A method for preparing a zirconium boride-based porous ultrahigh temperature ceramic

Abstract

The application discloses a preparation method of zirconium boride-based porous ultrahigh-temperature ceramic, and the method comprises the following steps: obtaining at least two kinds of zirconium boride powder with different particle sizes, mixing the obtained zirconium boride powder, and drying the mixed zirconium boride powder to obtain zirconium boride-based powder; the obtained zirconium boride-based powder is loosely stacked in a sintering container; the sintering container containing the zirconium boride-based powder is sintered in a protective gas atmosphere, and then zirconium boride-based porous ultrahigh-temperature ceramic is obtained. The preparation method provided by the application can quickly prepare zirconium boride-based porous ultrahigh-temperature ceramic, and the prepared zirconium boride-based porous ultrahigh-temperature ceramic has the characteristics of high compressive strength and low thermal conductivity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ultra-high-temperature ceramic material preparation, and particularly relates to a preparation method of zirconium boride-based porous ultra-high-temperature ceramic. BACKGROUND

[0002] The surface temperature of aerospace vehicles such as supersonic aircraft can reach 2000℃ during long-time flight. In order to ensure that the internal structure of the aircraft is not damaged and the electronic devices are normally operated at high temperature, the thermal protection material used is required to have good heat insulation capacity and mechanical properties at high temperature. However, the existing phenolic foam composite materials, alumina foam ceramics, aerogels and other thermal insulation materials generally have the problems of insufficient temperature resistance and poor mechanical properties, and are difficult to meet the performance requirements.

[0003] Zirconium boride, as the most important component of ultra-high-temperature ceramic materials, has a melting point of 3245℃ and good oxidation resistance and mechanical properties at ultra-high temperature. By introducing a porous structure to reduce the thermal conductivity of zirconium boride, it can play a huge potential in the field of ultra-high-temperature thermal insulation. Therefore, how to prepare a zirconium boride-based porous ultra-high-temperature ceramic with good performance and simple process has been a technical problem to be solved by technical personnel in the technical field. SUMMARY

[0004] To solve the above technical problems, the application provides a preparation method of zirconium boride-based porous ultra-high-temperature ceramic, comprising:

[0005] Obtaining at least two kinds of zirconium boride powders with different particle sizes, and mixing and drying the obtained zirconium boride powders to obtain a zirconium boride-based powder;

[0006] Loosely stacking the obtained zirconium boride-based powder in a sintering container;

[0007] Sintering the sintering container containing the zirconium boride-based powder in a protective gas atmosphere to obtain a zirconium boride-based porous ultra-high-temperature ceramic.

[0008] In some embodiments, the purity of the zirconium boride powder is 95.00%-99.95%, and the particle size range is 2-30μm.

[0009] In some embodiments, the mixing of the obtained zirconium boride powder is specifically: selecting anhydrous ethanol as a medium, and wet mixing the obtained at least two kinds of zirconium boride powders with different particle sizes based on a magnetic stirring method, and the wet mixing time is 4-8h.

[0010] In some embodiments, the obtained zirconium boride-based powder is loosely stacked in the sintering container, specifically: firstly, the obtained zirconium boride-based powder is placed on a weighing paper; then the zirconium boride-based powder on the weighing paper is manually poured into the sintering container and the zirconium boride-based powder is loosely stacked in the sintering container; finally, the sintering container is gently shaken to make the surface of the zirconium boride-based powder flat.

[0011] In some embodiments, the sintering container is a high-purity graphite crucible.

[0012] In some embodiments, the sintering container loaded with the zirconium boride-based powder is sintered, specifically: the sintering container loaded with the zirconium boride-based powder is placed in an induction heating furnace, the induction heating furnace is heated to a sintering temperature at a preset heating rate in a protective gas atmosphere, and the sintering temperature is maintained for a preset time, and then the furnace is cooled, to obtain a zirconium boride-based porous ultra-high temperature ceramic.

[0013] In some embodiments, the preset heating rate is 5-15℃ / min, the sintering temperature is 1900-2200℃, and the preset time is 1-2h.

[0014] In some embodiments, the pressure of the protective gas is 10Pa-0.1MPa.

[0015] In some embodiments, the protective gas is an inert gas.

[0016] Compared with the prior art, the present application provides a preparation method of a zirconium boride-based porous ultra-high temperature ceramic. The preparation method does not need to add sintering aids and pore-forming agents, only needs to mix a plurality of zirconium boride powders with different particle sizes and then perform loose sintering, to prepare a zirconium boride-based porous ultra-high temperature ceramic. Moreover, under the premise that the porosity of the prepared zirconium boride-based porous ultra-high temperature ceramic is 40-50%, the comprehensive performance of the zirconium boride-based porous ultra-high temperature ceramic can achieve a compression strength greater than 200MPa and a thermal conductivity lower than 35W / (m·K). Therefore, the performance of the product prepared by the preparation method is better than that of the product prepared by the prior art. The preparation method provided by the present application can not only improve the performance of the product, but also reduce the time cost and economic cost caused by the complicated preparation process, and has a good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a flowchart of a preparation method of a zirconium boride-based porous ultra-high temperature ceramic in the present application,

[0018] Figure 2 is a test result schematic diagram of the porosity and compression strength of the zirconium boride-based porous ultra-high temperature ceramic prepared by three embodiments of the present application,

[0019] Figure 3This is a schematic diagram showing the test results of porosity and thermal conductivity of the zirconium boride-based porous ultra-high temperature ceramics prepared according to the three embodiments of this application.

[0020] Figure 4 This is a scanning electron microscope image of the product prepared in Example 1 of this application at 1000x magnification.

[0021] Figure 5 This is a scanning electron microscope image of the product prepared in Example 2 of this application at 1000x magnification.

[0022] Figure 6 This is a scanning electron microscope image of the product prepared in Example 3 of this application under 1000x magnification. Detailed Implementation

[0023] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0024] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0025] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0026] In order to enable a more clearer understanding of the above-mentioned purposes, features and advantages of the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments, additional embodiments and advantages of the present application will be partially given in the following description, partially will become obvious from the following description, or will be understood by practice. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0027] In the present application, the zirconium boride powder with different particle sizes contains two or more particle sizes, and the shape is irregular, and the particle size distribution is 2-30 μm, and the purity of each particle size of the zirconium boride powder is 95.00-99.95%.

[0028] As shown in Figure 1 A method for preparing a zirconium boride-based porous ultrahigh-temperature ceramic, the method comprising the following steps:

[0029] Obtaining at least two kinds of zirconium boride powder with different particle sizes, and mixing the obtained zirconium boride powder in the required proportion after drying to obtain a zirconium boride-based powder;

[0030] In this step, the mixing of the obtained zirconium boride powder is specifically: selecting anhydrous ethanol as a medium, and wet mixing the obtained at least two kinds of zirconium boride powder with different particle sizes based on a magnetic stirring method, and the wet mixing time is 4-8 h.

[0031] The obtained zirconium boride-based powder is loosely packed in a sintering container;

[0032] This step is specifically: first, the obtained zirconium boride-based powder is placed on a weighing paper; then the zirconium boride-based powder on the weighing paper is manually poured into the sintering container and the zirconium boride-based powder is loosely packed in the sintering container; finally, the sintering container is gently shaken to make the surface of the zirconium boride-based powder flat;

[0033] The sintering container is a high-purity graphite crucible.

[0034] The sintering container containing the zirconium boride-based powder is sintered under a protective gas atmosphere, and a zirconium boride-based porous ultrahigh-temperature ceramic is obtained;

[0035] This step specifically includes: placing the sintering container containing the zirconium boride-based powder in an induction heating furnace, and heating the induction heating furnace to a sintering temperature at a preset heating rate in a protective gas atmosphere, and keeping the sintering temperature for a preset time and then cooling with the furnace to obtain a zirconium boride-based porous ultrahigh-temperature ceramic;

[0036] The preset temperature increasing rate is 5-15℃ / min, such as 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min, 15℃ / min, etc.

[0037] The sintering temperature is 1900-2200℃, such as 1900℃, 1950℃, 2000℃, 2050℃, 2100℃, 2150℃, 2200℃, etc.

[0038] The preset time is 1-2h, such as 1h, 1.5h, 2h, etc.

[0039] In the above embodiment, the pressure of the protective gas is 10Pa-0.1MPa, and the protective gas is inert gas, such as helium, argon, nitrogen, etc. In this embodiment, argon is preferred.

[0040] In this embodiment, first, at least two kinds of zirconium boride powders with different particle sizes are selected according to the required proportion, and the obtained zirconium boride powders are mixed and dried to obtain a zirconium boride-based powder; then, the zirconium boride-based powder is loosely packed in a sintering container; finally, the sintering container with loosely packed zirconium boride-based powder is sintered in a protective gas atmosphere, thereby obtaining a zirconium boride-based porous ultra-high temperature ceramic. In the preparation method provided in the present application, no sintering aid and pore-forming agent needs to be added, only a simple powder mixing and loose packing and loose sintering of multiple zirconium boride powders with different particle sizes according to the required proportion are needed, and a high-performance zirconium boride-based porous ultra-high temperature ceramic can be prepared. Under the premise of a porosity of 40-50%, the comprehensive performance of the zirconium boride-based porous ultra-high temperature ceramic can realize a compressive strength greater than 200MPa and a thermal conductivity lower than 35W / (m·K). Therefore, the preparation method provided can not only improve the performance of the product, but also reduce the time cost and economic cost caused by the complicated preparation process, and has good application prospect.

[0041] In order to better illustrate the working principle and technical effects of the present application, three examples are described below. It should be noted that in Examples 1-3, D represents the particle size of the zirconium boride powder.

[0042] Example 1

[0043] Two kinds of zirconium boride powders with irregular shapes and particle sizes of D=10μm and D=30μm were weighed according to a ratio of (30:70)vol%;

[0044] The two kinds of zirconium boride powders were mixed by magnetic stirring method with anhydrous ethanol as the medium, and the mixing time was 4h;

[0045] The mixed powder is dried in a 50°C oven to obtain the "zirconium boride-based powder" for sintering;

[0046] The dried zirconium boride-based powder is placed on a weighing paper and then manually poured to make the zirconium boride-based powder loosely accumulate in a high-purity graphite crucible. The crucible is gently shaken to make the upper surface of the zirconium boride-based powder in the crucible flat, and no pressure is applied during the process;

[0047] The high-purity graphite crucible containing the zirconium boride-based powder is placed in an induction heating furnace, and heated to 2200°C at a temperature rising rate of 10°C / min under an argon protective atmosphere of 10 Pa. After holding for 2 h, the furnace is cooled to obtain a zirconium boride-based porous ultrahigh-temperature ceramic material.

[0048] Example 2

[0049] Two kinds of zirconium boride powders with irregular shapes and particle size distributions of D=2 μm and D=10 μm are weighed in a ratio of (10:90) vol%;

[0050] The two kinds of zirconium boride powders are mixed by a magnetic stirring method with anhydrous ethanol as a medium, and the mixing time is 5 h;

[0051] The mixed zirconium boride powder is dried in a 50°C oven to obtain the "zirconium boride-based powder" for sintering;

[0052] The "zirconium boride-based powder" for sintering is placed on a weighing paper and then manually poured to make the zirconium boride-based powder loosely accumulate in a high-purity graphite crucible. The crucible is gently shaken to make the upper surface of the zirconium boride-based powder in the crucible flat, and no pressure is applied during the process;

[0053] The high-purity graphite crucible containing the "zirconium boride-based powder" is placed in an induction heating furnace, and heated to 2000°C at a temperature rising rate of 5°C / min under an argon protective atmosphere of 100 Pa. After holding for 1 h, the furnace is cooled to obtain a zirconium boride-based porous ultrahigh-temperature ceramic material.

[0054] Example 3

[0055] Three kinds of zirconium boride powders with irregular shapes and particle size distributions of D=2 μm, D=10 μm and D=15 μm are weighed in a ratio of (20:60:20) vol% to obtain "mixed zirconium boride powder";

[0056] The three kinds of mixed zirconium boride powders are mixed by a magnetic stirring method with anhydrous ethanol as a medium, and the mixing time is 8 h;

[0057] The mixed zirconium boride powder is dried in a 50°C oven to obtain the "zirconium boride-based powder" for sintering;

[0058] The "zirconium boride-based powder" for sintering is placed on a weighing paper, and then is manually poured to make the zirconium boride-based powder loosely pile up in a high-purity graphite crucible, and the crucible is gently shaken to make the upper surface of the zirconium boride-based powder flat, without applying any pressure during the process;

[0059] The high-purity graphite crucible containing the "zirconium boride-based powder" is placed in an induction heating furnace, and is heated to 1900℃ at a heating rate of 15℃ / min under an argon protective atmosphere at 0.1MPa, and is cooled with the furnace after being kept at 1900℃ for 2h, to obtain a zirconium boride-based porous ultrahigh-temperature ceramic material.

[0060] As shown in Figure 4 , Figure 5 and Figure 6 , the zirconium boride-based porous ultrahigh-temperature ceramic prepared in Examples 1-3 is subjected to scanning electron microscopy analysis, and the zirconium boride-based porous ultrahigh-temperature ceramic prepared in the examples is subjected to porosity, thermal conductivity and compressive strength tests according to national standards, and the test results are shown in Figure 2 and Figure 3 , in which: ① represents Example 1, ② represents Example 2, and ③ represents Example 3.

[0061] As can be seen from Figures 4-6 , the zirconium boride-based porous ultrahigh-temperature ceramic obtained in Examples 1-3 is of a porous structure; as can be seen from Figure 2 and Figure 3 , the zirconium boride-based porous ultrahigh-temperature ceramic material prepared in Examples 1-3 has a porosity of 40-50%, a compressive strength greater than 200MPa, and a thermal conductivity lower than 35W / (m·K); therefore, the zirconium boride-based porous ultrahigh-temperature ceramic prepared in the present embodiment has the characteristics of high compressive strength and low thermal conductivity, the comprehensive performance is improved, the time and economic cost caused by the complicated preparation process are reduced under the premise of ensuring good performance, and the zirconium boride-based porous ultrahigh-temperature ceramic has a good application prospect in the fields of aerospace and military.

[0062] The above describes in detail a method for preparing a zirconium boride-based porous ultrahigh-temperature ceramic according to the present application. In this paper, specific examples are applied to explain the principles and implementation modes of the present application, and the above description of examples is only used to help understand the core idea of the present application. It should be pointed out that, for those skilled in the art, without departing from the principles of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A method for preparing a zirconium boride-based porous ultrahigh-temperature ceramic, characterized by, The application relates to a zirconium boride-based porous ultra-high-temperature ceramic and a preparation method thereof. The zirconium boride-based powder is obtained by mixing and drying at least two kinds of zirconium boride powders with different particle sizes; The zirconium boride-based powder is loosely stacked in a sintering container, specifically: the zirconium boride-based powder is first placed on a weighing paper; then the zirconium boride-based powder on the weighing paper is manually poured into the sintering container and is loosely stacked in the sintering container; finally, the sintering container is gently shaken to make the surface of the zirconium boride-based powder flat, and no pressure is applied during the process; The sintering container containing the zirconium boride-based powder is sintered in a protective gas atmosphere, and a zirconium boride-based porous ultra-high-temperature ceramic is obtained, specifically: the sintering container containing the zirconium boride-based powder is placed in an induction heating furnace, the induction heating furnace is heated to a sintering temperature at a preset heating rate in a protective gas atmosphere, and the sintering temperature is maintained for a preset time and then the furnace is cooled, wherein the preset heating rate is 5-15 DEG C / min, the sintering temperature is 1900-2200 DEG C, and the preset time is 1-2 h, so that the zirconium boride-based porous ultra-high-temperature ceramic is obtained. In the preparation process of the zirconium boride-based porous ultra-high-temperature ceramic, no sintering aid and pore-forming agent needs to be added, and under the premise that the porosity of the prepared zirconium boride-based porous ultra-high-temperature ceramic is 40-50%, the compressive strength is greater than 200 MPa, and the thermal conductivity is lower than 35 W / m.K.

2. The method of claim 1, wherein the zirconium boride-based porous ultrahigh-temperature ceramic is prepared by a method comprising: The purity of the zirconium boride powder is 95.00%-99.95%, and the particle size range is 2-30 mu m.

3. The method of making a zirconium boride-based porous ultrahigh-temperature ceramic according to claim 2, wherein, The mixing of the obtained zirconium boride powder is specifically: anhydrous ethanol is selected as the medium, and the obtained at least two kinds of zirconium boride powders with different particle sizes are wet mixed based on a magnetic stirring method, and the wet mixing time is 4-8 h.

4. The method of claim 3, wherein the zirconium boride-based porous ultrahigh-temperature ceramic is prepared by a method comprising: The sintering container is a high-purity graphite crucible.

5. The method of claim 4, wherein the zirconium boride-based porous ultrahigh-temperature ceramic is prepared by a method comprising: The protective gas pressure is 10 Pa-0.1 MPa.

6. The method of making a zirconium boride-based porous ultrahigh-temperature ceramic according to claim 5, wherein, The protective gas is an inert gas.

Images