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4804 |
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Effect of the splat microstructure on the quenching stress induced debonding during plasma spraying of TiO2 splat |
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Chang-Jiu Li* / Xi'an Jiaotong University, P.R. China Shu-Wei Yao / State key Laboratory for Mechanical Behaviour of Materials, School of Material Science and Engineering, Xian Jiaotong University, China Lin Chen/ State key Laboratory for Mechanical Behaviour of Materials, School of Material Science and Engineering, Xian Jiaotong University, China Guan-Jun Yang/ State key Laboratory for Mechanical Behaviour of Materials, School of Material Science and Engineering, Xian Jiaotong University, China Cheng-Xin Li/ State key Laboratory for Mechanical Behaviour of Materials, School of Material Science and Engineering, Xian Jiaotong University, China |
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Splat quenching stress significantly affects splat formation leading to cracking and evolution of residual stress during plasma spraying of ceramic coatings. In this study, in order to investigate the effect of splat quenching stress on the bonding state at the interface between splat and substrate, TiO2 splats were prepared on four polycrystalline TiO2 substrates with different grain size, and two monocrystalline TiO2 with the facets of (110) and (001) at the deposition temperature of 150 °C and 500 °C. The microstructure of TiO2 splats was characterized by EBSD. The bonding state at the splat/substrate interface was examined by SEM from the FIB-prepared cross-sections. From the results, it is found that TiO2 splat is nearly perfectly bonded with the TiO2 substrate at the deposition temperature of 150 °C, while the epitaxially grown TiO2 splat deposited on the underlying (110) TiO2 substrate at the deposition temperature 500 °C presents segmented morphology with small fragments shedding from the substrate. Moreover, the results reveal that the apparent interfacial debonding of plasma-sprayed TiO2 splat is caused by fracture near the interface resulting from high quenching stress during plasma spraying. It was found that decreasing the grain size of polycrystalline TiO2 splat is effective to prevent the debonding by reducing accumulated quenching stress |