A method for preparing an ultrahigh-temperature ceramic material

Abstract

The application relates to the technical field of ultra-high-temperature ceramic materials, in particular to a preparation method of an ultra-high-temperature ceramic material, which comprises the following steps: uniformly mixing silicon-yttrium alloy powder I, zirconium boride and graphite to obtain initial powder; under an inert atmosphere, performing ball milling treatment on the initial powder, then performing forming processing to prepare ceramic green body material; and performing reaction melt impregnation on the ceramic green body material and silicon-yttrium alloy powder II at 1200-1500 DEG C to obtain ZrB2-YSi2-SiC ultra-high-temperature ceramic material. The application adopts the method of reaction melt impregnation to prepare high-density ultra-high-temperature ceramic material; under a high-temperature service environment, the binary-doped modified ZrB2 ceramic forms a dense oxide layer under high-temperature oxidation conditions, so as to improve the anti-oxidation corrosion performance of the material.

Description

Technical Field

[0001] This invention relates to the field of ultra-high temperature ceramic materials technology, and specifically to a method for preparing ultra-high temperature ceramic materials. Background Technology

[0002] Ultra-high temperature ceramics, abbreviated as UHTCs, generally refer to metallic materials used at temperatures above 1000℃. They are mainly composed of carbides, borides, nitrides, and oxides of transition metal compounds. These materials typically have melting points above 3000K and exhibit excellent high-temperature resistance and chemical stability. For example, ZrB2 has advantages such as a high melting point (3050℃), low cost, high hardness, and high chemical stability, and its density is only 6.1 g / cm³. 3 The coefficient of thermal expansion is 6.6 × 10⁻⁶. -6 With a modulus of 350 GPa and a strength of 6K, these excellent properties make it an ideal candidate material for ultra-high temperature thermal structural components.

[0003] Current ultra-high temperature ceramic material preparation technologies generally produce materials with low density, high porosity, low fracture toughness, poor thermal shock resistance, and poor oxidation resistance when used alone. Therefore, these challenges need to be addressed to advance ultra-high temperature ceramic materials for engineering applications. The primary challenge in ultra-high temperature ceramic material preparation is achieving densification. Current sintering methods are cumbersome, costly, and produce materials with high density, but this still presents difficulties in forming large and complex components. Furthermore, improving the oxidation resistance of ultra-high temperature ceramics under high-temperature conditions is also a major challenge.

[0004] Based on this, the present invention proposes a method for preparing ultra-high temperature ceramic materials, which can improve the density of ultra-high temperature ceramic materials while achieving the oxidation and corrosion resistance of materials under high temperature service environment, thus meeting the requirements for long service life. Summary of the Invention

[0005] To address the problems of high porosity, low surface density, and poor oxidation resistance under high-temperature conditions in existing ZrB2 ultra-high temperature ceramic materials, the present invention aims to provide a method for preparing ZrB2-YSi2-SiC ultra-high temperature ceramic materials. This method improves the density of ultra-high temperature ceramic materials while also achieving oxidation and corrosion resistance under high-temperature service conditions, thus meeting the requirements for long service life.

[0006] This invention employs reactive melt infiltration (RMI) to prepare highly dense ZrB2-YSi2-SiC ultra-high temperature ceramic materials. Under high-temperature service conditions, the binary doped modified ZrB2 ceramics form a dense oxide layer under high-temperature oxidation conditions, thereby improving the material's resistance to oxidation and corrosion.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows.

[0008] This invention provides a method for preparing ultra-high temperature ceramic materials, comprising the following steps:

[0009] Yttrium silicon alloy powder I was uniformly mixed with zirconium boride and graphite to obtain the initial powder;

[0010] Under an inert atmosphere, the initial powder is ball-milled and then shaped to obtain ceramic green body material;

[0011] Ultra-high temperature ceramic materials are obtained by reacting and infiltrating ceramic green materials with silicon-yttrium alloy powder II at 1200-1500℃.

[0012] In a preferred embodiment, yttrium silicon alloy powder I and yttrium silicon alloy powder II have the same composition, both being yttrium silicon alloy powders obtained by mixing Si and YSi2, wherein YSi2 accounts for 18% of the atomic percentage of the yttrium silicon alloy powder. YSi2 is commercially available yttrium disilicide; Si is commercially available elemental silicon.

[0013] In a preferred embodiment, graphite accounts for 10-30% of the weight of the initial powder;

[0014] The silicon-yttrium alloy powder I accounts for ≤20% of the weight of the initial powder.

[0015] In a preferred embodiment, the mass ratio of zirconium boride to yttrium silicon alloy powder I is 3:1.

[0016] In a preferred embodiment, the mass ratio of zirconium boride to graphite is 3:1 to 1.7.

[0017] In a preferred embodiment, the temperature of the reaction melt infiltration is 1300–1500°C, preferably 1300–1400°C, and more preferably 1400°C.

[0018] In a preferred embodiment, the infiltration time of the reactive melt is 15–120 min, preferably 30–90 min.

[0019] In a preferred embodiment, the particle size of yttrium silicon alloy powder I, zirconium boride, and graphite is 1–5 μm.

[0020] In a preferred embodiment, the powder purity of yttrium silicon alloy powder II, yttrium silicon alloy powder I, zirconium boride, and graphite is ≥99.9%.

[0021] In a preferred embodiment, the ball milling speed is 300-500 r / min and the ball milling time is 10-30 h.

[0022] In a preferred embodiment, the molding process is a molding process; the molding process is any one of dry pressing molding, isostatic pressing molding, and slip casting molding.

[0023] The beneficial effects of this invention are:

[0024] 1. This invention prepares a ceramic preform by using zirconium boride, graphite, and yttrium silicon alloy powder I. Then, the ceramic preform is subjected to reactive melt infiltration with yttrium silicon alloy powder II. During the infiltration process, graphite reacts with elemental silicon to generate SiC, thereby improving the density of the ultra-high temperature ceramic material and achieving the oxidation and corrosion resistance of the material under high temperature service environment, thus meeting the requirements for long service life.

[0025] 2. The method of the present invention has a lower preparation temperature and the preparation conditions are easier to meet. It can solve the problems of long preparation cycle and complex process of ZrB2-YSi2-SiC ultra-high temperature ceramic materials, and achieve high densification of ZrB2-YSi2-SiC ultra-high temperature ceramic materials.

[0026] 3. The method of the present invention has a short preparation time and simple process, and is suitable for the large-scale production of ultra-high temperature ceramic materials. It provides a new idea and process method for developing RMI process to prepare ZrB2-YSi2-SiC ultra-high temperature materials. Attached Figure Description

[0027] Figure 1 The image shows the cross-sectional morphology of the ultra-high temperature ceramic material prepared in Example 1.

[0028] Figure 2 Apparent density curves and open porosity curves of ultra-high temperature ceramic materials with different carbon contents prepared for Examples 1 and 5-9. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] ZrB2 has advantages such as a high melting point (3050℃), low cost, high hardness, and high chemical stability, and its density is only 6.1 g / cm³. 3 The coefficient of thermal expansion is 6.6 × 10⁻⁶. -6 With a high melting point (1300–2300 K) and an elastic modulus of 350 GPa, ZrB2 is an ideal candidate material for ultra-high temperature thermal structural components. While ZrB2 ultra-high temperature ceramics possess high melting point, high thermal conductivity, and good oxidation resistance, they still undergo oxidation in high-temperature aerobic environments, resulting in poor sintering performance. This is mainly because the ZrB2 surface oxidizes during high-temperature oxidation, forming white ZrO2 and glassy B2O3 oxide impurities, hindering the diffusion and migration between ZrB2 particles. Furthermore, as the sintering temperature increases, B2O3 volatilizes, and when the volatilization rate is much higher than its formation rate, a loose and porous ZrO2 structure is formed, which cannot prevent oxygen diffusion into the material, leading to material failure.

[0032] F. Monteverde et al. modified ZrB2 ultra-high temperature ceramics by adding SiC. They found that during sintering and oxidation, a SiO2 protective layer forms on the ZrB2 surface, which not only prevents the diffusion of internal oxidation products but also blocks external oxygen from entering the material. However, when the oxidation temperature is below 1000℃, the oxidation rate of SiC is relatively slow, and a sufficient SiO2 protective layer cannot be formed. The material surface still has some porosity, allowing external oxygen to enter the material and undergo oxidation, thus affecting the material's performance. Furthermore, as the oxidation temperature increases, SiC is oxidized to form SiO and CO gases, and the oxide layer on the material surface transforms into a porous structure, severely reducing the durability of ZrB2-SiC ultra-high temperature ceramics.

[0033] Furthermore, ZrB2-SiC ultra-high temperature ceramic materials prepared by existing sintering processes still exhibit high porosity and low surface density, affecting their performance. Therefore, addressing the problems of high porosity, low surface density, and poor oxidation resistance under high-temperature conditions in existing ZrB2 ultra-high temperature ceramic materials, this invention proposes a method for preparing ultra-high temperature ceramic materials. This method improves the density of the ultra-high temperature ceramic material while also achieving good oxidation and corrosion resistance under high-temperature service conditions, meeting the requirements for long service life.

[0034] This invention prepares ceramic green bodies using zirconium boride, graphite, and a yttrium silicon alloy. The ceramic green bodies are then subjected to a reactive melt infiltration process with the yttrium silicon alloy powder. During this infiltration, graphite reacts with elemental silicon to form SiC, thereby increasing the density of the ultra-high temperature ceramic material. This enhances the material's resistance to oxidation and corrosion under high-temperature service conditions, meeting the requirements for long service life. The ZrB2-YSi2-SiC ceramic material prepared by this method is highly dense and contains a high amount of rare earth elements, effectively improving its resistance to oxidation and corrosion.

[0035] The preparation process of the ultra-high temperature ceramic material provided by the present invention will be described in detail below.

[0036] This invention provides a method for preparing ultra-high temperature ceramic materials, comprising the following steps:

[0037] Yttrium silicon alloy powder I was uniformly mixed with zirconium boride and graphite to obtain the initial powder;

[0038] Under an inert atmosphere, the initial powder is ball-milled and then shaped to obtain ceramic green body material;

[0039] Ultra-high temperature ceramic materials are obtained by reacting and infiltrating ceramic green materials with silicon-yttrium alloy powder II at 1200-1500℃.

[0040] In a preferred embodiment, yttrium silicon alloy powder I and yttrium silicon alloy powder II have the same composition, both being yttrium silicon alloy powders obtained by mixing Si and YSi2, wherein YSi2 accounts for 18% of the atomic percentage of the yttrium silicon alloy powder. YSi2 is commercially available yttrium disilicide; Si is commercially available elemental silicon.

[0041] In a preferred embodiment, graphite constitutes 10-30% of the initial powder by weight; for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc.

[0042] The silicon-yttrium alloy powder I accounts for ≤20% of the weight of the initial powder. For example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.

[0043] In a preferred embodiment, the mass ratio of zirconium boride to yttrium silicon alloy powder I is 3:1.

[0044] In a preferred embodiment, the mass ratio of zirconium boride to graphite is 3:1 to 1.7. That is, the mass ratio of zirconium boride, graphite, and yttrium silicon alloy powder I is 3:1 to 1.7:1. Examples include 3:1:1, 3:1.1:1, 3:1.2:1, 3:1.3:1, 3:1.4:1, 3:1.5:1, 3:1.6:1, and 3:1.7:1.

[0045] In a preferred embodiment, the temperature for infiltrating the reactive melt is 1200–1500°C, more preferably 1300–1500°C, even more preferably 1300–1400°C, and even more preferably 1400°C. Examples include 1200°C, 1250°C, 1300°C, 1350°C, 1400°C, 1450°C, and 1500°C.

[0046] In a preferred embodiment, the infiltration time of the reaction melt is 15–120 min, preferably 30–90 min. Examples include 15 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, and 120 min.

[0047] In a preferred embodiment, the particle size of yttrium silicon alloy powder I, zirconium boride, and graphite is 1–5 μm.

[0048] In a preferred embodiment, the powder purity of yttrium silicon alloy powder II, yttrium silicon alloy powder I, zirconium boride, and graphite is ≥99.9%.

[0049] In a preferred embodiment, the ball milling speed is 300-500 r / min, for example, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, etc.

[0050] The ball milling time is 10 to 30 hours. For example, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, and 30 hours.

[0051] In a preferred embodiment, the molding process is performed using a molding process; the molding process is any one of dry pressing molding, isostatic pressing molding, and slurry injection molding.

[0052] In a preferred embodiment, the dry pressing process involves dry pressing the mixed ceramic powder at a pressure of 10 MPa for a holding time of 120–180 s. Examples include 120 s, 130 s, 140 s, 150 s, 160 s, 170 s, and 180 s.

[0053] In a preferred embodiment, the isostatic pressing process involves isostatically pressing mixed ceramic powder at a pressure of 10 MPa for a holding time of 120–180 s. Examples include 120 s, 130 s, 140 s, 150 s, 160 s, 170 s, and 180 s.

[0054] In a preferred embodiment, the grouting process involves preparing a slurry from mixed ceramic powder, pressing the slurry into a high-strength, permeable mold for grouting, with a pressure of 10 MPa and a holding time of 120–180 seconds. Examples include 120 seconds, 130 seconds, 140 seconds, 150 seconds, 160 seconds, 170 seconds, and 180 seconds. Specific Implementation

[0056] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0057] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0058] In various embodiments of the present invention, RMI stands for reactive melt infiltration.

[0059] Unless otherwise specified, the methods described in the following embodiments are conventional methods; the reagents and materials mentioned are commercially available unless otherwise specified.

[0060] In the following embodiments, yttrium silicon alloy powder I and yttrium silicon alloy powder II have the same composition, both being yttrium silicon alloy powders obtained by mixing Si and YSi2, wherein YSi2 accounts for 18% of the atomic percentage of the yttrium silicon alloy powder. YSi2 is commercially available yttrium disilicide; Si is commercially available elemental silicon.

[0061] Example 1

[0062] A method for preparing ultra-high temperature ceramic materials includes the following steps:

[0063] Step 1. Preparation of mixed ceramic powders:

[0064] Zirconium boride, graphite, and yttrium silicon alloy powder I were uniformly mixed at a weight ratio of 3:1:1 to obtain an initial powder. The initial powder and steel balls in the grinding jar were placed in a grinding jar, and anhydrous ethanol was added to obtain a slurry. The grinding jar was evacuated. An inert gas was introduced into the grinding jar. The slurry was subjected to high-energy ball milling using a planetary ball mill. The high-energy ball-milled slurry was dried to obtain a mixed ceramic powder.

[0065] Step 2. Ceramic molding:

[0066] Weigh 1g of the mixed ceramic powder as needed, place it into a pressing mold with dimensions of Φ12.7mm×3mm, and use a pressing machine to press it into a sheet at a pressure of 10MPa for 180s to obtain the ceramic green body material.

[0067] Step 3. Introducing silicon-yttrium alloy using reactive melt infiltration:

[0068] The prepared ceramic green material and silicon-yttrium alloy powder II were placed in a graphite crucible and then placed in a melting furnace. The reaction solution infiltration process was carried out in a vacuum environment, with a holding temperature of 1300℃ and a holding time of 60min, thereby completing the melting infiltration preparation process of ZrB2-YSi2-SiC sample and preparing ZrB2-YSi2-SiC ultra-high temperature ceramic material with a melting infiltration temperature of 1300℃.

[0069] Example 2

[0070] A method for preparing ultra-high temperature ceramic materials includes the following steps:

[0071] Step 1. Preparation of mixed ceramic powders:

[0072] Zirconium boride, graphite, and yttrium silicon alloy powder I were uniformly mixed at a weight ratio of 3:1:1 to obtain an initial powder. The initial powder and steel balls in the grinding jar were placed in a grinding jar, and anhydrous ethanol was added to obtain a slurry. The grinding jar was evacuated. An inert gas was introduced into the grinding jar. The slurry was subjected to high-energy ball milling using a planetary ball mill. The high-energy ball-milled slurry was dried to obtain a mixed ceramic powder.

[0073] Step 2. Ceramic molding:

[0074] Weigh 1g of the mixed ceramic powder as needed, place it into a pressing mold with dimensions of Φ12.7mm×3mm, and use a pressing machine to press it into a sheet at a pressure of 10MPa for 180s to obtain the ceramic green body material.

[0075] Step 3. Introducing silicon-yttrium alloy using reactive melt infiltration:

[0076] The prepared ceramic green material and silicon-yttrium alloy powder II were placed in a graphite crucible and then placed in a melting furnace. The reaction solution infiltration process was carried out in a vacuum environment, with a holding temperature of 1400℃ and a holding time of 60 min. This completed the melting infiltration preparation process of the ZrB2-YSi2-SiC sample, and ZrB2-YSi2-SiC ultra-high temperature ceramic material with a melting infiltration temperature of 1400℃ was prepared.

[0077] Example 3

[0078] A method for preparing ultra-high temperature ceramic materials includes the following steps:

[0079] Step 1. Preparation of mixed ceramic powders:

[0080] Zirconium boride, graphite, and yttrium silicon alloy powder I were uniformly mixed at a weight ratio of 3:1:1 to obtain an initial powder. The initial powder and steel balls were placed in a ball milling jar, and anhydrous ethanol was added to obtain a slurry. The ball milling jar was evacuated. An inert gas was introduced into the ball milling jar. The slurry was subjected to high-energy ball milling using a planetary ball mill. The high-energy ball-milled slurry was dried to obtain a mixed ceramic powder.

[0081] Step 2. Ceramic molding:

[0082] Weigh 1g of the mixed ceramic powder as needed, place it into a pressing mold with dimensions of Φ12.7mm×3mm, and use a pressing machine to press it into a sheet at a pressure of 10MPa for 180s to obtain the ceramic green body material.

[0083] Step 3. Introducing silicon-yttrium alloy using reactive melt infiltration:

[0084] The prepared ceramic green material and silicon-yttrium alloy powder II were placed in a graphite crucible and then placed in a melting furnace. The reaction solution infiltration process was carried out in a vacuum environment, with a holding temperature of 1500℃ and a holding time of 60min, thereby completing the melting infiltration preparation process of ZrB2-YSi2-SiC sample and preparing ZrB2-YSi2-SiC ultra-high temperature ceramic material with a melting infiltration temperature of 1500℃.

[0085] Example 4

[0086] A method for preparing ultra-high temperature ceramic materials includes the following steps:

[0087] Step 1. Preparation of mixed ceramic powders:

[0088] Zirconium boride, graphite, and yttrium silicon alloy powder I were uniformly mixed at a weight ratio of 3:1:1 to obtain an initial powder. The initial powder and steel balls were placed in a ball milling jar, and anhydrous ethanol was added to obtain a slurry. The ball milling jar was evacuated. An inert gas was introduced into the ball milling jar. The slurry was subjected to high-energy ball milling using a planetary ball mill. The high-energy ball-milled slurry was dried to obtain a mixed ceramic powder.

[0089] Step 2. Ceramic molding:

[0090] Weigh 1g of the mixed ceramic powder as needed, place it into a pressing mold with dimensions of Φ12.7mm×3mm, and use a pressing machine to press it into a sheet at a pressure of 10MPa for 180s to obtain the ceramic green body material.

[0091] Step 3. Introducing silicon-yttrium alloy using reactive melt infiltration:

[0092] The prepared ceramic green material and silicon-yttrium alloy powder II were placed in a graphite crucible and then placed in a melting furnace. The reaction solution infiltration process was carried out in a vacuum environment, with a holding temperature of 1200℃ and a holding time of 60min, thereby completing the melting infiltration preparation process of ZrB2-YSi2-SiC sample and preparing ZrB2-YSi2-SiC ultra-high temperature ceramic material with a melting infiltration temperature of 1200℃.

[0093] Example 5

[0094] A method for preparing ultra-high temperature ceramic materials includes the following steps:

[0095] Step 1. Preparation of mixed ceramic powders:

[0096] Weigh the raw material powders according to the preset ratio: by weight percentage, zirconium boride 80%, graphite 5%, and yttrium silicon alloy 15%.

[0097] Zirconium boride, graphite, and yttrium silicon alloy powder I are uniformly mixed in a preset ratio to obtain an initial powder. The initial powder and steel balls in the grinding jar are placed in a grinding jar, and anhydrous ethanol is added to obtain a slurry. The grinding jar is evacuated. An inert gas is introduced into the grinding jar. The slurry is subjected to high-energy ball milling using a planetary ball mill. The high-energy ball-milled slurry is dried to obtain a mixed ceramic powder.

[0098] Step 2. Ceramic molding:

[0099] Weigh 1g of the mixed ceramic powder as needed, place it into a pressing mold with dimensions of Φ12.7mm×3mm, and use a pressing machine to press it into a sheet at a pressure of 10MPa for 180s to obtain the ceramic green body material.

[0100] Step 3. Introducing silicon-yttrium alloy using reactive melt infiltration:

[0101] The prepared ceramic green material and silicon-yttrium alloy powder II were placed in a graphite crucible and then placed in a melting furnace. The reaction solution infiltration process was carried out in a vacuum environment, with a holding temperature of 1300℃ and a holding time of 60min, thereby completing the melting infiltration preparation process of ZrB2-YSi2-SiC sample and preparing ZrB2-YSi2-SiC ultra-high temperature ceramic material with a melting infiltration temperature of 1300℃.

[0102] Example 6

[0103] A method for preparing ultra-high temperature ceramic materials includes the following steps:

[0104] Step 1. Preparation of mixed ceramic powders:

[0105] Weigh the raw material powders according to the preset ratio: by weight percentage, zirconium boride 70%, graphite 15%, and yttrium silicon alloy 15%.

[0106] Zirconium boride, graphite, and yttrium silicon alloy powder I are uniformly mixed in a preset ratio to obtain an initial powder. The initial powder and steel balls in the grinding jar are placed in a grinding jar, and anhydrous ethanol is added to obtain a slurry. The grinding jar is evacuated. An inert gas is introduced into the grinding jar. The slurry is subjected to high-energy ball milling using a planetary ball mill. The high-energy ball-milled slurry is dried to obtain a mixed ceramic powder.

[0107] Step 2. Ceramic molding:

[0108] Weigh 1g of the mixed ceramic powder as needed, place it into a pressing mold with dimensions of Φ12.7mm×3mm, and use a pressing machine to press it into a sheet at a pressure of 10MPa for 180s to obtain the ceramic green body material.

[0109] Step 3. Introducing silicon-yttrium alloy using reactive melt infiltration:

[0110] The prepared ceramic green material and silicon-yttrium alloy powder II were placed in a graphite crucible and then placed in a melting furnace. The reaction solution infiltration process was carried out in a vacuum environment, with a holding temperature of 1300℃ and a holding time of 60min, thereby completing the melting infiltration preparation process of ZrB2-YSi2-SiC sample and preparing ZrB2-YSi2-SiC ultra-high temperature ceramic material with a melting infiltration temperature of 1300℃.

[0111] Example 7

[0112] A method for preparing ultra-high temperature ceramic materials includes the following steps:

[0113] Step 1. Preparation of mixed ceramic powders:

[0114] Weigh the raw material powders according to the preset ratio: by weight percentage, zirconium boride 60%, graphite 25%, and yttrium silicon alloy 15%.

[0115] Zirconium boride, graphite, and yttrium silicon alloy powder I are uniformly mixed in a preset ratio to obtain an initial powder. The initial powder and steel balls in the grinding jar are placed in a grinding jar, and anhydrous ethanol is added to obtain a slurry. The grinding jar is evacuated. An inert gas is introduced into the grinding jar. The slurry is subjected to high-energy ball milling using a planetary ball mill. The high-energy ball-milled slurry is dried to obtain a mixed ceramic powder.

[0116] Step 2. Ceramic molding:

[0117] Weigh 1g of the mixed ceramic powder as needed, place it into a pressing mold with dimensions of Φ12.7mm×3mm, and use a pressing machine to press it into a sheet at a pressure of 10MPa for 180s to obtain the ceramic green body material.

[0118] Step 3. Introducing silicon-yttrium alloy using reactive melt infiltration:

[0119] The prepared ceramic green material and silicon-yttrium alloy powder II were placed in a graphite crucible and then placed in a melting furnace. The reaction solution infiltration process was carried out in a vacuum environment, with a holding temperature of 1300℃ and a holding time of 60min, thereby completing the melting infiltration preparation process of ZrB2-YSi2-SiC sample and preparing ZrB2-YSi2-SiC ultra-high temperature ceramic material with a melting infiltration temperature of 1300℃.

[0120] Example 8

[0121] A method for preparing ultra-high temperature ceramic materials includes the following steps:

[0122] Step 1. Preparation of mixed ceramic powders:

[0123] Weigh the raw material powders according to the preset ratio: by weight percentage, zirconium boride 50%, graphite 35%, and yttrium silicon alloy 15%.

[0124] Zirconium boride, graphite, and yttrium silicon alloy powder I are uniformly mixed in a preset ratio to obtain an initial powder. The initial powder and steel balls in the grinding jar are placed in a grinding jar, and anhydrous ethanol is added to obtain a slurry. The grinding jar is evacuated. An inert gas is introduced into the grinding jar. The slurry is subjected to high-energy ball milling using a planetary ball mill. The high-energy ball-milled slurry is dried to obtain a mixed ceramic powder.

[0125] Step 2. Ceramic molding:

[0126] Weigh 1g of the mixed ceramic powder as needed, place it into a pressing mold with dimensions of Φ12.7mm×3mm, and use a pressing machine to press it into a sheet at a pressure of 10MPa for 180s to obtain the ceramic green body material.

[0127] Step 3. Introducing silicon-yttrium alloy using reactive melt infiltration:

[0128] The prepared ceramic green material and silicon-yttrium alloy powder II were placed in a graphite crucible and then placed in a melting furnace. The reaction solution infiltration process was carried out in a vacuum environment, with a holding temperature of 1300℃ and a holding time of 60min, thereby completing the melting infiltration preparation process of ZrB2-YSi2-SiC sample and preparing ZrB2-YSi2-SiC ultra-high temperature ceramic material with a melting infiltration temperature of 1300℃.

[0129] Example 9

[0130] A method for preparing ultra-high temperature ceramic materials includes the following steps:

[0131] Step 1. Preparation of mixed ceramic powders:

[0132] Weigh the raw material powders according to the preset ratio: by weight percentage, zirconium boride 40%, graphite 45%, and yttrium silicon alloy 15%.

[0133] Zirconium boride, graphite, and yttrium silicon alloy powder I are uniformly mixed in a preset ratio to obtain an initial powder. The initial powder and steel balls in the grinding jar are placed in a grinding jar, and anhydrous ethanol is added to obtain a slurry. The grinding jar is evacuated. An inert gas is introduced into the grinding jar. The slurry is subjected to high-energy ball milling using a planetary ball mill. The high-energy ball-milled slurry is dried to obtain a mixed ceramic powder.

[0134] Step 2. Ceramic molding:

[0135] Weigh 1g of the mixed ceramic powder as needed, place it into a pressing mold with dimensions of Φ12.7mm×3mm, and use a pressing machine to press it into a sheet at a pressure of 10MPa for 180s to obtain the ceramic green body material.

[0136] Step 3. Introducing silicon-yttrium alloy using reactive melt infiltration:

[0137] The prepared ceramic green material and silicon-yttrium alloy powder II were placed in a graphite crucible and then placed in a melting furnace. The reaction solution infiltration process was carried out in a vacuum environment, with a holding temperature of 1300℃ and a holding time of 60min, thereby completing the melting infiltration preparation process of ZrB2-YSi2-SiC sample and preparing ZrB2-YSi2-SiC ultra-high temperature ceramic material with a melting infiltration temperature of 1300℃.

[0138] The performance of the ultra-high temperature ceramic materials prepared in the above embodiments was tested.

[0139] Test Example 1: Cross-sectional Micromorphology Analysis

[0140] The ultra-high temperature ceramic material prepared in Example 1 was cross-sectioned, and the cross-section was observed and analyzed at high magnification using a scanning electron microscope. The microstructure of the cross-section is shown below. Figure 1 As shown. Figure 1 The image shows the cross-sectional morphology of the ultra-high temperature ceramic material prepared in Example 1.

[0141] exist Figure 1 In the surface microstructure diagram, the gray particles are ZrB2 particles; the black particles are graphite carbon; and the white particles are Y elements. Figure 1 As can be seen, a small portion of the graphite carbon agglomerates and is not consumed; the mixed phase of ZrB2 and YSi2 is uniformly dispersed internally.

[0142] Test Example 2: The effect of different melting and infiltration temperatures on the performance of ultra-high temperature ceramic materials.

[0143] The apparent density and open porosity of the ultra-high temperature ceramic materials prepared at different melting and infiltration temperatures in Examples 1 to 4 were tested as samples to be tested. The results are shown in Tables 1 and 2.

[0144] Table 1. Feeding conditions at different melting temperatures

[0145] Example <![CDATA[Weight ratio a > Melting temperature (°C) sample 1 3:1:1 1300 ZSY-1 2 3:1:1 1400 ZSY-2 3 3:1:1 1500 ZSY-3 4 3:1:1 1200 ZSY-4

[0146] Note: weight ratio a The weight ratio of zirconium boride, graphite, and yttrium silicon alloy powder I is given. The sample is an ultra-high temperature ceramic material prepared by melt infiltration.

[0147] Table 2. Effects of different melting temperatures on the properties of ultra-high temperature ceramic materials

[0148] Example sample <![CDATA[Apparent density (g / cm 3 )]]> Porosity (%) 1 ZSY-1 4.09 0.43 2 ZSY-2 4.15 0.25 3 ZSY-3 3.95 1.03 4 ZSY-4 3.14 10.17

[0149] As shown in Tables 1 and 2, with increasing melting temperature, the apparent density of the samples first increases and then decreases, while the open porosity first decreases and then increases. Furthermore, the apparent density reaches its highest value of 4.15 g / cm³ at a melting temperature of 1400℃. 3 The sample's open porosity reached a minimum of 0.25%. This indicates that at temperatures of 1300–1400℃, both the sample's apparent density and open porosity meet the process requirements.

[0150] Test Example 3: The effect of different amounts of graphite on the performance of ultra-high temperature ceramic materials.

[0151] The apparent density and open porosity of ultra-high temperature ceramic materials prepared with different amounts of graphite in Examples 5-9 were tested. The feeding conditions for different amounts of graphite are shown in Table 3, and the test results are as follows: Figure 1 As shown.

[0152] Figure 2 Apparent density curves and open porosity curves of ultra-high temperature ceramic materials with different carbon contents prepared in Examples 5-9.

[0153] Table 3. Feeding conditions for different graphite addition amounts

[0154]

[0155] Table 4. Effects of different graphite addition amounts on the properties of ultra-high temperature ceramic materials.

[0156] Example serial number <![CDATA[Apparent density (g / cm 3 )]]> Porosity (%) 5 Z-1 4.25 1.99 6 Z-2 4.35 0.01 7 Z-3 3.80 0.17 8 Z-4 3.40 1.12 9 Z-5 2.93 1.76

[0157] From Table 4 and Figure 2 The results clearly show that the ZrB2-YSi2-SiC ultra-high temperature ceramic material prepared by the RMI process has good density, with an overall open porosity of no more than 2%. With adjustments to the graphite carbon content, the apparent density curve generally shows an initial increase followed by a decrease, while the open porosity curve shows an initial decrease followed by an increase. This is mainly because the addition of graphite carbon consumes the elemental silicon introduced during the melting and infiltration process, causing it to generate SiC in the melting and infiltration reaction, thereby increasing the material's density and achieving the required oxidation and corrosion resistance under high-temperature service conditions, thus meeting the requirements for long service life. In contrast, ultra-high temperature ceramic materials prepared by existing technologies generally have a porosity of over 10% and lower density. Compared with ultra-high temperature ceramic materials prepared by existing technologies, Figure 2 All samples exhibited good density and low porosity, meeting the density requirements of ultra-high temperature ceramic materials. However, considering the microstructure and phase composition of the materials, the composition of sample Z-2 was the optimal ratio.

[0158] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an ultra-high temperature ceramic material, characterized in that, Includes the following steps: Yttrium silicon alloy powder I was uniformly mixed with zirconium boride and graphite to obtain the initial powder; Under an inert atmosphere, the initial powder is ball-milled and then shaped to obtain ceramic green body material; The ceramic green material was subjected to reactive melt infiltration with silicon yttrium alloy powder II at 1300℃~1500℃ for 60min~120min to obtain ultra-high temperature ceramic material. Yttrium silicon alloy powder I and Yttrium silicon alloy powder II have the same composition, both being Yttrium silicon alloy powders obtained by mixing Si and YSi2, wherein YSi2 accounts for 18% of the atomic percentage of the Yttrium silicon alloy powder; The graphite constitutes 10% to 30% of the initial powder by weight; The silicon-yttrium alloy powder I accounts for ≤20% of the weight of the initial powder.

2. The method for preparing ultra-high temperature ceramic materials according to claim 1, characterized in that, The mass ratio of zirconium boride to yttrium silicon alloy powder I is 3:

1.

3. The method for preparing ultra-high temperature ceramic materials according to claim 2, characterized in that, The mass ratio of zirconium boride to graphite is 3:1 to 1.

7.

4. The method for preparing ultra-high temperature ceramic materials according to claim 1, characterized in that, The particle size of silicon-yttrium alloy powder I, zirconium boride, and graphite is 1μm~5μm.

5. The method for preparing ultra-high temperature ceramic materials according to claim 1, characterized in that, The purity of yttrium silicon alloy powder II, yttrium silicon alloy powder I, zirconium boride, and graphite is ≥99.9%.

6. The method for preparing ultra-high temperature ceramic materials according to claim 1, characterized in that, The molding process is a molding process; the molding process is any one of dry pressing molding process, isostatic pressing molding process, and slip casting molding process.

Images