Fig. 8: SVET results of different coatings in 3.5 wt% NaCl solution.

SVET current density maps of a–c the WPU coating, d–f WPU–GORM coating, and g–i WPU–GOLM coating immersed for 2, 7, and 14 h, respectively. j The WPU coating was immersed for 24 h and it was immersed again after being heated at 60 °C for 6 h for k 1 and l 24 h, respectively.