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Method for preparing boron nitride ceramic material through stepped sintering

A ceramic material and step-by-step sintering technology, which is applied in the field of step-by-step sintering to prepare boron nitride ceramic materials, can solve the problems of difficult discharge of impurities such as gases, affect the density and strength of ceramic materials, and complex processes, and achieve the goal of increasing density and strength. Effect

Inactive Publication Date: 2017-01-04
长兴鑫宇耐火材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The current conventional hot pressing process for preparing boron nitride involves the forming, heating, and pressing of the green body, and the process is long and complicated.
Moreover, in the current preparation process, under the multiple effects of temperature and pressure, impurities such as gases in the powder will be difficult to discharge, which will affect the density and strength of the final ceramic material.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Prepare boron nitride-based powder, wherein the additive is SiC, the content is 20wt.%, the sintering aid is B2O3, the content is 8wt.%, boron nitride is the balance, and several powders are mixed evenly.

[0022] The mixed powders are put into graphite molds for hot pressing and sintering.

[0023] In the hot pressing sintering step, the low temperature holding step is 600°C, and the holding time is 1.5 hours; the medium temperature holding step is 1300°C, the pressure is 18MPa, and the holding time is 2 hours; the high temperature holding step is 1800°C, the pressure is 20MPa, and the holding time The time is 2 hours.

[0024] The material after sintering is taken out to obtain boron nitride ceramic material.

Embodiment 2

[0026] Prepare boron nitride-based powder, wherein the additive is Si4N3, the content is 20wt.%, the sintering aid is B2O3, the content is 8wt.%, boron nitride is the balance, and several powders are mixed evenly.

[0027] The mixed powders are put into graphite molds for hot pressing and sintering.

[0028] In the hot pressing sintering step, the low temperature holding step is 800°C, and the holding time is 1.5 hours; the medium temperature holding step is 1200°C, the pressure is 20MPa, and the holding time is 2 hours; the high temperature holding step is 1900°C, the pressure is 18MPa, and the holding time The time is 1.5 hours.

[0029] The material after sintering is taken out to obtain boron nitride ceramic material.

Embodiment 3

[0031] Prepare boron nitride-based powder, in which the additive is CaO, the content is 18wt.%, the sintering aid is B2O3, the content is 8wt.%, boron nitride is the balance, and several powders are mixed evenly.

[0032] The mixed powders are put into graphite molds for hot pressing and sintering.

[0033] In the hot pressing sintering step, the low temperature holding step is 700°C, and the holding time is 1.5 hours; the medium temperature holding step is 1500°C, the pressure is 18MPa, and the holding time is 2 hours; the high temperature holding step is 1900°C, the pressure is 20MPa, and the holding time The time is 1.2 hours.

[0034] The material after sintering is taken out to obtain boron nitride ceramic material.

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PUM

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Abstract

The invention relates to a method for preparing aboron nitride ceramic material through stepped sintering and belongs to the field of insulating material preparation. The method comprises the steps of firstly mixing BN-based powder, additive and sintering aid and performing granulation; then containing the mixed powder into a graphite mold and then performing stepped hot-pressed sintering; and obtaining the boron nitride ceramic material after sintering. In the method, the hot-pressed sintering process comprises a low-temperature vacuum maintaining step, a medium-temperature nitrogen pressure maintaining step and a high-temperature inert atmosphere pressure maintaining step. By adopting the process, the discharge of gas impurities can be effectively facilitated and the density and strength of the boron nitride ceramic material are improved.

Description

technical field [0001] The invention relates to a method for preparing boron nitride ceramic materials by step-by-step sintering, which belongs to the field of insulating material preparation. Background technique [0002] Boron nitride is commonly known as white graphite. It has similar properties to graphite and is white in texture. There are two crystal forms: hexagonal and cubic, usually in a hexagonal structure. Under the special conditions of high temperature and ultra-high pressure, the hexagonal crystal form can be transformed into a cubic crystal form. Among them, hexagonal boron nitride is widely used, and its powder can be used as an excellent lubricant and release agent, while ceramics can be used as crucibles, boats, liquid metal delivery pipes, rocket nozzles, high-power device bases, and semiconductors for smelting and evaporating metals. Component doping sources, and various high-temperature (high-voltage, high-frequency) insulating and heat-dissipating comp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/583C04B35/645
CPCC04B35/583C04B35/645C04B2235/3208C04B2235/3217C04B2235/3225C04B2235/3244C04B2235/3409C04B2235/3826C04B2235/3873C04B2235/6562C04B2235/6567
Inventor 钱建军
Owner 长兴鑫宇耐火材料有限公司
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