Fabrication and Characterization of Porous 420 Stainless Steel Substrates Produced Using Rapid Prototyping Technology and Thermally Strengthened Using Solid State Sintering

Porous stainless steel substrates were fabricated using an ExOne rapid prototyping R2 machine for a hydrogen purification application. Substrates were sintered at 1075°C and 1100°C with sintering times from 30 to 120 minutes. The substrate properties were evaluated through a series of tests. The density increases and the porosity decreases with increased temperature and sintering time. Gas permeability is highly important to these substrates. As the sintering time and temperature are increased, the pore channels become more restricted and require higher differential pressures to increase the flow rate. Mercury porosimetry was used to further investigate the pore structure of the substrate. The compressive strength of the substrate was evaluated and found to increase as the sintering time was increased for samples sintered at 1075°C. Samples sintered at 1100°C did not respond with a definite increasing trend, this can be attributed a change in sintering mechanism. Microstructural evaluation was done to observe the material's response to the sintering conditions and the formation of sintering bridges between particles. Findings from this work are preliminary results used to further refine the sintering and testing parameters for future substrates.