Effects of imposed displacement and initial coating thickness on fretting behaviour of a thermally sprayed coating

This paper describes the effects of imposed displacement and initial coating thickness on fretting wear behaviour of a thermally sprayed coating. Initial coating thickness and imposed displacement between two mating components are important parameters affecting durability of a thermally sprayed coating under fretting conditions. Nevertheless, the effects of imposed displacement and coating thickness at flat-and-rounded frictional contacts of aerospace dovetail connections are not sufficiently investigated. In this paper, fretting wear experiments with a double-layer thermally sprayed coating are performed under different displacement and coating thickness conditions. The effects of the parameters are then identified by directly comparing the ratio of maximum tangential force to normal force. Experimental results show that the ratio evolutions are similar on the ratio versus accumulated reciprocal sliding distance chart within the displacement range of 0.4–0.6 mm. In addition, it is demonstrated that durability of the coating is increased with increasing the initial thickness of the coating. Finally, the effect of the initial coating thickness is described with exponential evolution law of fretting damage.

► Durability of a thermally sprayed coating decreases with increasing imposed displacement magnitude in terms of number of cycles.
► Friction coefficient evolutions of a thermally sprayed coating are similar within chosen displacement range on friction coefficient versus accumulated sliding distance chart.
► The increase of the initial coating thickness leads to the increase of durability of a thermally sprayed coating.
► The effect of initial coating thickness on a thermally sprayed coating is described with exponential evolution law of fretting damage.