High-temperature corrosion behavior of austenitic stainless steel in quaternary nitrate molten salt nanofluids for concentrated solar power

Abstract

Molten salt nanofluids have become a hot research topic due to its excellent thermal properties and heat transfer performance. However, there is a few research on the effect of nanofluids on the corrosion of metal materials. In order to know the influence of molten salt nanofluids on the corrosion of stainless steel, a low melting point quaternary nitrate was used as the base salt to analyze the corrosion law of nanofluids. By means of weight loss method, two different stainless steels (304, 316L) were put into the molten salt nanofluids with SiO 2 nanoparticles content of 1 wt% to test the corrosion behavior of stainless steel. The results of 500 h corrosion test revealed that the corrosion rate of mixed molten salt on 304 and 316L stainless steel is reduced by the addition of SiO 2 nanoparticles. The corrosion rates of molten salt nanofluids on 304 and 316L stainless steel were 0.0433 mm/y and 0.0233 mm/y, respectively. The surface morphology analysis by SEM, EDS, XRD and XPS test showed that the reticular silica nanostructures corrosion layer was formed on the surface of stainless steel, such structure can inhibit the corrosion of stainless steel. Therefore, molten salt nanofluids have the good compatibility with metal materials, and adding nanoparticles in molten salt can reduce the corrosion on stainless steel. • Investigating the corrosion behavior of stainless steels (304,316L) in the mixed molten salt and its nanofluids. • Confirming the corrosion reduction of stainless steel in the mixed molten salt nanofluids. • Discovering the nanostructure of reticulated SiO 2 in the corrosion layer of stainless steel. • Revealing the corrosion mechanism of stainless steel in the mixed molten salt containing SiO 2 nanoparticles.