Environmental barrier coating for silicon-containing substrates and process therefor

摘要

A protective coating (20) for use on a silicon-containing substrate (12), and deposition methods therefor, The coating (20) has a strontium-aluminosilicate (SAS) composition that is less susceptible to degradation by volatilization and in corrosive environments as a result of having at least an outer surface region (22) that consists essentially of one or more stoichiometric crystalline phases of SAS and is substantially free of a nonstoichiometric second crystalline phase of SAS that contains a substoichiometric amount of silica. The coating (20) can be produced by carrying out deposition and heat treatment steps that result in the entire coating (20) or just the outer surface region (22) of the coating (20) consisting essentially of the stoichiometric celsian phase.