Deposition mechanisms of columnar structured La2Ce2O7 coatings via plasma spray-PVD

Recently, a columnar structured La2Ce2O7 (LC) coating was successfully produced via plasma spray-physical vapor deposition (PS-PVD) but in a relatively narrow processing window. In this paper, spray distances were adjusted in suitable regions of columnar structures based on our previous work attempting to precisely control coating microstructures. The columnar coatings were investigated to be regularly distributed along the axial (spraying) and radial directions of the plasma jet, and can be divided into three types including PVD-like, Closely-packed and Particle-concomitant, respectively. The PVD-like coatings deposited mainly from vapor phase distribute at relatively short spray and radial distances, while the Closely-packed ones distribute at long radial distances (periphery of the samples). In addition, the Particle-concomitant ones distribute at long spray distances. The related deposition mechanisms are discussed and a deposition model is built to provide an additional understanding of PS-PVD.