Corrosion of Ferritic and Ferritic-Martensitic Steels in NaCl-KCl-VCl_2 Melts

摘要

The corrosion resistance of ferritic (08Kh17T) and ferriticmartensitic(12Kh13) type steels was investigated at 750 °C inNaCl-KCl-VCl_2 melts. The mechanism of corrosion of 12Kh1_3ferritic-martensitic steel in NaCl-KCl-VCl_2 melts includes twoparallel processes: formation of new excessive phases inducingFe_3C (σ-phase)|melt|steel microgalvanic pairs, and reaction of mostelectronegative steel components (Mn and Cr) with V~(3+) ionsformed due to disproportion of V~(2+). Contacting samples of08Kh17T with NaCl-KCl-VCl_2 melts resulted in no structuralchanges in the steel samples. In this case the mechanism ofcorrosion involves only one stage: disproportion reaction of V(Ⅱ)with the formation V-Fe alloy and V~(3+) ions and further oxidationof chromium in the steel by V(Ⅲ). It was shown, that the presenceof a suitable reducing agent in the contact with the melt (forexample, metallic vanadium) can prevent the steel destruction.