Publisher : The Materials Research Society of Korea
DOI : 10.3740/MRSK.2016.26.5.229
Title & Authors
Effects of Powder Melting Degree on Microstructural Features of Plasma Sprayed Y2O3 Coating Kang, Sang-Woon; Baik, Kyeong-Ho;
In this study, the degree of particle melting in plasma spraying and its effects on coating characteristics have been investigated in terms of microstructural features, microhardness and scratch resistance. Plasma sprayed coatings were formed using two different powder feeding systems: a system in which the powder is fed inside the plasma gun and a system in which the powder is fed externally. The internal powder spraying method generated a well-defined lamellae structure that was characterized by a thin porous layer at the splat boundary and microcracks within individual splats. Such micro-defects were generated by the large thermal contraction of splats from fully-molten droplets. The external powder spraying method formed a relatively dense coating with a particulate deposition mode, and the deposition of a higher fraction of partially-melted droplets led to a much reduced number of inter-splat pores and intra-splat microcracks. The microhardness and scratch resistance of the coatings were improved by external powder spraying; this result was mainly attributed to the reduced number of micro-defects.