Papers by Keyword: Multilayer Coating

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Authors: Nataliya A. Sakharova, José Valdemar Fernandes, Marta C. Oliveira, Jorge M. Antunes
Abstract: In the present study, numerical simulations of nanohardness tests of titanium aluminium nitride (TiAlN) hard coatings with titanium and aluminium ductile interlayers were performed in order to determine the influence of interlayers of ductile metals on the overall mechanical properties of multilayer coatings. The investigation was designed to determine the role of ductile interlayers in altering the hardness value and the Young´s modulus of the multilayer coating as a whole, in comparison with a monolayer TiAlN hard coating, for the cases of composites with different numbers and thicknesses of interlayers.
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Authors: Qiang Chen, Sandra Cabanas-Polo, Ya Ping Ding, Aldo Roberto Boccaccini
Abstract: 45S5 bioactive glass (BG) based multilayer coatings on stainless steel were produced by a combination of electrophoretic deposition (EPD) and layer-by-layer (LbL) deposition. The properties of the multilayer coating were tested with different characterization methods including SEM, FTIR, XRD, laser profilometer and water contact angle measurements. Degradation and in-vitro bioactivity behaviors were tested in simulated body fluid (SBF) over different time periods. The decomposition of the coating was inhibited and the hydroxyapatite (HA) formation after short immersion period (0.5d) was confirmed. At the same time, levofloxacin, used as a model antibiotic, was incorporated into the multilayer structure for antibacterial purpose.
170
Authors: Anna P. Rubshtein, Alexander B. Vladimirov, Sergey A. Plotnikov
Abstract: A focus point in this work was the research of the influence of deposition condition on properties of CrAlC films. CrAlC films were deposited by arc sputtering technique using arc sputtering of Cr-Al target and pulse arc sputtering of graphite target at different frequency. The multilayer [(CrAlC)+(a-C)]n coatings were also obtained and investigated. Multilayer [(CrAlC)+(a-C)]n were deposited with a systematic alternation of the pair [(CrAlC)+(a-C)], where a-C is the amorphous carbon layer. The structure, mechanical properties and fracture toughness of CrAlC films depend on pulse frequencies of the graphite sputtering. With increasing pulse frequency, the film structure changes from uniformly amorphous to amorphous with nanograins, the hardness of the films increases, the critical load of crack formation and film peeling tend to decrease. It is shown that a decrease in the thickness of the layers in [(CrAlC)+(a-C)]n leads to an increase in the crack resistance.
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Authors: Rong Hong Cui, Zhi Ming Yu, Yu Ting He, Wen Jun Shu
Abstract: A kind of copper multilayer coating was prepared on stainless steel substrate using ultrasonic-electrodepositing method. The microstructure, hardness, wear resistance, adhesion and corrosion resistance of it were investigated respectively. The results show that the coating exhibits a multilayer structure and the thickness of each layer is about 0.3µm. The crystallite average diameter of it is obviously smaller than that of the ordinary electrodeposited copper coating. The diffraction peaks of Cu (200) and Cu (111) for it are obviously stronger, while Cu (220) for it is much weaker. Comparative investigations on the mechanical properties show that only the hardness of it is a little lower, whereas the wear resistance and the adhesion of it to the substrate are all evidently enhanced. The average start corrosion time of it in 20% HNO3 solution is nearly three times delayed, and the corrosion rate is obviously decreased; anode polarization curves in 3.5% NaCl solution also show that the corrosion resistance of it is greatly improved.
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Authors: Wei Yu Ho, Chung Hsien Yang, Wei Che Huang, Woei Yun Ho
Abstract: In this study, various multilayered TiN/CrN coatings were deposited on the SS316L stainless steel substrates by the cathodic arc deposition technique. By varying the turntable rotation speed, the multilayered coatings with different periodic layer thickness were obtained. The main target of this study is to enhance the corrosion resistance and electrical conductivity of the stainless steel for potential application of metallic bipolar plate of PEMFC. The results showed that all of the TiN/CrN coated samples presented a better corrosion resistance than the bare stainless steel substrate. The multi-layered coatings deposited at the 2 rpm provided the best corrosion resistance of the coated stainless steels when they were subjected to polarization test in 1M H2SO4 solution. The result of single fuel cell test shows that the TiN/CrN multi-layered coating with the best corrosion resistance is considered to be a candidate for PEMFC bipolar plate application in this study.
291
Authors: Jun Tan, Yao Chuan Qian, Ru Xin Xing, Zhong Xiang Hu
Abstract: Pb/Ni multilayer coatings, with either Pb or Ni as the top layer, were brush plated on ANSI 304 stainless steel to improve its performance as bipolar plates in polymer electrolyte membrane fuel cells (PEMFC). Surface morphology and cross-sectional microstructure of the coatings were characterized with scanning electron microscope (SEM) and optical microscope, respectively. The corrosion resistance of brush plated coatings in a simulated PEMFC environment was investigated using both three-electrode method and immersion of 300 h. Coating surfaces after the immersion were characterized with energy dispersive X-ray spectrometer (EDS). The results show that the multilayer coatings were smooth, dense, and small in grain size with clear layered structure. In the simulated PEMFC environment, the corrosion of multilayer coatings was mainly uniform corrosion. Coatings with different top layers exhibit different corrosion behaviors. Ni layer was corroded preferentially as the anode while the Pb layer was protected.
378
Authors: Dong Hwan Song, Jong Kook Lee, Dong Seok Seo, Gon Seung Yang
Abstract: Titanium-based nitride coatings on cutting tools, press molds and dies can prolong their life cycle because of superior corrosion and oxidation resistance of coatings. In this study, TiAlN/ZrN and TiCrN/ZrN multilayer coatings were prepared by R.F magnetron sputtering, and microstructural evolution and corrosion resistance of the coatings were investigated during heat treatment. The TiAlN/ZrN and TiCrN/ZrN multilayer coatings were degraded by heating up to 600 oC with formation of oxides particles on the surface. During the heat treatment, the TiCrN/ZrN and TiAlN/ZrN multilayer coatings showed the lowest corrosion current density and the highest polarization resistance at temperature range of 400 oC and 500 oC. Consequently, the TiAlN/ZrN and TiCrN/ZrN multilayer coatings showed good corrosion resistance at temperature range of 400°C and 500°C during heating.
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Authors: Mirko Sokovic, Leszek Adam Dobrzański, Janez Kopač, Ladislav Kosec
Abstract: The paper presents investigation results of tribological and cutting properties of the coatings deposited with the PVD and CVD techniques on cutting inserts made from the Al2O3 + TiC tool ceramics. Tests were carried out on the inserts made from ceramics, uncoated and PVD or CVD-coated with gradient, mono-, multilayer and multicomponent hard wear resistant coatings composed of TiN, TiCN, TiAlN, TiAlSiN and Al2O3 layers. Substrate hardness tests and micro hardness tests of the deposited coatings were made on the ultra-micro-hardness tester. It was demonstrated, basing on the technological cutting tests of grey cast iron (260 HB), that putting down onto the tool ceramics the thin anti-wear PVD and CVD coatings increases their abrasion wear resistance, which has a direct effect on extending tool life of the cutting edge.
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Authors: Chen Guang Wei, Yi Wang Bao, Xue Qiang Cao, Zhao Liu, Yuan Tian
Abstract: Although elastic modulus of ceramic coatings at elevated temperature is difficult to measure, it was evaluated in this work simply by impulse excitation tests based on the relative method that need only the measured moduli of coated sample and substrate. This novel method was demonstrated to be valid not only for the single layer coating but also for multilayer coatings.
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Authors: Takero Fukudome, Sazo Tsuruzono, Tetsuo Tatsumi, Yoshihiro Ichikawa, Tohru Hisamatsu, Isao Yuri
Abstract: An 8000 kW class Hybrid Gas Turbine (HGT) project, administered by the New Energy and Industrial Technology Development Organization (NEDO), was completed in March 2004. The targets of this project were improvement in thermal efficiency and output power by using ceramic components, and early commercialization of the gas turbine system. The ceramic components were used for stationary parts subjected to high temperature. It became clear that silicon nitride material showed significant recession under combustion gas. Kyocera and Central Research Institute of Electric Power Industry developed new EBCs to suppress this recession. These EBCs were evaluated by exposure test, heat cycle test and actual HGT engine test. One of the EBCs showed slight defects after the actual engine tests. However, all EBCs showed high corrosion resistance and good adhesion. It was confirmed that the all EBCs worked effectively.
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