Effect of Na₂SiO₃ concentration on microstructure and corrosion resistance of MAO coatings prepared on Al-Mg-Sc alloys

Abstract

Purpose The purpose of this paper is to investigate the effect of Na2SiO3 concentration on the microstructure and corrosive properties of microarc oxidation (MAO) coating on Al-Mg-Sc alloy and explore microstructure evolution rule of Al substrate in the contact area. Design/methodology/approach The Na2SiO3 concentration in electrolytes influenced the microstructure and corrosion behavior of MAO coatings. Instantaneous high temperature and high pressure due to microarc discharge caused annealing treatment. The corrosive behavior of the MAO coating was featured with polarization curves and electrochemical impedance spectrum in 3.5 Wt.% NaCl solution. Findings The substrate in the contact area existed the instantaneous annealing treatment, which caused obvious recrystallization. The coating prepared in electrolyte containing 7 g/L Na2SiO3 exhibited the highest protective properties in 3.5 Wt.% NaCl solution. Originality/value MAO treatment could increase the corrosion resistance by producing a protective layer on the Al-Mg-Sc alloy surface at a suitable Na2SiO3 concentration and microstructure evolution rule of Al substrate in the contact area was obtained.

Construction of superhydrophobic film on the titanium alloy welded joint and its corrosion resistance study

“…The surface of the welded joint matrix in Figure 7 (1–1) is mainly the crystal surface of Ti crystal, indicating that the element on that surface is Ti. As shown in Figure 7(1–2), the diffraction peak of the Ti matrix does not appear on the surface of Ti/MAO, but there is a crystal plane corresponding to anatase-type TiO 2 , which indicates that the surface belongs to anatase-type TiO 2 (Wu et al , 2022a; Liu et al , 2021).…”

Progress in superhydrophobic surfaces for corrosion protection of Mg alloys – a mini-review

“…The dipping method is a technique that involves immersing Mg alloy in different solutions to form a hydrophobic surface. An SHPS with a u c of 155.7°was prepared on Mg alloy after twice dipping treatment for 10 s in a solution containing aluminum phosphate and polytetrafluoroethylene (Wu et al, 2022a(Wu et al, , 2022b. The as-dipped SHPS resembles a coral reef structure and contains fluorocarbon groups, effectively reducing the corrosion rate of the substrate to 4%.…”

“…Reducing the contact area between the substrate and electrolyte can effectively decrease the corrosion rate of Mg alloy (Li et al , 2023). Some methods, such as chemical conversion (Yang et al , 2022), anode oxidation (Wu et al , 2022a, 2022b), metal plating (Jia et al , 2022) and hydrothermal method (Rahimi et al , 2021), are widely used for Mg alloy protection. In recent years, the superhydrophobic surface (SHPS) has proven to be a promising strategy for enhancing the corrosion resistance of Mg alloy in aqueous environments.…”

Study on the structure and corrosion resistance of MoS2/MgO micro-arc oxidation composite ceramic coating on the surface of ZK60 magnesium alloy

“…The author (Dr Chen) The surface morphology and corrosion resistance of MAO coatings are affected by different electrolyte compositions. The present electrolyte systems applicable to magnesium alloys mainly include silicates (Apelfeld et al, 2017;Wu et al, 2022), phosphates and meta aluminate. It has been shown that introducing micro-particles into the micro-arc oxidation electrolyte is an effective means of improving the structure and performance of the micro-arc oxidation coating.…”