The influence of pyrolysing Al₂O₃ precursor on the high temperature properties of the YSZ-Al₂O₃ composite coating.

Taghi-Ramezani, Saeid; Valefi, Zia; Mirjani, Masud; Ghasemi, Reza

In this research, YSZ-Alumina top coat was deposited on the Hastelloy substrate with a NiCrAlY bond coat by Atmospheric plasma spraying process. YSZ-10 wt-% Al2O3 composite coatings with pyrolysed and un-pyrolysed Al2O3 powder were deposited. High temperature oxidation and thermal shock resistance of both coatings were investigated. Thermal shock test results showed that the lifetime of the YSZ-10 wt-% Al2O3 coating was increased by the pyrolysation of the un-pyrolysed Al2O3. The network of micro-segmented cracks produced by the pyrolysation of the un-pyrolysed Al2O3 improved the strain accommodation, introducing it as the main enhancement mechanism for TBC life extension. Using of pyrolysed alumina, resulted increased in the flattening degree of the splats, and so reduction of porosity and intra-splat cracks. This, in turn, reduced the permeability of the top coat and decreased the rate of oxide growth on the bond coat.

THERMAL barrier coatings; THERMAL shock; HIGH temperatures; COMPOSITE coating; PLASMA sprayed coatings; THERMAL resistance; PLASMA materials processing

Surface Engineering, 2021, Vol 37, Issue 8, p991

0267-0844

Academic Journal

10.1080/02670844.2020.1840692