SULFIDE-FORMING FEATURES DURING OXIDATION OF PREDEFORMED NICKEL IN SO2

Loaded parts ave exposed to hot corrosion to a greater extent than unl oaded components. Pure nickel predeformed to various degrees by compre ssion (up to 27%) has been oxidized in SO2 at 600 degrees C for differ ent periods (22 to 95 hr). A 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 estab lished for the same exposure (> 70 hr). the higher the preliminary str ain, the greater the amount of Ni3S2 in the scale. Nickel predeformed 21% and 27%, oxidized in SO2 over 70 hr, formed scales consisting main ly of a single-phase Ni3S2 layer. An increase of the scale defectivene ss accelerated attainment of heterogeneous equilibrium in a gas-scale system and intensified the formation of Ni3S2-the stable phase for the conditions used.