Modification of ceramic surfaces by excimer laser for adhesive bonding

Two engineering ceramics, LT35 (TiC+AI₂O₃) and Si₃N₄ were surface-treated using a 800 mJ KrF excimer laser. The effect of pulse frequency, energy density and number of pulses upon the surface morphologies and roughness were examined. Conical structures were observed after the laser treatment. The ablation depth measured by the height of cones were found to be dependent upon the type of ceramics and laser parameters. The sizes of the lava cones were related to the laser energy intensity at fixed pulse frequency and specimen traverse speed. The ablation effect are explained in terms of various thermodynamics constants. The treated surfaces were adhesion bonded using a toughened epoxy resin adhesiv. Shear tests were carried out. The increase in adhesion shear strength of the treated surfaces were largely dependent upon the laser parameters. Significant improvement in adhesion shear strength of the laser treated surfaces were achieved as compared with those surfaces in the as-received, SiC paper abraded and sand blasting conditions.