A process for removing aluminosilicate-based material (e.g., "CMAS") from a substrate
is described. The material is treated with an aqueous composition containing at
least one acid having the formula HxAF6, in which A is Si,
Ge, Ti, Zr, Al, and Ga; and x is 1-6. Treatment of the substrate is often carried
out by immersion in an aqueous bath. The process is also very effective for removing
CMAS-type material from cavities in the substrate, e.g., cooling holes in a gas
turbine component. Related compositions are also described.
