Effects of Cu-Coated SiC Content on Microstructure and Properties of Laser Cladding SiC_p/Al⁻Si Composite Coatings

SiC particles (SiC_p)-reinforced Al-Si matrix composite coatings were synthesized on 4032 aluminum alloy by laser cladding using powder mixtures of Al-20 wt.% Si alloy and electroless copper-plated SiC particles (SiC_p-Cu). The effects of SiC_p-Cu content on microstructure, phase composition, and microhardness of the SiC_p/Al-Si laser cladding layer (LCL) were investigated systematically. The results showed that the microstructure of SiC_p-Cu/Al-Si LCL was mainly composed of undissolved SiC_p, lump-like primary Si, lump-like Al₂Cu, plate-like Al₄SiC₄, and Al-Si-Cu ternary eutectic. In addition, the eutectic microstructure became finer with the increasing of SiC_p-Cu content. The average microhardness of the LCL increased with the increasing of SiC_p-Cu content. When SiC_p-Cu content was 50 wt.%, the average microhardness of the LCL reached 508 HV_0.05, which was about 3.5 times larger than that of the substrate. The LCL reinforced with a SiC_p-Cu content of 30 wt.% exhibits the best wear resistance.