检索结果-南通市图书馆

Journal of Central South University 2013年第12期20卷 3697-3714页

作者： J.O.Okeniyi I.O.Oladele I.J.Ambrose S.O.Okpala O.M.Omoniyi C.A.Loto A.P.I.Popoola Mechanical engineering department Covenant University chemical Metallurgical and Materials Engineering Department Tshwane University of Technology

Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in NaC1 and in H2SO4 media. For these, specifications of ASTM G16-95 R04 were combined with the normal and the Gumbel probability density functions as model analytical methods for addressing issues of conflicting reports of inhibitor effectiveness that had generated concerns. Results show that reinforced concrete samples admixed with concentrations having 4 g （0.012 7 tool）, 8 g （0.025 4 mol） and 6 g （0.019 l tool） NaaCr207 exhibited, in that order, high inhibition effectiveness, with respective efficiency, r/, of （90.46±1.30）%, （88.41＋2.24）% and （84.87±4.74）%, in the NaC1 medium. These exhibit good agreements within replicates and statistical methods for the samples. Also, optimal inhibition effectiveness model in the H2SO4 medium was exhibited by 8 g （0.025 4 mol） Na2Cr207 concentration having r/=（78.44±1.10）%. These bear implications for addressing conflicting test data in the study of effective inhibitors for mitigating steel-rebar corrosion in aggressive environments.

关键词： corrosion inhibitor effectiveness saline/marine and industrial/microbial environments concrete steel-rebar normal andGumbel probability distribution functions Kolmogorov-Smirnov statistics tests of significance

Kinetics of isothermal reduction of stainless steelmaking dust pellets

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2004年第3期14卷 593-598页

作者：彭及彭兵余笛唐谟堂宋海 J.Lobel3 J.A.Kozinski College of metallurgical Science and engineering College of Information Science and engineering department of metallurgical engineering

The stainless steelmaking dust pellets were reduced in isothermal temperature condition simulating the direct recycling practice in the stainless steel production and the kinetics of the reduction process was investigated. The pellets were formed after mixing the dust with carbon as the reducing agent and dolomite as the binder and smelting flux. An electric furnace was used to heat the pellets and an electrical microbalance was used to check the mass of the pellets in the reduction process. The reduction rate was calculated according to the data of pellet mass change in consideration of the evaporation of moisture, zinc and lead at high temperature. The results of the experiments show that the reduction process is in two consecutive stages. The reduction kinetic models were set up for each stage and the kinetic parameters such as activation energy and frequency factor were determined. The apparent activation energy of the first stage is 21.69 kJ/mol, and this stage is controlled by chemical reaction. The apparent activation energy of the second stage is 17.35 kJ/mol, and this stage is controlled by the diffusion of carbon monoxide through the resultants of reaction.

关键词：不锈钢炼钢尘泥等温分解动力学循环利用

Chitosan-praseodymium complex for adsorption of fluoride ions from water

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2015年第10期33卷 1104-1113页

作者： Eny Kusrini Nofrijon Sofyan Nyoman Suwartha Gefin Yesya Cindy Rianti Priadi department of chemical engineering Faculty of Engineering Universitas Indonesia department of metallurgical and Materials engineering Faculty of Engineering Universitas Indonesia department of Civil engineering Faculty of Engineering Universitas Indonesia

engineering of chitosan by praseodymium has been investigated to improve the adsorption properties as well as physical characteristics of chitosan. Modification of chitosan changes the original properties of chitosan so that it can be more suitable for adsorption of fluoride ions. In this study, chitosan-praseodymium （Chi-Pr） was synthesized by impregnation method. The Chi-Pr complex was characterized by scanning electron microscopic-energy dispersive X-ray spectroscopy （SEM-EDX）, Fourier transform infrared （FTIR） and employed as an adsorbent for removal of fluorides ions from water in the batch system. The variables such as contact time, concentration of Pr, adsorbent dose, initial concentration of fluoride ions, and competitor anions were studied. The adsorption efficiency of fluoride ions （n） with increasing Pr loading into chitosan （5 wt.%, 10 wt.%, 15 wt.%, 20 wt.% and 25 wt.%） were 35.5%, 56.1%, 72.0%, 68.5% and 62.5%, respectively. The Chi-Pr （15 wt.%） complex had the highest fluoride removal efficiency （72.0%）. The experimental data fitted well to the Langmuir isotherm with maximum adsorption capacity （qmax） of 15.87 mg/g and an equilibrium constant （kL） of 0.15 mg. Kinetic study revealed that the adsorption of fluoride ions from water followed pseudo-second-order model with a maximum adsorption capacity （q2） of 8.20 mg/g and a rate constant （k2） of 0.01 g/***. Adsorption efficiency of fluoride ions in the simulated drinking water was diminished with the changes in pH levels. The presence of Pr3＋ in chitosan increased chitosan＇s performance as an adsorbent for adsorption of fluoride ions.

关键词： adsorption of fluoride chitosan isotherms studies kinetics study praseodymium rare earths

Electrical conductivity optimization of the Na3AlF6–Al2O3–Sm2O3 molten salts system for Al–Sm intermediate binary alloy production

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2017年第9期24卷 1034-1042页

作者： Chun-fa Liao Yun-fen Jiao Xu Wang Bo-qing Cai Qiang-chao Sun Hao Tang Institute of metallurgical and chemical engineering Jiangxi University of Science and Technology

Metal Sm has been widely used in making Al–Sm magnet alloy materials. Conventional distillation technology to produce Sm has the disadvantages of low productivity, high costs, and pollution generation. The objective of this study was to develop a molten salt electrolyte system to produce Al–Sm alloy directly, with focus on the electrical conductivity and optimal operating conditions to minimize the energy consumption. The continuously varying cell constant(CVCC) technique was used to measure the conductivity for the Na3AlF6–AlF3–LiF–MgF2–Al2O3–Sm2O3electrolysis medium in the temperature range from 905 to 1055°C. The temperature(t) and the addition of Al2O3(W(Al2O3)), Sm2O3(W(Sm2O3)), and a combination of Al2O3and Sm2O3into the basic fluoride system were examined with respect to their effects on the conductivity(κ) and activation energy. The experimental results showed that the molten electrolyte conductivity increases with increasing temperature(t) and decreases with the addition of Al2O3or Sm2O3or both. We concluded that the optimal operation conditions for Al–Sm intermediate alloy production in the Na3AlF6–AlF3–LiF–MgF2–Al2O3–Sm2O3system are W(Al2O3) + W(Sm2O3) = 3wt%, W(Al2O3):W(Sm2O3) = 7:3, and a temperature of 965 to 995°C, which results in satisfactory conductivity, low fluoride evaporation losses, and low energy consumption.

关键词： aluminium oxide samarium oxide molten salt electrical conductivity regression analysis Al–Sm intermediate alloy

Spheroidizing Kinetics and Optimization of Heat Treatment Parameters in CK60 Steel Using Taguchi Robust Design

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2010年第4期17卷 45-52页

作者： Ata Kamyabi-Gol Meisam Sheikh-Amiri department of chemical and Materials engineering University of Alberta department of Materials Science and metallurgical engineering Ferdowsi University of Mashhad

For processing parts made from medium carbon steel, toughness and flexibility are of importance. There- fore, to achieve these properties, the cementite in the steels is spheroidized through heat treatment. Different parameters such as the time and temperature of spheroidizing and the initial microstructure of the steel affect the amount of spheroidized cementite. In the present work, the percent of contribution of two parameters, i.e. initial microstructure and spheroidizing time, to the percent of spheroidization in CK60 steel was investigated using Taguchi robust design. The initial microstructures consisted of martensite, coarse pearlite, fine pearlite and bainite and the chosen spheroidization times were 4, 8, 12, and 16h. Spheroidizing was done at the constant temperature 700℃. After spheroidizing was completed, the samples were prepared in order to observe their microstructure under an optical microscope and to determine the spheroidized percent using MIPTM （metallographic image processing） software. It was found that the spheroidizing time had the most influence （58.5 ~//0） on spheroidized percent and the initial microstructure only had a 31.1% contribution. Finally, the instantaneous growth rate of the carbide was also deduced.

关键词： spheroidizing kinetics heat treatment CK60 Taguchi

Volatilization of zinc and lead in direct recycling of stainless steel making dust

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2004年第2期14卷 392-396页

作者：彭及彭兵余笛唐谟堂 J.Lobel J.A.Kozinski School of metallurgical Science and engineering School of Information Science and engineering department of metallurgical engineering

The volatilization of zinc and lead from the stainless steel making dust pellets in the direct recycling procedure was conducted by using a thermo-gravimetric analyzer and a Tamman furnace in the nitrogen atmosphere respectively. The results show that the temperature has a significant effect on the volatilization rates of zinc and lead, and the carbon content in the pellets has no effect on the volatilization process. The volatilization of zinc is controlled by the chemical reaction between zinc oxide and carbon monoxide, while the volatilization of lead is controlled by the evaporation from liquid phase to the atmosphere. The volatilization of zinc and lead mainly happen at about 1 000 ℃ according to non-isothermal experiment.

关键词：不锈钢炼钢冶炼烟尘电弧炉 AOD炉 VOD炉

Influence of spark plasma sintering on microstructure and corrosion behaviour of Ti-6Al-4V alloy reinforced with micron-sized Si_3N_4powder

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2018年第5期14卷 403-407页

作者： F.M.Kgoete A.P.I.Popoola O.S.I.Fayomi department of chemical Metallurgical & Materials Engineering Tshwane University of Technology department of Mechanical engineering Covenant University

Ti-6 Al-4 V-Si3 N4 composites were effectively fabricated by spark plasma sintering(SPS) technique. The addition of Si_3 N_4 on Ti-6 AI-4 V was varied from 5% to 15%(wt fraction). The effect of Si_3 N_4 addition on the densification, microstructure, and microhardness and corrosion behaviour of Ti-6 Al-4 V was *** increase in microhardness value was recorded from 325.46 HV_(0.1) to 585.73 HV_(0.1). X-ray diffraction(XRD) analysis showed that the intensity of diffraction peaks of Si3 N4 phase in the composites *** sintered Ti-6 Al-4 V reinforced with Si_3 N_4 compacts revealed the non-existence of intermediate phases, such as TiSi_2(titanium silicide) which was expected. SEM analysis of the spark plasma sintered composites revealed a and β phase microstructures in Ti-6 Al-4 V with uniform distribution of Si3 N4 particulates in the matrix. The corrosion resistance property of the material was improved by the addition of Si_3 N_4 from 0.986629 mm/year to 0.030547 mm/year.

关键词： Spark plasma sintering Si3N4 Ti-6Al-4V Microstructure Corrosion

Direct microwave leaching conditions of rare earth elements in fluorescent wastes

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第6期42卷 1165-1174,I0007页

作者： A.Bilen B.Birol M.N.Saridede S.S.Kaplan M.S.Sonmez department of metallurgical and Materials engineering Yildiz Technical UniversityIstanbulTurkey department of chemical engineering and Materials Science Stevens Institute of TechnologyNew JereyUSA department of metallurgical and Materials engineering Istanbul Technical UniversityIstanbulTurkey

The luminescent phosphor powder in the fluorescent lamp constitutes 2%of the lamp’s *** can be mentioned that fluorescent wastes are a crucial raw material to produce rare earth *** the present study,microwave leaching process was conducted to dissolve rare earth elements yttrium(Y),europium(Eu),and remaining rare earth elements(REEs)present in the phosphor powder of the fluorescent *** the yields were *** the microwave leaching process,the effects of the temperature(80-160℃),acid type(hydrochloric acid(HCl),nitric acid(HNO_(3)),sulphuric acid(H_(2)SO_(4))),acid concentration(0.5-6 mol/L),solid to liquid ratio(0.1:10-0.5:10)and reaction time(5-90 min)parameters on leaching efficiencies of varying rare earth elements and calcium were *** highest yield was obtained in the direct microwave leaching of fluorescent waste with the experimental conditions of 6 mol/L HCl,160℃,0.1:10 solid-to-liquid ratio(S:L),and 90 *** energy calculations were made,and kinetic models of the reactions were obtained,and it is observed that Y and Eu dissolution is diffusion-controlled,on the other hand,lanthanum(La),cerium(Ce),and terbium(Tb)were examined to be chemical reaction ***,calcium(Ca)and gadolinium(Gd)seem coherent with the mixed ***,mathematical models of all experimental studies are created with the response surface Box-Behnken method and the correlation coefficients of all the models are over 90%.

关键词： Rare earth elements(REEs) Direct microwave leaching Fluorescent waste Kinetic models Response surface method

Electrochemical studies on interplay of mineralogical variation and particle size on bioleaching low grade complex sulphide ores

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2009年第5期19卷 1312-1325页

作者： P.A.OLUBAMBI J.H.POTGIETER S.NDLOVU J.O.BORODE department of chemical and metallurgical engineering Tshwane University of TechnologyPretoriaSouth Africa Chemistry and Materials Division School of BiologyChemistry and Health SciencesManchester Metropolitan UniversityUK School of chemical and metallurgical engineering University of the WitwatersrandJohannesburgSouth Africa department of metallurgical and Materials engineering Federal University of TechnologyAkureNigeria

The interplay of mineralogical variation and mineral phase distribution within varying particle sizes on the dissolution behaviour of a low grade complex sulphide ore was investigated through bioleaching experiments and electrochemical technique. Investigations were carried out utilizing mineralogical data on the variations in mineral and phase distribution within particle sizes of chemical investigations reveal the highest dissolution at particle size of 106μ*** results show that sphalerite rich phase has the highest dissolution rate while galena-rich complex phase has the *** studies confirm the highest bacterial attack at the sphalerite-rich *** discrepancies between the dissolutions within particle sizes obtained from bioleaching experiments and electrochemical studies are consistent with and attributed both to the physical and mineralogical *** behaviour is influenced and controlled by galvanic interaction resulting from mineralogical variation, while bioleaching behaviour is influenced by mineralogical variation as well as physical effect of particle size.

关键词：复杂硫化矿化学研究颗粒大小低品位浸出用电互作矿物

CORROSION AND MECHANICAL BEHAVIOR OF COPPER-NIOBIUM NANO-FILAMENTARY MICRO-COMPOSITES FOR HIGH PERFORMANCE ELECTRICAL CONDUCTOR WIRE

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2002年第2期15卷 154-159页

作者： Y Choi1), T.W.Lim1) and S.I. Hong2) 1)department of metallurgical engineering, Sunmoon University, Asan Chungnam 336-840, Korea 2)department of metallurgical engineering, Chungnam National University, Taedok Science Town, Daejeon 305-764,Korea department of metallurgical engineering Sunnioon University department of metallurgical engineering Chungnam National University

Corrosion behavior of heavily drawn bundled Copper-niobium filamentarymicro-composite was studied as a function of niobium content to develop the relationship betweenmicrostructure and corrosion behavior in aqueous 30 percent HCl-FeCl_3 solution. TEM observationrevealed that niobium filaments were distributed regularly in copper matrix along the sides of atriangular unit cell in the transverse section and more sub-grain boundaries were absorbed atcopper/niobium phase boundaries with increasing niobium content. The corrosion potential and rate inaqueous 30 percent HCl-10 percent FeCl_3 was-680.3m V_(SHE) and 1.179 X 10^(-5)A/cm^2. Thecorrosion potential and rate decreased as increasing niobium content and FeCl_3. The yield stresscan be described as the sum of the substructure strengthening component due to elongated grains,subgrains and/or cells, the phase boundary strengthening term associated with the Hall-Petch typeinteraction between dislocations and phase boundaries and precipitate strengthening component.

关键词： Cu-Nb micro-composites corrosion microstructure