CN112851360A

CN112851360A - ZrN-based ultrahigh-temperature ceramic and hot-pressing reaction sintering preparation method thereof

Info

Publication number: CN112851360A
Application number: CN202110127210.7A
Authority: CN
Inventors: 陆有军; 刘洋; 袁振侠; 李彦瑞; 刘乡
Original assignee: North Minzu University
Current assignee: North Minzu University
Priority date: 2021-01-29
Filing date: 2021-01-29
Publication date: 2021-05-28

Abstract

The invention provides a ZrN-based ultrahigh-temperature ceramic, the main phase of which comprises ZrN and La_4.67Si₃O₁₃Wherein, La_4.67Si₃O₁₃The ZrN crystal grains are uniformly and continuously distributed among the ZrN crystal grain gaps, and the size of the ZrN crystal grains is 20-50 mu m; the ceramic has a bulk density of 87-98%, a hardness of 10.0-11.5GPa, a bending strength of 240-310MPa and a fracture toughness of 1.90-2.05MPa.m^1/2. Also provides a hot-pressing reaction of the ZrN-based ultrahigh-temperature ceramicA preparation method of the ceramic material by sintering comprises the following steps: weighing alpha-Si with the molar ratio of 3:9:7:3 (22-66)₃N₄、ZrO₂、La₂O₃Adding a proper amount of auxiliary agent into the Zr powder and the ZrN powder, performing ball milling treatment, drying, grinding, molding treatment and hot-pressing sintering treatment in sequence to obtain the ZrN-based ultrahigh-temperature ceramic.

Description

ZrN-based ultrahigh-temperature ceramic and hot-pressing reaction sintering preparation method thereof

Technical Field

The invention belongs to the field of inorganic ceramic materials, and particularly relates to a ZrN-based ultrahigh-temperature ceramic and a hot-pressing reaction sintering preparation method thereof.

Background

Ultra High Temperature Ceramics (UHTCs) refer to ceramic materials that provide mechanical stability and heat dissipation when operated in extreme environments (e.g., extreme heat flux, chemically reactive plasma, or harsh environments with extremely high oxygen content), and have stable physicochemical properties, such as high thermal and electrical conductivity, good thermal shock resistance, excellent corrosion resistance, and the like. UHTCs materials are mainly borides, carbides and nitrides of transition metals (Ti, Zr, Hf, Nb, Ta, etc.) and ceramic materials compounded with them, including zirconium diboride (ZrB)₂) Hafnium diboride (HfB)₂) Zirconium carbide (ZrC), hafnium carbide (HfC), zirconium nitride (ZrN), hafnium nitride (HfN), and the like. ZrN has high melting point, high hardness, high wear resistance and good corrosion resistance as an ultra-high temperature ceramic (UHTCs), and the sintering difficulty is very high due to the strong covalent bond, high melting point and low diffusion coefficient of ZrN, so that the preparation of the ultra-high temperature ZrN ceramic by in-situ reaction sintering is considered to be a low-consumption and economic preparation method.

Si₃N₄-ZrO₂The binary system can prepare ZrN ceramic through reaction sintering, but SiO and N are generated in the reaction sintering process₂、O₂And when the gas is generated, the burning loss rate is high, and the ceramic block with high density cannot be obtained. To reduce or eliminate volatile gases generated during reactive sintering, the applicant's research team has been working on Si₃N₄-ZrO₂Introduction of rare earth into binary systemMetallic oxide La₂O₃To solidify volatile gas SiO and promote Si₃N₄-ZrO₂Substitution reaction to form ZrN (see "Si₃N₄-ZrO₂-La₂O₃System reaction synthesis ZrN and phase diagram construction, Lianrui, Lujun, etc., inorganic material declaration No. 35, No. 7, page 823-826), by design Si₃N₄-ZrO₂-La₂O₃The ternary system can generate ZrN phase and various rare earth silicate phase composite ceramics by in-situ reaction sintering, the generation of the rare earth silicate phase effectively inhibits the generation of SiO gas, the sintering density of a reaction sintered ceramic block is improved, but according to Si₃N₄-ZrO₂-La₂O₃Conservation of elements in the ternary system reaction, ZrO in the reaction system₂Zr in the process of being nitrided to generate ZrN⁴⁺Is reduced to Zr³⁺With evolution of gas, when Si₃N₄:ZrO₂1:3 to form N₂When Si is present₃N₄:ZrO₂At 1:4, O is formed₂So that the oxygen partial pressure of the system is increased, and when the temperature reaches 800 ℃, ZrN starts to be oxidized by oxygen, so that the generation amount of ZrN is reduced. To further avoid gas to Si₃N₄-ZrO₂-La₂O₃The invention relates to the influence of ternary system reaction on the performance of ZrN-based complex phase ceramic preparation, redesigns a reaction sintering system, and combines a corresponding sintering mechanism to prepare the ZrN-based complex phase ceramic material with excellent comprehensive performance.

Disclosure of Invention

One of the purposes of the invention is to provide a ZrN based superhigh temperature ceramic with excellent comprehensive performance.

The other purpose of the invention is to provide a hot-pressing reaction sintering preparation method of ZrN-based ultrahigh-temperature ceramic, which avoids gas to Si by introducing a Zr simple substance and ZrN into a raw material system₃N₄-ZrO₂-La₂O₃The influence of the performance of the ZrN-based complex phase ceramic prepared by the ternary system reaction can regulate the appearance of silicate phase in the product, and the strength of the ceramic is further improved by properly adding ZrNChemical properties.

In order to achieve the purpose, the invention adopts the following technical scheme:

ZrN-based ultrahigh-temperature ceramic with ZrN and La as main phases_4.67Si₃O₁₃Wherein, La_4.67Si₃O₁₃The ZrN crystal grains are uniformly and continuously distributed among ZrN crystal grain gaps, and the size of the ZrN crystal grains is 20-50 μm (such as 25 μm, 30 μm, 35 μm, 40 μm, 45 μm and the like); the ZrN-based ultrahigh temperature ceramic has the volume density of 87-98 percent (such as 88 percent, 90 percent, 92 percent, 94 percent, 96 percent, 97 percent and the like), the hardness of 10.0-11.5GPa (such as 10.2GPa, 10.4GPa, 10.6GPa, 10.8GPa, 11.0GPa, 11.2GPa, 11.4GPa and the like), the bending strength of 240-310MPa (such as 250MPa, 260MPa, 270MPa, 280MPa, 290MPa, 300MPa and the like), and the fracture toughness of 1.90-2.05MPa.m^1/2(e.g., 1.92MPa. m)^1/2、1.94MPa.m^1/2、1.96MPa.m^1/2、1.98MPa.m^1/2、2.00MPa.m^1/2Etc.).

Preferably, the ZrN based ultra high temperature ceramic has a volume density of 95% -98% (such as 95.5%, 96%, 96.5%, 97%, 97.5%, etc.), a hardness of 10.5-11.2GPa (such as 10.6GPa, 10.8GPa, 11.0GPa, etc.), a bending strength of 275-302MPa (such as 280MPa, 285MPa, 290MPa, 295MPa, 300MPa, etc.), and a fracture toughness of 1.94-2.05MPa. m^1/2。

The ZrN-based ultrahigh-temperature ceramic can be prepared by mixing raw material components of alpha-Si₃N₄、ZrO₂、La₂O₃And the Zr powder and the ZrN powder are subjected to powder mixing, pressing and hot pressing sintering to obtain the Zr-N powder.

A hot-pressing reaction sintering preparation method of ZrN-based ultrahigh-temperature ceramic comprises the following steps:

the method comprises the following steps of: weighing appropriate amount of alpha-Si₃N₄、ZrO₂、La₂O₃Adding a proper amount of auxiliary agent into Zr powder and ZrN powder, performing ball milling treatment, and then performing drying treatment and grinding treatment to obtain mixture powder;

a molding treatment step: placing the mixture powder in a forming die, and applying pressure to perform forming treatment to obtain a forming blank;

the hot-pressing reaction sintering treatment step: carrying out hot-pressing sintering treatment on the formed blank to obtain the ZrN-based ultrahigh-temperature ceramic; wherein, in the raw material pretreatment step, the alpha-Si is₃N₄Expressed in m, said ZrO₂Is represented by n, and the La₂O₃The mol number of the Zr powder is expressed by x, the mol number of the Zr powder is expressed by y, the mol number of the ZrN powder is expressed by z, and the preferable mixture ratio of the raw materials is as follows: m: n: y: z: 3:9:7:3 (22-66) (e.g., 3:9:7:3:25, 3:9:7:3:30, 3:9:7:3:33, 3:9:7:3:38, 3:9:7:3:40, 3:9:7:3:44, 3:9:7:3:50, 3:9:7:3:55, 3:9:7:3:60, etc.).

In the above method for preparing ZrN-based ultra-high temperature ceramic by hot-press reaction sintering, as a preferred embodiment, in the step of pretreating the raw material, the α -Si is added₃N₄The purity of (2) is 99.9% or more and the particle size is 0.7 μm or less (for example, 0.6 μm, 0.5 μm, 0.4 μm, 0.3 μm, 0.2 μm, 0.1 μm, etc.); the ZrO₂The purity of the crystal is more than 99.9 percent, and the particle size is less than 100nm (such as 90nm, 80nm, 70nm, 50nm, 30nm and the like); the La₂O₃The purity of (2) is 99.9% or more and the particle size is 10 μm or less (for example, 8 μm, 6 μm, 5 μm, 3 μm, 2 μm, 1 μm, etc.); the Zr powder has the purity of more than 99.5 percent and the granularity of 200 meshes (namely, the Zr powder is sieved by a 200-mesh sieve, and is less than about 75 microns, such as 70 microns, 60 microns, 50 microns, 40 microns and the like); the ZrN powder has a purity of 99% and a particle size of 400 mesh (i.e., passing through a 400 mesh sieve, about 38 μm or less, such as 35 μm, 30 μm, 25 μm, 20 μm, 10 μm, etc.).

In the above method for preparing ZrN-based ultrahigh-temperature ceramic by hot-pressing reactive sintering, as a preferred embodiment, in the step of pretreating the raw material, the auxiliary agent is ethanol.

In the above preparation method of the ZrN-based ultrahigh temperature ceramic by hot-pressing reactive sintering, as a preferred embodiment, in the raw material pretreatment step, the time of the ball milling treatment is 30-180min (e.g., 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min, etc.), and the rotation speed of the ball mill is set to 500-.

In the above method for preparing ZrN-based ultrahigh-temperature ceramic by hot-press reaction sintering, as a preferred embodiment, in the step of pretreating the raw material, the temperature of the drying treatment is 90-110 ℃ (for example, 92 ℃, 95 ℃, 100 ℃, 105 ℃, 108 ℃ and the like), and the time is 3-12h (for example, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h and the like).

In the above method for producing a ZrN-based ultrahigh-temperature ceramic by hot-press reaction sintering, as a preferred embodiment, in the step of forming, the pressure is 2MPa to 5MPa (for example, 2.5MPa, 3MPa, 3.5MPa, 4MPa, 4.5MPa, etc.).

In the above method for preparing ZrN-based ultra-high temperature ceramic by hot-press reaction sintering, as a preferred embodiment, in the hot-press reaction sintering treatment step, the sintering temperature is 1550-; more preferably, in the hot-pressing reaction sintering treatment step, the temperature is uniformly raised to 1600 ℃ (sintering temperature) within 0-80min, the temperature is uniformly raised to 24KN (sintering pressure) within 0-80min, then the temperature is maintained at 1600 ℃ and 24KN for sintering for 60-80min, then heating is stopped, and the temperature is reduced to room temperature, so that the ZrN-based ultrahigh-temperature ceramic is prepared.

Performing phase analysis on the ceramic prepared by the hot-pressing reaction sintering preparation method of the ZrN-based ultrahigh-temperature ceramic, wherein the phase analysis is mainly performed by ZrN and La_4.67Si₃O₁₃Composition, microstructure, La_4.67Si₃O₁₃The ZrN crystal grains are uniformly and continuously distributed among the ZrN crystal grain gaps, and the size of the ZrN crystal grains is 20-50 mu m; according to the measurement, the volume density of the ZrN-based ultrahigh temperature ceramic is 87-98 percent, the hardness is 10-11.5GPa, the bending strength is 240-310MPa, and the fracture toughness is 1.90-2.05MPa.m^1/2In the meantime.

In the reaction system of the present invention, ZrO₂Zr in the process of being nitrided to generate ZrN⁴⁺Is reduced to Zr³⁺With evolution of gas, when Si₃N₄:ZrO₂1:3 to form N₂To avoid N₂Gas pair Si₃N₄-ZrO₂-La₂O₃The influence of ternary system reaction on the performance of preparing ZrN-based multiphase ceramic is characterized in that a metal Zr simple substance is introduced into the raw material system, the metal Zr has strong chemical affinity with oxidants such as nitrogen and oxygen, and can respectively form ZrN and ZrO at high temperature₂Maintaining the generation amount of ZrN and reducing the generation of silicate phase; meanwhile, ZrN is properly added into the raw material system, so that the ZrN content in the ceramic product can be stabilized, and the mechanical property of the ceramic product can be improved.

Compared with the prior art, the beneficial effects of the invention include but are not limited to:

1) the ZrN-based ultrahigh-temperature ceramic provided by the invention has main phases of ZrN and La_4.67Si₃O₁₃Composition, microstructure, La_4.67Si₃O₁₃The ZrN-based superhigh temperature ceramic is uniformly and continuously distributed among ZrN crystal grain gaps and presents a random shape, the size of the ZrN crystal grain is 20-50 mu m, the ZrN-based superhigh temperature ceramic has excellent comprehensive performance, the volume density can reach 95% -98%, the hardness can reach 10-11GPa, the bending strength can reach 248-^1/2The above;

2) the hot-pressing reaction sintering preparation method of the ZrN-based ultrahigh-temperature ceramic provided by the invention has the advantages that the elemental metal Zr is introduced into the raw material system to prevent gas from reacting on Si₃N₄-ZrO₂-La₂O₃The influence of the performance of the ZrN-based complex phase ceramic prepared by the ternary system reaction can regulate the appearance of silicate phase in the product, improve the comprehensive performance of the ZrN-based complex phase ceramic, and further improve the mechanical property of the ceramic product by properly adding ZrN in a raw material system.

Drawings

FIG. 1 is a hot press sintering schedule curve for examples 1-3 and comparative examples 1-2;

FIG. 2 is an XRD pattern of sintered samples of examples 1-3 and comparative example 1;

FIG. 3 is an SEM microtopography (scale bar 100 μm) of sintered samples of examples 1-3 and comparative example 1, wherein (a) is the microtopography of the sintered ceramic body of example 1, (b) is the microtopography of the sintered ceramic body of example 2, (c) is the microtopography of the sintered ceramic body of example 3, and (d) is the microtopography of the sintered ceramic body of comparative example 1;

FIG. 4 is a graph of bulk density and relative density of sintered samples from examples 1-3 and comparative examples 1-2;

FIG. 5 is a graph comparing hardness of sintered samples of examples 1-3 and comparative examples 1-2;

FIG. 6 is a graph comparing the bending strength of sintered samples of examples 1-3 and comparative examples 1-2;

FIG. 7 is a graph comparing fracture toughness of sintered samples of examples 1-3 and comparative examples 1-2.

Detailed Description

The following examples are given to facilitate a better understanding of the invention, but do not limit the invention.

The experimental procedures in the following examples are conventional unless otherwise specified.

The test materials used in the following examples were purchased from a conventional biochemical reagent store unless otherwise specified.

Example 1

1) Selecting alpha-Si₃N₄Powder with purity of 99.9% and granularity less than or equal to 0.7 micron; ZrO (ZrO)₂Powder: the purity is 99.9 percent, and the granularity is less than or equal to 100 nm; la₂O₃Powder: the purity is 99.9 percent, and the granularity is less than or equal to 10 mu m; zr powder: purity 99.5%, particle size 200 mesh (200 mesh powder); ZrN powder: the purity is 99 percent, and the granularity is 400 meshes (powder is sieved by a 400-mesh sieve); wherein alpha-Si₃N₄、ZrO₂、La₂O₃A raw material powder, designated as 3S9Z7L3Zr22ZN, was prepared with a molar ratio of Zr powder to ZrN of m: n: x: y ═ 3:9:7:3: 22;

2) weighing the raw material powder in the proportion, then using ethanol as a medium, putting the raw material powder into a ball milling tank, carrying out ball milling for 40min, setting the rotating speed of the ball milling tank to be 500r/min, drying the mixed raw material after ball milling, controlling the drying temperature to be within 90 ℃, setting the drying time to be 12 hours, and grinding the mixture after drying;

3) placing the ground mixture powder into a forming die, and applying pressure in a press machine for forming, wherein the pressure range is set to be 5 MPa;

4) and (2) sintering the pressed and formed blank in a hot-pressing sintering furnace, heating to 1600 ℃ at the speed of about 20 ℃/min within 0-80min, pressurizing to 24KN at the speed of about 3KN/10min within 0-80min, then sintering for 60min at the pressure of 1600 ℃ and 24KN, stopping heating, and cooling to room temperature (the temperature and pressure in the hot-pressing sintering process are controlled as shown in figure 1), thus obtaining the ZrN-based multiphase ceramic.

The ceramic block prepared in this example was subjected to XRD, SEM observation, bulk density, mechanical strength, etc. tests, and the results were shown in fig. 2 to 7. The XRD pattern of the ZrN complex phase ceramic prepared in the embodiment is shown as a sample 3S9Z7L3Zr22ZN, and the XRD pattern is shown in figure 2, and the main phases ZrN and La can be seen from the XRD pattern_4.67Si₃O₁₃And also a small amount of ZrO₂(ii) a FIG. 3(a) shows the SEM microstructure of the ceramic sample prepared in this example, light gray as La_4.67Si₃O₁₃Phase, ZrN in dark grey and microporosity in black, it can be seen that La_4.67Si₃O₁₃Is uniformly and continuously distributed among ZrN crystal grain gaps and presents a random shape, and the size of the ZrN crystal grain is 20-50 mu m. The samples were subjected to the performance test, and the results are shown in FIGS. 4 to 7, respectively, in which the relative density was 96%, the hardness was 11.0GPa, the bending strength was 275.4MPa, and the fracture toughness was 2.03MPa.m^1/2。

Example 2

1) Selecting alpha-Si₃N₄Powder with purity of 99.9% and granularity less than or equal to 0.7 micron; ZrO (ZrO)₂Powder: the purity is 99.9 percent, and the granularity is less than or equal to 100 nm; la₂O₃Powder: the purity is 99.9 percent, and the granularity is less than or equal to 10 mu m; zr powder: purity 99.5%, particle size 200 mesh (200 mesh powder); ZrN powder: the purity is 99 percent, and the granularity is 400 meshes (powder is sieved by a 400-mesh sieve); wherein alpha-Si₃N₄、ZrO₂、La₂O₃A raw material powder, designated as 3S9Z7L3Zr44ZN, was prepared with a molar ratio of Zr powder to ZrN of m: n: x: y ═ 3:9:7:3: 44;

4) and (2) sintering the pressed and formed blank in a hot-pressing sintering furnace, heating to 1600 ℃ at the speed of about 20 ℃/min within 0-80min, pressurizing to 24KN at the speed of about 3KN/10min within 0-80min, then sintering for 60min at the temperature of 1600 ℃ and the pressure of 24KN, stopping heating, cooling to room temperature, and controlling the temperature and the pressure in the hot-pressing sintering process as shown in figure 1 to obtain the ZrN-based complex phase ceramic.

The ceramic block prepared in this example was subjected to XRD, SEM observation, bulk density, mechanical strength, etc. tests, and the results were shown in fig. 2 to 7. The XRD pattern of the ZrN complex phase ceramic prepared in the embodiment is shown as a sample 3S9Z7L3Zr44ZN, and the XRD pattern is shown in figure 2, and the main phases ZrN and La can be seen from the XRD pattern_4.67Si₃O₁₃(ii) a FIG. 3(b) shows the SEM microstructure of the ceramic sample prepared, light gray La_4.67Si₃O₁₃Phase, ZrN in dark grey and microporosity in black, it can be seen that La_4.67Si₃O₁₃Is uniformly and continuously distributed among ZrN crystal grain gaps and presents a random shape, and the size of the ZrN crystal grain is 20-50 mu m. The samples were subjected to the performance test, and the results are shown in FIGS. 4 to 7, respectively, in which the relative density was 98%, the hardness was 11.1GPa, the bending strength was 301.29MPa, and the fracture toughness was 2.01MPa.m^1/2。

Example 3

1) Selecting alpha-Si₃N₄Powder with purity of 99.9% and granularity less than or equal to 0.7 micron; ZrO (ZrO)₂Powder: the purity is 99.9 percent, and the granularity is less than or equal to 100 nm; la₂O₃The purity of the powder is 99.9 percent, and the granularity is less than or equal to 10 mu m; zr powder: purity 99.5%, particle size 200 mesh (200 mesh powder); ZrN powder: the purity is 99 percent, and the granularity is 400 meshes (powder is sieved by a 400-mesh sieve); wherein alpha-Si₃N₄、ZrO₂、La₂O₃A raw material powder, designated as 3S9Z7L3Zr66ZN, was prepared with a molar ratio of Zr powder to ZrN of m: n: x: y ═ 3:9:7:3: 66;

4) and (3) sintering the pressed and formed blank in a hot-pressing sintering furnace, controlling the temperature and the pressure in the hot-pressing sintering process as shown in figure 1, heating to 1600 ℃ at the speed of about 20 ℃/min within 0-80min, pressurizing to 24KN at the speed of about 3KN/10min within 0-80min, then sintering for 60min at the temperature of 1600 ℃ and 24KN under the pressure, stopping heating, and cooling to room temperature to obtain the ZrN-based complex phase ceramic.

The ceramic block prepared in this example was subjected to XRD, SEM observation, bulk density, mechanical strength, etc. tests, and the results were shown in fig. 2 to 7. The XRD pattern of the ZrN complex phase ceramic prepared in the embodiment is shown as a sample 3S9Z7L3Zr66ZN, and the XRD pattern is shown in figure 2, and the main phases ZrN and La can be seen from the XRD pattern_4.67Si₃O₁₃(ii) a FIG. 3(c) shows the SEM microstructure of the ceramic sample prepared, light gray La_4.67Si₃O₁₃Phase, ZrN in dark grey and microporosity in black, it can be seen that La_4.67Si₃O₁₃Is uniformly and continuously distributed among ZrN crystal grain gaps and presents a random shape, and the size of the ZrN crystal grain is 20-50 mu m. The samples were subjected to the performance test, and the results are shown in FIGS. 4 to 7, respectively, in which the relative density was 87%, the hardness was 11.4GPa, the bending strength was 250.6MPa, and the fracture toughness was 2.03MPa.m^1/2。

Comparative example 1

1) Selecting alpha-Si₃N₄Powder with purity of 99.9% and granularity less than or equal to 0.7 micron; ZrO (ZrO)₂Powder: the purity is 99.9 percent, and the granularity is less than or equal to 100 nm; la₂O₃Powder: the purity of the product is 99.9%,the particle size is less than or equal to 10 mu m; zr powder: purity 99.5%, particle size 200 mesh (200 mesh powder); ZrN powder: the purity is 99 percent, and the granularity is 400 meshes (powder is sieved by a 400-mesh sieve); wherein alpha-Si₃N₄、ZrO₂、La₂O₃A raw material powder, designated as 3S9Z7L3Zr88ZN, was prepared with a molar ratio of Zr powder to ZrN of m: n: x: y ═ 3:9:7:3: 88;

The ceramic block prepared in this comparative example was subjected to XRD, SEM observation, bulk density, mechanical strength, and the like, and the results were shown in fig. 2 to 7. The ZrN composite ceramic prepared by the comparative example is marked as a sample 3S9Z7L3Zr88ZN, the XRD pattern of the ZrN composite ceramic is shown in figure 2, and the main phases ZrN and La can be seen from the XRD pattern_4.67Si₃O₁₃(ii) a FIG. 3(d) shows the SEM microstructure of the ceramic sample prepared, light gray La_4.67Si₃O₁₃Phase, ZrN in dark grey and microporosity in black, it can be seen that La_4.67Si₃O₁₃Is uniformly and continuously distributed among ZrN crystal grain gaps and presents a random shape, and the size of the ZrN crystal grain is 20-50 mu m. The samples were subjected to the performance test, and the results are shown in FIGS. 4 to 7, respectively, in which the relative density was 87%, the hardness was 8.1GPa, the bending strength was 227.9MPa, and the fracture toughness was 2.51MPa.m^1/2。

Comparative example 2

1) Selecting alpha-Si₃N₄Powder with purity of 99.9% and granularity less than or equal to 0.7 micron; ZrO (ZrO)₂Powder: the purity is 99.9 percent, and the granularity is less than or equal to 100 nm; la₂O₃Powder: the purity is 99.9 percent, and the granularity is less than or equal to 10 mu m; zr powder: purity 99.5%, particle size 200 mesh (200 mesh powder); wherein alpha-Si₃N₄、ZrO₂、La₂O₃A raw material powder, designated as 3S9Z7L3Zr0ZN, was prepared with a molar ratio of Zr powder of m: n: x: y ═ 3:9:7: 3;

The ceramic block (denoted as sample 3S9Z7L3Zr0ZN) prepared in this comparative example was subjected to a performance test, and the results are shown in FIGS. 4 to 7, respectively, in which the relative density is 95%, the hardness is 8.4GPa, the bending strength is 252.3MPa, and the fracture toughness is 2.15MPa^1/2。

As can be seen from the differences of various properties of the ZrN ceramic blocks prepared in the examples 1-3 and the comparative examples 1-2, the proper addition of ZrN in the ZrN complex phase ceramic formula system is beneficial to the improvement of the mechanical properties, and the sample prepared in the example 2 has better mechanical properties, the relative density reaches 98%, the hardness reaches 11.1GPa, the bending strength reaches 301.29MPa, and the fracture toughness reaches 2.01MPa.m¹ ^/2However, the introduction of excessive ZrN can block Si₃N₄-ZrO₂-La₂O₃The mechanical property of the ceramic is reduced due to incomplete sintering of the ternary reaction, so that the ZrN addition range defined by the invention is a reasonable range capable of obtaining excellent ZrN-based ceramic materials.

Finally, it is further noted that, in the present invention, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

While the invention has been disclosed by the description of specific embodiments thereof, it will be appreciated that those skilled in the art will be able to devise various modifications, improvements, or equivalents thereof, within the spirit and scope of the appended claims. Such modifications, improvements and equivalents are intended to be included within the scope of the invention as claimed.

Claims

1. The ZrN-based ultrahigh-temperature ceramic is characterized in that the main phase of the ZrN-based ultrahigh-temperature ceramic comprises ZrN and La_4.67Si₃O₁₃Wherein, La_4.67Si₃O₁₃The ZrN crystal grains are uniformly and continuously distributed among the ZrN crystal grain gaps, and the size of the ZrN crystal grains is 20-50 mu m; the volume density of the ZrN-based ultrahigh-temperature ceramic is 87-98%, the hardness is 10.0-11.5GPa, the bending strength is 240-310MPa, and the fracture toughness is 1.90-2.05MPa.m^1/2。

2. The ZrN based SUPER of claim 1The high-temperature ceramic is characterized in that the volume density of the ZrN-based ultrahigh-temperature ceramic is 95-98%, the hardness is 10.5-11.2GPa, the bending strength is 275-302MPa, and the fracture toughness is 1.94-2.05MPa.m^1/2。

3. A hot-pressing reaction sintering preparation method of ZrN-based ultrahigh-temperature ceramic is characterized by comprising the following steps:

the hot-pressing reaction sintering treatment step: carrying out hot-pressing sintering treatment on the formed blank to obtain the ZrN-based ultrahigh-temperature ceramic;

wherein, in the raw material pretreatment step, the alpha-Si is₃N₄Expressed in m, said ZrO₂Is represented by n, and the La₂O₃The mol number of the Zr powder is expressed by x, the mol number of the Zr powder is expressed by y, the mol number of the ZrN powder is expressed by z, and the preferable mixture ratio of the raw materials is as follows: m, n, x, y, z, 3, 9, 7, 3, (22-66).

4. The method for preparing ZrN based UHT ceramics according to claim 3, wherein in the raw material pretreatment step, the α -Si is used as a raw material₃N₄The purity of the product is more than 99.9 percent, and the granularity is less than 0.7 mu m; the ZrO₂The purity of the product is more than 99.9 percent, and the granularity is less than 100 nm; the La₂O₃The purity of the product is more than 99.9 percent, and the granularity is less than 10 mu m; the purity of the Zr powder is more than 99.5 percent, and the granularity is less than 75 mu m; the ZrN powder has a purity of 99% and a particle size of 38 μm or less.

5. The method for preparing ZrN based ultra high temperature ceramic by hot pressing reactive sintering as claimed in claim 3 or 4, wherein in the raw material pretreatment step, the auxiliary agent is ethanol.

6. The method for preparing ZrN based ultra high temperature ceramic by hot pressing reaction sintering according to any one of claims 3 to 5, wherein in the raw material pretreatment step, the time of the ball milling treatment is 30 to 180min, and the rotation speed of the ball mill is set to 500-.

7. A ZrN based ultra high temperature ceramic hot pressing reaction sintering preparation method as claimed in any one of claims 3-6, wherein in the raw material pretreatment step, the temperature of the drying treatment is 90-110 ℃ for 3-12 h.

8. A ZrN-based hot-pressing reaction sintering production method of an ultrahigh-temperature ceramic according to any one of claims 3 to 7, wherein in the forming treatment step, the pressure is 2MPa to 5MPa.

9. The method for preparing ZrN based ultra high temperature ceramic by hot pressing reaction sintering as claimed in any one of claims 3 to 8, wherein in the step of hot pressing reaction sintering treatment, the sintering temperature is 1550-.

10. The method for preparing ZrN-based ultra high temperature ceramic by hot-pressing reaction sintering according to claim 9, wherein in the hot-pressing reaction sintering step, the temperature is increased to 1600 ℃ at a constant speed within 0-80min, the pressure is increased to 24KN at a constant speed within 0-80min, then the ZrN-based ultra high temperature ceramic is prepared by sintering at 1600 ℃ and 24KN for 60-80min, then the heating is stopped, and the temperature is reduced to room temperature.