Corrosion of Mg alloys EV31A, WE43B, and ZE41A in chloride‐ and sulfate‐containing solutions saturated with magnesium hydroxide

Abstract

This study studied corrosion in 0.1 M Na 2 SO 4 , 0.1 M NaCl, and 0.6 M NaCl, all saturated with Mg(OH) 2 , using weight loss, hydrogen evolution, and electrochemical measurements. Corrosion was similar in all cases. Nevertheless, the corrosion rates were alloy-dependent, were somewhat lower in 0.1 M Na 2 SO 4 than in 0.1 M NaCl, and increased with NaCl concentration. The corrosion damage morphology was similar for all solutions; the extent correlated with the corrosion rate. The corrosion rates evaluated by the electrochemical methods were lower than those evaluated from hydrogen evolution, consistent with the Mg corrosion mechanism involving the unipositive Mg + ion. K E Y W O R D SEIS, hydrogen evolution, magnesium, polarization, SEM

Influence of commercial corrosion‐inhibiting compounds on the atmospheric corrosion of the magnesium alloys EV31A, WE43B, ZE41A and pure magnesium

“…In most cases, corrosion rates were significantly lower than 0.1 mm/year and lower than the intrinsic corrosion rate of Mg in a concentrated chloride solution of 0.3 mm/year. [ 12 ] These atmospheric corrosion rates were significantly lower than the corrosion rates measured in chloride and sulphate solutions [ 10,15 ] attributed to more protective corrosion product films formed during atmospheric corrosion.…”

“…The three Mg alloys, EV31A, WE43B and ZE41A, were supplied by Magnesium Elektron, Manchester, UK in the cast and heat-treated condition as in the prior research, [10,15] which is the condition used in military helicopters. The Mg alloys EV31A and WE43 had received the T6 treatment, while ZE41A was supplied in the T5 treatment.…”

“…The high corrosion rate for ZE41A was caused by microgalvanic acceleration by the T‐phase. Soltan et al [ 15 ] studied the corrosion of EV31A, WE43B and ZE41A in chloride and sulphate solutions. The corrosion rates were alloy‐dependent, were somewhat lower in 0.1 M Na 2 SO 4 than in 0.1 M NaCl and increased somewhat with NaCl concentration.…”

The corrosion inhibition mechanism of Ca(H2PO4)2 on AZ91D magnesium alloy in 3.5 wt% NaCl solution

“…The inductive loop is thought to be related to film formation and destruction or the relaxation process of adsorbed intermediates during corrosion. [42][43][44][45] When the concentration of Ca(H 2 PO 4 ) 2 is less than or equal to 0.6 g L À1 , the sum of the diameters of the two capacitive arc semicircles enlarges with the increase of Ca(H 2 PO 4 ) 2 concentration, and the inductance resistance gradually weakens, that is, the corrosion impedance increases, indicating that the corrosion inhibition has been improved. However, with the further increase of Ca(H 2 PO 4 ) 2 concentration, the sum of the diameters of the two capacitive arc semicircles begins to decrease.…”

“…R s stands for the solution resistance, R f stands for the resistance of corrosion product film and/or adsorption corrosion inhibitor film, n f stands for the deviation coefficient of the corresponding film, R ct stands for the charge transfer resistance, CPE f and CPE dl respectively stand for the capacitance of the surface film and the double-layer capacitance, n dl stands for the deviation coefficient of the corresponding double-layer capacitance, R L and L stand for the resistance and inductance corresponding to the tail. 44,46,47 The impedance (Z CPE ) is defined as follows:…”