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Wang P.,Shanghai Hiwave Advanced Materials Technology CO. | Liu W.,Shanghai Hiwave Advanced Materials Technology CO. | Chen L.,Shanghai Hiwave Advanced Materials Technology CO. | Mu C.,Wenzhou Hongfeng Electrical Alloy Co. | And 2 more authors.
RSC Advances | Year: 2015

As one of the most industrially important metals, copper (Cu) was successfully reinforced with graphite nanosheets (GNSs). A nacre-inspired laminated GNSs/Cu composite material was fabricated by a combination of ball-milling and hot-rolling techniques. During the ball-milling process, the GNSs were in situ produced from graphite exfoliation. The Cu-GNSs composite ingot was hot-rolled into a belt to form a laminated structure. The laminated Cu-GNSs composite material showed improved mechanical properties observed from tensile and three-point bending tests. The Young's modulus of Cu-GNSs composites was up to 170 GPa and the bending strength reached 660 MPa. This processing route was also advantageous in low-cost, mass-producing manufacture. © The Royal Society of Chemistry 2015. Source

Wei Z.,Zhejiang University | Zhang L.,Zhejiang University | Zhang L.,Zhejiang California International NanoSystems Institute | Shen T.,Zhejiang California International NanoSystems Institute | And 6 more authors.
Journal of Materials Engineering and Performance | Year: 2016

Silver-zinc oxide (Ag/ZnO) electrical contact material is widely used as contacts of the medium duty switching devices. Effects of modified ZnO on properties of Ag/ZnO electrical contact material were investigated in this work. NiO and CuO were introduced to modify spherical ZnO by a chemical solution nano-coating method. Ag/ZnO contacts prepared using the modified spherical ZnO were produced by powder metallurgy (PM) method in a muffle furnace in temperature ranges from 750 to 900 °C. Results show that electrical conductivity, stability of relative density, and Vickers’ hardness of Ag/ZnO electrical contact material can be improved by the addition of NiO because of the formation of NiO solid solution Zn0.2Ni0.8O. The addition of CuO to Ag/ZnO electrical contact material makes arcing energy and mass loss lower. Since this is attractive for a longer service life, using NiO and CuO co-modified ZnO as a second phase may be a promising way to improve properties of Ag/ZnO electrical contact material. Hence, the presented results could also be useful for the design of a new Ag/ZnO electrical contact material. © 2016 ASM International Source

Qiao X.,Zhejiang University | Shen Q.,Zhejiang University | Shen Q.,Zhejiang California International NanoSystems Institute | Zhang L.,Zhejiang University | And 6 more authors.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2014

A novel method was presented to prepare Ag/SnO2 (12 wt% SnO2) electrical contact materials. First, Ag-SnO2 nano composite powder with 42 wt% SnO2 synthesized by a coprecipitation method was characterized. XRD results reveal that the synthesized composite powder is composed of cubic Ag and rutile type of SnO2. SEM and TEM images show that nano-Ag and nano-SnO2 particles are homogeneously dispersed in the composite powder. The preparation process of nano composite powder was analyzed with the help of the TG-DTA curves of the precipitation. Then, the obtained Ag-SnO2 nano composite powder was mixed with Ag powder to prepare Ag/SnO2 electrical contact materials (ECM) by powder metallurgy process and the prepared Ag/SnO2 electrical contact materials was characterized. The results demonstrate that owing to the higher dispersion of nano SnO2 particles in Ag matrix, the physical properties of ECM prepared by the new method, such as the density, hardness and conductivity are better than that by the traditional method. Copyright © 2014, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved. Source

Jiang W.,Shanghai JiaoTong University | Zhao C.-L.,Beijing University of Posts and Telecommunications | Li S.-H.,Shanghai JiaoTong University | Chen L.,Wenzhou Hongfeng Electrical Alloy Co.
Neurocomputing | Year: 2014

Detecting spatiotemporal pattern from noisy sequences of events plays a very important role in presence sharing, Internet of Things (IoT) and many other fields. As pointed out in existing literature, the core activities of these applications involve event notifications. However, excessive number of event notifications will lead to user's intolerability. Existing literature proposed a Spatiotemporal Pattern Learning Automata (STPLA) to solve this problem effectively in both stationary and non-stationary environments. However, one limitation of the STPLA is that it cannot be both memory balanced and bias toward any of the two actions, i.e., "suppress" or "notify". To solve this problem, this paper proposed a new Learning Automata based approach, named as Spatiotemporal Tunable Fixed Structured Learning Automata (STP-TFSLA), for online tracking of event pattern. Furthermore, we also show that the STP-TFSLA is with small memory footprint and is able to cope with non-stationary environment. © 2014 Published by Elsevier B.V. Source

Qiao X.-Q.,Zhejiang University | Zhang L.-J.,Zhejiang University | Chen L.-S.,Wenzhou Hongfeng Electrical Alloy Co. | Chen L.-S.,Zhejiang California International Nano Systems Institute | And 6 more authors.
Gongneng Cailiao/Journal of Functional Materials | Year: 2013

Hollow SnO2 microspheres with an open structure were successfully synthesized by hydrothermal method, using sodium stannate and urea as starting materials. Effects of concentration of urea and hydrothermal time on the formation of hollow SnO2 microspheres were studied. The as-prepared samples were characterized by XRD, SEM and TEM and the formation mechanism of hollow spheres was discussed. Results indicated that hollow SnO2 microspheres with a diameter of about 2 μm had a shell thickness of 250 nm and were built from nanosheets or nanocrystals. Urea not only played an important role in the SnO2 self-assembly into microsphere, but also acted as the soft template resource for the formation of hollow structure. Meanwhile, this special open structure formed by the escaping of bubbles provides fast channel for the introducing of functional particles and had a very good application prospects. Source

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