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Preparation method of nuclear-grade boron carbide pellet

A boron carbide and pellet technology, which is used in manufacturing tools, ceramic molding machines, etc., can solve problems such as difficulty in control, grain growth, loss of sintering molds, etc., and achieve a complete structure, stable performance, and good physical and mechanical properties. Effect

Active Publication Date: 2021-11-26
CHINA INSTITUTE OF ATOMIC ENERGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Under the same density requirements, too high sintering temperature or pressure will cause excessive loss of sintering mold, or cause abnormal grain growth, which is difficult to control

Method used

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  • Preparation method of nuclear-grade boron carbide pellet
  • Preparation method of nuclear-grade boron carbide pellet
  • Preparation method of nuclear-grade boron carbide pellet

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Such as figure 1 Shown, a kind of preparation method of nuclear grade boron carbide pellet, comprises the steps:

[0025] (1) Loading and assembly: put 10 Boron carbide raw material powder with B enrichment degree ≥ 85% is filled in a mold that conforms to the shape and structure of the desired boron carbide pellet product, wherein the sum of the mass fractions of boron carbide and free boron in the boron carbide raw material powder is ≥ 98.5% , the median particle size D of boron carbide raw material powder 50 is 0.712 μm.

[0026] (2) Cold press preforming: use a hydraulic press to cold press the mold filled with boron carbide raw material powder, and hold the pressure at a forming pressure of 4.5 MPa for 8 minutes to make a preformed boron carbide pellet.

[0027] (3) Heating and pressure sintering: 1) Place the preformed boron carbide core block in a sintering mold made of graphite, put it into a vacuum furnace, evacuate the vacuum furnace to below 10Pa, and rais...

Embodiment 2

[0029] Such as figure 1 Shown, a kind of preparation method of nuclear grade boron carbide pellet, comprises the steps:

[0030] (1) Loading and assembly: put 10 Boron carbide raw material powder with B enrichment degree ≥ 85% is filled in a mold that conforms to the shape and structure of the desired boron carbide pellet product, wherein the sum of the mass fractions of boron carbide and free boron in the boron carbide raw material powder is ≥ 98.5% , the median particle size D of boron carbide raw material powder 50 is 0.865 μm.

[0031] (2) Cold press preforming: use a hydraulic press to cold press the mold filled with boron carbide raw material powder, and hold the pressure for 10 minutes at a forming pressure of 3 MPa to make a preformed boron carbide pellet.

[0032](3) Heating and pressure sintering: 1) Place the preformed boron carbide core block in a sintering mold made of graphite, put it into a vacuum furnace, evacuate the vacuum furnace to below 10Pa, and raise ...

Embodiment 3

[0034] Such as figure 1 Shown, a kind of preparation method of nuclear grade boron carbide pellet, comprises the steps:

[0035] (1) Loading and assembly: put 10 Boron carbide raw material powder with B enrichment degree ≥ 85% is filled in a mold that conforms to the shape and structure of the desired boron carbide pellet product, wherein the sum of the mass fractions of boron carbide and free boron in the boron carbide raw material powder is ≥ 98.5% , the median particle size D of boron carbide raw material powder 50 is 0.632 μm.

[0036] (2) Cold press preforming: use a hydraulic press to cold press the mold filled with boron carbide raw material powder, and hold the pressure for 5 minutes at a forming pressure of 6 MPa to make a preformed boron carbide pellet.

[0037] (3) Heating and pressure sintering: 1) Place the preformed boron carbide core block in a sintering mold made of graphite, put it into a vacuum furnace, evacuate the vacuum furnace to below 10Pa, and raise ...

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Abstract

The invention relates to a preparation method of a nuclear-grade boron carbide pellet. By adopting the preparation method of the nuclear-grade boron carbide pellet provided by the invention, the nuclear-grade boron carbide pellet of which the density is 2.1-2.2 g / cm < 3 > and the 10B enrichment degree is greater than 85% can be obtained through hot pressing sintering of the 10B boron carbide powder, so that the obtained nuclear-grade boron carbide pellet can meet a neutron absorption function required by reactivity control of a research nuclear reactor. Meanwhile, the prepared nuclear-grade boron carbide pellet has high physical and mechanical properties, can ensure that the pellet is complete in structure and stable in performance and operates under various working conditions of high temperature, irradiation, impact, vibration and the like within the service life of a reactor, and is used as a neutron absorber pellet in a domestic research reactor control rod assembly.

Description

technical field [0001] The invention belongs to the field of preparation of nuclear reactor control rod component materials, and relates to a preparation method of nuclear-grade boron carbide pellets. Background technique [0002] Boron carbide (B 4 C) Because of its large neutron absorption cross-section and good radiation stability, it is a commonly used neutron absorption control material for nuclear reactors. B has 10 B and 11 B two isotopes, natural B 10 B accounts for about 19.8at% and 80.2at% of 11 B hardly absorbs neutrons, only 10 B can absorb neutrons. Boron carbide is an extremely difficult to sinter and dense ceramic material with a density of up to 2.55g / cm 3 At present, the preparation of boron carbide pellets mostly adopts two methods: hot pressing sintering and atmospheric pressure sintering, each with its own advantages and disadvantages. The boron carbide products produced by steel mold forming and atmospheric pressure sintering process have low den...

Claims

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Application Information

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IPC IPC(8): C04B35/563C04B35/645B28B3/20
CPCC04B35/563C04B35/645B28B3/20C04B2235/658C04B2235/5445C04B2235/786C04B2235/77C04B2235/9607C04B2235/96Y02E30/30
Inventor 郭志家杨历军刘天才范月容张金山冯嘉敏彭朝晖衣大勇孙征吕征王亚婷赵守智柯国土陈会强姚成志周寅鹏石辰蕾朱磊江浩刘宗泉
Owner CHINA INSTITUTE OF ATOMIC ENERGY
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