Enhancement of adhesive joint strength by laser surface modification

This report describes modification of titanium surfaces by means of a laser ablation process that generates microcolumnar arrays (MCA) and thereby increases the adhesive bond strength between titanium plates in many ways. Bond strength improves due to (i) increase in surface area, (ii) mechanical locking of adhesive between microcolumns, and (iii) modifications in the surface chemistry of the adherend and consequent improvement in wettability of adherend/adhesive interface. Due to the enhancement in bond strength, failure of joints moves away from interfaces into the bulk of the adhesive layer, suggesting that the strength-limiting factor is the epoxy strength.