Inhibition roles of molybdate and borate on Q235 steel corrosion in resistance reducing agent

The effects of Na_(2)MoO_(4) and Na_(2)B_(4)O_(7) on corrosion behavior of Q235 steel in resistance reducing agent(RRA)containing sodium bentonite were studied by mass loss,scanning electron microscopy and electrochemical measurement.The results showed that both the independent and mixed additions of Na_(2)MoO_(4) and/or Na_(2)B_(4)O_(7),can reduce the corrosion rate of Q235 steel in RRA containing sodium bentonite.And the inhibition effect of Na_(2)MoO_(4) and/or Na_(2)B_(4)O_(7)increased with their dosage increase.With the same dosage,the inhibition efficiency of the mixed addition of Na_(2)MoO_(4) and Na_(2)B_(4)O_(7),was higher than that of their independent addition.The passivation effect of Q235 steel was easy to obtain in the RRA with the mixed addition of Na_(2)MoO_(4) and Na_(2)B_(4)O_(7).The optimized inhibitor for the RRA containing sodium bentonite was the mixture of Na_(2)B_(4)O_(7) and Na_(2)MoO_(4) with a total concentration of 1.5 wt.%.Furthermore,the increase in corrosion potential E_(corr) and the decrease in corrosion current density i_(cor) in carbon steel were one of the important criteria for the formation of passivation film.