| The inhibitive effect of single and composite inhibitors on carbon steel was studied in 20-wt%sodium chloride solution by weight loss, polarization curves,EIS and SEM.The results indicated that the inhibitive efficiency of sodium hexametahposphate which was used alone was only 74.2%.Sodium hexametahposphate was compounded with sodium benzoate,sodium tungstate,sodium phosphate and sodium silicate.The inhibitive efficiency of composite inhibitor of sodium hexametahposphate and sodium silicate was best.The mass ratio of sodium hexametahposphate to sodium silicate was 2:1,the concentration of composite inhibitor was 6.0g·L-1,and the inhibitive efficiency was 97.2%.Film was formed on the surface of carbon steel,and inhibited it from being corrosion.Drying and wetting process for carbon steel was imitated in deicing salt solution added different kinds of inhibitors.Corrosion rate of carbon steel was researched by dry/wet cyclic laboratory study.After 30 cycles, inhibitive efficiency of composite inhibitor of sodium hexametahposphate and sodium silicate was high.The surface of carbon steel was observed.It was bright as before.The composite inhibitor had synergy on carbon steel.Different components of deicing salt have different application temperature.In order to meet the requirements of winter lower temperature,inhibitive effect of deicing salt(the weight ratio of sodium chloride to magnesium chloride is 9:1)added sodium hexametahposphate,D-sodium gluconate and sodium tungstate on carbon steel was studied.Synergy action of composite inhibitor was researched by orthogonal design experiment,and the best concentration and ratio of each component were fixed.The results showed that usage amount of optimized inhibitor was reduced and its inhibitive efficiency was higher.The concentration of sodium chloride was unchanged,the concentration of D-sodium gluconate was down from 0.6g·L-1to 0.4g·L-1 and the concentration of sodium tungstate was down from 6.0g·L-1to 4.0g·L-1.
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