Effect of Scanning Speed on the Microstructure and Properties of Co-Cu-Ti Coatings by Laser Cladding

Co-Cu-Ti composite coatings were fabricated on Ti6Al4V substrates by laser cladding. The Criteria Importance Through Intercriteria Correlation–Technique for Order Preference by Similarity to Ideal Solution methodology was employed to determine the optimal parameters. The effect of varying the scanning speed, a critical parameter, was investigated to evaluate its influence on the coating’s microstructure and performance. The phase composition of the coatings comprises Co-Ti phases and Cu-Ti phases. The microhardness and wear resistance of the coatings initially increase as the scanning speed rises, reaching a peak before subsequently declining. The predominant wear mechanisms of the coatings are abrasive wear, with minor contributions from adhesive wear and fatigue wear. The wear resistance of the coating is superior to that of the TC4 substrate, primarily due to the synergistic enhancement from the strengthening effect of the Co-Ti phase and the lubricating effect of the Cu-Ti phase. The composite coatings fabricated at a scanning speed of 3 mm/s exhibited superior properties. Specifically, the microhardness measures 788 HV0.2, the coefficient of friction is approximately 0.57, and the wear cross-sectional area is 3.57 × 10−9 mm2. At this speed, these two effects achieve an optimal balance, making it the best process parameter for wear resistance.