Substrate Template Effect on the Microstructure of Plasma-sprayed Ceramic Splats

The microstructure of plasma-sprayed coating dominates the mechanical, thermal and electrical property of coating. Since the coating is composed of thin lamellae, the crystalline microstructure of splat is an important parameter in terms of controlling coating properties and thus the performances to fulfill the versatile requirements of different applications. In this study, typical ceramic materials including of TiO₂, Al₂O₃ were deposited on both single crystal and multi-crystalline substrates at the deposition temperature higher the critical bonding temperature. The crystalline structure and its orientation and grain size of the splat crystallite were examined by SEM, EBSD and TEM. The relationship between crystalline structures of splats and substrate were examined. Results show that the splats with epitaxially grown columnar grains can be formed on the surface of substrates at a high deposition temperature and the microstructure of the splat is significantly influenced the substrate crystalline structure.