Preparation of high purity high dense polycrystal CeB6 block cathode material

A cathode material, high-purity technology, applied in the direction of boron/boride, metal boride, etc., can solve the problems of affecting the emission performance of materials, low bulk purity, and high production cost, saving sintering time, improving purity, and improving Density effect

Inactive Publication Date: 2009-02-25
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The whole process has to go through powder crushing, pickling, water washing, drying and screening, and then long-term high-temperature sintering. The process is cumbersome, difficult to master, and the production cost is high.
And the prepared CeB 6 The purity of the block is often not high, the density is only 80-92%, and the coarse grain (tens to hundreds of microns) seriously affects the emission performance of the material, limiting the CeB 6 Applications

Method used

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  • Preparation of high purity high dense polycrystal CeB6 block cathode material
  • Preparation of high purity high dense polycrystal CeB6 block cathode material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] 1) Vacuumize the reaction chamber of the DC arc evaporation and condensation equipment to 3.0×10 -3 After Pa, fill in hydrogen and argon with a volume ratio of 3:1 and a total pressure of 0.1MPa, with metal tungsten as the cathode and elemental cerium block as the anode, under the conditions of reaction current 80A, arc voltage 45V, and reaction time 20min Prepare the cerium hydride nanopowder whose particle size is 20-40nm;

[0020] 2) After grinding and mixing cerium hydride nanopowder and boron powder (20-50nm) in a pretreatment chamber with an oxygen content of 10ppm according to a mass ratio of 1:0.456, put them into a graphite mold;

[0021] 3) Put the graphite mold into the SPS sintering equipment for sintering. The sintering process is as follows: the sintering atmosphere is a vacuum of 5Pa, the sintering pressure is 30MPa, the sintering temperature is 1300°C, the heating rate is 80°C / min, and the heat preservation is 20min. Cooling to obtain high-purity and hi...

Embodiment 2

[0024] 1) Vacuumize the reaction chamber of the DC arc evaporation and condensation equipment to 5.0×10 -3 After Pa, fill it with hydrogen and argon with a volume ratio of 1:1 and a total pressure of 0.1MPa, with metal tungsten as the cathode and elemental metal cerium as the anode, under the conditions of reaction current 150A, arc voltage 20V, and reaction time 30min Prepare the cerium hydride nanopowder whose particle size is 30~60nm;

[0025] 2) After grinding and mixing cerium hydride nanopowder and boron powder (20-50nm) in a pretreatment chamber with an oxygen content of 50ppm according to a mass ratio of 1:0.456, put them into a graphite mold;

[0026] 3) Put the graphite mold into the SPS sintering equipment for sintering. The sintering process is as follows: the sintering atmosphere is a vacuum of 5Pa, the sintering pressure is 50MPa, the sintering temperature is 1500°C, the heating rate is 140°C / min, and the heat preservation is 12min. Cooling to obtain high-purity...

Embodiment 3

[0029] 1) Vacuumize the reaction chamber of the DC arc evaporation and condensation equipment to 1.0×10 -2 After Pa, fill in hydrogen and argon with a volume ratio of 4:1 and a total pressure of 0.1MPa, with metal tungsten as the cathode and elemental metal cerium as the anode, under the conditions of reaction current 90A, arc voltage 30V, and reaction time 40min Prepare the cerium hydride nano-powder whose particle size is 20-50nm;

[0030] 2) Grinding and mixing cerium hydride nanopowder and boron powder (2-10 μm) in a pretreatment chamber with an oxygen content of 80 ppm according to a mass ratio of 1:0.456, and then putting them into a graphite mold;

[0031] 3) Put the graphite mold into the SPS sintering equipment for sintering. The sintering process is as follows: the sintering atmosphere is 0.1MPa high-purity argon atmosphere with a purity of 99.999%, the sintering pressure is 60MPa, the sintering temperature is 1700°C, and the heating rate is 200 ℃ / min, hold for 3 mi...

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Abstract

A method for preparing a high-purity and high-density polycrystalline CeB6 cathode material pertains to the technical field of rare earth boride cathode materials. The existing preparation process of the CeB6 is complicated, and the obtained sample has low purity and poor density. The method comprises the following steps: cerium hydride nano-powder is prepared by a DC arc evaporation condensation process, then the cerium hydride nano-powder and boron powder are mixed by grinding in a hypoxia environment, and sintered in vacuum or a high-purity argon atmosphere by a discharge plasma sintering technology to obtain the polycrystalline CeB6 cathode material. The method has the advantages of simple process and low sintering temperature, and that the prepared cathode material has high purity, good density, high chemical purity and excellent emission performance.

Description

technical field [0001] The invention belongs to the technical field of rare earth boride cathode materials, and in particular relates to a high-purity and high-density polycrystalline CeB 6 Preparation method of bulk cathode material. Background technique [0002] CaB 6 It has the excellent properties of rare earth metal hexaborides, such as high melting point, high hardness, low electron work function, low volatility, strong anti-poisoning ability, strong ion bombardment resistance, etc. and LaB 6 Same, CeB 6 It is an ideal hot cathode material, which is used in electron microscope, plasma source, electron beam welding machine, electron beam exposure machine, field emission array and other equipment. [0003] Recent studies have shown that CeB 6 As a hot cathode material, LaB, which is recognized as the best cathode among rare earth borides 6 Compared with LaB, it has several more excellent characteristics, one is strong resistance to carbon pollution, and the other i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B35/04
Inventor 张久兴周身林刘丹敏
Owner BEIJING UNIV OF TECH
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