ABSTRACT

The current work scrutinises the effect of incorporating WC and graphite (Gr) nanoparticles on the tribological characteristics of Mg-based hybrid nano-composites for different wt.% of WC and Gr. Hybrid nano-composites were synthesised using ultrasonic vibration associated with the stir casting technique. Synthesised nano-composites were characterised in detail using optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Characterisation confirms superior microstructural integrity compared to the base alloy Mg AZ31 and also confirms particle inclusion. Microhardness values of as-cast hybrid nano-composites were also observed. The addition of 1 wt.% of Gr nanoparticles enhances the microhardness of Mg-1WC and Mg-2WC nano-composites. A pin-on-disk tribotester was used to carry out the tribological tests, using various loads (10 N–40 N) and sliding speeds (0.1 m s⁻¹–0.4 m s⁻¹). Mg-WC nano-composites with 1 wt.% of nano-Gr show better results than those with 2 wt.% of nano-Gr. The coefficient of friction (COF) of Mg-2WC-1Gr is the lowest, followed by Mg-1WC-1Gr, Mg-1WC-2Gr and Mg-2WC-2Gr. Roughness values of worn surfaces were also examined. The worn surface of the Mg-2WC-1Gr sample shows minimum roughness. Worn surfaces were also examined under SEM to reveal wear mechanisms. Abrasion is the most dominant for hybrid nano-composites with 1 wt.% of Gr, while delamination is the most dominant for those with 2 wt.% of Gr.

摘要

目前的工作仔细研究了加入 WC 和石墨 (Gr) 纳米粒子对不同重量百分比的 WC 和 Gr 的镁基杂化纳米复合材料的摩擦学特性的影响。使用与搅拌铸造技术相关的超声振动合成混合纳米复合材料。使用光学显微镜 (OM)、扫描电子显微镜 (SEM) 和能量色散光谱 (EDS) 对合成的纳米复合材料进行了详细表征。与基础合金 Mg AZ31 相比，表征证实了卓越的微观结构完整性，并且还证实了颗粒夹杂物。还观察了铸态混合纳米复合材料的显微硬度值。添加 1 wt.% 的 Gr 纳米颗粒提高了 Mg-1WC 和 Mg-2WC 纳米复合材料的显微硬度。使用销盘式摩擦测试仪进行摩擦学测试，⁻¹ –0.4 毫秒⁻¹ )。含有 1 wt.% 纳米 Gr 的 Mg-WC 纳米复合材料比含有 2 wt.% 纳米 Gr 的 Mg-WC 纳米复合材料表现出更好的结果。Mg-2WC-1Gr的摩擦系数（COF）最低，其次是Mg​​-1WC-1Gr、Mg-1WC-2Gr和Mg-2WC-2Gr。还检查了磨损表面的粗糙度值。Mg-2WC-1Gr 样品的磨损表面显示出最小的粗糙度。还在 SEM 下检查磨损表面以揭示磨损机制。对于 1 wt.% Gr 的杂化纳米复合材料，磨损是最主要的，而对于 2 wt.% Gr 的杂化纳米复合材料，分层是最主要的。