阅读说明：本技术 一种Si3N4陶瓷材料及其制备方法 (Si3N4Ceramic material and preparation method thereof ) 是由 曾宇平 梁汉琴 左开慧 夏咏锋 姚冬旭 尹金伟 于 2021-02-03 设计创作，主要内容包括：本发明涉及一种Si-3N-4陶瓷材料及其制备方法,所述Si-3N-4陶瓷材料的原料组成包括：α-Si-3N-(4 )92～98 wt%、烧结助剂2～8 wt%,各组分质量百分比之和为100wt%；其中烧结助剂为Al-2O-3、Y-2O-3、Fe-2O-3和AlN。(The invention relates to Si 3 N 4 Ceramic material and method for preparing the same, said Si 3 N 4 The raw material composition of the ceramic material comprises: alpha-Si 3 N 4 92-98 wt% of sintering aid, 2-8 wt% of sintering aid, and the sum of the mass percentages of the components is 100 wt%; wherein the sintering aid is Al 2 O 3 、Y 2 O 3 、Fe 2 O 3 And AlN.)

1. Si₃N₄Ceramic material, characterized in that said Si₃N₄The raw material composition of the ceramic material comprises: alpha-Si₃N₄ 92-98 wt% of sintering aid, 2-8 wt% of sintering aid, and the sum of the mass percentages of the components is 100 wt%; wherein the sintering aid is Al₂O₃、Y₂O₃、Fe₂O₃And AlN;

preferably, alpha-Si₃N₄ 95-97 wt% of sintering aid, and 3-5 wt% of sintering aid, wherein the sum of the mass percentages of the components is 100 wt%.

2. Si according to claim 1₃N₄The ceramic material is characterized in that Fe is contained in the sintering aid₂O₃The content of (B) is 0.25-1.00 wt%.

3. Si according to claim 1 or 2₃N₄The ceramic material is characterized in that the AlN content in the sintering aid is 0.25-1.00 wt%; preferably, Al in the sintering aid₂O₃0.55-2.59 wt% of Y₂O₃The content of (A) is 1.27-3.67 wt%; more preferably, the Al₂O₃And Y₂O₃The molar ratio of (A) to (B) is 0.5 to 3.

4. Si according to any one of claims 1-3₃N₄Ceramic material, characterized in that said Si₃N₄The relative density of the ceramic material is 98.5-99.8%, and the bending resistance is strongThe temperature is 1102.3-1386.9 MPa; said Si₃N₄The Vickers hardness of the ceramic material is 17.1-18.6 GPa, and the fracture toughness is 10.2-13.8 MPa.m^1/2。

5. Si according to any one of claims 1 to 4₃N₄The preparation method of the ceramic material is characterized in that alpha-Si is used₃N₄The powder is used as a primary raw material and Al is used₂O₃Powder, Y₂O₃Powder of Fe₂O₃Powder and AlN powder are used as sintering aids, and are subjected to air pressure sintering and hot isostatic pressing post-treatment to obtain the Si₃N₄A ceramic material.

6. The method of claim 5, comprising:

(1) mixing the initial raw materials and the sintering aid to obtain mixed powder;

(2) pressing and molding the obtained mixed powder to obtain a biscuit;

(3) carrying out air pressure sintering and hot isostatic pressing post-treatment on the obtained biscuit to obtain the Si₃N₄A ceramic material.

7. The method of claim 6, wherein the mixing is performed by ball milling; the rotation speed of ball milling mixing is 200-400 rpm, and the ball milling time is 3-6 hours.

8. The preparation method according to claim 6 or 7, wherein the compression molding is dry-pressing pre-molding or/and cold isostatic pressing, preferably dry-pressing followed by cold isostatic pressing; more preferably, the pressure of the dry pressing is 5 to 20MPa, and the pressure of the cold isostatic pressing is 100 to 300 MPa.

9. The method of any one of claims 5-8, wherein the parameters of the gas pressure sintering comprise: the atmosphere is nitrogen atmosphere, and the air pressure is 0.5 MPa-2 MPa; the sintering temperature is 1650-1750 ℃, and the sintering time is 60-240 minutes.

10. The method of any one of claims 5-9, wherein the parameters of the post-hiping include: the temperature is 1550-1700 ℃, the heat preservation time is 0.5-2.5 hours, and the pressure is 100-200 MPa.

Technical Field

The invention relates to Si with low sintering temperature, low additive concentration and high strength₃N₄A ceramic material and a preparation method thereof, belonging to the preparation field of silicon nitride ceramics.

Background

The silicon nitride ceramic has the advantages of low density, good mechanical property, high temperature resistance, wear resistance, corrosion resistance, electric insulation, non-magnetic conductivity and the like, can be used as a bearing ball to completely cover the application field of precise and above-medium-speed all-steel bearing balls, and can be used in working environments which cannot be met by traditional metal balls, such as high speed, high and low temperature, large temperature difference, vacuum, insulation, non-magnetic conductivity, instant non-lubrication and the like. However, compared with imported balls, the friction and wear performance of the silicon nitride ceramic balls produced in China still has a large promotion space. On the one hand, according to the Hall-Petch effect, the smaller the grain size, the higher the hardness, and the better the wear resistance, but the grain size of the current domestic silicon nitride ball is larger, and thus the wear resistance needs to be further improved. On the other hand, since silicon nitride ceramics are decomposed at 1800 ℃ or higher, it is generally necessary to apply gas pressure using a gas pressure sintering furnace to avoid decomposition. However, the requirement for equipment is high, and the production cost is increased undoubtedly. Thus, to lower the sintering temperature, a larger amount of sintering aid is typically added to achieve low temperature densification. However, the mechanical property and wear resistance of the intergranular phase formed by the sintering aid are greatly different from those of silicon nitride, and the larger the addition amount of the sintering aid is, the more obvious the wear resistance of the silicon nitride ceramic is reduced.

Disclosure of Invention

In view of the above problems, it is an object of the present invention to provide a high-strength Si with a low sintering temperature and a low concentration of additives₃N₄Ceramics and a method for preparing the same. In particular, Al is intended₂O₃、Y₂O₃、Fe₂O₃And AlN as sintering aid, and preparing Si with high strength by combining air pressure sintering with hot isostatic pressing post-treatment₃N₄A ceramic material.

In one aspect, the present invention provides Si₃N₄Ceramic material of said Si₃N₄The raw material composition of the ceramic material comprises: alpha-Si₃N₄92-98 wt% of sintering aid 2 &8 wt%, wherein the sum of the mass percentages of the components is 100 wt%; wherein the sintering aid is Al₂O₃、Y₂O₃、Fe₂O₃And AlN. Preferably, said Si₃N₄The raw material composition of the ceramic material comprises: alpha-Si₃N₄95-97 wt% of sintering aid, and 3-5 wt% of sintering aid, wherein the sum of the mass percentages of the components is 100 wt%.

Preferably, Fe is contained in the sintering aid₂O₃The content of (B) is 0.25-1.00 wt%.

Preferably, the AlN content in the sintering aid is 0.25-1.00 wt%; preferably, Al in the sintering aid₂O₃0.55-2.59 wt% of Y₂O₃The content of (B) is 1.27 to 3.67 wt%.

Further, preferably, the Al is₂O₃And Y₂O₃The molar ratio of (A) to (B) is 0.5 to 3.

Preferably, said Si is₃N₄The relative density of the ceramic material is 98.5-99.8%, and the bending strength is 1102.3-1386.9 MPa.

Preferably, said Si is₃N₄The Vickers hardness of the ceramic material is 17.1-18.6 GPa, and the fracture toughness is 10.2-13.8 MPa.m^1/2。

On the other hand, the invention provides the Si₃N₄Method for producing ceramic material from alpha-Si₃N₄The powder is used as a primary raw material and Al is used₂O₃Powder, Y₂O₃Powder of Fe₂O₃Powder and AlN powder are used as sintering aids, and are subjected to air pressure sintering and hot isostatic pressing post-treatment to obtain the Si₃N₄A ceramic material.

Preferably, said Si is₃N₄The preparation method of the ceramic material comprises the following steps:

(1) mixing the initial raw materials and the sintering aid to obtain mixed powder;

(2) pressing and molding the obtained mixed powder to obtain a biscuit;

(3) carrying out air pressure sintering and hot isostatic pressing post-treatment on the obtained biscuitTo obtain said Si₃N₄A ceramic material.

Preferably, the mixing method is ball milling mixing; the rotation speed of ball milling mixing is 200-400 rpm, and the ball milling time is 3-6 hours.

Preferably, the compression molding mode is dry-pressing preforming or/and cold isostatic pressing, and preferably, the dry-pressing molding is performed firstly and then the cold isostatic pressing is performed; more preferably, the pressure of the dry pressing is 5 to 20MPa, and the pressure of the cold isostatic pressing is 100 to 300 MPa.

Preferably, the parameters of the gas pressure sintering include: the atmosphere is nitrogen atmosphere, and the air pressure is 0.5 MPa-2 MPa; the sintering temperature is 1650-1750 ℃, and the sintering time is 60-240 minutes.

Preferably, the parameters of the post-hiping treatment include: the temperature is 1550-1700 ℃, the heat preservation time is 0.5-2.5 hours, and the pressure is 100-200 MPa.

Has the advantages that:

in the present invention, by adding Fe₂O₃Using Fe₂O₃With SiO₂Reaction to form FeSi₂As beta-Si₃N₄Nucleation sites of grains promoting beta-Si₃N₄Form and alpha-beta Si₃N₄Phase transformation to form a microstructure with interlocked crystal grains, wherein the size of the crystal grains is 0.5 to 3 mu m. At the same time, AlN and Al₂O₃、Si₃N₄A Sialon phase can be formed, which has a specific Si content₃N₄Higher hardness, the presence of which contributes to Si₃N₄The hardness is improved, and Si can be fully eliminated by hot isostatic pressing post-treatment₃N₄Residual pores in the ceramic further increase Si₃N₄Strength of the ceramic, and obtaining Si with excellent comprehensive performance₃N₄A ceramic.

Drawings

FIG. 1 shows Si prepared in example 1₃N₄A topography of the polished surface of the ceramic;

FIG. 2 shows Si prepared in example 4₃N₄A topography of the polished surface of the ceramic;

FIG. 3 shows Si prepared in example 5₃N₄Topography of the polished surface of the ceramic.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

In the present disclosure, with α -Si₃N₄As a main phase, Al₂O₃、Y₂O₃、Fe₂O₃AlN is used as a sintering aid, low-temperature densification is realized under the conditions of low sintering temperature and low sintering aid concentration, and finally Si with high strength characteristic is obtained₃N₄A ceramic material.

The following is an exemplary illustration of the low sintering temperature, low promoter concentration, high strength Si provided by the present invention₃N₄A method for preparing the ceramic.

With alpha-Si₃N₄The powder is used as the initial raw material, Al₂O₃Powder, Y₂O₃Powder of Fe₂O₃The powder and the AlN powder are used as sintering aids. The total content of the sintering aid can be 2-8 wt% (preferably 3-5 wt%) based on 100% of the total mass of the initial raw materials and the sintering aid, and the balance is the initial raw materials.

In an alternative embodiment, the sintering aid comprises Fe₂O₃The content of (B) can be 0.25 to 1.00 wt%. In one aspect, Fe₂O₃Can be reacted with Al₂O₃And Y₂O₃Eutectic liquid phase is formed, and the sintering temperature is reduced. On the other hand, Fe₂O₃Can be used as beta-Si₃N₄Nucleation sites of grains promoting beta-Si₃N₄And (4) forming a nucleus. If it is Fe₂O₃The content of (a) is excessive, and the wear resistance of the silicon nitride ceramic is reduced.

In an optional embodiment, the AlN content in the sintering aid may be 0.25 to 1.00 wt%. Wherein AlN may be combined with Al₂O₃And Si₃N₄And the like to form Sialon solid solution, thereby further improving the hardness and toughness of the silicon nitride ceramic.

In an alternative embodiment, Al is present in the sintering aid₂O₃The content of (B) may be 0.55 to 2.59 wt%, Y₂O₃The content of (B) may be 1.27 to 3.67 wt%. Wherein, Al₂O₃And Y₂O₃The molar ratio of (a) to (b) may be 0.5 to 3, in order to form a low-melting liquid phase.

Mixing the initial raw materials and the sintering aid to obtain mixed powder. Wherein, the mixing mode can be grinding or/and ball milling mixing. For example, with Si₃N₄The ball is a ball milling ball, organic solvents such as ethanol and the like are used as grinding media for ball milling, and then the mixed powder is prepared by drying, grinding and sieving. Wherein, the rotation speed of ball milling can be 200-400 rpm, and the ball milling time can be 3-6 hours. The sieving mesh of the powder can be 100-400 meshes.

And performing dry pressing preforming or/and cold isostatic pressing on the mixed powder to obtain a formed biscuit. Wherein, the dry-pressing preforming pressure can be 5MPa to 20 MPa. The cold isostatic pressure can be 100-300 MPa.

The biscuit is placed in a BN crucible for air pressure sintering to complete Si₃N₄The primary densification of the ceramic is carried out, and Si is obtained after furnace cooling₃N₄Ceramic samples. Wherein, the atmosphere of the air pressure sintering can be nitrogen atmosphere, the temperature can be 1650-1750 ℃, the heat preservation time can be 60-240 min, and the air pressure can be 0.5-2 MPa.

Si after gas pressure sintering₃N₄And the ceramic sample is subjected to hot isostatic pressing post-treatment to promote complete densification of the silicon nitride ceramic, so that the high-strength and high-wear-resistance silicon nitride ceramic material is obtained. Wherein the hot isostatic pressing post-treatment temperature can be 1550-1700 ℃, the heat preservation time can be 0.5-2.5 h, and the air pressure (Ar or N)₂) Can be 100 to 200 MPa.

In the invention, the relative density of the silicon nitride ceramic material tested by the Archimedes drainage method can be 98.5-99.8%. The bending strength of the silicon nitride ceramic material tested by the universal testing machine can be 1102.3-1386.9 MPa. The Vickers hardness of the silicon nitride ceramic material tested by a Vickers hardness tester can be 17.1-18.6 GPa. Measurement by adopting single-side open beam methodThe fracture toughness of the silicon nitride ceramic material can be 10.2-13.8 MPa.m^1/2。

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.

Example 1

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95g Si₃N₄，1.73g Al₂O₃，1.27g Y₂O₃，1.00g Fe₂O₃And 1.00g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 3 hours at the rotating speed of 400 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry with a 400-mesh sieve, performing dry pressing preforming under the pressure of 20MPa, and performing cold isostatic pressing under the pressure of 300 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1750 ℃ and 2MPa for 240 minutes as protective gas, and then performing hot isostatic pressing treatment at 1700 ℃ for 2.5 hours under the air pressure of 200MPa to obtain the product with the relative density of 99.4%, the bending strength of 1305.7 +/-15.2 MPa, and the fracture toughness of 12.8 +/-0.11 MPam^1/2Si with Vickers hardness of 17.6 +/-0.04 GPa₃N₄A ceramic. For Si obtained in example 1₃N₄As a result of observing the polished surface of the ceramic, as shown in FIG. 1, the sample has a high density and a small grain size of about 1 to 2 μm.

Example 2

Si₃N₄Ceramic material and its useThe preparation method comprises the following steps:

s1 weighing 95g Si₃N₄，0.6g Al₂O₃，2.65g Y₂O₃，0.75g Fe₂O₃And 1.00g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 3 hours at the rotating speed of 400 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry with a 400-mesh sieve, performing dry pressing preforming under the pressure of 20MPa, and performing cold isostatic pressing under the pressure of 300 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1750 deg.C under 2MPa for 240min as protective gas, and hot isostatic pressing at 1700 deg.C for 1h under 200MPa to obtain the final product with relative density of 99.3%, bending strength of 1302.8 + -21.8 MPa, and fracture toughness of 12.5 + -0.19 MPa.m^1/2Si with Vickers hardness of 17.5 +/-0.15 GPa₃N₄A ceramic.

Example 3

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95g Si₃N₄，2.01g Al₂O₃，1.49g Y₂O₃，0.75g Fe₂O₃And 0.75g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 3 hours at the rotating speed of 400 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry with a 400-mesh sieve, performing dry pressing preforming under the pressure of 20MPa, and performing cold isostatic pressing under the pressure of 300 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1750 deg.C and 2MPa for 240min as shielding gas, hot isostatic pressing at 1650 deg.C for 0.5h under 150MPa to obtain the final product with relative density of 99.6%, bending strength of 1255.9 + -41.9 MPa, and fracture toughness of 12.3 + -0.17 MPa.m^1/2Vickers hardness of 17.9 +/-0.13Si of GPa₃N₄A ceramic.

Example 4

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95g Si₃N₄，1.47g Al₂O₃，2.03g Y₂O₃，1.00g Fe₂O₃And 0.50g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 3 hours at the rotating speed of 400 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry with a 400-mesh sieve, performing dry pressing preforming under the pressure of 20MPa, and performing cold isostatic pressing under the pressure of 300 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1700 ℃ under the pressure of 2MPa for 240 minutes as protective gas, and then carrying out hot isostatic pressing treatment at 1600 ℃ for 2 hours under the pressure of 150MPa to obtain the product with the relative density of 99.2%, the bending strength of 1223.2 +/-36.5 MPa, and the fracture toughness of 12.4 +/-0.08 MPam^1/2Si with Vickers hardness of 17.8 +/-0.28 GPa₃N₄A ceramic. For Si obtained in example 6₃N₄As shown in FIG. 2, the density of the sample is high, the grain size is small, about 1-2 μm, and the brightness is Fe-containing liquid phase.

Example 5

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95g Si₃N₄，2.16g Al₂O₃，1.59g Y₂O₃，0.50g Fe₂O₃And 0.75g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 4 hours at the rotating speed of 300 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry by a 200-mesh sieve, performing dry pressing preforming under the pressure of 10MPa, and performing cold isostatic pressing under the pressure of 200 MPa;

s4 step S3Putting the obtained ceramic biscuit into a BN mould, putting the ceramic biscuit into a pneumatic sintering furnace, and filling N into the furnace₂Sintering at 1650 deg.C under 1MPa for 120 min as shielding gas, hot isostatic pressing at 1650 deg.C for 1h at 100MPa to obtain the final product with relative density of 99.1%, bending strength of 1156.2 + -35.7 MPa, and fracture toughness of 11.9 + -0.27 MPam^1/2Si with Vickers hardness of 17.2 +/-0.16 GPa₃N₄A ceramic. Si obtained in example 5₃N₄As a result of observing the polished surface of the ceramic, as shown in FIG. 3, the sample has a high density, a small grain size of about 1-2 μm, and a bright Fe-containing liquid phase.

Example 6

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95g Si₃N₄，0.69g Al₂O₃，3.06g Y₂O₃，1.00g Fe₂O₃And 0.25g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 3 hours at the rotating speed of 400 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry with a 400-mesh sieve, performing dry pressing preforming under the pressure of 20MPa, and performing cold isostatic pressing under the pressure of 300 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1650 deg.C and 2MPa for 240min as shielding gas, hot isostatic pressing at 1550 deg.C for 1.5h under 100MPa to obtain the final product with relative density of 98.5%, bending strength of 1120.6 + -18.3 MPa, and fracture toughness of 10.44 + -0.24 MPa.m^1/2Si with Vickers hardness of 17.24 +/-0.14 GPa₃N₄A ceramic.

Example 7

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95g Si₃N₄，2.30g Al₂O₃，1.70g Y₂O₃，0.50g Fe₂O₃And 0.50g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 4 hours at the rotating speed of 300 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry by a 200-mesh sieve, performing dry pressing preforming under the pressure of 10MPa, and performing cold isostatic pressing under the pressure of 200 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1750 deg.C under 1MPa for 120 min as protective gas, and hot isostatic pressing at 1600 deg.C for 0.5h under 200MPa to obtain the final product with relative density of 99.8%, bending strength of 1349 + -37.9 MPa, and fracture toughness of 13.52 + -0.28 MPa.m^1/2Si with Vickers hardness of 18.46 +/-0.14 GPa₃N₄A ceramic.

Example 8

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95g Si₃N₄，1.68g Al₂O₃，2.32g Y₂O₃，0.75g Fe₂O₃And 0.25g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 4 hours at the rotating speed of 300 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry by a 200-mesh sieve, performing dry pressing preforming under the pressure of 10MPa, and performing cold isostatic pressing under the pressure of 200 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1750 deg.C under 1MPa for 120 min as shielding gas, hot isostatic pressing at 1550 deg.C for 2h at 200MPa to obtain the final product with relative density of 99.5%, bending strength of 1353.8 + -15.5 MPa, and fracture toughness of 13.5 + -0.14 MPa.m^1/2Si with Vickers hardness of 18.2 +/-0.02 GPa₃N₄A ceramic.

Example 9

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95g Si₃N₄，0.78g Al₂O₃，3.47g Y₂O₃，0.25g Fe₂O₃And 0.50g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 6 hours at the rotating speed of 200 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry by a 100-mesh sieve, performing dry pressing preforming under the pressure of 5MPa, and performing cold isostatic pressing under the pressure of 100 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1700 ℃ and 0.5MPa for 60 minutes as protective gas, and then performing hot isostatic pressing treatment at 1600 ℃ for 1 hour under the air pressure of 150MPa to obtain the alloy with the relative density of 99.4%, the bending strength of 1288.5 +/-52.6 MPa, the fracture toughness of 12.2 +/-0.31 MPa.m^1/2Si with Vickers hardness of 17.5 +/-0.25 GPa₃N₄A ceramic.

Example 10

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95g Si₃N₄，2.59g Al₂O₃，1.91g Y₂O₃，0.25g Fe₂O₃And 0.25g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 6 hours at the rotating speed of 200 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry by a 100-mesh sieve, performing dry pressing preforming under the pressure of 5MPa, and performing cold isostatic pressing under the pressure of 100 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1650 deg.C and 0.5MPa for 60 min as shielding gas, hot isostatic pressing at 1550 deg.C for 0.5h under 100MPa to obtain the final product with relative density of 98.6%, bending strength of 1108.6 + -55.8 MPa, and fracture toughness of 10.7 + -0.33 MPa-m^1/2Si with Vickers hardness of 17.2 +/-0.35 GPa₃N₄Ceramic material。

Comparative example 1

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95g Si₃N₄，2.30g Al₂O₃，1.70g Y₂O₃，0.50g Fe₂O₃And 0.50g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 4 hours at the rotating speed of 300 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry by a 200-mesh sieve, performing dry pressing preforming under the pressure of 10MPa, and performing cold isostatic pressing under the pressure of 200 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1750 deg.C under 1MPa for 120 min as shielding gas, hot isostatic pressing at 1600 deg.C for 0.5h under 200MPa to obtain the final product with relative density of 99.7%, bending strength of 1363.2 + -21.6 MPa, and fracture toughness of 13.6 + -0.17 MPa.m^1/2Si with Vickers hardness of 17.5 +/-0.09 GPa₃N₄A ceramic.

Comparative example 2

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95.5g Si₃N₄，2.30g Al₂O₃，1.70g Y₂O₃And 0.50g Fe₂O₃A total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 4 hours at the rotating speed of 300 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry by a 200-mesh sieve, performing dry pressing preforming under the pressure of 10MPa, and performing cold isostatic pressing under the pressure of 200 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1750 deg.C under 1MPa for 120 min as shielding gas, hot isostatic pressing at 1600 deg.C for 0.5h under 200MPa to obtain the final productThe density is 99.6 percent, the bending strength is 1314.3 +/-59.6 MPa, and the fracture toughness is 13.2 +/-0.22 MPa.m^1/2Si with Vickers hardness of 17.8 +/-0.16 GPa₃N₄A ceramic.

Comparative example 3

Si₃N₄The ceramic material and the preparation method thereof comprise the following steps:

s1 weighing 95.5g Si₃N₄，2.30g Al₂O₃，1.70g Y₂O₃And 0.50g AlN for a total of 100 g;

s2, preparing the mixed powder obtained in the step S1 into slurry with certain solid content, and carrying out planetary ball milling for 4 hours at the rotating speed of 300 rpm;

s3, drying and grinding the slurry obtained in the step S2, sieving the ground slurry by a 200-mesh sieve, performing dry pressing preforming under the pressure of 10MPa, and performing cold isostatic pressing under the pressure of 200 MPa;

s4, placing the ceramic biscuit obtained in the step S3 into a BN mould, placing the BN mould into an air pressure sintering furnace, and filling N into the air pressure sintering furnace₂Sintering at 1750 deg.C under 1MPa for 120 min as shielding gas, hot isostatic pressing at 1600 deg.C for 0.5h under 200MPa to obtain the final product with relative density of 99.2%, bending strength of 1293.2 + -26.6 MPa, and fracture toughness of 12.9 + -0.19 MPa.m^1/2Si with Vickers hardness of 17.5 +/-0.18 GPa₃N₄A ceramic.

Comparative example 4

Si in this comparative example 4₃N₄The ceramic material was prepared according to example 7, with the following differences: weighing 96g of Si₃N₄，2.30g Al₂O₃，1.70g Y₂O₃The total amount is 100 g. Obtained Si₃N₄The ceramic relative density is 98.2 percent, the bending strength is 1087.2 +/-45.7 MPa, and the fracture toughness is 9.9 +/-0.23 MPa.m^1/2The Vickers hardness is 16.8 +/-0.22 GPa.

Comparative example 5

Si in this comparative example 5₃N₄The ceramic material was prepared according to example 7, with the following differences: 94.25g of Si are weighed out₃N₄，2.30g Al₂O₃，1.70g Y₂O₃，1.25g Fe₂O₃And 0.50g AlN totaled 100 g. Obtained Si₃N₄The ceramic relative density is 98.9 percent, the bending strength is 1186.9 +/-31.2 MPa, and the fracture toughness is 10.9 +/-0.25 MPa.m^1/2The Vickers hardness is 17.2 +/-0.16 GPa.

Comparative example 6

Si in this comparative example 6₃N₄The ceramic material was prepared according to example 7, with the following differences: 94.25g of Si are weighed out₃N₄，2.30g Al₂O₃，1.70g Y₂O₃，0.50Fe₂O₃And 1.25g AlN totaled 100 g. Obtained Si₃N₄The ceramic relative density is 98.3 percent, the bending strength is 1077.4 +/-19.5 MPa, and the fracture toughness is 11.3 +/-0.34 MPa.m^1/2The Vickers hardness is 17.2 +/-0.28 GPa.

Comparative example 7

Si in this comparative example 7₃N₄The ceramic material was prepared according to example 7, with the following differences: 91g of Si are weighed₃N₄，4.6g Al₂O₃，3.4g Y₂O₃，0.50Fe₂O₃And 0.5g AlN for a total of 100 g. Obtained Si₃N₄The ceramic has a relative density of 99.1%, a bending strength of 1277.4 + -25.8 MPa, and a fracture toughness of 12.8 + -0.27 MPa-m^1/2The Vickers hardness is 16.7 +/-0.11 GPa.

Table 1 shows Si prepared according to the invention₃N₄The raw material composition and performance parameters of the ceramic material are as follows:

as can be seen from the above embodiment, the invention is realized by adding Si₃N₄Adding Al to the matrix₂O₃、Y₂O₃、Fe₂O₃And AlN as sintering assistant, and adopting air pressure sintering and hot isostatic pressing post-treatmentIn this manner, Si having high strength, high toughness and high hardness can be obtained₃N₄A ceramic.

Finally, it is necessary to mention that: the above embodiments are only used for further detailed description of the technical solutions of the present invention, and should not be understood as limiting the scope of the present invention, and the insubstantial modifications and adaptations made by those skilled in the art according to the above descriptions of the present invention are within the scope of the present invention.