Microstructure and Corrosion Resistance of Anodized Mg-9 mass%Li-1 mass%Zn Alloy

Abstract

This research used pulse and direct current methods to perform surface anodizing treatment of Mg-9 mass%Li-1 mass%Zn alloy (LZ91). The anodic films were analyzed with electrochemical impedance spectroscopy (EIS) for corrosion resistance. The impedance measurements show that the resistance value of anodic films made by pulse current to be 100 K at 2 Â 10 À2 A/m 2 and those made by direct current anodic films to be 65 K at 2 Â 10 À2 A/m 2 . It reveals that pulse current makes better anodic films than direct current. There were two layers in the anodic films that were verified from the EIS phase angle diagram in which three time constants existed. The structure of the film was analyzed by a FE-SEM, and the microstructure observation showed that the anodic film consists of porous and barrier layers.

Evolution of Corrosion Products Formed during the Corrosion of MgZr Alloy in Poral Solutions Extracted from Na-Geopolymers Used as Conditioning Matrix for Nuclear Waste

“…Magnesium silicates and brucite are known to reduce the magnesium corrosion [3,[7][8][9]. Nevertheless, such phases can present various and complex porous form.…”

“…As the pH of the poral solution coming from geopolymers is around 12, this passive film may be formed, which would explain the decrease of the corrosion rate of Magnesium alloys embedded [5,6]. Second, the presence of dissolved silica within the poral solution is also an asset since it was demonstrated that formation of magnesium silicates by an anodization process on the surface of magnesium improve its resistance regarding its corrosion [7][8][9]. In addition, some authors have shown that silicate sol-gel coating on Mg substrate induces reduction on corrosion [10,11].…”

Corrosion Resistance of Mg-Li Alloys Subjected to Different Heat Treatment

“…However, the corrosion of Mg-Li alloy is more serious than other Mg alloys because Li is very chemically active. The poor corrosion behavior has been a main factor preventing their further applications [1][2][3][4][5][6][7]. However, so far the understanding of the corrosion resistance of Mg-Li alloy is still not very clear.…”