Effects of nano-TiN addition on annular-oscillating laser-clad Ti6Al4V coatings

With increasing demands for wear-resistant titanium alloy components in aerospace applications, surface engineering routes that combine ceramic reinforcement with laser-based thermal-field regulation are attracting growing attention. In this work, annular-oscillating laser cladding was employed to deposit Nano-TiN/Ti6Al4V composite coatings containing 0, 1, 6 and 12 wt.% TiN on Ti6Al4V substrates. The study focuses on how Nano-TiN addition modifies the phase constitution, microstructural evolution, microhardness and sliding wear response of the coatings. The results indicate that Nano-TiN promotes microstructural refinement and increases coating hardness, providing an important basis for improving the surface load-bearing capacity of Ti6Al4V. When the Nano-TiN addition was 1, 6 and 12 wt.%, the microhardness increased by 18.5%, 44.1% and 57.3%, respectively, relative to the TiN-free coating. However, the wear resistance showed an initial increase followed by a decline, and the coating containing 6 wt.% TiN exhibited the optimum wear resistance, with a 27.9% reduction in wear volume relative to the TiN-free coating. A suitable Nano-TiN addition improves the load-bearing capacity of the surface layer through microstructural refinement and hard-phase strengthening, whereas excessive Nano-TiN causes particle enrichment and agglomeration, promoting particle pull-out and third-body abrasive wear, and thus reduce wear resistance. These results indicate that annular-oscillating laser cladding combined with an appropriate Nano-TiN addition provides a practical route for designing wear-resistant Ti6Al4V surface coatings.