Method for preparing Si3N4 gradient material through self-diffusion

A gradient material and self-diffusion technology, which is applied in the field of non-oxide ceramic matrix composite materials, can solve the problems of insufficient bonding force between the matrix and the conductive layer, detachment of the surface layer from the core, and weak bonding force.

Inactive Publication Date: 2018-04-24
GUANGDONG UNIV OF TECH
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Problems solved by technology

[0002] Si 3 N 4 As a structural material, ceramic materials have excellent mechanical properties, such as high hardness, high strength, wear resistance, high temperature resistance, etc., and can be widely used in bearings, high-speed cutting tools, armor, etc., but in extremely high temperature and high-speed cutting It is still easy to wear under harsh conditions such as Si 3 N 4 Ceramics can usually be used to prepare gradient materials, or to process them with PVD or CVD coatings
[0003] At present, the preparation of gradient materials is mainly through sintering materials with different formulas or different raw materials to achieve different propertie...

Method used

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  • Method for preparing Si3N4 gradient material through self-diffusion

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Effect test

Embodiment 1

[0028] A preparation of Si by self-diffusion 3 N 4 The specific method of gradient material is as follows:

[0029] (1) with Si 3 N 4 and ZrO 2 Powder as raw material, with MgO and Y 2 o 3 As a sintering aid, according to Si 3 N 4 : ZrO 2 : MgO-Re 2 o 3 The mass fraction ratio is 70%:20%:10%, the MgO-Re 2 o 3 MgO in: Re 2 o 3 The mass fraction ratio is 55%: 45%; with ethanol as solvent and Si 3 N 4 The ball is the ball milling medium, mixed on a roller ball mill for 24 hours, after mixing and drying, a uniformly mixed Si-ZrO 2 -MgO-Y 2 o 3 Mix powder.

[0030] (2) Si-ZrO 2 -MgO-Y 2 o 3 The mixed powder is put into a mold for cold isostatic pressing molding, the cold isostatic pressing molding pressure is 200MPa, and the holding time is 5min.

[0031] (3) Si-ZrO 2 -MgO-Y 2O 3 The green body is embedded in Si 3 N 4 The powder is put into a boron nitride crucible, the temperature is raised to 1400°C for 2 hours at a heating rate of 20°C / min, and then t...

Embodiment 2

[0034] According to Si 3 N 4 : ZrO 2 : MgO-Re 2 O 3 The mass fraction ratio is 50%: 40%: 10% for batching, in which MgO: Yb 2 O 3 The mass fraction ratio is 60%: 40%, and Si is prepared according to the method of Example 1 3 N 4 Ceramics, in which the temperature is first heated to 1375 °C for 24 hours, then heated to 1900 °C for 12 hours, and sintered at a pressure of 10 MPa, and the sintering atmosphere is nitrogen. The relative density of the prepared ceramic material is 99%, the hardness of the material is 25GPa, and the fracture toughness is 14MPa m 1 / 2 , the flexural strength is 1500Mpa, and the gradient layer thickness is 100μm.

Embodiment 3

[0036] According to Si 3 N 4 : TiO 2 : MgO-Gd 2 O 3 The mass fraction ratio is 72%: 20%: 8% for batching, in which MgO: Gd 2 O 3 The mass fraction ratio is 60%: 40%, and Si is prepared according to the method of Example 1 3 N 4 Ceramics, in which the temperature is first heated to 1375 °C for 4 hours, and then heated to 1900 °C for 4 hours, and sintered at a pressure of 10 MPa, and the sintering atmosphere is nitrogen. The relative density of the prepared ceramic material is 99%, the hardness of the material is 20GPa, and the fracture toughness is 14MPa m 1 / 2 , the flexural strength is 1200Mpa, and the gradient layer thickness is 80μm.

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Abstract

The invention discloses a method for preparing a Si3N4 gradient material through self-diffusion. The method comprises steps as follows: Si3N4 and MO2 powder are taken as raw materials, wherein M is Ti, Zr or Hf, MgO-Re2O3 is taken as a sintering aid, the components are mixed and dried, and mixed powder is obtained; after the mixed powder is subjected to isostatic cool pressing, a sample is embedded in the powder, the mixture is put in a sintering furnace, and the Si3N4 gradient material is obtained finally. A gradient MN layer is formed on the surface of the Si3N4 material prepared with the method, and MN as a high-hardness and wear-resistant conductive phase can allow direct coating treatment on the surface of Si3N4 ceramic while improving surface hardness and wear resistance of the Si3N4ceramic; relative density is higher than 95%, surface hardness is 18-25 GPa, fracture toughness is 10-14 MPa.m<1/2>, bending strength is 1000-1500 Mpa, and gradient layer thickness is 10-200 mu m.

Description

technical field [0001] The invention relates to the technical field of non-oxide ceramic matrix composite materials, in particular to a method for preparing Si by self-diffusion 3 N 4 Gradient material method. Background technique [0002] Si 3 N 4 As a structural material, ceramic materials have excellent mechanical properties, such as high hardness, high strength, wear resistance, high temperature resistance, etc., and can be widely used in bearings, high-speed cutting tools, armor, etc., but in extremely high temperature and high-speed cutting It is still easy to wear under harsh conditions such as Si 3 N 4 Ceramics can usually be prepared as gradient materials, or they can be treated with PVD or CVD coating. [0003] At present, the preparation of gradient materials is mainly through sintering materials with different formulas or different raw materials to achieve different properties of surface layer and hardness. However, due to the difference in composition and ...

Claims

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Application Information

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IPC IPC(8): C04B35/584C04B35/622
CPCC04B35/584C04B35/622C04B2235/3224C04B2235/3244C04B2235/658C04B2235/6587C04B2235/75C04B2235/96
Inventor 郭伟明吴利翔牛文彬林华泰
Owner GUANGDONG UNIV OF TECH
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