Influence of SiC particle size on microstructure evolution and tribological behavior of CoCrFeNiAl coatings prepared by laser cladding
Haoran Zhang, Yang Gao, Yaowei Yong, Lin Liu, Xiaoqiang Ren
Abstract
To investigate the influence of SiC particle size on the microstructure and tribological performance of high-entropy alloy (HEA) coatings, CoCrFeNiAl-based composite coatings were fabricated by laser cladding using SiC particles of three distinct size categories: nano-sized (<800 nm), fine micron-sized (5–20 μm), and coarse micron-sized (40–110 μm).The effects of SiC size on the phase composition, microstructure evolution, microhardness, and wear behavior were systematically analyzed. The results indicated that all coatings were primarily composed of face-centered cubic (FCC), disordered body-centered cubic (BCC), B2 ordered phase, silicon carbide (SiC), and Cr 7 C 3 . Increasing SiC particle size promoted the formation of the FCC phase (from 0.2% to 2%) and facilitated the ordering transition from BCC to B2. Nano-sized SiC particles led to the most significant grain refinement, reducing the average grain size to 3.8 μm. A critical particle size range was found to optimize hardness, with the fine micron-sized SiC coating achieving the highest average hardness of 639.7 HV 1.0 . Driven by the combined influence of phase composition variations and increased SiC particle size, the coating reinforced with coarse micron-sized SiC particles exhibited a reduced coefficient of friction as low as 0.307 and a wear rate of 2.75 × 10 -6 mm 3 /Nm. With increasing SiC particle size, the dominant wear mechanism shifted from adhesive to abrasive wear, facilitating the formation of a dense oxide–carbide film that served as a solid lubricating layer to reduce the friction coefficient and improve wear stability.