Microstructure and high-temperature wear properties of in situ TiC composite coatings by plasma transferred arc surface alloying on gray cast iron
来源期刊：International Journal of Minerals Metallurgy and Materials2015年第12期
论文作者：Hang Zhao Jian-jun Li Zhi-zhen Zheng Ai-hua Wang Qi-wen Huang Da-wen Zeng
文章页码：1273 - 1282
摘 要：In this work, an in situ synthesized TiC-reinforced metal matrix composite（MMC） coating of approximately 350–400 μm thickness was fabricated on a gray cast iron（GCI） substrate by plasma transferred arc（PTA） surface alloying of Ti–Fe alloy powder. Microhardness tests showed that the surface hardness increased approximately four-fold after the alloying treatment. The microstructure of the MMC coating was mainly composed of residual austenite, acicular martensite, and eutectic ledeburite. Scanning electron microscopy（SEM） and X-ray diffraction analyzes revealed that the in situ TiC particles, which were formed by direct reaction of Ti with carbon originally contained in the GCI, was uniformly distributed at the boundary of residual austenite in the alloying zone. Pin-on-disc high-temperature wear tests were performed on samples both with and without the MMC coating at room temperature and at elevated temperatures（473 K and 623 K）, and the wear behavior and mechanism were investigated. The results showed that, after the PTA alloying treatment, the wear resistance of the samples improved significantly. On the basis of our analysis of the composite coatings by optical microscopy, SEM with energy-dispersive X-ray spectroscopy, and microhardness measurements, we attributed this improvement of wear resistance to the transformation of the microstructure and to the presence of TiC particles.
Hang Zhao，Jian-jun Li，Zhi-zhen Zheng，Ai-hua Wang，Qi-wen Huang，Da-wen Zeng
State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science & Technology
摘 要：In this work, an in situ synthesized TiC-reinforced metal matrix composite（MMC） coating of approximately 350–400 μm thickness was fabricated on a gray cast iron（GCI） substrate by plasma transferred arc（PTA） surface alloying of Ti–Fe alloy powder. Microhardness tests showed that the surface hardness increased approximately four-fold after the alloying treatment. The microstructure of the MMC coating was mainly composed of residual austenite, acicular martensite, and eutectic ledeburite. Scanning electron microscopy（SEM） and X-ray diffraction analyzes revealed that the in situ TiC particles, which were formed by direct reaction of Ti with carbon originally contained in the GCI, was uniformly distributed at the boundary of residual austenite in the alloying zone. Pin-on-disc high-temperature wear tests were performed on samples both with and without the MMC coating at room temperature and at elevated temperatures（473 K and 623 K）, and the wear behavior and mechanism were investigated. The results showed that, after the PTA alloying treatment, the wear resistance of the samples improved significantly. On the basis of our analysis of the composite coatings by optical microscopy, SEM with energy-dispersive X-ray spectroscopy, and microhardness measurements, we attributed this improvement of wear resistance to the transformation of the microstructure and to the presence of TiC particles.
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