Fabrication effect on SLM and cast Inconel 718 properties for energy conversion

This study investigates the effect of fabrication methods on the microstructural, mechanical, and electrochemical durability of nickel alloy IN718, aiming to establish it as a cost-effective electrode material for direct seawater electrolysis using renewable energy sources. Selective laser melting (SLM) and conventional casting methods were used to fabricate IN718 alloy electrodes. Microstructural and mechanical characterization results show SLM samples have better compaction with maximum average hardness and densification of 347 (HV 0.5) and 99.2 %, respectively. This attribute is due to ultra-fast cooling rate and high-temperature gradient during sintering of 3D-printed samples in a layer-by-layer fashion. The electrochemical durability was investigated in 3.5 wt% NaCl electrolyte solution as a function of temperature (30, 50, and 80 °C). Electrochemical impedance spectroscopy (EIS) and Potentiodynamic polarization (PD) tests were conducted to evaluate electrochemical behavior. It was found that 3D printed samples have lower corrosion current density (52 μA/cm²) and dissolution rate (21.26 mpy) at higher temperatures. Protective film capacitance increases with reduced film thickness due to fine-grained and desirable microstructure. Therefore, modern technology (3D printing), compared to conventional production methods, offers advantages and has the potential to produce low-cost and efficient electrode material (nickel-based alloys) for energy conversion systems and other modern engineering applications.