Comparative study of interfacial reaction between superalloy substrate and glass coating with and without alumina particles incorporation

Interfacial reaction between SiO2–Al2O3–ZnO–CaO based glass coating and K38G superalloy results in gaseous products of Zn and/or Na, and bubbling surface of the glassy coating. With incorporation of alumina particles, however, intact glass/alumina composite coating, which can restrict progressing of the excessive interfacial reaction, is formed on the alloy substrate. Enhanced high-temperature strength and viscosity of glass by alumina particles incorporation ensure the composite glassy coating with high stiffness and compactness which inhibits escape of Zn and/or Na gases from the interface, accounting for its suppressing effect on interfacial reaction.