The corrosion behavior of a wrought austenitic steel, Alloy 8001-1, was studied in a simulated coal-gasification atmosphere at 700~ for exposure times up to 2500 hr. The influence of preoxidation and CeOTsurface application followed by preoxidation on the corrosion resistance of this material was assessed. The improvement in the corrosion resistance due to preoxidation of the blank material was small, whereas the effect of the CeO2-treatment was significant. This difference is thought to be due to better scale adherence in the case of CeO2-surface application.

The corrosion behaviour of a number of Ni‐base alloys of different composition together with a highly‐alloyed austenitic stainless steel has been investigated with and without coating of the samples with alkali‐containing synthetic coal ash. The effects of various parameters have been studied, namely the Cr content (from 20 to 28 mass % Cr), the test temperature (700 and 775°C), the SO2 content in the gas (1 vol% and 0.25 vol % SO2) and the alkali sulphate content of the ash (10 and 30 mass%). The results can be explained on the basis of the differences in corrosion mechanisms resulting primarily from the composition of the alloys tested.

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