Constructing ZnO seed layer on the carbon fibers for enhancing the erosion resistance of carbon fiber/epoxy resin composite coating

The poor adhesion strength between epoxy resin (EP) and carbon fiber (CF) is the bottleneck that greatly restricts the mechanical performances of carbon fiber reinforced polymers (CFRP) composite coatings. Preparing micro/nano particles on the surface of CF is an attractive strategy to boost the interfacial adhesion strength between CF and EP. However, the uneven and sparse distribution of micro/nano particles on the CFs surface negatively limited the interfacial compatibility between EP and CF, and alleviated the mechanical performances of CFRP composite materials. Therefore, in this work, we constructed a layer of ZnO seed on the surface of CFs via a hydrothermal method firstly, followed by the in-situ growth of ZnO nanolayers with needle-like structures, and further chemically grafting with active amino functional groups to boost the interfacial compatibility between CF and EP. Compared to the oxidized carbon fiber/EP composite coating (CFO@EP) and the in-situ growth of ZnO micro/nano structured carbon fiber composite coating (ZnO/CF@EP), the wear rate of AS-ZnO/CF@EP coating was significantly reduced by 53.28 % and 39.44 %, and the erosion mass were reduced by 19.38 % and 14.75 %, respectively. We revealed the mechanisms behind the interfacial reinforcement and improved erosion-wear resistance of the AS-ZnO/CF@EP composite coating, which was attributed to the mechanical interlocking brought by the uniformly dense ZnO nanolayers with needle-like structures and the chemical bonding brought by amination treatment in AS-ZnO/CF. This research work indicates that the synergistic effect of rough structure meshing and chemical bonding is crucial for enhancing the interfacial adhesion strength and erosion resistance of carbon enforced polymer composite coatings when being applied in the harsh marine environment.