Corrosion Inhibition Effect of Mikania Micrantha Kunth Extract on Cold Rolled Steel in Sulfamic Acid Solution

The extract of mikania micrantha kunth (MME) was extracted from mikania micrantha powder with 40% ethanol aqueous solution as the extraction solvent. The functional groups of MME were analyzed by FTIR. The corrosion inhibition effect of MME on cold rolled steel in NH₂SO₃H solution was studied by weight-loss method, electrochemical analysis, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results showed that the corrosion inhibition effect of MME on cold rolled steel in NH₂SO₃H solution was remarkable. At 30 ℃, the corrosion inhibition rate of 100 mg/L MME to cold rolled steel in 0.1 mol/L NH₂SO₃H solution measured by weight loss method reached 92.2%. The adsorption law of MME on the surface of cold rolled steel obeyed the apparent Langmuir adsorption isotherm, and its standard adsorption Gibbs free energy on the steel surface was about -30 kJ/mol, there were physical adsorption and chemical adsorption at the same time. MME was a mixed inhibition corrosion inhibitor. After adding MME, the surface of the sample was smooth and uniform, and the corrosion degree was significantly reduced, which effectively slowed down the corrosion of acidic medium on the steel surface.