The Effect of Silicon Addition on the High Temperature Oxidation of a Fe-Cr Alloy

摘要

The effect on the corrosion resistance of adding 0.15 wt.% silicon to a Fe-Cr alloy was examined at 1173 K in an H_2/Ar atmosphere containing 0.7% water vapour for 24 h. The oxide scales formed on the Fe-Cr alloys with and without silicon addition consisted of chromia. Furthermore, the addition of silicon resulted in the formation of small distinct silica particles near the alloy/chromia interface. The amount of silicon added to the iron-chromium alloy appeared to be insufficient to form a continuous silica layer beneath the chromia scale under the present experimental conditions. Although the silica particles did not form a continuous silica layer beneath the chromia scale, the growth rate of the chromia scale decreased due to addition of silicon. Different oxidation mechanisms are proposed and discussed in order to explain the reduced growth rate of the chromia scale after the addition of silicon to the alloy.