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The Latest Research Development on Modification of High Voltage Cathode Material LiNi0.5Mn1.5O_4

Rare Metals and Cemented Carbides | Vol., Issue 2, 2016 | pp. 68-75
The latest research is reviewed on the synthesis and modification of 5V spinel LiNi_(0.5)Mn_(1.5)O_4 cathode material at home and abroad in respect of crystal structure,preparation method,phase doping modification and surface coating modification.And its future development is also proposed.
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Experimental Study on Cutting Stainless Steel with Different Grain Size Cemented Carbide Tools

Rare Metals and Cemented Carbides | Vol., Issue 2, 2016 | pp. 76-80
The mechanical and physical properties were tested of WC-Co-based cemented carbide with medium,fine and ultra-fine grain size,and the surface morphology of cemented carbide was observed by SEM before and after corrosion.The above three kinds of cemented carbide blades were employed in dry cutting of 0Cr18Ni9 stainless steel.Average wear width on the flank face of cutting blades was measured at different cutting rate,the wear morphology was observed by SEM,and tool wear mechanism was analyzed.The results show that the finer the WC grains,the better the wear resistance and the longer the working life of cemented carbide tools.Adhesive wear is found to be the main wear mechanism of cemented carbide tools during continuous cutting of stainless steel.
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Research and the Latest Development of Gallium Recovery Process and Technology

Rare Metals and Cemented Carbides | Vol., Issue 1, 2016 | pp. 1-8
The technology and process for gallium industrial production and gallium extraction from coal ash are summarized.In view of the advantages and disadvantages of each gallium recovery process,the current research on the application of resin method in acid system is emphatically analyzed.The proposals are put forward for development of gallium recovery technology in hydrochloric acid system.
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Thermodynamic Analysis of Ti and Metal Impurities of Cr and Ni during High-purity Titanium Production with Iodination Method

Rare Metals and Cemented Carbides | Vol., Issue 1, 2016 | pp. 9-14
Titanium with the purity higher than 4N5 was prepared with iodination method and electron-beam smelting method.During iodination,TiI4 was produced in 800-900Khalogenation area from crude titanium,then TiI4 reacted with crude titanium to synthesize TiI2,and meanwhile TiI2 decomposed at 1 200-1400K.Surface morphology,micro-area chemical composition and impurity content of the samples were analyzed by SEM,EDS and GDMS,respectively.Based on experiments and thermodynamic analysis,the temperatures in halogenation area and decomposition area and the reason for existence of Cr and Ni impurities are determined to provide a theoretical basis for the future control of metal impurity content and experimental condition optimization.
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Effect of Oxygen and Hydrogen Pretreatment on Platinum Extraction from Spent Auto-catalyst by Pressurized Hydrometallurgy

Rare Metals and Cemented Carbides | Vol., Issue 1, 2016 | pp. 15-20
A hydrometallurgical method was studied for platinum extraction from spent auto-catalyst in an autoclave,and then a process flowsheet was suggested for efficiently recovering platinum group metals from spent auto-catalyst with low energy consumption and low waste emission.Spent auto-catalyst pretreated with oxygen and hydrogen was put into a glass bottle together with hydrochloric acid,sodium chloride and sodium chlorate.And then the bottle was put into an autoclave filled with 145℃ water to extract Pt at1 013.25 kPa oxygen pressure(1 418.55 kPa total pressure).The possible reactions were proposed of platinum extraction in the autoclave.Effects were emphatically studied of redox pretreatment of spent catalyst successively with oxygen and hydrogen on Pt extraction.The results show that the platinum extraction rate of non-pretreated spent catalyst is 82%.Pretreated with O2 and H2,the spent catalyst has increased platinum extraction rate by 10% and 6%,respectively,showing that the effect of O2 pretreatment was better than that of H2 pretreatment.The optimal conditions of O2 pretreatment are 300-400 ℃ pretreatment temperature,2.0hpretreatment duration and 150-200mL/min O2 flow.The optimal conditions of H2 pretreatment are 300-600 ℃ pretreatment temperature,2.0hduration and 150-250mL/min H2 flow.The Pt extraction rate is 99% under the optimal conditions.
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New Process of Aluminum Removal from Waste Rare Earth Aluminate Trichromatic Phosphors

Rare Metals and Cemented Carbides | Vol., Issue 1, 2016 | pp. 21-24
The rare earth solution obtained by alkali fusion and acid leaching of waste rare earth aluminate trichromatic phosphors usually includes high content aluminum.Therefore,sodium or potassium organic salt selective precipitation method was presented to purify the solution,and the effects were investigated of solution pH,initial aluminum content,temperature and selective precipitant dosage on aluminum removal.Experimental results show that under the conditions of initial rare earth solution pH higher than 2.8,room temperature and atmospheric pressure and precipitant dosage more than 1.3times the theoretical amount,the concentration of residual aluminum in the solution is less than 0.22g/L,aluminum removal efficiency reaches 98.6%,and rare earth loss rate is only 0.83%.
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The Latest Development of the Tungstate Functional Materials

Rare Metals and Cemented Carbides | Vol., Issue 1, 2016 | pp. 25-29
Research progress of tungstate functional materials is reviewed.Process flowsheet is introduced of tungstate preparation with micro-emulsion method,ion exchange method and chemical precipitation method,respectively.And the applications of tungstate materials are summarized in the fields of luminescence,catalyst,photocatalyst,negative thermal expansion,corrosion,electrolyte and antibacterial.
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Technological Study of WC-6Co Nanocomposite Powder Preparation with Spray Conversion Method

Rare Metals and Cemented Carbides | Vol., Issue 1, 2016 | pp. 30-34
Using ammonium metatungstate(AMT),cobalt acetate and organic carbon as raw materials and deionized water as solvent,WC-6Co nanocomposite powder was prepared by the new technology of spray drying-calcination-ball milling-continuous reduction carbonization.Specific surface area,phase composition and morphology of the powder were analyzed by nitrogen adsorption method,X-ray diffraction(XRD)and scanning electron microscope(SEM),respectively.The effects of ball milling on the performance of W-Co composite oxide powder were investigated as well as specific surface area change of the powder during continuous reduction carbonization.The experimental results show that ball milling before continuous reduction carbonization can effectively crush the powder.And the powder has better crushing effect and more uniform particle size distribution by increasing ball to powder ratio or extending ball milling time.When the ratio and time are 10∶1and 240 min,the powder has the optimal crushing and dispersing effect with 11.62m2/g specific surface area.Ball-milled W-Co composite oxide powder is agglomerated,sintered and pre-alloyed during continuous reduction carbonization to generate WC-6Co composite powder with an average particle size of 80 nm.
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Technological Study for Preparation of High-carbon Niobium-Tungsten Alloy HCNb521

Rare Metals and Cemented Carbides | Vol., Issue 1, 2016 | pp. 35-36
The sintered bar of high-carbon niobium-tungsten alloy HCNb521 was processed by twice electron beam smelting to control carbon,zirconium and gas content in the alloy.The microstructure of the smelting ingot was investigated after high temperature annealing.And the trade-off study was made on the mechanical properties of high-carbon niobium-tungsten alloy sheet HCNb521 and ordinary niobium-tungsten alloy sheet Nb521.The results show that the increase of carbon content promotes the formation of more secondary strengthening phase in niobium-tungsten alloy to improve alloy intensity.Electron beam smelting can effectively control component content of niobium-tungsten alloy ingot.Compared with ordinary niobium-tungsten alloy,high-carbon niobium-tungsten alloy material has slightly better mechanical properties.
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