Impressive high-temperature lubrication of carbon/epoxy composites endowed by the microscopic dimensionality of carbon fillers

Epoxy resin (EP) as a friction material suffers from serious friction and wear in high temperatures. Adding various carbon fillers into EP to form carbon/EP composites is one of the solutions to this concern. However, the correlation between the filler's dimensionality and their friction properties under high temperature conditions is missing. Herein we construct a comparable dimensional model system of carbon fillers (i.e., one- to three-dimensional carbon nanocage assemblies) to reveal the dimensional effect in high temperature lubrication. Compared with EP, a merely 0.10 wt% of one-dimensional filler can reduce the composite's friction coefficient and wear rate by 36% and 95% at 30 °C, respectively; while for those filled with other dimensionalities, the corresponding decreases are less than 24% and 60%. Even at very close to EP's glass transition temperature of 150 °C, it still maintains a low friction coefficient only with a slight increase in wear. The enhanced high temperature lubrication performance is first attributed to the advantage of one-dimensional fillers to suppress the EP matrix's creep and then easily sliding in the softened transfer film. This study provides a new view for the design of carbon fillers used in EP-based high temperature lubrication composites. [Display omitted] •A comparable dimensional model system for carbon fillers is fist constructed.•The dimensional effect of carbon fillers in EP is demonstrated and explained.•EP filled one-dimensional filler has the best high-temperature lubrication property.•Optimized carbon/EP has a maximum friction application temperature of 150 °C.•The possible high temperature friction mechanism of carbon/EP is revealed.