A Combined Inhibiting Effect of Sodium Alginate and Sodium Phosphate on the Corrosion of Magnesium Alloy AZ31 in NaCl Solution

Abstract

The inhibiting effect of joint-addition of sodium alginate (SA) and sodium phosphate (SP) on corrosion of magnesium (Mg) alloy AZ31 (3 wt% aluminum and 1 wt% zinc) in 3.5 wt% NaCl solution was investigated by electrochemical impedance spectroscopy, potentiodynamic polarization analysis, mass loss measurements, and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). Results reveal a combined inhibiting effect derived from the presence of SA and SP with respect to Mg alloy AZ31 and an optimal inhibition efficiency in terms of corrosion of AZ31 substrate was yielded in 3.5 wt% NaCl electrolyte containing 0.05 wt% SA and 0.15 wt% SP. SEM-EDS examination suggested that such a promising combined inhibiting mechanism could be attributed to the formation of a compact, homogeneous and protective composite film. Chemical composition study through Fourier transform infrared spectroscopy elucidates that such a protective film contains not only conventional magnesium hydroxide as a result of corrosion of Mg alloy AZ31, but SA and SP through chemical adsorption on the surface of Mg alloy AZ31.

Use of Cedrela odorata Linnaeus Exudate for Inhibiting Corrosion by Chlorides in Reinforced Concrete

“…Likewise, concrete samples containing pozzolans have significantly lower chloride content at different times, especially in deeper zones; this was previously reported by [41], [42].…”

Na2SnO3 functions as outstanding magnesium alloy passivator by synergistic effect with trace carboxymethyl chitosan for Mg–air batteries for standby protection

“…3.3 Comparative efficiency and the amount of inhibitors. According to previous studies [65][66][67][68][69][70][71][72][73][74][75][76] (the data in the literature are shown in Table 6), the inhibition efficiency of the corrosion inhibitor for the Mg alloy is mostly concentrated between 70% and 95%. In the current work, the maximum corrosion inhibition efficiency of 94.3% for the AZ61 alloy in NaCl solution was derived based on the hydrogen evolution tests by adding the mixed inhibitors (5.0 mM Na 2 SnO 3 + 0.1 mM CMCS); such efficiency is higher than that of most single inhibitors or inhibitor combination.…”

“…Among them, the use of inorganic salts such as Na 3 PO 4 , Na 2 SiO 3 , Na 2 WO 4 , Na 2 CO 3 , and KI (alone or in combination with other organic compounds) all had certain corrosion inhibitive effects on the Mg alloy in NaCl solution (their maximum efficiency are all greater than 76%). [65][66][67][68][69][70] The combination of 0.05 wt% sodium alginate and 0.15 wt% Na 3 PO 4 , and the combination of 0.03 M sodium alginate, 0.015 M Na 2 SiO 3 , and 0.02 M Na 2 WO 4 showed the maximum inhibition efficiency of 98.8% and 98%, respectively (Table 6), which are higher than the results of this study but their amount is much higher than the amount of Na 2 SnO 3 and CMCS in this study. Sodium alginate (organic inhibitor) was frequently mixed with inorganic salts to inhibit the corrosion of the Mg alloy in NaCl solution; it was shown that these schemes work pretty well but the amount of this organic inhibitor usually required far exceeded the amount of CMCS in this study to exert a close inhibition effect.…”

“…Sodium alginate (organic inhibitor) was frequently mixed with inorganic salts to inhibit the corrosion of the Mg alloy in NaCl solution; it was shown that these schemes work pretty well but the amount of this organic inhibitor usually required far exceeded the amount of CMCS in this study to exert a close inhibition effect. [66][67][68] It is worth noticing that most of the inhibitors reached maximum performance at higher concentrations, which further increases the associated inhibitor cost. On the other hand, we also found that the amount of organic inhibitor for the Mg alloy corrosion is relatively low; the combination inhibitors containing the organic inhibitor can reduce the total inhibitors used, and these organic inhibitors are suitable to be used in low-concentration NaCl solutions.…”

Critical review on development of magnesium alloy as anode inMg‐Airfuel cell and additives in electrolyte

“…In addition, the application additive on electrolyte is preferable. Various chemical electrolyte additives that may improve MAFC performance have been identified to date as reported in previous review papers 157‐161 . This paper focused on and compared four potential additives to improve the MAFC performance.…”