Pitting corrosion of AISI 420 stainless steel in detergent–disinfectant solutions based on Catamine AB. Inhibiting effect of sulfate ions

• V.N. Dorofeeva, A.I. Shcherbakov, I.G. Korosteleva, I.V. Kasatkina, L.P. Kornienko and V.E. Kasatkin

A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, 119071 Moscow, Russian Federation

Abstract: The possibility of pitting corrosion of AISI 420 stainless steel in solutions based on Catamine AB is considered. It has been shown that at the concentrations of Catamine AB used in practice, there is a possibility of pitting corrosion. This probability increases with an increase in Catamine AB concentration. Catamine AB is a commercial product used for processing various materials, including steels, for the purpose of washing and disinfection. The product contains chlorides in the form of quaternary ammonium salts. Chlorides can be the cause of pitting corrosion. In this paper, the resistance to pitting of AISI 420 stainless steel used in medical devices has been investigated. The influence of Catamine AB concentration range recommended by the manufacturer has been studied. The studies were carried out with the polarization curves of the forward and reverse sweep. The dependence of the pitting formation potential on the concentration of Catamine AB, which is described by a straight line in logarithmic coordinates, has been obtained. Based on this dependence, three areas of Catamine AB concentrations can be distinguished for which it is possible to predict the different behavior of steel in relation to pitting. The first area of low concentrations of the product provides complete resistance to pitting formation. In the region of average concentrations of Catamine AB, pitting is possible when the potential is shifted to the anodic region due to a decrease in cathodic depolarization. And finally, in the third area of high product concentrations, steel is unstable to pitting. Thus, the concentration range recommended for use by the manufacturer includes the area of occurrence of pitting even on stainless steel. The possibility of increasing the threshold concentration of Catamine AB by adding sulfates to the solution has been studied. The results showed that although a certain positive effect can be achieved, it is not as great as we would like, since too much sulfate is required to suppress pitting corrosion. This is hardly acceptable due to the possible deterioration of the consumer properties of the product.

Keywords: Catamine AB, pitting corrosion, steel AISI 420 (40X13), inhibitor, sulfate ions

Int. J. Corros. Scale Inhib., 2022, 11, no. 2, 659-665
doi: 10.17675/2305-6894-2022-11-2-14

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