CRACKS DEVELOPMENT FORMED AS A RESULT OF CYCLIC MICRO-IMPACTS ON THE SURFACE OF ANTI-WEAR COATINGS

Fatigue tests are commonly used to define the mechanical properties of materials intended for responsible components operating in various conditions. The fatigue strength of monolithic materials is most often determined during bending, tensile, compression, or torsion tests. The growing area of thin, hard coatings application forced the researchers to extend the fatigue tests to the coating-substrate systems. Since the behaviour of complex, modern materials are not subject to general rules, it is necessary to conduct investigation and analyses and generalise the results of these tests for given groups of materials. In this article, microimpact fatigue tests were performed to analyse the behaviour of single- and double-layer chromium and chromium nitride coatings. The microhardness and elastic modulus obtained by an indentation method were used to determine the influence of mechanical properties of the coatings on their fatigue wear. After the fatigue tests, the deformation of the coating/substrate system was examined, taking into account the geometry of the craters, and the forms of coating wear caused mainly by cracking were analysed.