Papers by Author: Shih Kang Tien

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Authors: Shih Kang Tien, Chih Hsiung Lin, Yan Zuo Tsai, Jenq Gong Duh
Abstract: CrAlSiN hard coatings were fabricated on the Si substrate from metallurgical Cr0.45Al0.45Si0.10 alloy target by reactive r.f. magnetron sputtering. The oxidation resistance of CrAlSiN coatings was investigated after annealing at temperatures between 900 and 1100°C for 1 hr in air. The phase identification and microstructure of CrAlSiN coatings after heat treatment were analyzed by X-ray diffraction (XRD). The hardness of CrAlSiN coating after heat treatment at 900oC for 1hr in air is slightly decreased from 30.2GPa to 28.3±1.3GPa, which was caused by the thin oxide formation on the surface of the film. The microstructure of CrAlSiN coating after heat treatment at 1000oC from 1 hr analyzed by TEM revealed two types of layer feature, including the nanocrystalline grain embedded in the Al-riched amorphous layer and reaction interface with relative high content of Si.
Authors: Shih Kang Tien, Fan Bean Wu, Jenq Gong Duh
Abstract: Ni-P-W composite deposit on the mild steel substrate was derived by the electroless process. The composition of the eletroless coating was Ni-10.7wt.%P-8.7wt%W analyzed by electron probe microanalysis (EPMA). The coating was annealed at various temperatures from 350oC to 600oC for 4h and the structure at different heat-treated temperature was studied by X-ray diffraction, and transmission electron microscope (TEM). The crystallization behavior was evaluated by the differential scanning calorimeter analysis with continuously heating from room temperature to 550oC at different heating rates. The hardness at all depths of the coating on the substrate could be acquired by the nanoindentation. From the DSC analysis, the onset temperature and crystallization temperature were 397.7oC and 405.5oC, respectively, at the heating rate of 10oC/min. The activation energy of the Ni-P-W coating was 307 kJ/mol analyzed by Kissinger, and Augis and Bennett methods with different heating rates. The Ni-P-W coating showed an amorphous structure in the as-deposited state and exhibited a relatively low hardness of approximately 6.8 GPa. As temperature was raised to 380oC, the hardness was slightly increased to 8.7 GPa due to the partial precipitation of Ni and Ni3P in the amorphous matrix. On heating to 500oC for 4 h, the hardness reached the maximum value of 12.3 GPa with a grain size of 33.1 nm and followed by gradual degradation above 500oC.
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