Tribological properties of carbon nanotube/SiO2 combinations as water-based lubricant additives for magnesium alloy

The major objective of this work was to evaluate the tribological properties of the carbon nanotube/spherical SiO2 nanoparticles combinations as lubricant additives in deionized water. The tribological experiments were carried out on a linear reciprocating ball-on-plate tribometer at magnesium alloy/steel interfaces. The results demonstrate that dispersion of CNT/SiO2 combinations in deionized water exhibited superior tribological properties as well as the load-bearing capacity and lubrication film stability than individual CNT or SiO2 nanofluids. It especially emphasizes the outstanding tribological properties of the CNT/SiO2 combinations with a mass ratio of 0.2:0.3. The friction coefficient is decreased by 30.6% and the wear volume is decreased by 52.5%, when compared to the 0.5 wt % CNT nanofluids. The enhanced performances are most likely driven by the sliding-induced tribofilm of CNT and the possible ball bearings effect of nano-SiO2. These findings could provide new insights into the understanding and application of carbon nanomaterials-based combinations as water based lubricant additive and help to develop specific lubricants for magnesium alloy forming.