Improvements of the interfacial adhesion between water-based coating and carbon fiber reinforced polymer composite by deposition of silica particles

Carbon fiber reinforced polymer matrix (CFRP) composites often require organic coatings for decorative and protective purposes. Due to the smoothness and low polarity, the surface must be polished to make the coating have sufficient adhesion strength. However, sanding process damages the strength of composites and causes dust pollution. In this work, in order to enhance the interfacial adhesion between water-based coating and CFRP composite, SiO2 particles were produced on the composite surface through in-situ heterogeneous deposition by sol-gel method. The effects of this treatment process on the surface morphology, roughness, chemical composition, wettability and coating adhesion strength of CFRP composites were studied, and the adhesion strength was compared with that of traditional sandpaper sanding and acidification process. The results showed that the adhesion strength of the water-based coating increased to 5.72 +/- 0.34 MPa on the surface of the CFRP composite panel modified by the heterogeneous deposition of SiO2, when the ammonia content was 0.20 mol L-1, which was 133.47% higher than that of the original sample. The deposition of SiO2 particles by sol-gel method can significantly improve the surface energy and surface roughness of CFRP materials.The heterogeneous deposition of SiO2 on the surface of CFRP can effectively enhance the adhesion strength of the coating without causing dust pollution and damage to the composite matrix.The adhesion strength of the water-based coating is increased to 5.72 +/- 0.34 MPa on the modified surface of the CFRP composite panel, which was 133.47% higher than that of the original sample.