Wide-velocity range high-energy plasma sprayed yttria-stabilized zirconia thermal barrier coating - Part I: Splashing splat formation and micro-adhesive property

Regulation on the disked-shape splat is generally regarded as the traditional way to enhance micro-adhesive properties of the splat/substrate interface. In this paper, a conception of impact-induced splashing splat is proposed in order to improve these micro-adhesive properties. Three contrasting types of splashing splat were studied, utilizing a wide-velocity high-energy plasma spraying method. The experimental results suggested that the needle-shaped splat formed by the impingement of supersonic particles possessed a greater micro-adhesive strength on an metallic substrate, as much as twice that of its subsonic counterpart. The threshold velocity was 572 m/s for supersonic adhesion. In relation to air film formation and interlocking reconstruction, the solidification texture and micro-adhesive at the central and peripheral regions was also investigated. The formation process of splashing splat was divided into three stages: particle deformation, edge fragmentation and impingement. This results will provide guideline for tailoring the high-performance thermal barrier coatings.