Improvement in wear resistance of laser-clad Fe–Cr–Mo–B–C-(TiC) amorphous-nanocrystalline coating

Abstract

Fe-based amorphous-nanocrystalline coating has attracted attention for its unique wear and corrosion resistance. Particle reinforcing is the dominating approach for improvement in wear resistance. In this paper, the precursor for laser-clad coatings was Fe–Cr–Mo–B–C amorphous powder premixed with different content of TiC. The effects of TiC content on the microstructure, phase composition, hardness, composition distribution, and wear resistance of the coating were studied. The coating phases mainly consist of Fe23(C, B)6, Cr23C6, and TiC in case of the precursor composed of TiC. SEM experiments show that Mo coating is formed with TiC as the center. Compared with the TiC-free coating, adding TiC lowered the micro hardness of the coating. With the increase of TiC, the micro hardness first rises and then falls with the highest value occurs at coating #4. Coating #3 has the lowest friction coefficient and wear volume, suggesting the best wear resistance. Higher content of TiC forms aggregation, which weakens the bonding between it and the matrix and is easy to fall off in the process of friction and wear, leading to the decline of wear resistance. We also discuss the wear mechanism of the coatings integrating the morphology of the wear trace and the debris.