Corrosion behaviours of iron-chromium-aluminium steel near the melting point of various eutectic salts

Abstract

The corrosion behaviours of Fe-Cr-Al alloy in four types of molten eutectic salts-chlorinated salt, carbonate salt, mixture of carbonate salt and MgO and nitrate salt-have been investigated in this paper. The experimental temperatures were chosen to be near the melting points of various eutectic salts and the longest holding time was sustained to 30 days in the isothermal experiments. The microstructures of the samples before and after corrosion tests were detected by X-ray diffraction and scanning electron microscope techniques. The research indicates, among the three eutectic salts, the corrosion of Fe-Cr-Al alloys in the molten chlorinated eutectic salt is the strongest with the thickness of corrosion scales between 40 and 180 μm. The corrosion in molten carbonate eutectic salt is relatively moderate, and the corrosive thickness is between 2 and 8 μm. For the molten nitrate eutectic salt, no obvious corrosion with special morphology was observed. The corrosion strength of the four eutectic salts should be in the order of chlorine eutectic salt > (carbonate eutectic salt + MgO) > carbonate eutectic salt > nitrate eutectic salt.