Silicon nitride ceramic with hard outside and tough inside and preparation method thereof

A technology of silicon nitride ceramics, which is hard on the outside and tough on the inside, is applied in the field of preparation of silicon nitride ceramics, which can solve the problems of insufficient hardness and wear resistance of ceramics that cannot meet application requirements, so as to reduce the densification temperature, enhance toughness, and promote The effect of phase transition

Active Publication Date: 2022-03-11
SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, when applied in some environments with high requirements for wear resistance, the traditional Si 3 N 4 Due to the phase transformation of ceramics during the sintering process, the α-phase with intrinsically high Vickers hardness will transform into the β-phase with intrinsically high toughness but slightly lower hardness, which makes the wear resistance of ceramics insufficient during use. Unable to meet application requirements

Method used

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  • Silicon nitride ceramic with hard outside and tough inside and preparation method thereof
  • Silicon nitride ceramic with hard outside and tough inside and preparation method thereof
  • Silicon nitride ceramic with hard outside and tough inside and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] S1: Weigh 89.5g Si 3 N 4 , 0.51g Al 2 o 3 , 9.49g Er 2 o 3 and 0.5g ZrSi 2 A total of 100g, configured into a slurry with a certain solid content, and planetary ball milled at a speed of 300rpm for 4 hours; the obtained slurry was dried and ground, passed through a 100-mesh sieve, and preformed under a pressure of 5.0MPa;

[0039] S2: Put the ceramic biscuit obtained in step S1 into a graphite mold, place it in a hot pressing sintering furnace, and fill it with N 2 As a protective gas, the temperature was raised to 1750°C at a certain rate, and kept for 2 hours, and a sintering pressure of 20MPa was applied to obtain a bending strength of 1252±15.2MPa and a fracture toughness of 11.91±0.11MPa m 1 / 2 , Si with a Vickers hardness of 15.34±0.04GPa 3 N 4 ceramics;

[0040] S3: Grinding and polishing the surface of the inner layer ceramic block obtained in step S2 to obtain a flat sample with a certain surface finish;

[0041] S4: Weigh 71.5g Si 3 N 4 , 1.81g Al ...

Embodiment 2

[0046] S1: Weigh 88.5g Si 3 N 4 , 0.63g Al 2 o 3 , 9.37g Er 2 o 3 and 1.5g ZrSi 2 A total of 100g, configured into a slurry with a certain solid content, and planetary ball milled at 400rpm for 3 hours; the obtained slurry was dried and ground, passed through a 200-mesh sieve, and preformed under a pressure of 2.5MPa;

[0047] S2: Put the ceramic biscuit obtained in step S1 into a graphite mold, place it in a hot pressing sintering furnace, and fill it with N 2 As a protective gas, the temperature was raised to 1775°C at a certain rate, and kept for 2.5 hours, and a sintering pressure of 40MPa was applied to obtain a bending strength of 1384.6±24.9MPa and a fracture toughness of 13.57±0.17MPa m 1 / 2 , Si with a Vickers hardness of 14.78±0.08GPa 3 N 4 ceramics;

[0048] S3: Grinding and polishing the surface of the inner layer ceramic block obtained in step S2 to obtain a flat sample with a certain surface finish;

[0049] S4: Weigh 71.5g Si 3 N 4 , 1.65g Al 2 o 3 ...

Embodiment 3

[0053] S1: Weigh 89.5g Si 3 N 4 , 0.82g Al 2 o 3 , 9.17g Er 2 o 3 and 0.5g ZrSi 2 A total of 100g, configured into a slurry with a certain solid content, and planetary ball milled at 400rpm for 3 hours; the obtained slurry was dried and ground, passed through a 200-mesh sieve, and preformed under a pressure of 2.5MPa;

[0054] S2: Put the ceramic biscuit obtained in step S1 into a graphite mold, place it in a hot pressing sintering furnace, and fill it with N 2 As a protective gas, the temperature was raised to 1800°C at a certain rate and kept for 3 hours, and a sintering pressure of 60MPa was applied to obtain a bending strength of 1456.2±19.2MPa and a fracture toughness of 15.4±0.21MPa m 1 / 2 , Si with a Vickers hardness of 14.9±0.18GPa 3 N 4 ceramics;

[0055] S3: Grinding and polishing the surface of the inner layer ceramic block obtained in step S2 to obtain a flat sample with a certain surface finish;

[0056] S4: Weigh 71.5g Si 3 N 4 , 1.43g Al 2 o 3 , 1.5...

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Abstract

The invention relates to silicon nitride ceramic with hard outside and tough inside and a preparation method thereof. The Si3N4 ceramic with hard outside and tough inside comprises three layers of silicon nitride ceramic; wherein the middle layer is an inner layer, and the upper and lower layers are outer layers; the main phase of the inner layer is beta-Si3N4, preferably, 88-89.5 wt% of silicon nitride powder is used as a raw material, 10.5-12 wt% of Al2O3-Er2O3-ZrSi2 is used as a sintering aid, and the inner layer is prepared through hot pressed sintering; the main phase of the outer layer is alpha-Si3N4, preferably, 60.5-71.5 wt% of silicon nitride powder is used as a raw material, 8.5-9.5 wt% of Al2O3-Nd2O3-LiF is used as a sintering aid, 20-30 wt% of TiC is used as a second phase, and the outer layer is obtained through secondary hot pressing sintering.

Description

technical field [0001] The invention relates to an externally hard and internally tough Si 3 N 4 Ceramic and its preparation method, specifically, the gradient structure Si of the outer layer and inner layer with high hardness and high toughness characteristics respectively obtained by two-step hot-pressing sintering 3 N 4 Ceramics belong to the field of preparation of silicon nitride ceramics. Background technique [0002] Silicon nitride (Si 3 N 4 ) Ceramics have the advantages of low density, high hardness, high strength, high temperature resistance, wear resistance, corrosion resistance, electrical insulation and non-magnetic conductivity, etc., and can be used as bearing balls for vacuum, high temperature, high speed, low temperature, corrosion, non-conductive Magnetic and non-conductive working conditions, but also suitable for special working conditions such as instantaneous non-lubrication. Based on the above performance advantages, silicon nitride ceramic bear...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B35/622C04B35/645
CPCC04B35/584C04B35/622C04B35/645C04B2235/3217C04B2235/3224C04B2235/3891C04B2235/445C04B2235/96
Inventor 曾宇平梁汉琴夏咏锋姚冬旭尹金伟
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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