Abstract
The thermal cycle test of Al2O3 sprayed 1%Cr-0.5%Mo steel and 18%Cr-8%Ni steel was performed, and the failure type of thermally sprayed coating on both steels was compared. The results obtained are follows. (1)The thermal cycle fatigue life of thermal sprayed 1%Cr- 0.5%Mo steel was shorter than that of thermal sprayed 18%Cr-8%Ni steel. (2)In the case of thermally sprayed 18%Cr-8%Ni steel that is difficult to oxidize at high temperature, during thermal cycle, a tensile stress occurs in a sprayed coating and a compressive stress occurs in a substrate. Thus the thermal strain occurs at the interface of sprayed coating and substrate. The sprayed coating delaminates when the thermal cycles reach the limit value. (3)In the case of thermal sprayed 1%Cr-0.5%Mo steel that is easy to oxidize at high temperature, during thermally cycle, dense oxide film forms at the interface between the sprayed coating and substrate, and adhesive strength in the interface becomes low. Thus the sprayed coating delaminates under the lower thermal strain.
