Investigation Of The Synergistic Effect Between BTA And Its Composite Corrosion Inhibitors On Copper

Copper and its alloys are widely used in industry as constructional or functional materials. But they are easily corroded and discolored when they are exposed to atmosphere, and thus the apparent and decorative performance of them is greatly affected. Corrosion inhibitor is an effective way to prevent the corrosion and discoloration of copper and its alloys. Benzotriazole (BTA) is the specific corrosion inhibitor for copper and its alloys. In this paper, we systematically discuss the synergistic effect between BTA and other compounds including inorganic compound, surfactant, organic polymer and the derivative of BTA, in order to reduce the dosage of corrosion inhibitors while maintaining their inhibition efficiency at a high level. The results are as follows:1 The corrosion capability of the composite inhibitor made from BTA and Na₂MoO₄/Na₂WO₄/La³⁺/Ce³⁺ on copper was studied by electrochemical polarization and static coupon tests. The results showed when the ratio of BTA to Na₂MoO₄/Na₂WO₄/La³⁺/Ce³⁺ was set at a specific value, the inhabition efficiency could be improved from 60% to more than 80%. After immersed in the ethanol solution of the composite system for 2 minutes, the copper specimen showed good performance against corrosion and discoloration in the atmosphere.2 The composite inhibitor of BTA with cationic surface active agent- Hexadecyltrimethylammonium Bromide (CTAB) was investigated. The inhabition efficiency and the optimum ratio of different systems were obtained by weight loss test. The electrochemical polarization curves and static coupon tests results showed that the inhibition efficiency of the composite inhibitors was about 45% higher than that of the single inhibitor. So it can be concluded that the two kinds of inhibitors have good synergistic effect with each other.3. The composite inhibitor of BTA with polymers- Polyvinylpyrrolidone (PVP) was investigated. The orthogonal test reveals that when the ratio of BTA to PVP was 2mmol/L:20mg/L and 5mmol/L:10mg/L respectively, the inhabition efficiency of the composite inhibitor reached 93.80% and 95.23% respectively. However, when the single inhibitor was used at the same concentration, the inhabition efficiency was only 60%. These results indicated the synergistic effect between BTA and PVP.4. N-alkyl benzotriazole (N-CBTA) was synthesized by one-step process with BTA and alkyl halides as raw materials. N-CBTA can be used as corrosion inhibitor on copper, but the effect was not obvious. When it was combined with BTA at the ratio of 9mmol/L:1mmol/L and 8mmol/L: 2mmol/L, the inhabition efficiency could reach 91.33% and 93.46%.This result proved that great synergistic effect existed between BTA and N-CBTA, they can interaction with each other to form a dense inhibitor coating which can prevent the corrosion of copper effectively.