Laser Surface Modification on Titanium Bipolar Plate of Hydrogen Fuel Cell to Enhance Bonding Performance

Adhesive bonding plays an increasingly important role in joining metallic bipolar plates of hydrogen fuel cell due to high manufacturing efficiency and small deformation with comparison to other joining technologies (e.g. laser welding, sealing gasket), however, tremendous difference in surface physiochemical properties results in poor bonding compatibility between metallic polar plate and adhesive, which remains a challenge to the wide application of adhesive bonding technology. In this study, titanium bipolar plate with excellent corrosion resistance and high specific strength was laser-treated to modify its surface physiochemical properties for the improvement of interfacial bonding compatibility. Results indicate that laser surface modification enable a maximum improvement of ~130% on bonding strength of titanium bipolar plate with comparison to untreated condition. In addition, the effects of laser processing parameters (e.g. overlap ratio, laser power, aspect ratio) on bonding strength were investigated through orthogonal experiments. It is found that overlap ratio exhibits a more significant effect on bonding strength than laser power, and the weakest effect was observed for aspect ratio. On the premise of ensuring the improvement of bonding strength, we further optimized processing parameters of laser power and overlap ratio to decrease laser input energy to avoid large thermal deformation of titanium bipolar plate, since laser input energy was determined by pulse energy and energy density, corresponding to laser power and overlap ratio, respectively. At the end of this work, laser processing parameters were optimized for adhesive bonding of titanium bipolar plate.