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Multiwalled Carbon Nanotubes Reinforced Alumina Composites

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Journal of wuhan university of Technology(materials {3.) 2011年第6期26卷 1171-1173页

作者：张金咏 state key laboratory of {3. Technology for materials synthesis and processing Wuhan University of Technology

1wt% multiwalled carbon nanotube （MWNTs） reinforced alumina composites was sintered to full density by spark plasma sintering. And pure alumina and graphite/alumina composites were also prepared by the same way for comparison. Indentation and single edge V-notched beam （SEVNB） toughness were measured respectively. The experimental results show that MWNTs could not improve toughness of alumina too much as that once expected. And SEVNB toughness was more valid than indentation toughness.

关键词： MWNT alumina toughness

Influence of Fe/Ni/Al Additive on the Sintering Behaviors of TiB_2 Cermets

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Journal of wuhan university of Technology(materials {3.) 2009年第6期24卷 879-882页

作者：陈华张金咏 state key laboratory of {3. Technology for materials synthesis and processing Wuhan university of Technology

Fe-Ni-Al mixtures as hot-pressing sintering additive to Titanium diboride （TiB2） were studied. It is found that liquid alloy formed under high temperature hardly has effects on the densification behaviors of TiB2-independent. Fe-Ni-Al additive just works as filler between TiB2 particles and does not change the TiB2-independent sintering behaviors. Pressing mode has a great effect on the liquid flowing between TiB2 particles. Multiple-steps pressing mode will give more time and space for the liquid flowing and improve the relative density of TiB2-Fe-Ni-Al cermet.

关键词： hot-pressing liquid content pressing modes

Manufacture of the Ultrafine Grain WC/Co Cemented Carbides by Combined Sintering processing

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International Journal of Minerals,Metallurgy and materials 1999年第3期13卷 208-213页

作者： Binghai Liu Yue Zhang Shixi Ouyang Qikai Li(Institute of Technical Physics and Chemistry, East china university of science and Technology , Shanghai 20023., china)(Material science and Engineering School. university of science and Technology Beijing, Beijing 100083. china)(state key laboratory for synthesis and processing of {13. materials. wuhan university of science and Technology, wuhan 43.070, china,) E china Univ Sci & Technol Inst Tech Phys & Chem Shanghai 200237 Peoples R China Univ Sci & Technol Beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China wuhan Univ Sci & Technol State Key Lab Synth & Proc Adv Mat Wuhan 430070 Peoples R China

A new kind of sintering process, combined sintering process. i.e. vacuum sintering plus hot isolate pressure sintering (HIP), was introduced for producing ultrafine WC-10% Co (mass fraction. so as the follows) cemented carbides. The effects of some processing parameters on the microstructure and mechanical properties of the obtained cemented carbides were studied. The results show that the rapid shrinkage and the pronounced densification of tile cemented carbides took place during the vacuum sintering stage, which is intinaately correlated with the local liquid sintering occurred during this earl} sintering stage for the high surface activity of ultrafine WC-Co powder. The way of high pressure imposing. isothermal treatment cycle during *** sintering and HIP sintering stage directly influence the densitication of compacts and the mechanical properties of the produced WC-10%Co cemented carbides.

关键词： ultrafine WC-Co cemented carbides vacuum sintering HIP sintering

A Modified Integrated Model of the Internal Structure of Chinese Cultured Pearls

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Journal of wuhan university of Technology(materials {3.) 2011年第3期26卷 510-513页

作者：马红艳 key laboratory of Nonferrous Metals and New Material processing Technology Ministry of EducationCollege of Materials Science and EngineeringGuangxi University

Optical and micro-infrared microscope were used to observe the internal structure and mineral composition of high and low quality Chinese seawater and freshwater cultured *** clearly reveal that aragonite and calcite are found in seawater cultured pearls,but vaterite is not *** contrast,vaterite and aragonite are found in freshwater cultured pearls,but calcite is not *** on our analysis and observations of the internal structure of high and low quality cultured pearls,a modified integrated model of the internal structure of Chinese cultured pearls was *** revisions to the previous model focus on significant differences within the prismatic layer of Chinese cultured pearls.

关键词： cultured pearls aragonite vaterite calcite integrated model

Electronic Structures and Bonding Properties of Ti_2AlC and Ti_3.lC_2

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Journal of wuhan university of Technology(materials {3.) 2007年第1期22卷 27-30页

作者：闵新民 Department of Applied Chemistry School of Science Wuhan University of Technology state key laboratory of {3. Technology for materials synthesis and processing Wuhan University of Technology Wuhan 430070 China

The relation among electronic structure, chemical bond and property of Ti2AlC, Ti3.lC2 and doping Si into Ti2AlC was studied by density function and the discrete variation （DFT-DVM） method. After adding Si into Ti2AlC, the interaction between Si and Ti is weaker than that between Al and Ti, and the strengths of ionic and covalent bonds decrease both. The ionic and covalent bonds in Ti3.lC2, especially in Ti-Al, are stronger than those in Ti2AlC. Therefore, in synthesis of Ti2AlC, the addition of Si enhances the Ti3.lC2 content instead of Ti2AlC. The density of state （DOS） shows that there is mixed conductor characteristic in Ti2AlC and Ti3.lC2. The DOS of Ti3.lC2 is much like that of Ti2AlC. Ti2SiAl1-xC has more obvious tendency to form a semiconductor than Ti2AlC, which is seen from the obvious difference of partial DOS between Si and Al 3.7.

关键词： Ti2AlC Ti3.iC2 doping electronic structure chemical bond

Microstructure and Temperature Distribution in ZnAl_2O_4 Sintered Body by Pulse Electric Current

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Journal of materials science & Technology 2003年第6期19卷 526-528页

作者： Dongming ZHANG, Zhengyi FU and Jingkun GUOstate key Lab. of advanced Technology for {3. synthesis and processing, wuhan university of Technology, wuhan 43.070, china wuhan Univ Technol State Key Lab Adv Technol Mat Synth & Proc Wuhan 430070 Peoples R China

Microstructure of reaction sintering of ZnAl2O4 at 1500℃ by hot-pressing(HP) and pulse electric current was investigated. The results indicated that the existed cracks in sintered body were caused by structure mismatch. It is the evidence that periodical temperature field existed during pulse electric current sintering of nonconductive materials. The distance between high temperature areas was related to die diameter.

关键词： Pulse electric current sintering Reaction sintering ZnAl2O4,Microstructure Temperature distribution.

The Properties of Solution Precursor Plasma Spray Nanostructured Thermal Barrier Coatings

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Journal of wuhan university of Technology(materials {3.) 2010年第6期25卷 924-928页

作者：闵捷 state key laboratory of {3. Technology for materials synthesis and processing Wuhan University of Technology

About 3.0 μm thickness uniform thermal barrier coatings （TBCs） were deposited on the 1Cr18Ni9Ti samples by solution precursor plasma spray （SPPS）.The analysis methods,such as TEM,SEM,and XRD were used to characterize the coatings in the aspects of microstructure and phase *** samples were quenched from 1121 ℃ to room temperature by forced-air to measure the thermal cycling *** density were measured by means of water *** experimental results show that grain size of the SPPS TBCs is about 3. nm with desired tetragonal phase ZrO2,and the SPPS TBCs（with 16% porosity） consist of arcuate pores,gelatin and melted *** hardness of the coatings is HR45Y3..5 and bond strength between coatings and substrates is 24.2 *** thermal shock test show the coatings have a average life of 500 cycles which is about 2.5 times than that of conventional air plasma spray （APS） TBCs.

关键词： SPPS TBCs nanostructure properties

Electronic Structure and Thermoelectric Properties of Na and Ni-doped Ca_3.o_2O_6

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Journal of wuhan university of Technology(materials {3.) 2006年第3期21卷 94-96页

作者：闵新民 Department of Applied Chemistry Wuhan University of Technology Wuhan 430070 ChinaState Key Laboratory of Advanced Technology for Materials Synthesis and ProcessingWuhan University of Technology Wuhan 430070China

The electronic structures of Ca3.o2O6, Na and Ni doped models were studied by the quantum chemical software of Cambride Serial Total Energy Package （CASTEP） that is based on deusity function theory （DFT） and psendo-potential. The electronic conductivity, seebeck coefficient, thermal conduetivity and figure of merit （Z） were computed. The energy band structure reveals the form of the impurity levels due to the substitutional imapurity in semiconductors. Na-doped model stunts the character of p-type semiconductor, but Xi-doped model is n-type semiconductor. The calculation results show that the electric conduetirity of the doped model is higher than that of the non-doped model, while the Seebeck coefficient and thermal conductivity of the doped model are lower than those of the non-doped one. Because of the great increase of the electric conductivity, Z of Na- doped model is enhanced and thermoelectric properties are improved. On the other hand, as the large decline of Seebeck coefficient, Z of Ni-doped model is less than that of the non-doped model.

关键词： cobalt oxide substitutional impurity quantum chemical calculation electronic structure thermoelectric property

Effect of Tin on the Reaction synthesis of Ternary Carbide Ti_3.lC_2

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Journal of wuhan university of Technology(materials {3.) 2009年第2期24卷 283-286页

作者：周卫兵 School of materials science and Engineering Wuhan University of Technology

The effect of tin on synthesis of Ti3.lC2 by spark plasma sintering （SPS） from TiC/Ti/Al powders was investigated. X-ray diffraction （XRD） and scanning electron microscopy （SEM） were used for phase identification and microstructure evaluation. The experimental results show that addition of tin can considerably accelerate the synthesis reaction of Ti3.lC2 and fully dense, essentially single-phase polycrystalline Ti3.lC2 could be successfully obtained by sintering 2TiC/1Ti/1Al/0.2Sn powders at 1200-1250 ℃ under a pressure of 3. MPa. SEM images show that Ti3.lC2 samples in about 2-5 μm thick and 10-25μm long platelets can be obtained. The fracture toughness and flexural strength of Ti3.lC2 were 6.5±0.2 MPa·m^1/2 and 560±10 MPa, respectively.

关键词： titanium aluminum carbide spark sintering technique synthesis