A study on laser interaction characteristics with carbon-nanotube composite bipolar plate used in fuel cells

Due to the increasing applicability of Carbon Nanotubes (CNTs) in various technological fields, processing of CNT composites to the desired size and shape is a critical issue. In this regard, pulsed lasers offer a wide range of applications. However, laser processing of CNT composites is limited to micro-scale applications. This paper aims to make a clear understanding of laser interaction with CNT composite plate, experimentally, using a pulsed nanosecond laser, as a step towards creating laser-structured micro-channels on a CNT composite bipolar plate for PEM fuel cell. Penetration depth, top width, spatter distribution, and overall morphological observations on the behavior of ablated regions are considered response variables. SEM and 3D Scanning Confocal Microscope were used for physical observations. According to the results, the effect of the number of passes is the highest on controlling penetration depth and top width. Power and scanning speeds result in a relatively smooth operation without major effects on the physical morphology and offer effective operation for low to medium control of penetration depth and top width. Pulse repetition rate presents a unique nature of interaction that resulted in a critical repetition rate distinguishing three different regimes each with certain distinct thermal behaviors. Overall, results suggest that laser processing can be considered as a potential method for manufacturing flow channels of bipolar plates using CNT composite materials.