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Luo Q.,Yunnan University | Gan G.-Y.,Kunming University of Science and Technology | Gan G.-Y.,Key Laboratory of Advanced Materials of Precious Nonferrous Metals | Gan G.-Y.,Key Laboratory of Advanced Materials of Yunnan Province
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2012

The silver powder as a conductive phase in the silver paste mainly plays the role of conducting electricity. The composition, morphology, particle sizes and concentration of the conductive phase have relatively large influences on the electrical properties of the silver paste. The influences of the morphology, concentration and gradation of the different silver powders on the properties of the silver paste were studied and the conductivity mechanism of the silver film was also discussed. The results showed that the conductive properties of silver films were effectively increased by the addition of flake silver powder. When the content of the flake silver powder reached 80% (in mass) of the total sliver powders, square resistance reduced from 15.65 mΩ/□ with only spherical silver powder to 7.41 mΩ/□. When the mass percentage of the mixed silver powders as a conductive phase was 73% in the sliver paste, the conductive properties of the silver film was the best. Source


Yan F.C.,Kunming University of Science and Technology | Teng Y.,Kunming University of Science and Technology | Yan J.K.,Kunming University of Science and Technology | Du J.H.,Kunming University of Science and Technology | And 3 more authors.
Materials Science Forum | Year: 2016

In order to study the effects of composition ratio of silver paste and the sintering process on the properties of the silver film after sintering, the effects of different ratios of silver powders, glass powders and organic carrier in silver paste and different sintering temperatures and sintering time on the adhesion force and square resistance of the silver film were studied. The morphology of the sintered silver film was observed by SEM. The results showed that the silver film sintered at 760°C for 6 seconds had better properties after sintering when the ratio of silver powders, glass powders and organic carrier in silver paste was 80:5:15 and the silver powders was composed of spherical silver powders and flake silver powders at the ratio of 94:6. The adhesion force and square resistance of the silver film were 8.25 N and 3.47mΩ /□, respectively. © 2016 Trans Tech Publications, Switzerland. Source


Xiao B.,Key Laboratory of Advanced Materials of Precious Nonferrous Metals | Xiao B.,Xian Jiaotong University | Feng J.,Key Laboratory of Advanced Materials of Precious Nonferrous Metals | Zhou C.T.,Xian Jiaotong University | And 4 more authors.
Physica B: Condensed Matter | Year: 2010

The first principles calculations are performed to investigate the elastic constants and thermodynamic parameters of X2B compounds. The calculated elastic constants for these borides indicate that they are mechanically stable structures. The bulk modulus of them range from 230 to 310 GPa and the largest bulk modulus value is attributed to W2B. Furthermore, the scale relation between C44 and bulk modulus is observed in our case. Heat capacity is calculated based on Debye's quasi-harmonic approximation, and we decomposed the heat capacity into two contributions to find that electron excitations dominated the heat capacity at low temperatures. The hardness of X-B and B-B bonds is calculated using a semi empirical hardness theory. © 2009 Elsevier B.V. Source


Zhang L.,Kunming University of Science and Technology | Zhang L.,Key Laboratory of Advance Materials of Yunnan Province | Zhang L.,Key Laboratory of Advanced Materials of Precious Nonferrous Metals | Du J.,Kunming University of Science and Technology | And 11 more authors.
Advanced Materials Research | Year: 2012

Porous alumina insulation materials were prepared by the combination method of gelcasting and foaming. The effects of the amount of blowing agent, the solid volume, and the sintering temperature on porosity of aluminum oxide ceramic were studied. The result showed that, when the amount of blowing agent is 1wt %, the solid volume is 45 vol % and the sintering temperature is 1500°C, the porous alumina ceramics with high porosity, small pore diameters, evenly distributed, high bending strength and low heat conductance can prepared. Source


Feng J.,Key Laboratory of Advanced Materials of Precious Nonferrous Metals | Feng J.,Kunming University of Science and Technology | Xiao B.,Key Laboratory of Advanced Materials of Precious Nonferrous Metals | Xiao B.,Kunming University of Science and Technology | And 6 more authors.
Procedia Engineering | Year: 2012

White cast iron has been widely used as a wear resistance material for a long time in many industrial applications. It is well-known that the elastic properties of the alloy can be greatly affected by reinforced particles or precipitated phases. For white cast iron, the precipitated carbides usually refer to Fe 2C, Fe 3C, Fe 23C 7, etc. In practice, small amount of Cr and B is added into ordinary white cast iron in order to stabilize Fe xC-type carbides, as a result, the obtained carbides can be represented as (Fe, Cr) x C(B). When compared with the ordinary white cast iron, the elastic performance of Cr cast iron is enhanced. In recent years, first principles calculations based on density functional theory (DFT) have become a powerful tool to investigate the electronic, stability and mechanical properties of condensed matter. It is very suitable to study the equilibrium properties of compounds that cannot be synthesized on a large scale or are very difficult to obtain enough samples for mechanical tests. We have also used first principles calculations to compare the ground state properties of these compounds, but our main emphasis is on the mechanical aspect. The calculated mechanical properties of Cr 7C 3, Fe 2B and Fe 3C may be extremely useful for us to clearly understand the origin of such mechanical performance, because the mechanical response of solids, as we knew, is determined by chemical bonding among distinct atoms. © 2011 Published by Elsevier Ltd. Source

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