Relationship between surface characteristics and properties of fiber-reinforced resin-based composites

Abstract

Fiber-reinforced resin-based composites (FRC) are in line with the concept of sustainable development owing to their excellent performance and have gradually replaced traditional friction materials. Notably, the wear of composites only accounts for about 15% of whole thickness when reaching their service life, so the surface characteristics are important factors affecting comprehensive properties. To make clear the relationship between surface characteristics and properties, especially under oil lubrication, the composites with different surface characteristics have been obtained by introducing constrain and free curing process during composites preparation. Results indicate that the surface porosity increases from 36.3% to 61.2% with the extension of free curing time, and the changes in surface roughness of different composites are consistent with surface porosity, showing an increasing trend. A more uniform and better-connected pore structure is conducive to enhancing the thermal conductivity of FRC. When the surface porosity is about 41.0%, the composite exhibits excellent tensile and interlaminar shear strength owning to better interface bonding. In addition, the dynamic friction coefficient (μd) gradually improved as the surface porosity increases, and the stability of μd is related to the change of surface roughness under continuous braking, the slight change of surface roughness corresponds to a more stable μd. The wear rate of composites first decreases from 0.73 × 10−8 cm3/J (Y1) to 0.50 × 10−8 cm3/J (Y2) and then increases to 1.57 × 10−8 cm3/J (Y6). When the surface porosity is 40–50%, the composite exhibits excellent wear resistance. Most importantly, this study provides solid basic knowledge of the structural design of composites, which is favorable for obtaining expected mechanical and tribological performances.