Nanocrystalline silicon carbide superhard block and preparation method thereof

A technology of silicon carbide and nanocrystals, which is applied in the field of nanocrystalline silicon carbide superhard blocks and its preparation, to achieve the effects of improving density and hardness, improving activity, and great application potential

Active Publication Date: 2022-04-12
YANSHAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, in these cases, the use of amorphous materials is very disadvantageous

Method used

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  • Nanocrystalline silicon carbide superhard block and preparation method thereof
  • Nanocrystalline silicon carbide superhard block and preparation method thereof
  • Nanocrystalline silicon carbide superhard block and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0068] 0.3 g of silicon carbide raw material (average grain size: 5 nm) was treated with 10% hydrofluoric acid, and the pickling time was 60 min. The acid solution is diluted with deionized water, and a combination of centrifuge and ultrasonic cleaner is used in this process. The acid liquid is separated from the raw material by centrifugation, and the raw material is mixed evenly with the newly added deionized water by ultrasonic. Repeat several times until the pH is close to 7. The centrifuge speed is 4000r / min, the centrifugation time is 15min, and the ultrasonic time is 5min. The raw materials obtained by the last centrifugation were dried at a temperature of 60° C. for 18 hours.

[0069] Apply a pressure of 10MPa to the dried powder to prefabricate a cylindrical body with a diameter of 3.5mm and a height of 3mm, put it into a hexagonal boron nitride crucible, and put the assembly block into a domestic hexagonal top synthesis device , sintering under the conditions of p...

Embodiment 2

[0071] 0.3 g of silicon carbide raw material (average grain size: 30 nm) was treated with 10% hydrofluoric acid, and the pickling time was 30 min. The acid solution is diluted with deionized water, and a combination of centrifuge and ultrasonic cleaner is used in this process. The acid liquid is separated from the raw material by centrifugation, and the raw material is mixed evenly with the newly added deionized water by ultrasonic. Repeat several times until the pH is close to 7. The centrifuge speed is 11000r / min, and the centrifugation time is 20min. Ultrasonic time is 10min. Dry the raw material obtained from the last centrifugation. The drying temperature is 40°C and the drying time is 24h.

[0072] Apply 10MPa pressure to the dried powder to prefabricate a cylindrical body with a diameter of 1.2mm and a height of 2.3mm, put it into a hexagonal boron nitride crucible, put the assembled block into a T25 press, and press 15GPa, sintering at a temperature of 1500°C, and...

Embodiment 3

[0074] 0.15 g of silicon carbide raw material with an average grain size of 5 nm and 0.15 g of silicon carbide raw material with an average grain size of 70 nm were mixed. The mixed raw material was treated with 10% hydrofluoric acid. Pickling time is 45min. The acid solution is diluted with deionized water, and a combination of centrifuge and ultrasonic cleaner is used in this process. The acid liquid is separated from the raw material by centrifugation, and the raw material is mixed evenly with the newly added deionized water by ultrasonic. Repeat several times until the pH is close to 7. The rotational speed of the centrifuge is 11000r / min, and the centrifugation time is 15min. Ultrasonic time is 5min. Dry the raw material obtained from the last centrifugation. The drying temperature is 40°C, and the drying time is 24 hours.

[0075] Apply 10MPa pressure to the dried powder to prefabricate a cylindrical body with a diameter of 1.2mm and a height of 2.3mm, put it into ...

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Abstract

The invention relates to a nanocrystalline silicon carbide superhard block and a preparation method thereof. The average grain size of the nanocrystalline silicon carbide superhard block is smaller than 100 nm, and the Vickers hardness is equal to or higher than 40 GPa. The preparation method comprises the following steps: A) pretreatment: weighing a certain mass of silicon carbide nano-powder, performing acid pickling treatment, diluting with water until the silicon carbide nano-powder is nearly neutral, and then taking out and drying the silicon carbide nano-powder; b) pre-pressing molding: pre-pressing the raw materials pretreated in the step A) to obtain a pre-pressed green body; c) sintering: performing high-temperature and high-pressure sintering on the pre-pressed green body obtained in the step B); the high-temperature and high-pressure sintering equipment in the step C is subjected to cooling and pressure relief, sintered silicon carbide blocks are taken out and subjected to optional aftertreatment, and the nanocrystalline silicon carbide superhard blocks are obtained.

Description

technical field [0001] The application belongs to the field of inorganic non-metallic materials, and in particular relates to a nanocrystalline silicon carbide superhard block material and a preparation method thereof. Background technique [0002] Materials with a Vickers hardness exceeding 40 GPa are called superhard materials. Superhard materials are widely used in cutting, turning, grinding and other industrial fields. In the 1950s, people had successfully synthesized diamond and cubic boron nitride. However, so far, superhard materials are still limited to these two families. Researchers have made tireless efforts to obtain superhard materials other than diamond and cubic boron nitride, but with little return. At the same time, the method of nanostructure is widely used to improve the hardness of diamond and cubic boron nitride materials. For example, by reducing the grain size of cubic boron nitride to 14nm, its hardness can be increased to 85GPa, which is twice the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/565C04B35/622C04B35/645
Inventor 高国英孙荣鑫魏旭东武英举王霖于栋利徐波田永君
Owner YANSHAN UNIV
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