Characterization of Roughened Substrate Surface on Bond Strength of Thermal Spray Deposits

Although substrates are often grit blasted prior to thermal spraying to improve coating adhesion, the relationship between surface roughness and bond strength is not well understood. This paper proposes a new method for characterizing the surface roughness of substrates on the hypothesis that mechanical friction between the coating and substrate primarily determines adhesive strength. The authors explain how they measure 3D surface profiles using a confocal scanning microscope and develop the necessary math to calculate friction forces and coefficients. They also present experimental results comparing the roughness of stainless steel and aluminum substrates with the adhesive strength of plasma-sprayed Al₂0₃ layers. Paper includes a German-language abstract.