Corrosion Inhibition Performance of Thiourea/Potassium Thiocyanate Compound Inhibitor for Brass and Copper

The corrosion inhibition behaviors of compound pickling inhibitor using thiourea and potassium thiocyanate as composite components for brass and copper in 10% nitric acid, 10% sulfuric acid and 10% hydrochloric acid media were studied using the static weight loss, Tafel polarization curve and EIS tests. The mass ratio of thiourea to potassium thiocyanate in compound inhibitor and the dosage of the compound inhibitor have reatively great impact on the corrosion inhibition efficiency for the brass and copper. Experimental results show that the optimal mass ratio of thiourea to potassium thiocyanate was 6∶4 in the above-mentioned three pickling media. Wherein, the optimal dosage of compound inhibitor was 0.09% in 10% nitric acid medium, while in 10% sulfuric acid and 10% hydrochloric acid, the optimal dosage of compound inhibitor was 0.15%. Tafel polarization curves show that the addition of compound inhibitor can significantly reduce the corrosion current density of brass and copper in hydrochloric acid, sulfuric acid and nitric acid solution, indicating that compound inhibitor has the function of suppressing the cathodic and anodic reactions simultaneously.