Fig. 1. SEM morphology of experimental powders. (a) 316L stainless steel powders; (d) ZrO₂-8%Y₂O₃ powders

Fig. 2. SEM images of the coatings surface. (a) Single-layer coating; (b) double-layer composite coating

Fig. 3. Cross-section morphology of substrate and double layer composite coating samples after polishing and etching. (a) Substrate; (b) double-layer composite coating

Fig. 4. SEM images of single-layer coating sample at different temperatures. (a) 200 ℃; (b) 400 ℃; (c) 1000 ℃

Fig. 5. SEM image and element distributions of single-layer coating sample. (a) SEM image; (b) element surface

Fig. 6. Electrochemical impedance spectroscopy of single-layer coating sample immersed in seawater for different time. (a) Nyquist diagram; (b) Bode plots

Fig. 7. Charge transfer resistance R_ct of single-layer coating sample immersed in seawater for different time

Fig. 8. Potentiodynamic polarization curves of substrate and coating samples immersed in seawater for 24 h

Fig. 9. SEM images s of corroded surface of single-layer coating sample immersed in seawater for 720 h

Fig. 10. SEM images s of corroded surface of double-layer coating sample immersed in seawater for 720 h