Reduced-Oxide Titanium Coatings Prepared by Low-Temperature Atmospheric Plasma Spraying for PEM Water Electrolysis

Reduced-oxide titanium (Ti) protective coatings were fabricated on 316L stainless-steel substrates to improve the corrosion resistance of low-cost metallic components for proton exchange membrane water electrolysis (PEMWE). A low-temperature atmospheric plasma spraying process assisted by a self-designed extended protective nozzle was employed to suppress the oxidation of Ti particles during deposition. The nozzle provided auxiliary argon shielding and reduced the thermal exposure of in-flight particles, thereby limiting their interaction with ambient air. The deposited coatings exhibited a continuous lamellar structure with average thicknesses of approximately 78–98 μm. Phase and elemental analyses indicated that α-Ti(O) was the dominant phase, with limited oxide formation in the coating. ONH analysis further showed that the oxygen and nitrogen contents of the coatings were 0.95–1.69 wt.% and 0.049–0.087 wt.%, respectively. During the 6 h potentiostatic test, all Ti-coated samples showed lower and more stable current densities than bare stainless steel, with the 500 A 55 V coating maintaining the lowest final current density of approximately 0.4–0.5 mA/cm2. These results demonstrate that low-temperature atmospheric plasma spraying is a feasible and cost-effective approach for preparing reduced-oxide Ti coatings for PEMWE components.