Wetting-based assessment method of laser-engineered microstructures to enhance interface bonding in titanium bipolar plates

• Innovative method is proposed to evaluate wetting performance of laser surface microstructures. • Influences of adhesive strip width and vacancy time on wetting distance are discussed. • Laser surface modification maximally increases the shear bonding strength by 137%. • A 3-order function with goodness-of-fit of 0.9407 is established to evaluate bonding strength. Interface bonding technology is extensively utilized for sealing and joining in diverse engineering applications, and laser surface modification has effectively emerged to enhance the bonding interface through microstructure reconstruction. However, interfacial bonding performance varies significantly with laser-regulated microstructures, and it lacks of rapid evaluation method to guide the optimization strategy of laser-regulated microstructures. Herein, we pioneers a rapid evaluation method to correlate the interfacial bonding strength with measurable wetting distances, aiming to accelerate the iterative optimization of laser-regulated microstructures. This study focuses on the application scenario of titanium bipolar plates in hydrogen fuel cells, and three typical microstructures (dimple, groove and grid) are fabricated by nanosecond pulsed laser on titanium surfaces to strengthen the bonding interface. A novel method is proposed to evaluate the interfacial bonding strength for three laser-regulated microstructures, employing a simple and easily measurable wetting distance of adhesive strip on laser-treated titanium surface as the key parameter. By systematically excluding the influences of adhesive strip width and vacancy time, stable wetting distances are measured for laser-processed titanium surfaces with different microstructures. Experimental results reveal that groove microstructures exhibit the most stable wetting distance, while the highest wetting distance is observed for grid microstructures. Furthermore, a 3-order polynomial function with goodness-of-fit of 0.9407 is established to model the correlation between wetting distance and interfacial bonding strength, enabling the rapid assessment of interfacial bonding strength for laser-regulated microstructures. Our study advances the development of evaluation method for interfacial bonding strength, and deepens the understanding on the important role of wetting performance in interfacial bonding strength.