Study On Corrosion Behavior Of High Silicon Chromium Iron In The Soil Solution

The stability of the substation grounding grid is of great significance to the safe and reliable operation of the power system and the safety of transmission and transformation equipment.The grounding device is an important part of the grounding grid,and its corrosion resistance plays a vital role in the stable operation of the substation.Since the grounding device is buried in the ground for a long time,it is easy to be corroded by the soil.When the corrosion of the grounding device is severe,it may cause damage to the transmission line,threaten the safe operation of the power grid system,and then cause serious economic losses and even threaten the safety of human life.In recent years,high-silicon chromium iron(HSCI)has been gradually applied to the feeder rods of high-voltage converter stations and has become a practical material for grounding devices.However,research on its service behavior in the actual soil environment is still rare.In this paper,the electrochemical morphology,scanning electron microscope and ultra-depth 3D microscopy system were used to compare the morphology and composition corrosion characteristics of HSCI and Q235 in the neutral soil solution.The corrosion mechanism of HSCI in different solutions was discussed.The main research results are as follows:1.In the neutral soil solution,the surface of the Q235 steel showed obvious local corrosion characteristics after immersion for 720 h,and the surface corrosion products were mainly iron oxides.The surface corrosion of HSCI is mainly concentrated in the place where the shape changes sharply around the original hole,and no obvious corrosion is seen in the rest.The surface corrosion products are mainly Fe oxides,Si oxides and Cr oxides.Compared with Q235 steel,HSCI has higher corrosion potential,higher corrosion current density,higher polarization resistance value,and lower corrosion rate,indicating that HSCI has higher corrosion resistance in soil solution.The cathodic cycle curve shows that the cathodic polarization has a greater influence on the corrosion reaction of Q235 steel.2.In the acidic and alkaline soil solution,HSCI has high corrosion resistance.The high content of Cr and Si is beneficial for the high corrosion resistance of HSCI.The anode and the cathode polarization branches of HSCI in the acidic and alkaline soil solution is mainly dominated by the electrochemical polarization.However,thecorrosion rate of HSCI in the acid soil solution is higher than that in the alkaline soil solution.3.The HSCI surface defects in the soil solution greatly promote the soil corrosion process.Reducing the number of surface defects in HSCI may be beneficial to further improve their corrosion resistance.