Spray parameters play an important role on the microstructure and properties of plasma sprayed coatings. Parameters such as spray distance, plasma gas flow and current, raster speed and spray angle all can be varied. In this paper, an integrated study to investigate the effects and influences of spray angle on properties of yttria-stabilized zirconia coatings was carried out with spray angles of 60°, 75° and 90° (to the substrate surface). In situ coating property sensor (ICP) based on beam curvature measurements was used to measure the evolving stress and elastic moduli of the resultant coatings and combined with other characterization tools for thermophysical property and microstructure analysis, such as laser flash and scanning electron microscopy (SEM). The results indicate that the coating with 60° spray angle had the lowest thermal conductivity and more compliant structure. This study seeks to understand the mechanism for this effect and will provide important insight into parametric sensitivities on complex spray parts.

Formation of bonelike apatite is an essential prerequisite for implants to make direct bond to living bone. The apatite formation can be assessed in vitro using a simulated body fluid (SBF) that has almost equal compositions of inorganic ions to human blood plasma. In this study, Ti coatings were prepared by vacuum plasma spraying, and then they were treated by NaOH aqueous solution, immersed in distilled water, heated at 600 °C in a furnace. Microstructure and bioactivity of the surface modified Ti coatings were examined by SEM observation and SBF test respectively. The results obtained revealed that a net-like structure comprising of many micropores was present on the surfaces of the treated Ti coatings. After immersed in SBF, apatite layer was formed on their surfaces, suggesting that the surface modification coatings have good bioactivity.