HVOF coating and laser treatment: three-point bending tests

HVOF coating is one of the protective coatings of metallic materials. The mechanical locking is the mechanism for bonding the splats onto the substrate material surface. Thermal integration of coating to the base material through melting and re-solidification is short coming in HVOF thermal spraying process. In the present study, thermal integration of HVOF coating via laser melting is considered. Inconel 625 powders are sprayed onto mild steel samples. The mechanical properties of laser treated and untreated-coatings are examined through three-point bending tests. It is found that elastic limit of coating reduces after the laser treatment. The defect sites at coating-base material interface are the origin of the crack sites. Moreover, some locally distributed splats with high oxygen content are also act as crack initiation centers.