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Effects of Ni doping on the structural properties and collapse of magnetic ordering in NdFe_(1-x)Ni_xO_3(0.1 ≤x≤ 0.7) orthoferrites

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Chinese Physics B 2016年第2期25卷 496-503页

作者： I.Ahmad M.J.Akhtar M.Siddique Department of metallurgy and Materials Engineering PIEAS Physics division PINSTECH

Nd Fe_（1-x）Ni_xO_3（0.1 ≤ x ≤ 0.7） orthoferrites are synthesized by solid state reaction method, and the structural properties of these materials are investigated by employing x-ray diffraction（XRD）, scanning electron microscopy（SEM） and M o¨ssbauer spectroscopy. The orthorhombic structure is observed in all systems; however, with the increase in Ni doping,the increase in tolerance factor and the decrease in the cell volume are observed. Orthorhombic distortion decreases with Ni content increasing up to 50%, while above 50% Ni doping it increases. SEM examination indicates the increases in grain size and intermixing of grains with increase in Ni concentration. Comparison between bulk and theoretical densities shows that in each of all samples porosity is less than 2%. M？ssbauer spectroscopic investigations are performed to explain local structure, Fe oxidation states and collapse of the magnetic ordering. In these samples the Fe oxidation state remains＋3 and there is no considerable increase in hole states observed; however due to mismatch of the ionic radii between Fe^（3＋） and Ni^（3＋）, octahedral distortions, sagging and distribution of hyperfine parameters increase with increase in Ni concentration. The major factors behind the collapse of magnetic ordering in the Ni-doped systems are the weakening of the super-exchange interactions, decrease in the Neel temperature, increase in spin–spin relaxation frequency and high spin to low spin transition.

关键词： ceramic crystal structure electron microscopy Mossbauer spectroscopy

Equilibrium and kinetic data of adsorption and separation for zirconium and hafnium onto MIBK extraction resin

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Transactions of Nonferrous Metals Society of China 2010年第8期20卷 1527-1533页

作者：徐志高吴延科张建东张力王力军 division of Mineral Resources Metallurgy and MaterialsGeneral Research Institute for Nonferrous Metals

The equilibrium and kinetics of methyl isobutyl ketone(MIBK) extraction resin for adsorption and separation of zirconium and hafnium were studied under the different conditions of acidity,initial total concentrations of zirconium and hafnium and *** equilibrium data of both zirconium and hafnium are found to follow the Freundlich adsorption isotherm,and the Freundlich isotherm constants(KF) are 3.53 and 0.64 mg/g,*** equilibrium data of zirconium also fit the Langmuir adsorption isotherm,and the saturation adsorption capacity(Qmax) and the Langmuir isotherm constant(KL)are 75.93 mg/g and-0.012 7 L/g,*** obtained kinetic data of both zirconium and hafnium are found to fit the HO pseudo-second-order kinetic model,and the rate constants of pseudo-second-order equation(k2) are-0.019 and 0.41 g/(mg·min),*** tests show that the MIBK extraction resin could be used as efficient adsorbent material for separating hafnium from zirconium.

关键词： equilibrium kinetics adsorption methyl isobutyl ketone extraction resin zirconium hafnium separation

Cobalt Recovery from Waste Catalysts (Petroleum Refining Industry from Gujarat)

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Open Journal of Metal 2012年第1期2卷 24-30页

作者： Palanivel Sivasakthi Natarajan Sathaiyan Department of electro-hydro metallurgy Central Electrochemical Research Institute Karaikudi India

A hydrometallurgical process has been developed for cobalt recovery from a waste catalyst (petroleum refining industry). This waste catalyst containing about 2.18 weight % of Co, is highly contaminated by Mg, Al, Si, Ca, Fe, Ni, Cu, Zn, Mo. The major steps are: (I) The spent catalyst is roasted with flux material in an electrical furnace at very high temperature (700?C) for a specific duration. (II) The roasted sample is leached with sulphuric acid to bring the metal contents into solution form. (III) For separating cobalt values from the leach solution, the solution pH is raised by NaOH addition, where all cobalt content is precipitated at a pH of about 12. (IV) This cobalt hydroxide precipitate is filtered and dissolved in minimum amount of sulphuric acid to get cobalt sulphate solution which is used as the electrolyte for the electrolytic recovery of cobalt. For optimizing various parameters like (1) H2SO4 concentration;(2) Duration;(3) Cobalt concentration;(4) Current density;(5) Temperature;(6) Stirring etc., The particle surface morphology and deposited layers have been characterized by scanning electron microscopy (SEM). A compact metallic deposit containing 70% cobalt was obtained.

关键词： hydrometallurgical electrowinning Cobalt Flux Material Waste Catalysts H2SO4 Leaching

Deposition rate of hafnium crystal bar by iodide process

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Rare Metals 2014年第2期33卷 161-165页

作者： Li-Sen Tian Yan-Xi Yin Zhi-Fang Hu Hong-Lin Jiang Zhong-Qi Li Li-Jun Wang division of Rare Metals Materials & metallurgy General Research Institute for Nonferrous Metals

Single variable and deposition weight methods were adopted in the experiment. The hafnium crystal bar was fabricated by the iodide process. Influence of hafnium filament temperature（K value）, temperature controlling method, types of feed, and the loading methods on the deposition rate were studied. The results show that the K value, temperature control method, types of feed, and the loading methods have obvious effects on the deposition rate of the hafnium crystal bar. The deposition rate increases with the K value rising in the range of certain temperature;the salt bath controlling temperature method could effectively obtain the better deposition rate; the greater the contact areas of the feeds are, the faster the deposition rate ***, the optimal iodide deposition techniques of preparing hafnium crystal bar are as follows： hafnium turnings as feed,molybdenum feed retainer charging, salt bath temperature controlling under the higher K value.

关键词： Iodide process Hafnium Deposition rate

Effect of processing routes on microstructure and mechanical properties of 2014 Al alloy processed by equal channel angular pressing

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Transactions of Nonferrous Metals Society of China 2010年第10期20卷 1822-1828页

作者： P.VENKATACHALAM S.RAMESH KUMAR B.RAVISANKAR V.THOMAS PAUL M.VIJAYALAKSHMI Department of Metallurgical and Materials Engineering National Institute of Technology Physical metallurgy division IGCAR

Al-Cu alloy was deformed through equal channel angular pressing(ECAP) by routes A,Ba,Bc and C up to 5 *** was done using a 90° die for three different conditions,namely 1) as received,2) solutionised at 768 K for 1 h and 3) solutionised at 768 K for 1 h + aged at 468 K for 5 *** microstructure,microhardness and tensile strength were studied for all the three conditions and four *** improvement in hardness(HV 184 after five passes) and strength(602 MPa after three passes) was observed in solutionised and aged 2014 Al alloy deformed through route *** evolution was reasonably equiaxed in route Bc with aspect ratio of *** and aged 2014 Al alloy deformed through route Bc was identified to have better microstructure and mechanical property than the other processing routes and conditions.

关键词： ECAP processing route 2014 aluminium alloy

Effect of Molybdate Ions on the Corrosion Behaviour of Ti Alloys

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Journal of Materials Science & Technology 2000年第1期16卷 45-49页

作者： Magda.M.A.Gad, Kamal.E.Mohamed and Abdelwahab A.El-Sayed (metallurgy Dept., Materials division, Atomic Energy Authority, Cairo, Egypt) metallurgy Dept. Materials Division Atomic Energy Authority Cairo Egypt

Titanium alloys are extensively used in power, chemical and petroleum industries as constructional materials for vessels and heat transfer tubes. Moreover they are candidate materials for nuclear waste disposal. These alloys have superior resistance to localized forms of corrosion compared to stainless steels and Ni-base alloys. However, this resistance is not as remarkable in crevice corrosion conditions in some aggressive media. electrochemical corrosion tests were conducted on two ASTM Ti grades namely, Ti-2 and Ti-12 in extremely low pH acidic environment. Results indicated that Ti-2 has less resistance to both general and crevice corrosion attack than Ti-12. Both alloys possess better resistance to general corrosion than to crevice corrosion. Also, results showed that the molybdate addition improves remarkably the resistance of Ti-2 to both types of attack. The increase of molybdate ions concentration from 0.03 mol/L to 0.15 mol/L made Ti-2 to be as resistant as, or somewhat higher than, Ti-12. The elecrochemical findings were further supplemented by optical examination of the corroded surface.

关键词： Ti Mo Effect of Molybdate Ions on the Corrosion Behaviour of Ti Alloys

hydrogen permeation resistance and characterization of Si–Al and Si–Zr composite sol oxide coating on surface of zirconium hydride

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Rare Metals 2017年第1期36卷 55-60页

作者： Ming Wu Yang Chen Jia-Qing Peng Guo-Qing Yan Yu-Pu Sun Jian-Dong Zhang Shun-Li Zhang Li-Jun Wang division of Rare Metals metallurgy and Materials General Research Institute for Nonferrous Metals Beijing 100088 China

The hydrogen permeation resistance of Si–Zr(SZ) and Si–Al(SA) composite sol oxide coating on zirconium hydride blocks(Zr H) was studied. SZ and SA composite sol were prepared by sol–gel method. SZ and SA composite oxide coatings were prepared on the surface of Zr H(in situ oxidized or not) in turns by dip-coating and heat treatment. hydrogen permeation of Zr Hwith and without composite oxide coating was *** desorption experiments in thermal vacuum show that hydrogen permeation resistance of SA composite oxide coating is better than that of SZ, to a certain extent,which could decrease hydrogen thermal loss. Experimental results in the working condition show that the SA composite oxide coating can not only prevent hydrogen permeation, but also retard contact and reaction between COand Zr Hmatrix, which could mitigate excessive oxidation of in situ oxide film. Differential scanning calorimetry and thermogravimetry(DSC–TG) analysis was performed to investigate the decomposition behavior of SA and SZ liquid sol in heat treatment process. X-ray diffraction(XRD) and scanning electron microscopy(SEM) analysis were employed to characterize the phase composition,surface and cross-section morphology of the coatings.

关键词： Zirconium hydride hydrogen permeation resistance Composite oxide coating Si–Zr Si–Al Sol–gel

electrochemical behavior of zirconium in molten NaCl-KCl-K_2ZrF_6 system

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Rare Metals 2011年第1期30卷 8-13页

作者： WU Yanke XU Zhigao CHEN Song WANG Lijun LI Guoxun division of Mineral Resources Metallurgy and MaterialsGeneral Research Institute for Nonferrous MetalsBeijing 100088China

The electrochemical reduction of Zr^4＋（complex） ions in NaCl-KCl-K2ZrF6 molten salt on Pt electrode was investigated using cyclic voltammetry and square wave voltammetry at 1023 *** cathodic reduction peaks related to Zr^4＋/Zr^2＋ and Zr^2＋/Zr steps were observed in the cyclic *** result was also confirmed by square wave *** diffusion coefficient of Zr^4＋（complex） ions at 1023 K in NaCl-KCl-K2ZrF6 melt,measured by cyclic voltammetry,is about 4.22×10^-6 cm^2/*** characterization of the deposits obtained by potentiostatic electrolysis at different potentials was investigated by XRD,and the results were well consistent with the electrochemical reduction mechanism of Zr^4＋（complex） ions.

关键词： molten materials salts zirconium electrochemical properties reduction cyclic voltammetry

Preparation of modified LiMn_(2)O_(4) by solid-state reaction

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Rare Metals 2006年第Z1期25卷 71-76页

作者： LU Shigang CAI Zhenping JIN Weihua LI Mingxun HUANG Songtao division of Mineral Resources Metallurgy&MaterialsGeneral Research Institute for Nonferrous MetalsBeijing 100088China

Modified lithium manganese oxides were prepared by solid-state reaction of LiMn_(2)O_(4)and LiCoO_(2)as raw materials.A study was carried out by TG-DSC,XRD,DSC and electrochemical to analyse the reaction process and structural characterization of *** results show that the LiMn_(2)O_(4)reacts chemically with LiCoO_(2)at high *** of Li and partial Co atoms can insert into the LiMn_(2)O_(4)crystal lattice and a newly formed spinel phase-modified LiMn_(2)O_(4)was *** distribution of Co content is even in modified LiMn_(2)O_(4)*** modified LiMn_(2)O_(4)compound exhibits improved cycling stability at room and elevated temperature in comparison with the pure LiMn_(2)O_(4).

关键词： lithium-ion battery spinel LiMn_(2)O_(4) modification process