Microstructures and mechanical properties of metallic NiCrBSi and composite NiCrBSi-WC layers manufactured via hybrid plasma/laser process

摘要

Thermal spraying is already used in industry to protect mechanical parts against wear and/or corrosion, but results are not always satisfactory due to porosity and microstructures. In this study, atmospheric plasma spraying (APS) and in situ laser irradiation by diode laser processes were combined to modify structural characteristics of metallic NiCrBSi and composite NiCrBSi-WC coatings. The micrbstructure evolution was studied with the chemical composition analysis by XRD and SEM coupled with EDS techniques. Instrumented nanoindentation tests were also conducted employing a Berkovich indenter. Moreover, the effect of the influence of the volume fraction of the reinforcing WC particles on the formation and mechanical performances of the layer was also investigated. Results show that in situ laser remelting induces the growth of a dendritic structure which strongly decreases the porosity of as-sprayed coatings, without solidification cracking (one of the major defects that can occur during the solidification of metallic or composite alloys) and improves the mechanical properties of the layer. Indeed, the layer properties such as hardness, elastic modulus, shear strength and wear rate are dependent on the percentage of WC particles in the mixture.