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An improved sodium silicate binder modified by ultra-fine powder materials 被引量:5
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作者 WANG Ji-na FAN Zi-tian +2 位作者 WANG Hua-fang DONG Xuan-pu HUANG Nai-yu 《China Foundry》 SCIE CAS 2007年第1期26-30,共5页
This paper presents a new method of modifying sodium silicate binder with ultra-fine powders. The sodium silicate binder modified by ultra-fine powder A and the organic B can reduce the addition amount of the binder. ... This paper presents a new method of modifying sodium silicate binder with ultra-fine powders. The sodium silicate binder modified by ultra-fine powder A and the organic B can reduce the addition amount of the binder. The results indicate that the 24 h strength has increased by 39.9% at room temperature and the residual strength has decreased by 30.7% at 800℃, compared to the conventional sodium silicate. An available material to improve the moisture resistance was also found by adding about 2% more inorganic C, and it can increase the moist strength by 20%. In the end, the microanalyses are given to explain the modifying machanism, i. e., the ultra-fine powder A can refine the sodium silicate binder to avoid holes in the binder bond, which can increase the 24 h strength at room temperture, and can lead to more cracks in the bond after the molding sand is heated to 800℃. This is because of the stress caused by the new eutectic complex of modified sodium silicate binder. 展开更多
关键词 sodium silicate binder modification ultra-fine powder materials bonding strength moisture resistance COLLAPSIBILITY
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Magnetic modification of diamagnetic agglomerate forming powder materials
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作者 Ivo Safarik Eva Baldikova +1 位作者 Kristyna Pospiskova Mirka Safarikova 《Particuology》 SCIE EI CAS CSCD 2016年第6期169-171,共3页
A simple method for the magnetic modification of various types of powdered agglomerate forming dia- magnetic materials was developed. Magnetic iron oxide particles were prepared from ferrous sulfate by microwave assis... A simple method for the magnetic modification of various types of powdered agglomerate forming dia- magnetic materials was developed. Magnetic iron oxide particles were prepared from ferrous sulfate by microwave assisted synthesis. A suspension of the magnetic particles in water soluble organic solvent (methanol, ethanol, propanol, isopropyl alcohol, or acetone) was mixed with the material to be modified and then completely dried at elevated temperature. The magnetically modified materials were found to be stable in water suspension at least for 2 months. 展开更多
关键词 Magnetic modification Magnetic separation powdered material Magnetic iron oxide Microwave assisted synthesis
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Spheroidization of molybdenum powder by radio frequency thermal plasma 被引量:7
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作者 Xiao-ping Liu Kuai-she Wang +2 位作者 Ping Hu Qiang Chen Alex A.Volinsky 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2015年第11期1212-1218,共7页
To control the morphology and particle size of dense spherical molybdenum powder prepared by radio frequency(RF) plasma from irregular molybdenum powder as a precursor, plasma process parameters were optimized in th... To control the morphology and particle size of dense spherical molybdenum powder prepared by radio frequency(RF) plasma from irregular molybdenum powder as a precursor, plasma process parameters were optimized in this paper. The effects of the carrier gas flow rate and molybdenum powder feeding rate on the shape and size of the final products were studied. The molybdenum powder morphology was examined using high-resolution scanning electron microscopy. The powder phases were analyzed by X-ray diffraction. The tap density and apparent density of the molybdenum powder were investigated using a Hall flow meter and a Scott volumeter. The optimal process parameters for the spherical molybdenum powder preparation are 50 g/min powder feeding rate and 0.6 m^3/h carrier gas rate. In addition, pure spherical molybdenum powder can be obtained from irregular powder, and the tap density is enhanced after plasma processing. The average size is reduced from 72 to 62 μm, and the tap density is increased from 2.7 to 6.2 g/cm^3. Therefore, RF plasma is a promising method for the preparation of high-density and high-purity spherical powders. 展开更多
关键词 powder materials molybdenum radio frequency plasma spheroidization processing parameters
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IGNITING SHS BY LASER AND ITS APPLICATION TO SELECTIVE LASER SINTERING OF METALLIC POWDER MATERIAL 被引量:1
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作者 Y.S.Shi S.C.Chen X.L.Lu S.H.Huang 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2004年第5期694-704,共11页
How to directly fabricate metallic functional parts with selective laser sintering (SLS) process is a potential technique that scientists are researching. Existent problems during directly fabricating metal part by us... How to directly fabricate metallic functional parts with selective laser sintering (SLS) process is a potential technique that scientists are researching. Existent problems during directly fabricating metal part by use of SLS are analyzed. For the sake of solving the problems, a new idea of adding self-propagating high-temperature synthesis (SHS) material into metallic powder material to form new type of SLS metallic powder material is put forward. This powder material can release controllable amount of heat during its interaction with the laser beam energy to reduce the requirement to laser power during directly sintering metallic part, to prolong the time of metallic liquid phase existing, and to improve the intensity and accuracy of SLS part. For this reason, SHS material′s interaction with the CO2 laser beam energy is researched, which proves that CO2 laser beam energy may instantly ignite SHS reaction. On the basis of the above-mentioned researches, the effect of sintering the metal powder material mixing SHS material with CO2 laser is also researched, which shows: there is an optimal blending ratio of various material in the new metallic powder material. Under the optimal blending ratio and SLS process parameters, this new metallic powder material can indeed release amount of heat and SHS reaction may be controlled within the laser sintering. This research result makes it possible that the metallic part is directly sintered with small CO2 laser (less than 50W), which may greatly reduce the volume, cost and running expenditure of SLS machine, be propitious to application. 展开更多
关键词 selective laser sintering (SLS) self-propagating high-temperaturesynthesis (SHS) ignition time metallic powder material metallic part
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Preparation of FVS1212/FVS0812 materials and its mechanical properties 被引量:1
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作者 谭敦强 黎文献 +2 位作者 肖于德 周浪 陈伟 《Journal of Central South University of Technology》 EI 2005年第5期503-506,共4页
FVS1212/FVS0812 material was prepared by adding FVS1212 powder into FVS0812 powder. The structure and mechanical properties of materials were studied by means of X-Ray, tensile measurement, OM and SEM. The results sho... FVS1212/FVS0812 material was prepared by adding FVS1212 powder into FVS0812 powder. The structure and mechanical properties of materials were studied by means of X-Ray, tensile measurement, OM and SEM. The results show that adding proper content FVS1212 powders can improve the tensile strength of FVS0812 aluminum at room temperature and elevated temperature, and that the elongation of FVS1212/FVS0812 material is better than that of FVS1212 aluminum. 展开更多
关键词 powder metallurgy FVS0812/FVS1212 material elevated temperature strength
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Multi-diffused Reflection Spectroscopy of Rare Earths Doped LaOCl Powder Samples and the Calculation of Quantum Efficiency
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作者 蒋雪茵 张志林 许少鸿 《Journal of Rare Earths》 SCIE EI CAS CSCD 1995年第2期94-98,共5页
The excitation and emission spectra, the relaxation time of principal spectral lines and multi-diffused reflection spectra in LaOCl: Er, LaOCl: Ho powder samples were measured. The diffused absorption spectrum was der... The excitation and emission spectra, the relaxation time of principal spectral lines and multi-diffused reflection spectra in LaOCl: Er, LaOCl: Ho powder samples were measured. The diffused absorption spectrum was derived from the multi-diffused reflection spectrum. According to Judd-Ofelt theory,the intensity parameters, radiative transition probabilities and quantum efficiencies of luminescence emission were calculated. Then comparison with erbium and holmium doped floride glass and other matrices were made. 展开更多
关键词 powdered material Multi-diffused reflection Diffused reflection absorption spectrum Quantum efficiency
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Optimization of Processing Parameters for Laser Powder Deposition using Finite Element Method
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作者 付垚 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2010年第5期832-837,共6页
In order to investigate the effects of powder materials and processing parameters on thermal and stress field during laser powder deposition (LPD), a finite element model was developed with the help of ANSYS softwar... In order to investigate the effects of powder materials and processing parameters on thermal and stress field during laser powder deposition (LPD), a finite element model was developed with the help of ANSYS software. The finite element model was verified by the comparison between the experimental results and computed results. Then LPD processes with different powder materials and processing parameters were simulated by using the FE model. The results show that less difference of thermal conductivity and thermal expansion coefficient between powder material and substrate material produces lower residual stress; higher laser power, laser scanning speed and smaller laser beam diameter can lead higher peak temperature and higher residual stress. The research opens up a way to rational selection of the powder materials and processing parameters for ensured quality. 展开更多
关键词 laser powder deposition thermal field stress field powder material processing parameters
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Sintering Effect on the Performance of Tungsten-copper Powder Liner
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作者 高永宏 GU Xiaohui LIU Tiansheng 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2012年第6期1133-1136,共4页
In order to study the properties of high-temperature sintered tungsten-copper powder shaped charge liner, the tungsten powder and copper powder, whose particle size is below 20 μm, were chosen as the main material. T... In order to study the properties of high-temperature sintered tungsten-copper powder shaped charge liner, the tungsten powder and copper powder, whose particle size is below 20 μm, were chosen as the main material. The mixed powder were directly pressed into the desired shape of the charge liner by the top direct-pressure way. The microscopic morphology of the spinning shaped charge liner, and the particle properties of the copper and tungsten powder were studied with scanning electron microscopy. The experimental results showed that the irregular copper powder and regular tungsten powder both are effectively and high- temperature sintering, which can improve the compactness of the powder liner effectively. The wall thickness and density of the no sintered and sintered liner were tested, showing that sintering thinned down the wall thickness and improved the density. The penetration depth of no sintered powder liner, sintered powder liner and the spinning copper plate liner were respectively tested in different standoff, showing that the penetration properties of sintered powder liner are well. 展开更多
关键词 powder material SINTERING MICROSTRUCTURE penetration effect
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Modification of Powder Compaction Equation of Kawakita
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作者 葛荣德 《Rare Metals》 SCIE EI CAS CSCD 1993年第3期229-231,共3页
Based on an analysis of the validity of the powder compaction equation of Kawakita,a modified compaction equation is proposed.It is shown by the statistical analysis on the experimental compaction data of various powd... Based on an analysis of the validity of the powder compaction equation of Kawakita,a modified compaction equation is proposed.It is shown by the statistical analysis on the experimental compaction data of various powders that in most cases the proposed equation provides a better description of the compaction data than Kawakita's equation,especially in the cases of the compaction of hard material powders. 展开更多
关键词 powder compaction equation Statistical analysis Modified equation Hard material powder
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WEAR AND SEALING CHARACTERISTICS OF ENGINE VALVE GUIDE 被引量:2
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作者 Qu Shengguan Xia Wei Han Lifa Xiao Zhiyu Chen Weiping LiYuanyuan 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2005年第3期434-438,共5页
A novel powder metallurgy (P/M) material with high wear resistance is developed in order to decrease the wear and lubricant-leakage of a diesel engine valve guide. The friction and wear tests of this material are co... A novel powder metallurgy (P/M) material with high wear resistance is developed in order to decrease the wear and lubricant-leakage of a diesel engine valve guide. The friction and wear tests of this material are conducted. It indicates that the wear resistance of the newly developed P/M material has been improved and much better than that of the formerly used alloy steel. Moreover, three different sealing structures are designed and theoretically analyzed with respect to the characteristic of hydrodynamic sealing. Through comparative experiments of component leakage and engine run-in for different valve guide structures, it proves that the structure with a machined sealing groove but not installed with a seal-ring cannot only reduce the specific lubricant consumption (SLC) of cylinder head, but also decrease the wear of valve stern and valve guide. 展开更多
关键词 Engine valve guide powder metallurgy material Friction and wear Sealing
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Solution combustion synthesis of Fe-Ni-Y_2O_3 nanocomposites for magnetic application
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作者 刘烨 秦明礼 +4 位作者 章林 贾宝瑞 陈鹏起 张德志 曲选辉 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第1期23-29,共7页
Fe-Ni-Y2O3 nanocomposites with uniform distribution of fine oxide particles in the gamma Fe Ni matrix were successfully fabricated via solution combustion followed by hydrogen reduction. The morphological characterist... Fe-Ni-Y2O3 nanocomposites with uniform distribution of fine oxide particles in the gamma Fe Ni matrix were successfully fabricated via solution combustion followed by hydrogen reduction. The morphological characteristics and phase transformation of the combusted powder and the Fe-Ni-Y2O3 nanocomposites were characterized by XRD, FESEM and TEM.Porous Fe-Ni-Y2O3 nanocomposites with crystallite size below 100 nm were obtained after reduction. The morphology, phases and magnetic property of Fe-Ni-Y2O3 nanocomposites reduced at different temperatures were investigated. The Fe-Ni-Y2O3 nanocomposite reduced at 900 °C has the maximum saturation magnetization and the minimum coercivity values of 167.41 A/(m2·kg)and 3.11 k A/m, respectively. 展开更多
关键词 nanocomposite powder solution combustion synthesis soft magnetic materials magnetic properties
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Mixing of particles and powders:Where next? 被引量:6
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作者 John Bridgwater 《Particuology》 SCIE EI CAS CSCD 2010年第6期563-567,共5页
Industrial mixers for powders and granular materials operate with no effective control of mixture quality and lack scientific design. The last twenty years have seen growth in understanding of mixing and mixers. Howev... Industrial mixers for powders and granular materials operate with no effective control of mixture quality and lack scientific design. The last twenty years have seen growth in understanding of mixing and mixers. However, research falls far short of what is needed for on-line characterisation of mixture quality. Secondly, although theoretical descriptions of a few mixer types have been reported, these fall far short of what is needed for equipment design. Two thrusts could revolutionise this situation. One is a scientific characterisation of mixer structure applicable to industrial scale as well as laboratory scale equipment; this is now within our grasp using digital imaging. The other is the development of ideas to overcome the restricted number of particles that can be used in the Distinct Element Method (DEM) for mixers. The goal should be to take the designer through a sequence of steps to the most appropriate mixer size, configuration and operating conditions for a given process duty. 展开更多
关键词 Design Granular materials Mixing Mixers powders Quality characterisation Quality measurement
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Leakage of nuclear material powder from pressure container through a small orifice
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作者 Longbo Liu Yanmin Wu +5 位作者 Yongyang Su Hanbing Tang Zhihong Zhang Ping Huang Lili Zhang Lixing Zhang 《Particuology》 SCIE EI CAS CSCD 2014年第3期117-123,共7页
Because of the radioactivity and toxic nature of nuclear materials, their containment within oxide matrices, encased in sealed containers, has been proposed as a suitable means for storage and transportation. However,... Because of the radioactivity and toxic nature of nuclear materials, their containment within oxide matrices, encased in sealed containers, has been proposed as a suitable means for storage and transportation. However, container failures because of cracks or small orifices present a major leakage risk for nuclear materials, consequently posing a significant hazard to the environment and human beings. In this study, terbium oxide powder was used as a nuclear material representative to examine the leakage of nuclear material powder through orifices located at the base of a pressure container. The dependence of the orifice diameter, the powder layer thickness, and the internal pressure of the container on the leakage mechanism and amount was examined. A simplified model correlating the dependence of the above-mentioned parameters to determine the utmost leakage amount was also developed based on the present results. The leakage of the nuclear material powder was assessed by measuring its concentration using an optical particle counter. The diameter of the orifice determined the powder leakage mechanism, which in turn influenced the amount of leakage produced. Comparison studies showed that unlike the changes in the differential pressure, the volume of the container has little effect on the leakage amount. Under sufficiently high internal pressures, the oxide powder can be released as a fine aerosol. The work is not only crucial from the nuclear safety aspect, but is also beneficial for the safe application of powder and nanoparticles. 展开更多
关键词 Nuclear materials powder Leakage Risk assessment
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Numerical analysis of enhanced mixing in a Gallay tote blender 被引量:4
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作者 Xinxin Ren Guangzheng Zhou +2 位作者 Ji xu Lijie Cui Wei Ge 《Particuology》 SCIE EI CAS CSCD 2016年第6期95-102,共8页
The mixing performance of a multi-bladed baffle inserted into a traditional Gallay tote blender is explored by graphic processing unit-based discrete element method software. The mixing patterns and rates are investig... The mixing performance of a multi-bladed baffle inserted into a traditional Gallay tote blender is explored by graphic processing unit-based discrete element method software. The mixing patterns and rates are investigated for a binary mixture, represented by two different colors, under several loading profiles. The baffle effectively enhances the convective mixing both in the axial and radial directions, because of the disturbance it causes to the initial flowing layer and solid-body zone, compared with a blender without a baffle. The axial mixing rate is affected by the gap between the baffle and the wall on the left and right sides, and an optimal blade length corresponds to the maximum mixing rate. However, the radial mixing rate increases with the blade length almost monotonically. 展开更多
关键词 powder mixing Tote blender Granular materials Discrete element method Simulation Baffle
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