An experimental study on the mechanical performance of BFRP-Al adhesive joints subjected to salt solutions at elevated temperature

In order to study the mechanical properties of basalt fiber reinforced resin polymers–aluminum alloy (BFRP-Al) single lap joints (SLJ) under different humid and hot conditions. 80 °C/deionized water (DI-water), 80 °C/3.5%NaCl solution and 80 °C/5%NaCl solution were used as the aging conditions of BFRP-Al joints. Through the hygroscopic experiment, the maximum water absorption rate of dumbbell-shaped adhesive in the three environments was 7.15%, 4.12% and 4.96%, respectively. The maximum water absorption of basalt fiber reinforced resin polymers (BFRP) in the three environments was 2.24%, 1.2% and 1.55%, respectively. It is concluded that salt solution inhibits the absorption of water by adhesive and BFRP. The quasi-static tensile test of the joint was carried out. And the result shows that the failure strength of the joint in the three environments increases at first and then decreases with the prolongation of aging time. And the failure strength of the joint in the high-temperature salt solution is better than that in high-temperature DI-water. DSC experiments show that changes in glass transition temperature (Tg) reflect changes in failure strength. SEM image analysis of the joint failure mechanism can show that the resin matrix damage in BFRP increases with aging time. The mechanical properties of the joint at the later stage of aging depend on the performance of BFRP.