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In-situ synthesized silicon nitride/zirconium boride composite ceramic and preparation method and application thereof

A technology of complex phase ceramics and in-situ synthesis, which is applied in the field of ceramic materials, can solve problems such as the difficulty of nitriding Si powder, and achieve the effects of enhanced conductivity, increased hardness, and improved mechanical properties

Active Publication Date: 2019-12-10
GUANGDONG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Based on the difficulty of nitriding Si powder above, at present, ZrO is mainly added to Si powder. 2 、TiO 2 , rare earth oxides, etc. are used as catalysts to promote nitriding, but in the existing technology, Si is only prepared by Si powder reaction sintering. 3 N 4 Ceramics, however, considering some occasions that require higher hardness and conductivity, the existing technology cannot meet

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] 1. Using Si powder (particle size 1μm) as raw material, with 10% ZrB 2 (particle size of 0.1 μm) as the second phase, the pretreated ZrB at 1000 ° C for 10 h 2 , 5% MgO powder (purity 99.9%) and 5% Y 2 o 3 Powder (purity is 99.9%) is used as additive for batching, with ethanol as solvent, with Si 3 N 4 The ball is the ball milling medium, mixed on the ball mill for 8 hours, and after the ball milling mixture is dried, a uniform Si-ZrB 2- MgO-Y 2 o 3 Mix powder.

[0027] 2. Si-ZrB 2 -MgO-Y 2 o 3 Put the mixed powder into a mold for molding to obtain a green body, and then pass cold isostatic pressing at a pressure of 200MPa for 5 minutes to obtain Si-ZrB 2 -MgO-Y 2 o 3 body.

[0028] 3. Si-ZrB 2 -MgO-Y 2 o 3 Put the green body into a graphite crucible, heat it up to 1400°C at a rate of 20°C / min and keep it for 2h, the atmosphere is nitrogen at 1atm, then raise the temperature at a rate of 10°C / min to 1500°C and keep it at 4h, the atmosphere is nitrogen at...

Embodiment 2

[0031] The difference from Example 1 is that the pretreated ZrB 2 , Si powder, MgO, Yb 2 o 3The mass ratio of the powder is 40:55:2.5:2.5 for batching, wherein, firstly, the temperature is raised to 1300°C for 4 hours, and then the temperature is raised to 1500°C for 2 hours to obtain Si 3 N 4 -ZrB 2 ceramics.

[0032] Prepared Si 3 N 4 -ZrB 2 The relative density of the ceramic is 99%, the hardness of the material is 25GPa, and the fracture toughness is 10MPa m 1 / 2 , The bending strength is 1200MPa.

Embodiment 3

[0034] The difference from Example 1 is that the pretreated ZrB 2 , Si powder, MgO, Yb 2 o 3 The powder mass ratio is 20:75:2.5:2.5 for batching, among which, firstly, the temperature is raised to 1450 ° C for 0.5 h, and then the temperature is raised to 1600 ° C for 1 h to obtain Si 3 N 4 -ZrB 2 ceramics.

[0035] Prepared Si 3 N 4 -ZrB 2 The relative density of the ceramic is 99%, the hardness of the material is 20GPa, and the fracture toughness is 12MPa m 1 / 2 , The bending strength is 1000MPa.

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Abstract

The invention belongs to the technical field of ceramic materials, and discloses an in-situ synthesized silicon nitride / zirconium boride composite ceramic and a preparation method and application thereof. The silicon nitride / zirconium boride composite ceramic is prepared according to the following steps: preoxidized ZrB2, Si powder and a sintering assistant MgO-Y2O3 are mixed and dried to obtain Si- ZrB2-MgO-Y2O3 mixed powder; the mixed powder is pelletized and molded, and then cold isostatic pressing is carried out to obtain a Si-ZrB2-MgO-Y2O3 blank; and the blank is sintered at 1300-1450 DEGC in nitrogen atmosphere through heating, then sintered at 1500-1600 DEG C, and heat preservation is carried out. The relative density of the Si3N4-ZrB2 composite ceramic prepared by the method of the invention is 95-99%, the hardness is 18-25 GPa, the fracture toughness is 10-15 MPa.m<1 / 2>, and the bending strength is 800-1200 MPa.

Description

technical field [0001] The invention belongs to the technical field of ceramic materials, and more specifically relates to an in-situ synthesis of silicon nitride / zirconium boride (Si 3 N 4 -ZrB 2 ) Composite ceramics and their preparation methods and applications. Background technique [0002] Si 3 N 4 As a structural ceramic, ceramics have excellent properties such as high strength, high hardness, high toughness, wear resistance, high temperature resistance, and high thermal conductivity, and are widely used in the industry. Usually Si 3 N 4 Ceramics with high purity Si 3 N 4 Powder is used as raw material, and sintering aids are added to promote densification, but this method has high preparation costs. [0003] In recent years, although Si powder is used as raw material, Si powder is prepared by reactive pressure sintering. 3 N 4 Ceramics, lower costs. However, since the nitriding speed of Si powder is relatively slow, and the Si formed after nitriding 3 N ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/58C04B35/584C04B35/622C04B35/626C04B35/64
CPCC04B35/58078C04B35/584C04B35/622C04B35/62605C04B35/64C04B2235/6562C04B2235/6567C04B2235/96
Inventor 詹创添吴利翔牛文彬朱林林郭伟明林华泰
Owner GUANGDONG UNIV OF TECH
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