Plasma Sprayed Raney Nickel Coatings for Hydrogen Production by Alkaline Water Electrolysis

Plasma sprayed coatings of Raney nickel alloys developed as electrodes for hydrogen evolution electrodes in alkaline media, exhibit poor resistance to electrochemical erosion. The aim of this work is to develop an understanding of the correlation between plasma spray process parameters and coating quality and with that improve the electrochemical performance of the coatings. Air plasma spraying with TriplexPro gun was performed using NiAlMo powders. Plasma parameters were varied and particle inflight velocity and temperature was measured by Accuraspray. Coatings were developed for conditions in which particles in-flight temperatures were comparable but in-flight velocities differed. Electrochemical tests were performed for evaluating the effect of different velocities on electrode performance. Coating attained with particles having higher velocity exhibited better electrochemical performance and durability. The microstructure and elements map before and after the electrochemical test performed by SEM and EDX show that the coatings with higher velocity particles led to microstructure that enabled better activation of the electrodes and higher surface area for reactions.