paper.} |
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BP-20 Evaluation of Mechanical Properties of TiN/Si3N4 Bi-layered Composites
V. Mangasuli (University of Alabama); P. Nagar, A. Kumar (University of South Alabama) The most successful first generation commercial coating for wear applications is the TiN because of its high hardness, low coefficient of friction and ability to prevent build-up of metal chips to the cutting edge during machining, but inadequate high temperature stability of the coating has limited its widespread acceptance. In this paper we propose an approach to ultra-hard, nano-layered coatings in which a mixed amorphous(lubricant)/ nanocrystalline coating scheme is utilized. We have made use of Si3N4 as solid lubricant on TiN layer. The amorphous Si3N4 and crystalline TiN are grown on Si(100) substrate using the pulsed excimer laser deposition technique. The structural quality of the system has been analysed by X-ray diffraction . The mechanical properties has been evaluated by the nano-indentation technique. By the incorporation of Si3N4(a solid lubricant) on TiN, we have developed a graded coating with high hardness near the interface and a lubricious coating near the surface. This research was supported by NSF-DMII-9900459. |
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BP-21 Ti1-xAlxN, Ti1-xCrxN and Ti1-xZrxN Films Synthesized by the AIP Method
H. Hasegawa, A. Kimura, T. Suzuki (Keio University, Japan); K. Yamada (Sanyo Vacuum Industries Co., LTD., Japan) Ti1-xAlxN, Ti1-xCrxN and Ti1-xZrxN films were synthesized differing contents, x, by the arc ion plating (AIP) method and investigated on micro-Vickers hardness, lattice parameter and morphology. Further, TiN, CrN and ZrN were synthesized for comparison. The results obtained are as follow. (1) The maximum micro-hardness of Ti1-xAlxN, Ti1-xCrxN and Ti1-xZrxN films were Hv 3200 (x = 0.6), 3300 (x = 0.2) and 3000 (x = 0.5), respectively. That is, the ternary nitride films generally had own maximum hardness with respect certain x. The ternary nitride had generally higher hardness than that of binary nitrides (Hv 1400 ~ 2000). (2) The crystal structure of Ti1-xAlxN films changed from the NaCl into wurtzite type at x = 0.6 ~ 0.7, while Ti1-xCrxN and Ti1-xZrxN were kept cubic structures with all x values. With increasing contents x, the lattice parameters of Ti1-xAlxN and Ti1-xCrxN decreased monotonously from 4.23 Å (x = 0) down to 4.17 Å (x = 0.6) and 4.16 Å (x = 1), respectively. On the other hand, that of Ti1-xZrxN films monotonously increased from 4.23 Å to 4.58 Å (x = 1). (3) The surface roughness of TiN, CrN, ZrN, Ti0.5Al0.5N and Ti0.5Zr0.5N films was low with small number of droplets of ~ 4 µm, while that of Ti0.5Cr0.5N and Ti0.5V0.5N films high with large number of droplets of ~ 9 µm. |
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BP-22 Characterizations of EC-Based Coatings Obtained by Cathodic Arc Deposition
S. Anderbouhr, S. Roche, C. Ducros, L. Henry, E. Damond, P. Jacquot, F. Sanchette (Innovatique (Groupe HIT), France) Rating a large amount of carbon into the W-based coating material. The influence of four main parameters (gas atmosphere, pressure, arc current and bias voltage) on the coating composition, structural, mechanical and tribological properties has been studied. First investigations revealed that these Arc PVD films with carbon contents lower than 40 at.% consist of nanocrystalline WC grains embedded in an amorphous matrix of carbon. An optimization of hardness, friction coefficient and wear resistance may be done by adjusting the C/W ratio. The combinaison of a tribological layer and a hard underlying coating has been also investigated in order to provide both low friction and high abrasive wear resistance. The cases of X/WC(C) multilayer coating (with X = TiN, AlTiN) will be presented. |
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BP-23 Low Temperature Deposition of TiO2/CrNx Coatings on Ti6Al4V Alloys Using a Duplex Process of Unbalanced Magnetron Sputtering and Micro-arc Oxidation
X. Nie, A. Leyland, M.C. Joseph, A. Matthews (University of Hull, United Kingdom) The surface modification of lightweight metals (such as Al-, Mg- and Ti- alloys) using plasma technology is being increasingly investigated. Previous research by the authors has demonstrated that TiN, CrN, TiCN and DLC coatings can be successfully deposited on Al- and Ti-alloys using PVD, PACVD, Plasma immersion ion implantation (PI3) and hybrid combinations of these techniques. However, these coatings are unlikely to fulfil the tribological requirements of practical applications where high contact stresses occur because of an underlying lack of load support from the relatively soft substrate material. A number of techniques (e.g. anodising, thermal diffusion) can used to produce thin (i.e. ≤ 50µm) oxide coatings on titanium. However, we have recently shown that thick (i.e. > 50µm) oxide coatings on Ti- alloys can be deposited using a micro-arc discharge oxidation (MDO) technique. The hardness of the TiO2 coatings is in the range of only 650-900HV0.05 and their wear resistance is thus limited. Nevertheless, from the point of view of improving load support, a thick TiO2 coating with a hardness of around 900 HV0.05 should provide a more than adequate underlying load support layer for a low friction top coat. Therefore, a hybrid process of micro-arc oxidation and unbalanced magnetron sputtering has been investigated, in which a TiO2 layer was deposited on a Ti6Al4V alloy substrate (using MDO) for load support, and CrNx hard coatings (where x is between zero and unity) were deposited on top of the TiO2 layer for wear resistance (using magnetron sputtering). During the deposition of CrNx coatings of various compositions, the Cr target was driven by a 30kHz pulsed DC power supply with a constant target power (1kW) under a constant argon flow of 30sccm but with different nitrogen gas flow rates, at deposition temperatures of less than 2000C. The morphology and phase composition of the CrNx coatings were observed and analysed by SEM and XRD. The coating grain size and residual stress were also assessed using XRD. Mechanical and corrosion properties of the bilayer TiO2/CrNx coatings were tested. The results indicate that duplex TiO2/CrNx coatings can provide an excellent combination of good load support capacity, wear resistance and corrosion resistance (no pitting corrosion was observed in potentiodynamic tests). |
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BP-24 High Rate Deposition of Copper Thin Films Using New High Power Magnetron Sputtering Source
H.K. Park, K.H. Nam, J.G. Han, J-H. Boo (Sungkyunkwan University, Korea) We have deposited the copper (Cu) thin films on Si(100) and stainless steel substrates in the growth temperature of room temperature to 500 °C using pulsed D. C. magnetron sputtering method. An unbalanced magnetron sputtering source with high current (20 - 120 mA/cm 2) and low voltage (100 - 1000 eV) was designed and constructed for high rate deposition. Based upon the results of magnetic field simulation, we built-up the highest power (120 W/cm 2) Cu magnetron sputtering source to enhance the sputtering yield and film growth rate. The maximum deposition rate and sputtering yield of the newly developed sputtering source are 2.8 µm/min. and 70%, respectively. When an ion extraction grid was adapted between the Cu target and substrate, however, the growth rate was increased over 3 µm/min. This is 10 times higher than that of conventional sputtering method, and the sputtering yield was also reached to 80% due to low voltage and high current Cu-accelerated ions. XRD and XPS showed that highly oriented polycrystalline Cu(111) thin films with no impurity were obtained on the stainless steel substrates. During film deposition, plasma diagnostics was also carried out in situ by optical emission spectroscopy analysis. Electrical conductivity was also measured with four-point probe method. |