A layered ablation-resistant ultrahigh temperature ceramic material and its preparation method

Abstract

The present invention discloses a layered ablation-resistant ultrahigh temperature ceramic material and a preparation method thereof. The layered ablation-resistant ultrahigh temperature ceramic material is divided into a high temperature resistant outer layer, an oxidation-resistant middle layer and a high strength inner layer; the high temperature resistant outer layer comprises 30-80 vol.% HfC+10-60 vol.% ZrC+1-10 vol.% SiC. f The composition of the anti-oxidation middle layer is 10~80vol.% HfB2+10~80vol.% ZrB2+10~30vol.% SiC, and the composition of the high-strength inner layer is 70~90vol.% ZrB2+10~30vol.% SiC f The present invention significantly increases the operating temperature of ultra-high temperature ceramic materials, and can meet the ultra-high temperature requirements of 2500℃ to 3000℃ in atmospheric environment, filling the gap of no materials available at this temperature. In addition, the toughness and ablation resistance of the ceramic materials of the present invention are significantly improved. High temperature resistant outer layer and high strength inner layer double SiC f The combination of stress relaxation of the fiber-reinforced layer and the transition layer inhibits crack propagation, making the layered ablation-resistant ultra-high temperature ceramic material have high strength and toughness.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-high temperature ceramics, and in particular relates to a layered ablation-resistant ultra-high temperature ceramic material and a preparation method thereof. Background Art

[0002] Ultra-high-temperature ceramics are a class of materials that maintain physical and chemical stability in high temperatures and reactive atmospheres. They can withstand extreme environmental conditions such as long-duration hypersonic flight, atmospheric reentry, transatmospheric flight, and rocket propulsion systems. They can be used in key areas or components such as aircraft nose cones, wing leading edges, and engine hot ends. With the significant increase in hypersonic flight speed and engine efficiency, the service temperature of hot ends such as nose cones can reach 2500-3000°C. Existing ultra-high-temperature ceramics are unable to meet these requirements, making the development of new ultra-high-temperature ceramics that meet these demands crucial.

[0003] The high-temperature ablation resistance of a material is directly related to the oxidation products formed on the ablated surface. Under high atmospheric temperatures, the ablated surface layer forms a loose ZrO2 structure and a SiO2 glass phase filling the intervening structure. This effectively inhibits further ablation below 1800°C. However, above 1800°C, the SiO2 glass phase rapidly volatilizes under the influence of high-temperature, high-velocity airflow, limiting the material's service life at higher temperatures and for longer periods. Suppressing the volatilization of the SiO2 glass phase on the ablated surface is key to improving the ablation resistance of ultra-high-temperature ceramic-based composites. Several composition optimizations have been developed to improve this performance. Patent document CN202110856783.31 describes improving the ablation resistance of ultra-high-temperature ceramic-based composites by adding rare earth oxides, while patent document CN201410116784.4 describes enhancing the stability of the SiO2 glass phase by adding rare earth compounds. However, none of these optimizations enable the use of ultra-high-temperature ceramic materials in oxygen environments between 2500 and 3000°C.

[0004] Generally, the strength of a material decreases with increasing temperature. When the material temperature reaches 2500-3000°C, the strength of existing ultra-high temperature ceramic materials such as HfB2 and ZrB2 decreases significantly. They are easily peeled and ablated under high-velocity atmospheric erosion, and cannot meet the requirements of use. Carbide ultra-high temperature ceramics such as TaC and HfC still have good high-temperature strength in this temperature range, but their oxidation resistance is poor. They are prone to rapid oxidation and form porous and loose structures, which allows oxygen in the atmosphere to quickly enter the interior and cause rapid ablation damage. At the same time, carbide ceramics such as TaC and HfC are difficult to sinter and densify. Some studies have added SiC, HfB2, MoSi2, TaSi2, etc. to TaC and HfC to form composite ceramic materials to achieve sintering densification and improve their high-temperature mechanical properties (such as literature SAGhaffari et al. J. Eur. Ceram. Soc. 33 (2013) 1479-1484 and Int. J. Refract. Met. H. 93 (2020) 105350), but its high-temperature resistance and ablation resistance temperature still cannot reach 2500-3000°C. Summary of the Invention

[0005] The purpose of the present invention is to address the problem that existing ultra-high temperature ceramic materials cannot meet the requirements of use in an oxidizing environment of 2500-3000°C, and to provide a layered ablation-resistant ultra-high temperature ceramic material and a preparation method thereof. The present invention improves the high-temperature strength of the material by combining the material structure, component ratio and process, and self-assembles to form a multi-layer composite structure during the oxidation and ablation process, producing a capillary self-filling effect, inhibiting the oxidation of the material at high temperature, and greatly improving the operating temperature of the ultra-high temperature ceramic material.

[0006] In order to achieve the above object, the present invention provides the following technical solution: a layered ablation-resistant ultrahigh temperature ceramic material, the layered ablation-resistant ultrahigh temperature ceramic material is divided into a high temperature resistant outer layer, an oxidation-resistant middle layer and a high strength inner layer; the high temperature resistant outer layer is composed of 30-80 vol.% HfC + 10-60 vol.% ZrC + 1-10 vol.% SiC f The composition of the anti-oxidation middle layer is 10-80 vol.% HfB2+10-80 vol.% ZrB2+10-30 vol.% SiC, and the composition of the high-strength inner layer is 70-90 vol.% ZrB2+10-30 vol.% SiC f .

[0007] Furthermore, a transition layer is provided between the high temperature resistant outer layer and the anti-oxidation middle layer, and between the anti-oxidation middle layer and the high strength inner layer; the composition of the transition layer is 70-90 vol.% ZrB2 + 10-30 vol.% SiC f .

[0008] Furthermore, the thickness of the transition layer is 0.5 to 5 mm.

[0009] Furthermore, the thickness of the high-temperature resistant outer layer is 1 to 10 mm, the thickness of the anti-oxidation middle layer is 1 to 30 mm, the thickness of the high-strength inner layer is 5 to 30 mm, and the thickness ratio of the anti-oxidation middle layer to the high-temperature resistant outer layer is 1:1 to 5:1.

[0010] The specific thicknesses of the above-mentioned high-temperature resistant outer layer, anti-oxidation middle layer, high-strength inner layer and transition layer are determined according to the ablation time during actual service. The longer the ablation time, the greater the corresponding thickness.

[0011] The present invention also provides a method for preparing a layered ablation-resistant ultrahigh temperature ceramic material. The layered ablation-resistant ultrahigh temperature ceramic material is divided into a high temperature resistant outer layer, an oxidation-resistant middle layer, and a high strength inner layer. The preparation method comprises:

[0012] S1: High temperature resistant outer layer: 30~80vol.%HfC+10~60vol.%ZrC+1~10vol.%SiC f , Anti-oxidation middle layer: 20~80vol.%HfB2+10~80vol.%ZrB2+10~30vol.%SiC and high strength inner layer: 70~90vol.%ZrB2+10~30vol.%SiC f The raw materials are respectively prepared and mixed in a certain proportion to obtain an outer layer raw material powder, a middle layer raw material powder and an inner layer raw material powder, and the three types of raw material powders are dry-milled and mixed under a nitrogen or inert gas protective atmosphere, and the ball milling medium is any one or more of HfC ceramic balls, ZrC ceramic balls, ZrB2 ceramic balls, HfB2 ceramic balls, ZrO2 ceramic balls, HfO2 ceramic balls and SiC ceramic balls, and the ball milling time is 1 to 50 hours;

[0013] S2: After ball milling, the three types of raw material powders are cold-pressed into blocks to obtain outer layer raw material blocks, middle layer raw material blocks, and inner layer raw material blocks;

[0014] S3: stacking the inner layer raw material block, the middle layer raw material block and the outer layer raw material block in sequence, adding transition layer powder between the three types of raw material blocks, and performing secondary cold pressing after stacking; the transition layer powder is 70-90 vol.% ZrB2 + 10-30 vol.% SiC f ;

[0015] S4: Sintering the stacked blocks formed by secondary cold pressing in a vacuum or inert atmosphere to obtain a layered ablation-resistant ultrahigh temperature ceramic material; wherein the sintering temperature is 1850-2250° C. and the sintering pressure is 50-250 MPa.

[0016] Furthermore, the thickness of the high-temperature resistant outer layer is 1 to 10 mm, the thickness of the anti-oxidation middle layer is 1 to 30 mm, the thickness of the high-strength inner layer is 5 to 30 mm, and the thickness ratio of the anti-oxidation middle layer to the high-temperature resistant outer layer is 1:1 to 5:1; the thickness of the transition layer is 0.5 to 5 mm.

[0017] Furthermore, in step S1, the raw material powder after ball milling needs to be screened to select raw material powder with a particle size of 250 to 350 meshes.

[0018] Furthermore, the cold pressing in step S2 and step S3 includes molding and cold isostatic pressing;

[0019] The sintering method in step S4 includes hot pressing, spark plasma sintering or hot isostatic pressing.

[0020] Furthermore, the inert gas includes argon, helium, neon, krypton and xenon.

[0021] Furthermore, the step S3 further includes: adding 0.1 to 3 wt.% of a binder to the transition layer powder, performing a vacuum heat treatment at 400 to 500° C. after stacking to decompose and remove the binder, and then performing secondary cold pressing.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The layered ablation-resistant ultra-high temperature ceramic material and its preparation method provided by the present invention improve the high-temperature strength of the material through the design of material structure, component ratio and process. It self-assembles to form a multilayer composite structure during the oxidation and ablation process, produces a capillary self-filling effect, inhibits the oxidation and ablation of the material at high temperature, and greatly increases the operating temperature of the ultra-high temperature ceramic material. It can meet the ultra-high temperature use requirements of 2500℃ to 3000℃ in atmospheric environment, filling the gap of no material available at this temperature.

[0024] 2. Compared with traditional ultra-high temperature ceramic materials (such as ZrB2+SiC), the layered ablation-resistant ultra-high temperature ceramic material prepared by the method of the present invention has significantly improved toughness and ablation resistance. f The combination of stress relaxation of the fiber-reinforced layer and the transition layer inhibits crack propagation, making the layered ablation-resistant ultra-high temperature ceramic material have high strength and toughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 This is a schematic diagram of the anti-oxidation and ablation mechanism of the layered ablation-resistant ultrahigh temperature ceramic material of the present invention;

[0027] Figure 2 A schematic cross-sectional view of a layered ablation-resistant ultrahigh temperature ceramic material provided by an embodiment of the present invention;

[0028] Figure 3 A schematic flow chart of a method for preparing a layered ablation-resistant ultrahigh temperature ceramic material provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be described in detail below with reference to the accompanying drawings. Unless there is any conflict, the features of the following embodiments and implementations may be combined with each other.

[0030] The present invention provides a method for preparing a layered ablation-resistant ultrahigh temperature ceramic material, such as Figure 3 As shown, including:

[0031] (1) High temperature resistant outer layer: 30-80 vol.% HfC + 10-60 vol.% ZrC + 1-10 vol.% SiC f , Anti-oxidation middle layer: 10~80vol.%HfB2+10~80vol.%ZrB2+10~30vol.%SiC and high strength inner layer: 70~90vol.%ZrB2+10~30vol.%SiC f The raw materials are respectively prepared and mixed in a certain proportion to obtain an outer layer raw material powder, a middle layer raw material powder and an inner layer raw material powder, and the three types of raw material powders are dry-milled and mixed under a nitrogen or inert gas protective atmosphere, and the ball milling medium is any one or more of HfC ceramic balls, ZrC ceramic balls, ZrB2 ceramic balls, HfB2 ceramic balls, ZrO2 ceramic balls, HfO2 ceramic balls and SiC ceramic balls, and the ball milling time is 1 to 50 hours;

[0032] Specifically, firstly, ceramic balls such as ZrO2 (zirconium dioxide), HfO2 (hafnium dioxide), and SiC with a diameter of 5mm to 20mm are weighed and placed in a ball mill of the same material. Then, according to the three component systems of high-temperature resistant outer layer, anti-oxidation middle layer and high-strength inner layer, high-purity HfC (hafnium carbide), ZrC (zirconium carbide), ZrB2 (zirconium diboride), HfB2 (hafnium diboride), SiC (silicon carbide), SiC f (Silicon carbide ceramic fiber) and other ultra-high temperature ceramic raw material powders are weighed according to the above proportions and placed in a ball mill jar with ceramic balls placed in it. The ball mill jar filled with powders is vacuumed and the vacuum degree in the jar reaches 10 -2Pa below, then pass high-purity argon or nitrogen for cleaning, cycle vacuuming and inert atmosphere cleaning, repeat for more than 3 times, and then dry ball milling under high-purity argon or nitrogen protective atmosphere. The ball milling time is 1 to 50 hours. The specific ball milling time is determined by the diameter of the raw material powder. The coarser the raw material powder, the longer the ball milling time. After ball milling, the ball milled powder with a particle size of 250 to 350 mesh is screened for use.

[0033] The steps of vacuuming the ball mill and cleaning with inert gas can also be replaced by other methods: the ball mill is placed in a glove box with an oxygen content of less than 1 ppm for operation.

[0034] (2) The three types of raw material powders after ball milling are cold pressed into blocks respectively to obtain outer layer raw material blocks, middle layer raw material blocks and inner layer raw material blocks; at this time, the relative density of the blocks is 55-65%.

[0035] Among them, when the final shape of the ultra-high temperature ceramic material is a plate, compression molding should be used for cold pressing of the three types of raw material powders; when the final shape of the ultra-high temperature ceramic material is a cone or curved surface, cold isostatic pressing should be used for cold pressing of the three types of raw material powders.

[0036] (3) The inner layer raw material block, the middle layer raw material block and the outer layer raw material block are stacked in sequence, and transition layer powder is added between the three types of raw material blocks, and then secondary cold pressing is performed after stacking; the transition layer powder is 70-90 vol.% ZrB2 + 10-30 vol.% SiC f ;

[0037] Specifically: When the final ultra-high temperature ceramic material is in the shape of a plate, the three types of raw materials are cold-pressed into a plate shape. First, the high-strength inner layer plate is placed flat, and the transition layer powder is spread on top of it. Then, the antioxidant middle layer plate is placed and the transition layer powder is spread on top of it. Finally, the high-temperature resistant outer layer plate is placed and compacted for the second time through cold isostatic pressing.

[0038] When the final ultra-high-temperature ceramic material is conical or curved, the stacking order remains unchanged. To ensure uniform thickness during transition powder placement, 0.1-3 wt.% of a binder is added to the transition layer powder to impart a certain viscosity that allows adhesion to the surface of the cold-pressed blocks formed from the three types of raw materials. After stacking, the blocks are heat-treated at 400-500°C in a vacuum for one hour to decompose and remove the binder. A secondary compaction step is then performed via cold isostatic pressing. The binder is PVA (polyvinyl alcohol), and PVB is also an alternative binder.

[0039] (4) Sintering the stacked blocks formed by secondary cold pressing in a vacuum or inert atmosphere to obtain a layered ablation-resistant ultra-high temperature ceramic material, the density of which will reach more than 95%; wherein, the sintering temperature is 1850-2250°C, and the sintering pressure is 50-250MPa.

[0040] Specifically, the stacked blocks formed by secondary cold pressing are placed in a mold of a sintering device such as a vacuum furnace, SPS (Spark Plasma Sintering, spark plasma sintering), a hot pressing furnace or hot isostatic pressing, and sintered into multi-layer ultra-high temperature ceramic materials by hot pressing, spark plasma sintering or hot isostatic pressing in a vacuum or inert atmosphere protection environment. The sintering temperature is 1850-2250°C, and the sintering pressure is 50-250MPa. The specific sintering conditions vary according to different component ratios: the higher the HfC content in the high-temperature resistant outer layer, the higher the corresponding sintering temperature; the thicker the final molded block, the greater the corresponding sintering pressure required; for a specific component ratio and block thickness, the sintering temperature can be appropriately reduced when the sintering pressure is increased.

[0041] Example 1:

[0042] The layered ablation-resistant ultrahigh temperature ceramic material provided in an embodiment of the present invention has the following components:

[0043] The composition of the high temperature resistant outer layer is 70vol.%HfC+20vol.%ZrC+10vol.%SiC f The composition of the anti-oxidation middle layer is 60vol.% HfB2+20vol.% ZrB2+20vol.% SiC, and the composition of the high-strength inner layer is 70vol.% ZrB2+30vol.% SiC f .

[0044] The thickness of the high temperature resistant outer layer is 5mm, the thickness of the anti-oxidation middle layer is 10mm, the thickness of the high strength inner layer is 10mm, and the thickness of the transition layer is 0.5mm. Figure 2 FIG. 1 is a schematic cross-sectional view of a layered ablation-resistant ultrahigh temperature ceramic material according to the present invention.

[0045] The method for preparing the layered ablation-resistant ultrahigh temperature ceramic material provided in this embodiment includes the following steps:

[0046] S1: Mix and prepare the ingredients to obtain three types of raw material powder:

[0047] The high-temperature resistant outer layer, the antioxidant middle layer, and the high-strength inner layer are prepared and mixed according to the composition ratio to obtain three types of raw material powders. These three types of raw material powders are placed in the ball milling tank of a high-energy ball mill and dry-milled under a protective atmosphere of high-purity argon, helium, neon, krypton, xenon, or nitrogen. The ball milling medium is SiC balls, and the ball milling time is 25 hours.

[0048] S2: Three types of raw material powders are cold pressed into shape separately:

[0049] The three types of raw material powders of the high-temperature resistant outer layer, the anti-oxidation middle layer and the high-strength inner layer mixed by ball milling are placed in a cold isostatic press respectively, and cold pressed into blocks with a relative density of 60%.

[0050] S3: Stacking of cold-pressed blocks made from three types of raw materials:

[0051] The high-strength inner layer, the anti-oxidation middle layer and the high-temperature resistant outer layer are stacked in order from bottom to top, and 80vol.% ZrB2+20vol.% SiC is added between the three types of raw material blocks. f The transition layer powder has a thickness of 0.5 mm and is stacked and then subjected to secondary cold isostatic pressing.

[0052] S4: Powder sintering

[0053] The stacked blocks, after secondary compaction, were placed in a hot isostatic pressing furnace and sintered to form a multi-layer ultra-high temperature ceramic material at a sintering temperature of 2150°C and a sintering pressure of 150 MPa. The relative density after sintering was 98.3%.

[0054] The layered ablation-resistant ultra-high temperature ceramic material prepared by the above composition and process steps is characterized by HfC and SiC in the high temperature resistant outer layer. f The high SiC content produces more micro-nanoscale micropores and HfO2 during the oxidation ablation process. At the same time, the high SiC content in the anti-oxidation middle layer can produce more SiO2 glass phase, thereby achieving a more significant capillary self-filling effect and volatile cooling effect. The high temperature gradient of the high-temperature resistant outer layer is large, making it suitable for short-term service at extremely high temperatures (3000°C). The layered ablation-resistant ultra-high temperature ceramic material prepared by this composition and process steps has a room temperature flexural strength of 678MPa and a room temperature fracture toughness of 6.5MPa·m 1 / 2 When ablated with an oxyacetylene flame at 2500°C for 5 minutes, the thickness of the ablated layer was only 578μm, meeting the requirements for use at this temperature. When ablated with an oxyacetylene flame at 3000°C for 5 minutes, the thickness of the ablated layer was 2383μm, with no material falling off or obvious cracks. The interlayer structure between the anti-oxidation middle layer and the high-temperature resistant outer layer was intact, meeting the requirements for use at this temperature.

[0055] Example 2:

[0056] The layered ablation-resistant ultrahigh temperature ceramic material provided in an embodiment of the present invention has the following components:

[0057] The composition of the high temperature resistant outer layer is 50vol.% HfC+45vol.% ZrC+5vol.% SiC f The composition of the anti-oxidation middle layer is 30vol.% HfB2+60vol.% ZrB2+10vol.% SiC, and the composition of the high-strength inner layer is 70vol.% ZrB2+30vol.% SiC f .

[0058] The thickness of the high-temperature resistant outer layer is 3mm, the thickness of the anti-oxidation middle layer is 10mm, the thickness of the high-strength inner layer is 10mm, and the thickness of the transition layer is 0.5mm.

[0059] The method for preparing the layered ablation-resistant ultrahigh temperature ceramic material provided in this embodiment includes the following steps:

[0060] S1: Mix and prepare the ingredients to obtain three types of raw material powder:

[0061] According to the composition ratio of the high temperature resistant outer layer, the anti-oxidation middle layer and the high strength inner layer, the ingredients are respectively prepared and mixed to obtain three types of raw material powders: HfC, ZrC, ZrB2, HfB2, SiC, SiC f The three types of raw material powders were weighed and mixed according to a specific ratio. They were placed in the ball milling jar of a high-energy ball mill and dry-milled under a high-purity argon or nitrogen protective atmosphere. The ball milling medium was SiC balls and the ball milling time was 25 hours.

[0062] S2: Three types of raw material powders are cold pressed into shape separately:

[0063] The three types of raw material powders of the high-temperature resistant outer layer, the anti-oxidation middle layer and the high-strength inner layer mixed by ball milling are placed in a cold isostatic press respectively, and cold pressed into blocks with a relative density of 60%.

[0064] S3: Stacking of cold-pressed blocks made from three types of raw materials:

[0065] The high-strength inner layer, the anti-oxidation middle layer and the high-temperature resistant outer layer are stacked in order from bottom to top, and 90vol.% ZrB2+10vol.% SiC is added between the three types of raw material blocks. f The transition layer powder has a thickness of 0.5 mm and is stacked and then subjected to secondary cold isostatic pressing.

[0066] S4: Powder sintering

[0067] The stacked blocks after secondary compaction are placed in a hot isostatic pressing furnace and sintered into a multi-layer ultra-high temperature ceramic material at a sintering temperature of 1950°C and a sintering pressure of 150 MPa, with a relative density of 96.7% after sintering.

[0068] The layered ablation-resistant ultra-high temperature ceramic material prepared by the above composition and process steps is characterized by HfC and SiC in the high temperature resistant outer layer. fThe content is low, resulting in fewer micro-nanoscale micropores during oxidation ablation. At the same time, the SiC content in the anti-oxidation middle layer is low, which can produce less SiO2 glass phase, weaker capillary self-filling effect and volatile cooling effect, and smaller temperature gradient in the high-temperature resistant outer layer, making it suitable for long-term service at lower temperatures (2500°C). At the same time, the layered ablation-resistant ultra-high temperature ceramic material prepared by this composition and process steps has low HfC and HfB2 contents, and the corresponding material density is low, which can effectively reduce the material weight; its room temperature flexural strength is 646MPa, and its room temperature fracture toughness is 5.2MPa·m 1 / 2 When ablated at 2500℃ with an oxyacetylene flame for 30 minutes, the thickness of the ablated layer is 1930μm, with no material falling off or obvious cracks. The interlayer structure between the anti-oxidation middle layer and the high-temperature resistant outer layer is complete, meeting the requirements for use at this temperature.

[0069] Example 3: The difference from Example 1 is that the high temperature resistant outer layer composition is 80vol.%HfC+10vol.%ZrC+10vol.%SiC f The composition of the anti-oxidation middle layer is 80vol.% HfB2+10vol.% ZrB2+10vol.% SiC, and the composition of the high-strength inner layer is 90vol.% ZrB2+10vol.% SiC f ; The preparation method and steps are the same as above and will not be repeated here.

[0070] Example 4: Different from Example 1, the high temperature resistant outer layer composition is 30vol.% HfC+60vol.% ZrC+10vol.% SiC f The composition of the anti-oxidation middle layer is 10vol.% HfB2+80vol.% ZrB2+10vol.% SiC, and the composition of the high-strength inner layer is 70vol.% ZrB2+30vol.% SiC f ; The preparation method and steps are the same as above and will not be repeated here.

[0071] Example 5: Different from Example 1, the composition of the high temperature resistant outer layer is 69vol.%HfC+30vol.%ZrC+1vol.%SiC f The composition of the anti-oxidation middle layer is 40vol.% HfB2+30vol.% ZrB2+30vol.% SiC, and the composition of the high-strength inner layer is 80vol.% ZrB2+20vol.% SiC f ; The preparation method and steps are the same as above and will not be repeated here.

[0072] It should be noted that in other embodiments of the present invention, within the scope of the steps, components, ratios, and process parameters recorded in the present invention, other different schemes obtained by making specific selections can all achieve the technical effects recorded in the present invention, so the present invention will no longer list them one by one.

[0073] The mechanism of the present invention is as follows: the layered ablation-resistant ultra-high temperature ceramic material is designed with a unique interlayer component system combination according to the temperature gradient characteristics of the material during high temperature ablation and the chemical and physical reactions during the ablation process. f Oxidation and volatilization occur and a large number of micro-nanoscale micropores are generated, which guide the oxygen in the atmosphere to quickly enter the upper surface of the anti-oxidation middle layer, causing the SiC in the anti-oxidation middle layer to oxidize and produce a SiO2 glass phase. The SiO2 glass phase continues to enter the high-temperature resistant outer layer through the capillary self-filling effect, inhibiting oxygen from further entering the interior of the material. At the same time, the SiO2 glass phase flows from the inside of the material to the outside through the capillary self-filling effect and volatilizes on the surface of the material, cooling the high-temperature resistant outer layer in the form of liquid phase flow, causing the temperature in the high-temperature resistant outer layer to drop rapidly along the surface inward, while the HfC and ZrC in the high-temperature resistant outer layer oxidize to form HfO2 and ZrO2, acting as a heat insulation layer, keeping the temperature of the anti-oxidation middle layer below 2000℃, and generating a SiO2 glass state between the high-temperature resistant outer layer and the anti-oxidation middle layer, providing a glass phase for the capillary self-filling effect and inhibiting oxygen from entering the anti-oxidation middle layer, ensuring sufficient anti-ablation performance. At the same time, the high-strength inner layer is SiC f Fiber-reinforced ZrB2 ensures that the layered ablation-resistant ultra-high temperature ceramic material has sufficiently high strength. Figure 1 .

[0074] The above embodiments are intended only to illustrate the design concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The scope of protection of the present invention is not limited to the above embodiments. Therefore, any equivalent changes or modifications made based on the principles and design concepts disclosed in the present invention are within the scope of protection of the present invention.

Claims

1. A layered ablation-resistant ultrahigh temperature ceramic material, characterized in that: The layered ablation-resistant ultra-high temperature ceramic material is divided into a high-temperature resistant outer layer, an oxidation-resistant middle layer and a high-strength inner layer; the composition of the high-temperature resistant outer layer is 30~80vol.%HfC + 10~60vol.%ZrC + 1~10vol.%SiC f The composition of the anti-oxidation middle layer is 10~80 vol.%HfB2 + 10~80 vol.%ZrB2 + 10~30 vol.%SiC, and the composition of the high-strength inner layer is 70~90 vol.%ZrB2 + 10~30 vol.%SiC f ; A transition layer is provided between the high temperature resistant outer layer and the anti-oxidation middle layer, and between the anti-oxidation middle layer and the high strength inner layer; the composition of the transition layer is 70-90 vol.% ZrB2 + 10-30 vol.% SiC f .

2. The layered ablation-resistant ultrahigh temperature ceramic material according to claim 1, characterized in that: The thickness of the transition layer is 0.5-5 mm.

3. The layered ablation-resistant ultrahigh temperature ceramic material according to claim 1, characterized in that: The thickness of the high-temperature resistant outer layer is 1-10 mm, the thickness of the anti-oxidation middle layer is 1-30 mm, the thickness of the high-strength inner layer is 5-30 mm, and the thickness ratio of the anti-oxidation middle layer to the high-temperature resistant outer layer is 1:1-5:

1.

4. A method for preparing a layered ablation-resistant ultrahigh temperature ceramic material, characterized in that: The layered ablation-resistant ultrahigh temperature ceramic material comprises a high temperature resistant outer layer, an oxidation-resistant middle layer, and a high strength inner layer; and the preparation method thereof comprises: S1: High temperature resistant outer layer: 30~80vol.%HfC + 10~60vol.%ZrC + 1~10vol.%SiC f , Anti-oxidation middle layer: 10~80 vol.%HfB2 + 10~80 vol.%ZrB2 + 10~30vol.%SiC and high strength inner layer: 70~90 vol.%ZrB2+ 10~30 vol.%SiC f The raw materials are respectively prepared and mixed in a certain proportion to obtain an outer layer raw material powder, a middle layer raw material powder and an inner layer raw material powder, and the three types of raw material powders are dry-milled and mixed under a nitrogen or inert gas protective atmosphere, and the ball milling medium is any one or more of HfC ceramic balls, ZrC ceramic balls, ZrB2 ceramic balls, HfB2 ceramic balls, ZrO2 ceramic balls, HfO2 ceramic balls and SiC ceramic balls, and the ball milling time is 1 to 50 hours; S2: After ball milling, the three types of raw material powders are cold-pressed into blocks to obtain outer layer raw material blocks, middle layer raw material blocks, and inner layer raw material blocks; S3: stack the inner layer raw material block, the middle layer raw material block and the outer layer raw material block in sequence, and add transition layer powder between the three types of raw material blocks, and then perform secondary cold pressing after stacking; the transition layer powder is 70~90 vol.% ZrB2 + 10~30 vol.% SiC f ; S4: Sintering the stacked blocks formed by secondary cold pressing in a vacuum or inert atmosphere to obtain a layered ablation-resistant ultrahigh temperature ceramic material; wherein the sintering temperature is 1850~2250℃ and the sintering pressure is 50~250MPa.

5. The method for preparing a layered ablation-resistant ultrahigh temperature ceramic material according to claim 4, characterized in that: The thickness of the high-temperature resistant outer layer is 1~10mm, the thickness of the anti-oxidation middle layer is 1~30mm, the thickness of the high-strength inner layer is 5~30mm, and the thickness ratio of the anti-oxidation middle layer to the high-temperature resistant outer layer is 1:1~5:1; the thickness of the transition layer is 0.5~5mm.

6. The method for preparing a layered ablation-resistant ultrahigh temperature ceramic material according to claim 4, characterized in that: In the step S1, the raw material powder after ball milling needs to be screened to select raw material powder with a particle size of 250 to 350 meshes.

7. The method for preparing a layered ablation-resistant ultrahigh temperature ceramic material according to claim 4, characterized in that: The cold pressing in step S2 and step S3 includes molding and cold isostatic pressing; The sintering method in step S4 includes hot pressing, spark plasma sintering or hot isostatic pressing.

8. The method for preparing a layered ablation-resistant ultrahigh temperature ceramic material according to claim 4, characterized in that: The inert gas includes argon, helium, neon, krypton and xenon.

9. The method for preparing a layered ablation-resistant ultrahigh temperature ceramic material according to claim 4, characterized in that: The step S3 further includes: adding 0.1-3 wt.% of a binder to the transition layer powder, performing a vacuum heat treatment at 400-500° C. after stacking to decompose and remove the binder, and then performing secondary cold pressing.

Images