Study of Deep Separation of Tungsten from Molybdate Solution

ZHAO Zhong-wei;LI Jiang-tao;CAO Cai-fang;HUO Guang-sheng;CHEN Ai-liang;LI Hong-gui

Rare Metals and Cemented Carbides | Vol., Issue 1, 2008 | pp. 1-4

Deep separation of tungsten from molybdate solution is a problem in the field of metallurgy.According to the different properties between tungsten compound and molybdenum compound,using the theory and method of molecular design,a new reagent is used to enlarge the differences between tungsten compound and molybdenum compound.A new adsorbent is used to remove tungsten from molybdate solution.After removing tungsten,the ammonium molybdate contained WO3<0.05% is obtained by ion exchange and crystallization fro...

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Study of Phase Constitution of La_2O_3-H_3BO_3-C System During High-temperature Sintering

XU Jing-yu;WU Wen-yuan;PENG Ke-wu;TU Gan-feng

Rare Metals and Cemented Carbides | Vol., Issue 1, 2008 | pp. 5-10

Study is made of the phase constitution of La2O3-H3BO3-C system during high-temperature sintering in argon atmosphere by means of XRD and TG-DTA.The results show that dehydration of H3BO3 occurs at 82~390 ℃;in 3 steps as follows:first formation of HBO2 at 82~153 ℃,then formation of H2B4O7 in 153~222 ℃,and finally formation of B2O3 in 287~390 ℃.At 836~1 400 ℃,La2O3 and B2O3 react with C to form LaB3O6 and LaBO3;at 1 450 ℃,La2O3,B2O3 and C react into LaBO3 and B4C.At this time,LaBO3 phase is predominant.The c...

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Study of High-temperature Stability of a TiC/Ni-Al Composite Coating Prepared by Laser Deposition

QU Tong-yang;ZHAO Hai-yun;OU Yang-jie

Rare Metals and Cemented Carbides | Vol., Issue 1, 2008 | pp. 11-15

TiC/Ni-Al ceramic particle reinforced high-temperature abrasion-resistant composite coating was prepared by laser synthesis on the stainless steel substrate of 1Cr18Ni9Ti by laser deposition using Ni-Cr-Al-Co-Mo-W-Nb-Ti-C+TiC powder mixture.The sample was kept 50 hours at 1 000 ℃.Microstructures and phase composition and micro-hardness of the coatings before and after high-temperature aging were examined by OM,SEM,EDS and Vicker micro-hardness tester.Under the experimental condition,no cracks,holes or other...

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Study of Chemical Reaction and Phase Composition of B_4C and Al under High Temperature

PENG Ke-wu;WU Wen-yuan;XU Jing-yu;TU Gan-feng

Rare Metals and Cemented Carbides | Vol., Issue 1, 2008 | pp. 16-19

In this paper,systematic study is made of the high-temperature chemical reaction and phase composition of B4C and Al through XRD and differential thermal analysis.The results showed that at 0~1 500 ℃,reaction between B4C and Al resulted in Al3BC,AlB2,Al4C3 and AlB12C2 in 3 steps as follows:formation of Al3BC,AlB2 at 625~690 ℃;formation of Al4C3 at 1 150~1 185 ℃ and the formation of AlB12C2 at 1 320~1 350 ℃.The phase composition of B4C/Al composites fabricated by pressureless infiltration was analyzed,and th...

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Influence of Sintering Aids on Sintering Performance of B_4C/B-Al

WANG Dong-shan;XUE Xiang-xin

Rare Metals and Cemented Carbides | Vol., Issue 1, 2008 | pp. 20-23

The influences of sintering aids Al2O3-Y2O3on sintering performance of B4C/B-Al composites were studied in vacuum carbon tube furnace under argon atmosphere at 1 850 ℃ holding 1.5 h.The results indicated that physical mechanical properties of B4C/B-Al composites are improved through adding Al2O3-Y2O3.Comparing to samples without sintering aids the volume density of the samples increase 26.94%,porosity decreases 32.1%,and compression increases 85.81% averagely.At the same time it was pointed out that the sin...

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Research on Preparation of High-purity Ta/Nb Chlorides

HU Hua-ye;LIU Zhi-qiang

Rare Metals and Cemented Carbides | Vol., Issue 1, 2008 | pp. 24-25

High-purity Ta/Nb chlorides are obtained from Ta/Nb oxides with suitable reductant or directly from Ta/Nb carbides in the enclosed reactor by cloridizing and distillation at controlled temperature.

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Study on the Influence of Steady Electromagnetic Field on Iron Phase of the Casting Eutectic Al-Si Alloy

YOU Jing;WANG Yao-wu;FENG Nai-xiang;YANG Ming-sheng;WU Xiao-lei;DI Yue-zhong;DU Jin-jing

Rare Metals and Cemented Carbides | Vol., Issue 1, 2008 | pp. 26-30

After refined and diluted,Fe is the main impurity in the coarse aluminum-silicon alloy produced by carbothermal reduction.The efficiency of traditional iron removal by filtration with de-ironing additive is low.Study is made on the influence of electromagnetic field on iron-rich phase of the Al-Si alloy with Mn as de-ironing additive.The results showed that the iron phase in the Al-Si alloy grew up from the acicular phase to sheet and spherical phase after treated by steady electromagnetic field.The cubage ...

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The Influence of Different Gas Sources on the Preparation of the Carbon Potential of the Controllable Atmosphere Generator

LI Wei;SHI Zhang-ming;WANG Hong-cai

Rare Metals and Cemented Carbides | Vol., Issue 1, 2008 | pp. 31-33

In view of the influence of the producing gas compositions on the carbon potential,analysis is made of the carbon potential of the endorthermic controllable atmosphere generator with different gas.The results showed the natural gas is better than propane when natural gas or propane is used for controllable atmosphere.

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Impact of Different Pressure on the Properties of Me-DLC

NIE Jun-lan;GU Kun-ming;TANG Jiao-ning;MAI Da-yu;FAN Fan

Rare Metals and Cemented Carbides | Vol., Issue 1, 2008 | pp. 34-37

In the paper is introduced DLC film preparation new method of ECR(electron cyclontron resonance) by microwave plasma gas deposition in combination with magnetron sputtering.Carbon films with Ti/TiN/TiN(N,C)intermediate layer were fabricated on stainless steel substrates by sputtering graphite target and Ti target.Study is made on the influence of the gas flowrate on the film surface morphology,hardness,friction and wearing property and surface energy.

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Research on the Process for Production of High-quality Coarse-Grained WC

LUO Bin-hui;ZHANG Hua-ming

Rare Metals and Cemented Carbides | Vol., Issue 1, 2008 | pp. 38-41

Research is made on the process for production of high-quality coarse-grained WC.Through contrast test,the influence of W powder particle size and addition of active catalyst on WC particle size is analyzed and technologic parameters of production of high-quality coarse grained WC is defined.The actual performance showed that the process can effectively solve the problems outstanding in the traditional process in respect of too much consumption of raw and auxiliary materials and energy and low rate up-to gr...

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