Preparation of MgAlFe-LDHs as a deicer corrosion inhibitor to reduce corrosion of chloride ions in deicing salts

Abstract

This material consists of a double hydroxide consisting of Mg, Al, Fe in a 9:2:1 M ratios, which was synthesised by hydrothermal method under constant pH conditions. The products were calcined at 500 °C for use as a deicing corrosion inhibitor, which breaks through the problem that the traditional corrosion inhibitor itself doesn’t have the capability of deicing. The raw material of Al and Fe was extracted from the red mud by acid leaching. Characterization by XRD, FTIR, BET, XPS, SEM and TEM revealed that the interlaminar structure of the collapsed double-layered hydroxide material after high temperature calcination was regained by adsorbing Cl-. Cl- was filled between the layers of double hydroxide and existed by chemical adsorption. By measuring the freezing point of mixed deicing salt and the ability to melt snow and deicing, the freezing point of the inhibitor was found. When the solution concentration was 40 wt%, the freezing point of the mixed deicing salt reached −27.6 °C. Corrosion inhibitors can reduce the amount of CaCl2 when used in combination with anhydrous CaCl2. In addition, the determination of the corrosion rate of carbon steel and the resistance to salt freezing of concrete has revealed that the corrosion inhibitor can adsorb Cl- and reduce the content of free Cl- at low temperatures. Therefore, corrosion inhibitor plays a significant role in reducing the amount of Cl- used, the corrosion rate of carbon steel, and the salt-freezing resistance of concrete.