Experimental and Numerical Study of the Effect of Gas-Shrouded Plasma Spraying on Cathode Coating of Alkaline Electrolysis Cells

Kurzfassung

The aim of this work is to improve the performance of electrodes prepared via atmospheric plasma spray by means of gas shrouding which is expected to apparently reduce the oxygen content of the plasma plume and subsequently improve the coating quality. Electrodes with dual-layer coating for alkaline water electrolysis were deposited on Ni-coated perforated substrates. Microstructure and morphology were studied by SEM. Element content was measured by EDS. Enthalpy probe was employed for measuring plasma temperature and velocity as well as the gas composition. For verifying and better understanding the shrouding effect numerical calculation was carried out according to the experimental settings. Electrochemical test was carried out to validate the shrouding effect. The results showed slight protecting effect of gas shrouding on plasma plume and the final coating. Overall the dual-layer region, the measured oxygen fraction was 3.46% and 3.15% for the case without gas shrouding and with gas shrouding respectively. With gas shrouding the coating exhibited similar element contents as the coating sprayed by VPS while no obvious improvement was observed in the microstructure or the morphology. Evident electrochemical improvement was nevertheless achieved that with gas shrouding the electrode exhibited similar performance as that of the VPS sprayed electrode.