增强相类型对铝基复合材料载流摩擦磨损行为的影响

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

  • 摘要: 轻质6063铝合金具有一定的强度和耐蚀性使其在载流摩擦领域中得到广泛应用,但6063铝合金的载流摩擦性能难以满足服役需求,因此,亟待提升6063铝合金的载流摩擦磨损性能。本研究以颗粒(TiB2p)、纤维(Cf)和晶须(SiCw)作为增强相,通过放电等离子烧结(SPS)和热挤压工艺相结合分别制备了增强相体积分数为5vol.%的TiB2p/6063Al、Cf/6063Al和SiCw/6063Al复合材料。重点研究了增强相类型对6063Al基复合材料载流摩擦磨损性能的影响,深入分析了复合材料的摩擦系数、磨损率、磨损表面形貌及磨损机制。结果表明,TiB2p和Cf在6063Al基体中分布较均匀,而SiCw在复合材料中存在团聚现象。其中,TiB2p/6063Al的硬度(68.38 HB)最高,较6063Al基体提升约11.55%;Cf/6063Al复合材料的致密度(99.41%)和导电率(48.4% IACS)最高。载流摩擦磨损试验结果表明,不同增强相的添加会使6063Al基复合材料的平均摩擦系数均有不同程度的降低,对磨损率、载流质量和磨损形貌均有不同的影响。对比三种增强相,Cf在提升6063Al的载流摩擦性能方面表现最为出色,磨损率大幅降低,载流摩擦系数稳定性和载流效率提高明显。Cf/6063Al复合材料的摩擦过程出现长时间的稳定摩擦滑动阶段,线磨损率(3.19 × 10−5 mg/mm)最小,较6063Al基体减少32.27%;载流效率(66.61%)最高,较6063Al基体提升29.44%;同时,其微观磨损表面较平整,存在较少的金属熔融物,磨损机制以磨粒磨损和电弧侵蚀为主。此外,Cf/6063Al复合材料良好的导电率可能是Cf/6063Al复合材料载流摩擦系数较稳定和载流效率较高的原因之一。SiCw/6063Al复合材料的平均摩擦系数(0.235)最小,但其线磨损率较6063Al基体增加11.25%,载流质量也较差。TiB2p/6063Al复合材料的平均摩擦系数和线磨损率分别较6063Al基体减小8.85%和7.01%,其载流质量较差。

     

    Abstract: 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, TiB2p/6063Al, Cf/6063Al and SiCw/6063Al composites with a volume fraction of 5 vol.% were prepared by combining discharge plasma sintering (SPS) and hot extrusion processes with particles (TiB2p), fibers (Cf) and whiskers (SiCw) 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 TiB2p and Cf are evenly distributed in the 6063Al matrix, while SiCw is agglomerated in the composites. Among them, the hardness of TiB2p/6063Al (68.38 HB) is the highest, which is about 11.55% higher than that of 6063Al matrix. Cf/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, Cf 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 Cf/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 Cf/6063Al composites may be one of the reasons for the stable current-carrying friction coefficient and high current-carrying efficiency of Cf/6063Al composites. The average friction coefficient (0.235) of SiCw/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 TiB2p/6063Al composites are 8.85% and 7.01% lower than those of 6063Al matrix, respectively, and their current-carrying quality is poor.

     

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