The Effectiveness of TEA CO2-laser Ablation for the Treatment of Hot Dipped Galvanized Mild Steel Prior to Adhesive Bonding

Abstract

TEA CO 2 -laser ablation has been studied to establish its effectiveness for the cleaning of hot dipped galvanised (HDG) mild steel. This laser-based process was demonstrated to be more effective than double-degreasing for the removal of organic contamination from a previously oily surface. In addition, the TEA CO 2 -laser was shown to modify both the near surface chemistry and the topography; the precise modifications being dependent upon the degree of treatment used. In bond durability trials, the changes introduced to the laser-treated HDG surface were shown to provide equivalent or better joints compared with degreased adherends. In the same durability trials, a commercially-available phosphate-based, wet chemical treatment was shown to provide bond durability significantly inferior to the TEA CO 2 -laser. In contrast, a chromate-based process gave markedly superior bond durability. Possible explanations for the bond test results have been given.