Papers by Author: Qiang Miao

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Authors: Qiong Jiang, Qiang Miao, Wen Ping Liang, Bei Lei Ren, Yi Xu, Zheng Jun Yao
Abstract: New waterborne Al-Zn-Si-RE coatings with improved corrosion resistance were introduced in this study. The corrosion resistance of Al-Zn-Si-RE coatings was evaluated by electrochemical measurements and salt spray test. Evolution of microstructure and phase composition at different exposure time in salt spray test was investigated by scanning electron microscopy and X-ray diffraction technique. The results indicate that Al-Zn-Si-RE coatings provide effective sacrificial protection to the steel substrate but exhibit lower corrosion rate and higher corrosion resistance compared to zinc aluminum coatings. The dense continuous corrosion layer formed on Al-Zn-Si-RE coating acts as a barrier layer, limiting the transport of aggressive species towards the coating-substrate interface and the corrosion rate of the coating; Zinc aluminum hydroxy carbonates are the dominant components in the corrosion layer of Al-Zn-Si-RE coatings.
1076
Authors: Qiang Miao, Cai E. Cui, Jun De Pan, Ping Ze Zhang
Abstract: Magnesium alloys exhibit great application potential in industries such as automotive, electronics, aerospace and others. But poor wear resistance and corrosion resistance have restricted their actual uses. In this study, a CrN film had been prepared on magnesium alloy AZ91 by arc-glow plasma depositing. The composition and microstructure of the coating had been analyzed by X-ray diffraction (XRD) and glow discharge spectrum (GDS). The morphology of CrN film has been surveyed through scanning electronic microscopy (SEM) and atom force microscopy (AFM). The wear behavior was investigated through ball-on-disc test. The corrosion behavior in 5 wt% NaCl solution was also studied. The results indicate that the specific wear ratio decreases greatly and the corrosion potential also increases relatively comparing to AZ91 matrix.
1789
Authors: Wen Ping Liang, Zhong Xu, Qiang Miao, Xiao Ping Liu, Zhi Yong He
Abstract: Ti2AlNb orthorhombic alloy is a promising high temperature structural material for aero-industries due to its advantageous properties. However, insufficient wear-resistance is a major drawback that has restricted the actual uses of this alloy in many circumstances. A treatment of double glow plasma surface chromizing on Ti2AlNb alloy has been carried out as an attempt to resolve this problem. This paper mainly investigated the electrochemical corrosion behaviors of this alloy after chromizing. The microstructure of the chromized layer was analyzed by X-ray diffraction (XRD). The sectional morphology of chromized layer was surveyed through scanning electronic microscopy (SEM).The polarization curves of specimens in three corrosive media, 5% H2SO4, 5% HCl and 3.5% NaCl, were measured. The eroded surface morphologies were also surveyed by SEM. The results indicate that surface chromizing treatment slightly decrease the alloy’s corrosion resistance, but still exhibit good performance.
1753
Authors: Wen Ping Liang, Zhong Xu, Qiang Miao, Zhi Yong He
Abstract: Ti2AlNb orthorhombic alloy is an attractive high temperature structural material for aero-industries, but insufficient wear-resistance is a major drawback which restricts the actual uses of this alloy in many circumstances. A double glow plasma surface molybdenizing on Ti2AlNb alloy had been carried out to resolve this problem. This paper investigated the electrochemical corrosion behaviors of the alloy after molybdenizing. The polarization curves of specimens in three corrosive media, 5% H2SO4, 5% HCl and 3.5% NaCl, were measured. The eroded surface morphologies were surveyed by SEM. The results indicate that surface molybdenizing decreased the alloy’s corrosion resistance slightly, but still exhibit good performance.
1793
Authors: Dong Bo Wei, Jun Huang, Ping Ze Zhang, Zheng Jun Yao, Qiang Miao, Xiao Xin Wei, Feng Ying, Guo Xian Yin
Abstract: A dense hot-dipping Al-Zn-Si-Re-Mg coating was prepared on the surface of steel sheet. The microstructure and toughness of coating were investigated by SEM and Nano-indentation test. The polarization curve of coating was acquired in static 3.5 wt.% NaCl solution in air at 25°C. The results show that Re and Mg improve the corrosion resistance and toughness of Al-Zn-Si coating. The formation of passive film on surface of Al-Zn-Si-Re-Mg coating is easier than that of Al-Zn-Si coating. Re decreases the number of oxygen existed in the coating. Mg3Al2(SiO4)3 depresses the porosity of coating, which is a glassy compound and formed in hot-dipping process.
1775
Authors: Cai E. Cui, Qiang Miao, Jun De Pan, Ping Ze Zhang
Abstract: Arc-aided glow discharge plasma penetrating technique is a new surface coating method. With the help of vacuum arc discharge, a cold cathode arc source continually emits ion beams of coating elements with high currency density and high ionizing ratio. As the ion bombard working on, nitrogen is let in the chamber simultaneously. Then the surface of the parts formed ceramic coatings. Under lab condition, a commercial magnesium alloy Az91 had been coated with TiN film layer with the aim of improving the corrosion resistance. This paper mainly summarizes the testing and analyzing of the coating layer. The composition and microstructure of the coating layer had been analyzed by means of X-ray diffraction (XRD) and glow discharge spectrum (GDS), and the surface appearance had been surveyed by scanning electronic microscope (SEM). The adhesion strength between film and matrix had been evaluated by experiments of sticking-tearing. The results indicated that the coated layer on magnesium alloy were homogeneous, dense and robustly adherent.
669
Authors: Dan Yang Zhu, Wen Ping Liang, Qiang Miao, Kai Guo, Long Li
Abstract: In order to improve the wear resistance of Ti2AlNb orthorhombic alloy, the carburized coating has been successfully prepared on Ti2AlNb alloy by double glow plasma technology. The microstructure, chemical composition and phase structure o f the carburized coating were analyzed by means of SEM, EDS and XRD. The Micro hardness of the alloy layer was measured, and the bond strength of carburized coating with substrate was also evaluated by scratch test. The tribological behaviors of layer were investigated by friction-wear test. The results show that a carburized layer is formed which is about 40μm and the content of C gradient decrease after double glow plasma carburizing, the Micro hardness of the layer is 1051 HV0.1 and the bond of the coating is 62N, the tribological behavior of layer is much better than matrix.
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