Microstructure and properties of plasma sprayed Al-doped YSZ coatings

Abstract

The inuence of alumina additive from 1 to 5 wt. % upon the microstructure and ionic conductivity of ZrO₂–8 mol % Y₂O₃ (YSZ) ceramics, deposited by means of plasma spray technology, was investigated. Plasma sprayed films have been analysed using scanning electron microscopy (SEM) and X-ray analysis (XRD). The microstructural examination reveals that alumina addition decreases the porosity and microcracks of plasma sprayed YSZ. Analysis of SEM micrographs shows that the amount of 5 wt. % alumina substantially improves the microstructure of plasma sprayed zirconia. The crystal structure of all plasma sprayed samples consists of cubic zirconia and α-alumina. By the data of ionic conductivity measurements, no signicant influence of annealing at 1073 K for 10 h was noticed on characteristic temperature dependences of σ for plasma sprayed YSZ. Alumina doping from 2 to 5 wt. % considerably increases the ionic conductivity of plasma sprayed zirconia. The higher values of ionic conductivity were obtained when 5 wt. % of Al₂O₃ powder was added to YSZ.
Keywords: films, microstructure-final, ionic conductivity, ZrO₂, Al₂O₃
PACS: 52.77.Bn, 68.55.J-, 68.90.+g