Surface treatment of titanium for adhesive bonding to polymer composites: a review

At present, the bonding of polymer composites to titanium is a problem, which has not been fully resolved. Previous research has shown that bond strengths can be significantly improved by surface treating the adherends prior to bonding. However many of the successful surface treatments involve the use of hazardous chemicals, which have to be phased out as part of an EU directive, which paves the way for less toxic environmentally friendly methods. In this paper various methods of surface treatment including traditional treatments such as acid etch, anodisation, novel plasma spray and laser treatments for both polymer composites and titanium will be discussed. These treatments will be reviewed with respect to changes in surface tension, surface roughness, surface chemistry and how these changes affect bond strength and durability of polymer composite titanium adhesive joints.