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A kind of preparation method of lanthanum hexaboride whisker

A technology of lanthanum hexaboride and whiskers, which is applied in the field of preparation of lanthanum hexaboride whiskers, can solve the problems of excessively large specific surface area of ​​aluminum flux, unfavorable growth of lanthanum hexaboride whiskers, and reduced production efficiency, and the like. Easy-to-achieve, easy-to-obtain, high-quality results for growing conditions

Active Publication Date: 2020-09-08
INST OF ELECTRICAL ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, in the process of preparing lanthanum hexaboride by the flux method in the past, the prepared ingredients were directly sintered in a high-temperature furnace, and there were some problems: first, the added aluminum flux was granular, so The total specific surface area of ​​the aluminum flux is too large, and a dense aluminum oxide film is formed on the surface after contacting with the air, so that after the aluminum is oxidized in the furnace, it is wrapped by the oxide film on the surface, and it is difficult to contact with the metal lanthanum powder and boron powder, thus greatly The production efficiency is reduced, which is also the biggest problem in the preparation of lanthanum hexaboride whiskers by the aluminum co-solvent method; secondly, due to the excessive amount of aluminum, the raw material lanthanum powder and boron powder are too dispersed in the aluminum co-solvent, which is not conducive to growing larger The lanthanum hexaboride whiskers; finally, after the sintering is completed, the grown lanthanum hexaboride whiskers are distributed in various parts of the aluminum block, and it is necessary to dissolve all the aluminum blocks to purify, which takes too long and is inefficient

Method used

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  • A kind of preparation method of lanthanum hexaboride whisker
  • A kind of preparation method of lanthanum hexaboride whisker
  • A kind of preparation method of lanthanum hexaboride whisker

Examples

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Effect test

Embodiment 1

[0029] In the glove box, first remove the black oxide film on the surface of the metal lanthanum rod to expose the silver metal lanthanum. Then file 2 g of metal lanthanum powder and mix it with 1 g of boron powder. Put the metal lanthanum powder and boron powder into a mortar and grind for 30 minutes, so that the metal lanthanum powder and boron powder are fully mixed. Add 20g of aluminum particles into the alumina crucible, then pour the evenly mixed ingredients into the crucible, shake gently so that the ingredients are filled into the gaps of the aluminum particles, and then add 7g of aluminum particles to cover the surface of the metal lanthanum powder and boron powder. Put the alumina crucible into the induction heating device, raise the temperature to 700°C in an environment with a vacuum degree of 3pa, and stop heating after the aluminum particles are fully melted. Then put the alumina crucible into the furnace for sintering, adjust the heating rate to 100°C / h, raise t...

Embodiment 2

[0032] In the glove box, first remove the black oxide film on the surface of the metal lanthanum rod to expose the silver metal lanthanum. Then file 3 g of metal lanthanum powder and mix it with 1.5 g of boron powder. Put the metal lanthanum powder and boron powder into a mortar and grind for 30 minutes, so that the metal lanthanum powder and boron powder are fully mixed. Put 14g of metal aluminum in the alumina crucible, then put it into the induction heating device, and heat it under the environment with a vacuum degree of 3pa. After the aluminum block melts, stop heating and take out the alumina crucible. Add 2.25g metal lanthanum powder and boron powder on the aluminum layer, and then add 14g aluminum on the metal lanthanum powder and boron powder, put it into an induction heating device and heat it under a vacuum degree of 3pa. Repeatedly, a material structure with three layers of aluminum sandwiched between two layers is obtained. Then put the crucible into the furnace ...

Embodiment 3

[0035]In the glove box, first remove the black oxide film on the surface of the metal lanthanum rod to expose the silver metal lanthanum. Then file 3 g of metal lanthanum powder and mix it with 1.5 g of boron powder. Put the metal lanthanum powder and boron powder into a mortar and grind for 30 minutes, so that the metal lanthanum powder and boron powder are fully mixed. Put 30g of metallic aluminum in an alumina crucible, then put it into an induction heating device, and heat it in an environment with a vacuum degree of 3pa. After the aluminum block melts, stop heating and take it out. After cooling, punch holes in the vertical direction of the aluminum block, fill the holes with metal lanthanum powder and boron powder, and cover the 10g aluminum block on the metal lanthanum powder and boron powder. Then, put the crucible into the furnace for sintering, adjust the heating rate to 100°C / h, raise the temperature to 1350°C and keep it for 12 hours, and the cooling rate is 100°C / ...

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Abstract

The invention discloses a preparation method of lanthanum hexaboride crystal whiskers. Metal lanthanum powder and boron element powder is taken as a reaction raw material, metal aluminum is taken as afluxing agent, the metal lanthanum powder and the boron element powder are fully mixed and ground uniformly, certain amount of the metal aluminum is added, and the metal aluminum fluxing agent is treated through special methods of a gap filling method, a layering method and a hole drilling method to remove an oxidation film on the surface of aluminum, allow raw materials to be relatively concentrated and reduce purifying time, and therefore the preparation efficiency of the lanthanum hexaboride crystal whiskers is improved.

Description

technical field [0001] The invention relates to a preparation method of lanthanum hexaboride whiskers. Background technique [0002] Due to its unique structural characteristics, lanthanum hexaboride determines its special properties. Six smaller boron atoms form an octahedral framework structure, and this framework structure of eight borons wraps larger lanthanum atoms at the eight vertices of the cube. This unique structure determines that it has a higher melting point, greater hardness, better chemical stability and thermal stability, and has good electrical conductivity and low work function, and it is resistant to ion bombardment Strong, good anti-poisoning, long life and so on. Therefore, lanthanum hexaboride is a good hot cathode electron source, which is widely used in transmission electron microscopy, scanning electron microscopy and electron beam processing equipment and other fields. Lanthanum hexaboride has been successfully prepared in powder, block and needl...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C30B29/10C30B29/62C30B9/12
CPCC30B9/12C30B29/10C30B29/62
Inventor 缪加巍伍岳高召顺肖立业韩立刘俊标左婷婷
Owner INST OF ELECTRICAL ENG CHINESE ACAD OF SCI
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