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Development of Novel Binder for Hardmetal powder Extrusion Molding

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Journal of Materials Science & Technology 2002年第6期18卷 569-571页

作者： Jicheng ZHOU and Baiyun HUANGstate key laboratory for powder metallurgy, central south university , changsha 410083, china Lab. for Power Metall. Central South Univ. Changsha 410083 China

A novel binder system for hardmetal powder extrusion moulding (PEM) process has been developed. The binder system comprises a major fraction of a mixture of low molecular weight components (LMWCs) and a minor fraction of very finely dispersed polymer. The feedstocks are mixed as a thick slurry at a suitable temperature and are rapidly homogenized by stirring at an adequate shear force. The binders are removed by thermal debinding. The thermal debinding mechanism has been investigated by thermogravimetry (TG) and differential thermogravimetry (DTG). At the first stage of debinding, the LMWCs are removed. These open up pore channels which allows much faster removal of the remaining polymer component during the subsequent stage. The microstructures of the moulded green parts were observed by scanning electron microscopy (SEM). The debound samples were sintered at different temperatures, and the sintered samples properties were measured.

关键词： Binder Thermal debinding Hardmetal powder extrusion moulding

Direct Electrodeposition of Cu-Ni-W Alloys for the Liners for Shaped Charges

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Journal of Materials Science & Technology 2010年第5期26卷 429-432页

作者： Hanwei He and Shouya Jia state key Lab of powder metallurgy,central south university,changsha 410083,china [a] state key Lab of powder metallurgy central south university changsha 410083 china

The Cu-Ni-W alloys for the liners for shaped charges were successfully prepared by direct current（DC） *** influence of cathode current density on morphology,microstructure and composition of the Cu-Ni-W alloys was investigated by means of scanning electron microscopy（SEM）,X-ray diffraction（XRD） and energy dispersive spectrometry（EDS）.With the increasing of current density,the copper content reduces gradually and the nickel and tungsten content increase; the crystallite size is *** the current density is 15 A/dm 2 the tungsten content reaches 12.96 wt pct,and the crystallite size is submicron *** Cu-Ni-W alloy is face-centered cubic（fcc） solid *** of the Cu-Ni-W alloys take on（220） texture.

关键词： Electrodeposition Cu-Ni-W alloy Cathode current density

Thermodynamic analysis on synthesis process of diamond

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Journal of central south university 2001年第3期13卷 156-160页

作者： YI Jian-hong, PENG Yuan-dong (state key laboratory for powder metallurgy, central south university, changsha 410083, china) 1. state key laboratory for powder metallurgy Central South University 410083 Changsha China

Based upon the thermodynamic analysis of the nucleation of d iamond crystal, the effects of synthesis temperature and pressure on the nucleat ion of diamond crystal, diamond growth and output of diamond crystal, particle s ize and strength were discussed. The results show that the excess pressure has a n important effect on the critical radius of nucleation and thermodynamic b a rrier in the formation of a critical nucleus. Considering the excess pressure, t he expression of diamond nucleation rate was obtained.

关键词： diamond synthesis pressure temperature nucleation growth

A Novel Method for Preparation of TaC Coating on C/C Composite Material

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Journal of Materials Science & Technology 2005年第3期21卷 381-385页

作者： Hanwei HE, Kechao ZHOU and Xiang XIONG state key Lab of powder metallurgy, central south university, changsha 410083, china Lab. of powder metallurgy Central South University Changsha 410083 China

A new method for preparation of TaC coating on C/C composite material is reported. The amorphous ethylate tantalum jellied as the precursor is prepared and spread densely on the surface of the C/C composite material so as to form a multilayer film. In a graphitization furnace the multilayer film is transformed into TaC coating at various temperatures. Ethylate tantalum film is characterized by FT-IR (Fourier transform infrared) spectra, XRD (X-ray diffraction) and SEM (scanning electron microscopy) and TaC coating is characterized by XRD and SEM. At 1200℃ the coating contained TaC and Ta2O5, and at above 1400℃ only TaC is formed. The coating formed at 1600℃ is a continuous stratum structure, and that formed at 1600℃ is a porous net structure. Analysis on thermodynamics and formation mechanism of TaC indicates that, after ethylate tantalum is decomposed, Ta2O5 is first produced and then transformed into Ta2C, and newly formed Ta2C is transformed into TaC by the sufficient C at last.

关键词： C/C composite TaC coating Ethylate tantalum

Growth of Hydroxyapatite Crystal in the Presence of Origanic Film

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Journal of Materials Science & Technology 2004年第2期20卷 223-226页

作者： Yong LIU, Suping HUANG, Xiaohong DAN and Kechao ZHOUstate key laboratory for powder metallurgy, central south university, changsha 410083, china Lab. for powder Metall. Central South Univ. Changsha 410083 China

The growth of hydroxyapatite (HAp) crystal in the presence of hexadecylamine was investigated. Due to its high polarity and high charge density, the organic film could increase the ion supersaturation on its surface. Therefore the growth of pure HAp crystals was accelerated. Moreover, the positive headgroups of the organic film could act as recognized nucleation sites and orient the growth of HAp crystals along the direction.

关键词： Biomineralization Hydroxyapatite Crystal growth

Synthesis of high grade octahedron diamond through epitaxial growth

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中国有色金属学会会刊：英文版 1999年第3期9卷 477-480页

作者： Yi Jianhong(易建宏) National key laboratory for powder metallurgy, central south university of Technology, changsha 410083, P.R. china Cent S Univ Technol Natl Key Lab Powder Met Changsha 410083 Peoples R China

The work was based on the relationship between the crystal structure and parameters of diamonds in the synthetic process, in which Ni Mn C powder catalyst was used. At first, the diamond crystals nucleated in a cubic octahedron morphology through controlling such synthetic parameters as temperature and pressure in a parameter region where cubic octahedron ctystals can be obtained. Then the diamond nuclei grew epitaxially into crystals with a perfect octahedron morphology through increasing the synthesis temperature and decreasing the synthesis pressure in a parameter region where octahedron crystals can be obtained.

关键词： high grade diamond eqitaxial growth

INJECTION MOLDED TUNGSTEN HEAVY ALLOY

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中国有色金属学会会刊：英文版 1998年第4期8卷 45-50页

作者： Li Yimin, Qu Xuanhui, Li Zhilin and Huang Baiyun state key laboratory for powder metallurgy, central south university of Technology, changsha 410083, P. R. china state key laboratory for powder metallurgy Central South University of Technology Changsha 410083 China

ＩＮＴＲＯＤＵＣＴＩＯＮＭｅｔａｌＩｎｊｅｃｔｉｏｎＭｏｌｄｉｎｇ（ＭＩＭ），ｗｈｉｃｈｉｓｄｅｒｉｖｅｄｆｒｏｍｐｌａｓｔｉｃｉｎｊｅｃｔｉｏｎｍｏｌｄｉｎｇ，ｉｓａｋｉｎｄｏｆｎｅｗｌｙｄｅｖｅｌｏｐｅｄｐｏｗｄ... 详细信息

ＩＮＴＲＯＤＵＣＴＩＯＮＭｅｔａｌＩｎｊｅｃｔｉｏｎＭｏｌｄｉｎｇ（ＭＩＭ），ｗｈｉｃｈｉｓｄｅｒｉｖｅｄｆｒｏｍｐｌａｓｔｉｃｉｎｊｅｃｔｉｏｎｍｏｌｄｉｎｇ，ｉｓａｋｉｎｄｏｆｎｅｗｌｙｄｅｖｅｌｏｐｅｄｐｏｗｄｅｒｍｅｔａｌｕｒｇｙｆｏｒｍｉｎ...

关键词： injection molding heavy alloy powder loading

Fabrication and properties of binder for powder extrusion molding

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Rare Metals 2003年第2期22卷 98-102页

作者： ZHOUJicheng HUANGBaiyun SchoolofPhysicsScienceandTechnology CentralSouthUniversityChangsha410083China statekeylaboratoryforpowdermetallurgy CentralSouthUniversityChangsha410083China

By optimizing formulation and fabrication methods, a new binder forplasticizing powder extrusion molding of hard metal, with excellent integrated properties anduniform distribution characters, has been developed. Thermal debonding mechanism and the extrudingtheological behaviours have been studied. The technology of fabrication of binder and thermaldebonding process have also been investigated. Using the novel binder, the hard-metalextrusion-molding rods with diameter up to 25mm, have been manufactured.

关键词： powder metallurgy binder powder extrusion molding thermal debonding rheology hard metal

SUPERPLASTIC BEHAVIOR OF HOT-FORGED TiAl-BASED ALLOY

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中国有色金属学会会刊：英文版 1999年第2期9卷 74-76页

作者： Deng Zhongyong, Huang Baiyun , He Yuehui and Liu Yong state key laboratory for powder metallurgy, central south university of Technology, changsha 410083, P. R. china central south Univ of Technology Changsha China

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｉＡｌｂａｓｅｄａｌｏｙｓａｒｅｃｏｎｓｉｄｅｒｅｄｔｈｅｍｏｓｔｆａｖｏｒａｂｌｅｃａｎｄｉｄａｔｅｓａｓａｄｖａｎｃｅｄｓｔｒｕｃｔｕｒａｌｍａｔｅｒｉａｌｓｆｏｒａｅｒｏｓｐａｃ... 详细信息

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｉＡｌｂａｓｅｄａｌｏｙｓａｒｅｃｏｎｓｉｄｅｒｅｄｔｈｅｍｏｓｔｆａｖｏｒａｂｌｅｃａｎｄｉｄａｔｅｓａｓａｄｖａｎｃｅｄｓｔｒｕｃｔｕｒａｌｍａｔｅｒｉａｌｓｆｏｒａｅｒｏｓｐａｃｅａｐｐｌｉｃａｔｉｏｎｂｅｃａｕ...

关键词： TiAldeformationsuperplasticitystrain rate