An ultra-high temperature ceramic with long-time ablation resistance and toughness and a preparation method thereof
By introducing silicon carbide whiskers and rare earth element compounds into HfC-ZrC ultra-high temperature ceramics, ceramic materials with excellent toughness and ablation resistance were prepared, solving the problem of toughness and ablation resistance of ceramic materials at high temperatures, achieving efficient long-term ablation resistance, and simplifying the preparation process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XI AN JIAOTONG UNIV
- Filing Date
- 2024-04-22
- Publication Date
- 2026-06-19
Smart Images
Figure CN118388255B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ultra-high temperature ceramic materials, specifically to an ultra-high temperature ceramic that combines resistance to long-term ablation and toughness, and its preparation method. Background Technology
[0002] In recent years, with the rapid development of aerospace and other fields, the leading edge and tip of hypersonic vehicles face more extreme thermal convection and radiation, with surface temperatures reaching over 2400℃. Traditional high-temperature alloys were the earliest ultra-high-temperature materials used, possessing excellent plasticity and toughness and easy processing, but they have high density and poor resistance to high-temperature oxidation, and their application temperature is generally below 1200℃. Carbon-based composite materials have excellent thermomechanical properties, with high specific strength and specific modulus, but their oxidation resistance is poor. The long-term application temperature of C / SiC composite materials is generally below 1650℃, and uncoated C / C composite materials begin to oxidize rapidly above 500℃. This indicates that traditional thermal protection material systems can no longer meet the requirements of hypersonic vehicles.
[0003] Ultra-high temperature ceramics refer to a class of ceramic materials that are chemically stable at ultra-high temperatures (above 2000℃) and in oxygen-containing atmospheres. They typically include borides, carbides, and nitrides of refractory transition metals, as well as other high-melting-point compounds. Among ultra-high temperature ceramic material systems, hafnium carbide and zirconium carbide have melting points as high as 3900℃ and 3500℃, respectively, while their oxides, hafnium dioxide (HfO2) and zirconium dioxide (ZrO2), also have melting points as high as 2800℃ and 2700℃, respectively, demonstrating the potential to withstand prolonged ablation at ultra-high temperatures.
[0004] The ultra-high temperature ablation process involves two processes: first, the matrix oxidation process occurring in an aerobic environment; and second, the shearing and mechanical exfoliation process caused by high-speed airflow. These two processes act simultaneously on the surface of the ablated material. Matrix oxidation increases the material's mass and thickness, while the exfoliation and pitting of the surface oxide layer decreases its mass and thickness. Therefore, the mass ablation rate and linear ablation rate are jointly determined by these two processes. Currently, methods to improve the ablation resistance of ceramics include: First, introducing borides, silicides, oxides, etc., to prepare multiphase composite ceramics. During ablation, liquid oxides are generated, improving the viscosity of the oxide layer and strengthening interatomic chemical bonds, thus enhancing the material's ablation resistance. Second, introducing reinforcing phases such as fibers and particles to improve the ceramic's thermal shock resistance and shear erosion resistance, resulting in composite materials with excellent mechanical properties at high temperatures and good high-temperature damage tolerance.
[0005] Currently, the main method to improve the ablation resistance of HfC-ZrC ultra-high temperature ceramics is to introduce a low-melting-point glassy phase. Some researchers have introduced titanium carbide (TiC), which forms a low-melting-point TiO2 phase during ablation. At high temperatures, TiO2 can flow and fill defects such as cracks and pores, acting as a sealant. However, at 2100℃ for 120 seconds, the oxide layer begins to peel off, making it difficult to withstand the requirements of long-term ablation at higher temperatures. Some studies have proposed improving fracture toughness by introducing carbon fibers or silicon carbide fibers to prepare continuous fiber-reinforced ceramic matrix composites. However, this method requires sophisticated equipment, is costly, time-consuming, and involves complex fabrication processes. Furthermore, ultra-high temperature ceramics possess intrinsic brittleness due to the presence of numerous ionic and covalent bonds in their chemical bonds, which significantly limits their use as ultra-high temperature structural materials in practical applications. Summary of the Invention
[0006] The purpose of this invention is to provide an ultra-high temperature ceramic with both long-term ablation resistance and toughness, and a method for preparing the same. The preparation process of this method is simple, and the ultra-high temperature ceramic prepared by this method has good long-term ablation resistance and excellent fracture toughness.
[0007] To achieve the above objectives, the technical solution of the present invention is a method for preparing ultra-high temperature ceramics that combine resistance to long-term ablation and toughness, comprising the following steps:
[0008] Step 1: Weigh 20-80 parts of hafnium carbide powder and 20-80 parts of zirconium carbide powder according to volume fractions, and mix them with 3-10% of silicon hexaboride powder, 5-20% of rare earth element compounds and 5-30% of silicon carbide whiskers, accounting for 3-10% of the total volume of the two powders, to obtain a mixed powder.
[0009] Step 2: Place the mixed powder into a ball mill jar and perform wet ball milling at a ball-to-material mass ratio of 3-8 to obtain a mixed powder solution;
[0010] Step 3: Perform preliminary drying of the mixed powder solution by rotary evaporation under vacuum until the liquid evaporates into block powder, and then continue vacuum drying until a completely dry uniform powder is obtained.
[0011] Step 4: Grind the dry, uniform powder and sieve it, then put it into a graphite mold. Place the graphite mold into a spark plasma sintering equipment, and heat it to 1750-1900℃ at a sintering pressure of 40-80MPa and a heating rate of 50-100℃ / min. Hold it at that temperature for 20-30min, and then cool it to room temperature to obtain rare earth element stabilized HfC-ZrC-SiCw ultra-high temperature ceramic.
[0012] Furthermore, the rare earth element compound in step one is one or more of lanthanum oxide, lanthanum boride, yttrium carbide, yttrium oxide, and yttrium boride.
[0013] Furthermore, in step two, the wet ball milling process involves adding anhydrous ethanol or isopropanol and ball milling at a speed of 200-500 r / min for 10-24 h.
[0014] Furthermore, in step three, the rotary evaporation drying speed is 10-20 r / min, and the temperature is 35-50℃.
[0015] Furthermore, the vacuum drying temperature in step three is 50-60℃.
[0016] Furthermore, in step four, the sieving process specifically involves passing the material through a 150-250 mesh sieve.
[0017] A high-temperature ceramic exhibiting both resistance to long-term ablation and high toughness, wherein the high-temperature ceramic has a uniform microstructure, a dense structure, and a fracture toughness greater than 5 MPa.m 1 / 2 It can withstand ablation for more than 600 seconds at 2500℃ in a plasma ablation system.
[0018] Compared with the prior art, the present invention has the following beneficial effects:
[0019] (1) The preparation method of the present invention uses silicon carbide whiskers as the second phase and adds rare earth element compounds. Compared with the preparation process of continuous fiber toughened ultra-high temperature ceramic matrix composites in the prior art, it does not require the repeated impregnation and deposition steps of precursor pyrolysis process PIP and chemical vapor deposition process. Ultra-high temperature ceramics with both long-term ablation resistance and toughness can be prepared by sintering. The preparation process is simple.
[0020] (2) The ultra-high temperature ceramic prepared by this invention uses HfC-ZrC ultra-high temperature ceramic as the matrix and adds silicon carbide whiskers. By promoting crack deflection, bridging, and whisker pull-out and load bearing, the fracture toughness of the ultra-high temperature ceramic is improved. During ablation, silicon carbide whiskers can be oxidized to generate silicon dioxide. As the temperature increases, a continuous glass phase-filled oxide layer can be formed, reducing the inward diffusion of oxygen atoms and the outward precipitation of metal atoms, improving the stability of the oxide layer, and improving the ablation resistance of HfC-ZrC ultra-high temperature ceramic. At the same time, rare earth element compounds are added. During the ablation process, rare earth elements can form solid solutions with the oxides of hafnium carbide and zirconium carbide, inhibiting the occurrence of phase transformation, stabilizing the oxide layer, reducing volume expansion, and reducing the thermal stress generated during the ablation process, thereby improving its ablation resistance. Furthermore, rare earth elements can work synergistically with silicon carbide whiskers to form a high-viscosity silicate compound oxide layer after ablation, which plays a synergistic role in enhancing the ablation resistance. Attached Figure Description
[0021] Figure 1 This is a SEM image of the mixed powder after wet ball milling during the preparation process of Example 1 of the present invention;
[0022] Figure 2 This is a SEM image of the ultra-high temperature ceramic prepared in Example 1 of the present invention;
[0023] Figure 3 This is a macroscopic morphology image of the ultra-high temperature ceramic prepared in Example 1 of the present invention after ablation at 2500℃ for 600s;
[0024] Figure 4 This is a SEM image of the surface oxide layer of the ultra-high temperature ceramic prepared in Example 1 of the present invention after ablation. Detailed Implementation
[0025] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.
[0026] Example 1: A method for preparing an ultra-high temperature ceramic that combines resistance to long-term ablation and toughness, comprising the following steps:
[0027] Step 1: Weigh 50 parts hafnium carbide powder and 50 parts zirconium carbide powder according to volume fractions, and mix them with 5% silicon hexaboride powder, 7% lanthanum oxide and 10% silicon carbide whiskers, which account for 5% of the total volume of the two powders, to obtain a mixed powder.
[0028] Step 2: Place the mixed powder into a ball mill jar, add anhydrous ethanol to the ball mill jar at a ball:material mass ratio of 5:1, and wet ball mill at a speed of 400 r / min for 12 h to obtain a mixed powder solution.
[0029] Step 3: The mixed powder solution is initially dried by rotary evaporation in a vacuum at a speed of 15 r / min and a temperature of 40°C until the liquid evaporates into block powder. Then, vacuum drying is continued at a temperature of 50°C until a completely dried uniform powder is obtained.
[0030] Step 4: Grind the dry, uniform powder and pass it through a 200-mesh sieve. Then, put the powder into a graphite mold and place the graphite mold into a spark plasma sintering equipment. Under a sintering pressure of 50 MPa, raise the temperature to 1800℃ at a heating rate of 50℃ / min and hold for 20 min. Then, cool it to room temperature to obtain rare earth element stabilized HfC-ZrC-SiCw ultra-high temperature ceramic. The fracture toughness was measured to be 5.48 MPa·m1 / 2 by indentation method.
[0031] like Figure 1 As shown, after wet ball milling, the powder obtained has uniform particle and whisker distribution, and the whiskers have a relatively complete shape.
[0032] like Figure 2As shown, the black phase is silicon carbide whiskers. After spark plasma sintering, the whiskers are evenly distributed and have a dense structure.
[0033] like Figure 3 As shown, it can be seen that after being ablated at 2500℃ for 600s under plasma flame, only a small amount of oxide layer peeled off the surface of the ultra-high temperature ceramic, and the overall structure is dense and the shape is intact.
[0034] like Figure 4 As shown, the microstructure of the oxide layer on the surface of the ultra-high temperature ceramic after ablation at 2500℃ for 600s is flat and dense, with only a few cracks. The phase transformation is suppressed by rare earth element compound La2O3 and the toughening is achieved by silicon carbide whiskers, which reduces thermal stress and improves ablation resistance.
[0035] Example 2: A method for preparing an ultra-high temperature ceramic that combines resistance to long-term ablation and toughness, comprising the following steps:
[0036] Step 1: Weigh 20 parts hafnium carbide powder and 60 parts zirconium carbide powder according to volume fractions, and mix them with 3% silicon hexaboride powder, 5% lanthanum boride and 5% silicon carbide whiskers, which account for 3% of the total volume of the two powders, to obtain a mixed powder.
[0037] Step 2: Place the mixed powder into a ball mill jar, add anhydrous ethanol to the ball mill jar at a ball:material mass ratio of 3:1, and wet ball mill at a speed of 200 r / min for 20 h to obtain a mixed powder solution.
[0038] Step 3: The mixed powder solution is initially dried by rotary evaporation in a vacuum at a speed of 15 r / min and a temperature of 40°C until the liquid evaporates into block powder. Then, vacuum drying is continued at a temperature of 55°C until a completely dried uniform powder is obtained.
[0039] Step 4: Grind the dry, uniform powder and pass it through a 180-mesh sieve. Then, put the powder into a graphite mold and place the graphite mold into a spark plasma sintering equipment. Under a sintering pressure of 60 MPa, raise the temperature to 1750°C at a heating / cooling rate of 70°C / min, hold for 30 min, and then cool to room temperature to obtain rare earth element stabilized HfC-ZrC-SiCw ultra-high temperature ceramic.
[0040] Example 3: A method for preparing an ultra-high temperature ceramic that combines resistance to long-term ablation and toughness, comprising the following steps:
[0041] Step 1: Weigh 80 parts hafnium carbide powder and 30 parts zirconium carbide powder according to volume fractions, and mix them with silicon hexaboride powder (7% of the total volume of the two powders), yttrium carbide powder (10%) and silicon carbide whiskers (8%) to obtain a mixed powder.
[0042] Step 2: Place the mixed powder into a ball mill jar, add isopropanol to the ball mill jar at a ball:material mass ratio of 8:1, and wet ball mill at a speed of 250 r / min for 10 h to obtain a mixed powder solution.
[0043] Step 3: The mixed powder solution is initially dried by rotary evaporation in a vacuum at a speed of 18 r / min and a temperature of 50°C until the liquid evaporates into block powder. Then, vacuum drying is continued at a temperature of 60°C until a completely dried uniform powder is obtained.
[0044] Step 4: Grind the dry, uniform powder and pass it through a 160-mesh sieve. Then, put the powder into a graphite mold and place the graphite mold into a spark plasma sintering equipment. Under a sintering pressure of 45 MPa, raise the temperature to 1780°C at a heating / cooling rate of 80°C / min, hold for 20 min, and then cool to room temperature to obtain rare earth element stabilized HfC-ZrC-SiCw ultra-high temperature ceramic.
[0045] Example 4: A method for preparing an ultra-high temperature ceramic that combines resistance to long-term ablation and toughness, comprising the following steps:
[0046] Step 1: Weigh 40 parts hafnium carbide powder and 20 parts zirconium carbide powder according to volume fractions, and mix them with silicon hexaboride powder (6% of the total volume of the two powders), yttrium oxide (15%) and silicon carbide whiskers (25%) to obtain a mixed powder.
[0047] Step 2: Place the mixed powder into a ball mill jar, add anhydrous ethanol to the ball mill jar at a ball:material mass ratio of 5:1, and wet ball mill at a speed of 300 r / min for 22 h to obtain a mixed powder solution.
[0048] Step 3: The mixed powder solution is initially dried by rotary evaporation in a vacuum at a speed of 20 r / min and a temperature of 35°C until the liquid evaporates into block powder. Then, vacuum drying is continued at a temperature of 58°C until a completely dried uniform powder is obtained.
[0049] Step 4: Grind the dry, uniform powder and pass it through a 170-mesh sieve. Then, put the powder into a graphite mold and place the graphite mold into a spark plasma sintering equipment. Under a sintering pressure of 80 MPa, raise the temperature to 1850°C at a heating / cooling rate of 90°C / min, hold for 25 minutes, and then cool to room temperature to obtain rare earth element stabilized HfC-ZrC-SiCw ultra-high temperature ceramic.
[0050] Example 5: A method for preparing an ultra-high temperature ceramic that combines resistance to long-term ablation and toughness, comprising the following steps:
[0051] Step 1: Weigh 70 parts hafnium carbide powder and 80 parts zirconium carbide powder according to volume fractions, and mix them with silicon hexaboride powder (8% of the total volume of the two powders), yttrium boride (20%) and silicon carbide whiskers (30%) to obtain a mixed powder.
[0052] Step 2: Place the mixed powder into a ball mill jar, add isopropanol to the ball mill jar at a ball:material mass ratio of 4:1, and wet ball mill at a speed of 500 r / min for 15 h to obtain a mixed powder solution.
[0053] Step 3: The mixed powder solution is initially dried by rotary evaporation in a vacuum at a speed of 10 r / min and a temperature of 38°C until the liquid evaporates into block powder. Then, vacuum drying is continued at a temperature of 53°C until a completely dried uniform powder is obtained.
[0054] Step 4: Grind the dry, uniform powder and pass it through a 230-mesh sieve. Then, put the powder into a graphite mold and place the graphite mold into a spark plasma sintering equipment. Under a sintering pressure of 40 MPa, raise the temperature to 1880°C at a heating / cooling rate of 60°C / min, hold for 28 min, and then cool to room temperature to obtain rare earth element stabilized HfC-ZrC-SiCw ultra-high temperature ceramic.
[0055] Example 6: A method for preparing an ultra-high temperature ceramic that combines resistance to long-term ablation and toughness, comprising the following steps:
[0056] Step 1: Weigh out 30 parts hafnium carbide powder and 70 parts zirconium carbide powder according to volume fractions, and mix them with 10% silicon hexaboride powder, 12% lanthanum oxide and lanthanum boride mixed powder, and 20% silicon carbide whiskers, which account for 10% of the total volume of the two powders, to obtain mixed powder.
[0057] Step 2: Place the mixed powder into a ball mill jar, add isopropanol to the ball mill jar at a ball:material mass ratio of 6:1, and wet ball mill at a speed of 450 r / min for 18 h to obtain a mixed powder solution.
[0058] Step 3: The mixed powder solution is initially dried by rotary evaporation in a vacuum at a speed of 12 r / min and a temperature of 45°C until the liquid evaporates into block powder. Then, vacuum drying is continued at a temperature of 55°C until a completely dried uniform powder is obtained.
[0059] Step 4: Grind the dry, uniform powder and pass it through a 250-mesh sieve. Then, put the powder into a graphite mold and place the graphite mold into a spark plasma sintering equipment. Under a sintering pressure of 55 MPa, raise the temperature to 1860°C at a heating / cooling rate of 75°C / min, hold for 30 min, and then cool to room temperature to obtain rare earth element stabilized HfC-ZrC-SiCw ultra-high temperature ceramic.
[0060] Example 7: A method for preparing an ultra-high temperature ceramic that combines resistance to long-term ablation and toughness, comprising the following steps:
[0061] Step 1: Weigh 60 parts hafnium carbide powder and 40 parts zirconium carbide powder according to volume fractions, and mix them with 5% silicon hexaboride powder, 9% yttrium oxide and yttrium boride mixed powder, and 15% silicon carbide whiskers, which account for 5% of the total volume of the two powders, to obtain a mixed powder.
[0062] Step 2: Place the mixed powder into a ball mill jar, add anhydrous ethanol to the ball mill jar at a ball:material mass ratio of 7:1, and wet ball mill at a speed of 350 r / min for 24 h to obtain a mixed powder solution.
[0063] Step 3: The mixed powder solution is initially dried by rotary evaporation in a vacuum at a speed of 20 r / min and a temperature of 50°C until the liquid evaporates into block powder. Then, vacuum drying is continued at a temperature of 60°C until a completely dried uniform powder is obtained.
[0064] Step 4: Grind the dry, uniform powder and pass it through a 150-mesh sieve. Then, put the powder into a graphite mold and place the graphite mold into a spark plasma sintering equipment. Under a sintering pressure of 65 MPa, raise the temperature to 1900℃ at a heating and cooling rate of 100℃ / min, hold for 22 minutes, and then cool to room temperature to obtain rare earth element stabilized HfC-ZrC-SiCw ultra-high temperature ceramic.
[0065] Example 8: A method for preparing an ultra-high temperature ceramic that combines resistance to long-term ablation and toughness, comprising the following steps:
[0066] Step 1: Weigh out 80 parts by volume of hafnium carbide powder and 20 parts by volume of zirconium carbide powder, and mix them with 4% by volume of silicon hexaboride powder, 18% by volume of lanthanum boride, yttrium carbide and yttrium oxide mixed powder and 22% by volume of silicon carbide whiskers to obtain mixed powder.
[0067] Step 2: Place the mixed powder into a ball mill jar, add isopropanol to the ball mill jar at a ball:material mass ratio of 5:1, and wet ball mill at a speed of 480 r / min for 17 h to obtain a mixed powder solution.
[0068] Step 3: The mixed powder solution is initially dried by rotary evaporation in a vacuum at a speed of 16 r / min and a temperature of 38°C until the liquid evaporates into block powder. Then, vacuum drying is continued at a temperature of 52°C until a completely dried uniform powder is obtained.
[0069] Step 4: Grind the dry, uniform powder and pass it through a 210-mesh sieve. Then, put the powder into a graphite mold and place the graphite mold into a spark plasma sintering equipment. Under a sintering pressure of 70 MPa, raise the temperature to 1820°C at a heating and cooling rate of 85°C / min, hold for 26 min, and then cool to room temperature to obtain rare earth element stabilized HfC-ZrC-SiCw ultra-high temperature ceramic.
[0070] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for producing an ultra-high-temperature ceramic having both long-term ablation resistance and toughness, characterized by, Includes the following steps: Step 1: Weigh 20-80 parts of hafnium carbide powder and 20-80 parts of zirconium carbide powder according to volume fractions, and mix them with 3-10% of silicon hexaboride powder, 5-20% of rare earth element compounds and 5-30% of silicon carbide whiskers, which account for 3-10% of the total volume of the two powders, to obtain a mixed powder. The rare earth element compound in step one is one or more of lanthanum oxide, lanthanum boride, yttrium carbide, yttrium oxide, and yttrium boride; Step 2: Place the mixed powder into a ball mill jar and perform wet ball milling at a ball-to-powder mass ratio of 3-8:1 to obtain a mixed powder solution; Step 3: Perform preliminary drying of the mixed powder solution by rotary evaporation under vacuum until the liquid evaporates into block powder, and then continue vacuum drying until a completely dry uniform powder is obtained. Step 4: Grind the dry, uniform powder and sieve it, then put it into a graphite mold. Place the graphite mold into a spark plasma sintering equipment. Under a sintering pressure of 40-80 MPa, raise the temperature to 1750-1900℃ at a heating rate of 50-100℃ / min, hold for 20-30 min, and then cool to room temperature to obtain rare earth element stabilized HfC-ZrC-SiCw ultra-high temperature ceramic. The prepared ultra-high temperature ceramic has uniform microstructure distribution, dense structure and fracture toughness greater than 5MPa.m 1 / 2 The plasma ablation system is resistant to ablation at 2500℃ for more than 600s.
2. The method for preparing ultra-high temperature ceramics with both long-term ablation resistance and toughness as described in claim 1, characterized in that: In step two, wet ball milling is performed using anhydrous ethanol or isopropanol at a speed of 200-500 r / min for 10-24 hours.
3. The method for preparing ultra-high temperature ceramics with both long-term ablation resistance and toughness as described in claim 1, characterized in that: In step three, the rotary evaporation drying speed is 10-20 r / min and the temperature is 35-50℃.
4. The method for preparing ultra-high temperature ceramics with both long-term ablation resistance and toughness as described in claim 1, characterized in that: The vacuum drying temperature in step three is 50-60℃.
5. The method for preparing ultra-high temperature ceramics with both long-term ablation resistance and toughness as described in claim 1, characterized in that: In step four, the sieving process specifically involves passing the material through a 150-250 mesh sieve.