ICMCTF2009 Session GP: Symposium G Poster Session

Thursday, April 30, 2009 5:00 PM in Room Town & Country

Thursday Afternoon

Time Period ThP Sessions | Topic G Sessions | Time Periods | Topics | ICMCTF2009 Schedule

GP-1 Nanocomposite Coatings and Triple Coatings on High Performance Tools with Dedicated Edge Preparation A. Lümkemann, M. Morstein, T. Cselle, O. Coddet (PLATIT AG, Switzerland); V. Hajek, M. Jilek (Pivot a.s., Czech Republic); P. Karvankova (PLATIT AG, Switzerland) Optimum edge preparation can increase tool performance and -lifetime, thereby enhancing the machining process enormously. The importance of a well controlled tool micro-geometry has been proven to be nearly as important as the choice of the coating itself. Tool pretreatment reduces edge surface roughness and decreases friction between tool and workpiece. By means of a suitable edge preparation, a defined edge rounding will be achieved and edge chipping avoided during the cutting operation. Tool pretreatment must be adapted to the type of tool (inserts, drills, taps, end mills and hobs) and especially to their applications, depending on the work piece materials, cutting and machine conditions. In this contribution, dedicated edge preparation case studies will be shown for several examples of high-performance machining, such as cast iron drilling, milling of high-strength steels and dry gear cutting with HSS hobs especially for nanocomposite coatings and the new generation of PVD coatings the TripleCoatings®. The TripleCoatings® combine several advantages of conventional coatings (TiN, CrN, TiAlN, AlCrN) as of nanocomposite coatings (nc-TiAlN/a-SiN, nc-AlCrN/a-SiN). That makes TripleCoatings® applicable for both general purpose and high performance machining.
GP-2 Deposition of SiO₂ Thin Films with Dielectric Barrier Discharge at Atmospheric Pressure PECVD using PDMS/O₂/He/Ar Y.S. Kim, J.H. Lee, G.Y. Yeom (Sungkyunkwan University, Korea) The use of flexible substrates enables new applications, such as electronic devices and next generation display devices. However, one of the limitations of polymeric substrate in these applications is that oxygen and moisture rapidly diffuse through the material and subsequently degrade the electro-optical devices. To protect the flexible displays from the atmosphere, a thin film which is composed of single inorganic layer or a multilayer should be deposited on the flexible substrate of display device. SiO₂ thin films have a wide variety of electronic applications such as gate dielectrics, insulators, waveguides, etc. Atmospheric pressure (AP)-PECVD processes not only useful compared to other deposition processing conducted in vacuum but also to deposit the material uniformly over the large-area substrate by in-line processing. Among the various plasma sources operating at atmospheric pressure, dielectric barrier discharge (DBD) is one of the most promising source s for generating non-equilibrium plasmas for AP-PECVD processes. Pin-to-plate DBD (dielectric barrier discharge) is high pressure widely applied in surface modification, and thin film deposition. In this study, using the polydimethylsiloxane (PDMS) as the precursor of Si, SiO₂ thin films were deposited on plastic substrates using atmospheric plasma enhanced chemical vapor deposition (AP-PECVD) method at low temperature (< 50 ℃) and its properties were investigated. Atmospheric pressure plasma discharges were generated by applying AC voltage. The substrate was fed to the AP-PECVD system at 0.3 m/min though an in-line feeder. The increase of PDMS flow rate in the gas mixture increased deposition rate. However, it also increased impurities such as carbon group in the film and surface roughness. To have SiO₂ film at a high deposition rate with low impurity and low surface roughness, an adequate mixture of oxygen and PDMS flow rate appears to be needed.
GP-3 Cutting Performance of Cr-Al-N and Cr-Al-Mo-N Coated End-Mill Deposited by Hybrid Coating H.S. Tak (Pusan National University, Korea); S.H. Kwon (KAIST, Korea); K.H. Kim, M.C. Kang (Pusan National University, Korea) In this paper, comparative studies on the properties and cutting performance between Cr-Al-N and Cr-Al-Mo-N coated micro end-mill for ultra-high speed machining applications were conducted. Quaternary Cr-Al-Mo-N coatings were deposited on STS 304 steel and Si substrates by a hybrid coating method of an arc ion plating (AIP) for Cr target and a dc magnetron sputtering technique for Al and Mo targets under N2/Ar atmosphere. The synthesized Cr-Al-Mo-N coatings were mainly composed of a substitutional solid solution (Cr, Al, Mo)N. The maximum microhardness of Cr-Al-Mo-N coatings of 35 GPa was obtained with the Mo content of 24.2 at.%. Moreover, the friction coefficient of Cr-Al-Mo-N coatings drastically decreased from 0.9 to 0.48 with increasing Mo content from 0 to 33.2 at.% due to the formation of MoO3 which acted as a solid lubricant between the coating surface and steel ball. And then, Cutting tests were carried out to evaluate the characteristics of micro tool in vertical machining center using ultrahigh-speed air turbine spindle. Especially, the reliable evaluation system of coated tools for micro machining, where the cutting force and tool wear were simultaneously measured, was introduced.
GP-4 Effect of Ferromagnetic Module on Microcrystalline Silicon Thin Films Deposited by Internal-ICP H.-C. Lee, M.H. Jeon, K.N. kim, J.H. Lim, G.Y. Yeom (Sungkyunkwan University, Korea) Hydrogenated microcrystalline(uc-Si:H) silicon thin films prepared by plasma enhanced chemical vapor deposition (PECVD) have proven their potential on the device applications such as solar cells, thin film transistors (TFTs), sensors, etc. Especially, these crystalline silicons have great potentials in the application to active matrix organic light emitting diode because this crystalline silicon has some attractive electrical properties. The high mobility of uc-Si:H, in particular, is strongly expected for the realization of high speed devices on glass substrates. Also, due to its more rigid structure, uc-Si:H may be a solution to the increase of lifetime which is one of the significant problems of a-Si:H. In this study, the effects of internal antenna type-ICP with ferromagnetic module were investigated for the crystallization of silicon thin film during the deposition of silicon by SiH₄/H₂ and the structural properties of the thin films such as surface morphology, cry stalline fraction were studied. This uc-Si:H thin film were deposited on corning 1737 glass, silicon dioxide and single-crystal Si. The film properties were characterized using Raman scattering spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), High resolution transmission electron microscopy, (HRTEM) and I-V measurements to evaluate film crystallinity, structural image, crystal direction, and dark conductivity, respectively.
GP-5 Line-Type Internal Linear Inductively Coupled Plasma Source for Large Area Roll-to-Roll Plasma Processing J.H. Lim, K.N. Kim, G.H. Gweon, G.Y. Yeom (SungKyunKwan University, Korea) Flexible display devices are being investigated by many researchers as a potential next-generation display. Especially, roll-to-roll plasma processing is an important technique for flexible display processing. For the fabrication of flexible display devices by roll-to-roll plasma processing, not only highly uniform plasma processing but also high processing rates are required to increase the throughput of the processing. In this work, the characteristics of a line-type, internal antenna for an inductively coupled plasma (ICP) source installed with a ferromagnetic module were investigated for possible application to roll-to-roll processing of next-generation display devices. The use of 2MHz instead of 13.56MHz for the 2300mm-long ICP source improved the plasma uniformity to less than 11% along the antenna line due to the lack of the standing wave. In addition, the use of Ni-Zn ferromagnetic material in the line-type antenna improved the plasma density to about 3.1 × 10¹¹/cm³ at 3500W of 2MHz radio frequency (rf) power by confining the induced, time-varying magnetic field between the antenna line and the substrate. When the photoresist-covered glass substrate was etched at 4000W using 40mTorr and Ar/O₂ (7:3), an etch uniformity of about 5~6% was obtained along the antenna line.
GP-6 Through-Thickness Microstructural Characterization of the Plasma Electrolytic Oxidized Titanium Oxide Fabricated on Metal Titanium P.-J. Chu, A. Yerokhin, A. Leyland, A. Matthews (University of Sheffield, United Kingdom); J.-L. He (Feng Chia University, Taiwan) Titanium dioxide (TiO₂) films prepared by plasma electrolytic oxidation (PEO) on titanium have been considered for a variety of applications such as mechanical wear resistance, antimicrobial protection, photocatalytic surface functionality, bone implant biocompatibility and osteoinduction, as well as for electrode materials in dye-sensitized solar cell (DSSC) devices. PEO layers are, known to be porous, typically exhibiting both compositional and structural inhomogeneity through the layer thickness. Little attention has previously been paid to PEO layer structure at a scale less than its film thickness - particularly for the PEO-TiO₂/Ti system (for which the crystal structure over the entire layer thickness is in need of more precise determination). This study aims to explore the abovementioned knowledge gap, using several material characterization techniques. The cross-sectional morphology of the PEO layer is observed by scanning electron microscopy (SEM). Overall crys tal structural distribution through the layer thickness is examined by glancing angle X-ray diffraction (GA-XRD). Discrete crystallites in the PEO layer are characterized by transmission electron microscopy (TEM) to determine morphology and crystal structure. The results show that micrometer-scale porous anatase TiO₂ films can be synthesized, composed primarily of the anatase phase, with crystallites mostly distributed close to the substrate interface, while minor amounts of the rutile phase can be found towards the top of the layer. Microstructural and compositional evolution through the layer thickness is explained in terms of the observed process effects.
GP-7 Electron Temperature Cooling Down with Multi-Step Ionizations in an Electron Beam Generated Plasma S.H. Chae, H.Y. Chang (Korea Advanced Institute of Science and Technology (KAIST), Korea) In general, the plasma generated by an electron beam is known to have the low electron temperature. Because high energy electrons frequently collide with background gases, electrons loss their energy easily. We also consider the effect of multi-step ionizations as a reason of the low electron temperature in an electron beam generated plasma. The excited state neutrals are important in multi-step ionizations. In the experiment, the electron temperature is measured by the Langmuir probe in an Ar electron beam generated plasma. EEDF (electron energy distribution function) is obtained. The relative excited state Ar density is measured by the spectrometer. As the pressure increases, the electron temperature decreases as well as the relative excited state Ar density increases. We confirm the effect of multi-step ionizations in an electron beam generated plasma.
GP-8 Structure and Properties of Low Temperature Plasma Carburized Austenitic Stainless Steels R.M. Souza (University of São Paulo, Brazil); M. Ignat (SIMAP Grenoble INP, France); C.E. Pinedo, A.P. Tschiptschin (University of São Paulo, Brazil) Austenitic stainless steels cannot be conventionally surface treated at temperatures close to 550°C due to intense precipitation of nitrides or carbides. Plasma carburizing allows introducing carbon in the steel at temperatures bellow 500°C without carbide precipitation. Plasma carburizing of AISI 316L and 304L was carried out at 480°C, during 20 hours, using CH₄ as carbon carrier gas. The results show that a 20 microns carbon expanded austenite layer was formed on the surface. DRX results showed that the austenitic FCC lattice parameter increases from 0.358nm to 0.369nm, giving an estimation of circa 10 at. % carbon content. Lattice distortion, resulting from the expansion and the associated compressive residual stresses increase the surface hardness to 1040 HV0.025. Micro-scale tensile tests were conducted on specimens prepared with the conditions selected above, which has indicated that the damage imposed to the expanded austenite layer was more easily related to eac h separated grain than to the overall macro-scale stresses imposed by the tensile test.
GP-10 Manganese Oxide Thin Films Electrodeposited Using a Potentiodynamic Method– Effects of Potential Sweep Rates on the Material Characteristics and the Pseudocapacitive Performance M.T. Lee, J.K. Chang, Y.T. Hsieh, W.T. Tsai (National Cheng Kung University, Taiwan); C.-K. Lin (Feng Chia University, Taiwan) Manganese (Mn) oxide films were prepared by potentiodynamic electrodeposition in manganese acetate aqueous solution. Effects of the potential sweep rate on physicochemical characteristics of the deposited oxides were investigated. Surface morphologies and crystal structures of the oxides were examined using a scanning electron microscope and an X-ray diffractometer, respectively. X-ray photoelectron spectroscopic analyses were also performed to probe the chemical states. Moreover, electrochemical properties of the oxides were evaluated by cyclic voltammetry (CV). The analytical results suggested that the chemical state could be the most crucial factor that governed the pseudocapacitive performance of Mn oxide. A higher potential sweep rate led to a lower Mn valence and also to a higher hydrous state of the deposited Mn oxide. Accordingly, the oxide specific capacitance improved from 262 F/g to 337 F/g when the sweep rate of deposition potential increased from 100 mV/s t o 400 mV/s.
GP-11 SiO_x Protective and Barrier Coatings by Atmospheric Pressure Plasma Jet Deposition P. Scopece, I. Kulyk, R. Sulcis, F. Marinello, A. Patelli (CIVEN Association Venice, Italy) Atmospheric plasma superficial treatments represent an interesting alternative to vacuum systems in order to increase the on-line processing capability and to reduce costs. Industrial interests have already led to some applications in this field and in other cases results are very promising for future applications^1,2. In addition Atmospheric Pressure Plasma Jet (APPJ) can selectively treat specific part of a sample and can be used in the coating of 3D substrates. In this work we present the results on thin layers deposition of silica obtained by APPJ. By varying the deposition parameters silica coatings were studied both as anti-corrosive layers on iron samples and as gas-barrier layers for polypropylene substrates. Coating thickness have been evaluated by means of stylus profiler measurements and a good control at the nanometer scale has been obtained by varying the plasma jet speeds. Composition of the coatings was analyzed by mean of FT-IR and ATR spectroscopy, while coating morphology and modifications have been characterized by Scanning Electron Microscope (SEM). Corrosion behavior was characterized by mean of Electrochemical Impedance Spectroscopy (EIS) and a comparison with a salt spray test is presented. Finally, studies on gas permeation behavior of coated samples were performed by measuring the CO2 and O2 transmission rate and results related to the influence of the number of coating layers and to the precursor amount are also presented. ¹M.J. Shenton, M.C. Lovell-Hoare, G.C. Stevens, J. Phys. D: Appl. Phys. 2001, 34, 2754. ² 2M.J. Shenton, G.C. Stevens, J. Phys. D: Appl. Phys. 2001, 34, 2761.
GP-12 Multi-Layer Coatings of Aluminum for Corrosion Resistance and Electromagnetic Shielding J.-H. Chen, Y.-J. Fang, H.-T. Hsu, T.-J. Yang (Feng Chia University, Taiwan) Since aluminum and its alloys are, by far, the most common of the light metals, naturally most of the information deals with aluminum finishing. Anodizing of aluminum provides better corrosion resistance, but causes electromagnetic interference (EMI) problem. An attempt has been made in this study to relate the corrosion resistance and EMI shielding of aluminum by multi-layer coatings. Non-porous barrier film and porous film of aluminum oxide can be produced by anodizing aluminum in 5 wt% oxalic acid solution at 15°C for 4 hours. Nickel ions were absorbed in porous film and reduced subsequently by hydrogen gas at 500°C for two hours. Nickel atoms distributed inside porous film were acted as active sites for electroless nickel plating with dimethyl amine borane (DMAB) reducing agent. As the surface of porous film was covered by Ni-B coating, multi-layer of Ni-B/Cu/Ni-P coatings was prepared by electroless plating method and responsible for EMI shielding. The measured decibels attenuation (dB) is greater than 30 in the frequency range 900-1800 MHz. The corrosion potential (Ecorr) and corrosion current (Icorr) are – 726.5 mV (vs. Ag/AgCl) and 0.3134 µmA/cm², respectively, based upon the electrochemical analysis of anodized aluminum. Microstructures of multi-layer coatings were examined by FE-SEM and EDS analyses.
GP-13 Characterization and Photocatalytic Activity of Composite V-TiO₂/ITO Thin-Film Electrode C.Y. Chang (Mingdao University, Taiwan); M.Y. Chang (National Chung-Hsing University, Taiwan); Y.H. Hsieh (Mingdao University, Taiwan); Y.S. Wang (National Dong Hwa University, Taiwan) The object of this study is to modify the TiO₂/ITO photocatalytic electrode with vanadium. The V-doped TiO₂/ITO photocatalytic electrodes were synthesized by sol-gel method and dip-coating method. Both TiO₂/ITO and V-TiO₂/ITO photocatalytic electrodes were characterized by Field emission scanning electron microscope（FE-SEM）, Electron spectroscopy for chemical analysis system（ESCA）, X-ray diffractometer（XRD）and Isoelectric point（pHIEP）. The photocatalytic and photoelectrocatalytic activities were evaluated by the degradation of methylene blue under different parameters. The results of the external analysis of SEM, ESCA and XRD, the particle size of the TiO₂/ITO photocatalytic electrode is about 30 nm and mainly anatase structure. The particle size of V-TiO₂/ITO photocatalytic electrodes is not uniform with the size range, from 10 nm to 100 nm. The 0.30VT-I photocatalytic electrode has the best ability both on the adsorpt ion and photocatalytsis. Even in the visible light system, the 0.30VT-I photocatalytic electrode has great photoactivity as same as in the UV light system. The V-doped TiO₂/ITO photocatalytic electrodes may convert N-type semiconductor into P-type semiconductor. Applied potential 0.300V would effectively increase the photoelectrocatalytic activity.
GP-14 Plasma Processing Efficiency in Pulse Plasma System M. Zlatanovic, I. Popovic (Faculty of Electrical Engineering, Serbia) A significant advance in plasma surface processing of materials due to application of pulse power supply was introduced such as enhanced discharge stability, independent control of old and new process parameters, deposition and synthesis of new materials, enhanced reproducibility, better control of structure and morphology of deposited coatings and development of new surface treatment processes. Pulse plasma provides reliable operation but a new type of unhomogeneity due to periodic transition to the stationary state may result in non homogenous surface properties caused by “plasma spreading” effect. Number of adjustable system parameters is quite large and their influence on process efficiency is often opposite. It was found that the increase of pulse frequency results in decreased process efficiency, but on the other hand it leads to decreased gas discharge instabilities occurrences and provides more stable operation. From detailed analyses of plasma nitriding pro cess it was concluded that the compromise between the process efficiency and process stability is necessary. Based on the measurements, a variable voltage controlled impedance gas discharge electrical model was introduced. The model include different discharge electrical behavior during the process of the gas discharge spreading over the cathode surface and the process of gas discharge transition to the stationary state. The simulation results have shown that the dynamic as well as static gas discharge properties influence the shape of the pulse plasma electrical system response. The overall process efficiency was estimated through the optical emission signal analysis, since the data on the active species generation responsible for physical and chemical processes in the discharge are stored in optical emission signals. The stationary state concentration of the excited active species for nitriding process cannot be attained in the case of high frequency and low duty cycle puls ed plasma, which resulted in less efficient chemical processes on the cathode surface. Charge particles generation is related to pulse power characteristics and is strongly influenced by generator properties, interconnection line and the most significantly, on the vacuum chamber properties including workpiece shape and physical properties. The results of thermochemical plasma processing of two steel grade samples in nitrogen containing discharge were presented.
GP-15 Effects of Pressure on Physical Properties of Amorphous Carbon Film K. Kayama, M. Watanabe (Keio University, Japan); H. Kodama (Kanagawa Academy of Science and Technology, Japan); T. Suzuki (Keio University, Japan) It is expected that amorphous carbon films will be used for mechanical components especially to sliding parts because of their excellent properties such as high hardness, high wear resistance and low friction. In general, amorphous carbon films are synthesized under low pressure (under 10 Pa), but this technique costs much for vacuum devices etc. Therefore, it is necessary to realize low-cost and high-speed synthesis in order to expand application of the film. In this study, we designed and set up plasma CVD equipment where carbon films are synthesized under sub-atmospheric pressure (1 kPa -101 kPa). In order to synthesize the films, plasma was generated by dielectric-barrier discharge method and acetylene and nitrogen mixture gas were introduced under nitrogen environment. The surface of the films was observed by SEM and AFM, the hardness of the films was measured by nano-indentation test.
GP-16 Control of Plasma Non-Uniformity in Large Area / Very High Frequency Capacitive Discharges S.K. Ahn, B.K. Na, H.Y. Chang (Korea Advanced Institute of Science and Technology, Korea) To control the plasma non-uniformity induced by the electro-magnetic effects in large area / very high frequency capacitive discharges, various power feeding methods were tested in a rectangular capacitive discharge driven at 90 MHz (20 x 30 cm electrodes). Spatial electron density distributions for the power feeding methods were measured using spatially resolved rf compensation Langmuir probe. From the measurement, we found that plasma uniformity can be controlled by the number of power feeding points and spatial position of each feeding points. In addition, we also found that phase differences between each feeding points significantly affect the plasma uniformity. Variation of the plasma uniformity depending on the power feeding methods can be understood as a result of changes of electromagnetic field distribution between electrodes.
GP-17 Photoelectrocatalytic Degradation of Sodium Oxalate by TiO₂/Ti Thin-Film Electrode T.C. Cheng (Mingdao University, Taiwan); Y.H. Hsien (National Chung-Hsing University, Taiwan); K.S. Yao, Y.Y. Chen, Y.C. Yen, C.Y. Chang (Mingdao University, Taiwan) The TiO₂ thin film was deposited on the titanium plate by chemical vapor deposition (CVD) method. The photoelectrocatalytic degradation of sodium oxalate was investigated by prepared TiO₂ thin film reactor with additional electric potential at 365 nm radiation. The batch system was chosen in this experiment and the controlled parameters were pH, different supporting electrolytes, applied potential and initial Na₂C₂O₄ concentration were examined and discussed. The results revealed that the additional applied potential in photocatalytic reaction could prohibit recombination of electron/hole pairs but the photoelectrocatalytic effect was decrease when the applied potential was over 0.25 V. In additional, the various electrolytes increased the removal of sodium oxalate while the sodium sulfate (Na₂SO₄) had the most significant effect on photoelectrocatalysis. The better photoelectrocatalytic degradation of sodium oxalate occurred at pH3 when comparing the pH influence.
GP-18 Effect of Additives and pH in H₂O₂-Based Slurry on Cu-CMP Corrosion Behavior C.-C. Hung, W.-H. Lee, S.-C. Chang (National Cheng Kung University, Taiwan); Y.-D. Juang, Y.-L. Wang (National University of Tainan, Taiwan) Copper metallization is achieved by combining dual damascene process with tantalum base diffusion barrier layer with chemical mechanical polishing (CMP) to remove excess metals. For an effective application of CMP to 65-nm device fabrication, a complete investigation of the polishing behavior of copper continues to be important because CMP is a highly complicated process. The fundamental mechanism of chemical and mechanical phenomena between the wafer and the slurry is still not fully understood. In this study, effect of additives and pH of H₂O₂-based slurry on copper corrosion behavior was investigated by dc polarization techniques. The results reveal that different additives and pH value had a strong influence on the electrochemical behavior of copper corrosion.
GP-19 Effect of Plasma Nitriding Pre-Treatment on D2 Steel Surface Deformation Under Nitride Based Multilayer AIP Coating T. Okude, D. Yasunaga, K. Yamamoto (Kobe Steel Ltd., Japan); T. Kashi, K. Imai (Koshuha All Metal Service CO., Ltd., Japan); T. Takazawa, J. Yoshida (Nippon Koshuha Co,. Ltd., Japan) Nitride based AIP coatings are used as a surface treatment of stamping molds for ultra high-tensile steel sheet. Comparing with the conventional VC, TiC forming thermal diffusion processes, thermal distortion of the molds is significantly minimized during the lower temperature AIP processes. In some cases, however, deformation of the mold surface under the AIP coating occurs during the steel sheet stamping that causes film cracking resulting in insufficient life time. Plasma nitriding processes were applied to D2 steel samples as a pre-treatment of nitride based multilayer AIP coating (BELCOAT-SS¹) in order to develop duplex technology that prevents the deformation of the D2 steel mold surface under the AIP coating. Scratch test was used to investigate the deformation of the substrate surface that causes AIP film cracking. Temperature, bias voltage and treatment time of the plasma nitriding processes were controlled to optimize the surface property. Maximizing nitroge n penetration depth and minimizing iron nitride formation are found to be essential to increase film cracking critical load in the scratch test that was improved up to 160 %. ¹http://www.kobac-us.com/belcoat.html
GP-21 Characterization of Cuprous Oxide Films by Using Atmospheric Pressure Nitrogen Plasma Torch H.-Y. Chen, M.-W. Tsai, C.-H. Tsai (National Kaohsiung University of Applied Sciences, Taiwan) The Cu films were deposited onto glass by magnetron sputtering, after that the films were treated by using atmospheric pressure plasma torch with different nitrogen/oxygen ratios at 500°C for 10 min. X-ray diffraction patterns showed the as-deposited Cu films were (111) and (200) orientations. The cuprous oxide peaks appeared below nitrogen plasma torch containing 100 ppm oxygen, while additional cupric oxide peaks showed up above 1% oxygen. The as-deposited Cu films were nano-crystallites feature and the large grains were found after plasma treatment. The optical bandgap of cuprous oxide phase was 2.3 eV and 2.1 eV for cupric oxide phase. The resistivity of cuprous oxide was 2.9 Ω-cm and cupric oxide phase was 0.9 Ω-cm, which are consistent with the literature reports.
GP-22 Mechanical Properties Evaluation of Chromized Tungsten Carbide-Cobalt Hardmetals J.-L. Li, J.-W. Lee, Y.-T. Lin, C.-J. Wong (Tungnan University, Taiwan) Chromizing treatment has shown promising potential applied in mechanical industry due to the excellent corrosion and mechanical properties provided by this process. However, the application of chromizing process on the tungsten carbide-cobalt hardmetals has never been reported elsewhere. In this work, the pack chromization process has been adopted on tungsten carbide-cobalt hardmetals to produce a chromium contained hard surface layer. The SEM and XRD were employed to analysis the surface and cross-sectional morphologies and crystalline phases of chromized materials, respectively. The mechanical properties of the chromized tungsten carbide-cobalt hardmetal were evaluated by a nanoindenter, Rockwell C hardness tester and a scratch tester. It was observed that the chromizing layer was around 2 to 10 μm in thickness, which consisted of the (Cr,Fe) ₂N _1-x and (Cr,Fe) ₂₃C ₆ phases in the outer layer and an (Cr,Fe) ₂₃C ₆ phase in the inn er layer after the chromization process held at 950 20°C for 1 to 9 hrs. The hardness of the chromized hardmetals was improved effectively. The adhesion quality of the chromized tungsten carbide-cobalt hardmetal was influenced by the thickness of the surface layer.
GP-24 Synthesis of SiO_x Films on Polycarbonate Substrates under Atmospheric Pressure M. Noborisaka (Keio University, Japan); H. Kodama (Kanagawa Academy of Science and Technology, Japan); T. Suzuki (Keio University, Japan) In order to use polymer materials for vehicular windows, it is necessary to improve hardness, scratch resistance and weatherability. In general, hard thin films are coated on top of the surface such as SiO_x films which is highly transparent and have scratch resistance. Needless to say, for the low cost, it is necessary to realize SiO_x synthesis at high-speed and low-cost to large area. The atmospheric pressure plasma CVD technique using dielectric barrier discharge (DBD) is an ideal and suitable method for this purpose. In this study, we synthesized SiO_x films on PC substrate using trimethylsilane and oxygen mixture gas for process gas. Hardness of the films was measured by nano indenter and structure was analyzed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy.
GP-26 Low Temperature Treatments for Improving Sputtered ZrO_x Dielectric by High Pressure O₂ and O₃ Passivation S.-C. Chen, T.-C. Chang, H.-H. Su, C.-C. Huang, P.-C. Yang, H.-C. Huang, D.-S. Gan, N.-J. Ho (National Sun Yat-Sen University, Taiwan) In this study, we proposed the low temperature (150°C) oxygen (O₂) and ozone (O₃) treatments with high-pressure of 1000 psi to improve electrical properties of sputtered zirconium-oxide (ZrO_x) thin-film dielectric. Based on X-ray photoelectron spectroscopy (XPS) analyses, the increase of bonding energy of Zr-O and after O₂ and O₃ treatments was attributed to the reduction of traps in dielectric film. In addition, the leakage currents after treatments were also can be suppressed because the leakage mechanism was transferred from trap-assisted tunneling to Schottky-Richardson emission. From the experimental results, O₃ produced by UV light illumination in O₂ ambient has the superior passivation ability than O₂ resulting in the better improvements for electrical characteristics.
GP-28 Effect of Low-Temperature Supercritical Fluid Technology Treatment on the Performance of ZnO TFTs M.C. Chen, T.-C. Chang (National Sun Yat-Sen University, Taiwan); G.-W. Jhang, Y.-H. Tai (National Chiao Tung University, Taiwan) In this paper, the method of the low temperature supercritical fluid technology treatment was successfully applied to improve the electrical characteristics of sputtered ZnO TFT. The experimental results indicated that on/off current and threshold voltage of the device were greatly improved. According to X-ray photoelectron spectroscopy (XPS) analyses, the improvements were attributed to the increase of binding energies of Zn-O bonds and the reduction of traps at the grain boundary in ZnO thin films. In addition, the structural, optical properties and surface topography of ZnO thin films using X-ray diffraction (XRD), Photoluminescence (PL) and atomic force microscopy (AFM) were also investigated.
GP-29 Surface Modification with Borane Clusters: Superior Protection of Metal Surfaces Against Corrosion T. Base (Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Czech Republic); M.G.S. Londesborough (Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i.); J. Bould (Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Czech Republic) The tarnishing of silver causes technical problems for various hi-tech applications such as, for example, silver telescopic mirrors. Recently, we have reported on the interactions between thiolated carborane clusters with high dipole moments and gold surfaces.¹ In this contribution particular attention will be paid to the following carboranethiol species: 1,2-(HS)₂-1,2-C₂B₁₀H₁₀ (compound 1) and 9,12-(HS)₂-1,2-C₂B₁₀H₁₀ (compound 2), and their use as modifiers of silver coatings. In a recent study of ours, modified silver surfaces were exposed to H₂S and their corrosion was monitored using several techniques including UV-Vis and X-ray photoelectron spectroscopies, and Rutherford Back Scattering. We have shown that compound 2 can be effectively used as a protective mono-molecular layer to provide silver surfaces with enhanced stability against corrosion.² Both derivatives when immobiliz ed on silver surfaces are very stable towards heating and remain unchanged up to 400°C. Additionally they exhibit remarkable stability towards X-ray radiation. The stability of these species on the silver surface is the result of their unique electronic structure and molecular geometries. Compounds 1 and 2 have dipole moments of 4.1 D and 5.9 D respectively, and this character will be discussed in association with their behavior during the corrosion process. We will also provide a basis for the comparison of compounds 1 and 2 with organic thiols. Aside to the chemical protection of surfaces, modification with boron clusters can also add various other advantageous features to surfaces. We have shown recently that several metallaborane clusters can selectively and reversibly uptake and release small molecules of gases such as O₂, CO, SO₂ and others, and can potentially be used as colorimetric sensors.³ Additionally, larger boron clust e rs, such as syn and anti isomers of B₁₈H₂₂,⁴ can be used as fluorescent labels. Results describing our effort to immobilize these functional molecular clusters will also be presented.

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