Sulfide-Forming features during Oxidation of Predeformed Nickel in SO_2

摘要

Loaded parts are exposed to hot corrosion to a greater extent than unloaded components. Pure nickel predeformed to various degrees by compression (up to 27%) has been oxidized in SO_2 at 600℃ for different periods (22 to 95 hr). It has been shown that transport properties of the scale, formed on the initial metal surface containing physical defects, depend on their surface density. A general behavior was established for the same exposure (> 70 hr): the higher the preliminary strain, the greater the amount of Ni_3S_2 in the scale. Nickel predeformed 21% and 27%, oxidized in SO_2 over 70 hr, formed scales consisting mainly of a single-phase Ni_3S_2 layer. An increase of the scale defec-tiveness accelerated attainment of heterogeneous equilibrium in a gas-scale system and intensified the formation of Ni_3S_2—the stable phase for the conditions used.