Effect of reinforcing phase type on current-carrying tribological behavior of aluminum matrix composites

Lightweight 6063 aluminum alloy has a certain strength and corrosion resistance, which makes it widely used in the field of current-carrying friction, but the current-carrying friction performance of 6063 aluminum alloy is difficult to meet the service requirements, so it is urgent to improve the current-carrying friction and wear performance of 6063 aluminum alloy. In this study, TiB_2p/6063Al, C_f/6063Al and SiC_w/6063Al composites with a volume fraction of 5 vol.% were prepared by combining discharge plasma sintering (SPS) and hot extrusion processes with particles (TiB_2p), fibers (C_f) and whiskers (SiC_w) as reinforcing phases, respectively. The influence of the reinforcing phase type on the current-carrying friction and wear properties of 6063Al matrix composites was studied, and the friction coefficient, wear rate, wear surface morphology and wear mechanism of the composites were analyzed in depth. The results show that TiB_2p and C_f are evenly distributed in the 6063Al matrix, while SiC_w is agglomerated in the composites. Among them, the hardness of TiB_2p/6063Al (68.38 HB) is the highest, which is about 11.55% higher than that of 6063Al matrix. C_f/6063Al composites have the highest density (99.41%) and electrical conductivity (48.4% IACS). The results of current-carrying friction and wear test show that the addition of different reinforcing phases will reduce the average friction coefficient of 6063Al matrix composites to different degrees, and have different effects on wear rate, current-carrying quality and wear morphology. Compared with the three reinforcing phases, C_f has the best performance in improving the current-carrying friction performance of 6063Al, with a significant reduction in wear rate, and a significant improvement in the stability of the current-carrying friction coefficient and the current-carrying efficiency. The friction process of C_f/6063Al composites showed a long-term stable friction and sliding stage, and the linear wear rate (3.19 × 10⁻⁵ mg/mm) was the smallest, which was 32.27% lower than that of 6063Al matrix. The current-carrying efficiency (66.61%) was the highest, which was 29.44% higher than that of 6063Al matrix. At the same time, the microscopic wear surface is relatively flat, there is less metal melt, and the wear mechanism is mainly abrasive wear and arc erosion. In addition, the good conductivity of C_f/6063Al composites may be one of the reasons for the stable current-carrying friction coefficient and high current-carrying efficiency of C_f/6063Al composites. The average friction coefficient (0.235) of SiC_w/6063Al composites is the smallest, but its linear wear rate is 11.25% higher than that of 6063Al matrix, and the current-carrying quality is also poor. The average friction coefficient and linear wear rate of TiB_2p/6063Al composites are 8.85% and 7.01% lower than those of 6063Al matrix, respectively, and their current-carrying quality is poor.