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Preparation method of silicon nitride-based multiphase conductive ceramic

A technology based on conductive ceramics and silicon nitride, which is applied in the field of conductive ceramics, can solve the problems of hindering the sintering densification of silicon nitride, the decrease of mechanical properties such as hardness and strength of silicon nitride ceramics, and achieve the purpose of inhibiting the growth of grains and mechanical properties. Effects of improving performance and suppressing grain boundary migration

Active Publication Date: 2021-05-28
SINOMA ADVANCED NITRIDE CERAMICS CO LTD
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Problems solved by technology

However, the addition of the conductive phase will hinder the sintering and densification of silicon nitride, so that when preparing multi-phase conductive ceramics, it is necessary to use hot-press sintering or high-temperature (≥1800°C) pressure sintering to achieve densification, and the above-mentioned sintering method will be Lead to the decline of mechanical properties such as hardness and strength of silicon nitride ceramics

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  • Preparation method of silicon nitride-based multiphase conductive ceramic
  • Preparation method of silicon nitride-based multiphase conductive ceramic
  • Preparation method of silicon nitride-based multiphase conductive ceramic

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preparation example Construction

[0023] The invention provides a method for preparing silicon nitride-based multiphase conductive ceramics, comprising the following steps:

[0024] (1) Mixing silicon nitride, a conductive phase and a sintering aid and then molding to obtain a green body; the sintering aid includes rare earth oxides and metal oxides, and the metal oxides include aluminum oxide or magnesium oxide;

[0025] (2) Sequentially performing high-temperature microwave sintering and low-temperature microwave sintering on the green body obtained in the step (1) to obtain silicon nitride-based multiphase conductive ceramics.

[0026] In the invention, silicon nitride, conductive phase and sintering auxiliary agent are mixed and then molded to obtain a green body.

[0027] In the present invention, the mass content of silicon nitride in the green body is preferably 40-60%, more preferably 45-55%. In the present invention, the β-Si in the silicon nitride 3 N 4 The mass content of is preferably ≥ 85%, mor...

Embodiment 1

[0048] raw material:

[0049] Silicon nitride (β-Si 3 N 4 The mass content of ≥95%, the average particle size D50 is 0.5μm): 53%,

[0050] Titanium nitride (purity ≥ 99%, average particle size D50 is 0.1μm): 35%,

[0051] Alumina (purity ≥ 99%, average particle size D50 is 0.5μm): 3%,

[0052] Yttrium oxide (purity ≥ 99%, average particle size D50 is 0.2μm): 6%,

[0053] Silicon carbide (purity ≥ 98.5%, average particle size D50 of 0.5 μm): 3%.

[0054] After the above raw materials are mixed evenly, dry pressing is performed first, the size of the obtained product is 45×45×8mm, the pressure of dry pressing is 20MPa, and then cold isostatic pressing is performed, and the pressure of cold isostatic pressing is 300MPa, and the obtained body. Put the above green body into the furnace cavity of the microwave sintering furnace, evacuate until the vacuum degree in the furnace is less than 100Pa, and then pass nitrogen gas to make the pressure in the furnace reach 0.1MPa. After...

Embodiment 2

[0056] raw material:

[0057] Silicon nitride (β-Si 3 N 4 The mass content of ≥95%, the average particle size D50 is 0.5μm): 50%,

[0058] Titanium nitride (purity ≥ 99%, average particle size D50 is 0.1μm): 40%,

[0059] Alumina (purity ≥ 99%, average particle size D50 is 0.5μm): 3%,

[0060] Yttrium oxide (purity ≥ 99%, average particle size D50 is 0.2μm): 5%,

[0061] Silicon carbide (purity ≥ 98.5%, average particle size D50 of 0.5 μm): 2%.

[0062] After the above raw materials are mixed evenly, dry pressing is performed first, the size of the obtained product is 45×45×8mm, the pressure of dry pressing is 20MPa, and then cold isostatic pressing is performed, and the pressure of cold isostatic pressing is 300MPa, and the obtained body. Put the above green body into the furnace cavity of the microwave sintering furnace, evacuate until the vacuum degree in the furnace is less than 100Pa, and then pass nitrogen gas to make the pressure in the furnace reach 0.1MPa. After...

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Abstract

The invention provides a preparation method of silicon nitride-based multiphase conductive ceramic. According to the invention, silicon nitride is taken as a matrix, a conductive phase and a sintering aid are added, and a two-step microwave sintering method is adopted, so that the prepared silicon nitride-based multiphase conductive ceramic is fine and uniform in grain and high in density, and the mechanical properties such as strength and hardness are also remarkably improved. A two-step microwave sintering method is adopted, grain boundary migration can be inhibited, and densification is achieved through grain boundary diffusion. Therefore, the method not only can inhibit the growth of crystal grains in the later stage of sintering, but also does not affect the densification. The result of the embodiment shows that the relative density of the silicon nitride-based multiphase conductive ceramic provided by the invention is greater than 99%, the Vickers hardness is greater than 15 GPa, the fracture toughness is greater than 6 MPa.m<1 / 2>, the bending strength is greater than 900 MPa, and the resistivity is less than 1 [omega].cm.

Description

technical field [0001] The invention relates to the technical field of conductive ceramics, in particular to a method for preparing a silicon nitride-based composite phase conductive ceramic. Background technique [0002] Silicon nitride ceramics have excellent comprehensive mechanical properties, especially the advantages of high strength, high hardness, high toughness and good wear resistance, and have high chemical stability and thermal shock resistance. They are ideal engineering ceramics Materials are widely used in the fields of machinery, chemical industry, aerospace and national defense and military industry. However, due to the electrical insulation of silicon nitride ceramics, traditional diamond tools can only be used for machining. The processing efficiency is low, the cost is high, and it cannot be processed into parts with complex shapes, which severely limits the application of silicon nitride ceramics. [0003] By introducing titanium-based compounds (TiN, T...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B35/64
CPCC04B35/584C04B35/64C04B2235/3225C04B2235/3227C04B2235/3229C04B2235/3206C04B2235/3217C04B2235/667C04B2235/3886C04B2235/3843C04B2235/3856C04B2235/3813C04B2235/3839C04B2235/3891C04B2235/3826C04B2235/3244C04B2235/6562C04B2235/6565C04B2235/77C04B2235/96
Inventor 张伟儒张晶孙峰董廷霞李泽坤李洪浩徐金梦荆赫吕沛远
Owner SINOMA ADVANCED NITRIDE CERAMICS CO LTD
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