Method for preparing ultra-high temperature ceramic material by low-temperature pressureless rapid prototyping

Abstract

This invention relates to a method for preparing ultra-high temperature ceramic materials using low-temperature, pressureless, and rapid prototyping, belonging to the field of ultra-high temperature ceramic technology. The method involves dispersing polyzirconium dihydrogen phosphate powder in a mixed solvent of ethanol and water, adding an equal mass of F44 phenolic epoxy resin, and concentrating the solution to obtain an adhesive. Subsequently, hafnium carbide powder of different particle sizes is compounded into the adhesive, and boron powder and silicon powder may be selectively added. After uniform mixing, the solvent is removed, the mixture is ground and shaped, and then cured pressureless in air to obtain the ultra-high temperature ceramic material. This invention uses polyzirconium dihydrogen phosphate as a novel curing agent, solving the problems of high porosity and poor heat and ablation resistance in traditional epoxy systems, while retaining its high adhesive strength. The proposed process is low-temperature, pressureless, simple to operate, and rapid in molding, yielding ultra-high temperature ceramic materials with high heat and ablation resistance, suitable for thermal protection in extreme thermal environments such as aerospace.

Description

Technical Field

[0001] This invention relates to a method for preparing ultra-high temperature ceramic materials by low-temperature pressureless rapid prototyping, which belongs to the technical field of ceramic material preparation. Background Technology

[0002] With the development of aerospace technology, the Mach number of spacecraft is constantly increasing, leading to more extreme service environments for high-temperature resistant materials. The nose cone, wing leading edge, rocket engine nozzle, and throat liner of the space shuttle all face severe high-temperature oxidation and ablation environments. Therefore, the development of high-temperature materials that can withstand ablation for extended periods has become an urgent need in this field.

[0003] Among the many high-temperature resistant materials, ultra-high temperature ceramics (UHTCs) have high melting points (most exceeding 2000℃), excellent high-temperature stability and ablation resistance, and have become one of the most promising materials for application in extreme high-temperature ablation environments.

[0004] However, the preparation of ultra-high temperature ceramic materials currently faces a series of challenges, the most significant being the high preparation temperature, long cycle time, difficulty in densification, and demanding equipment requirements, resulting in high manufacturing costs and limiting their widespread application. Currently, the main preparation methods for ultra-high temperature ceramics include high-temperature high-pressure sintering (hot pressing, spark plasma sintering, etc.), polymer precursor conversion, and reactive melting. High-temperature high-pressure sintering typically applies pressure (usually above 30 MPa) during high-temperature sintering (e.g., 1900℃) to promote material densification. This process requires sophisticated equipment and makes the preparation of complex ceramic components difficult. The precursor impregnation and pyrolysis method uses a fiber preform as a framework, filling the preform with a ceramic precursor solution using vacuum or pressure, followed by high-temperature pyrolysis to transform it into inorganic ceramics. Densification is promoted through repeated impregnation-pyrolysis processes. The ultra-high temperature phase formation temperature in this process generally exceeds 1600℃, and multiple cycles are required, making the process extremely cumbersome. Reactive infiltration refers to the process where ultra-high temperature metals or inorganic non-metals (including silicides or alloys) are melted at a certain temperature and infiltrated into a porous ceramic preform under the action of capillary force, where they react chemically with carbon and other materials to prepare ultra-high temperature ceramics. To ensure the formation of the melt and good fluidity, the infiltration temperature is usually higher than 1800 ℃.

[0005] Therefore, developing a low-temperature, pressureless, rapid preparation technology that can be molded according to the traditional resin-based composite material molding method has the advantages of simple process, low equipment requirements, easy large-scale mass production, significant reduction in the production cost of ultra-high temperature ceramics, and easy promotion and application in the future.

[0006] Currently, organic binders are mostly used as low-temperature bonding and shaping materials in the preparation of ultra-high temperature ceramics, and they completely decompose during high-temperature sintering, ultimately producing pure inorganic ultra-high temperature ceramics.

[0007] In recent years, organic / inorganic hybrid materials have been continuously developed and have found certain applications in high-temperature coatings, adhesives, and ablation-resistant materials. The main principle is to mix ceramic powders together using an organic binder that is high-temperature resistant, ablation-resistant, high-strength, highly carbonized, and low-porosity. The organic binder then solidifies and bonds the ceramic powders at a certain temperature, forming an organic / inorganic hybrid material with strength and toughness. During high-temperature use, part of the organic binder decomposes and volatilizes into gas, while the other part carbonizes and bonds with the ceramic powder to become a high-temperature resistant material, achieving the goal of low-temperature molding and high-temperature use.

[0008] However, research on organic / inorganic hybrid materials in the ceramics field is limited. The technical challenge lies in the use of organic binders, which require high bonding strength, high temperature resistance, high degree of ceramization, low porosity, and ablation resistance. Currently, organic / inorganic hybrid materials mostly use organic binders with high carbonization degrees, such as polycarbosilanes and phenolic resins. However, polycarbosilanes have low bonding strength, and phenolic resins have high porosity during the ceramization process, making them unsuitable for preparing hybrid ceramic materials that can withstand long-term temperatures above 2000℃.

[0009] Traditional epoxy resin, as a high-strength organic adhesive, is usually cured and bonded using organic curing agents. It has high bonding strength with ultra-high temperature ceramic powder and excellent overall performance, but its heat resistance and ablation resistance are poor and its porosity is high, making it unsuitable as an adhesive for organic / inorganic hybrid ultra-high temperature ceramics. Summary of the Invention

[0010] To address the problems existing in the prior art, this invention uses polymeric zirconium dihydrogen phosphate as a phenolic resin-type epoxy resin curing agent with good ablation resistance. The reaction between phenolic epoxy resin and hafnium dihydrogen phosphate generates a cured product with both organic and inorganic structures in its chain segment structure, which significantly improves heat resistance. Due to the presence of phenolic structure in the structure, its ablation resistance is superior to that of ordinary epoxy resins and most organic resins. This system overcomes the disadvantages of high porosity and poor heat and ablation resistance of epoxy resin / organic curing agent bonding systems, while maintaining its high bonding strength, and can be used for the preparation of organic / inorganic hybrid ultra-high temperature ceramics.

[0011] The technical solution adopted in this invention is: a method for preparing ultra-high temperature ceramic materials by low-temperature pressureless rapid prototyping, comprising the following steps:

[0012] Step 1: Add the polyzirconium dihydrogen phosphate powder to a mixed solvent of ethanol and water to obtain a mixed solution with a mass percentage of 5%-15%; then add F44 phenolic resin type epoxy resin and concentrate it to obtain a polyzirconium dihydrogen phosphate / F44 phenolic resin type epoxy resin adhesive solution with a mass percentage of 40%-60%; wherein, the mass ratio of polyzirconium dihydrogen phosphate powder to F44 phenolic resin type epoxy resin is 1:1.

[0013] Step 2: 100 parts of a polymeric zirconium dihydrogen phosphate / F44 phenolic resin type epoxy resin adhesive solution are mixed with 50-150 parts of hafnium carbide powder with a particle size of 1 μm, 400-800 parts of hafnium carbide powder with a particle size of 5 μm, 0-30 parts of boron powder with a particle size of 1 μm, and 0-50 parts of silicon powder with a particle size of 1 μm. After mixing evenly, the solvent is removed by heating and then the mixture is ground into powder. The powder is placed in a mold, pressed and formed, and then removed. It is cured in an air environment at 200℃-400℃ under pressureless conditions for 0.3-1 hour to prepare an organic / inorganic hybrid ultra-high temperature ceramic.

[0014] Furthermore, the mixed solvent of ethanol and water is prepared by mixing ethanol and distilled water at a mass ratio of 1:1.

[0015] Furthermore, the mass percentage of the mixed solution is 10%; the mass percentage of the polymeric zirconium dihydrogen phosphate / F44 phenolic resin type epoxy resin adhesive solution is 50%.

[0016] Furthermore, in step 2, 100 parts of 50% by mass of polyzirconium dihydrogen phosphate / F44 epoxy resin adhesive, 50 parts of hafnium carbide powder with a particle size of 1 μm, 400 parts of hafnium carbide with a particle size of 5 μm, 30 parts of boron powder with a particle size of 1 μm, and 25 parts of silicon powder with a particle size of 1 μm are used.

[0017] The specific preparation method is as follows: Ethanol and distilled water are added to the polyzirconium dihydrogen phosphate powder at a mass ratio of 1:1 to prepare a mixed solution with a mass percentage of 10%. Then, an equal mass of F44 phenolic resin-type epoxy resin is added and rotary evaporated to prepare a 50% mass percentage polyzirconium dihydrogen phosphate / F44 phenolic resin-type epoxy resin adhesive. The above binder is 100 parts. Add 50-150 parts of hafnium carbide powder with a particle size of 1μm, 400-800 parts of hafnium carbide powder with a particle size of 5μm, 0-30 parts of boron powder with a particle size of 1μm, and 0-50 parts of silicon powder with a particle size of 1μm. After mixing evenly, heat at 80℃ for 1.5 hours to remove the solvent, grind into powder, place the above mixture in a mold, press at 10MPa to form, take it out, and cure in air at 300℃ under pressureless conditions for 0.5 hours to prepare organic / inorganic hybrid ultra-high temperature ceramic.

[0018] The beneficial effects of this invention are as follows: This invention uses polyzirconium dihydrogen phosphate as a curing agent for phenolic epoxy resin, which overcomes the defects of high porosity and poor heat resistance and ablation resistance of traditional epoxy resin / organic curing agent systems, while retaining its advantage of high bonding strength. Through a low-temperature pressureless rapid prototyping process, this adhesive is compounded with ceramic powders such as hafnium carbide, boron powder, and silicon powder, and organic / inorganic hybrid ultra-high temperature ceramics can be prepared by short-time pressureless curing in an air environment at 300°C. The resulting material has excellent bonding strength, high temperature resistance, and ablation resistance. The process is simple and suitable for the efficient preparation of ultra-high temperature ceramic parts. Attached Figure Description

[0019] Figure 1 This is a photo of the sample before it was ablated.

[0020] Figure 2 This is an SEM image of the sample before ablation.

[0021] Figure 3 This is a photo of the oxyacetylene ablation process.

[0022] Figure 4 This is a SEM image of the oxyacetylene ablation process. Detailed Implementation

[0023] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention, but are not limited thereto, unless otherwise stated.

[0024] The specific embodiments of the present invention are described in detail below with reference to the technical solutions:

[0025] In the following embodiments, hafnium carbide powder with a particle size of 1 μm is abbreviated as 1 μm hafnium carbide, hafnium carbide powder with a particle size of 5 μm is abbreviated as 5 μm hafnium carbide, boron powder with a particle size of 1 μm is abbreviated as 1 μm boron powder, and silicon powder with a particle size of 1 μm is abbreviated as 1 μm silicon powder.

[0026] Example 1

[0027] Preparation method of adhesive solution: Ethanol and distilled water are added to polyzirconium dihydrogen phosphate powder at a mass ratio of 1:1 to prepare a 10% concentration mixed solution. Then, F44 phenolic resin type epoxy resin with an equal mass to polyzirconium dihydrogen phosphate powder is added, and the mixture is rotary evaporated for about one hour to prepare a 50% concentration polyzirconium dihydrogen phosphate / F44 phenolic resin type epoxy resin adhesive solution.

[0028] A phenolic epoxy resin system (e.g., epoxy resin of grade F44) was used to bond silicon carbide specimens. A pressure of 0.005 MPa was applied, and the mixture was cured at 300°C for 0.5 hours. The bond strength was tested according to GB7124: 16 MPa shear strength at room temperature, 8 MPa at 400°C, 5 MPa at 500°C, 3 MPa at 600°C, and 3 MPa at 700°C. This adhesive exhibits high bond strength, excellent heat resistance, and ablation resistance. It can be used as an adhesive for organic / inorganic hybrid ultra-high temperature ceramics.

[0029] A polymeric zirconium dihydrogen phosphate / F44 phenolic resin type epoxy resin adhesive solution was used as the adhesive. 100 parts of the solution were mixed with 50-150 parts of 1μm hafnium carbide ceramic powder, 400-800 parts of 5μm hafnium carbide ceramic powder, 0-30 parts of 1μm boron powder, and 0-50 parts of 1μm silicon powder. After mixing evenly, the mixture was heated at 80℃ for 1.5 hours to remove the solvent, ground into powder, and then placed in a mold. After molding under pressure of 10MPa, the mixture was removed and cured in air at 300℃ under pressureless conditions for 0.5 hours to prepare an organic / inorganic hybrid ultra-high temperature ceramic.

[0030] Table 1 Factor Level Table

[0031]

[0032] Table 2 Orthogonal Experiment Table

[0033]

[0034] Rows I, II, and III represent the sum of the linear ablation rate / mass ablation rate for each factor at different levels, reflecting the overall performance of that factor at different levels. The range R measures the degree of influence of each factor on the results; a larger R value indicates a greater influence of that factor on the experimental results. The optimal formulation ratio was ultimately determined to be 1μm hafnium carbide: 5μm hafnium carbide: 1μm boron powder: 1μm silicon powder at a mass ratio of 50:400:30:25.

[0035] Through orthogonal experiments, the ultra-high temperature ceramic formula of this application was finally determined as follows: 100 parts of 50% polyzirconium dihydrogen phosphate / F44 epoxy resin binder, 50 parts of 1μm hafnium carbide, 400 parts of 5μm hafnium carbide, 30 parts of 1μm boron powder, and 25 parts of 10μm silicon powder. The ceramic powders were mixed together according to the above formula, the solvent was removed, and the powder was ground into a fine powder. The powder was poured into a mold, pressed at 10MPa, and then removed. It was then cured under pressure for 0.5 hours in air at 300℃ for a room temperature compressive strength of 222.8MPa to prepare an organic-inorganic / inorganic hybrid material. During use, it was directly sintered into an ultra-high temperature ceramic. After the oxyacetylene ablation temperature was controlled at 2300℃ for 480s, the compressive strength reached 56.3MPa, the linear ablation rate was 0.182µm / s, and the mass loss on ignition was 2.02mg / s.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing ultra-high temperature ceramic materials by low-temperature pressureless rapid prototyping, characterized in that, Includes the following steps: Step 1: Add the polyzirconium dihydrogen phosphate powder to a mixed solvent of ethanol and water to obtain a mixed solution with a mass percentage of 5%-15%; then add F44 phenolic resin type epoxy resin and concentrate it to obtain a polyzirconium dihydrogen phosphate / F44 phenolic resin type epoxy resin adhesive solution with a mass percentage of 40%-60%; wherein, the mass ratio of polyzirconium dihydrogen phosphate powder to F44 phenolic resin type epoxy resin is 1:

1. Step 2: 100 parts of a polymeric zirconium dihydrogen phosphate / F44 phenolic resin type epoxy resin adhesive solution are mixed with 50-150 parts of hafnium carbide powder with a particle size of 1 μm, 400-800 parts of hafnium carbide powder with a particle size of 5 μm, 15-30 parts of boron powder with a particle size of 1 μm, and 25-50 parts of silicon powder with a particle size of 1 μm. After mixing evenly, the solvent is removed by heating and then the mixture is ground into powder. The powder is placed in a mold, pressed and shaped, and then removed. It is cured in an air environment at 200℃-400℃ under pressureless conditions for 0.3-1 hour to prepare an organic / inorganic hybrid ultra-high temperature ceramic.

2. The method for preparing ultra-high temperature ceramic materials by low-temperature pressureless rapid prototyping according to claim 1, characterized in that, The mixed solvent of ethanol and water is prepared by mixing ethanol and distilled water at a mass ratio of 1:

1.

3. The method for preparing ultra-high temperature ceramic materials by low-temperature pressureless rapid prototyping according to claim 1, characterized in that, The mass percentage of the mixed solution is 10%; the mass percentage of the polymeric zirconium dihydrogen phosphate / F44 phenolic resin type epoxy resin adhesive solution is 50%.

4. The method for preparing ultra-high temperature ceramic materials by low-temperature pressureless rapid prototyping according to claim 1, characterized in that, In step 2, 100 parts of 50% by mass of polyzirconium dihydrogen phosphate / F44 epoxy resin adhesive, 50 parts of hafnium carbide powder with a particle size of 1 μm, 400 parts of hafnium carbide powder with a particle size of 5 μm, 30 parts of boron powder with a particle size of 1 μm, and 25 parts of silicon powder with a particle size of 1 μm are used.

Images