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Qu S.G.,South China University of Technology | Lou H.S.,South China University of Technology | Lou H.S.,Liuzhou Vocational and Technical College | Li X.Q.,South China University of Technology
Journal of Composite Materials | Year: 2016

In this paper, 60.5-68.0 vol.% SiCp/Al composites were prepared by infiltrating liquid aluminum into preforms. The average diameters of SiC particles used in the particles packing experiments were 45, 8 and 2 μm for the group I preforms, and 75, 8 and 2 μm for the group II preforms. The thermal-mechanical properties of the composites were investigated. The mechanical properties test showed that the tensile strength of the composites was in the range of 212-349 MPa, and the elastic modulus of the composites was greater than 150 GPa. For a given SiC volume fraction, the tensile strength and elastic modulus of the group I composites were greater than that of the group II composites. The thermal properties test revealed that the coefficient of thermal expansion of the composites was in the range of 10.33-12.32 × 10-6/°C, and the measured thermal conductivity of the composites was greater than 85.6 W/(m·°C). The change of the particle size distribution had no effect on the coefficient of thermal expansion, and the coefficient of thermal expansion decreased linearly with the increase of SiC content. An average diameter approach for estimating the thermal conductivity of the composites was proposed in the application of Hasselman-Johnson model. The results indicated that the predictions of the model were in good agreement with the measured thermal conductivity of the composites. © The Author(s) 2015. Source


Qu S.G.,South China University of Technology | Lou H.S.,South China University of Technology | Lou H.S.,Liuzhou Vocational and Technical College | Li X.Q.,South China University of Technology
Journal of Composite Materials | Year: 2015

SiC particles reinforced aluminum matrix composites (SiCp/Al) with SiC content of more than 60%, without particle segregation for mirror substrate applications, are prepared by using the improved process. The improved process contains sintering process design, preform quality traceability, and equipment designing. The maximum SiC volume fraction of 70.4% is obtained by optimizing the selection of the following proportion: 71.4% coarse, 7.1% medium, and 21.5% fine particles. The variation of SiC volume fraction is correlated with the percentage of fine particles by using regression analysis. The preforms with the compressive strength above 10.34 MPa are prepared by sintering at 1600°C for 2 h. Results showed that no defects in the scale of more than 10 μm are observed in the preforms. Due to the generation of a SiO2 layer during the sintering process, the formation of Al4C3 phase was inhibited. As the SiC particle volume fraction increased from 65.6% to 70.4%, the bending strength increased from 483.2 MPa to 585.2 MPa. The elastic modulus also increased from 174.2 GPa to 206.1 GPa, while the coefficient of thermal expansion between 50°C and 350°C decreased from 11.02 × 10-6/°C to 9.53 × 10-6/°C. © The Author(s) 2015. Source


Yu Q.,University of Sichuan | Yu Q.,Liuzhou Vocational and Technical College | Wang X.,University of Sichuan | Duan Y.,University of Sichuan
Analytical Chemistry | Year: 2014

A novel capillary-based three-dimensional (3D) fluoroimmunosensor for carcinoembryonic antigen detection was explored for the first time. The immunosensor was designed in symmetrical cylinder structure and fabricated with capillary tubes encapsulated in a quartz tube. The 3D design of the sensor increased the area of sensing surface, flexibility in light path design and efficiency of fluorescence collection by aluminum foil, resulting in analytical performance improvement. The CEA immunosensor was constructed in double antibody sandwich format. Fluorescence signals from DyLight 550-labeled antibody were measured using a laser-induced fluorescence spectrometry. There is an obvious improvement in the linear detection range of 0.7-80 ng/mL. This novel 3D immunosensor dramatically improved the detection limit (1.1 pmol/L CEA) and sensitivity. Assay validation studies indicated that the correlation coefficient reached 0.9935, with recoveries of 92.82-118.81%. Furthermore, the immunosensor was successfully applied to CEA determination in actual saliva specimens with high sensitivity and acceptable precision. Regarding accuracy, the results obtained by 3D immunosensor were not significantly different (t test) from those obtained by validated electrochemiluminescence immunoassay. This new 3D CEA immunosensor was demonstrated to be a high-performance tool for CEA diagnostics. © 2014 American Chemical Society. Source


Yang L.,Liuzhou Vocational and Technical College | Hua J.,Guilin University of Electronic Technology
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2016

The surface of AZ91 alloy engine cylinder was modified by surface plasma cladding. The micro-structure and phase constituent of AZ91 alloy substrate, TiB2-Al2O3 and varied Al: (TiB2-Al2O3) compound modified layer were analyzed, and the hardness, wear resistance and corrosion resistance of the modified layer were investigated. The results show that with the increase of distance from the surface of the modified layer, the micro-hardness of the modified layer is decreased gradually, however, the micro-hardness of the modified layer is the higher than that of AZ91 alloy substrate. The micro-hardness of the modified layer is decreased gradually with the increase of Al content, while the micro-hardness of TiB2-Al2O3 modified layer has the maximum value. With prolonging wear time, the wear weight loss of the substrate and modified layer are increased gradually, and the wear resistance modified layer with ω (Al): ω (TiB2-Al2O3) = 1:2 exhibits desirable. The corrosion resistance of the modified layer is improved compared with AZ91 alloy substrate, and the modified layer with ω (Al): ω (TiB2-Al2O3) = 1:2 has the satisfied corrosion resistance. © 2016, Journal Office of Special Casting and Nonferrous Alloys. All right reserved. Source


Yang L.,Liuzhou Vocational and Technical College
Jinshu Rechuli/Heat Treatment of Metals | Year: 2014

Taking the hot rolled Mg-Al-Sn alloy plate as the research object, the rolled samples were annealed at 250~450℃, the effects of grain size and strain rate on room temperature deformation behavior of Mg-Al-Sn alloy were analyzed. The results show that at the same strain, with grain size increasing, the yield strength, tensile strength and elongation of the alloy decrease, and the number of twins raise. With the increase of strain, the number of twins in the same grain size of the alloy increase gradually. With the strain rate decreasing, the yield strength and tensile strength of the alloy decrease, while the elongation increases. With the strain rate decreasing, the volume fraction of twins in the alloy decreases at the same strain. Source

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