Substrate Texture Influence on the Dry Sliding Wear Behaviour of Co-Based Plasma Spray Coating

The mechanism in which the coatings made by thermal spraying adhere to the substrate is in most cases of a mechanical nature, thus being dependent on the morphology of the substrate surface. This paper study how the texture of the substrate influences the behavior of dry sliding wear, a behavior based on the adhesion to the substrate of the analyzed coatings. For this purpose, a Co - base powder, was chosen for atmospheric plasma spraying. For the substrate, a rectangular profile made of low-alloy steel was chosen, the surface of which was textured by mechanical abrasion, in order to obtain different degrees of roughness: sample S1 - Ra1 = 1.59 µm, sample S2 - Ra2 = 2.32 µm, sample 3 - Ra3.1 = 1.25 μm, Ra3.2 = 3.88 μm. In the case of sample 3, the texturing was done on one direction, with an elongated profile, so that the effect of the main direction of dry sliding wear on the quality of the coating could be studied. The tests were performed on an Amsler test machine, at constant load, for 1 hour. The samples were mounted in a fixed position, and the wear occurred on the basis of the rotation of the metal disc, without lubrication. It was found that the coating of sample 1 was the most affected, resulting even a partial delamination, and the best behavior was recorded in the case of sample 3.1.