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Preparation and Characterization of High Quality Diamond Films by DC ArcPlasma Jet CVD Method

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International Journal of Minerals,Metallurgy and materials 1999年第4期13卷 281-284页

作者： Guofang Zhong Fazheng shen Fanxiu Lu Weizhong Tang(material science and {3. school, University of science and technology’ beijing, beijing 100083. china) material science and engineering {3. University of Science and Technology Beijing Beijing 100083 China

Under optimal conditions free-standing high quality diamond films were prepared by DC arc plasma jet CVD method at a growth rate of 7-10 Pm/h. Surface and cross section morphologies of the diamond films were observed by SEM. Raman spectrometer wasused to characterize the quality of diamond films. The IR transmittivity measured by IR spectrometer is close to the theoretical value ofabout 71% in the far infrared band. The thermal conductivity measured by photothermal deflection exceeds 18 W/cm' K. is thepreferential growth orientation of the films detected by X-ray diffractometer. As s result, the extremely high temperature of DC arc plasma jet can produce supersaturated atomic hydrogen, which played an important role in the process for the deposition of high quality diamond films.

关键词： D.C. plasma jet CVD diamond films, free-standing characterization

Characterization of the negative thermal expansion material Zr_(1-x)Hf_xW_2O_8

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Rare Metals 2003年第2期22卷 107-111页

作者： shenRong WANGCong WANGTianmin DONGCheng CHENHong LIANGJingkui schoolofMatgfialsandMetallurgicalengineering KunmingUniversityofScienceandTechnologyKunming650093China CenterofmaterialPhysicsandChemistry SchoolofSciencesBeijingUniversityofAeronauticsandAstronauticsBeijing100083China InstituteofPhysics ChineseAcademyofScienceBeijing100080China

The oxide ZrW_2O_8 displays unusual property of isotropic negative thermalexpansion in a large wide temperature range, which makes it have a number of important potentialapplications. The cubic Zr_(1-x)Hf_xW_2O_8 (x velence 0,0.3. 0.5, 0.7, and 1.0) were synthesized bystandard solid state reaction technique. The high and low temperature X-ray diffraction analysisindicate that the substitution of the Hf^(4+) for Zr^(4+) only leads to reducing the latticeconstants, and the changes of negative thermal expansion coefficients are not obvious. The linearexpansion coefficients of Zr_(1-x)Hf_xW_2O_8 (x velence 0,0.3. 0.5, 0.7, and 1.0) are about -6 X 10^(-6) K^(-1) in the temperature range of 298 to 973.K, while that of Zr_(0.5)Hf_(0.5)W_2O_8 is -9.6X 10^(-6) K_(-1) from 83.to 298 K. The phase transition temperatures from alpha-ZrW_2O_8 tobeta-ZrW_2O_8 structure were also determined by X-ray diffraction method. Thermogravimetric analysis(TGA) exhibits that Zr_(1-x)Hf_xW_2O_8 is not hygroscopic in air.

关键词： inorganic non-metallic materials negative thermal expansion X-raydiffraction Zr_(1-x)Hf_xW_2O_8

The Crack of Harden Cement Paste Observed with Multi-technique

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Journal of Wuhan University of technology(materials science) 2010年第6期25卷 1057-1060页

作者：沈卫国 Key Laboratory for Silicate materials science and engineering of Ministry of Education Wuhan University of Techoology school of materials science and {3. Wuhan University of Technology

The shrinkage of the cement paste with low water-cement ratio at different relative humidity was observed and analyzed with ESEM and deformation map *** crack morphology was observed with different magnification with SEM and FESEM,and the formation of the crack was observed with AFM between two C-S-H nano *** observation by multi technique at multi scale indicated that the shrinkage was increase with the decrease of the humidity due to the increase of the pressure of the capillary pressure,the morphology of the crack in smaller scale was similar to that in the bigger scale,the smaller crack distributed in the latticework of the bigger ones,and the crack propagated along the gap between two nano particles of C-S-H with weaker bonding.

关键词： crack cement paste shrinkage muli technique multi-scale

Metal Fe,Ni and Fe-Ni Fine Fibers Derived from the Organic Gel-Thermal Reduction Process

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Journal of Wuhan University of technology(materials science) 2007年第4期22卷 577-581页

作者：沈湘黔 school of material-science and {3. Jiangsu University

The organic gel-thermal reduction process was successfully used for the preparation of magnetic metal Ni, Fe, Fe-Ni fine fibers from raw materials of citric acid or lactic acid and metal salts. Ni, Fe and Fe-Ni fine fibers synthesized were featured with diameters of around 1 μm and lengths of as long as 2 m for Ni fibers, 0.5 m for iron fibers, 1 m for Fe-Ni fibers. The structure, thermal decomposition process and morphologies of the gel precursors and fibers derived from thermal reduction of these gel precursors were characterized by FTIR, XRD,TG/DSC and SEM, respectively. The gel spinnability largely depends on molecular structures of metal-carboxylate complexes formed in the gel. It is reasoned that these gels consist of linear-type structural molecules [（C6H6O7）Ni]n or [（C6H5O7）2Ni3. for the nickel citrate gel, [（C3.5O3.3.e] for the ferric lactate gel, [（C6H5O7）5（NiFe）3. for the iron-nickel citrate gel respectively and the gels obtain showed a good spinning performance.

关键词： magnetic metal fiber organic-gel thermal reduction spinning performance

Investigation of Ce/BEA as a passive NO_(x)adsorber:*** aging deactivation mechanism

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Journal of Rare Earths 2024年第8期42卷 1524-1530,I0004页

作者： Yiying Ding Minghui Yu Xiaojie Yu Meiqing shen Jianqiang Wang Jun Wang Gurong shen school of Chemical engineering and technology Tianjin UniversityTianjin300350China school of materials science and {3. Tianjin UniversityTianjin300350China National Rare Earth Catalysis Research Institute Dongying257000China

Ce/BEA has the potential to be applied as a novel passive NO_(x)absorber(PNA)in the after-treatment of vehicles due to its considerable NO_(x)storage ***,as a vehicle exhaust after-treatment material,it must withstand the test of long-term hydrothermal *** work examined the deactivation mechanism of Ce/BEA during hydrothermal aging.3.0 wt%Ce/BEA was prepared using the ionexchange method,and then subjected to hydrothermal treatment at 650℃with 10%H_(2)O for 1-12 h to obtain samples with different aging *** comparison,the H-BEA support was aged under the same ***-Emmett-Teller(BET)method,X-ray diffraction(XRD),NH_(3.temperature programmed reduction(NH_(3.-TPD),^(27)Al MAS nuclear magnetic resonance(^(27)Al MAS NMR),H_(2)temperature programmed reduction(H_(2)-TPR),and high resolution-transmission electron microscopy(HR-TEM)were performed to characterize the changes in PNA performance,structure,Ce species,and *** HR-TEM and H_(2)-TPR results show that CeO_(x)particles appear after hydrothermal aging,which results from the detachment and aggregation of active Ce *** on the^(27)Al MAS NMR results,we conclude that BEA zeolite dealumination leads to the loss of acidic sites and the transformation of active Ce species on the acidic sites into the less active CeO_(x).This is the primary reason for the hydrothermal aging deactivation of Ce/BEA.

关键词： Passive NO_(x)adsorber Ce/BEA Hydrothermal aging CeO_(x) Dealumination Rare earths

Influence of Molecular Weight of PEO on Performance of Quasi-solid-state Dye-sensitized Solar Cells

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Journal of Wuhan University of technology(materials science) 2010年第2期25卷 218-222页

作者：沈小林 school of materials science & {3. Xi’an Jiaotong University

Quasi-solid-state dye-sensitized solar cells （DSCs） were prepared using gel electrolyte gelated by poly（ethylene-oxide）（PEO） with different molecular weight. With the increase in PEO molecular weight, the short circuit current densities （Jsc） increase significantly, which is related to the increase in I - diffusion due to the increase in free volume of gel electrolyte. However, only a slight increase in open voltage （Voc） is observed, which is explained by the decrease in dark current arising from the reduction of triiodide （I3.-） by conduction band electrons.

关键词： dye-sensitized solar cell poly(ethylene oxide) gel electrolyte molecular weight

Investigation of Ce/BEA as a passive NO_(x)adsorber:*** occurrences of cerium and adsorption behavior

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Journal of Rare Earths 2024年第7期42卷 1265-1271,I0003页

作者： Minghui Yu Yiying Ding Xiaojie Yu Siwei Yan Meiqing shen Jianqiang Wang Jun Wang Gurong shen school of materials science and {3. Tianjin UniversityTianjin300350China school of Chemical engineering and technology Tianjin UniversityTianjin300350China National Rare Earth Catalysis Research Institute Dongying257000China

Ce/BEA has great potential as a passive NO_(x)absorber(PNA)to reduce the NO_(x)emissions during the cold start phase especially in diesel engine for its high resistance to CO and suitable NO_(x)desorption temperature ***,as a novel material,its physical and chemical properties still remain *** this work,Ce/BEA was synthesized by ion-exchange method to identify the active species in NO_(x)adsorption,compared with aggregated Ce species in Ce/SiAlO_(x) prepared by impregnation method.X-ray diffraction(XRD),high resolution-transmission electron microscopy(HR-TEM)and aberration-corrected-scanning transmission electron microscopy(AC-STEM)were performed to confirm the isolated single atom formation of Ce species in Ce/***-vis diffraction reflection spectra(DRS)and X-ray photoelectron spectroscopy(XPS)were conducted to find the difference of chemical environment between the isolated Ce species and aggregated *** performance evaluation and temperature programmed reduction of hydrogen(H_(2)-TPR)results show the high NO_(x)storage capacity and active oxygen species quantity in Ce/*** is also found that the main NO_(x)adsorption species are Ce^(4+)-O^(∗)rather than Ce^(3.).NO_(x)-diffuse reflectance infrared Fourier transform spectroscopy(NO_(x)-DRIFTS)confirms that the bidentate nitrite species are the critical NO_(x)adsorption intermediates and the conception of NO_(x)adsorption and desorption processes is proposed.

关键词： Passive NO_(x)absorber Ce/BEA Isolated Ce species Rare earths

Arc erosion behavior of a nanocomposite W-Cu electrical contact material

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Rare Metals 2006年第1期25卷 37-42页

作者： CHEN Wenge KANG Zhanying shen Hongfang DING Bingjun school of materials science and {3. Xi＇an University of Technology Xi＇an 710048 China Department of materials Physics Xi＇an Jiaotong University Xi＇an 710049 China

The erosion behavior of a nanocomposite W-Cu material under arc breakdown was investigated. The arc erosion rates of the material were determined, and the eroded surfaces and arc erosion mechanisms were studied by scanning eleclion microscopy. It is concluded that the nanocomposite W-Cu electrical contact material shows a characteristic of spreading arcs. The arc breakdown of a commercially used W-Cu alloy was limited in a few areas, and its average arc erosion rate is twice as large as that of the former. Furthermore, it is also proved that the arc extinction ability and arc stability of the nanocomposite W-Cu material are excellent, and melting is the major failure modality in the make-and-break operation of arcs.

关键词： arc erosion W-Cu alloy contact materials nanocomposite

Kinematic Study on Motoman HP6 Arc Welding Robot Based on Unigraphics

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Transactions of Tianjin University 2011年第3期17卷 199-202页

作者：冯胜强胡绳荪申俊琦 Tianjin Key Laboratory of Advanced Joining technology School of Material Science and Engineering Tianjin University Ningbo Branch of china Academy of Ordnance science

The links of Motoman HP6 arc welding robot are considered as an open kinematic chain which consists of a series of rotational joints through concatenation. One end of the open chain is fixed to the base or the earth, and the other end which is free fastens the end executor to complete various duties. Each link of this arc welding robot has four kinds of Denavit-Hartenberg parameters: common normal length between two adjacent links, angle of two adjacent joints, distance between the crossing of common normal length and two joints axes, and angle of two adjacent links. The displacement relation between each link of the Motoman HP6 arc welding robot is introduced, and the kinematic positive-going solution and the kinematic passive-going solution are calculated.

关键词： arc welding robot link Denavit-Hartenberg parameter kinematic positive-going solution kinematicpassive-going solution off-line programming