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Plasma Science and Technology 2013年第6期15卷 562-569页

作者： B.DEBALINA M.KAMARAJ S.R.CHAKRAVARTHI N.J.VASA R.SARATHI dept.of metallurgical and materials engg. IIT MadrasChennai 600036India dept.of Aerospace engg. IIT MadrasChennai 600036India dept.of Engineering Design IIT MadrasChennai 600036India dept.of Electrical engg. IIT MadrasChennai 600036India

In the present study nano-tungsten carbide particles were generated in a wire explosion *** plasma generated during the wire explosion process was analyzed using optical emission spectroscopy（OES）.The impact of ambient pressure on the plasma temperature,electron density and plasma lifetime was *** variations of the plasma produced under different experimental conditions were *** produced nanoparticles were characterized through wide angle X-ray diffraction（WAXD） and transmission electron microscopy（TEM） studies. Particles produced with a negative DC charging voltage had a larger mean size when compared to a positive charging *** dependence on the plasma duration was observed where plasma was sustained for a longer duration with a negative DC charging voltage.

关键词： optical emission wire explosion tungsten carbide life time nano particle

Interfacial Microstructure of Diffusion Bonded Inconel 738 and Ferritic Stainless Steel Couple

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Journal of materials Science & Technology 2009年第4期25卷 527-530页

作者： Bulent Kurt Mustafa Ulutan Bartin University Faculty of EngineeringDept.of Metallurgical and Materials Engineering University of Eskisehir Osmangazi Faculty of EngineeringDept. of Mech.Eng

In this study, Inconel 738 alloy was diffusion bonded to a ferritic stainless steel. The effect of bonding temperature on the microstructural development across the joint region was investigated. Following the diffusion bonding, conventional characterization techniques such as scanning electron microscopy （SEM）, energy dispersive X-ray （EDX） and microhardness were used to examine the interracial microstructure. It was seen that bonding temperature was effective on the diffusion of Ni from Inconel 738 to ferritic stainless steel that affected the microstructure of the interface. Austenite phase was formed at the interface as a result of Ni diffusion from the Inconel 738 to the interface.

关键词： Diffusion bonding Inconel 738 Ferritic stainless steel Interface

Enhancement and Optimization of ATO Nano-crystalline Films Properties by the Addition of Acetylacetone as Modifier in the Sol-gel Process

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Journal of Wuhan University of Technology(materials Science) 2015年第5期30卷 873-881页

作者： Galaviz-pérez J A CHEN Fei SHEN Qiang Vargas-garcía J R 张联盟 State Key Laboratory of Advanced Technology for materials Synthesis and Processing Wuhan University of Technology dept.of materials and metallurgical Eng. National Polytechnic Institute

Sb-doped Sn O2(ATO) thin films have been prepared using the spin coating method by selecting the proper amount of acetylacetone as solution modifier. All ATO powders and films exhibited the cassiterite rutile-like structure in a crystal size below 10 nm under all the experimental conditions and a nonpreviously reported crystal structure was observed at high acetylacetone loads. The acetylacetone molar ratio influenced notably the optical and electrical properties of ATO films. When prepared at an acetylacetone molar ratio of 4, ATO films exhibited optical transparencies above 90% in the visible region and above 40% in the UV region for thicknesses of 100 and 300 nm. Films in a thickness of 100 nm and at an annealing temperature of 650 ℃ accounted for a high transparency of 97% in the visible wavelength. Films prepared at an acetylacetone molar ratio of 4 exhibited an electric resistivity of 1.33×10-3 Ω·cm at an annealing temperature of 650 ℃. The optimal Sb content for ATO films was found to be 8 at%. The relationships among the properties of starting solutions, the experimental parameters, and properties of ATO films are discussed.

关键词： tin oxide films antimony doping acetylacetone optical transparency electric properties

Exploring relationships of gross calorific value and valuable elements with conventional coal properties for North Korean coals

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International Journal of Mining Science and Technology 2019年第6期29卷 867-871页

作者： Saeed Chehreh Chelgani Minerals and metallurgical Engineering Dept.of Civil Environmental and Natural Resources Engineering Lule? University of Technology

Coal in North Korean(NKC)is one of the most important products;however,based on various strategic policies its detail properties remain opaque even for general *** there are some signs for opening of the North Korea economy,this investigation as a modest effort is going to explore principle relationships among some essential parameters of NKCs such as gross calorific value(GCV),valuable elements and conventional properties by different statistical *** indicated that ultimate parameters(carbon,nitrogen,and hydrogen)are the best GCV predictors for NKCs in comparison with proximate parameters(ash,moisture and volatile matter).Multivariable regression demonstrated that predicted GCV based on ultimate properties has a quite accuracy when correlation of determination was *** statistics processes showed that on average,the contents of valuable elements such as Ga and V for NKCs are higher than the world coal ranges and they can be considered as byproducts of combustion of *** correlations indicated that Y may have a mixed organic-inorganic affinity while Ga and V mainly occur in the inorganic part(mineral matter)of *** inter-correlations between Ga-V and Al showed that aluminosilicates can be considered as their main bring minerals.

关键词： Yttrium Gallium Vanadium Calorific value Energy By product

Microstructure and Properties of Superplastic Welding between 40Cr and CrWMn Steels

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Journal of materials Science & Technology 2001年第1期17卷 175-176页

作者： Jiuba WEN Yongshun YANG dept.of materials Engineering Luoyang institute of TechnologyLuoyang 471039China

Superplastic welding of tool steel and structural steel was investigated. The welding between 40Cr and CrWMn steels was carried out under the conditions of temperature 750~780℃, strain rate 2×10-4s-l, compressive stress 50-90 MPa for 3-5 min. The joints show similar strength to that of 40Cr steel and the good metallurgical joining is formed. The structural change occurring during Superpfastic welding was analyzed by metallography and distribution of carbon content in the vicinity of the welding joint was also determined. The mechanism of superplastic welding for steels is proposed to be the disappearance of original bond interfaces caused by atomic diffusion and the grain sliding.

关键词： structural change structural steel atomic diffusion carbon content welding joint tool steel

Numerical simulation and experimental validation of arc welding of DMR-249A steel

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Defence Technology（防务技术） 2016年第4期12卷 305-315页

作者： Rishi PAMNANI M. VASUDEVAN T. JAYAKUMAR R VASANTHARAJA K.C. GANESH Prototype Training Centre Kalpakkam Tamil Nadu 603 127 India IGCAR Tamil Nadu 603 102 India metallurgical and materials engg.dept NIT Warangal 506 004 India dept.of Mech engg NITT Tiruchirappalli 620 015 India

The thermo-mechanical attributes of DMR-249 A steel weld joints manufactured by shielded metal arc welding(SMAW) and activated gas tungsten arc welding(A-GTAW) processes were studied using Finite Element Model(FEM) simulation. The thermal gradients and residual stresses were analyzed with SYSWELD software using double ellipsoidal heat source distribution model. The numerically estimated temperature distribution was validated with online temperature measurements using thermocouples. The predicted residual stresses profile across the weld joints was compared with the values experimentally measured using non-destructive techniques. The measured and predicted thermal cycles and residual stress profile was observed to be comparable. The residual stress developed in double sided A-GTAW joint were marginally higher in comparison to five pass SMAW joint due to phase transformation associated with high heat input per weld pass for A-GTAW process. The present investigations suggest the applicability of numerical modeling as an effective approach for predicting the thermo-mechanical properties influenced by welding techniques for DMR-249 A steel weld joints. The tensile, impact and micro-hardness tests were carried to compare the *** benefits of high productivity and savings of labor and cost associated with A-GTAW compared to SMAW process, the minor variation in residual stress build up of A-GTAW joint can be neglected to develop A-GTAW as qualified alternative welding technique for DMR-249 A steel.? 2016 China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.

关键词： DMR-249A A-GTAW SMAW FEM SYSWELD Thermo-mechanical Simulation

Beneficiation Study on a Nigerian Baryte Ore for Industrial Use

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Journal of materials Science & Technology 1997年第1期13卷 76-78页

作者： V. O.Nwoko and O. O. Onyemaobi (dept. of materials and metallurgical Engineering, Federal University of Technology, Owerri, Nigeria) dept. of materials and metallurgical Engineering Federal University of Technology Owerri Nigeria

Beneficiation study on samples of baryte ore from Azare in the Plateau State of Nigeria was carried out using chemical analysis, atomic absorption spectrophotometric analysis, jigging and magnetic separation. Results show that Azare baryte can profitably be concentrated for use in oil drilling and other industrial purposes. Barium sulphate content in the head ore analyzed, is 98%. Comparison between jigging and magnetic separation shows that jigging produces a more satisfactory result.

关键词： Beneficiation Study on a Nigerian Baryte Ore for Industrial Use

Evaluating location specific strain rates, temperatures,and accumulated strains in friction welds through microstructure modeling

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Defence Technology（防务技术） 2018年第2期14卷 83-92页

作者： Javed Akram Prasad Rao Kalvala Vikas Jindal Mano Misra dept. of metallurgical Engineering University of Utah dept. of metallurgical Engineering Indian Institute of Technology(BHU)

A microstructural simulation method is adopted to predict the location specific strain rates, temperatures, grain evolution, and accumulated strains in the Inconel 718 friction welds. Cellular automata based 2D microstructure model was developed for Inconel 718 alloy using theoretical aspects of dynamic recrystallization. Flow curves were simulated and compared with experimental results using hot deformation parameter obtained from literature work. Using validated model, simulations were performed for friction welds of Inconel 718 alloy generated at three rotational speed i.e., 1200, 1500, and1500 RPM. Results showed the increase in strain rates with increasing rotational speed. These simulated strain rates were found to match with the analytical results. Temperature difference of 150 K was noticed from center to edge of the weld. At all the rotational speeds, the temperature was identical implying steady state temperature(0.89 T_m) attainment.

关键词： Microstructure modeling Dynamic recrystallization Friction welding Inconel 718 EBSD Hot deformation Strain map

Microstructure and Mechanical Properties of Friction Stir Lap Welded Aluminum Alloy AA2014

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Journal of materials Science & Technology 2012年第5期28卷 414-426页

作者： S. Babu G.D. Janaki Ram P.V. Venkitakrishnan G. Madhusudhan Reddy K. Prasad Rao dept. of metallurgical and materials Engineering Indian Institute of Technology Madras Chennai India Liquid Propulsion Systems Centre Indian Space Research Organisation Tiruvananthapuram India Defence metallurgical Research Laboratory Hyderabad India

Friction stir lap welds were produced in 3 mm thick Alclad sheets of Al alloy 2014-T4 using two different tools （with triangular and threaded taper cylindrical pins）. The effects of tool geometry on weld microstructure, lap-shear performance and failure mode were investigated. The pin profile was found to significantly influence the hook geometry, which in turn strongly influenced the joint strength and the failure mode. Welds produced in alloy 2014-T4 Alclad sheets by using triangular and threaded taper cylindrical tools exhibited an average lap-shear failure load of 16.5 and 19.5 kN, respectively, while the average failure load for standard riveted joints was only 3.4 kN. Welds produced in alloy 2014-T6 Alclad sheets and in alloy 2014-T4 bare sheets （i.e., no Alclad） were comparatively evaluated with those produced in alloy 2014-T4 Alclad sheets. While the welds made （with threaded taper cylindrical tool） in T6 and T4 conditions showed very similar lap-shear failure loads, the joint efficiency of the welds made in T6 condition （43%） was considerably lower （because of the higher base material strength） than those made in T4 condition （51%）. The Alclad layers were found to present no special problems in friction stir lap welding. Welds made with triangular tool in alloy 2014-T4 Alclad and bare sheets showed very similar lap-shear failure loads. The present work provides some useful insights into the use of friction stir welding for joining Al alloys in lap configuration.

关键词： Aluminum alloys Friction stir welding Lap joints Lap-shear testing

Modeling of Reversibleγ/αTransformations of Low Carbon Steels in the Intercritical Temperature Range

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材料热处理学报 2004年第5B期25卷 702-705页

作者： Tamás RTl Imre FELDE Hakan GR Budapest Polytechnic Budapest HungaryBay Zoltdn Institute for Materials Science and Technology Budapest HungaryMetallurgical and Materials Eng. Dept. Middle East Technical University Ankara Turkey

A phenomenological kinetic model has been developed for the prediction of non-isothermal reversible incomplete transformations in low-carbon hypoeutectoid steels. The theoretical basis of the proposed method has its origin in a possible extension of the traditional Austin-Rickett kinetic differential equation. To critically assess the applicability of the model, a number of experiments based on computer simulations have been performed to predict the austenite/ferrite proeutectoid transformation in the temperature range of Aei to Ae3 on plain carbon hypoeutectoid steels. A comparison with published experimental data has verified that the model developed is reasonable both quantitatively and with respect to well-established trends. Extension of the method of prediction appears promising when the non-isothermal reactions occurring during heat treatment (such as carbide precipitation and dissolution) can be assumed to proceed in a reversible manner.

关键词：奥氏体转变动力学低碳钢临界温度