Surface Analysis of Carbon Steel Protected from Corrosion by a New Ternary Inhibitor Formulation Containing Phosphonated Glycine, Zn<sup>2+</sup>and Citrate

• 作者: Bojja Sreedhar Boyapati Venkata Appa Rao Madala Venkateswara Rao Sirugudu Srinivasa Rao
• 来源期刊: 表面工程材料与先进技术期刊(英文)
• 学科: 医学
• 关键词: Carbon Steel CORROSION INHIBITOR Protective Film Synergism BPMG CITRATE
• 年，卷（期）: bmgcclyxjjsqkyw_2013,（1）
• 页码范围: 28-42
• 页数: 15页
• 分类号: R73

摘要

Studies on surface analysis of carbon steel protected from corrosion in low chloride and nearly neutral aqueous environment by a synergistic mixture containing N,N-bis(phosphonomethyl) glycine (BPMG), zinc ions and citrate ions are presented. The effect of addition of citrate to the binary system, BPMG-Zn2+, is quite significant and is well explored through various studies. The surface protective nature is maintained in the pH range 5 - 9. Potentiodynamic polarization studies inferred that the ternary inhibitor is a mixed inhibitor. Impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the chosen environment. X-ray photoelectron spectroscopic (XPS) analysis of the surface film showed the presence of the elements namely iron, phosphorus, nitrogen, carbon, oxygen and zinc. Deconvolution spectra of these elements in the surface film inferred the presence of oxides/hydroxides of iron(III), Zn(OH)2 and [Fe(III), Zn(II)-BPMG-citrate] heteropolynuclear multiligand complex. This inference is further supported by the reflection absorption Fourier transform infrared spectrum of the surface film. Analysis by scanning electron microscopy (SEM) is presented for both the corroded and protected metal surfaces. Based on all these results, a plausible mechanism of corrosion inhibition is proposed.