Investigation on growth mechanisms of columnar structured YSZ coatings in Plasma Spray-Physical Vapor Deposition (PS-PVD). Issue 10 (August 2019)

• Record Type: Journal Article
• Authors: He, Wenting; Mauer, Georg; Sohn, Yoo Jung; Schwedt, Alexander; Guillon, Olivier; Vaßen, Robert
• Is Part Of: Journal of the European Ceramic Society. Volume 39:Issue 10(2019)
• Page Start: 3129
• Page End: 3138
• Publication Date: 2019-08
• Subjects: PS-PVD -- YSZ TBCs -- Equiaxed growth -- Preferential growth -- Columnar microstructure; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2019.04.003
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: By Plasma Spray-Physical Vapor Deposition (PS-PVD), major fractions of the powder feedstock can be evaporated so that the coating builds up mainly from vapor phase. In this work, the deposition mechanisms at different PS-PVD conditions were investigated. Depending on the plasma flow conditions and the substrate temperature, the columns in the coatings possess successively pyramidal, cauliflower, and lamellar shaped tops. In addition, the different microstructures show characteristic crystallographic textures, in which different in-plane and out-of-plane orientations were observed by pole figures. Based on investigations by electron back-scatter diffraction (EBSD), the overall coating growth process can be roughly divided into three subsequent stages: equiaxed growth, competitive growth, and preferential growth. Influences of diffusion and shadowing on final coating microstructure and orientation were discussed. The formation of equiaxed grains was proposed to be caused by high nucleation rates, which are probably induced by large undercooling and super-saturation at the beginning of deposition. The preferential growth orientation was preliminarily explained based on an evolutionary selection mechanism.