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Preparation of RE-containing magnesium alloys via molten-salt-mediated magnesiothermic reduction 被引量:1
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作者 Zhimin Zhang Xuchen Lu Yan Yan 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第3期981-990,共10页
RE-containing magnesium alloys were prepared via molten-salt-mediated magnesiothermic reduction by using RE_(2)O_(3)(RE=Y,Nd and Gd)and Mg metal as raw materials.The thermomechanical analysis of the magnesiothermic re... RE-containing magnesium alloys were prepared via molten-salt-mediated magnesiothermic reduction by using RE_(2)O_(3)(RE=Y,Nd and Gd)and Mg metal as raw materials.The thermomechanical analysis of the magnesiothermic reduction reactions in molten salt was investigated.Then the molten-salt-mediated magnesiothermic reduction process was studied from three different perspectives.After that,the RE-containing magnesium alloy was characterized by using chemical analysis,XRD analysis and SEM analysis.The magnesiothermic reduction was a liquid-liquid reaction with relatively weak driving force.During the melting process and the magnesiothermic reduction process,magnesium metal and the obtained alloy went up and down as a whole in molten salt,which improved the process safety without introducing chloride inclusions.Meanwhile,the hydrolysis of the RECl_(3^(-))containing molten salt occurred at elevated temperature,which severely impeded the magnesiothermic reduction process.After the magnesiothermic reduction at 750°C for 2.0 h,the content of RE and the common impurity elements in the obtained RE-containing alloy met the both requirements of the commercial WE43A and WE43B. 展开更多
关键词 Magnesium alloy Rare earth Magnesiothermic reduction Molten salt
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Insight into the effect of gel drying temperature on the structure and desulfurization performance of ZnO/SiO_(2)adsorbents
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作者 Chao Yang Zhelin Su +3 位作者 Yeshuang Wang Huiling Fan Meisheng Liang Zhaohui Chen 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2023年第4期233-241,共9页
A series of ZnO/SiO_(2) adsorbents were prepared by a sol-gel method using tetraethyl orthosilicate,ethylene glycol(EG)and nitrates as precursors.The effect of gel drying temperature on the structure and desulfurizati... A series of ZnO/SiO_(2) adsorbents were prepared by a sol-gel method using tetraethyl orthosilicate,ethylene glycol(EG)and nitrates as precursors.The effect of gel drying temperature on the structure and desulfurization performance of the adsorbents were investigated in detail.It is found that the low drying temperature led to a weak interaction among EG,Si AOH/H_(2)O and the nitrates in the gel system,which caused the oxidation of EG by NO3-and formed zinc glyoxylate complex during the gel calcination process,whereas this oxidation process also occurred at a high drying temperature during the gel drying process.The formed zinc glyoxylate complex promoted the generation of monodentate carbonate on the surface of Zn O,which resulted in the inferior desulfurization performance of adsorbents despite they have smaller Zn O nanoparticles.The gel dried at 120°C formed the hydrogen bonds between EG and Si AOH/H_(2)O and a strong interaction between zinc oxo-clusters and NO3-was also found in the gel system,which avoided the oxidation of EG by NO3-during the preparation process and the Zn O nanoparticles with sizes of 6 nm were formed by a combustion method.The adsorbent affords a highest sulfur capacity of 104.9 mg·g^(-1) in this case.In addition,the gel drying temperature has a significant influence on the textural properties of the adsorbents except their surface area. 展开更多
关键词 Sol-gel method Drying temperature H_(2)S removal Zinc-silica composites Hydrogen bonds
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Extraction of scandium from red mud by modified activated carbon and kinetics study 被引量:20
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作者 ZHOU Hualei LI Dongyan +1 位作者 TIAN Yajun CHEN Yunfa 《Rare Metals》 SCIE EI CAS CSCD 2008年第3期223-227,共5页
Activated carbon (AC) was modified by tri-butyl phosphate (TBP) for selectively extracting scandium from red mud and characterized by BET (Brunauer-Emmett-Teller) surface area. The modified AC had a preferential... Activated carbon (AC) was modified by tri-butyl phosphate (TBP) for selectively extracting scandium from red mud and characterized by BET (Brunauer-Emmett-Teller) surface area. The modified AC had a preferential adsorption to scandium. The influences of adsorbent dos- age, adsorption temperature, and time on adsorption capacity and selectivity to scandium were examined. An optimum adsorbent dosage (-6.25 g/L), adsorption temperature (308 K), and adsorption time (40 min) were figured out. A pseudo-second-order kinetics model was employed for describing the adsorption process of scandium. 展开更多
关键词 modified activated carbon ADSORPTION red mud SCANDIUM
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Study on Kinetics of Iron Oxide Reduction by Hydrogen 被引量:11
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作者 HOU Baolin ZHANG Haiying +1 位作者 LI Hongzhong ZHU Qingshan 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第1期10-17,共8页
Kinetics parameters of iron oxide reduction by hydrogen were evaluated by the isothermal method in a differential micro-packed bed. Influence of external diffusion, internal diffusion and heat transfer on the intrinsi... Kinetics parameters of iron oxide reduction by hydrogen were evaluated by the isothermal method in a differential micro-packed bed. Influence of external diffusion, internal diffusion and heat transfer on the intrinsic reaction rate was investigated and the conditions free of internal and external diffusion resistance have been determined. In the experiments, in order to correctly evaluate the intrinsic kinetics parameters for reducing Fe203 to Fe3O4, the reaction temperatures were set between 440 ℃ and 490 ℃. However, in order to distinguish the reduction of Fe304 to FeO from that of FeO to Fe, the reaction temperature in the experiment was set to be greater than 570 ℃. Intrinsic kinetics of iron oxide reduction by hydrogen was established and the newly established kinetic models were validated by the experimental data. 展开更多
关键词 isothermal method reduction kinetics iron oxide packed bed hydrogen reduction
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Effect of acidic surface functional groups on Cr(Ⅵ) removal by activated carbon from aqueous solution 被引量:7
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作者 ZHOU Hualei CHEN Yunfa 《Rare Metals》 SCIE EI CAS CSCD 2010年第3期333-338,共6页
The activated carbon with high surface area was prepared by KOH activation.It was further modified by H2SO4 and HNO3 to introduce more surface functional groups.The pore structure of the activated carbons before and a... The activated carbon with high surface area was prepared by KOH activation.It was further modified by H2SO4 and HNO3 to introduce more surface functional groups.The pore structure of the activated carbons before and after modification was analyzed based on the nitrogen adsorption isotherms.The morphology of those activated carbons was characterized using scanning electronic microscopy (SEM).The surface functional groups were determined by Fourier transform infrared spectroscopy (FTIR).The quantity of those groups was measured by the Boehm titration method.Cr(VI) removal by the activated carbons from aqueous solution was investigated at different pH values.The results show that compared with H2SO4,HNO3 destructs the original pore of the activated carbon more seriously and induces more acidic surface functional groups on the activated carbon.The pH value of the solution plays a key role in the Cr(VI) removal.The ability of reducing Cr(VI) to Cr(III) by the activated carbons is relative to the acidic surface functional groups.At higher pH values,the Cr(VI) removal ratio is improved by increasing the acidic surface functional groups of the activated carbons.At lower pH values,however,the acidic surface functional groups almost have no effect on the Cr(VI) removal by the activated carbon from aqueous solution. 展开更多
关键词 activated carbon surface functional groups REMOVAL MODIFICATION chromium(VI)
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Reduction mechanism of natural ilmenite with graphite 被引量:12
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作者 王玉明 袁章福 +3 位作者 郭占成 谭强强 李肇毅 姜伟忠 《中国有色金属学会会刊:英文版》 EI CSCD 2008年第4期962-968,共7页
Reduction of Bama ilmenite concentrate containing 49.78% TiO2 and 27.96% total Fe by graphite was studied using thermogravimetric analysis system under argon gas ambient from 850 to 1 400 ℃. The reduction degree of B... Reduction of Bama ilmenite concentrate containing 49.78% TiO2 and 27.96% total Fe by graphite was studied using thermogravimetric analysis system under argon gas ambient from 850 to 1 400 ℃. The reduction degree of Bama ilmenite is enhanced with increasing temperature and the molar ratio of carbon to oxygen, and the reaction rate varies with temperature and reduction time simultaneously. The phase transformation, chemical composition, microstructure and morphology of reduced samples were investigated by using X-ray diffractometry, scanning electron microscopy, and energy disperse spectroscopy, respectively. The high content of impurities in Bama ilmenite evidently bates the reduction of ilmenite. Forming the enrichment zone of manganese prevents complete reduction of Fe2+. The reduction products are mostly reduced iron, rutile, reduced rutiles, Ti3O5 and pseudobrookite solid solution. The reduction kinetics was also discussed. The results show that the reduction temperature is a key factor to control reaction rate. 展开更多
关键词 钛铁矿 还原机制 热重分析法 杂质 动力学 石墨
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Synthesis, characterization and catalytic methanation performance of modified kaolin-supported Ni-based catalysts 被引量:3
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作者 Jiao Liu Chuanyue Zheng +1 位作者 Junrong Yue Guangwen Xu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2019年第12期2953-2959,共7页
Kaolin as a raw material for mesoporous support was firstly modified by calcination,acid treatment,and then was used to prepare nickel catalysts.The amount of alumina which was activated in kaolin during thermal treat... Kaolin as a raw material for mesoporous support was firstly modified by calcination,acid treatment,and then was used to prepare nickel catalysts.The amount of alumina which was activated in kaolin during thermal treatment and then leached out in the acid was different.XRD pattern of the kaolin calcined at 600°C or 900°C exhibited only the diffraction peaks for amorphous silica and quartz while that calcined at 1100°C showed obvious peaks forγ-Al2 O3.Therefore,the nickel-based catalysts exhibited different physic-chemical properties.Atmospheric syngas methanation over the catalysts clarified an activity order of CA-1100 N CA-900 N CA-1400 N CA-600 N KA≈0 at temperatures of 350–650°C and a space velocity of 120 L·g-1·h-1.Metallic nickel with small diameter which has medium interaction with the modified kaolin and is well dispersed on the support would have reasonably good activity and carbon-resistance for syngas methanation. 展开更多
关键词 METHANATION KAOLIN CATALYST CATALYST support LEACHING
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Features of the Excess Adsorption Isotherms of High-Pressure Methane Adsorption on Coal and Simulation Model 被引量:3
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作者 CUI Yongjun ZHANG Dengfeng +4 位作者 ZHANG Qun LIN Weigang SONG Wenli LI Yuhui JIANG Wenping 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2010年第6期1547-1554,共8页
Four coal samples of different ranks are selected to perform the adsorption measurement of high-pressure methane(CH4).The highest equilibrium pressure of the measurement exceeds 20 MPa. Combined with the measuring r... Four coal samples of different ranks are selected to perform the adsorption measurement of high-pressure methane(CH4).The highest equilibrium pressure of the measurement exceeds 20 MPa. Combined with the measuring results and theoretical analyses,the reasons for the peak or the maximum adsorption capacity appearing in the excess adsorption isotherms are explained.The rules of the peak occurrence are summarized.And then,based on the features of coal pore structure,the adsorption features of high-pressure gas,the microcosmic interaction relationship of coal surface and CH4 molecule,and the coalbed methane reservoir conditions,three theoretical assumptions on the coal adsorption high-pressure CH_4 are suggested.Thereafter,on the basis of these theoretical assumptions,the Ono-Kondo lattice model is processed for simplification and deformation. Subsequently,the equations modeling the excess adsorption isotherm of high-pressure CH_4 adsorption on coal are obtained.Through the verification on the measurement data,the fitting results indicate that it is feasible to use the Ono-Kondo lattice mode to model the excess adsorption isotherm of high-pressure CH_4 adsorption on coal. 展开更多
关键词 COAL high-pressure methane excess adsorption isotherm Ono-Kondo lattice model
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Quality Control of 1-Alkyl-3-methylimidazolium Ionic Liquid Precursors with HPLC 被引量:2
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作者 张延强 张建敏 +1 位作者 陈玉涣 张锁江 《过程工程学报》 EI CAS CSCD 北大核心 2007年第6期1094-1098,共5页
A high performance liquid chromatography(HPLC) method was proposed to monitor the synthesis and purification of the 1-alkyl-3-methylimidazolium ionic liquid precursors from alkylation of 1-methylimidazole with alkyl h... A high performance liquid chromatography(HPLC) method was proposed to monitor the synthesis and purification of the 1-alkyl-3-methylimidazolium ionic liquid precursors from alkylation of 1-methylimidazole with alkyl halides and determine the purity of final products.The results showed that separation of 1-methylimidazole from the precursors could be obtained under the HPLC performance conditions such as cation exchange column,acetonitrile/KH2PO4 aqueous solution and 209 nm wavelength.The content of unreacted 1-methylimidazole in the precursors could be easily calculated from their corresponding HPLC peak areas with the calibration curve of 1-methylimidazole.The retention times of the 1-alkyl-3-methylimidazolium ionic liquid precursors decreased with their increasing alkyls,and the ionic liquids with the same cation and different anions had almost the same retention times. 展开更多
关键词 质量控制 1-烃基-3-甲基咪唑 液相色谱 离子性液体 前体 纯度 1-甲基咪唑
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Large scale synthesis of ZnO nanoparticles via homogeneous precipitation 被引量:3
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作者 王益明 李建华 洪若瑜 《Journal of Central South University》 SCIE EI CAS 2012年第4期863-868,共6页
In order to synthesize ZnO nanoparticles economically, industrial-grade zinc sulfate and urea were utilized to synthesize ZnO precursors in a stirred-tank reactor or a Teflon-lined autoclave at 100-180 ℃ under comple... In order to synthesize ZnO nanoparticles economically, industrial-grade zinc sulfate and urea were utilized to synthesize ZnO precursors in a stirred-tank reactor or a Teflon-lined autoclave at 100-180 ℃ under complete sealing condition. The ZnO precursors were calcined at 450 ℃ for 3 h to, synthesize ZnO nanoparticles. The composition of the precursors and the formation mechanism of ZnO were studied by thermogravimetric analysis and Fourier transform infrared spectroscopy. The results of X-ray diffraction, transmission electron microscopy and scanning electron microscopy of the ZnO powders demonstrate that high-purity zincite ZnO nanoparticles are synthesized. Orthogonal experiments were performed to find out the optimal conditions for the maximum yield and the minimum size. The ettect of temperature on the size ofZnO nanoparticles was investigated. The results show that a higher temperature is propitious to obtain smaller nanoparticles. 展开更多
关键词 ZNO homogeneous synthesis sealing condition thermogravimetric analysis
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A novel pathway for the preparation of Mg metal from magnesia 被引量:2
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作者 Zhimin Zhang Xuchen Lu Yan Yan 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2022年第10期2847-2856,共10页
High-purity anhydrous magnesium chloride was prepared from magnesia and ammonium chloride.The chlorination process was analyzed and then the critical stages affecting the purity of anhydrous magnesium chloride were pi... High-purity anhydrous magnesium chloride was prepared from magnesia and ammonium chloride.The chlorination process was analyzed and then the critical stages affecting the purity of anhydrous magnesium chloride were pinpointed.The effect of sample dimension on the above critical stages was investigated respectively.The purity guarantee mechanism of anhydrous magnesium chloride was proposed.After that,magnesium metal was obtained via electrolyzing the anhydrous magnesium chloride-containing molten salt.The new process for the continuous production of magnesium metal from magnesia was proposed and discussed.The incomplete chlorination reaction and the hydrolysis of anhydrous magnesium chloride are the two critical stages affecting the purity of the anhydrous magnesium chloride.The dimension of the sample can influence reaction process and reaction mechanism,and thus the problems of incomplete chlorination reaction and hydrolysis can be solved together.The magnesia content in anhydrous magnesium chloride was below 0.1 wt.%when the ratio of height to diameter of the sample was over 2.43.The content of impurities in the magnesium metal obtained met the specifications of the product Mg9980.The current efficiency was(94.7±1.8)%and the electricity consumption was(9107±97)kW h/t. 展开更多
关键词 MAGNESIUM ELECTROLYSIS Anhydrous magnesium chloride HYDROLYSIS
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Porous SiC Prepared Using Fine α-Al2O3 and SiC Powders as Sintering Additives 被引量:2
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作者 LIU Jiadong PENG Zhijian +2 位作者 LIU Qingzhu SUN Guangchao LIU Kaiqi 《China's Refractories》 CAS 2019年第2期31-36,共6页
A reaction bonding technique and a method of layer coating were developed to fabricate porous SiC.The green body was prepared using 250.0μm SiC particles as the raw material,fineα-Al2O3 and SiC powders with mass rat... A reaction bonding technique and a method of layer coating were developed to fabricate porous SiC.The green body was prepared using 250.0μm SiC particles as the raw material,fineα-Al2O3 and SiC powders with mass ratio of 2.5:1as sintering additives,65.2μm graphite as the pore-forming agent and polyvinyl alcohol(PVA)as the binder.The micro powders were coated on the surface of coarse SiC particles.After sintering,fine SiC particles were oxidized to silica(SiO2)then transforming into cristobalite,which finally reacted withα-Al2O3 to produce mullite(3Al2O3·2SiO2).The results show that SiC particles are bonded by the mullite and oxidation-derived SiO2.The apparent porosity of the specimens decreases from 31.3%to 20.5%with the amount of micro powders increasing from 5 mass%to 20 mass%.The bending strength increases at the first stage and then decreases with the increase of fine powders,and the specimen with 10 mass%of fine powders shows relatively high bending strength of 23.5 MPa. 展开更多
关键词 porous silicon CARBIDE POWDERS reaction BONDING POROSITY BENDING strength
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Determination of the intrinsic kinetics of iron oxide reduced by carbon monoxide in an isothermal differential micro-packed bed 被引量:1
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作者 侯宝林 张海英 +1 位作者 李洪钟 朱庆山 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第6期974-980,共7页
The intrinsic kinetics of iron oxide reduced by carbon monoxide is evaluated by a method of online measuring concentration of off-gas in an isothermal differential micro-packed bed. Under the condition of getting away... The intrinsic kinetics of iron oxide reduced by carbon monoxide is evaluated by a method of online measuring concentration of off-gas in an isothermal differential micro-packed bed. Under the condition of getting away from the influence of gas diffusion and gas–solid heat transfer and mass transfer, the reaction of Fe2O3 to Fe3O4, Fe3O4 to Fe O and Fe O to Fe in the process of single reaction can be clearly distinguished from each other, and the relevant activation energy is characterized to be 75.4, 74.4, and 84.0 k J·mol-1, respectively. Therefore, the change of surface area in the reaction process due to losing oxygen could be easily calculated by combining it with pre-exponential parameters of Arrhenius equations. In conclusion, these kinetic parameters are verified by the experimental data for the process of ore reduced by carbon monoxide in a packed bed. 展开更多
关键词 Activation energy Carbon Carbon monoxide Heat transfer Isotherms KINETICS Mass transfer Packed beds Surface reactions
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Suppressing secondary reactions of coal pyrolysis by reducing pressure and mounting internals in fixed-bed reactor 被引量:7
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作者 Shuai Cheng Dengguo Lai +5 位作者 Zhen Shi Leisheng Hong Jianling Zhang Xi Zeng Shiqiu Gao Guangwen Xu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第4期507-515,共9页
Pyrolysis of Shenmu coal was performed in fixed-bed reactors indirectly heated by reducing operating pressure and mounting internals in the reactor to explore their synergetic effects on coal pyrolysis. Mounting inter... Pyrolysis of Shenmu coal was performed in fixed-bed reactors indirectly heated by reducing operating pressure and mounting internals in the reactor to explore their synergetic effects on coal pyrolysis. Mounting internals particularly designed greatly improved the heat transfer inside coal bed and raised the yield of tar production.Reducing pressure further facilitated the production of tar through its suppression of secondary reactions occurring in the reactor. The absolute increase in tar yield reached 3.33 wt% in comparison with the pyrolysis in the reactor without internals under atmospheric pressure. The obtained tar yield in the reactor with internals under reduced pressure was even higher than the yield of Gray–King assay. Through experiments in a laboratory fixed bed reactor, it was also clarified that the effect of reducing pressure is related to volatile release rate in pyrolysis. It did not obviously vary tar yield at pyrolysis temperatures below 600 ℃, while the effect was evident at 650 and 700 ℃ but became limited again above 800 ℃. Under reduced pressure the produced tar contained more aliphatics and phenols but less aromatics. 展开更多
关键词 pyrolysis absolute volatile phenols suppression evident clarified contained heating bottle
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Synergetic NO reduction by biomass pyrolysis products simulating their reburning in circulating fluidized bed decoupling combustion 被引量:1
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作者 Hai-Sam Do Tuyet-Suong Tran +3 位作者 Zhennan Han Xi Zeng Shiqiu Gao Guangwen Xu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2019年第7期1680-1689,共10页
The present work investigated the synergetic effect of pyrolysis-derived char,tar and gas(py-gas)on NO reduction,which may occur in circulating fluidized-bed decoupling combustion(CFBDC)system treating N-rich fuel.Exp... The present work investigated the synergetic effect of pyrolysis-derived char,tar and gas(py-gas)on NO reduction,which may occur in circulating fluidized-bed decoupling combustion(CFBDC)system treating N-rich fuel.Experiments were carried out in a lab-scale drop-tube reactor for NO reduction by some binary mixtures of reagents including char/py-gas,tar/py-gas and tar/char.At a specified total mass rate of0.15 g·min^-1 for NO-reduction reagent,the char/py-gas(binary reagent)enabled the best synergetic NO reduction in comparison with the others.There existed effective interactions between char and some species in py-gas(i.e.,H2,CxHy)during NO reduction by pyrolysis products,meanwhile the tar/py-gas or tar/char mixture only caused a positive effect when tar proportion was necessarily lowered to about 26%.On the other hand,the synergetic effects were not improved for all tested binary reagents by increasing the reaction temperature and residence time. 展开更多
关键词 Biomass PYROLYSIS CIRCULATING fluidized BED NO reduction Synergetic effect DECOUPLING COMBUSTION
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Performance characteristics of fluidized bed syngas methanation over Ni-Mg/Al_2O_3 catalyst 被引量:1
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作者 刘姣 崔佃淼 +2 位作者 余剑 苏发兵 许光文 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第1期86-92,共7页
The performance characteristics of isothermal fluidized bed syngas methanation for substitute natural gas are investigated over a self-made Ni–Mg/Al2O3 catalyst. Via atmospheric methanation in a laboratory fluidized ... The performance characteristics of isothermal fluidized bed syngas methanation for substitute natural gas are investigated over a self-made Ni–Mg/Al2O3 catalyst. Via atmospheric methanation in a laboratory fluidized bed reactor it was clarified that the CO conversion varied in 5% when changing the space velocity in 40–120 L·g-1·h-1but the conversion increased obviously by raising the superficial gas velocity from 4 to12.4 cm·s-1. The temperature at 823 K is suitable for syngas methanation while obvious deposition of uneasyoxidizing Cγoccurs on the catalyst at temperatures around 873 K. From a kinetic aspect, the lowest reaction temperature is suggested to be 750 K when the space velocity is 60 L·g-1·h-1. Raising the H2/CO ratio of the syngas increased proportionally the CO conversion and CH4 selectivity, showing that at enough high H2/CO ratios the active sites on the catalyst are sufficient for CO adsorption and in turn the reaction with H2 for forming CH4.Introducing CO2 into the syngas feed suppresses the water gas shift and Boudouard reactions and thus increased H2 consumption. The ratio of CO2/CO in syngas should be better below 0.52 because varying the ratio from 0.52 to0.92 resulted in negligible increases in the H2 conversion and CH4 selectivity but decreased the CH4 yield.Introducing steam into the feed gas affected little the CO conversion but decreased the selectivity to CH4. The tested Ni–Mg/Al2O3 catalyst manifested good stability in structure and activity even in syngas containing water vapor. 展开更多
关键词 Syngas methanation Ni catalyst Fluidized bed Substitute natural gas Performance
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Chemical vapor deposition of SiC at different molar ratios of hydrogen to methyltrichlorosilane 被引量:1
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作者 杨艳 张伟刚 《Journal of Central South University》 SCIE EI CAS 2009年第5期730-737,共8页
Chemical vapor deposition(CVD) of SiC from methyltrichlorosilane(MTS) was studied at two different molar ratios of H2 to MTS(n(H2) /n(MTS) ) . The total pressure was kept as 100 kPa and the temperature was varied from... Chemical vapor deposition(CVD) of SiC from methyltrichlorosilane(MTS) was studied at two different molar ratios of H2 to MTS(n(H2) /n(MTS) ) . The total pressure was kept as 100 kPa and the temperature was varied from 850 to 1 100 ℃ at a total residence time of 1 s. Steady-state deposition rates as functions of reactor length and of temperature,investigated at different n(H2) /n(MTS) values,show that hydrogen exhibits strongly influences on the deposition rate. Especially,the deposition of Si co-deposit can be obtained in broader substrate length and at higher temperatures with increasing hydrogen partial pressure. Influence of hydrogen on the deposition process was also studied using gas phase composition and deposit composition analysis at various n(H2) /n(MTS) . SEM micrographs directly show the variation of surface morphologies at various n(H2) /n(MTS) . It can be found that the crystal grain of the deposit at 1 100 ℃ is better developed and the crystallization is also improved with increasing n(H2) /n(MTS) . 展开更多
关键词 METHYLTRICHLOROSILANE silicon carbide H2 MTS
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Preparation and Characterization of Low-melting Glasses Used as Binder for Protective Coating of Steel Slab 被引量:1
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作者 仉小猛 魏连启 +5 位作者 XU Haiwei WANG Shuhua YE Shufeng WANG Xiaojing ZHOU Xun CHEN Yunfa 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2013年第2期380-383,共4页
The low-melting phosphate glass was prepared for production of glass binders for protective coating of steel slab. Effects of different O/P ratios on glass structures and properties were analyzed. Differential thermal... The low-melting phosphate glass was prepared for production of glass binders for protective coating of steel slab. Effects of different O/P ratios on glass structures and properties were analyzed. Differential thermal analysis (DTA) and infrared spectroscopy (IR) techniques were applied for low-melting glass binder. It was found that the glass transition temperature(T) was about 300 ℃ and softening temperature(T1) was about 480 ℃. The choice of O/P ratio was very important to the glass transition and softening temperatures. When more P=O bonds existed in the glass networks, P-O-P bond angle was deformed with decreasing of the ratio of O/E The coatings could adhere to the substrates instantaneously at 800 ℃ when the content of binder exceeded 3wt%. The optimal content of glass binder was 5wt%. 展开更多
关键词 low-melting glasses binders steel slab protective coating
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Influence of Negative Pressure Gradient on Pressure Distribution and Gas-Solid Flow Pattern of Solid Feed Systems 被引量:1
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作者 Zhang Meiju Pan Feng +2 位作者 Shao Guoqiang Ge Yu Zhang Lei 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2018年第2期104-110,共7页
A series of experiments on a solid feed system was performed to investigate the effect of negative pressure gradient on the gas-solid flow pattern and hydrodynamic characteristics.Based on the non-fluidized gas-solid ... A series of experiments on a solid feed system was performed to investigate the effect of negative pressure gradient on the gas-solid flow pattern and hydrodynamic characteristics.Based on the non-fluidized gas-solid two phase flow and particulate mechanics in the standpipe,a method for predicting the pressure of the air passing through the recycle chamber and the pressure drop through the loop seal slit in these systems is also presented.The predicted pressure profile along the negative pressure gradient from the proposed model exhibits a good agreement with the experimental data.The experimental data show that the gas flow in the standpipe is always upward in the negative pressure gradients,while the direction ofthe superficial gas velocity through the recycle chamber of the loop seal does not affect the pressure drop in standpipe.It increases with an increasing negative pressure gradient. 展开更多
关键词 fuidized bed solid feedsystem negative pressure gradient gas-solid fow pattern
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CFD simulation of solids residence time distribution in a multi-compartment fluidized bed 被引量:1
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作者 Zheng Zou Yunlong Zhao +4 位作者 Hu Zhao Libo Zhang Zhaohui Xie Hongzhong Li Qingshan Zhu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第12期1706-1713,共8页
The present work focuses on a numerical investigation of the solids residence time distribution(RTD) and the fluidized structure of a multi-compartment fluidized bed, in which the flow pattern is proved to be close to... The present work focuses on a numerical investigation of the solids residence time distribution(RTD) and the fluidized structure of a multi-compartment fluidized bed, in which the flow pattern is proved to be close to plug flow by using computational fluid dynamics(CFD) simulations. With the fluidizing gas velocity or the bed outlet height rising, the solids flow out of bed more quickly with a wider spread of residence time and a larger RTD variance(σ2). It is just the heterogeneous fluidized structure that being more prominent with the bed height increasing induces the widely non-uniform RTD. The division of the individual internal circulation into double ones improves the flow pattern to be close to plug flow. 展开更多
关键词 RTD Bed geometry CFD Hydrodynamics Fluidization
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