The Corrosion of Various Materials under Chloride Deposits at 623-723K in Pure Oxygen

Abstract

Corrosion problems in waste incinerators or in other advanced combustion power generation systems are usually rather serious due to the deposition of ashes composed of heavy and alkali metal chlorides or sulfates of metals such as Zn, K, Pb etc. This paper presents the individual and combined effects of ZnCI2and KCl on the corrosion behavior of some heat-resistant steels, the M38G Ni-based alloy, 2205 duplex steel and several other Fe-based alloys as well as pure metals were examined at 623K and 723K in pure oxygen. All the materials tested suffered from accelerated corrosion due to the formation of non-protective porous oxide scales and in many cases from local attack in the alloy matrix induced by chlorine. The Cr addition to the alloys can hardly provide sufficient corrosion resistance against such environments as a result of the bad adherence of Cr2O3to the alloy matrix. This detrimental effect is discussed on the basis of thermodynamic considerations. © 2002, by Walter de Gruyter GmbH & Co. All rights reserved.