The durability of adhesive/carbon–carbon composites joints in salt water

This paper researches the durability of the adhesive/carbon–carbon (C–C) composites joints in salt water with infrared spectroscopy (IR), energy dispersive X-ray spectrosopy (EDX) and shear strength test methods. In salt water, Na+ and Cl− ions can accelerate hydrolyzation of the adhesive and increase water ingress ability in the adhesive, although salt water cannot produce ionization potential between adhesive and C–C composites like adhesive/metal joints. The durability of the adhesive/C–C composites joints in salt water aging is lower than that in humidity aging by shear strength tests. EDX and IR spectra of the adhesive indicate that the salt water diffusion speed in the adhesive/C–C composites joints depend on not only temperature but also salt water aging time, i.e. time–temperature equivalence between temperature and salt water aging time. Shear strength tests also indicate that the rate of shear strength of the adhesive/C–C composites joints treated by silane coupling agent is lower than that treated by sand paper burnishing or by chemical oxidation in salt water aging.