A high-entropy ultra-high-temperature ceramic-based composite material and its preparation method

Abstract

The present application belongs to the field of high entropy ultrahigh temperature ceramics, specifically a high entropy ultrahigh temperature ceramic matrix composite material and its preparation method. The composite material is obtained by the following method: firstly, a transition metal element and silicon powder are used as raw materials to synthesize (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )Si2 powder; then (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )Si2, B4C and C powders were mixed uniformly in a molar ratio of 2:1:3 and sintered in situ; finally, a dense (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2‑SiC composite materials.

Description

Technical Field

[0001] The present application relates to the field of high-entropy and ultra-high-temperature ceramics, and specifically to a high-entropy and ultra-high-temperature ceramic-based composite material and a preparation method thereof. Background Art

[0002] High-entropy boride ceramics (HEB) have strong covalent bonds between metal atoms and boron atoms, and between boron atoms, giving them a high melting point. The synergistic effect of lattice distortion and solid solution strengthening due to atomic-scale differences endows them with excellent temperature resistance, making them have great application potential in extreme environments such as ultrahigh-temperature thermal protection and critical metal smelting. The strong covalent bonding and low diffusion coefficient of HEB ceramics mean that the synthesis and densification of HEB powders usually require temperatures above 2000°C (High-Entropy Metal Diborides: A New Class of High-Entropy Materials and a New Type of Ultrahigh Temperature Ceramics, 2016, 6(1):37946). Excessively high sintering temperatures will cause abnormal grain growth, thereby affecting the mechanical properties of high-entropy boride ceramics (Dense and pure high-entropy metaldiboride ceramics sintered from self-synthesized powders via boro / carbothermal reduction approach, 2019, 62(12):1898-1909). Composite SiC particles can introduce a grain boundary pinning mechanism, thereby inhibiting the excessive growth of HEB grains and refining the material's microstructure, thereby achieving a synergistic improvement in the density and mechanical properties of HEB ceramics (Mechanical properties of hot-pressed high-entropy diboride-based ceramics, 2020, 9(4):8).

[0003] Currently, the preparation process for HEB-SiC composites typically involves the synthesis of HEB powder, mixing with SiC powder, and densification of the final composite. However, this process still faces key challenges such as high preparation temperature, uneven phase distribution, and low material density. Therefore, developing a low-temperature, efficient method for preparing HEB-SiC composites will greatly promote the practical engineering application of this material system. Summary of the Invention

[0004] This application is based on the above technical problems. This application aims to provide a high entropy ultra-high temperature ceramic matrix composite material and a preparation method thereof. First, a transition metal element and silicon powder are used as raw materials to synthesize (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )Si2 powder; then (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )Si2, B4C and C powders were mixed evenly in a molar ratio of 2:1:3 and placed in a sintering furnace for in-situ reaction sintering; finally, a dense (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2-SiC composite material.

[0005] According to the first aspect of the present application, a method for preparing a high-entropy ultrahigh-temperature ceramic-based composite material is proposed, comprising the following steps:

[0006] V powder, Nb powder, Cr powder, Mo powder, W powder, and Si powder in a molar ratio of 1:1:1:1:1:10 were mixed with anhydrous ethanol and ball-milled to obtain powder A;

[0007] The powder A is subjected to hot pressing sintering or spark plasma sintering under vacuum or protective atmosphere; and then sieved through a 100-300 mesh sieve to obtain powder S; during the sintering process of the powder A, the heating rate is 10-100°C / min, the reaction temperature is 1600-1800°C, the reaction pressure is 20-60 MPa, and the reaction time is 10-120 min;

[0008] The powder S, B4C powder and C powder in a molar ratio of 2:1:3 were mixed with anhydrous ethanol and ball-milled to obtain powder Y;

[0009] The powder Y is subjected to in-situ reaction sintering under vacuum or protective atmosphere to obtain (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 ) B2-SiC; the in-situ reaction sintering process has a heating rate of 10~100 ℃ / min, a sintering temperature of 1600~1800 ℃, a sintering pressure of 20~60MPa, and a holding time of 10~120min.

[0010] In some embodiments, during the preparation of the powder A, the grinding balls used in the ball milling process are ZrO2 grinding balls; the ball-to-material ratio is 1-3:1, the ball milling speed is 90-400 r / min, and the ball milling time is 4-24 h.

[0011] In some embodiments, during the preparation of the powder S, the powder A is transferred to a graphite mold, and then placed in a hot pressing sintering furnace or a spark plasma sintering furnace for solid solution under vacuum or protective atmosphere.

[0012] In some embodiments, the product after solid solution is crushed and passed through a 100-300 mesh sieve to obtain the powder S.

[0013] In some embodiments, during the preparation of the powder Y, the grinding balls used in the ball milling process are ZrO2 grinding balls; the ball-to-material ratio is 1-3:1, the ball milling speed is 90-400 r / min, and the ball milling time is 4-24 h.

[0014] In some embodiments, during the preparation of the powder Y, the powder Y is transferred to a graphite mold, and then placed in a hot pressing sintering furnace or a spark plasma sintering furnace for in-situ reaction sintering under vacuum or a protective atmosphere.

[0015] In some embodiments, the chemical reaction occurring during in-situ reaction sintering is:

[0016] 2(V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )Si2+B4C+3C→2(V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2+4SiC.

[0017] According to the second aspect of the present application, a high entropy ultrahigh temperature ceramic matrix composite material is proposed. The molecular formula of the high entropy ultrahigh temperature ceramic matrix composite material is (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2-SiC.

[0018] Compared with the related art, this application has the following technical effects:

[0019] (1) This application is prepared by in-situ reaction sintering (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2)Compared with the conventional preparation method of HEB-SiC composite materials, the in-situ reaction sintering method of B2-SiC composite materials can simultaneously achieve low-temperature in-situ synthesis of HEB phase and low-temperature densification of HEB-SiC composite materials.

[0020] (2) This application provides an in-situ reaction sintering method for preparing (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 ) The method for preparing B2-SiC composite material has low preparation temperature, uniform phase distribution and high material density. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 ) Si2 powder XRD pattern;

[0022] Figure 2 (V prepared in Example 1-2 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 ) XRD pattern of B2-SiC composite material;

[0023] Figure 3 (V prepared in Example 1 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 ) SEM image of B2-SiC composite material;

[0024] Figure 4 The (V prepared in Example 1 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 ) EDS image of B2-SiC composite material. DETAILED DESCRIPTION

[0025] In order to more clearly understand the above-mentioned objects, 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. It should be noted that the embodiments of the present application and the features therein can be combined with each other in the absence of conflict.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0027] According to the first aspect of the present application, a method for preparing a high-entropy ultrahigh-temperature ceramic-based composite material is proposed, comprising the following steps:

[0028] S1: V powder, Nb powder, Cr powder, Mo powder, W powder and Si powder in a molar ratio of 1:1:1:1:1:10 were mixed with anhydrous ethanol and ball milled to obtain powder A;

[0029] S2: Powder A is subjected to hot pressing or spark plasma sintering under vacuum or protective atmosphere; then passed through a 100-300 mesh sieve to obtain powder S; during the sintering process of powder A, the heating rate is 10-100°C / min, the reaction temperature is 1600-1800°C, the reaction pressure is 20-60 MPa, and the reaction time is 10-120 min;

[0030] S3: Powders S, B4C powder, and C powder in a molar ratio of 2:1:3 were mixed with anhydrous ethanol and ball-milled to obtain powder Y;

[0031] S4: Powder Y is subjected to in-situ reaction sintering under vacuum or protective atmosphere to obtain (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2-SiC; during the in-situ reaction sintering process, the heating rate is 10~100℃ / min, the sintering temperature is 1600~1800℃, the sintering pressure is 20~60MPa, and the holding time is 10~120min.

[0032] Among them, the V powder used in the embodiment of the present application has a purity of 99.90% and a particle size of 45 μm, the Nb powder used has a purity of 99.95% and a particle size of 45 μm, the Cr powder used has a purity of 99.90% and a particle size of 75 μm, the Mo powder used has a purity of 99.00% and a particle size of 45 μm, the W powder used has a purity of 99.95% and a particle size of 45 μm, the Si powder used has a purity of 99.99% and a particle size of 45 μm, the B4C powder used has a purity of 92% and a particle size of 1~3 μm, and the C powder used has a purity of 99.5% and a particle size of 48 μm. In S1, V powder, Nb powder, Cr powder, Mo powder, W powder, and Si powder in a molar ratio of 1:1:1:1:1:10 are placed in a polytetrafluoroethylene ball mill together with anhydrous ethanol and ZrO2 grinding balls, and a uniformly mixed powder A is obtained after ball milling. The ball-to-material ratio during the ball milling process is 1 to 3:1, the ball milling speed is 90 to 400 r / min, and the ball milling time is 4 to 24 hours. In the embodiment, the ball-to-material ratio during the ball milling process can be 1:1, 2:1, 3:1, etc.; the ball milling speed can be 90 r / min, 100 r / min, 200 r / min, 300 r / min, and 400 r / min, etc.; and the ball milling time can be 4 hours, 8 hours, 10 hours, 16 hours, and 24 hours, etc.

[0033] In S2, powder A is transferred to a graphite mold and placed in a hot pressing furnace or a spark plasma sintering furnace under vacuum or a protective atmosphere for solid solution. Powder S is then crushed and passed through a 100-300 mesh sieve to obtain powder S. The solid solution process parameters are as follows: a heating rate of 10-100°C / min, a reaction temperature of 1600-1800°C, a reaction pressure of 20-60 MPa, and a reaction time of 10-120 min. For example, the solid solution process parameters include heating rates of 10°C / min, 20°C / min, 40°C / min, 70°C / min, 100°C / min, etc.; reaction temperatures of 1600°C, 1700°C / min, 1800°C / min, etc.; reaction pressures of 20 MPa, 30 MPa, 50 MPa, 60 MPa; and reaction times of 10 min, 30 min, 50 min, 60 min, 80 min, 100 min, 120 min, etc.

[0034] In S3, S powder, B4C powder, and C powder at a molar ratio of 2:1:3 are placed in a polytetrafluoroethylene ball mill along with anhydrous ethanol and ZrO2 grinding balls. A uniformly mixed powder Y is obtained after ball milling. The ball-to-material ratio during the ball milling process is 1-3:1, the ball milling speed is 90-400 r / min, and the ball milling time is 4-24 hours. The ball-to-material ratio can be 1:1, 2:1, or 3:1, among others; the ball milling speed can be 90 r / min, 100 r / min, 200 r / min, 300 r / min, and 400 r / min, among others; and the ball milling time can be 4 hours, 8 hours, 10 hours, 16 hours, or 24 hours.

[0035] In S4, powder Y is transferred to a graphite mold and placed in a hot pressing sintering furnace or a spark plasma sintering furnace under vacuum or a protective atmosphere for in-situ reaction sintering. The process parameters of the in-situ reaction sintering are as follows: a heating rate of 10-100°C / min, a sintering temperature of 1600-1800°C, a sintering pressure of 20-60 MPa, and a holding time of 10-120 min. For example, the heating rate in the in-situ reaction sintering is 10°C / min, 20°C / min, 40°C / min, 70°C / min, 100°C / min, etc.; the reaction temperature is 1600°C, 1700°C / min, 1800°C / min, etc.; the reaction pressure is 20 MPa, 30 MPa, 50 MPa, 60 MPa; and the reaction time is 10 min, 30 min, 50 min, 60 min, 80 min, 100 min, 120 min, etc.

[0036] The chemical reactions that occur during in-situ reaction sintering are:

[0037] 2(V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )Si2+B4C+3C→2(V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2+4SiC.

[0038] Example 1

[0039] (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 ) The preparation method of the B2-SiC composite material is as follows:

[0040] (1) V powder, Nb powder, Cr powder, Mo powder, W powder and Si powder with a molar ratio of 1:1:1:1:1:10 were placed in a polytetrafluoroethylene ball mill together with anhydrous ethanol and ZrO2 grinding balls, and a uniformly mixed powder A was obtained after ball milling; the ball-to-material ratio during the ball milling process was 1:1, the ball milling speed was 300 r / min, and the ball milling time was 12 h;

[0041] (2) Powder A was transferred to a graphite mold and placed in a hot pressing furnace for solution treatment under vacuum conditions. Powder S was then crushed and passed through a 100-mesh sieve to obtain powder S. The solution treatment process parameters were as follows: heating rate of 10°C / min, reaction temperature of 1600°C, reaction pressure of 30 MPa, and reaction time of 60 min.

[0042] (3) S powder, B4C powder and C powder with a molar ratio of 2:1:3 were placed in a polytetrafluoroethylene ball mill together with anhydrous ethanol and ZrO2 grinding balls, and a uniformly mixed powder Y was obtained after ball milling; the ball-to-material ratio during the ball milling process was 1:1, the ball milling speed was 300 r / min, and the ball milling time was 6 h;

[0043] (4) Powder Y was transferred to a graphite mold and placed in a spark plasma sintering furnace for in-situ reaction sintering under vacuum conditions. The process parameters of the in-situ reaction sintering were as follows: heating rate of 100°C / min, sintering temperature of 1600°C, sintering pressure of 20 MPa, and holding time of 15 min. 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )The density of B2-SiC composite material is 82%.

[0044] Example 2

[0045] (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 ) The preparation method of the B2-SiC composite material is as follows:

[0046] (1) V powder, Nb powder, Cr powder, Mo powder, W powder and Si powder with a molar ratio of 1:1:1:1:1:10 were placed in a polytetrafluoroethylene ball mill together with anhydrous ethanol and ZrO2 grinding balls, and a uniformly mixed powder A was obtained after ball milling; the ball-to-material ratio during the ball milling process was 3:1, the ball milling speed was 150 r / min, and the ball milling time was 24 h;

[0047] (2) Powder A was transferred to a graphite mold and placed in a hot pressing furnace in an argon atmosphere for solid solution. Powder S was then crushed and passed through a 200-mesh sieve to obtain powder S. The solid solution process parameters were as follows: heating rate of 5°C / min, reaction temperature of 1600°C, reaction pressure of 20 MPa, and reaction time of 90 min.

[0048] (3) S powder, B4C powder and C powder with a molar ratio of 2:1:3 were placed in a polytetrafluoroethylene ball mill together with anhydrous ethanol and ZrO2 grinding balls, and a uniformly mixed powder Y was obtained after ball milling; the ball-to-material ratio during the ball milling process was 3:1, the ball milling speed was 90 r / min, and the ball milling time was 24 h;

[0049] (4) Powder Y was transferred to a graphite mold and placed in a spark plasma sintering furnace for in-situ reaction sintering under vacuum conditions. The process parameters of the in-situ reaction sintering were as follows: heating rate of 50°C / min, sintering temperature of 1800°C, sintering pressure of 60 MPa, and holding time of 15 min.

[0050] The (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2-SiC composite material density is 100%.

[0051] Example 3

[0052] (1) The (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 ) Si2 powder was tested by XRD. Figure 1 As shown, the results show that this method successfully synthesized (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )Si2 powder.

[0053] (2) The (V obtained in Example 1-2 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2-SiC composite material was tested by XRD. Figure 2 As shown, the results show that the composite material prepared by this method is composed of (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )It is composed of two phases: B2 and SiC.

[0054] (3) The (V prepared in Example 1 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2-SiC composite material surface SEM test Figure 3 As shown, the results show that the generated (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2 and SiC are evenly distributed, SiC is distributed in (V0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2 phase grain boundary.

[0055] (4) The (V prepared in Example 1 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 ) EDS test of B2-SiC composite material Figure 4 As shown, the results show that the composite material is composed of (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2 and SiC two phases, and the elements are evenly distributed.

[0056] The above are only preferred embodiments of the present application and are not intended to limit the present application. It should be understood that the in-situ reaction method for preparing high-entropy ultra-high temperature ceramic-based composite materials proposed in this application can be extended to high-entropy ceramic systems of other components, and there are many combinations of process parameters involved. Therefore, all technical solutions that can be obtained through logical analysis, reasoning or limited experiments based on the concept of this application on the basis of the existing technology are within the scope of protection determined by the claims.

Claims

1. A method for preparing a high-entropy ultrahigh-temperature ceramic-based composite material, characterized in that: The following steps are involved: V powder, Nb powder, Cr powder, Mo powder, W powder, and Si powder in a molar ratio of 1:1:1:1:1:10 were mixed with anhydrous ethanol and ball-milled to obtain powder A; The powder A is subjected to hot pressing sintering or spark plasma sintering under vacuum or protective atmosphere; and then sieved through a 100-300 mesh sieve to obtain powder S; during the sintering process of the powder A, the heating rate is 10-100°C / min, the reaction temperature is 1600-1800°C, the reaction pressure is 20-60 MPa, and the reaction time is 10-120 min; The powder S, B4C powder and C powder in a molar ratio of 2:1:3 were mixed with anhydrous ethanol and ball-milled to obtain powder Y; The powder Y is subjected to in-situ reaction sintering under vacuum or protective atmosphere to obtain (V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 ) B2-SiC; the in-situ reaction sintering process has a heating rate of 10 to 100°C / min, a sintering temperature of 1600 to 1800°C, a sintering pressure of 20 to 60 MPa, and a holding time of 10 to 120 min.

2. The preparation method according to claim 1, characterized in that During the preparation of the powder A, the grinding balls used in the ball milling process are ZrO2 grinding balls; the ball-to-material ratio is 1-3:1, the ball milling speed is 90-400 r / min, and the ball milling time is 4-24 h.

3. The preparation method according to claim 1, characterized in that During the preparation of the powder S, the powder A is transferred into a graphite mold, and then placed in a hot pressing sintering furnace or a spark plasma sintering furnace for solid solution under vacuum or protective atmosphere.

4. The preparation method according to claim 3, characterized in that The solid solution product is crushed and passed through a 100-300 mesh sieve to obtain the powder S.

5. The preparation method according to claim 1, characterized in that During the preparation of the powder Y, the grinding balls used in the ball milling process are ZrO2 grinding balls; the ball-to-material ratio is 1-3:1, the ball milling speed is 90-400 r / min, and the ball milling time is 4-24 h.

6. The preparation method according to claim 1, characterized in that During the preparation of the powder Y, the powder Y is transferred into a graphite mold, and then placed in a hot pressing sintering furnace or a spark plasma sintering furnace for in-situ reaction sintering under vacuum or a protective atmosphere.

7. The preparation method according to claim 1, characterized in that The chemical reactions that occur during in-situ reaction sintering are: 2(V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )Si2+B4C+3C→2(V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B2+4SiC。

Images