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, t hermal shock lifetime, and hot corrosion resistance were used to evalu ate performance of the SiO2-doped coating, while microstructure, compo sition and cross-sectional morphologies of the doped coatings were ana lyzed by transmission optical microscopy, electron microprobe analysis and scanning electron microscopy. The SiO2-doped coating was also sub jected to hot isostatic pressing (HIP) and laser remelting treatment t o evaluate the quality of the coating. Results showed that the ZrO2 co ating doped with an appropriate amount of SiO2 has liquid-sintering, t hermal stress-releasing and self-closing properties. The 3% wt. SiO2-d oped ZrO2 coating has high adhesive strength, superior thermal shock l ifetime, and good hot corrosion resistance compared to commercial undo ped coatings. Inserting a graded coating between the ceramic and the b ond coat substantially improves the performance of the 3% wt. SiO2-dop ed coating. Moreover, the 3% wt. SiO2-doped ZrO2 coating can be easily upgraded by HIP treatment or laser remelting. (C) 1998 Elsevier Scien ce S.A.