Deposition Behavior of PS-PVD Yttria Partially Stabilized Zirconia Coatings

Abstract

As a novel processing technology, plasma spray-physical vapor deposition (PS-PVD) enables coatings to be deposited mainly from vapor phase. To explore the potential advantages of such a plasma spray-based processes, the deposition mechanisms and their dependency on process conditions should be better investigated. In this work, yttria partially stabilized zirconia thermal barrier coatings with quasi-columnar structure were fabricated by PS-PVD. The morphologies of the coatings for each set of deposition durations (from 30 ms to 100 s) and spray distances range from 800 to 1000 mm were studied. Besides, a design-of-experiment was used to investigate the non-line-of-sight capability of PS-PVD coatings, which were deposited on flat superalloy substrates that mounted on a static cylindrical graphite holder approximately 40 mm in diameter at various deposition angle (from 0° to 270°). Moreover, the residual stresses in the topcoat and thermally grown oxide scale were measured non-destructively using Raman spectroscopy and photoluminescence piezospectroscopy, respectively. The stage growth process of PS-PVD coatings was obtained by electron backscattered diffraction characterization of the crystal orientations and distributions of crystal size. The various microstructures of the coatings help to improve the understanding of the deposition mechanisms of PS-PVD coatings.