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The crevice corrosion behavior of 22% Cr duplex stainless steel (SS), which has become widely used because of its high strength and stress corrosion cracking (SCC) resistance, was investigated in simulated sour gas conditions. The crevice corrosion is accelerated with increasing partial pressure of H2S and temperature, decreasing pH of the test solution, and the addition of sulfur. The duplex SS was more resistant to the crevice corrosion than AIS1^1) 316 SS in the H2S-Cl-environment.A simple model of the crevice corrosion, in which the initiation process and the mode of crevice corrosion were discussed, was proposed. The crevice corrosion incubation time based on this model was calculated, and the effect of the crevice gap and the partial pressure of H2S was clarified. The mode of the crevice corrosion changed with the partial pressure of H2S, which was explained by the stability of the NiS film and the depassivation pH in the crevice.

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Films were prepared on stainless steel, aluminum alloy and glass substrates using silica precursor solution containing copper ions. The thickness of the lm coating was about 0.10.2 mm. The corrosion resistance was greatly improved by PVBcontaining silica coating onto stainless steel. An antimicrobial test based on Japanese Industrial Standard (JIS Z 2801) indicates that the antimicrobial activity (R) of a control silica coating is R0.0, whereas R5.0 for the coppercontaining silica coating (Cu: 6.1~10 |3 mol/L). JIS de nes antimicrobial activity as positive when R is more than 2.0. A submicron thick coppercontaining silica coating clearly impacts corrosion resistance and antimicrobial activity to a material surface without any heat treatment.