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Liang S.,Xi'an University of Science and Technology | Liang S.,Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology | Chen L.,Xi'an University of Science and Technology | Yuan Z.,Xi'an University of Science and Technology | And 6 more authors.
Materials Characterization | Year: 2015

In this article, novel W-Cu composites reinforced with topologically-inserted tungsten fibers (Wf) have been fabricated by hot-press sintering and infiltration method. By pre-sputtering of ∼ 100 nm thick chromium layer onto the surface of Wf, the contiguity or connectivity between Wf and neighboring tungsten particles (Wp) or Cu after sintering and infiltration was enhanced. Combined SEM, TEM and STEM techniques confirmed that the intact interfaces of Wf/Wp and Wf/Cu free from precipitates, impurities and porosities would provide desirable strength and ductility. Further mechanical tests also validated its superior compressive strength and plasticity at various temperatures, together with significantly improved tensile strength (by 23.6%) and hardness (by 9.3%) for the W-Cu composite after reinforcement with Cr-coated Wf, which promotes the engineering application of the composite greatly. © 2015 Elsevier Inc. All rights reserved.


Zheng L.-Y.,Xi'an University of Science and Technology | Xiao P.,Xi'an University of Science and Technology | Xiao P.,Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2015

Cu-7.5Ni-5Sn-xV alloys were prepared in a high frequency induction melting furnace. The cast alloy specimens were homogenised, solution and aging treated. Microstructure and properties of the alloys were studied by means of SEM, TEM, hardness test and conductivity measurement. The results show that the microstructure of the alloy is refined and the discontinuous precipitation at grain boundaries during aging is inhibited. The electrical conductivity of the Cu-7.5Ni-5Sn-xV alloys increases with increasing aging time, while the hardness of the alloys increases and then decreases. The peak hardness of Cu-7.5Ni-5Sn is 274.6 HV after ageing treatment, and the hardness of Cu-7.5Ni-5Sn-0.2V and Cu-7.5Ni-5Sn-0.5V alloys reaches 276 HV and 289 HV after ageing at 380℃ for 7 h, respectively, due to the formation of coherent Ni3V phases with the matrix. Addition of V in Cu-7.5Ni-5Sn alloy extends the alloy hardening peak aging time and enhances the hardening effect. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.


Song Y.,Xi'an University of Science and Technology | Song Y.,Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology | Liang S.,Xi'an University of Science and Technology | Liang S.,Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology | And 2 more authors.
Ceramics International | Year: 2014

Single phase of green-emitting X2-(Y,Gd)SiO5:Tb3+ phosphoqr was successfully prepared at 1250 °C by a co-precipitation process. The photoluminescence of as-prepared Y1.9SiO5:0.1Tb3+ and Y1.85Gd0.05SiO5:0.1Tb3+ were investigated in vacuum ultraviolet region. Under 147 nm excitation, the phosphors showed main emission peak at 543 nm attributed to the 5D4→7F5 transition of Tb3+. According to the relative emission intensity of samples with different composition, the optimal substitution proportions of Tb and Gd for Y were determined to be 10% and 5%, respectively. Besides, Y1.85Gd0.05SiO5:0.1Tb3+ maintained the short decay time of Y2SiO5:Tb3+ phosphor only 3.5 ms, which is much shorter than the commercial green-emitting phosphor Zn2SiO4:Mn2+. As showed in the excitation spectrum, the 141 and 175 nm excitation bands were assigned to the charge transfer bands of Y-O and Gd-O, respectively. Compared to Y2SiO5:Tb3+, Gd3+ provided another energy transfer channel from matrix to the luminescence center Tb3+, thereby enhancing the photoluminescence efficiency. The projected density of states of Y2SiO5 and Gd2SiO5 were also discussed in this work trying to understand the charge transfer mechanics of this phosphor. © 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.


Wang F.,Xi'an University of Science and Technology | Yang Q.,Xi'an University of Science and Technology | Yang Q.,Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology | Zou J.,Xi'an University of Science and Technology | And 3 more authors.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2015

The 92%Ni-4%B-4%Si alloy powers were prepared by mechanical alloying of nickel carbonyl, boron and silicon powders. The morphology, average particle size, phase composition and initial melting temperature were investigated by laser particle size analyzer, SEM, XRD and DSC. The results show that when the ball milling time is 30 h, the morphology of the 92%Ni-4%B-4%Si alloy powders becomes spherical, the alloying elements B and Si completely dissolve into the Ni matrix, and the initial melting temperature decreases to 1038℃. When the ball milling time is up to 80 h, the lattice structure collapses and the amorphous transformation tends to occur. The infiltration of 92%Ni-4%B-4%Si alloy powders after 40 h ball milling and the loosely packing nickel powders at 1100℃ lead to the high density sintered alloy through metallurgical bonding. ©, 2015, Rare Metals Materials and Engineering Press. All right reserved.


Song Y.,Xi'an University of Science and Technology | Song Y.,Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology | Liang S.,Xi'an University of Science and Technology | Liang S.,Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology | And 5 more authors.
Materials Letters | Year: 2015

In this work, we reported the fabrication and characterization of CaWO4@CaWO4:Dy3+ core/shell microspheres via a facile hydrothermal method without organic surfactant. The samples were characterized by XRD, SEM, EDS and photoluminescence. These core/shell microspheres were constructed by nanoparticles through a self-assembly way without any organic surfactant or template. The solid and hollow microspheres prepared through positive and reverse precipitation respectively were used as the precursor. The reduction of the surface energy and high temperature in the hydrothermal process provided the kinetics and thermodynamics motion of the self-assembly course respectively. The direct doped CaWO4:Dy3+ and CaWO4@CaWO4:Dy3+ (core-shell) microspheres show characteristic emission of Dy3+. The luminescent intensity of the core/shell phosphor was enhanced with respect to the direct doped one of the same doping concentration. The possible mechanism was also proposed.


Yang Q.,Xi'an University of Science and Technology | Yang Q.,Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology | Liang S.,Xi'an University of Science and Technology | Liang S.,Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology | And 2 more authors.
Science China Technological Sciences | Year: 2013

In order to improve the corrosion resistance of nanoporous coppers (NPCs), the electroless Ni-P coated NPCs were prepared in plating solutions with different pH values (5, 8, 11) and complexing agent (actic acid, citric acid). The morphologies and corrosion resistances of the as-prepared samples were investigated. The results showed that the double complexing agent composed of lactic acid and citric acid is relatively suitable for preparing the Ni-P coated NPC with three-dimensional continuous interpenetrating ligament-channel structures, and the uniform ligaments and nanoporous channels could be obtained at pH8. The Ni-P coated NPC showed higher corrosion potentials than NPC in H2SO4, NaOH and NaCl corrosion solutions. © 2013 Science China Press and Springer-Verlag Berlin Heidelberg.

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