Improving electrochemical corrosion properties of ZE41A magnesium alloy via hydrothermal treatment

Abstract

ZE41A magnesium alloy was selected as matrix material, using hydrothermal method for the synthesis of the surface coating. The formation of anti-corrosion coatings on the surface of magnesium alloy was investigated in pure water. By adjusting the experimental parameters such as the hydrothermal time (1-3 h) and the hydrothermal temperature (120-160 °C), the generation of the coating on the magnesium alloy surface is regulated. The surface morphologies, composition phase, and corrosion resistance of the hydrothermal conversion coatings were investigated by the method of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and electrochemical corrosion tests. Results show that prolonged hydrothermal time and increased hydrothermal temperature change the morphologies as well as the chemical compositions of formed coatings from a relative loose structure with few magnesium hydroxides into a fine dense one with higher amount of magnesium hydroxide.

Electrochemical corrosion resistance of hydrophobic coatings on ZE41A magnesium alloy synthesized by hydrothermal method

“…It is clear that SA treated sample exhibits a relatively low corrosion resistance in 3.5wt.% NaCl solution. Its corrosion potential (E corr ) is -1.498 V and its corrosion current density (I corr ) is 9.085×10 -6 A• cm -2 , such parameters are similar to that of the previous study in which ZE41A was treated in pure water [13].With the addition of NiSO 4 in the hydrothermal solution, the SA+NiSO 4 treated sample shows better corrosion resistance. Its E corr shifts to a more positive value of -0.247 V and its I corr value decreases to 4.487×10 -7 A• cm -2 , which is only one twentieth of that of SA treated sample.…”