Chloride-induced depassivation and corrosion of mild steel in magnesium potassium phosphate cement. (September 2022)

• Record Type: Journal Article
• Authors: Wang, Danqian; Yue, Yanfei; Xie, Zhichao; Mi, Tangwei; Yang, Siyu; McCague, Colum; Qian, Jueshi; Bai, Yun
• Is Part Of: Corrosion science. Volume 206(2022)
• Publication Date: 2022-09
• Subjects: Chloride-induced corrosion -- Magnesium phosphate cement -- Mild steel -- Magnesia-to-phosphate ratio; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2022.110482
• Languages: English
• ISSNs: 0010-938X

Abstract

Abstract: This study investigated the chloride-induced depassivation and corrosion of mild steel in the magnesium potassium phosphate cement (MKPC) pore solutions at different magnesia-to-phosphate (M/P) ratios via several electrochemical methods and surface characterisations. Results showed that although the pH of MKPC is much lower than that of PC, the corrosion resistance of mild steel is significantly higher, with critical chloride values in MKPC being several orders higher than that in PC. Chloride-induced corrosion resistance increases with increasing M/P ratios. Whilst both pH and HPO4 2- /PO4 3- ions influence the formation of corrosion products, the pH plays a dominant role in the corrosion resistance. Highlights: Mild steel in MKPC shows much higher critical chloride values than that in PC. Corrosion resistance increases with increasing magnesia-to-phosphate (M/P) ratio. The corrosion resistance of mild steel is mainly determined by pH of MKPC, i.e., M/P. The PO4 3- ions in MKPC can inhibit the chloride-induced corrosion of mild steel. Different corrosion mechanisms are proposed for mild steel in MKPC with low and high M/P.