Impact testing appears as a most promising tool for gaining information on coating behavior in load-bearing applications. During dynamic impact test an indenter impacts successively the surface of the coating with constant force and frequency. The deformation of the coated specimen during impact testing is affected by the mechanical properties of both the substrate and the coating. Varying the impact load and the number of impacts, the evolution of coating surface deformation and contact fatigue failures can be observed. In the paper, the influence of dynamic impact load and number of impacts on the resulting impact crater volume and morphology is analysed, and the interpretation of the results in form of Wohler-like dependance is suggested and demonstrated on two types of HVOF sprayed Co-based alloy coatings. The low-number impact craters evolution and subsurface cracks propagation of HVOF sprayed Co-based alloy coatings is analyzed in more detail, by means of 3D optical microscopy and SEM. The results showed, that the higher ability to deform plastically increased the coatings dynamic impact fatigue lifetime. The cracks, responsible for coatings destruction, spread predominantly along the intersplat boundaries in the pile-up area.

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