Effect of TiBN Content on Microstructure and Properties of Cu-Ni Gradient Coatings Prepared by Laser Cladding

This study introduces a Ni15 intermediate layer to address cracks and low laser absorption in laser cladding of pure copper on 45 steel, preventing thermal stress and improving bonding strength. TiBN ceramic particles are added to enhance laser absorption and improve surface strength and wear resistance. Cu-TiBN gradient coatings with varying TiBN contents (0–8 wt.%) were fabricated on 45 steel. The study examines the coatings’ morphology, microstructure, phase composition, hardness, tribological performance, and wear mechanisms. Results show that TiBN alters the coating’s structure, refining the grains. With TiBN content over 4%, the coating mainly consists of the CuNi phase, and strengthening phases like NiTi and Cu2Ti form. Hardness increases from 66HV0.1 to 270HV0.1. The Cu-TiBN gradient coating outperforms pure copper in mechanical properties and wear resistance. The coating with 2% TiBN has the lowest friction coefficient (0.637), but higher TiBN content increases brittleness and cannot play a good role in reducing friction. The study demonstrates that TiBN boosts laser efficiency and wear resistance in copper-based coatings, offering a novel approach to laser cladding.