Study On Preparation And Corrosion Inhibition Performance Of Grounding Grid Resistance Reducing Agent

The resistance-reducing agent,which has been written into the national standard due to its good resistance reduction effect,is a kind of auxiliary material to reduce grounding resistance.The performance of resistance-reducing agent usually has low resistance,stability,corrosion resistance and environmental protection,etc.In China,grounding grid is mainly made of carbon steel,and the resistance-reducing agent is widely used especially in high soil resistivity areas.But a lot of studies and field examples show that the stability and corrosion resistance of most resistance-reducing agents are not up to the national standard.Aiming at the problems of the current resistance reducing agent,such as strong corrosion and poor stability,a new type of composite material,namely montmorillonite/polypyrrole(MMT/PPy),was synthesized by chemical oxidative polymerization,and the new type of macromolecular resistance reducing agent has been prepared by adding corrosion inhibitor into the MMT/PPy.Control variable method and weight loss method have been used to study the optimal formulation of the resistance reducing agent.Infrared spectroscopy(FTIR),scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)were used to characterize and analyze the materials.The corrosion current density of three kinds of resistance reducing agent was measured by linear polarization technique using Q235 carbon steel as working electrode,the corrosion rate of Q235 was obtained and corrosion rate of Q235 in 60 d was obtained by weight loss method.In addition,according to industry standard,the water loss experiment,hot and cold cycle experiment and immersion test of resistance-reducing agent were carried out.Meanwhile,the outdoor experiment was also performed to study the stability of the resistance-reducing agent.The results of the study were as follows:(1)The optimal formulation for MMT/PPy composites is MMT20%~25%,Hexadecyl trimethyl ammonium Bromide(CTMAB)5%~8%,Sodium p-toluenesulfonate(TASNa)12%~14%,Pyrrole(Py)5%~8%,FeCl3 45%~50% and the optimal corrosion inhibitor is Na3PO4.The volume resistivity of the new type ofmacromolecular resistance reducing agent can reach 1.34 ?·m.(2)Structural characterization indicates that the PPy has been intercalated into the interlayer of MMT to form a stable structure in the process of forming the composite materials.(3)The corrosion resistance of the new type macromolecule resistance reducing agent is low,and the corrosion rate of Q235 is about 0.017mm/a,which is in line with the national standard.And the corrosion of the other two kinds of resistance reducing agent is not up to standard.(4)The resistance reducing and stability of the new macromolecule resistance reducing agent are excellent,the resistance reducing rate is 82%,and the resistance reducing rate is still 80.74% after 60 days,which exceeds the industry standard.While the other two kinds of resistance reducing agent,although the resistance reducing rate is higher,but the stability is poor,the resistance reducing rate is only maintained at50.35% and 60.39% after 60 days.