Development mechanism and performance of Al2O3-PF composite coating on epoxy resin matrix composite surface by supersonic plasma spraying

In this study, an aluminium oxide-phenolic resin (Al 2 O 3 -PF) composite coating was deposited on the surface of an epoxy resin matrix composite by supersonic plasma spraying . The bond strength between the coating and matrix reached 25.64 MPa (with a maximum value of 28.1 MPa for a single test). In the oxy-acetylene ablation experiment, the mass ablative rate of the samples decreased from 0.058 to 0.033–0.035 g/s, indicating that the Al 2 O 3 -PF composite coating could effectively improve the ablation resistance of an epoxy resin matrix composite. Further, the study found that due to the stacking and aggregation of unmelted Al 2 O 3 particles, the ablation of PF by molten Al 2 O 3 and the polycondensation reaction between PF molecular chains , there were many pores in the coating; The continuous heat accumulation during blasting pretreatment and spraying leads to the initiation of cracks on the surface of the epoxy resin matrix and between the epoxy resin matrix and the reinforcing fibres, which reduces the structure and performance of the matrix itself; Through the bond strength test and combined with the microscopic topography analysis, it is found that the deposition main body of the Al 2 O 3 -PF composite coating is Al 2 O 3 /PF composite powder, and pure Al 2 O 3 particles form a shot peening effect, and at the same time, the powder particles with poor deposition effect are removed by high-temperature high-speed jet scouring, thereby improving the structure and performance of the composite coating; By analysing the coating before and after ablation, it is found that the protective mechanism of Al 2 O 3 -PF composite coating improving the high temperature ablation resistance of resin matrix composites is mainly due to the remelting of Al 2 O 3 to a certain extent during the ablation process and connecting into blocks maintaining the structural stability of the coating and ablation endotherm of PF, and outgassing creates a heat blocking effect. • Prepared an Al 2 O 3 -PF composite coating on the surface of resin composites by supersonic plasma spraying technology • The protective coating is directly spray-deposited on the epoxy resin surface, without using metal etc. adhesive layer • High bonding strength of ceramic-resin protective coating, up to 28MPa, much higher than the current research report • The ceramic-resin protective coating has good high temperature ablation resistance and electrical insulation properties • Revealing the deposition mechanism of ceramic-resin composite protective coatings on the surface of resin composites