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Surface Nanocrystallization of Magnesium Alloy AZ91D by High-Energy Shot Peening

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Journal of wuhan university of technology(Materials science) 2009年第4期24卷 515-519页

作者：张津 school of Materials science & Engineering University of Science and Technology Beijing College of Materials science & Engineering Chongqing University of Technology

High-energy shot peening （HESP）, a method to produce severe plastic deformation by high velocity flying balls, was applied on die cast magnesium alloy AZ91D. Effects of surface nanocrystallization by HESP and heat treatment at different temperatures were investigated. The mi- crostructure evolution was conducted using X-ray diffraction （XRD） and field emission scanning electronic microscopy （FESEM）. The hardness was measured by microhardness tester. The experimental results show that surface nanocrystrallization of AZ91D obtained by HESP would lead to the increase of microhardness. Low temperature heated at 100℃ for 1 h do not change the property obviously. However, both the microstructure and microhardness vary greatly after heat treatment at 400℃ for 1 h.

关键词： AZ91 D surface nanocrystallization HESP microhardnss corrosion resistance

Deformation Resistance Effect of PAN-based Carbon Fibers

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Journal of wuhan university of technology(Materials science) 2009年第3期24卷 415-417页

作者：郑立霞 school of science Wuhan University of Technology

The deformation resistance effect of polyacrylonitrile （PAN）-based carbon fibers was investigated, and the variatipn law of electrical resistivity under tensile stress was analyzed. The results show that the gauge factor （fractional change in resistance per unit strain） of PAN-based carbon fibers is 1.38, which is lower than that of the commonly-used resistance strain gauge. These may due to that the electrical resistivity of carbon fibers decreases under tensile stress. In addition when the carbon fibers are stretched, the change of its resistance is caused by fiber physical dimension and the change of electric resistivity, and mainly caused by the change of physical dimension. The mechanical properties of carbon fiber monofilament were also measured.

关键词： PAN-based carbon fibers resistance strain gauge factor

Mold Filling Analysis in Vacuum Infusion Molding Process Based on a High-Permeable Medium

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Journal of Materials science & technology 2003年第5期19卷 467-471页

作者： Yingdan ZHU, Hua TAN and Jihui WANGState Key Laboratory of Advanced technology for Materials Synthesis and Processing, wuhan university of technology, wuhan 430070, china State Key Laboratory of Advanced technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

The objective of this paper is to understand the flow mechanism through visualization experiments and discuss theinfluence of process parameters on mold filling process. A 2D leakage flow model is developed to simulat... 详细信息

关键词： Vacuum infusion molding process (VIMP) High-permeable medium Mold filling Simulation

Preparation and Characterization of Chitosan/Carboxymethylated Konjac Glucomannan Blend Films

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wuhan university Journal of Natural sciences 2002年第1期7卷 107-112页

作者： Zheng Hua 1 , Du Yu-min 2 1. Department of Chemical Engineering, wuhan university of technology, wuhan 430070, Hubei, china 2. College of Chemistry and Molecular sciences, wuhan university, wuhan 430072, Hubei, china wuhan university of technology Department of Chemical Engineering Wuhan Hubei China (GRID:grid.162110.5) (ISNI:***) wuhan university College of Chemistry and Molecular Sciences Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***)

In order to improve the mechanical and water swelling properties of the chitosan (CS) film, a series of transparent films were prepared by blending 2%(weight) chitosan acetic acid solution with 1.5%(weight) carboxymethylated konjac glucomannan (CMKGM) aqueous solution according to predetermined ratio and drying at 30°C. The morphological structure, miscibility, thermal stability, mechanical properies, and swelling capacity of the blend films were studied by infrared (IR), X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron micrograph (SEM), and measurements of the mechanical properties and swelling properties. The results demonstrated that there was strong interaction and good miscibility between CS and CMKGM resulted from intermolecular hydrogen bonding and electrostatic force. The mechanical properties in dry state and wet state, thermostability, and water swelling properties of the blend films were obviously improved. The best values of the tensile strength in the dry and wet state achieved 89 MPa and 49 MPa, respectively, when the CMKGM content was 30%(weight). The CS/ CMKGM blend films provided promising biomedical applications.

关键词： Key words chitosan carboxymethylated konjac glucomannan blend films structure characterization

A quasi-human algorithm for solving the three-dimensional rectangular packing problem

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science china(Information sciences) 2010年第12期53卷 2389-2398页

作者： HE Kun & HUANG WenQi school of Computer science and technology, Huazhong university of science and technology, wuhan 430074, china 1. school of Computer science and technology Huazhong University of Science and Technology Wuhan 430074 China

Based on the concept of maximal rectangular space that can be filled at current time and the siege warfare tactics, we make several critical improvements on the quasi-human caving-degree approach to get a stronger algorithm ICDA for a classical NP hard problem: the three-dimensional rectangular packing problem. Within similar computing time, the new algorithm gained an average volume utilization of 90.92% on the natural and difficult 100 benchmarks, called BR15, where items to be packed are almost different in size. Compared with current best record just reported in the literature in 2010, our result makes an improvement by 0.54%.

关键词： NP hard three-dimensional packing quasi-human action space caving degree

XPS Analysis of Ni and Oxygen in Single-Sintered SrTiO_3 Multifunction Ceramic

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Journal of Materials science & technology 2001年第5期17卷 535-537页

作者： Qing XU, Wen CHEN and Runzhang YUAN State Key Laboratory of Advanced technology for Materials Synthesis and Processing, wuhan university of technology, wuhan 430070, china wuhan Univ Technol State Key Lab Adv Technol Mat Synth & Proc Wuhan 430070 Peoples R China

XPS analyses have been performed to investigate the chemical conditions of Ni and oxygen on grain surfaces in single-sintered SrTiO3 capacitor-varistor ceramic doped with Nb2O5 and NiO. It is ascertained that Ni is in form of Ni2+ ions, which substitute for Ti4+ ions on grain surfaces during the oxidizing annealing. Moreover, it is confirmed that three kinds of chemically adsorbed oxygen such as O2-, O- and O-2(-) are formed on grain surfaces. It is proposed that these behaviors contribute greatly to the generation of multiple types of grain boundary acceptor states in the ceramic.

关键词： XPS Analysis of Ni and Oxygen in Single-Sintered SrTiO3 Multifunction Ceramic Ni

Structure and Infrared Radiation Properties of Substituted Cordierites

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Journal of wuhan university of technology(Materials science) 2006年第4期21卷 68-70页

作者：徐庆 school of Materials science and Engineering Wuhan University of TechnologyWuhan 430070China

Zn^2＋ - or Ti^4＋ -substituted cordierites with the nominal compositions of Mg1 .6 Zn0.4 Al4 Si5 O18 and Mg1.8 Ti0.2 Al4.4 Si4.6 O18 respectively, were prepared by a conventional solid state reaction method. The structure of the substituted eordierites was characterized by X- ray diffraction （ XRD ）, infrared （ 1R ） spectroscopy and 29 Si magic angle spinning （ MAS ） nuclear magnetic resonance （ NMR ）. The infoared radiation properties were investigated in the bands within 2.5-25μm. Compared with the na-substituted cordierite composition （ Mg2 Al4 Si5 O18 ）, Zn^2＋ - or Ti^4＋ -substituted cordierites show superior infrared properties. XRD and IR results confirm the formation of hexagonal a-eordierite as the main eo＇stal phase for the substituted cordierites. 29 Si MAS NMR result indicates that Zn^2＋ or Ti^4＋ Substitutions for partial Mg^2＋ of a-eordierite promoted the ordering of the distribution oral and Si atoms in T1 （ tetrahedra connecting six-raembered rings together with [ MgO6] octahedra ） and T2 （ tetraheda forming six-reentered rings） tetrahedral sites. This resulted in a lattice deformation and increased the anharmonicity of polarization vibration, which is responsible for the improvement of infrared radiation properties of the substituted eordierites.

关键词： α-eordierite infrared radiation properties substitution 29 Si MAS NMR

Dynamic Mechanical and Thermal Properties of Cross-linked Polystyrene/Glass Fiber Composites

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Journal of wuhan university of technology(Materials science) 2010年第5期25卷 780-784页

作者：朱泉峣陈文 school of Materials science and Engineering Wuhan University of Technology State Key Laboratory of Advanced technology for Materials Synthesis and Processing Wuhan University of Technology

Cross-linked polystyrene/glass fiber composites were fabricated using cross-linked polystyrene （CLPS） as matrix and E-glass fiber as the reinforcement. Surfaces of E-glass fibers were modified by vinyl triethoxysilane （VTES）, vinyl trimethoxysilane （VTMS） and γ-methacryloylpropyl trimethoxysilane （MPS）. The treated glass fibers were analyzed by fourier transform infrared spectroscopy （FTIR）. Dynamic mechanical thermal analysis （DMTA） and thermo-gravimetric analysis （TGA） were employed to investigate the effect of glass fibers surface modification on viscoelastic behavior and thermal properties. The morphology of fracture surfaces of various composites was observed by scanning electron microscopy （SEM）. The results revealed that these coupling agents were connected to the surfaces of the fibers by chemical bonding. Dynamic mechanical properties as well as thermal stability of the composites were improved considerablely, but to varying degrees depending on the fiber modification. The diversities of improvement of properties were attributed to the different interfacial adhesion between CLPS matrix and the glass fibers.

关键词： polymer-matrix composite cross-linked polystyrene (CLPS) fiber/matrix bond dynamic mechanical thermal analysis.

Reduction of Residual Stress in Low Alloy Steel with Magnetic Treatment in Different Directions

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Journal of wuhan university of technology(Materials science) 2009年第6期24卷 857-862页

作者：宋燕利华林 school of Materials science and Engineering Wuhan University of Technology

The behavior that different magnetic treatment directions induce various amounts of welding residual stress reductions in low alloy steel was studied. Reductions of 26%-28% in the longitudinal stress σ x were obtained when low frequency alternating magnetic treatment was applied perpendicularly to the welding bead, whereas reductions of 20%-21% in σ x were measured by using the same treatment parameters except that the field direction was applied parallel to the bead. It is proposed that different extent of stress reductions caused by the above two treatment directions is attributed primarily to the alteration of the energy absorbed by domains from the external magnetic field, which part of energy can arouse plastic deformation in microstructures by the motion of domain walls.

关键词： magnetic treatment direction magnetic domain residual stress spontaneous magnetization micro plastic deformation