Enhancement of adhesion strength between two AISI 316 L stainless steel plates through atmospheric pressure plasma treatment

The adhesion between AISI 316 L stainless steel plates was studied using a poly(pyromellitic dianhydride-co-4,4′-oxydianiline), amic acid as adhesive. The surfaces of two 316 L stainless steel plates were pre-treated using an atmospheric pressure plasma to improve the surface properties before adhesion tests. The surface free energies of the stainless steel plates were improved with plasma treatment and the optimum plasma treatment conditions such as plasma treatment time, plasma treatment power, gas flow rate, gap distance between power source and substrates and aging time after plasma treatment were investigated. When the mixed gas (Ar and O2) plasma was used, the surface free energy of the stainless steel was more enhanced. The surface compositions of the stainless steel were examined by X-ray Photoelectron Spectroscopy (XPS) after plasma treatment and it was proved that new oxygen-containing groups were generated after plasma treatment. Finally, tensile tests confirmed that new oxygen-containing groups formed through plasma treatment improved the adhesion strength between two stainless steel plates.