Fabrication of Fe-based composite coatings reinforced by TiC particles and its microstructure and wear resistance of 40Cr gear steel by low energy pulsed laser cladding

Wear resistant property is the key factor that determines the lifetime of gears. The coating of titanium carbide (TiC) composite on the surface of gears is an effective way to improve their lifetime. In this paper, two coating fabrication methods, the direct cladding of TiC coating and the in-situ synthetic of TiCx coating under low laser energy pulsed, were prepared on the 40Cr gear steel surface. Direct cladding TiC refers to the preparation of coatings by laser cladding TiC particles. In-situ synthesis of TiC used laser to provide energy, which promoted the reaction of Ti powder and graphite to form TiC. The microstructure, and the phase composition of coating materials were characterized by scanning electronic microscopy (SEM) and X-ray diffraction (XRD). Moreover, the micro-hardness and wear resistance of different coatings were tested. The results show that the coatings with a large amount of TiC particles can be prepared at low energy pulsed, which can significantly improve the micro-hardness and wear resistance of the coating. However, low pulsed energy can only promote the formation of a small amount of TiC in Ti powder and graphite, and the micro-hardness and wear resistance were not significantly improved. The study suggested that direct laser cladding of the 50 wt% TiC coating has the best wear properties of the TiC coatings by low energy pulsed.