Anticorrosion Performance of LDH Coating Prepared by CO₂ Pressurization Method

Figure 9

Optical corrosion morphologies of the AZ91D alloy with and without conversion coating of immersing test in 0.6M NaCl: (a₁) nonimmersed original sample, (a₂) original sample immersed for 24h, (a₃) original sample immersed for 48h, (a₄) original sample immersed for 72h, (a₅) original sample immersed for 120h, (b₁) nonimmersed CO₂_24h sample, (b₂) CO₂_24h sample immersed for 24h, (b₃) CO₂_24h sample immersed for 48h, (b₄) CO₂_24h sample immersed for 72h, (b₅) CO₂_24h sample immersed for 120h, (c₁) nonimmersed CO₂_2h /pH11.5_2h sample, (c₂) CO₂_2h/pH11.5_2h sample immersed for 24h, (c₃) CO₂_2h /pH11.5_2h sample immersed for 48h, (c₄) CO₂_2h /pH11.5_2h sample immersed for 72h, (c₅) CO₂_2h /pH11.5_2h sample immersed for 120h, (d₁) nonimmersed CO₂_3MPa_0.5h sample, (d₂) CO₂_3MPa_0.5h sample immersed for 24h, (d₃) CO₂_3MPa_0.5h sample immersed for 48h, (d₄) CO₂_3MPa_0.5h sample immersed for 72h, and (d₅) CO₂_3MPa_0.5h sample immersed for120h.