Corrosion Behavior And Mechanisms Of Ni-Fe-M Alloy In Molten Chloride Salt

In the field of concentrating solar energy,the intermittent solar energy is the main factor restricting the efficiency of solar power generation.Using molten salt as heat storage medium can improve the efficiency of solar power generation.However,molten chloride salts have strong corrosiveness to metals.In order to improve the corrosion resistance of solar energy storage vessel,a new type of Ni-Fe alloy,Ni-Fe-Al alloy and Ni-Fe-Sc alloy were proposed in this paper.The corrosion mechanism of the alloy in molten NaCl-MgCl₂ at 520?was analyzed by SEM,EDS and XRD.The results are as follows:?1?The corrosion behavior of pure Ni,pure Fe and Ni-Fe binary alloys with different Fe contents?9 kinds in total?in melting NaCl-MgCl₂?520??under air condition was studied.The results showed that the corrosion rate of the alloys decreased with the increase of Ni content.The optimum composition range of Ni-xFe was determined to be Ni-25 wt%Fe.?2?The corrosion mechanism of Ni-25 wt%Fe-Al?wt%:2,5,15,22,30?in NaCl-MgCl₂?520??in air was studied.The results show that Al is more active than Ni and Fe,which loses electrons and chlorinates to escape from the corrosion system.At the same time,MgO takes precedence over Al₂O₃ due to the presence of Mg²⁺in molten salts.The corrosion rate of Ni-Fe alloys after adding Al decreases with the increase of Al content.?3?Sc?0.0,0.3 and 0.5 wt%?was added to Fe-37 wt%Ni.The corrosion behavior of Fe-37 wt%Ni-Sc in molten NaCl-MgCl₂ at 520?was studied.The results show that with the increase of Sc content,the amount of MgO adhering to the alloy surface increases,and the adhesion between MgO and matrix increases.Sc₂O₃ is formed as the nucleation core of MgO,and plays a pinning role between MgO and alloy matrix.The corrosion resistance of the alloy increases with the increase of Sc content.In this paper,the corrosion behavior of Ni-Fe alloy,Ni-Fe-Al and Ni-Fe-Sc in molten NaCl-MgCl₂ at 520?has been studied.The research will promote the high value utilization of molten NaCl-MgCl₂ and transform the advantages of salt lake resources in Qinghai Province into economic advantages.