EFFECT OF THIOUREAS ON CORROSION OF BRASS IN NITRIC ACID.

Abstract

The corrosion behavior of brass (60/40) in nitric acid containing thiourea and its N-substituted derivatives such as allylthiourea, methylthiourea, dimethylthiourea, phenylthiourea and diphenylthiourea, has been investigated using weightloss and polarization techniques. The inhibitor efficiency of each addition agent was found to depend on a) the concentration of nitric acid, b) temperature of the medium c) stirring rate of the solution and d) the nature of the inhibitor and its concentration. Two distinct mechanisms based on the concentration of HNO//3 are proposed to account for the mode of inhibitor action