Abstract
This paper deals with coating alternatives to hard chromium plating. Indeed, thermal spraying is already used in industry, but results are not always satisfactory for reasons of porosity and microstructures. In this study, atmospheric plasma spraying (APS) and in situ laser irradiation by diode laser processes were combined to modify the structural characteristics of thick NiCrBSi alloy layers. The microstructure evolution was studied and results show that in situ laser remelting induces the growth of a dendritic structure which strongly decreases the porosity of as-sprayed coatings and increases the adhesion on the substrate. Moreover, no phase transition after laser treatment is observed. At least, a mechanical investigation demonstrates that the combination between the plasma spraying and in situ melting with a diode laser can result in the improvement of mechanical properties. The hybrid process appears to be a possible alternative to hard chromium plating, in order to protect mechanical parts, because of the good mechanical behaviour of NiCrBSi layer. Moreover, the increase of the laser incident power causes an increase of the mean contact pressure, along with coatings hardness.
