Chongyi Zhangyuan Tungsten Co.

Ganzhou, China

Chongyi Zhangyuan Tungsten Co.

Ganzhou, China
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Li P.,China University of Geosciences | Li P.,Chinese Academy of Geological Sciences | Liu S.B.,Chinese Academy of Geological Sciences | Shi G.H.,China University of Geosciences | Zhang S.D.,Chongyi Zhangyuan Tungsten Co.
Yanshi Xuebao/Acta Petrologica Sinica | Year: 2015

There are more than one handred metal deposits (chromium, nickle, iron, gold etc. ) distributed in three greenstone belts (Maevatanana, Andriamena and Beforona) from Central Madagascar. In this investigation, we reported major and trace element compositions, LA-MC-ICP-MS zircon U-Pb ages and Lu-Hf isotopic compositions of granites in the greenstone belt from the southwestern Maevatanana, Central-North Madagascar. The granites, mainly composed of biotite and adamellite, belong to aluminous to slight peraluminous K-rich calc-alkaline series and are characterized by high LILE contents (e. g. Rb, Ba, K) , low HFSE contents (e.g. Nb, Ta, Ti) , with ∑ REE = 92.02 × 10-6 and A/CNK = 1.01. The ages of the granite range between 739 ∼ 767Ma. All εHf(t) values are negative, suggesting that their magma sources were from continental basement. Two-stage Hf modle ages of the overgrown and inherited zircons are similar, suggesting that forming age of protolith of the granite was the same as the biotite-amphibole-plagioclase gneiss, and the granite formed by partial melting of the basement. Geochemical features of the granite show similarity to type-I granite, resembling characterstics of the adakite. lt is suggested that the granite was associated with arc magmatism of continental convergence margin between the Tanzanian craton and Dharwar craton, lndia, during Meso-Neoproterozoic (824 ∼ 720Ma) when Rodinia supercontinent broke up with close of the Mozambique Ocean.


Wan L.,Jiangxi University of Science and Technology | Yang S.,Xinda Gold and Silver Development Center | Zhao L.,Chongyi Zhangyuan Tungsten Co. | Li H.,Jiangxi University of Science and Technology
Advanced Materials Research | Year: 2012

In the paper, the four core technologies "low cost and efficient decomposition," "APT property control", "fuzzy exchange and super desorption," "liquid, gas efficient closed-circuit" in Zhangyuan Tungsten Co.,Ltd in the past 20 years are elaborated in all aspects,and the research of wolframite and scheelite closed-circuit smelting process and zero emission technology are also introduced. © (2012) Trans Tech Publications, Switzerland.


Zhao S.,National University of Defense Technology | Zhou X.,National University of Defense Technology | Yu H.,National University of Defense Technology | Wang H.,National University of Defense Technology | And 4 more authors.
Fusion Engineering and Design | Year: 2010

Silicon carbide fiber reinforced silicon carbide composites (SiC f/SiC) are promising candidate materials for fusion applications. The compatibility of SiCf/SiC composites with liquid LiPb is one of the key issues for fusion technologies. Three-dimensional SiCf/SiC composites were fabricated by polymer infiltration and pyrolysis (PIP) process and β-SiC coating was deposited by chemical vapor deposition (CVD) process. The composites were exposed to static liquid LiPb for 500 h at 700°C. The results showed that the liquid LiPb penetrated through the open pores of the cut surface of the composites and reacted with the matrix and fibers, which caused a weight change and a severe degradation of the mechanical property to the uncoated composites. As for the coated composites, the mechanical property was degraded and the weight increased because of the absorption of LiPb, although the CVD SiC coating was compatible with LiPb and protected fibers and matrix beneath. © 2010 Elsevier B.V. All rights reserved.


Yu H.,National University of Defense Technology | Zhou X.,National University of Defense Technology | Wang H.,National University of Defense Technology | Zhao S.,National University of Defense Technology | And 4 more authors.
Fusion Engineering and Design | Year: 2010

Two-dimensional (2D) silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) composite suiting for flow channel insert (FCI) application was successfully fabricated by stacking molding-precursor impregnation and pyrolysis (PIP) process. Plain-woven KD-I SiC fiber fabric was used as the reinforcement. SiC coating was deposited as the fiber/matrix interphase layer by chemical vapor deposition (CVD) technique. Mechanical, thermal and electrical properties of the 2D SiC/SiC composite were investigated. The results show that mechanical properties and through thickness thermal conductivity of the 2D KD-I/PIP SiC composite well meet the FCI application requirements; meanwhile, it seems that the electrical conductivity requirement will also be satisfied with a series of improvements. © 2010 Elsevier B.V. All rights reserved.


Yang H.,National University of Defense Technology | Zhou X.,National University of Defense Technology | Yu J.,National University of Defense Technology | Wang H.,National University of Defense Technology | Huang Z.,Chongyi Zhangyuan Tungsten Co.
Ceramics International | Year: 2015

In order to investigate the effect of microwave sintering time on the mechanical properties of SiC/SiC composites, four groups of SiC/SiC composites were fabricated via polymer impregnation and pyrolysis (PIP) process using microwave heating with different sintering time- 0.5. h, 1.0. h, 1.5. h and 2.0. h (at 1100. °C) at each PIP cycle. The flexural properties, the interfacial debonding strength between SiC fiber and matrix of the fabricated SiC/SiC composites and the SiC fiber filament strength after heat treatment were investigated. The results indicated that after heat treatment the residual strength of SiC fibers as reinforcement decreased and the interfacial debonding strength increased with the increase of the microwave sintering time at each PIP cycle, which together resulted in the changing tendency that the flexural strength and toughness of the as-fabricated SiC/SiC composites increased firstly and then decreased. © 2015 Elsevier Ltd and Techna Group S.r.l.


Yang H.,National University of Defense Technology | Zhou X.,National University of Defense Technology | Yu J.,National University of Defense Technology | Wang H.,National University of Defense Technology | Huang Z.,Chongyi Zhangyuan Tungsten Co.
Ceramics International | Year: 2015

SiC/SiC composites were fabricated by the PIP process via microwave and conventional heating from 800. °C to 1200. °C. The flexural properties and microstructures of the as-fabricated SiC/SiC composites were investigated. The results indicated that the flexural strength and toughness have the same changing tendency for both conventional and microwave sintering. However, at the same PIP sintering temperature, the flexural properties of the microwave sintered SiC/SiC are higher than that of the conventional sintered ones. The higher residual strength of SiC fibers properties and more cracks in the composite matrix resulting from higher heating rates of the microwave sintering brought about the better flexural properties. © 2015 Elsevier Ltd and Techna Group S.r.l.


Yu H.J.,National University of Defense Technology | Yu H.J.,University of Bristol | Zhou X.G.,National University of Defense Technology | Zhang W.,National University of Defense Technology | And 3 more authors.
Composites Science and Technology | Year: 2011

Three-dimensional (3D) silicon carbide (SiC) matrix composites reinforced with KD-I SiC fibres were fabricated by precursor impregnation and pyrolysis (PIP) process. The fibre-matrix interfaces were tailored by pre-coating the as-received KD-I SiC fibres with PyC layers of different thicknesses or a layer of SiC. Interfacial characteristics and their effects on the composite mechanical properties were evaluated. The results indicate that the composite reinforced with as-received fibre possessed an interfacial shear strength of 72.1 MPa while the composite reinforced with SiC layer coated fibres had a much higher interfacial shear strength of 135.2 MPa. However, both composites showed inferior flexural strength and fracture toughness. With optimised PyC coating thickness, the interface coating led to much improved mechanical properties, i.e. a flexural strength of 420.6 MPa was achieved when the interlayer thickness is 0.1μm, and a fracture toughness of 23.1 MPam1/2 was obtained for the interlayer thickness of 0.53μm. In addition, the composites prepared by the PIP process exhibited superior mechanical properties over the composites prepared by the chemical vapour infiltration and vapour silicon infiltration (CVI-VSI) process. © 2011 Elsevier Ltd.


Li M.,National University of Defense Technology | Zhou X.,National University of Defense Technology | Yang H.,National University of Defense Technology | Yu J.,National University of Defense Technology | And 2 more authors.
Journal of Alloys and Compounds | Year: 2016

SiC/SiC composites coated with the pyrolytic carbon (PyC) interphase coatings of different thickness were fabricated by polymer infiltration and pyrolysis (PIP) process using microwave sintering at 1100 °C assisted with the hot mould pressing pressure of 3 MPa. The effects of the PyC coating thickness on the densification, the flexural properties and microstructures of the fabricated SiC/SiC composites were investigated via the mercury intrusion test, the computed tomography (CT) technique and scanning electron microscopy (SEM). The results indicate that the preforms coated with thinner PyC coatings, which have better flexibility under the hot mould pressing process, bring SiC/SiC composites with higher densification degrees, due to their better flexibility under the hot press moulding process. Simultaneously, thicker PyC coatings result in weaker interphase debonding between SiC fibers and matrix quantified by the single fiber push-out test. Too thick or too thin PyC coatings both make against the flexural properties, as they will cause the debonding between SiC fibers and matrix too early or too late. The PyC coating thickness-0.20 μm is approximate for the better flexural properties. © 2016 Elsevier B.V.


Yang H.,National University of Defense Technology | Zhou X.,National University of Defense Technology | Yu J.,National University of Defense Technology | Wang H.,National University of Defense Technology | Huang Z.,Chongyi Zhangyuan Tungsten Co.
Journal of Alloys and Compounds | Year: 2016

SiC/SiC composites were fabricated by polymer impregnation and pyrolysis (PIP) process via microwave and conventional heating at 800 °C, 900 °C, 1000 °C and 1100 °C. The effects of sintering heating types and sintering temperatures on the densification process and pore distributions of the fabricated SiC/SiC composites were studied. The densification processes were discussed in the form of the weight gain rates at each PIP cycle. The pore location distributions were observed by scanning electron microscopy (SEM) and computed tomography (CT) technique. The porosity and pore size distributions were quantified by the mercury intrusion test. The results indicate that lower heating rates and higher sintering temperatures are benefit to the densification of the SiC/SiC composites. But the more micro-cracks generated from higher heating rates of microwave sintering (∼40 °C/min) make the flexural strength and toughness of the SiC/SiC composites higher than that of the conventional sintered ones. © 2015 Elsevier B.V. All rights reserved.

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