Method of estimating the lifetime of thermal barrier coatings

Abstract

A method of estimating the lifetime of a thermal barrier coating (14), which is applied to the surface of a member subjected to cyclical thermal loads, especially a vane and/or blade of a gas turbine, by means of a bond coat (12) lying in between the coating and the member, leads to more accurate results with simplified calculation by determining, in a first step, the amplitude of the normal stress (Δσn) perpendicular to the interface between the bond coat (12) and the thermal barrier coating (14) during cyclical loading, and calculating, in a second step, the number Ni of cycles to failure for every normal stress amplitude (Δσn) in accordance with the formula N i ⁢ = C ⁡ ( △σ n σ 0 ) m where σ0 is a stress reference value and C(δox) and m(δox) are material parameters, which depend on the thickness (Δox) of an oxide layer (13), which is located between the thermal barrier layer (14) and the bond coat (12) and grows with the cyclical loading.

Dependencies are inferred from the claim text.