Rapid laser sintering of alkaline fuel cell substrates using integrating mirror

Abstract

Nickel screens and foams are commonly used in alkaline fuel cell (AFC) as substrates to support electrodes. The methods used for fabrication of these substrates impact significantly on the viability, with the material and processing cost of nickel comprising almost one third of the total. Therefore, improvements to the manufacturing speed of substrates would increase affordability. Currently, state of the art commercial selective laser sintering systems are limited to a volumetric manufacturing speed of 1–3 mm3/s. This study describes a novel technique that multiplies the sintering speed of nickel AFC substrates. The novel technique is based on an integrating mirror, which creates a homogenized 60 mm wide and 0.3 mm long beam from a Nd:YAG laser, and a 0.8 mm thick nickel powder layer in a nitrogen environment. The influence of the nickel powder characteristics, and sintering parameters, as velocity, laser power, etc., and postsintering treatments of the samples on the mechanical properties of the substrates were studied. Based on experimental results, the sintering speed could be multiplied up to a factor of 150 compared to the standard laser sintering speed. Additionally, because structure of the substrate has a significant impact on cell performance, a case study was defined to present the performance and characteristics of the sintered substrates on AFCs. Laser sintered substrates show promise, exhibiting a small performance drop of less than 25 mV (about 7%) compared to the in-house standard.