Lightweight Magnesium Nanocomposites with Enhanced Wear Resistance for Landing Gear Application

This study systematically evaluated the wear resilient performance of AZ61 magnesium alloy reinforced with 15 wt.% SiC and diverse amounts of multi-walled carbon nanotubes (MWCNTs) under dry sliding circumstances adopting pin-on-disc apparatus (ASTM G99). To identify the influence of factors like sliding speed (SS) (1-3 m/s), axial load (AL) (10-30 N), and MWCNT concentration (0-3 wt.%) that affect tribological performance, experiments were developed using a Central Composite Design (CCD) under Response Surface Methodology (RSM). SEM micrographs revealed a dispersion optimum near 2 wt.% MWCNT, where CNTs anchor to SiC and bridge the α-Mg matrix, while 3 wt.% shows agglomerates and micro-voids. Findings showed that wear loss (WL) and friction coefficient (CoF) was greatly amplified by increasing AL owing to localized heating and contact stresses. A compacted tribolayer was formed by increasing SS, which decreased WL but marginally raised the CoF. At low AL (10 N), SS (2.09 m/s), and 2.12 wt.% MWCNT, the wear resistance was significantly improved by improving load transfer and creating a lubricating carbon-rich coating, resulting in a decreased WL of 0.006 g. The CoF persisted within the range of 0.19 to 0.28. Agglomeration of MWCNTs caused increased WL and CoF when the MWCNT content is increased above 2 wt.%. Worn-surface microscopy at the optimum showed fine wear tracks and a continuous carbon/oxide glaze, evidencing a lubricious CNT-rich third-body film, whereas high AL/low MWCNT produced deep grooves and delamination.