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Sol-gel Preparation and Infrared Radiation Property of Boron-substituted Cordierite Glass-ceramics

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Journal of materials science & Technology 2010年第5期26卷 445-448页

作者： Shuming Wang and Fenghua Kuang School of materials science and engineering,university of science & Technology Beijing,Beijing 100083,china School of materials science and engineering University of Science & Technology Beijing Beijing 100083 China

Boron for aluminum substitution in the cordierite structure has been examined by sol-gel preparation of different samples along the compositional junction Mg2Al4-xBxSi5O18 with x=0,0.5,1,*** increasing the x value from 0 to 1.5 the crystallization behavior changed *** amount B2O3 doping can promote the sintering of amorphous cordierite gel,effectively restrain the precipitation of μ-cordierite and enhance the crystallization of α-*** substitution of B3＋ for Al3＋ in cordierite crystal structure can effectively improve the near-infrared spectral emissivity of this cordierite based glass-ceramics.

关键词： Sol-gel Glass-ceramics Infrared radiation B3+ substitution Solid solution

Dominant point detecting based non-uniform B-spline approximation for grain contour

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science china(Technological sciences) 2007年第1期50卷 90-96页

作者： ZHAO XiuYang1, YIN YanSheng1,2 & YANG Bo3 1 Shandong Key Laboratory of engineering Ceramics, Shandong university, Jinan 250061, china 2 School of materials, Ocean university of china, Qingdao 266003, china 3 State Key Laboratory of Advanced Technology for materials Synthesis and Processing, wuhan university of science and Technology, wuhan 430070, china Shandong Key Laboratory of engineering Ceramics Shandong UniversityJinan 250061China School of materials Ocean University of ChinaQingdao 266003China State Key Laboratory of Advanced Technology for materials Synthesis and Processing Wuhan Univers

Three-dimension reconstruction from serial sections has been used in the last decade to obtain information concerning three-dimensional microstructural ge-ometry. One of the crucial steps of three-dimension reconstruction is getting compact and fairing grain contours. Based on the achievement of closed raw con-tours of ceramic composite grains by using wavelet and level set, an adaptive method is adopted for the polygonal approximation of the digitized raw contours. Instead of setting a fixed length of support region in advance, the novel method computes the suitable length of support region for each point to find the best es-timated curvature. The dominant points are identified as the points with local maximum estimated curvatures. Periodic closed B-spline approximation is used to find the most compact B-spline grain boundary contours within the given tolerance. A flexible distance selection approach is adopted to obtain the common knot vector of serial contours consisting of less knots that contain enough degrees of freedom to guarantee the existence of a B-spline curve interpolating each contour. Finally, a B-spline surface interpolating the serial contours is generated via B-spline surface skinning.

关键词： composite B-spline dominant points control points grain contour

Piezoresistivity of Carbon Fiber Graphite Cement-based Composites with CCCW

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Journal of wuhan university of Technology(materials science) 2011年第2期26卷 340-344页

作者：范晓明 School of materials science and engineering Wuhan University of Technology

The electrical conductivity and piezoresistivity of carbon fiber graphite cement-matrix composites（CFGCC） with carbon fiber content（1% by the weight of cement）,graphite powder contents （0%-50% by the weight of cement） and CCCW（cementitious capillary crystalline waterproofing materials,4% by the weight of cement） were *** experimental results showed that the relationship between the resistivity of CFGCC and the concentration of graphite powders had typical features of percolation *** percolation threshold was about 20%.A clear piezoresistive effect was observed in CFGCC with 1wt% of carbon fibers,20wt% or 30wt% of graphite powders under uniaxial compressive tests,indicating that this type of smart composites was a promising candidate for strain *** measured gage factor （defined as the fractional change in resistance per unit strain） of CFGCC with graphite content of 20wt% and 30wt% were 37 and 22,*** the addition of CCCW,the mechanical properties of CFGCC were improved,which benefited CFGCC piezoresistivity of stability.

关键词： carbon fiber graphite cement-based composites cementitious capillary crystalline waterproofing materials electrical resistivity piezoresistivity

STUDY ON THE MISCIBILITY OF DYNAMICALLY VULCANIZED EPDM/PP BLEND BY POSITRON ANNIHILATION SPECTROSCOPY

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Chinese Journal of Polymer science 2000年第2期18卷 123-128页

作者： Tao Jiang Xue-liang Jiang Shi-yuan Cheng Yi-qun Dai Shao-jie Wang Bo Wang faculty of Chemistry & Material, hubei university, wuhan 4.0062, china Department of Physics, wuhan university, wuhan 430072, china 湖北大学湖北武汉武汉大学湖北武汉

Positron annihilation spectroscopy (PAS) was utilized to investigate the relationship between the free-volume hole properties and miscibility of dynamically vulcanized EPDM/PP blend. The results showed that the noncrystalline region of PP and EPDM in the blend was partially miscible and the miscibility of the blend became worse when the weight percent of EPDM was <50%. This was also demonstrated by DMTA and mechanical properties of the blends with various compositions.

关键词： EPDM PP dynamic vulcanization miscibility PAS

Structure and Properties of Mg-doped SrBi_4Ti_4O_(15) Bi-layered Compounds

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Journal of wuhan university of Technology(materials science) 2008年第5期23卷 675-677页

作者：郝华 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

The structure and properties of Mg-doped SrBi4Ti4O15（SBT） were dicussed. Mg substitution into SBT had two possibilities states with the dopant amount variety. Mg cation substituted mostly into Sr^2＋ and the amount proportion was 68.11%.Mg ion will substitute into Ti ion site in perovskite layer when the doping amount increases. Polarization increases sharply when x=0.1 and then decreases becauses of the domain pinning. The Curie temperature of Mg-doped SBT is about 300 ℃ and there is a broad diffuse phase transition near Tc with a flat peak near the Ta of SBT.

关键词： Mg-doped bismuth layer structure ferroelectrics ferroelectric properties

SOME THERMODYNAMIC PROPERTIES OF Pd-In ALLOYS

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Acta Metallurgica Sinica(English Letters) 1997年第4期10卷 311-317页

作者： YL. Chen(Department of materials science and engineering, Zhejiang university, Hangzhou 310027, china) Zhejiang Univ Hangzhou China

Some thermodynamic parnmeters of Pd-In alloys with 2 to 70 at. H indium have been determined in the temperuture range 800 to 1000℃ from e.m.f measurements ongalvanic cells with an onsen-cotzducting solid electrolyte. Heats of tnising calculated hem the activities are in excellent agreement with calorimetric data. The relative partial excess hee enengy of indiurn assumes unnsually larpe negative values ap to-174kJ/mol for Pd-rich alloys. Two efficts are discussed to account for the non-idealproperties: The rise Of Fermi enerpy as the valence electron8 of indium enter the 4dand 5sP bands of the alloy and the lattice distortion brought about by the differentmolar volumes of the cofnponents. The rise of the Fermi enerpy, as determlned fromthe activity data, indicates a strict adherence of the alloys to the rigid band model.

关键词： galvanic cell activity data Fermi energy,lattice distortion rigid band model

Dynamic Mechanical Behaviour of Ultra-high Performance Fiber Reinforced Concretes

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Journal of wuhan university of Technology(materials science) 2008年第6期23卷 938-945页

作者：赖建中 Department of materials science & engineering Nanjing University of Science & Technology

Ultra-high performance fiber reinforced concretes （UHPFRC） were prepared by replacing 60% of cement with ultra-fine industrial waste powder. The dynamic mechanical behaviour of UHPFRC with different fiber volume fraction was researched on repeated compressive impact in four kinds of impact modes through split Hopkinson pressure bar （SHPB）. The experimental results show that the peak stress and elastic modulus decrease and the strain rate and peak strain increase gradually with the increasing of impact times. The initial material damage increases and the peak stress of the specimen decreases from the second impact with the increasing of the initial incident wave. Standard strength on repeated impact is defined to compare the ability of resistance against repeated impact among different materials. The rate of reduction of standard strength is decreased by fiber reinforcement under repeated impact. The material damage is reduced and the ability of repeated impact resistance of UHPFRC is improved with the increasing of fiber volume fraction.

关键词： ultra-high performance fiber reinforced concretes split Hopkinson pressurebar dynamic repeated impact

Microstructure and thermal stability behavior of a rapidly solidified Al-Ti-Fe-Cr alloy

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Rare Metals 2002年第3期21卷 207-212页

作者： CHEN Yiqing, CAO Qingping, and SU YongSchool of materials science and engineering, Hefei university of Technology, Hefei 230009, china School of materials science and engineering Hefei University of Technology Hefei 230009

A rapidly solidified Al-2.5Ti-2.5Fe-2.5Cr (mass fraction in percent) alloywas prepared by melt spinning. As-quenched and as-annealed microstructures were studied by X-raydiffractometry (XRD), transmission electron microscopy (TEM), high-resolution transmission electronmicroscopy (HREM) and energy dispersive spectrum (EDS) analysis. The microhardness of the alloy atdifferent annealing temperatures was measured. The results obtained indicate that the microhardnessof the rapidly solidified Al-2.5Ti-2.5Fe-2.5Cr alloy does not vary with different annealingtemperatures. The as-quenched microstructure of the alloy includes two kinds of dispersed primaryphases: Al_3Ti and Al_(13)(Cr, Fe)_2. After annealing at 400 deg C for 10 h, the stable phaseAl_(13)Fe_4 appears in the microstructure.

关键词： rapidly solidified Al-Ti-Fe-Cr alloy microhardness as-quenchedmicrostructure as-annealed microstructure

High-temperature oxidation behavior of Al_2O_3/TiAl matrix composite in air

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science china(Technological sciences) 2009年第5期52卷 1273-1282页

作者： AI TaoTao1,WANG Fen2 & FENG XiaoMing1 1 Department of materials science and engineering,Shaanxi university of Technology,Hanzhong 723003,china 2 School of materials science and engineering,Shaanxi university of science and Technology,Xi’an 710021,china Department of materials science and engineering Shaanxi University of Technology School of materials science and engineering Shaanxi University of Science and Technology

The oxidation behavior of Al2O3/TiAl in situ composites fabricated by hot-pressing technology was in-vestigated at 900℃ in static *** results indicate that the mass gains of the composites samples decrease gradually with increasing Nb2O5 content and the inert Al2O3 dispersoids effectively increase the oxidation resistance of the *** higher the Al2O3 dispersoids content,the more pro-nounced the *** primary oxidation precesses obey approximately the linear laws,and the cyclic oxidation precesses follow the parabolic *** oxidized sample containing Ti2AlN and TiAl phases in the scales exhibits excellent oxidation *** oxide scale formed after exposure at 900 ℃ for 120 h is multiple-layered,consisting mainly of an outer TiO2 layer,an intermediate Al2O3 layer,and an inner TiO2+Al2O3 mixed *** the outer layer to the inner layer,TiO2+Al2O3 mixed layer presents the transit of Al-rich oxide to Ti-rich oxide mixed *** the substrate,cross-section micrograph shows a relatively loose layer,and micro-and macro-pores remain on this layer,which is a transition layer and transferres from Al2O3+TiO2 scale to *** thickness of oxide layer is about 20 μ*** is also found that continuous protective alumina scales can not be observed on the surface of oxida-tion *** ions diffuse outwardly to form the outer TiO2 layer,while oxygen ions transport inwardly to form the inner TiO2+Al2O3 mixed *** long-time intensive oxidation exposure,the internal Al2O3 scale has a good adhesiveness with the outer TiO2 *** obvious spallation of the oxide scales *** increased oxidation resistance by the presence of in situ Al2O3 particulates is at-tributed to the enhanced alumina-forming tendency and thin and dense scale ***2O3 particu-lates enhance the potential barrier of Ti ions from M/MO interface to O/MO interface,thereby the TiO2 growth rate decreases,which is also beneficial to improve the oxidation resistance.

关键词： Al2O3/TiAl matrix composite oxidation resistance high temperature