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Effects of heat treatment on the properties of powder injection molded AlN ceramics

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Rare Metals 2008年第1期27卷 70-73页

作者： DU Xueli QIN Mingli Akhtar Farid FENG Peizhong QU Xuanhui Institute of powder metallurgy University of Science and Technology Beijing Beijing 100083 China School of Materials Science andEngineering Tianjin University of Technology Tianjin 300191 China

The effects of two different heat-treatment atmospheres,nitrogen atmosphere and reducing nitrogen atmosphere with carbon,on the properties of Y2O3-doped aluminum nitride（AlN） ceramics were *** AlN powder as a raw material was synthesized by self-propagating high-temperature synthesis（SHS） and compacts were fabricated by employing powder injection molding *** polymer-wax binder consisted of 60 wt.% paraffin wax（PW）,35 wt.% polypropylene（PP）,and 5 wt.% stearic acid（SA）.After the removal of binder,specimens were sintered at 1850°С in nitrogen atmosphere under atmospheric *** improve the thermal conductivity,sintered samples were *** result reveals that the heat-treatment atmosphere has significant effect on the properties and secondary phase of AlN *** thermal conductivity and density of AlN ceramics reheated in nitrogen gas are 180 W·m^-1·K^-1 and 3.28 g·cm^-3 and the secondary phase is yttrium *** the sample reheated in reducing nitrogen atmosphere with carbon,the thermal conductivity and density are 173 W·m^-1·K^-1 and 3.23 g·cm^-3,respectively,and the secondary phase is YN.

关键词： powder injection molding AIN ceramics heat treatment thermal conductivity

Effects of boron on the microstructure and thermal properties of Cu/diamond composites prepared by pressure infiltration

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International Journal of Minerals,metallurgy and Materials 2011年第4期18卷 472-478页

作者： Ye-ming Fan Hong Guo Jun Xu Ke Chu Xue-xin Zhu Cheng-chang Jia Non-Ferrous Metal Processing Division General Research Institute for Non-ferrous Metals Beijing 100088 China Institute of powder metallurgy University of Science and Technology Beijing Beijing 100083 China

Diamond reinforced copper（Cu/diamond） composites were prepared by pressure infiltration for their application in thermal management where both high thermal conductivity and low coefficient of thermal expansion（CTE） are *** were characterized by the microstructure and thermal properties as a function of boron content,which is used for matrix-alloying to increase the interfacial bonding between the diamond and *** obtained composites show high thermal conductivity（660 W/（m·K）） and low CET（7.4×10-6 K-1） due to the formation of the B13C2 layer at the diamond-copper interface,which greatly strengthens the interfacial *** property measurements indicate that in the Cu-B/diamond composites,the thermal conductivity and the CTE show a different variation trend as a function of boron content,which is attributed to the thickness and distribution of the interfacial carbide *** CTE behavior of the present composites can be well described by Kerner＇s model,especially for the composites with 0.5wt% B.

关键词： composite materials pressure infiltration thermal conductivity coefficient of thermal expansion

Precipitation behavior of γ′ phase in superalloy FGH96 under interrupted cooling test

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Rare Metals 2013年第6期32卷 560-563页

作者： Heng-San Liu Lin Zhang Xin-Bo He Xuan-Hui Qu Zhou Li Guo-Qing Zhang beijing Key Laboratory for powder metallurgy and Particulate Materials University of Science and Technology Beijing National Key Laboratory of High Temperature Structural Materials Beijing Institute of Aeronautical Materials

The precipitation behavior of γ′ phase,under various interrupt cooling tests after 1170℃,solution treatment was *** results indicate that the size of secondary γ′ precipitates increases with the decrease of interrupt temperature,and the shape changes from spherical to butterfly *** fine tertiary γ′ can form either during the post cool air quenching at high interrupt-temperatures,or during the specified 5℃ *** quenching at high temperatures cannot suppress further nucleation of tertiary γ′ phase.

关键词： powder metallurgy Ni-base superalloy Interrupt cooling Precipitation

Viscosity and surface tension of CaF_(2)-CaO-Al_(2)O_(3)-based slag with varying SiO_(2) and B_(2)O_(3) contents for ESR of rotor steel

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Journal of Iron and Steel Research International 2023年第1期30卷 74-81页

作者： Yi Huang Cheng-bin Shi Xiu-xiu Wan Yu-jing Liang Jing Li Shu-jie Liu State Key Laboratory of Advanced metallurgy University of Science and Technology BeijingBeijing 100083China Xingtai Shuzhi metallurgy Technology co. Ltd.Xingtai 054027HebeiChina

The effect of SiO_(2) and B_(2)O_(3) on viscosity and surface tension of CaF_(2)-CaO-Al_(2)O_(3)-MgO-SiO_(2)-B_(2)O_(3) slag designed for electroslag remelting of rotor steel was *** viscosity of the slag melts increases with increasing the SiO_(2) content from 0.37 to 8.03 mass%,and the viscous activation energy increases from 54.21 to 58.49 kJ/*** B_(2)O_(3) content of the slag from 0 to 3.62 mass%exhibits a similar effect on the viscosity,and the activation energy increases from 47.30 to 55.71 kJ/*** increase in the viscosity and activation energy for viscous flow of slag is attributed to the enhanced polymerization degree of slag melts network with increasing either SiO_(2) or B_(2)O_(3) *** surface tension of slag melts decreases with increasing *** surface tension of slag melts decreases with increasing either SiO_(2) or B_(2)O_(3) content,which is originated from the increase in the polymerization degree and the decrease in the CaO content of the slag.

关键词： High-fluoride slag Structure Viscosity Surface tension Activation energy

High temperature oxidation behaviors of Ti-Cr alloys with Laves phase TiCr_2

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中国有色金属学会会刊：英文版 2002年第2期12卷 200-203页

作者：肖平安曲选辉雷长明祝宝军秦明礼敖晖黄培云 State Key Laboratory for powder metallurgy Central South University Changsha 410083 ChinaDepartment of Automobile and Electromechanical Engineering Changsha Communications University Changsha 410076 China State Key Laboratory for powder metallurgy Central South University Changsha 410083 ChinaSchool of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083 China State Key Laboratory for powder metallurgy Central South University Changsha 410083 China

The high temperature oxidation behaviors of Ti Cr alloys containing 18% ～ 35% Cr with Laves phase TiCr 2 were investigated at 650 ～ 780?℃ for exposure up to 104?h. The results reveal that chromium content has critical significance to the oxidation resistance of the alloys. The scaling rates of the alloys with less than 21% Cr are higher than those measured for pure titanium, but for the alloys with more than 26% Cr their scaling rate is lowered by 1～2 times, under the same oxidizing conditions. Both an external and an internal oxidation layers were observed. The oxidation resistance enhancement by chromium alloying is contributed to the formation of a continuous and compact chromic oxide interleaf in the scale. Oxidation temperature significantly affects the scaling rates of Ti Cr alloys, and the mass gain is doubled with a temperature change from 650?℃ to 700?℃ or from 700?℃ to 780?℃, for the same exposure duration. TiCr 2 shows no negative influence on the high temperature oxidation resistance of the alloys.

关键词：拉夫斯相钛铬合金高温氧化 TiCr2

Phase transformation of nano-grained W(co, C) composite powder and its phase constitute

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Journal of Central South University of Technology 2006年第6期13卷 603-607页

作者：曹顺华蔡志勇周建华李炯义林信平 State Key Laboratory of powder metallurgy Central South University

A new process of WC-co cemented carbide was developed by using nano-grained W（co, C） composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion（XRD）, differential thermal analysis （DTA）, thermo-gravimetrie （TG） analysis and coercive forces of the sintered samples were adopted to analyze the phase transformation and constitution, and the microstructures of sintered samples were characterized by scanning electron microscopy（SEM）. The results show that the as-milled powders are transformed into transitional phases W2C and η （co3W3C or co6W6C） during sintering, and finally transformed into WC and co phases completely at 1 250℃ for 30 min, and a large number of fibrous WC grains with about 1.2μm in length and 100 nm in radial dimension are formed in the sintered body at 1 300 ℃.

关键词： cemented carbide phase transformation high-energy ball milling fibrous WC grain

Pore opening and binder flow during initial stage of thermal debinding in MIM

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中国有色金属学会会刊：英文版 2003年第5期13卷 1194-1198页

作者：赵利刚李益民 State Key Laboratory for powder metallurgy Central South University Changsha 410083China State Key Laboratory for powder metallurgy Central South University Changsha 410083ChinaHunan Injection Hi Tech Ltd Changsha 410083China

Pore opening and binder flow during the initial stage of thermal debinding in metal injection molded parts was investigated. Scaning electron microscopy(SEM) pictures of 316 L stainless steel parts using wax based binder show that small particles will move to the surface with the process of debinding. SEM pictures of different mass loss rate specimens indicate that initial pores will emerge when as little as 4% binder removes. During the initial stage of thermal debinding, vapor tension varies in different place due to the difference of curvature. Thus more binders will be removed in places with smaller cavity between metal powders, and in these places small openings emerge.

关键词：金属注射成型热结合胶结剂流动注模成型

Achieving integrated capture and reduction of co_(2):A promising electrocatalyst

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Journal of Materials Science & Technology 2023年第34期165卷 235-243页

作者： Mengjie Liu Longsheng Zhan Yuchao Wang Xin Zhao Jiao Wu Danni Deng Jiabi Jiang Xinran Zheng Yongpeng Lei State Key Laboratory of powder metallurgy Central South UniversityChangsha 410083China

To realize the goal of carbon peaking and carbon neutrality,co_(2) capture and utilization technology is becoming increasingly ***,the low efficiency and complex processes limit its large-scale *** utilization technology of co_(2),electrochemical co_(2) reduction reaction(co_(2)RR)has attracted interest,attributing to the use of clean energy and the final product of value-added *** construction of catalysts with integrated co_(2) capture and reduction ability is expected to bridge the gap between co_(2) capture and conversion,achieving the direct utilization of flue gas,reducing costs,and simplifying ***` this in mind,we give this review to introduce the problems of lowconcentration co_(2)RR and the significance of coupled co_(2) capture/conversion electrocatalysts in addressing the emission of industrial flue gas ***,the regulation strategies,including functional group modification,co-catalytic effect,and catalysts-impurities interaction,which affected the co_(2) capture and electroreduction capacity towards catalysts were summarized and ***,the challenges and perspectives about the design for linked co_(2) capture/conversion processes were *** review will provide new insight into the building of multifunctional catalysts for co_(2) conversion.

关键词： co_(2)capture and electroreduction Electrocatalyst Functional group co-catalytic effect Catalysts-impurities interaction

Pyrolysis of furfural-acetone resin as matrix precursor for new carbon materials

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Journal of Central South University of Technology 2008年第6期15卷 753-756页

作者：夏伦刚张红波熊翔左劲旅尹健 State Key Laboratory of powder metallurgy Central South University

In order to increase the understanding of the pyrolysis mechanism, Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry-mass spectrometric coupling technique (TG-MS) were used to study the pyrolysis behavior of furfural-acetone resin used for new carbon materials. The curing and carbonization mechanisms of furfural-acetone resin were mainly investigated; structural changes and volatile products evolved during pyrolysis were analyzed. The results indicate that, during pyrolysis of furfural-acetone resin adding 7% (mass fraction) phosphorous acid as curing agent, the rupture of C—O bond in the five-membered heterocycle firstly takes place to release oxygen atoms and then does the C—H bond, which enable the molecular chain to cross-link and condense, then lead to the formation of three dimensional networking structure. With the increase of pyrolyzing temperature, the scission of methyl and the opening of furan ring are generated. As a result, the recomposition of molecular chain structure is generated and a hexatomic fused ring containing double bonds is built. The main volatile products during pyrolysis of furfural- acetone resin are H2O, and a small mount of co, co2 and CH4. At elevated temperatures, dehydrogenation takes place and hydrogen gas is evolved.

关键词： new carbon materials furfural-acetone resin pyrolysis volatile products