Assessment of Tribological Properties of Ti₃C₂ as a Water-Based Lubricant Additive

Water-based lubrication has attracted remarkable interest due to its environmental and economic advantages. However, practical applications of water-based lubrication are often limited, mainly because of low viscosity and corrosivity. The use of additives has been proposed to overcome these limitations. In this work, the tribological characteristics of titanium carbide (Ti₃C₂) MXenes, as additives for water-based lubrication, were systematically investigated for contact sliding between stainless steel under various normal forces and Ti₃C₂ concentrations. Both friction and wear were found to decrease with increasing Ti₃C₂ concentration up to 5 wt%, and then increased when the concentration was larger than 5 wt%. The results suggest that Ti₃C₂ flakes hindered direct contact, particularly at the edges of the contact interfaces. It was further shown that the agglomeration of Ti₃C₂ flakes may have reduced the hindering when an excessive amount of Ti₃C₂ (e.g., 7 wt%) was applied. The decreases in the friction coefficient and wear rate with 5 wt% of Ti₃C₂ concentration w approximately 20% and 48%, respectively. The outcomes of this work may be helpful in gaining a better understanding of the tribological properties of Ti₃C₂ as a feasible water-based lubrication additive.