Papers

ICMCTF2004 Session BP: Symposium B Poster Session

Thursday, April 22, 2004 5:00 PM in Room San Diego

Thursday Afternoon

Time Period ThP Sessions | Topic B Sessions | Time Periods | Topics | ICMCTF2004 Schedule

BP-1 A Comparitive Study of Neon and Argon As Carrier Gases in Evaporative PVD A. Davison, J.C. Avelar-Batista, A.D. Wilson (University of Hull, United Kingdom); A. Leyland, A. Matthews (University of Sheffield, United Kingdom); K.S. Fancey (University of Hull, United Kingdom) It is known that neon can Penning ionise nitrogen, and this may significantly increase nitrogen activation in plasma-assisted physical vapour deposition (PAPVD). However, little information is available with regard to the potential benefits of using neon in evaporative PAPVD and its influence on coating microstructure. In this work deposition trials have been performed using neon or argon as the carrier gases under equivalent thermionically-supported DC PAPVD conditions. The efficacy (i.e. thickness in mm of coating deposited, for each gram of material evaporated) of the coating process under PAPVD conditions was compared to that for each of the inert gases alone (i.e. with no discharge present). It was determined that, at the lowest argon pressures examined (5 mTorr) there was an appreciable decrease in efficacy, however the efficacy in neon was similar with, or without, the discharge present. By examining the fracture cross-sections it was determined that the coatings deposited in neon discharges were less dense than those deposited under equivalent argon discharge conditions. These observations were attributed to a decreased "ion plating effect" in the neon-based discharges. The reduced sputtering yield of the lighter inert gas species and type of energetic (ionised) species bombarding the growing film have been considered in this regard.
BP-2 Quality of Low-energy Ion Beam for Deposition T. Matsumoto (National Institute of Advanced Industrial Science and Technology (AIST), Japan); K. Mimoto (Osaka University, Japan); M. Kiuchi (National Institute of Advanced Industrial Science and Technology (AIST), Japan); K. Matsuyama, T. Sadahiro, S. Sugimoto, S. Goto (Osaka University, Japan) The low-energy ion beam is a promising technique for development of functional materials, electronic and optoelectronic device materials. In the ion beam deposition, particularly in the energy range below 100 eV, it is very important to investigate the interactions between incident ions and surface. The high-energy neutrals included in the low-energy ion beam have influences on the film formation, so it is necessary to detect the accurate amount of the high-energy neutrals. In this report, we measured the amount of the high-energy neutrals using the Faraday-cups, and estimated the quality of the low-energy ion beam. The low-energy ion beam system was composed of an ion source, a beam transportation section and a deposition chamber. As the low-energy ion beam was strongly affected by space-charge effect, the ions generated from the ion source were extracted at high-energy of 20-30 keV. The high-energy ion beam was mass-selected by the sector magnet and decelerated below 100 eV in front of the substrate. However, as the result of the charge exchange reaction between high-energy ions and residual gases in a drift tube, the high-energy neutrals were generated. The high-energy neutrals couldn't be controlled by magnetic and electric field, therefore, they would damage the film formation. In order to remove the high-energy neutrals from the low-energy ion beam, the ion beam was deflected with the angle of 7 degrees by electrostatic field, and transported to the deposition chamber. However, some high-energy neutrals were regenerated after deflection, and irradiated to the substrate with the low-energy ion beam. So we fabricated the Faraday-cups to measure the high-energy neutrals included in the low-energy ion beam at the substrate. From the result of accurate measurements, the percentage of the high-energy neutrals included in the low-energy ion beam was below 1.5 %.
BP-3 Effective Control for Reactive Sputtering of Optically Tunable Oxynitride Thin Films D.C. Carter, W.D. Sproul, D.J. Christie (Advanced Energy Industries, Inc.) Reactive sputtering is gaining acceptance as a viable alternative for the deposition of many useful compound thin films. The use of closed-loop control in reactive sputtering has not only improved the stability and throughput of such processes but also provided additional controls for fine-tuning the composition and properties of the films produced. Closed-loop processes for forming binary compounds, typically oxides or nitrides, have been demonstrated using a variety of feedback means including optical emission, target voltage and mass spectroscopy. For ternary compounds such as oxynitrides, however, the addition of a second reactive gas complicates the process as well as the necessary control strategy. In this study we look at the complexities of controlling a two reactive gas sputtering process. We show experimentally, the effects of competing reactions in such processes and demonstrate how this can be managed with a properly designed control strategy. With effective control we then show the advantage of such processes in the ability to tailor compositions in the deposited films. The composition control provides the means for tuning the materialâ€™s optical properties as we illustrate with measurements taken on deposited films.
BP-4 Investigation of Non-uniform Plasma Sheath during Plasma Immersion Ion Implantation X.B. Tian, S.Q. Yang (Harbin Institute of Technology); R.K.Y. Fu, P.K. Chu (City University of Hong Kong) In typical plasma immersion ion implantation experiments, the plasma is generated using external plasma sources. The plasma around the treated objects, which are frequently located in the center of the vacuum, may be non-uniform due to diffusion phenomena. For instance, the plasma density may be low at the central zone since the external plasma sources are usually distributed on the chamber wall far away from the samples. In this work, numerical simulation is performed based on to investigate the non-uniform plasma distribution. A local focusing effect is observed leading to the non-uniform implantation across the sample surface and consequently uneven treatment. For instance, on the top surface, the vertical component of the ion velocity becomes smaller compared to that in a uniform plasma environment. Our results show that the smaller the plasma density at the central zone, the more severe the plasma sheath is distorted. Consequently, the vertical component of the incident velocity becomes smaller thereby giving rise to a lower local implantation efficiency.
BP-5 Thermal Management of Substrates in Cascade Arc Assisted CVD Processing of Diamond Coatings V.I. Gorokhovsky (Arcomac Surface Engineering, LLC.); M. Shynlov (Exactatherm, Ltd., Canada) One of the critical parameters affecting the quality and deposition rate of chemical vapor deposited polycrystalline diamond coatings is the substrate temperature. Precise temperature control during deposition make it especially difficult for complex shape substrates such as dental instruments, cutting tools and machine parts. Composite powder variable conductance insulation (CPVCI)¹ composed of a metal-ceramic powder mixture has been developed as a thermal control and support media for substrates in cascade arc assisted CVD (CACVD) reactors². The thermal regime of substrates in CACVD processing of polycrystalline diamond coatings with thermal management by CPVCI thermal transfer media was investigated as a function of powder composition and thermal flux conveyed by the cascade arc plasma environment. The effect of CPVCI thermal management on the uniformity and production yield of polycrystalline diamond coatings deposited on shank shaped substrates positioned throughout the 1m long tubular reaction zone of the CACVD reactor will be discussed. ¹V.Gorokhovsky, U.S.Patent Application No. 20020059905. ²V.Gorokhovsky, U.S.Patent No. 5,587,207.
BP-7 Bilayer Thickness and Interface Quality on the Mechanical Properties of AlN/TiN Multilayer Thin Films Th. Vasco, R. Sanjines, A. Karimi (EPFL, Switzerland) Nanometer scale multilayer materials exhibit a variety of interesting structural and mechanical properties, for example greater toughness and higher hardness as compared to the rule of mixture. For the purpose of understanding the fundamental aspects of phase stability and for exploring strengthening mechanisms in such composite structures, the AlN/TiN system was chosen for investigation. The equilibrium structure of AlN at atmospheric pressure is hexagonal wurtzite, which can be transformed into zincblend or B1 rocksalt type under high pressure and epitaxial growth. In addition, AlN and TiN are immiscible at low temperatures such that sharp and stable interfaces are expected promoting large hardness enhancement at low temperature deposition. At higher deposition temperatures, however, substantial chemical reactions could occur leading to the formation of ternary alloy phases. These structural features play a major role on overall mechanical properties and fracture behaviour of multilayer thin films. By controlling the thickness of individual layers and substrate temperatures in a reactive magnetron sputtering, a number of controlled microstructures were grown. The films were characterized using grazing incidence XRD, nanoindentation (MTS system), and cross sectional TEM. Indentation induced crack modes and morphologies were also investigated using SEM and AFM together with some FIB cross section of indents. In this paper, the results will be described and discussed in terms of characteristic features of magnetron sputtering deposition conditions. Regarding fundamental aspects, several strengthening mechanisms based on the structure barrier, coherency stresses, misfit dislocations, and modulus mismatch between the layers will be presented and their relevance for AlN/TiN system will be discussed.
BP-8 Formation of Nano-composite Films by Adding Various Elements to TiAlN Coating using a Hybrid Coating System S. Kujime, K. Takahara, K. Yamamoto (Kobe Steel Ltd., Japan) Due to the recent demand for high-performance tribological coatings especially in the field of cutting tool application, addition of variety of elements such as Si, Cr etc to conventional TiAlN coating, namely nano-composite coatings, has been demonstrated. Conventional deposition method of above multi-element coating system is to use alloy targets that contain all of elements of interest. Kobe steel developed a hybrid coating system, which comprises new plasma enhanced arc sources and UBMS(unbalanced magnetron sputter) sources in the same process chamber that can be operated simultaneously or alternatively for deposition of nano-composite coatings or nano-multilayer coatings. In this work, conventional Ti0.5Al0.5N coating was deposited by arc cathode and addition of third element (Si for example) was carried out by a UBMS source. In case of Si, the doping amount can be adjusted by changing the input power to the UBMS source from 0 to approximately 6at%. These films were characterized by XRD, TEM, SEM for compositional and structural analysis and nano-indentation for mechanical properties. The result indicated that the average grain size of TiAlSiN coating was decreased from approximately 30nm to below 10nm by increasing the Si content. Addition of other elements will be demonstrated in the presentation.
BP-9 Comparative Study of the Oxidation Resistance between Ti-Al-Si-N and Ti-Al-N Coatings J.B. Choi, K. Cho (Pusan National University, South Korea); J.J. Moore (Colorado School of Mines) High-temperature oxidation behaviors of Ti-Al-Si-N and Ti-Al-N coatings were comparatively investigated in this work. These films were deposited onto silicon wafer by a hybrid coating system of cathodic arc ion plating (AIP) technique using TiAl target and magnetron sputtering technique using silicon targets in nitrogen-argon gas mixture. While the solid-solution Ti-Al-N coatings have superior oxidation resistance up to around 800°C due to migration of Al atoms toward surface region and subsequent formation of Al-rich oxide layer at surface, the quaternary Ti-Al-Si-N coatings showed further enhanced oxidation resistance due to its microstructure characterized by Ti-Al-N crystallites surrounded with amorphous silicon nitride. Thickness, composition, chemical bonding status, etc. were compared between two coatings, and oxidation mechanisms were discussed in this paper.
BP-10 Synthesis and Characterization of Quaternary Ti-Si-C-N Films Deposited by a Hybrid Coating System S.R. Choi, J.H. Jeon, I.W. Park (Pusan National University, South Korea) Quaternary Ti-Si-C-N films were deposited on WC-Co substrates by a hybrid system of arc ion plating (AIP) and sputtering techniques using Ti and Si targets, in an Ar/N₂/CH₄ gaseous mixture. The crystallinity, thickness, chemical composition, bonding status, and microstructure of the Ti-Si-C-N films were investigated with instrumental analyses such as XRD, SEM, EPMA, XPS, etc. As the Si was incorporated into Ti-C-N films, the Ti-Si-C-N film showed much enhanced hardness values of about 50 GPa with a load of 25g from one of 28 GPa for Ti-C-N film. The tribological properties of the coating layer were evaluated using a conventional ball-on-disc sliding wear apparatus. The friction coefficient of Ti-Si-C-N films against steel was also dependent on the Si content. In work, the microstructure and mechanical properties of Ti-Si-C-N films were systematically investigated.
BP-11 Material Characterization and Nanohardness Measurement of Nanostructured Ta-Si-N Film P.J. Su, C.K. Chung (National Chung Kung University, Taiwan, R.O.C.) This paper presents the exploration of correlating the process, composition, nanostructure and nanohardness of the Ta-Si-N films that have been applied in IC diffusion barrier, mechanical hard coating and potentially for sensors and actuators. Ta-Si-N films are reactively cosputtered by individual Ta and Si targets in N₂/Ar ambient and characterized by Rutherford backscattering spectrometry (RBS), grazing incident angle X-ray diffractometer (GIAXRD) and nanoindenter for the composition, nanostructure and nanohardness analysis, respectively. Increasing Si target power or decreasing Ta target power will produce higher Si/Ta ratio Ta-Si-N films with more amorphous microstructure as well as smaller nanocrystalline grains. The nanohardnesses of Ta-Si-N films measured by nanoindentation are between 13.5 and 16.4 GPa. Increasing N₂ flow will reduce the nanohardnesses while the grain size of Ta-Si-N film is not change obviously. But increasing Si composition will reduce both grain size and nanohardnesses of Ta-Si-N films.
BP-12 Structure and Mechanical Properties of the Cr-Si-N and TiAl-Si-N Films Synthesized by a Closed Field Unbalanced Magnetron Sputtering J.H. Hahn (Korea Reserch Institute of Sandards and Science, South Korea); G.S. Kim, S.D. Kim, S.Y. Lee (HanKuk Aviation University, South Korea) The current industrial interest in the hard coatings is focused on the superhard coatings with the hardness above 40 GPa, which have excellent chemical and mechanical properties than those of coatings with the hardness below 40 GPa. In this study, we synthesized Cr-Si-N and TiAl-Si-N films with various Si content using closed field unbalanced magnetron sputtering method and examined their mechanical properties such as hardness, elastic modulus, adhesion properties and wear resistance. And the lattice images and chemical compositions of films were examined by HR-TEM and GDOES, respectively, to investigate the role of Si. The results of nanoindentation test showed that the Cr-Si-N and TiAl-Si-N coatings have the superhardness above 40 GPa. Also it was observed that the wear resistance of films was largely increased not showing notable decrease in adhesion than that of the films without Si. This enhancement of mechanical properties in the Cr-Si-N and TiAl-Si-N coatings could be attributed to the Si doping effect, which has reduced the grain size of films and increased residual stress by forming amorphous phase at the grain boundary. Detailed analysis results of Cr-Si-N and TiAl-Si-N coatings will be presented.
BP-13 Synthesis and Mechanical Properties of Cr-Si-N Coatings Deposited by a Hybrid System of Arc Ion Plating and Sputtering Techniques J.H. Park, D.K. Lee (Pusan National University, South Korea) Ternary Cr-Si-N coatings, in which Si was incorporated into previous Cr-N one were synthesized onto steel substrate using a hybrid system of arc ion plating (AIP) and sputtering techniques. In the hybrid coating system, Cr-N coating process was performed substantially by a cathodic AIP technique using Cr target, and Si could be added by sputtering Si target during Cr-N deposition for Cr-Si-N coatings. In this work, comparative studies on microstructure, mechanical and oxidation properties between Cr-N and Cr-Si-N coatings were conducted. The hardness of Cr-Si-N coatings largely increased with increase of Si content up to around 9 at.%, and then gradually decreased with further increase of Si content beyond this point. Nitrogen partial pressure affected phase formation and composition of Cr-N coatings, and Si addition changed its microstructure.
BP-14 Reaction Induced Phase Separation from Supersaturated Solid Solution to Nitride in Thin Films S. Muraishi, T. Aizawa (University of Tokyo, Japan); H. Kuwahara (Research Institute for Advanced Sciences, Japan) Super saturated Ti-X alloy was prepared by ion beam sputtering deposition (IBSD). N⁺ implantation was made on this film aiming at fabrication of nano-structured materials. Ion implantation and IBSD process was a low temperature non-equilibrium process, which enable to yield the fine distribution of compounds, super saturated solid solution and amorphous. In the binary Ti-N system, N locates on the octahedral interstices of Ti sublattice and easily diffuses to react with Ti. By selecting appropriate element for X to promote the TiN formation, reaction might induce the phase separation of TiN and X phase. In this work, V and Si are chosen for X by considering the standard formation enthalpy (ΔH). These V and Si would make solid solution and siliside with Ti, respectively. Ti-12at%V and Ti-20at%Si were deposited on (001)Si substrate with 150 nm in thickness by IBSD. Structural changes were evaluated by TEM and XPS analysis. Cross sectional TEM observation revealed that as deposited Ti-V film showed the bcc structure, which indicates the solid solution of Ti-V. On the other hand, Ti-Si film showed amorphous. N⁺ with the dose of 1x10¹⁷ ion/cm² was implanted into films with the beam energy of 100 keV. Selective nitriding behavior of Ti-X films was evaluated by XPS chemical shift analysis.
BP-15 Effect of Si Incorporation on the Properties of Niobium Nitride Films M. Benkahoul, C.S. Sandu, A. Karimi, F. Lévy (IPMC, EPFL, Switzerland) Thin films of NbN-SiNx have been deposited by reactive magnetron sputtering from confocal Nb and Si targets in mixed Ar/N₂ atmosphere at a substrate temperature of 250°C. The nitrogen partial pressure and the current on Nb target were kept constant, while the current on Si target was varied in order to obtain various atomic Si concentrations in the films, between 1 and 34%. For Si concentrations below 11 at. %, X-rays diffraction reveals that the films are crystalline with fcc structure. For higher Si concentrations the films become amorphous. The grain size and morphology of the films are greatly influenced by the Si content. Nanoindentation measurements show that the hardness rapidly increases with increasing Si content up to 4 at.%, to reach a peak of 34 GPa, and decreases to the value of the reported hardness of amorphous Si₃N₄ (22 GPa) above 11 at.%. This behavior is similar to that observed in MeN- Si₃N₄ nanocomposites (Me = Ti, W, V).
BP-16 Effect of Film Thickness on the Structure and Properties of Nanocrystalline ZrN Thin Film by Ion Plating J.H. Huang, H.C. Yang, G.P. Yu (National Tsing Hua University, Taiwan, R.O.C.) Nanocrystalline ZrN thin films were successfully deposited on Si (100) and AISI 316 stainless steel substrates using hollow cathode discharge ion plating (HCD-IP) method. The objective of this study was to investigate the effect of film thickness on the composition, structures, mechanical properties of the ZrN film. The results showed that (111) was the dominant preferred orientation in ZrN films. The effects of the film thickness were significant on the N/Zr ratio, roughness, and grain size. The packing factor was only slightly varied with film thickness and the thinnest specimen reached a quite high packing factor of 0.8. Nanoindentation data indicated that hardness of the films was not related to the film texture or the residual stress. The minimum grain size required for the activation of dislocation slip in nano-sized grains was estimated to be ~85nm. The deformation mechanism of the ZrN film may be due to grain rotation or grain boundary sliding followed by mass transfer, instead of dislocation mechanism. The residual stress of all ZrN films was compressive, and did not vary with film thickness. The residual stress of the ZrN film deposited on Si is lower than that on AISI 316 stainless steel. This may be due to the difference in thermal and electrical conductivities between Si and 316 stainless steel.
BP-17 Mechanical Properties of ZrN/Ni Nanocomposite and Nanolaminate Coatings T. Maeruf, M. Debessai, K Farhang, S.M. Aouadi (Southern Illinois University) Nanocomposite and nanolaminate films of ZrN/Ni were prepared using reactive unbalanced magnetron sputtering and their structural, chemical, and mechanical properties were investigated as a function of film architecture (substrate bias, layer thickness and film composition. X-ray diffraction spectra revealed that the nanocomposites are made of nanocrystalline ZrN embedded in a Ni matrix. The grain size was evaluated using the Scherrer formula and was found to depend on deposition conditions. XRD findings were confirmed by transmission electron microscopy. The chemical and phase composition were deduced from X-ray photoelectron spectroscopy (XPS). Nanohardness and elastic modulus was measured by nanoindention. The resistance to plastic deformation, as measured by the ratio H₃/E₂, was optimized with a silver content of 15% and a substrate bias of -100 V. Finally, the tribological behavior of these films was studied using a pin-on-disk wear tester.
BP-18 Comparative Study of Quantitative In-depth Profile Techniques for Multilayer Characterisation R. Martínez, R.J. Rodríguez, G.G. Fuentes, JA García, B. Lerga, M. Rico (Asociación de la Industria Navarra, Spain); A. Guette, M. Lahaye, C. Labrugère (CeCama France) The new trends in PVD industrial coatings point out to multilayered coatings as the way of easily achieve much better tribological performances than conventional coatings. Multilayered coatings consist on several single piled up layers of good tribological properties, but having each of them thickness ranging from several hundreds of nanometers down to barely 5-10 nm. The performance of these nanolayered coatings depends strongly on the coating thickness modulation for each single layer. This paper compares the accuracy of in-depth profiles Auger Electron Spectrometry (AES), X-ray Photoelectron Spectroscopy (XPS) and Glow discharge Optical Emission Spectroscopy (GDOES), in terms of chemical quantification, in-depth resolution and analysis time. In particular, we have characterised nanolayered TiN/CrN coatings, with a total thickness of 2 microns, with different number of single layers. The reported results indicate that the three techniques (AES, GDOES and XPS) ex-hibit comparable chemical quantification, but GDS provides a much larger analysis velocity than that characteristic of the other two. Interestingly, the in-depth resolution shown by the GDOES is comparable to that of the AES and XPS. This is due to the fact that the impact energy associated to the sputtering process in GDOES is rather low, i.e. around 100 eV, hindering the appearance of strong interface atomic mixing between the single layers.
BP-19 Development of a Wohler Fretting Chart Approach to Select the Appropriate Surface Treatment T.W. Liskiewicz, S. Fouvry (Ecole Centrale de Lyon, France); B. Wendler (Technical University of Lodz, Poland) In case of application of the hard tribological coatings it is critical to predict when the substrate is reached to prevent from catastrophic consequences. Fretting wear, defined as a small displacement amplitude oscillatory motion between two solids in contact, is usually induced by vibrations. In more operating systems the elements are subjected to variable loadings implying variable displacement amplitudes. In this work fretting tests were carried out on different PVD hard coatings (TiN,TiC,TiCN,SiN) under constant as well as variable displacement amplitudes and under wide range of normal loadings. Tests were conducted in the controlled ambience with the RH =50%. A ball-against-flat specimen arrangement was analyzed. To quantify the loss of material a dissipated energy approach was applied. The wear depth extension is referred to the cumulated density of friction work dissipated during the test. A averaged accumulated density of friction energy is successively introduced to rationalize the coating lifetime. The critical energy density related to the duration of the surface treatment was introduced for each analyzed coating and the critical number of fretting cycles was established. Taking into account this critical value an equivalent Wohler-like fatigue chart was presented where the coating duration is predicted as a function of the pressure, the displacement amplitude and the coefficient of friction. The investigated hard coatings are compared independently of the loading conditions and its thickness. Finally this approach is deepened by introducing an equivalent ' Miner cumulative damage law ' to predict the coating lifetime under constant and variable sliding conditions.
BP-20 Low-energy Ion Beam Induced Chemical Vapor Deposition for Silicon-compound Films on Polymer Substrate T. Matsutani, T. Asanuma, M. Kiuchi (National Institute of Advanced Industrial Science and Technology (AIST), Japan); T. Takeuchi (Nara Women's University, Japan) Ambient temperature deposition of silicon-compound films on polymer substrate was achieved by low-energy ion-beam induced chemical vapor deposition (IBICVD) with organosilicon bubbling system. IBICVD technique is well known as a promising low temperature process, because ion impacts promote decomposition or chemical reaction of precursors. In the present study, chemical stable organosilicon precursors such as hexamethyldisilane [HMDS] and hexamethyldisiloxane [HMDSO] were used to prepare the films as gas-barrier and hard protect on polyethylene terephthalate (PET). As another advantage, low-energy IBICVD can be prepared film with smooth surface. For example, the a-SiC:H film was deposited on PET substrate at ambient temperature using IBICVD with HMDS. HMDS that was vaporized by the bubbling system, and 300 eV argon ions of ~10 µA/cm² were introduced on the substrate surface. The substrate has 100 µm thickness and the root mean square of surface roughness (RMS) of 4.4 nm measured by atomic force microscope. The RMS of the film and the film thickness was 1.6 nm and 100 nm, respectively. An infrared transmission spectra and x-ray photoelectron spectra of the film indicated formation of silicon carbide with silicon-carbon ratio of 55:45. The characteristics of the deposited silicon-compound films under several conditions will be presented.
BP-21 Effect of Ion Irradiation During Deposition on the Structure of Alumina Thin Films Grown by Plasma Assisted Chemical Vapour Deposition O. Kyrylov, D. Kurapov, J.M. Schneider (RWTH Aachen, Germany) Alumina thin films deposited by plasma assisted vapour deposition were studied with respect to the structure and composition by X-ray diffraction and electron probe microanalysis, respectively. Alumina thin films were deposited on hot work tool steel AISI H11 at a growth temperature of 500 to 600°C. The ion energy was affected by controlling the substrate power density from 2.7 to 6.6 W/cm2, which corresponds to the bias potential range from 720 to 905 V. Within the investigated process window the following characteristic phases could be identified: amorphous alumina, Γ-alumina, Α-alumina as well as mixtures thereof. The alumina phase formation was found to be strongly influenced by deposition temperature and power density at the substrate. The influence of the power density is discussed with respect to the ion energy distribution, which is estimated based on the charge exchange model of Davis and Wanderslice [1].}
BP-22 Properties of Carbon Nitride Films Produced by an Inductively Coupled Plasma Chemical Vapor Deposition D.K. Lee (Seoul National University, South Korea) Carbon nitride films were deposited on a Si (100) wafer by an inductively coupled plasma assisted chemical vapor deposition (ICP-CVD) at room temperature. A mixture of N₂ and C₂H₂ were used as the precursor. Additional rf power (13.56MHz) was applied to the substrate with various negative self bias voltages (Vself = 0 ~ -60V), and the effect of the substrate bias on the structure and properties of the films was investigated. The composition and chemical bonding of the films were analyzed by Raman spectroscopy, Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). The surface roughness of films was investigated by Atomic force microscopy (AFM). It was found that nitrogen content of films were in the range of 13.5~21.4 at%, decreased with increasing bias voltage. As the bias voltage was increased, the deposition rate decreased due to resputtering and the substrate temperature increased as a result of the energetic ions. The film hardness increased with increasing bias voltage up to 30GPa at -60V. The results from Raman and XPS analyses showed that the amount of sp³C-C or sp³C-N bonds increased with increasing bias voltage, while the number of the C-H, N-H and sp² C=N bonds decreased.
BP-23 Synthesis and Mechanical Properties of Ti-Si-C Coatings by Plasma-enhanced Chemical Vapor Deposition D.S. Han, J.H. Park (Pusan National University, South Korea) Ti-Si-C coatings where a little Si was incorporated in TiC one were synthesized by plasma-enhanced chemical vapor deposition technique using a gaseous mixture of SiH₄, TiCl₄, CH₄, Ar, and H₂. Effects of process parameters such as deposition temperature, rf power, and gas ratio, Mx = [SiH₄/(SiH₄+TiCl₄)] on the microstructure and mechanical properties were investigated. The microstructure of Ti-Si-C coatings was composite of TiC and amorphous silicon carbide from several instrumental analyses of XRD, XPS, etc. As the deposition temperature increased up to 600°C, the micro-hardness of Ti-Si-C coatings increased due mainly to diminish of residual chlorine content in the coating layer. The micro-hardness of Ti-Si-C coatings was also largely dependent on Si content. As the Si content increased to about 5 at.%, the micro-hardness of Ti-Si-C coatings increased from 20 GPa for our TiC one up to 33 GPa. It was, however, found that Si content beyond 5 at.% reduced the micro-hardness again. The effect of Si addition on the properties of TiC coatings are systematically studied in this work.
BP-24 Fabrication and Surface Treatment of Silicon Mold for Imprint Lithography S.B. Jo (INHA University, South Korea); J.K. Suh (LG Life Science, South Korea); S.G. Park, B.H. O (INHA University, South Korea) The fabrication of polymer-based microchips by imprint lithography is becoming more important as a low-cost alternative to the expensive silicon or glass-based technology. Among various applications, a silicon mold and the corresponding polymer chips of micro-array structures were fabricated for a biological application. Typical sizes of each micro structure are 500 x 500, 300 x 300, and 100 x 100 µm², respectively. The Si-wafer for a mold was etched deeply up to 40 µm with a Cr hard-mask by an etch process similar to Bosch etch process, using conventional Inductively Coupled Plasma (ICP) equipment with SF₆ based chemistry. Here, the varied etch process and complex gas chemistries are tested with various additive gases, such as Ar, O₂, H₂, and C₄F₈. As the deposition of fluorinated polymer on the surface of Si-mold increases, the stiction problem between the Si-mold and imprinted polymer was cured. The surface of released polymer chips is characterized by AFM and SEM. The coating effectiveness of the fluorinated polymers from various gases is checked, and the aging characteristics according to the repeated imprinting process are examined.
BP-25 TiC & Gr Co-Deposited Thin Films F. Kustas (Engineered Coatings, Inc.); J. Sinchak, B. Mishra (Colorado School of Mines) Transition metal carbide films offer high hardness and good wear resistance, but require a reduction in coefficient of friction (COF) to increase their tribological performance. A systematic study was performed in which amorphous carbon (a-C) was added to titanium carbide (TiC) by direct-current unbalanced magnetron co-sputtering from TiC and graphite (Gr) targets. Working gas pressure, TiC-to-Gr composition ratio, and substrate bias were varied to evaluate effects of these processing variables on film properties. Coatings were deposited onto 304 SS substrates for initial characterization using C-brale indentation, nanoindentation, and ball-on-disk (BOD) friction/wear tests. Glancing incidence x-ray diffraction and x-ray photoelectron spectroscopy were performed on selected coatings to track changes in microstructure and composition, as a function of the deposition parameters. After coating down-selection, films were fabricated on 52100 bearing steel disks for additional characterization (e.g., galling and fretting tests). Results indicate that decreasing the TiC/Gr composition ratio (i.e., higher percentage of Gr) resulted in films with a lower percentage of TiC phases, lower hardness, and lower COF. Selected films deposited onto 52100 steel exhibited improved tribological performance, including a reduction in frictional torque during galling tests (against a non-coated Al alloy) and a reduction in material transfer from non-coated Al to coated 52100 steel during simulated fretting wear tests.
BP-26 Laser-Arc-Module for Deposition of Hard Amorphous Carbon (ta-C) Coatings with Excellent Tribological Properties H.-J. Scheibe, C.-F. Meyer (Fraunhofer Institute of Materials and Beam Technology, Germany); M. Leonhardt (Fraunhofer USA); B. Schultrich, V. Weihnacht (Fraunhofer Institute of Materials and Beam Technology, Germany) Using high-current pulse-arc techniques ta-C films (Diamorâ) up to 10 µm thickness and hardness up to 60 GPa have been deposited onto steel substrates. The films are characterzied with respect to their density, elastic modulus, adhesion, surface roughness, friction coefficient and wear resistance. Due to their unique tribological properties such films are applied for wear protection with a low coefficient of friction applied on tools for dry machining and components for friction, sliding and rolling contacts. The need for coating of larger series of tools and components leads to the development of an industrial applicable deposition equipment and technology. The result is the Laser-Arc-Module (LAM) technology which can be combined with any conventional batch coater used in industry, irrespective of the manufacturer. The LAM consists of 4 components, the source chamber, the high current arc source, the ignition laser, including optic and scanner and the computer based control system. The advantages of this LAM concept is that the whole equipment and all functions of the basic coater (e.g. vacuum production, sample planetary, cleaning technology, hardcoating deposition and some more) can be used and additionally a top-layer of hard amorphous carbon can be deposited in the same batch during the same cycle. The components of the LAM, its realized combination with an industrial batch coater and the results of coated tools and components will be presented in detail.
BP-27 Temperature Dependent Tribological Properties of Low Energy N Implanted V5Ti Alloys JA García, G.G. Fuentes, R. Martínez, R.J. Rodríguez (Asociación de la Industria Navarra, Spain); J. Rius (Instituto de Ciencia de Materiales de Barcelona, Spain); G. Abrasonis, J.P. Rivière (Université de Poitiers, France) In this contribution we report on the structural and the tribological characterisation of low energy nitrogen ion implanted Vanadium Titanium (V₅Ti) alloys as a function of the annealing temperature during the bombardment process. The surface of the alloys were bombarded with N₂⁺ ions accelerated at 1.2 keV in a vacuum chamber equipped with a Kaufman type ion source. The temperature during the low energy ion implantation were 480ºC, 500ºC, and 575ºC. In this temperature range, the penetration depth reached by the implanted ions is not only exclusively ballistic, (i.e. kinetic energy dependent), but diffusion effects also play a decisive role. The structural changes can be drawn as the formation of a nitrogen layer containing a blend of pristine bcc V₅Ti and a solid nitrogen solution having an expanded bcc phase. It has been found that the temperature favours the increase of both, the thickness of the diffusion layer and the relative nitrogen content in the solid solution. We have investigated the microhardness, friction and wear coefficients of the implanted V₅Ti surfaces as a function of the annealing temperature. The reported results indicate that both hardness and wear resistance against mechanical abrasion increase as the temperature during the bombardment increases. This increment of the hardness and wear resistance could be directly correlated to the amount of the expanded phase exhibited by the V₅Ti surfaces, as observed by X-ray diffraction. The hardness and wear resistance modification upon annealing temperature are discussed in terms of the microstructure of the treated surface.
BP-28 Effects of Composition and Microstructure on the Mechanical Properties and Thermal Stability of PVD CrTiCu(B,N) Glassy-metal Coatings Deposited on AISI 316 Stainless Steel C. Tsotsos, A. Leyland, A. Matthews (University of Sheffield, United Kingdom); M. Baker (University of Surrey, United Kingdom) Hard, yet tough and resilient CrTiCu(B,N) glassy-metal coatings were deposited (over a wide range of compositions) on AISI 316 stainless steel by reactive magnetron sputtering, providing a significant improvement in sliding and impact wear resistance. All compositions showed good thermal stability after annealing for an hour at up to 600°C, with certain ones exhibiting a microhardness increase of up to 40% over the as-deposited values. Being amorphous and predominantly metallic, such coatings are expected to have an elastic modulus more closely matching that of the stainless steel substrate (compared to a typical PVD ceramic coating). A combination of a relatively high hardness and a low elastic modulus provides coatings with a high H/E ratio, which is beneficial in wear applications when deposited on low-strength steels and light alloys. In this paper TEM analysis and nanoindentation tests are performed to investigate the structure and mechanical properties of CrTiCu(B,N) coatings and their respective contributions to thermal stability and tribological performance.
BP-29 Preferred Tantalum and Chromium Texture for Wear and Erosion Applications S. Lee (US Army Armament Research Development and Engineering Center, Benét Labs); J. Mueller (US Army Armament Research Development and Engineering Center, Benét Labs); V. Lee (Rensselaer Polytechnic Institute); D. Windover (US Army Armament Research Development and Engineering Center, Benét Labs and Rensselaer Polytechnic Institute); T.M. Lu (Rensselaer Polytechnic Institute); D.W. Matson (Pacific Northwest National Laboratory) Surface growth textures of tantalum and chromium coatings were investigated to determine favorable crystalline orientation for high temperature wear and erosion protection in gun tube applications. Texture affects Young's modulus and Poisson Ratio, and mechanical behavior during high temperature and pressure operation. From symmetry considerations, random oriented grains ensure uniform in-plane and in-depth mechanical behaviors, while fiber-textured grains possess in-plane crystallographic symmetry and uniform mechanical behavior. Locally developed software was used for X-ray pole figure display and analysis. As a result of shielding from specimen substrate curvature, butterfly-shaped pole figures, which were more pronounced at low two-theta angles, were observed. Production electrolytic high contraction (HC) chromium, deposited at low bath temperature and low current density produced high (111) fiber-textured chromium. Low contraction chromium deposited at higher temperature and current density produced near-random weak (111) fiber- textured chromium. Both forms of chromium exhibited excellent wear and erosion behavior. However, randomly oriented LC chromium surpassed highly fiber-textured HC chromium in performance. Electrochemically and magnetron sputtering deposited tantalum coatings were investigated as an alternative to electrolytic chromium deposition for wear and erosion protective coatings. An electrochemically-deposited bcc tantalum coating, produced on a 20mm-diameter rifled steel liner in a eutectic molten salt solution, yielded near random crystalline orientation throughout the liner. The liner with randomly orientated tantalum grains was successfully fired 5,034 rounds. Three triode-sputtered bcc tantalum coatings were deposited on 20-mm rifled tubes under various vacuum conditions. They showed, respectively, mixed (110) and (211), (110), and (211) texture, all three specimens showed poles. The first tube was fired 1500 rounds. Laboratory planer magnetron sputter deposited tantalum coatings on electrolytic chromium on a steel plate showed perfect bcc tantalum (111) fiber texture, following the (111) fiber texture of chromium.
BP-30 Corrosion Performance of PVD-coated and Anodised Materials for the Decorative Market M. Fenker (FEM, Germany); N. Jackson (Cotelere, United Kingdom); M. Spolding (George Ibberson Ltdd, United Kingdom); P. Nicole (NAJA, La Chaux du Dombief, France); K. Schönhut (Titantec, Germany); G. Gregory (Catra, United Kingdom); P.Eh. Hovsepian (Sheffield Hallam University, United Kingdom); W.-D. Münz (Techno-Coat, Germany) The anodisation of Nb, Ti and TiAl produces a palette of intensive colours due to the interference effect of light at the thin oxide film formed on top of the metal. For commercial use of these surfaces the parts to be coloured have to be coated with a thin metallic film prior to anodisation. In our studies the deposition of Nb, Ti and TiAl coatings on various substrate materials (Al, Ti alloy, SS302, SS316) was performed by the ABS (arc bond sputtering) technique. The coated substrate materials were then anodised in aqueous 1 M citric acid solution. A palette of attractive colours could be produced depending on the anodisation voltage. The higher the voltage the thicker is the oxide film on top of the metallic film. The corrosion behaviour of the samples were studied by electrochemical corrosion tests in aqueous 0.8 M NaCl solution (pH 7). In potentiodynamic corrosion test it could be found that the thicker the oxide coating on Nb-coated Al the better is the corrosion resistance of the coated sample. In case of stainless steel SS302 substrates corrosion investigations revealed that the temperature during Nb deposition should not exceed 200°C otherwise the corrosion resistance of the SS302 is lost completely. Corrosion tests on uncoated samples show, that the open-circuit-potential of the as delivered SS302 decreases from E(SCE) = 40 mV to -220 mV when heat treated in vacuo at 400°C. This low corrosion resistance of SS302 in combination with the defects within the PVD coatings lead to specks after the anodisation of the Nb-coated parts which is not acceptable for decorative subjects. Encouraging results of immersion tests of Nb-coated and afterwards anodised Ti alloy and SS316 substrates in artificial sweat with respect to colour changes and elemental release have been found.
BP-31 The Electrochemical Behavior of Thermally Oxidized CrN Coatings on Steel by Cathodic Arc Plasma Deposition K.L. Chang, S.C. Chung, P.Y. Lim, S.H. Lai, H.C. Shih (National Tsing Hua University, Taiwan, R.O.C.) Cathodic arc plasma deposition of CrN coating has been applied in an industrial scale to improve the corrosion resistance of AISI 304 stainless steel. Thermal oxidation in air was carried out at the temperature of 500°C and 800°C for 1 hour. The effect of the thermal oxidation on the aqueous corrosion behavior of the CrN/304S assembly was investigated in this study. The composition and structure of the CrN coatings were studied by grazing X-ray diffraction (GXRD), electron probe x-ray microanalyser (EPMA), and X-ray photoelectron spectroscopy (XPS). The polarization resistance (Rp) of all samples was measured and compared in terms of a polarization resistance resulting from and electrochemical impedance spectroscopy (EIS) in a mixture of 0.5M H₂SO₄ and 1M NaCl solution. The microstructure of corroded samples was also examined by SEM. The results indicated that the corrosion resistance of CrN coated steel oxidized at 500°C was significantly reduced due to the high defect of CrN coating. On the contrast, the electrochemical behavior of CrN coated steel oxidized at 800°C shows better corrosion resistance than as-deposited steel. After thermal oxidation at 800°C, the large amount and stable oxide formed on the CrN coating enhances the corrosion protection of CrN coated steel.
BP-32 A Study of Plasma Oxidation Effects on the Corrosion Resistance of 63.5Cu36.5Zn Y.M. Chung, M.J. Jung, S.J. Lee, J.G. Han, C.G. Park, S.H. Ahn, J.G. Kim (SungKyunKwan University, South Korea) A study of the plasma oxidation and corrosion resistance mechanism of oxidized (63.5Cu36.5Zn) brass in oxygen plasma and Mattson solution is reported. Brass was exposed to pulsed oxygen plasma in given working conditions (working pressure, frequency, duty ratio, and working temperature) and the resulting surface was studied. The plasma oxidation mechanism involves oxygen radicals, and results from their strong oxidizing character. The ZnO was identified dominantly in the passive layer, in addition to precursor oxide Cu_xO, Cu₂O and CuO. Most of these oxides also form as corrosion products when brass samples are oxidised in Mattson solution.
BP-33 Corrosion Behavior of CrN Coatings Enhanced by Niobium Ion Implantation D.Y. Wang (Mingdao University, Taiwan, R.O.C.); Y.-Y. Chang, Wei Te Wu (National Chung-Hsing University, Taiwan, R.O.C.) Metal plasma ion implantation has being successfully developed for improving wear, corrosion, and physical properties of engineering materials. In this study, Nb ions were implanted into CrN films using a metal-plasma ion implantation apparatus. The ion energy of Nb ions was set at 150 keV with implantation doses of 1-2 x 10¹⁷ ions/cm². The electrochemical behavior in a 3.5 wt% NaCl solution was studied by the potentiodynamic polarization measurement and electrochemical impedance spectroscopy (EIS). It was found that the Nb-implanted CrN possesses a lower current density from potentiodynamic polarization tests than others. EIS analysis of CrN coated steels exhibit two distinct capacitance loops when implanted with Nb ions. The corrosion resistance of Nb-implanted CrN was improved by the formation of amorphous and chemically inert Cr-Nb-N phases, which lead to the increase of polarization resistances and the decrease of capacitances. At the dose of 1x10¹⁷ ions/cm², the Nb-implanted CrN possesses the best corrosion resistance due to the highest polarization resistance (2.53x10⁶Ω/cm²) and lowest capacitance (1.4x10^-5 F/cm²). Results of this study demonstrate the potential of metal plasma ion implantation in improving the corrosion resistance of the CrN coating without hampering its mechanical properties.
BP-34 Magnetic-field-assisted Pulsed Laser Deposition of Hard Coatings G. Reisse, S. Weissmantel, D. Rost (University of Applied Sciences, Germany) Recently, we have demonstrated the deposition of cubic boron nitride (c-BN) films at high growth rates by means of ion-assisted pulsed laser deposition [1]. It was also shown that well-adherent films can be obtained on Si and WC hard metal substrates by using special h-BN intermediate layers. The maximum thickness of 0.5 µm, however, was limited by the accumulation of particulates in the films. Those particulates are particles with sizes of several 100 nm that are ejected from the target in consequence of the laser action. The preparation of thicker films requires the elimination of those particulates. For that reason and as the incorporation of particulates in pulsed laser deposited films is still a general problem of the method we have investigated the possibilities to eliminate them by using inhomogeneous magnetic fields during the deposition of c-BN films. The basic idea is the separation of the ablated ions from the massive particulates by deflecting them by 90 degree in an inhomogeneous magnetic field and simultaneously using a particulate stop in the direct line between ablation spot and substrate. Thereby, our finding that more than 55 % of the ablated species are ionised at the used laser fluence of 30 J/cm² was of particular significance for its realisation. The feasibility of that method by using various arrangements of permanent magnets as well as electromagnets and coils and the properties of the c-BN films prepared in this way will be shown. Furthermore, we will show that inhomogeneous magnetic fields can also be used to increase significantly the growth rate of both c-BN and diamond-like carbon films. The experimental results are in good agreement with the simulation of the trajectories of the ablated ions taking into account the angular distribution of the ablated species which have been measured to be cos⁷. [1] S. Weissmantel, G. Reisse, Diam. Relat. Mater. 10, 11 (2001) 1973.
BP-35 Characteristics of Copper/Carbon and Nickel/Carbon Composite Films Produced by Microwave Plasma-Assisted Deposition Techniques from Argon-Methane Gas Mixtures Y. Pauleau, F. Thiery, L. Latrasse (National Polytechnic Institute of Grenoble, France); S. Dub (Institute for Superhard Materials, Kiev, Ukraine) Copper/carbon and nickel/carbon composite films have been deposited on Si substrates by combining sputter-deposition of metal and microwave plasma-assisted chemical vapor deposition of carbon from argon-methane mixtures of various concentrations. The deposition rate of films was found to vary between 10 and 25 nm/min depending on the CH₄ concentration in the gas phase. The crystallographic structure of films was identified by X-ray diffraction (XRD) techniques. Diffraction peaks of the cfc Cu phase were always detected in the XRD patterns of Cu/C films, even for films deposited from pure CH4. Diffraction peaks of the cfc Ni phase appeared in the XRD patterns of Ni/C films deposited from gas mixtures containing less than 5 % of CH₄. Diffraction peaks of Ni and Ni₃C phases were detectable in the XRD patterns of Ni/C films deposited from a gas phase containing 10 % of CH4. For Ni/C films deposited with a CH₄ concentration in the range 15-30 %, the diffraction peaks in the XRD patterns were only ascribable to the Ni₃C phase. For films deposited with CHsb 4 concentrations higher than 30 %, the XRD pattern exhibited only one very broad diffraction peak and the peak intensity decreased with increasing CH₄ concentration. The structure was essentially amorphous for Ni/C films deposited from gas mixtures containing more than 50 % of CH₄. The grain size of Cu, Ni and Ni3C was determined as a function of the CH4 concentration. The residual stresses in Cu/C films were very low and independent of the CH₄ concentration in the gas phase (or composition of films). For Ni-C films, the maximum value of compressive residual stresses was - 0.6 GPa for films deposited with 20 % of CH₄ in the gas phase (or for Ni/C films containing pure Ni₃C phase). The electrical resistivity of films determined by four point probe measurements as well as the hardness and elastic modulus of films deduced from nanoindentation measurements were studied as functions of the CH4 concentration in the gas phase.
BP-36 Thermal Stability and Microstructure Characterization of Sputtered Ni-P and Ni-P-Cr Coatings W.Y. Chen (National Tsing Hua University, Taiwan, R.O.C.); S.K. Tien (E-Pin Optical Industry Co., Ltd., Taiwan, R.O.C.); F.B. Wu, J.G. Duh (National Tsing Hua University, Taiwan, R.O.C.) Ni-P and Ni-P-Cr alloy coatings deposited on silicon substrate were fabricated by the RF magnetron sputtering technique with dual targets of electroless nickel-phosphorus alloy and chromium. To evaluate the enhancement of thermal stability with the dopant of a third element in Ni-P coating, differential scanning calorimeter (DSC) was used to identify the temperature of phase transformation. The crystallization behavior at different stages of phase transition in the DSC plot was studied by X-ray diffraction (XRD). Microstructure evolution of Ni-P based coating at the as-deposited and heat treated states were investigated by transmission electron microscope (TEM). The broad peak in the DSC plot of both Ni-P and Ni-P-Cr deposits is attributed to the grain coarsening of nickel based on the analysis of XRD and TEM. The addition of Cr atoms into Ni-P based coating not only suppresses the formation of Ni₃P but also reduces the grain size of precipitate.
BP-37 Thermal Behavior and Microhardness of Ternary Sputtered Ni-P-W Coating with Extra-high Phosphorous Content from High Deposition Rate-derived Electroplated NiP Targets J.H. Lin, J.G. Duh (National Tsing Hua University, Taiwan, R.O.C.) The ternary Ni-P-W alloy coating was fabricated by RF magnetron sputtering technique with dual targets of Ni-P/Cu and pure W. Electroplating Ni-P process was introduced to obtain the NiP compound target with extra-high phosphorous contents around 22 at%. The deposition rate as high as 23 µm/hr was achieved after modification of the processing parameters. The Ni-P-W coating with high P/Ni ratio 0.25 was successfully fabricated by electroplating with the high-P content Ni-P/Cu target. After heat treatment, the coating was strengthened by the precipitation of Ni-P compounds and solutioning of W in the crystallized Ni matrix. To evaluate the influence of excess phosphorous in this ternary coating, thermal stability and microhardness test were investigated by differential scanning calorimeter(DSC) and nanoindentation, respectively. The Ni-P-W coating exhibited a relatively higher hardness with higher P co-deposited. Improvement in thermal stability and mechanical property were revealed.
BP-38 Mechanical Properties of the Sputtered Nickel-Phosphorous-Based Hard Coatings under Thermal Annealing Process J.G. Duh, F.B. Wu, S.K. Tien (National Tsing Hua University, Taiwan, R.O.C.) Binary Ni-P and ternary Ni-P-W and Ni-P-Cr alloy molding coatings were fabricated by RF magnetron sputtering method onto steel substrate. Long term annealing upto 500°C was performed on various Ni-P-based coatings to simulate the cycling injection or press molding process in practical use. The mechanical properties including hardness and Young's modulus of the alloy coatings were evaluated by continuous-stiffness-measurement (CSM). It was observed that the ternary Ni-P-based coating exhibited a relatively high hardness around 15 GPa under 450°C long term thermal annealing, while the binary Ni-P showed appreciable degradation in hardness. The influence of the third element introduction in Ni-P coating was probed and discussed. In addition the correlation between indentation penetration depth and mechanical behavior was also analyzed.
BP-39 Studies of Niobium Thin Film by Energetic Vacuum Deposition G. Wu, A.M. Valente, H.L. Phillips, H. Wang, A.T. Wu (Jefferson Lab); T.J. Renk (Sandia National Laboratories) In order to understand and improve the superconducting performance of niobium thin films at cryogenic temperatures, an energetic vacuum deposition system has been developed to study deposition energy effects on the properties of niobium thin films on various substrates. Ultra high vacuum avoids the gaseous inclusions in thin films commonly seen in sputtering deposition. A biased substrate holder controls the deposition energy. Transition temperature and residual resistivity ratio of the niobium thin films at several deposition energies are obtained together with crystal orientation measurements and AFM inspection, and the results show that a preferred deposition energy exists around 115eV (the average deposition energy is 64 eV above the bias voltage). TEM analysis revealed single crystal structure for certain films. Oxygen content depth profile were also provided.
BP-40 Empirical Model of Plasma Electrolytic Oxidation of Aluminium in Alkaline Solutions L.O. Snizhko (Ukrainian State University for Chemical Technology, Ukraine); A.L. Yerokhin, T. Pilkington, A. Leyland, A. Matthews (University of Sheffield, United Kingdom) Applied voltage is a key factor affecting parameters of the plasma electrolytic oxidation (PEO) process and, consequently, structure and properties of the films produced. Under galvanostatic conditions of PEO, the voltage is determined by current density, electrolyte concentration and agitation conditions. In this work, an empirical model of PEO Al in alkaline media is developed, in which the voltage is linked to the above process parameters. The processes of oxide film formation, anodic and chemical dissolution and oxygen evolution are considered, taking into account diffusional limitations at the oxide-electrolyte interface. A system of logarithmic equations is proposed, which allows adequate description of the oxide film formation over a wide range of potentials and hydrodynamic conditions at the surface.
BP-42 Development of an Aqueous Sol-Gel Method for Synthesis of Nanostructured Multicomponent Mixed-oxide Silicate Materials N. Ghosh (University of Tennessee, Knoxville) The sol-gel method for synthesis of glass, ceramics, coating materials has been receiving much attentions over the last few years. In general, metal alkoxides are widely used for the synthesis of metal oxides in the sol-gel method. However, for the synthesis of multicomponent systems from single metal alkoxides, chemical homogeneity is of great importance. Different rates of hydrolysis of individual alkoxides result in chemical inhomogeneity in the product. To overcome this limitation, several approaches have been attempted, including matching of hydrolysis rates by chemical modification of chelating ligands or synthesis of multication alkoxides or partial prehydrolysis of an alkoxide. As the metal alkoxides are costly and their laboratory preparations are complex in nature, we have attempted to develop a simple, cost-effective sol-gel route for synthesis of nanostructured multicomponent silicate materials. In the present investigation, a series of multicomponent silicate systems have been prepared by using an aqueous sol-gel method, where water-sol. metal formates were used as precursors. Precipitated silica and metal formates were used as precursors and water was used as solvent. The gels prepared using these precursors were calcined at different temps. and characterized by XRD, IR, DTA and TGA. TEM was used to measure the average particle size of the calcined powders. It was observed that the average particle sizes of the powders are in nanometer scale with a narrow size distribution. In this method the replacement of metal alkoxides by metal formates and the use of water as solvent instead of alcohol, which is commonly used as solvent in all alkoxide sol-gel route facilitated the reduction of cost of the product. This processing route provides the basis for a low-cost, low-temp. method for the preparation of homogeneous nanometer-sized multicomponent ceramic powders compared with other conventional methods.
BP-43 Electrochemical and Biomedical Applications of Ta:C Film Electrode L. Lixiang (Nanyang Technological University, Singapore) DLC film made with Filtered Cathodic Vacuum Arc (FCVA) is high sp³ content ta: C film. Its mechanical and electrochemical prosperities such as good adhesion, wide potential window and low back ground current like diamond film made them suitable material as electrode material than conventional carbon based electrode. It has high signal for the trace analysis of Pb₂⁺ and Hg₂⁺ in the negative part and also provide a significant stripping response for determination of multi-metals Multi-elemental (Pb₂⁺, Cu₂⁺ and Cd₂⁺) analysis simultaneously. Electrochemical oxidation of deoxyribonucleic acid (DNA) at a conductive ta: C film electrode exhibits ta: C film electrode has well defined higher oxidation responses of guanine and adenine. DNA can be deposited at the N-DLC film electrode when the electrode is positively charged and be released when the electrode is negatively charged. The preliminary work shows that N-DLC film would be a novel electrode material for both electrochemical and biochemical detection.
BP-44 Cathodic Chromium Carbide Coatings for Molding Dies Application J. Esteve (Universitat de Barcelena, Catalunya, Spain); J. Romero, A. Lousa (Universitat de Barcelona, Catalunya, Spain); F. Muntala, L. Carreras (Tratamientos Termicos Carreras, Catalunya, Spain) Chromium carbide coating on steel is a good candidate for applications on forming and molding dies. The high mechanical strength, chemical resistance and temperature stability of Cr₃C₂ phase can be compatible with the severe abrasive wear found in these manufacture operations. Moreover the low surface energy of the coating can simplify the mold releasing operation of injected parts. We deposited chromium carbide coatings by cathodic arc evaporation from chromium targets in acetylene reactive gas. The coatings, 3 microns thick, were deposited on hardened steel probes with an adhesion interlayer thin film. The deposition conditions allowed to obtain the hard Cr₃C₂ phase and also other coatings with a controlled over-stoichiometric carbon content. The crystalline Cr₃C₂ phase has been demonstrated by XRD and the carbon excess has been quantified from the Raman G and D bands. The hardness reaches 3600 Hv in the stoichiometric carbide and decreases in the coatings with carbon excess. The tribological behavior of the coatings were tested at room temperature and at temperatures close to the conditions of the molding process. At room temperature the coatings with carbon excess shows a friction coefficient 0.12 against alumina balls, and Cr₃C₂ coatings a coefficient 0.3, but at 400°C the carbon excess coatings suffer severe wear and the stoichiometric coatings show good wear resistance.
BP-45 The Effect of the Substrate Bias Voltage on Mechanical and Corrosion Properties of Chromium Carbides Coated Steel by Fcap System C.C. Lin, K.L. Chang (National Tsing Hua University, Taiwan, R.O.C.); J.H. Lin (National Tsing Hua University, Taiwah, R.O.C.); W.J. Hsieh (National Tsing Hua University, Taiwan, R.O.C>); U.S. Chen, C.Y. Wang, H.C. Shih (National Tsing Hua University, Taiwan, R.O.C.) In a 90@degree-bend magnetic filtered cathodic arc plasma (FCAP) system, filter source is the key to a successful process to reduce macro-particles contamination and to obtain high quality films in the deposition of metal. In this study, chromium carbide films were synthesized from Cr target (99.95%) and C₂C₂ on SKD11 steel by applying a negative d.c. bias voltage to the substrate in the range -0V to -350V. The mechanical and adhesion properties were evaluated by microhardness, scratch and nanoindentation. The corrosion resistances of CrC coated steel were evaluated in aerated 3.5% NaCl solutions. The results showed that the hardness values and corrosion resistance of the CrC coated steel were improved by increasing substrate bias voltages, which is attributed to CrC film, have dense and compact microstructure at higher bias voltages. The microhardness of CrC films reaches 2298±100 HK under a 10-gf load and the films showed a thickness of 1µm and a surface roughness of 0.35nm (Rms) at a substrate bias of -250V by SEM and AFM.

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