Effects of Cu-coated SiC content on microstructure and properties of laser cladding SiCp/Al-Si composite coatings

Abstract

SiC particles (SiCp)-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 (SiCp-Cu). The effects of SiCp-Cu content on microstructure, phase composition, and microhardness of the SiCp/Al-Si laser cladding layer (LCL) were investigated systematically. The results showed that the microstructure of SiCp-Cu/Al-Si LCL was mainly composed of undissolved SiCp, 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 SiCp-Cu content. The average microhardness of the LCL increased with the increasing of SiCp-Cu content. When SiCp-Cu content was 50 wt.%, the average microhardness of the LCL reached 508 HV0.05, which was about 3.5 times larger than that of the substrate. The LCL reinforced with a SiCp-Cu content of 30 wt.% exhibits the best wear resistance.