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Lu L.,General Research Institute for Nonferrous Metals, China | Lu L.,University of Science and Technology Beijing | Zhang S.,General Research Institute for Nonferrous Metals, China | Xu J.,General Research Institute for Nonferrous Metals, China | And 2 more authors.
International Journal of Heat and Mass Transfer | Year: 2017

High frequency induction heating process of titanium wire is investigated numerically and experimentally. The electromagnetic thermal and fluid fields during high frequency induction heating process are calculated. The effects of current frequency and current value of coil on the thermal and flow fields are numerically studied. The change of the applied current has profounder influence on the melting rate than the change of current frequency did. The simulation results are verified by experiments, and good agreement with simulation. With the ability to observe temperature distribution in titanium wire during high frequency induction heating, the numerical simulation method is demonstrated to be a cost-effective tool in predicting the process of high frequency induction heating of titanium wire. © 2017 Elsevier Ltd


Xu X.-F.,East China Jiaotong University | Xu X.-F.,Central South University | Hong L.-L.,East China Jiaotong University | Xiao P.,Central South University | And 2 more authors.
Fenmo Yejin Cailiao Kexue yu Gongcheng/Materials Science and Engineering of Powder Metallurgy | Year: 2013

Using nickel particles as catalysts, C3H6, H2, N2 as carbon source, carrier gas and diluent gas, respectively, the carbon nano-tube/carbon nano-fiber (CNT/CNF) were self-grown on the surface of carbon fibers (CFs) by the method of catalytic chemical vapor deposition (CCVD) to make surface modification of CF. The structures of CNT/CNF were observed by SEM and TEM. Surface structure of untreated and treated carbon fiber (CF) were observed by Raman spectra. The results show that the surface modification can decrease the amount of disordered carbon and amorphous carbon, improve the surface graphitization of carbon fiber. A new "Fracture-Adsorption-Diffusion-Deposition" mechanism model for CCVD growth of CNT/CNF is suggested based on these analyses.


Lu L.L.,General Research Institute for Nonferrous Metals, China | Lu L.L.,University of Science and Technology Beijing | Zhang S.M.,General Research Institute for Nonferrous Metals, China | Xu J.,General Research Institute for Nonferrous Metals, China | And 5 more authors.
Materials Science Forum | Year: 2016

The solidification characterization of K418 alloy powders prepared by argon atomization was studied, and thermal parameters of the alloy powder during solidification process were calculated. The results show that powder morphology is spherical shape, the average diameter of the powder is 55μm, the amount of less 100μm powder is about 90 percent, the solidification microstructure of powders particle surface are dentrite and cellular structure. Decreasing the particle size, the microstructures of particle interior change from dentrite in major to cellular structures, and the structure is more uniformed. The length of secondary dentritic arm and the cooling rate as a function of K418 alloy powders size is established, the cooling rate increases with a decrease of the powder particle size, the cooling rate is in the range of 104K.S-1-106K.S-1. © 2016 Trans Tech Publications, Switzerland.


Yin J.,Central South University | Zhang H.-B.,Central South University | Xiong X.,Central South University | Tan C.,Central South University | Lu C.-T.,Beijing COMPO Advanced Technology Co.
Fenmo Yejin Cailiao Kexue yu Gongcheng/Materials Science and Engineering of Powder Metallurgy | Year: 2014

Carbon fiber reinforced carbon and copper (C/C-Cu) composites were prepared by a combination of chemical vapor infiltration (CVI) and melt copper impregnation by pressure. 3 kinds of C/C-Cu composites with different densities of porous carbon/carbon composites (C/C substrates) were prepared and their compressive properties were tested on CSS-44100 electronic tensile testing machine. The effect of C/C substrate density on compressive property of C/C-Cu composites was studied. The results show that C/C-Cu composites have high compressive strengths, which have small differences between parallel and vertical direction. With the increase of the C/C substrate density, the compressive strength of C/C-Cu composites increases and the anisotropy improves. The one with highest density has the highest compressive strength of 323.8 and 326.6 MPa. The composites are shearing along with 45° diagonal line in vertical direction, while destroyed by delaminating split in parallel direction. ©, 2014, Central South University. All right reserved.


Zhao X.-M.,General Research Institute for Nonferrous Metals, China | Xu J.,General Research Institute for Nonferrous Metals, China | Zhu X.-X.,General Research Institute for Nonferrous Metals, China | Zhu X.-X.,Beijing COMPO Advanced Technology Co. | And 2 more authors.
International Journal of Minerals, Metallurgy and Materials | Year: 2012

17-4PH stainless steel powders were prepared using a supersonic nozzle in a close-coupled gas atomization system. The characteristics of powder particles were carried out by means of a laser particle size analyzer, scanning electron microscopy (SEM), and the X-ray diffraction (XRD) technique. The results show that the mass median particle diameter is about 19.15 μm. Three main types of surface microstructures are observed in the powders: well-developed dendrite, cellular, and cellular dendrite structure. The XRD measurements show that, as the particle size decreases, the amount of fcc phase gradually decreases and that of bcc phase increases. The cooling rate is inversely related to the particle size, i.e., it decreases with an increase in particle size. © University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg 2012.


Zhao X.M.,General Research Institute for Nonferrous Metals, China | Xu J.,General Research Institute for Nonferrous Metals, China | Zhu X.X.,General Research Institute for Nonferrous Metals, China | Zhu X.X.,Beijing COMPO Advanced Technology Co. | Zhang S.M.,General Research Institute for Nonferrous Metals, China
Materials Science Forum | Year: 2011

The aspiration pressure variation at the tip of metal delivery tube in the supersonic atomization nozzle during gas-only atomization performance had been investigated in this work. The results reveal that the aspiration pressure is subambient at all operating pressures. A general trend is that with increasing atomization gas pressure, the value of aspiration pressure decreases at P 0 between 0.5 and 1.5MPa, then increases as P0 ranges from 1.5∼3.5MPa, finally decreases again at higher gas pressure (P 0>∼3.5MPa). When P0>2.0MPa, as the included angle α augments, the aspiration pressure ΔP increases. Meanwhile, the change range of aspiration pressure ΔP significantly enlarges when the jet included angle α raises from 16 to 28°. The lager is the apex angle β of metal delivery tube, the greater is the aspiration pressure ΔP. And as the protrusion length of melt delivery tube h increases, the aspiration pressure ΔP decreases gradually. © (2011) Trans Tech Publications.


Qu J.,General Research Institute for Nonferrous Metals, China | Qu J.,Beijing COMPO Advanced Technology Co. | Xu J.,General Research Institute for Nonferrous Metals, China | Xu J.,Beijing COMPO Advanced Technology Co. | And 4 more authors.
Advanced Materials Research | Year: 2013

This research investigates the microstructure and growth behavior of the intermetallic compound(IMC) of Sn-1.0Ag-0.5Cu,Sn-1.0Ag-0.5Cu-0.05Ni and Sn-1.0Ag-0.5Cu-0.05N-0.02B/Cu solder joint interface. The interfacial reactions between Cu and the solders at 250±1°C were examined. Experimental results indicated that the IMCs of the above alloy systems on the soldering interface were Cu6Sn5 and (Cux, Ni1-x)6Sn5, respectively. The grain size of primary Sn decreased observably with the micro addition of B and a large number of fine reinforcement particles were found in the solder. With the aging time increasing, the (Cux, Ni1-x)6Sn5 micrograph of the Sn-1.0Ag-0.5Cu-0.05N-0.02B solder joint interface was changed from sawtooth-like to shape-layer, but the thickness of IMCs increased unobservably. © (2013) Trans Tech Publications, Switzerland.


Jin S.,Beijing Compo Advanced Technology Co. | Hu Q.,Beijing Compo Advanced Technology Co. | An N.,General Research Institute for Nonferrous Metals, China | Zhu X.,General Research Institute for Nonferrous Metals, China | And 3 more authors.
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2014

The effect of Cr on the oxidation resistance of lead free solder Sn-3.0Ag-0.5Cu (SAC305) at 280℃ was studied. Based on the analysis of the surface oxidation with scanning electron microscope (SEM) and auger electron spectroscopy (AES), the mechanism of oxidation resistance improvement was also discussed. The effects of Cr on the microstructure and surface wettability of lead-free solder were revealed. The results showed that the oxidation resistance of lead-free solder could be effectively improved by Cr addition. Cr element in the molten solder surface was easy to generate Cr2O3, resulting in that Sn oxiding preceded to form a dense protective oxide film, thus protecting the further oxidation of the solder. When Cr content was 0.1%(mass fraction), the liquid solder formed a smooth and compact oxide layer on the surface. The oxidation resistance of liquid SAC305-0.1Cr was correspondingly improved. In addition, the surface wettability reduced after the Cr addition, and as the Cr content increased, the solder spreading area gradually reduced. It was also shown that the addition of P could improve the surface wettability of SAC305-0.1Cr.


Qu J.F.,Beijing COMPO Advanced Technology Co. | Qu J.F.,General Research Institute for Nonferrous Metals, China | Xu J.,Beijing COMPO Advanced Technology Co. | Xu J.,General Research Institute for Nonferrous Metals, China | And 4 more authors.
Applied Mechanics and Materials | Year: 2013

The solder/substrate reactions, for Sn-1.0Ag-0.5Cu, Sn-1.0Ag-0.5Cu-0.05Ni and Sn-1.0Ag-0.5Cu-0.05Ni-0.02B, were evaluated in what concerns the melting temperature, microhardness, morphology of the solder and chemical composition of the interface layer. The phases formed at the interface between the Cu Substrate and a molten lead-free solder were studied with different stage times. The evaluation of their chemical compositions were performed by Scanning Electron Microscopy(SEM) and Energy Dispersive Spectrometer(EDS). © (2013) Trans Tech Publications, Switzerland.


Zhang F.,Beijing Compo Advanced Technology Co. | Zhang Q.,Beijing Compo Advanced Technology Co. | Hu Q.,Beijing Compo Advanced Technology Co. | Zhu X.,Beijing Compo Advanced Technology Co.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2014

The effects of Mn, Zn elements on the low-silver Sn-Ag-Cu lead-free solder joint interface microstructure and its mechanical properties were studied. The results show that Mn, Zn can inhibit the growth of intermetallic compound (IMC) layer of the as-soldered joints, such as Cu6Sn5 and Cu3Sn. With adding Zn, Mn to the solder, the directional growth of the solder matrix in the solder joint is changed. By comparing the aged solder joint, it is found that Mn, Zn addition can restrain the coarsening of Cu6Sn5 and Cu3Sn intermetallic layer during the aging process. This is the reason why adding Mn, Zn can increase the solder joint's stability and reliability. Mechanical property tests show that Mn, Zn can increase the tensile strength and shear strength of the solder joint. However, adding Mn, Zn too much will worsen the mechanical property because of the wettability problem. When about 0.2wt%Zn and 0.05wt%Mn was added, both the tensile and shear strength came to the best value generally at the same time. The morphology of solder joint fracture shows that it is ductile fracture under the tensile and shear loads, and that is why the Mn, Zn IMC dispersed phase can improve the mechanical properties of the joint.

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