Corrosion inhibition property study of mannich alkali and its combinational system in phosphoric acid medium

To solve the corrosion in phosphoric acidizing,a kind of mannich alkali,DS-3,was developed by aminomethylation reaction.The corrosion inhibition effect of this alkali and its combinational system in phosphoric acid medium was measured by static weight loss measurement.Its corrosion inhibition mechanism was investigated by electrochemistry and SEM.The surface state change of N80 testing material before and after corrosion was analyzed.The study indicates that the combinational system of DS-3 and a kind of thiourea derivative show good conspiracy in corrosion inhibition in the environment of phosphoric acid medium.0.25% combinational system was added in 15% phosphoric acid at 90℃,and the corrosive rate was 0.82 g/(m2·h),anticorrosion efficiency of this combinational system was over 99%.Electrochemistry study manifests DS3 and its combinational system reacted by restraining anode corrosion process.Observation from SEM shows a tight and even layer of absorption film is formed on the surface of the testing material when DS-3 combinational system is added into phosphoric acid.