Hot corrosion, high temperature oxidation and thermal shock behavior of nanoagglomerated YSZ–Alumina composite coatings produced by plasma spray method

Hot corrosion, high temperature oxidation, thermal shock resistance and tensile strength of nanoagglomerated YSZ and YSZ–5, 10 and 15 wt.% Alumina composite coatings produced by plasma spraying have been studied. Findings showed that hot corrosion resistance of YSZ–5 and 10 wt.% Alumina composite coatings is higher than YSZ coating. After 21 h of corrosion test, degradation of YSZ and YSZ–15 wt.% Alumina coatings occurred at the interface of ceramic-bond coat while for YSZ–5 and 10 wt.% Alumina coatings degradation occurred as spallation of the surface layers of coatings. After corrosion test the peak intensity ratio of t-ZrO2/m-ZrO2 for YSZ–15 wt.% Alumina is higher than YSZ coating which shows better corrosion resistance of the former. Thermal shock and tensile strength test results showed a decrease in the shock resistance and tensile strength for YSZ–5 and 10 wt.% Alumina coatings. High temperature oxidation of YSZ–Alumina coatings was higher than YSZ coating which shows that diffusion of O2 through grain boundaries or defects as molecules or through vacancies in the lattice structure as ions has been limited.