Corrosion of Nickel‐200 and AISI‐1008 Steel in Sodium Polysulfides and Sulfur at 350°C

Abstract

Tests were conducted to determine the corrosion behavior of nickel‐200 and AISI‐1008 steel in sulfur and sodium polysulfides (, , and ) at 350°C for times between 1 and 25h. Both the corrosion kinetics and the morphology of the corrosion scale formed on these metals are described. The corrosion of both metals is fast in these media, with the corrosion of nickel being up to twice as fast as that of iron. Changing the corrosion medium has little effect on the corrosion of nickel. The kinetics follow a logarithmic rate law in all cases, and the scale is multilayered with a porous inner layer. With the iron, however, the kinetics and the scale composition and morphology are significantly affected by the corrosion medium basicity. On going from sulfur through and to , the corrosion rate increases and the kinetics change from parabolic to almost linear while the scale changes from to a product of which appears as a band of small crystallites in the next to the metal.