Dual-phase enhanced polytetrafluoroethylene composites with friction-trigged self-healing interfaces: Role of antigorite and graphene in tribofilm evolution

The incorporation of self-healing compositions or structures into polymers is a highly effective strategy to improve their tribological performance. In this study, mono antigorite (Atg)-reinforced and Atg + graphene (GNs) dual-phase-reinforced polytetrafluoroethylene (PTFE) matrix composites were fabricated via a combination of ball-milling, cold-press molding and sintering techniques. A systematic study was conducted on the phase composition, microstructure, mechanical properties, and tribological behaviors of composite materials. The results demonstrate that, compared to neat PTFE, the composites exhibit an 18.7–23.7 % enhancement in the Shore hardness, an 8.0–83.8 % improvement in the compressive strength, a 2.4–20.9 % reduction in the friction coefficient, and a 41.2–56.3 % decline in the wear rate. The introduction of Atg induced a friction-triggered self-healing effect on the worn surface and interface. For the Atg/PTFE composites, a tribofilm composed primarily of Mg₂SiO₄, SiO₂, graphite, metal oxides, and SiC was formed on the worn surfaces. In (Atg + GNs)/PTFE composites, the addition of graphene promotes a secondary dehydration reaction of antigorite, resulting in an increase in the tribochemical reaction products (TRPs) within the tribofilm. Furthermore, graphene facilitated the formation of perfluorocarboxylic acid groups, which significantly enhanced the adhesion and stability of TRPs. This novel synergistic mechanism results in the formation of a more dense, compact, and coherent friction film on the corresponding steel surface, primarily composed of MgSiO₃, graphite, and FeO. This addresses the issue of severe wear in traditional reinforced PTFE-based composite materials under extreme conditions, providing new insights into the design of friction-triggered self-healing polymer composites for extreme conditions.