High-temperature corrosion of HfSiO4 environmental barrier coatings exposed to water vapor/oxygen atmosphere and molten calcium magnesium aluminosilicate

The hot corrosion behavior of plasma-sprayed HfSiO4 coatings exposed to molten calcium magnesium aluminosilicate (CMAS) and steam was investigated. No reactive crystallization was observed in the CMAS-attacked HfSiO4 coating which consist of tetragonal HfSiO4 and monoclinic HfO2. The penetration did not bring obvious volume expansion thanks to the buffering effect of the pores/microcracks. The bilayer environmental barrier coating (EBC) systems using HfSiO4 as top coat and Si as bond coat have the great resistance against steam corrosion. The coating degradation at high temperatures was associated with TGO volatilization and phase transformation as well as thermomechanical incompatibility.

Automated summary

The hot corrosion behavior of plasma-sprayed HfSiO4 coatings exposed to CMAS and steam was investigated. The coatings showed good resistance against steam corrosion and avoided significant volume expansion by the buffering effect of pores/microcracks. The coating degradation at high temperatures was associated with TGO volatilization, phase transformation, and thermomechanical incompatibility.