The inhibitive action of Sodium tetra fluoroborate(NaBF4) on corrosion of carbon steel (CS) in 1.0M HCl was studied by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The measurements show that the inhibition efficiencies increase with the increasing of NaBF4 concentrations but decrease with increasing of the temperatures. This reveals that the inhibitive action of the inhibitor was mainly due to the adsorption on the carbon steel surface by blocking of the active sites. The above results showed that NaBF4 acted as a mixed-type corrosion inhibitor. The adsorption of NaBF4on the carbon steel surface obeyed the Langmuir adsorption isotherm. This was supported by the impedance measurements which showed a change in the charge transfer resistance and double layer capacitance, indicating the adsorption of NaBF4 on the carbon steel surface. Thermodynamic parameters of the studied inhibitor were calculated and discussed.
Keywords: Sodium tetra fluoro borate; Corrosion inhibition; Carbon Steel; Adsorption; EIS.