Study on friction behaviors and wear mechanisms of carbon fiber reinforced composites under load and hygrothermal service conditions

Metal materials used in marine engineering structures are prone to irreversible damage such as corrosion, wear and fatigue, which seriously reduces the service life and safety reserve of structures. Carbon fiber reinforced epoxy resin (CFRP) composites have a high specific strength/modulus, especially in the high load, washing, high temperature, high humidity and other hygrothermal service conditions have excellent friction and wear resistance, as engineering materials is expected to greatly improve the service life of the marine engineering structure. In this paper, the basic mechanical properties of CFRP as well as the friction behavior and wear mechanism under different applied loads, sliding rates, service temperatures and water lubrication were studied. It was found that based on the vacuum perfusion process, the failure fracture of CFRP plates showed that the fibers were tightly wrapped by resin, and there was no fiber agglomeration and fiber lamination. The friction and wear properties of CFRP were most sensitive to the load, because the tangential displacement caused large shear stress at the interface between the specimen and the grinding ball; service temperature was second; sliding rate was third. The influence of water lubrication was minimal, which because the water molecules increased the distance and eased the wear degrees. Compared with 500 g, the wear rate and scratch width of samples loaded with 2000 g increased by 155.9% and 111.0%, respectively, which was attributed to the irreversible debonding damage at the fiber/resin interface under high load conditions, leading to severe delamination wear. Compared with room temperature, the wear rate of CFRP at 100 ℃ and 120 ℃ increased by 72.5% and 109.2% respectively, which was attributed to the fact that the elevated temperature condition caused the epoxy resin matrix to change from a glassy state to a high elastic state, resulting in excessive plastic deformation of the resin, and finally obvious fatigue wear of CFRP. In addition, the effects of sliding rate and water lubrication on the friction coefficient of CFRP were not obvious (less than 20%), especially under 60 ℃ water lubrication, the friction coefficient fluctuated only 13.4%. This was because the lubrication function and heat dissipation of water molecules reduced the friction degree, and only slight abrasive wear occurred. The wear rate of CFRP at 120 mm/s increased by 77.9% compared with 60 mm/s, which was attributed to the inconsistency of surface and subsurface deformation of CFRP due to the large speed difference, resulting in adhesive wear.