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High-performance nano silicon carbide ceramic as well as preparation method and application thereof

A technology of nano-silicon carbide and silicon carbide ceramics, which is applied in the field of high-performance nano-silicon carbide ceramics and its preparation, can solve problems such as restricting the application of silicon carbide ceramics, affecting the performance of finished materials, and reducing the sintering temperature, so as to ensure strength and improve production Efficiency, effect of low sintering temperature

Active Publication Date: 2020-12-11
GUANGDONG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, due to the strong covalent bond of silicon carbide, its melting point is very high, its sintering process is poor, and its density is low
The conventional hot pressing sintering temperature of silicon carbide exceeds 2000°C, resulting in coarse grains; the use of liquid phase sintering to promote densification can reduce the sintering temperature, but the introduction of more sintering aids seriously affects the performance of the finished material in high temperature applications , restricting the further application of silicon carbide ceramics

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] 1. Preparation

[0030] (1) With the polycarbosilane of yield rate 60wt% as precursor, with Al 2 o 3 -CeO 2 As a sintering aid, polycarbosilane, Al 2 o 3 with CeO 2 The mass percentages are 96%, 2% and 2%, respectively. Mix polycarbosilane and sintering aid, use Si 3 N 4 The balls were milled and mixed for 8 hours at a speed of 150 r / min under a roller ball mill to obtain a mixed powder;

[0031] (2) Under a nitrogen atmosphere, pressurize at 10 MPa, first raise the temperature at 2°C / min to 200°C for 1 hour, then raise the temperature at 10°C / min to 800°C and hold for 1 hour to obtain the cracked product;

[0032] (3) The cleavage product is subjected to ball milling and granulation treatment, with absolute ethanol as solvent, using Si 3 N 4 The balls are milled in a roller type, and the ball milling is performed at a rotation speed of 400 r / min for 24 hours, and the slurry after the mixing is completed is dried.

[0033] (4) Put the dried powder into the si...

Embodiment 2

[0036] The difference from Example 1 is that in step (2), the temperature is raised to 300° C. first, and then to 1000° C. to obtain the cracked product.

[0037] The density of the nano-silicon carbide ceramics obtained in this embodiment is 97%, the Vickers hardness is 24GPa, the flexural strength is 900MPa, and the fracture toughness is 7MPa m 1 / 2 , The high temperature strength is 700MPa at 1200°C.

Embodiment 3

[0039] The difference from Example 1 is that: the axial pressure in step (5) is 50 MPa, the sintering temperature is 1500° C.; the holding time is 50 min.

[0040] Polycarbosilane precursor, Al described in step (1) 2 o 3 with CeO 2 The mass percentages are 98%, 1% and 1%, respectively.

[0041] The density of the nano-silicon carbide ceramics obtained in this embodiment is 99%, the Vickers hardness is 26GPa, the flexural strength is 1000MPa, and the fracture toughness is 9MPa m 1 / 2 , The high temperature strength at 1200°C is 800MPa.

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Abstract

The invention belongs to the field of non-oxide ceramic materials, and discloses high-performance nano silicon carbide ceramic as well as a preparation method and application thereof. The preparationmethod of the silicon carbide ceramic comprises the following steps of: ball-milling and mixing polycarbosilane serving as a precursor and a sintering aid Al2O3-CeO2, heating to 200-400 DEG C in a protective atmosphere, keeping the temperature, heating to 500-1200 DEG C, and cracking the mixture to obtain mixed powder; and carrying out ball milling and granulation on the mixed powder, putting thegranules into a graphite mold, applying pressure of 1-20 MPa, and sintering at 1200-1450 DEG C in a protective atmosphere. Through the size effect, the thickness of the sample is controlled, so that the density of the sample is 97% or above, the Vickers hardness is 25-35 GPa, the bending strength is 700-1200 MPa, the breaking tenacity is 6-12 MPa.m<1 / 2>, and the high-temperature strength at 1200 DEG C is 800-1300 MPa. The ceramic can be widely applied to the field of nuclear energy.

Description

technical field [0001] The invention belongs to the technical field of non-oxide ceramic materials, and more specifically relates to a high-performance nano-silicon carbide ceramic and its preparation method and application. Background technique [0002] The development of science and technology has put forward higher requirements for materials. The advantages of ceramic-based composite materials such as high strength, high thermal conductivity, corrosion resistance and high temperature resistance are greater than those of alloy materials. Among them, silicon carbide (SiC) The material is a typical ceramic material. Its high hardness, thermal stability and chemical corrosion resistance in high temperature environment make it widely used in high temperature parts, nuclear energy thin-walled parts and other fields. [0003] However, since silicon carbide has a strong covalent bond, its melting point is very high, its sintering process is poor, and its density is low. The conv...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/571C04B35/622C04B35/63
CPCC04B35/571C04B35/622C04B35/6303C04B2235/602C04B2235/658C04B2235/656C04B2235/6562C04B2235/96C04B2235/666C04B2235/781
Inventor 周宇章吴利翔郭伟明朱林林林华泰
Owner GUANGDONG UNIV OF TECH
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