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Cost-effective integrated strategy for the fabrication of hard-magnet barium hexaferrite powders from low-grade barite ore

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International Journal of Minerals,Metallurgy and Materials 2016年第9期23卷 991-1000页

作者： M.M.S.Sanad M.M.rashad central metallurgical r & d institute

Ultrafine barium hexaferrite（BaFe12O19） powders were synthesized from the metallurgical extracts of low-grade Egyptian barite ore via a co-precipitation route. Hydrometallurgical treatment of barite ore was systematically studied to achieve the maximum dissolution efficiency of Fe（～99.7%） under the optimum conditions. The hexaferrite precursors were obtained by the co-precipitation of BaS produced by the reduction of barite ore with carbon at 1273 K and then dissolved in diluted HCl and FeCl3 solution at pH 10 using NaOH as a base; the product was then annealed at 1273 K in an open atmosphere. The effect of Fe^3＋/Ba^2＋ molar ratio and the addition of hydrogen peroxide（H2O2） on the phase structure, crystallite size, morphology, and magnetic properties were investigated by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. Single-phase BaFe（12）O（19） powder was obtained at an Fe^3＋/Ba^2＋ molar ratio of 8.00. The formed powders exhibited a hexagonal platelet-like structure. Good maximum magnetization（48.3 A×m^2×kg^–1） was achieved in the material prepared at an Fe^3＋/Ba^2＋ molar ratio of 8.0 in the presence of 5% H2O2 as an oxidizer and at 1273 K because of the formation of a uniform, hexagonal-shaped structure.

关键词： chemical process barite ore treatment characterization magnetic properties ferrites

Investigation of improving wear performance of hypereutectic 15%Cr-2%Mo white irons

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China Foundry 2010年第4期7卷 438-446页

作者： r.reda A.Nofal Kh.Ibrahim A.Hussien central metallurgical r&d institute Faculty of Engineering Cairo University

This study aimed at optimizing impact toughness and abrasion wear resistance of 15%Cr-2%Mo hypereutectic abrasion-resistant white irons. The effects of dynamic solidification, niobium addition, combined action of them and heat treatment have been investigated. Investigations were performed by means of the image analyzer, scanning electron microscopy (SEM), energy-dispersive spectrometry (EdS) and X-ray diffraction. Impact toughness and abrasion wear resistance tests were conducted. Fracture and worn surfaces were studied. results indicated that microstructural control during solidifciation is the most valuable tool to attain the optimum combination between impact toughness and wear resistance in hypereutectic iron. Combined action of Nb addition and dynamic solidifciation improves impact toughness and wear resistance even more than the action of each individual factor. In the as-cast condition, impact toughness and abrasion resistance were increased after dynamic solidification compared to statically solidified one by 71.4% and 10%, respectively. This enhancement was increased to 114.3 % and 28.8 % by adding 2% Nb. Lower tempering temperature of 260°C exhibits better impact and abrasion resistance than the sub-critical tempering temperature of 500°C.

关键词： hypereutectic Cr-Mo white iron dynamic solidifciation Nb combined action heat treatment impact toughness fractography wear resistance worn surface

Mechanical characterization of cp-Ti produced by investment casting

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Transactions of Nonferrous Metals Society of China 2011年第8期21卷 1735-1740页

作者： Khaled M.IBrAHIM Mansour MHAEdE Lothar WAGNEr central metallurgical r&d institute(cmrdi) Institue of Materials Science and Engineering TU-Clausthal

The influence of hot swaging（SW） and annealing treatment on microstructure and mechanical properties of commercially pure titanium produced by investment casting was *** as-cast samples showed a typical microstructure consisting of a variety of α-morphologies,while the hot swaged samples exhibited a kinked lamellar *** at 500 °C did not significantly change this microstructure while annealing at 700 and 870 °C led to recrystallization and formation of equiaxed *** cast bars exhibited a typical hard α-layer in near-surface regions with a maximum depth and maximum hardness of 720 μm and HV0.5 660,*** to SW,the tensile strength of the as-cast material drastically increased from 605 MPa to 895 *** at 500 °C decreased the tensile strength slightly from 895 to 865 MPa while annealing at 700 °C led to a further pronounced drop in tensile strength from 865 to 710 *** additional decrease in tensile strength was noticed with increasing the annealing temperature from 700 to 870 °*** true fracture strain of the as-cast and hot swaged samples was in the range of 0.05 to 0.12,while the annealed samples showed values in the range of 0.25 to *** addition,the as-cast and hot swaged samples revealed a brittle cleavage fracture ***,the annealed samples showed a transgranular ductile fracture with formation of dimples.

关键词： pure titanium investment casting swaging thermo-mechanical processing mechanical properties

Effect of Si-addition as a grain refiner on microstructure and properties of Ti-6Al-4V Alloy

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Transactions of Nonferrous Metals Society of China 2013年第7期23卷 1863-1874页

作者： Khaled M.IBrAHIM Abdel Hamied HUSSEIN Mohamed ABdELKAWY central metallurgical r&d institute CMRDICairoEgypt Cairo University GizaEgypt

Two different Ti alloys were cast in a graphite mould using vacuum induction skull melting furnace. The first alloy was Ti-6Al-4V and the second was Ti-6Al-4V 0.5Si. Silicon as a grain refiner was added into Ti-6Al-4V alloy, and the effects of Si-addition on the microstructure and properties of the as-cast and swaged alloys were investigated. Hot swaging at 900 °C was performed on the cast samples and then two different thermal treatments were applied. The first treatment was done by heating the swaged samples at 1050 °C to produce fine lamella structure, while the second treatment was carried out at 1050 °C and then decreased the temperature to 800 °C for getting coarse lamella structure. An addition of 0.5% Si to Ti-6Al-4V alloy decreased the grain size of the as-cast sample from 627 to 337 μm. There was an increase in ultimate tensile strength of about 25 MPa for the as-cast Ti-6Al-4V 0.5Si alloy compared to Ti-6Al-4V due to the refinement effect caused by Si addition. A maximum ultimate tensile strength of 1380 MPa and a minimum corrosion rate （1.35×10 6 mm/a in Hank’s solution and 5.78×10 4 mm/a in NaCl solution） were reported for the heat treated fine lamella structure of Ti-6Al-4V 0.5Si alloy. The wear rate was decreased to about 50% by adding 0.5% Si at low sliding speeds and to about 73% at high sliding speeds.

关键词： Ti-6Al-4V alloy silicon casting grain refinement heat treatment wear

rare Earth Elements in Egyptian Phosphorites

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Chinese Journal Of Geochemistry 2002年第1期21卷 19-28页

作者： I.S. ISMAEL(central metallurgical r & d institute, P.O. Box 87 Helwan, Cairo, Egypt) central metallurgical r & d institute Cairo Egypt

Egyptian phosphorites from Abu Tartur (Western desert), El Mahamide mine (Nile Valley) and rabah mine (Eastern desert) show variable degrees of relative rEE enrichment. Black plateau phosphorites of Abu Tartur are substantially enriched in rEE as compared to the red Sea and Nile Valley phosphorites. P-rich organic matter from the Abu Tartur and rabah mines recorded negative Ce and positive Eu anomalies. Positive Eu anomaly reveals an anoxic event prior to the phase of Late Cretaceous phosphate formation. Ce is a redox indicator. Mixing of sea water and upwelling during the Late Cretaceous was responsible for the recording of positive Eu and negative Ce anomalies in the Egyptian phosphorites.

关键词：稀土元素磷灰石埃及 rEE

The Mechanism of Heating rate on the Secondary recrystallization Evolution in Grain Oriented Silicon Steel

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Journal of Wuhan University of Technology(Materials Science) 2025年第1期 275-282页

作者：高倩 LI Jun WANG Xianhui CAO Laifu GONG Jian LI Bo central Iron and Steel research institute Group Shougang Zhixin Electromagnetic Material r&d (Beijing) Co. Ltd. Beijing Shougang Co. Ltd.

Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing, in which the evolution of magnetic properties, grain orientations and precipitates were studied. To illustrate the Zener factor, the diameter and number density of precipitates of interrupted testing samples were statistically calculated. The effect of precipitate ripening on the Goss texture and magnetic property was investigated. data indicated that the trend of Zener factor was similar under different heating rates, first increasing and then decreasing, and that the precipitate maturing was greatly inhibited as the heating rate increased. Secondary recrystallization was developed at the temperature of 1 010 ℃ when a heating rate of 5 ℃/h was used, resulting in Goss, Brass and {110} oriented grains growing abnormally and a magnetic induction intensity of 1.90T. Furthermore, increasing the heating rate to 20 ℃/h would inhibit the development of undesirable oriented grains and obtain a sharp Goss texture. However, when the heating rate was extremely fast, such as 40 ℃/h, poor secondary recrystallization was developed with many island grains, corresponding to a decrease in magnetic induction intensity to 1.87 T. At a suitable heating rate of 20 ℃/h, the sharpest Goss texture and the highest magnetic induction of 1.94 T with an onset secondary recrystallization temperature of 1 020 ℃ were found among the experimental variables in this study. The heating rate affected the initial temperature of secondary recrystallization by controlling the maturation of precipitates, leading to the deviation and dispersion of Goss texture, thereby reducing the magnetic properties.

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debinding of stainless steel foam precursor with 3-d open-cell network structure

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Transactions of Nonferrous Metals Society of China 2010年第12期20卷 2340-2344页

作者：李昌林王辉周向阳李劼刘宏专 School of metallurgical Science and Engineering Central South University

The thermal debinding behavior of stainless steel foam precursor in vacuum was studied and compared with that in *** formation cause of pore channel was *** experiment results show that the binder removal rate in vacuum is higher than that in *** vacuum,the organic compounds can be removed effectively without change of pore size and the pore morphology for the *** pre-sintering,some sintering necks form and the sample has certain *** initial surface pore forms with the temperature increasing at first,and then the internal melting binder is aspirated to form initial pore because of the capillary force and the metal powders re-arrange with the migration of binder at the same time.

关键词： precursor stainless steel foam vacuum thermal debinding pore channel

Experimental Study for Effect of Multi-Site Spark Ignition on dedicated Hybrid Engine Performance under High dilution Condition

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Journal of Thermal Science 2025年第1期 254-267页

作者： YAN Bowen WATErS Benjamin HAINES Andrew MCGHEE Mike HU Tiegang dENG Wei PU Yongxian MA Tianyu Powertrain Engineering r&d Center Chongqing Changan Automobile Co.Ltd. Changan UK r&d Centre Limited

In this study,a triple spark ignition scheme was first designed on a three-cylinder 1.5-L dedicated hybrid engine（dHE）.On this basis,the effect of different ignition modes on engine combustion and emission characteristics was studied,especially under high dilution *** results tested at 2000 r/min and 0.8 MPa BMEP（brake mean effective pressure） show that with highly increased in-cylinder flow intensity,using only passive prechamber（PPC） has a lower lean limit than that with single central spark plug（CSP）,thereby leading to slightly higher minimum fuel consumption and nitrogen oxides（NOx） *** side spark plugs（SSP）based on PPC can result in improved capability of lean limit extension and engine performance than ***,the improvement level is lower than that with triple spark plugs（TSP）.As the excess air ratio λincreases,the advantage of PPC and PPC with SSP in improving the combustion phasing compared with CSP gradually ***,the increasing tendency of their ignition delay and combustion duration is more *** added SSP based on PPC can effectively shorten the ignition delay of leaner mixture,but the combustion duration can be only slightly *** a result,under extremely lean condition,the advantage of PPC and PPC with SSP in terms of combustion characteristics over CSP becomes much *** contrast,the TSP ignition can achieve much shorter ignition delay and combustion duration simultaneously under this *** to the highest available dilution level,the TSP ignition achieves the lowest raw ***,it can also reduce the raw carbon monoxide（CO） and hydrocarbons（HC） emissions compared to CSP due to a more thorough combustion of the end gas *** on the excellent performance of TSP,the highest engine brake thermal efficiency（BTE） was further *** results show that with normal rON 92 fuel,the engine finally achieved 43.69% and 45.02% BTE under stochiometric mode with exhaust

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Anisotropic alignments of hierarchical Li2SiO3/TiO2@nano-C anode//LiMnPO4@nano-C cathode architectures for full-cell lithium-ion battery

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National Science review 2020年第5期7卷 863-880页

作者： Hesham Khalifa Sherif A. El-Safty Abdullah reda Mohamed A. Shenashen Alaa I.Eid research Center for Functional Materials National Institute for Materials Science department of Petrochemical Egyptian Petroleum Research Institute Composite Lab Advanced Materials Division Central Metallurgical R&D Institute

We report on low-cost fabrication and high-energy density of full-cell lithium-ion battery (LIB) ***-hierarchical electrode architectures of Li2SiO3/TiO2@nano-carbon anode (***@nano-C) and high-voltage olivine LiMnPO4@nano-carbon cathode (LMPO@nano-C) are designed for half-and full-system LIB-Cr2032 coin cell *** the basis of primary architecture-power-driven LIB geometrics,the structure keys including three-dimensional (3d) modeling superhierarchy,multiscale micro/nano architectures and anisotropic surface heterogeneity affect the buildup design of anode/cathode LIB *** hierarchical electrode surface topologies enable continuous in-/out-flow rates and fast transport pathways of Li+-ions during charge/discharge *** stacked layer configurations of pouch LIB-types lead to excellent charge/discharge rate,and energy density of237.6 Wh *** the most promising LIB-configurations,the high specific energy density of hierarchical pouch battery systems may improve energy storage for long-driving range of electric ***,the anisotropic alignments of hierarchical electrode architectures in the large-scale LIBs provide proof of excellent capacity storage and outstanding durability and *** full-system LIB-Cr2032 coin cell models maintain high specific capacity of～89.8%within a long-term life period of2000 cycles,and average Coulombic efficiency of99.8%at 1C rate for future configuration of LIB manufacturing and commercialization challenges.

关键词： lithium-ion batteries micro/nano architectures LiMnPO4@nano-carbon cathode Li2SiO3/TiO2@nano-carbon anode LIB-Cr2032 coin cell models