Effect and Mechanism of Benzotriazole for Cold Rolled Steel in 20% Acetic Acid Solution with Maximum Corrosive Concentration

The action and mechamism of benzotriazole(BTA)on cold rolled steel (CRS) in 20% acetic acid (HAc) with maximum corrosive concentration were investigated by tests of weight loss, polarization, electrochemical impedance spectroscopy, conductance and surface tension. The results revealed that BTA had surface activity and was an anodic controlled mixed-type inhibitor for CRS in 20% HAc, and the inhibition efficiency increased with the concentration of BTAC (BTA) increasing, and reached a maximum when CBTA was 400 mg/L, but above it, the corrosion rate had a gradual downtrend. The highest efficiency was present to the critical micelle of BTA. The adsorption of BTA was a spontaneous and exothermic process with entropy reducing and monolayer chemical adsorption before the formation of BTA micelles. After the formation of BTA micelles the CBTA continuously increasd and the remaining of BTA cations formed micelles aggregated with Ac-. There was a process of competitive adsorption among BTA and HAC. Temperature rising was beneficial to chemical absorption process of BTA.