ADHESIVE BONDING OF CLEAN AND OIL-CONTAMINATED ELECTROGALVANIZED STEEL SUBSTRATES

The performance of two-part, amidoamine-cured epoxy adhesives on clean and oil-contaminated electrogalvanized steel(EGS) was studied using s creening and lap shear tests. On exposure to boiling water, the cured epoxy adhesives with amidoamines having higher amine value delaminated from the clean and oil-contaminated EGS surfaces before those cured w ith amidoamines having low amine value. The results of X-ray photoelec tron spectroscopy (XPS) showed that the adhesives cured with amidoamin es having high amine value were unable to displace the oil from the EG S substrate. However, the durability and the strength of the adhesive bonds on the oiled EGS could be improved by adding proper amounts of s ilane or wetting agent to the adhesive. The preferential adsorption of amino curing agents occurred on the clean EGS surface, confirmed by X PS and reflection absorption infrared spectroscopy, and this decreased the durability of the bonds in boiling water. In addition, from XPS a nalyses of various specimens, different amounts of cured resins were d etected in the adhesive/EGS interfacial regions which affecting the du rability of the adhesive bonds. In addition, the amidoamine curing age nts may form complexes on the EGS surface.