Research Of Bonding Technology Between Aluminum Alloy And Fiberglass

As a joining method, bonding technology is applied widely in the aerospace products. For example, the bonding technology is applied to connect the fiberglass thermal layer and aluminum body of spacecraft. However, the adhesive need to be solidified at the high temperature in the course of forming thermal layers, and the linear expansion coefficients of aluminum and fiberglass thermal layers materials are different, great internal stress will form due to thermal expansion and contraction effects during production progress. Especially, when the aluminum body of products is sprayed with a coating, debonding phenomenon can occur between the aluminum body or the thermal layer and the coating because of the great internal stress.For investigating the adhesive between aluminum and fiberglass composites, five kinds of high temperature resistant epoxy adhesive are chose. Shear and tear properties of the adhesive joints are tested, and shear and tear properties of the joints after undergo alternating hot and cold test and heat aging test are also investigated. Through synthetically comparing the test data, the adhesive property of J-116 is best. The effects of adhesive thickness, surface treatment, the nature and thickness of base materials and fiber orientation of composite materials on the strength of the adhesive joint are analyzed. When the thickness of adhesive reaches a certain value (>0.15mm), the shear strength decreases with the thickness of adhesive increasing. However, if the thickness of adhesive is too small (<0.15mm), the strength of adhesive joints is also low. The ideal value of adhesive thickness is 0.15-0.3mm. When the adhesive surfaces of basic substrates are mechanically polished, satisfactory results can be obtained. Phosphoric acid anodizing treatment of aluminum alloys can promote the adhesion performance greatly. If the adherents are thicker, the stress concentration factor will be smaller, and which will bring about that the shear strength increases. In order to obtain greater bonding strength, the fiber direction of composite materials should be consistent with the load direction.In the actual application of products, J-116 can meet the requirement of bonding strength for the adhesive of aluminum body and FRP. But as an absorbing material coating the surfaces of aluminum body, debonding phenomenon is difficult to be avoid, because the inner strength of absorbing material is too low. Subsequent pour adhesive treatment is adopted to repair the defects.