Development of metal-bonding spray adhesives for use in aerospace repair applications

In many aerospace applications, the use of film and paste adhesive materials is not conducive to either good manufacturability or good bonding properties. To address this concern, the development of high-performance, epoxy-based, spray-adhesive resins has been undertaken from a research and development standpoint. These materials were investigated in the light of their potential repair applications, with focus on adhesive joint designs based on lap-shear performance and processibility of the adhesive. It was found that the resins investigated displayed adequate lap-shear strengths for the bond types of interest. However, some resins proved to be a considerable challenge during processing and solvent removal presented a problem for some materials. As expected, the combined use of mechanical testing and scanning electron microscopy revealed that the lap-shear strengths of the resins could be tailored with changes in their chemistry, and that these changes also affected the solvent removal process.