FURTHER-STUDIES INTO THE EFFECTIVENESS OF CO2-LASER TREATMENT OF METALS FOR ADHESIVE BONDING

The effect of CO2-laser treatment on the wettability of mild steel is presented. In addition, data are presented on the initial joint streng ths and durability of joints formed between a single-part epoxide and both mild steel and aluminium. A large increase in stressed durability performance was observed with the laser-treated aluminium compared wi th degreased-only controls. The laser treatment was shown to efficient ly remove the organic contamination from the metallic substrates. Auge r analysis showed that the laser interacts more with the mild steel th an the aluminium adherends, to produce a relatively thick surface oxid e. The changes to the mild steel surface introduced by the CO2-laser t reatment facilitate an approximately 50% increase in initial joint str engths. The absolute strength retention in unstressed durability trial s was greater with the laser-treated adherends than with degreased-onl y controls. (C) 1997 Elsevier Science Ltd.