Guo Yongchun

Effect of Sn on Microstructure and Electrochemical Properties of Mg Alloy Anode Materials

Abstract Morphologies, microstructure and composition distribution of the magnesium anode materials were studied by metallographic microscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The corrosion behavior and electrochemical properties of Mg alloy were also investigated by constant current method, potential polarization, and drainage. The results show that Sn and Pb can restrain β-Mg17Al12 phase precipitation along the grain boundary and Mg-Al-Pb-Sn magnesium alloys have uniform and fine grain size. With the content of tin increasing, the content of particle Mg2Sn phase increases. After uniform heat treatment, most of β-Mg17Al12 phase dissolve, while most of Mg2Sn and Mg2Pb do not dissolve. The tin can improve self-corrosion potential and reduce release hydrogen rate. Magnesium anode has high discharge potential and current efficiency with 2wt% tin. With the current density increasing, the release hydrogen rate improves, owing to negative variance effect of magnesium alloys. The current efficiency is up to 88% at 10 mA/cm2. The main composition of the corrosion products are Mg(OH)2, SnO2 and MgSnO3 that are easier to peel off, which leads to more negative and stable work potential and can accelerate reaction continuously.

Preparation of Al/SiC Composite Coatings on Surface of Aluminum Alloy by Atmospheric Plasma Spraying

Abstract Al/SiC composite coatings were deposited on the surface of aluminum alloy by atmospheric plasma spraying. The effects of SiC volume in Al/SiC composite powders on the deposition behavior and the properties of the Al/SiC coatings were investigated. It is found that the decarburization and oxidation of pure SiC powder occur in the plasma flame. With the increase of SiC content, the deposition of the Al/SiC composite powder becomes more difficult through plasma spraying. There exist cracks between the bond coat and the aluminum alloy substrate resulting in poor adhesion between them. The hardness of the composite coating becomes higher with the increase of SiC content. The Al/SiC (50:50) deposit with a thickness of 70 μm and a hardness of 3690 MPa can strengthen the surface of aluminum alloy.

Effect of Carbon Target Current on the Microstructure of Cp/AlSn Films Deposited via Magnetron Sputtering

Abstract Cp/AlSn composite coatings were deposited with 0.2 A to 0.8 A carbon target current on a bearing alloy and single crystal Si (100) wafer via unbalanced magnetron sputtering. X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the phase compositions, the morphologies and the chemical states of the deposited films, respectively. Results show that the composite coating has equiaxed crystal. The phases of Cp/AlSn films consist of homogeneously mixed aluminum, tin and carbon. The XPS spectrum of the deposited Cp/AlSn films confirms that aluminum and tin exist mainly in the form of pure metals, and carbon element is composed of sp2 and sp3 bonds, among which sp2 is the main bond.