Plasma-sprayed ZrO2 thermal barrier coatings doped with an appropriate amount of SiO2

A plasma-sprayed 8% wt. Y2O3 partially stabilized ZrO2 thermal barrier coating was doped with a certain amount of SiO2. Adhesive strength, thermal shock lifetime, and hot corrosion resistance were used to evaluate performance of the SiO2-doped coating, while microstructure, composition and cross-sectional morphologies of the doped coatings were analyzed by transmission optical microscopy, electron microprobe analysis and scanning electron microscopy. The SiO2-doped coating was also subjected to hot isostatic pressing (HIP) and laser remelting treatment to evaluate the quality of the coating. Results showed that the ZrO2 coating doped with an appropriate amount of SiO2 has liquid-sintering, thermal stress-releasing and self-closing properties. The 3% wt. SiO2-doped ZrO2 coating has high adhesive strength, superior thermal shock lifetime, and good hot corrosion resistance compared to commercial undoped coatings. Inserting a graded coating between the ceramic and the bond coat substantially improves the performance of the 3% wt. SiO2-doped coating. Moreover, the 3% wt. SiO2-doped ZrO2 coating can be easily upgraded by HIP treatment or laser remelting. (C) 1998 Elsevier Science S.A.