The microstructure and properties of reinforced Ni-20WC coatings by the laser-cladding in-situ synthesis of xNbC

Laser cladding was used to fabricate in-situ synthesized xNbC, enhancing the Ni-20WC coating on AISI1045 steel. The study examined the effects of NbC synthesis on the microstructure, microhardness, tribological properties, and corrosion resistance of metal-matrix composite (MMC) coatings. No significant changes were observed in phase composition with increasing NbC synthesis. As x increased, structural changes included NbC particle agglomeration, roughening, FCC phase density variations, and WCp nucleation. At x = 20 wt%, the structure was optimally refined with even distribution. The nucleation of WCp gradually changed from granular grain boundary segregation to heterogeneous nucleation close to NbC. Thermodynamic calculations revealed a gradient-layered structure at the WCp-NbC interface. The microhardness peaked at 57.63 HRC with 20 wt% NbC, approximately 3.6 times the matrix hardness. The coatings exhibited abrasive, adhesive, and oxidative wear. The coating exhibits the best corrosion resistance at x = 20 wt%. The results provide a theoretical basis for high-performance MMC coatings via laser cladding.