A study on the characteristics of nano-particle reinforced adhesive joints at cryogenic temperature

Abstract

Fiber reinforced polymeric composite materials have been widely used in advanced engineering structures in cryogenic environment such as spacecraft, aircraft, and insulation panels of cryogenic liquid tanks because of their low thermal conductivity and low thermal expansion. Since the composite structures often require joining to other composite or metallic structures, the development of reliable joining technology, especially adhesive joining technology is important for composite structures in cryogenic environment because the joint is usually the weakest part among the components of assembled structures. In this thesis, the load capabilities of adhesive joints composed of the epoxy adhesive dispersed with nano-size particles and the composite adherend with nano-particle embedded were investigated at room and cryogenic temperatures. The dispersion state of nano-particles in the epoxy adhesive was observed using TEM (Transmission Electron Microscopy) with respect to the mixing conditions. The effect of nano particles on the mechanical properties of the adhesive was also investigated at room and cryogenic temperatures. From the experimental and FE analysis results, it was found that the nano particles improved the mechanical property of the adhesive at the room temperature, but there was no reinforcing effect at the cryogenic temperature. However, the lap shear strength was improved at both the room and cryogenic temperatures since the nano particle reinforced adhesive decreased thermal residual strain in the adhesively bonded joint, Also it was found that the reinforcement with nano-particle improved durability of the adhesively bonded joints under thermal loadings. For the investigation of the adhesion characteristics of surface-treated composite adherend with nano particles, the surface of glass/epoxy composite material was embedded with oxidized carbon black by heat treatment to enhance the adhesion strength of the glass/epoxy composite structure. A qua...