Laser cladding of heterogeneous structured Cu-Cr-W-SiC coatings with balanced electrical conductivity and wear resistance

Abstract

• A heterogeneous structure of soft Cu-rich zones and hard Cr-rich regions was constructed. • Synergistic enhancement of electrical conductivity and wear resistance was achieved. • Thermodynamic mechanisms of SiC decomposition and core–shell structures formation were elucidated. • A design concept of “soft layers for conduction and hard layers for wear resistance” was proposed. Although copper alloys exhibit high electrical conductivity, their inherent low hardness and insufficient wear resistance significantly limit their application in high-energy current-carrying friction scenarios. This study leverages the liquid–liquid phase separation (LLPS) characteristics of immiscible alloys during non-equilibrium solidification and employs laser cladding technology to fabricate Cu-36Cr-xW-4SiC (x = 0, 2, 5, 10 wt%) composite coatings on CuCrZr alloy. The research systematically investigated the influence of tungsten content on the heterogeneous microstructure and the regulation of electrical conductivity-wear properties of the coatings. The results indicate that the introduction of 2 wt% W suppresses the Stokes migration effect of the second phase in the molten pool, promoting the periodic layered distribution of Cr-rich hard phase regions along the edges of the molten pool. This forms a hardness gradient up to 12 times higher than the Cu-rich soft phase regions. This heterogeneous structure achieves decoupled optimization of conductivity (35.8 % IACS) and wear resistance (average volumetric wear rate of 0.158 mm 3 /km, an 88.5 % reduction compared to the substrate) through a synergistic mechanism of “hard phase bearing wear load − soft phase maintaining conductive pathways”. The design strategy proposed in this study provides a new paradigm for the development of high-performance copper-based coatings.

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