CMAS-Type Corrosion of Yttrium-Aluminum-Garnet (YAG)

Kurzfassung

Yttrium-Aluminum-Garnet (YAG, Y3Al5O12) is considered an attractive material for thermal and environmental barrier coatings for next generation gas turbine engines. Low-thermal conductivity, relatively high thermal expansion, good steam corrosion resistance, and favorable low diffusivity make YAG a promising coating material for metal components as well as ceramic-matrix composites. A key environmental thermal-chemical load in operation is recession by ingested airborne mineral dust particles, commonly referred to as CMAS corrosion. The interaction of YAG by CMAS has been reported in several studies in the past years, where some ambiguities regarding the chemical stability of YAG against were appearing. The presentation deals with a detailed study of different kinds of YAG materials (powders, plasma-sprayed coatings, single crystals) and their thermal-chemical response on CMAS-type attack, also by means of in situ experiments, and will address possible difficulties during interpretation of results.