Photothermal Investigation of Cavitation Wear Protecting NiTi-Coatings

Photothermal radiometry was applied to investigate the effect of abrasion by cavitation on steel which was supplied with a wear protecting NiTi film. Phase and amplitude data from areas on the sample which where damaged differently by the cavitation effect indicate the appearance of a three layer structure with the cavitation treatment. With cavitational impact the thermal diffusion time of the first layer decreases and an interfacial layer emerges which is identified as a surface region of the steel substrate which has undergone a stress induced transformation from an austenite to a martensite structure.