One stone three birds: Multifunctional epoxy composites based on rice-granular nickel/iron bimetallic phyllosilicates enable excellent compression, anti-wear and lubricating properties under wet-sliding conditions

Abstract

Epoxy resin (EP) is a versatile thermoset resin extensively employed as protective coatings. However, its brittleness causes poor wear resistance and presents a significant challenge in the application under harsh environmental circumstances. The preparation of EP composites by rationally selecting functional inorganic fillers offers a promising strategy for enhancing mechanical and tribological properties. In this paper, multifunctional EP composites were successfully fabricated with varying mass fractions of rice-granular nickel/iron bimetallic phyllosilicate (NiFePS). The compressive properties, water contact angles, wet-sliding responses, and the morphological analysis of worn surfaces for EP composites were carried out and discussed in detail. Results indicate that the incorporated NiFePS scarcely alters the compressive stress-strain curves, still exhibiting the representative stages including elastic transformation, stress yielding and strain hardening throughout the entire compressive process. The compressive strength, elastic modulus and fracture energy initially increase and then decrease, attaining the maximum values of 266.3 MPa, 4.43 GPa, and 72.1 J/cm², respectively, with the addition of merely 1 % NiFePS. Furthermore, the introduction of NiFePS significantly reduces the water contact angle, transforming the surface of EP composite from hydrophobic to hydrophilic. The friction coefficient and wear rate of EP composites decrease sharply with the addition of NiFePS, achieving the lowest values of 0.136 and 1.24×10⁻⁶ mm³/Nm simultaneously at a filler concentration of 1 %, which represent reductions of 17.07 % and 70.55 %, respectively, compared to the resin matrix. Additionally, the wet-sliding responses affected by various applied loads, rotating speeds and abrasive durations are comprehensively discussed. Finally, the wear mechanism of EP composites is elucidated through in-depth examinations of the evolving morphologies and chemical compositions of the worn surfaces. This work presents a feasible three-in-one technology for developing multifunctional materials with significant potential in high-performance composites and coatings.