Corrosion of Pure Cr and Ni–30Cr Alloy by Soda–Lime–Silicate Melts: Study of Simplified Systems

Abstract

The corrosion characteristics of model chromia-forming alloys (i.e. pure Cr and Ni–30 wt%Cr alloy) were studied in molten soda–lime–silicate (i.e. Na2O–CaO–xSiO2, x = 3 or 6, molar composition) at 1100 and 1150 °C using electrochemical techniques coupled with ex situ observations. High Cr activity of pure Cr led to high corrosion rates and also the inability of the material to develop a long term protective oxide scale after a preoxidation treatment. By contrast, the Cr2O3 scale built on preoxidized Ni–30Cr exhibited a protective behavior at 1100 °C. The variation of basicity of the silicate melts showed a minor influence on the corrosion behavior of both materials. An increase in the temperature up to 1150 °C led to higher solubility of Cr2O3, and thus did not allow the growth of a protective oxide scale on Ni–30Cr.