Comparison of NaVO3+CMAS mixture and CMAS corrosion to thermal barrier coatings

Corrosion results from calcium-magnesium-alumina-silicate (CMAS) and CMAS + NaVO3 (CN) to YSZ thermal barrier coatings (TBCs) are investigated and compared. CN had lower melting temperature (by similar to 50 degrees C) and viscosity than CMAS. At 1200 degrees C, CN was more aggressive to TBCs than CMAS due to the lower melting point. At 1250 degrees C, CMAS and CN both melted, but CN had severer penetration into TBCs due to the reduced viscosity and more CN was found in the coating bottoms. The corrosion mechanisms were discussed with reference to the melt viscosity, and CN corrosion is considered as a potential big threat to TBCs.