The variability in strength of thermally sprayed coatings

Abstract

There is a large variability in the bond strengths of coatings which are determined by the tensile adhesion test method. The primary intention of this work is to establish a suitable parameter which measures the strength variability of thermally sprayed coatings, as well as a meaningful parameter to index that strength. The Weibull modulus for metal ( e.g. mild steel) and ceramic ( e.g. zirconia, alumina) coatings has been found and then related to the defect nature of the coating. This work has shown that the Weibull analysis method is a pertinent parameter to examine in the case of thermally sprayed coatings. The testing methods allow an “index of integrity” to be established for thermally sprayed coatings, involving both the Weibull modulus m and the characteristic value σ 0 so that interlaboratory tests or products from different manufacturers can be compared and contrasted.