Abstract
Nano Al films were prepared on AZ31 magnesium alloy samples by DC magnetron sputtering. The effects of sputtering power on the microstructure and corrosion resistance of the Al film were investigated. The results show that the surface of aluminum film is dense and polycrystalline state, and it is oriented along the Al (111) crystal plane. The grain size of Al film first increases and then decreases with the increase of sputtering power. When the sputtering power exceeds 100 W, there is no insignificant effect on the orientation of the Al crystals and the corrosion current density of the samples with Al film are reduced by two orders of magnitude. The corrosion resistance of the magnesium alloy samples with the Al film magnetron sputtered varies with the sputtering power. Compared with low sputtering power, the Al film sputtered by high power has the most excellent corrosion resistance, but too high sputtering power will lead to micro cracks on the Al film, which will adversely affect the corrosion resistance.
Highlights
As a structural material, magnesium alloy has attracted more and more attention from the industry because of its advantages of light weight, high specific strength, good electrical conductivity, good electromagnetic shielding performance, good biocompatibility and easy recycling
The AZ31 magnesium alloy sheet was cut into small blocks of 10 mm × 10 mm × 5 mm by electric discharge wire, which was used as the substrate for magnetron sputtering
Nano Al films were prepared on the surface of AZ31 magnesium alloy samples by DC Magnetron Sputtering, and the effects of sputtering power on the microstructure and corrosion resistance were investigated
Summary
Magnesium alloy has attracted more and more attention from the industry because of its advantages of light weight, high specific strength, good electrical conductivity, good electromagnetic shielding performance, good biocompatibility and easy recycling. The corrosion product Mg(OH) and H2 are produced by electrochemical reaction of magnesium and water in aqueous solution [8]. The poor corrosion resistance of magnesium and its alloy is mainly due to two key factors: (1) The high negative potential of magnesium will lead to continuous corrosion even in an anoxic environment; (2) the surface film formed on magnesium is less protective [9]. This means that any oxide or hydroxide layer formed on the surface of magnesium is soluble in most water environments or humidity conditions. According to the Pilling–Bedworth principle, the PB (oxide/metal volume ratio) ratio of MgO/Mg is 0.81 < 1, and the spontaneous oxide film cannot completely cover and effectively protect the surface of the magnesium metal substrate [10]
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