Influence of laser texturing pre-treatment on HVOF-sprayed WC-10Co-4Cr+GNP coatings on AISI 304

Abstract

Abstract High-Velocity Oxygen Fuel (HVOF) is one of the most important thermal spraying techniques for protective coating on pristine alloy surfaces by cermet feedstock powders. In the article, grit blasting before HVOF coating is replaced by laser texturing to create specific roughness and deterministic cavities pattern for better mechanical interlocking of deposited WC-10Co-4Cr + 3% Graphene Nanoplatelets (GNPs) on AISI 304 Steel Substrate. Two geometries; first one is Circular texturing (CT) of diameter (d) 100 μm and pitch (p) 120 μm, second is triangular texturing (TT) of side (s) 100 μm and side to side (ss) distance 120 μm have been used. Various testing measures; like surface roughness, XRD analysis, FESEM image analysis, EDS analysis, lattice strain and residual stress, scratch test, Vickers hardness test on coating and base substrate cross-section, and pin-on-disc test for sliding wear behaviour have been performed. After these coating characterizations, it was found that the lattice strain and residual stress decreases significantly, the micro-hardness of the cross-section improved, the adhesion strength of the coating was enhanced and a low sliding wear rate on the coated surface was observed. Uniform distribution of feedstock powder on the surface but higher porosity on the TT surface showed by FESEM image analysis and a large number of cracks observed during scratch tests at higher load.