CN115286407A

CN115286407A - C f /Ta 4 HfC 5 -SiC superhigh temperature resistant composite material and preparation method thereof

Info

Publication number: CN115286407A
Application number: CN202210963512.2A
Authority: CN
Inventors: 万帆; 刘荣军; 王衍飞; 李端; 李俊生; 刘星煜; 马浩林
Original assignee: National University of Defense Technology
Current assignee: National University of Defense Technology
Priority date: 2022-08-11
Filing date: 2022-08-11
Publication date: 2022-11-04

Abstract

Provides a C _f /Ta ₄ HfC ₅ The preparation method of the-SiC superhigh temperature resistant composite material comprises the following steps: s1, modifying a carbon fiber interface by adopting a chemical vapor deposition process; s2, introduction of Ta ₄ HfC ₅ Base body through Ta ₄ HfC ₅ The liquid precursor is used for dipping, curing and pre-cracking the prefabricated member, and high-temperature heat treatment is carried out after repeated for many times to obtain the prefabricated member;and S3, introducing a SiC matrix, introducing a C matrix into the prefabricated part through a precursor impregnation cracking process or a chemical vapor infiltration process, and then obtaining the SiC based on Si-C reaction through a liquid phase or vapor phase siliconizing process. The invention gives full play to the advantages of the siliconizing process, compared with C _f /Ta ₄ HfC ₅ The existing preparation process of the-SiC ultrahigh-temperature ceramic matrix composite shortens the preparation period, increases the material density, and the prepared composite material has good ablation resistance and can be applied to the field of aviation and aerospace thermal protection materials.

Description

C f /Ta 4 HfC 5 -SiC superhigh temperature resistant composite material and preparation method thereof

Technical Field

The invention generally relates to the technical field of ultrahigh-temperature ceramics, in particular to a high-temperature ceramic material C _f /Ta ₄ HfC ₅ -SiC superhigh temperature resistant composite material and a preparation method thereof.

Background

The high Mach number aircraft can generate high dynamic pressure to cause severe pneumatic heating in the flying and atmospheric crossing processes due to extremely high speed, and the sharp leading edge, the wing leading edge and other parts of the high Mach number aircraft are eroded by heat flow and chemical plasma for a long time, so that the local temperature can reach more than 2000 ℃; the hot end of the engine also needs to bear the erosion of corrosive gas generated when the solid propellant burns, and the temperature can reach more than 2000 ℃. The extremely harsh environments described above all impose the following requirements on the use of aircraft thermal protection materials: high melting point, high thermal conductivity, mechanical stability at high temperature, chemical stability and ablation resistance. Therefore, research on the novel high-temperature-resistant thermal protection material has important theoretical significance and application value for guaranteeing the development of the high-Mach-number aircraft technology.

Of the systems of ultra-high temperature ceramics, taC and HfC have ultra-high melting points and high hardness and modulus, and thus have received extensive attention from researchers. Because the atomic radii of Ta and Hf are close, taC and HfC can be infinitely mutually dissolved theoretically, thereby forming Ta _x Hf _1-x C solid solution. Ta due to solid solution strengthening _x Hf _1-x C solidThe melting point of the solution is better than that of TaC and HfC, wherein, the Ta formed when the molar ratio of TaC to HfC is 4 ₄ HfC ₅ The melting point of solid solutions can be as close to 4000 ℃. Because of having ultrahigh melting point, the material also has excellent thermophysical properties and oxidation and ablation resistance of TaC and HfC, ta ₄ HfC ₅ The solid solution has great application prospect in the field of aerospace heat protection.

For Ta ₄ HfC ₅ The research of ultra-high temperature solid solution ceramics mainly focuses on the direct sintering preparation based on the solid solution strengthening principle at present, and the preparation process comprises pressureless, hot pressing, spark plasma sintering and the like. However, taC and HfC both have extremely strong covalent bonds and low self-diffusion coefficients, and the solid-phase method realizes densification by using a diffusion solid solution between two substances, and has extremely high requirements on process parameters such as environmental temperature, pressure and the like. Therefore, it is desired to use Ta ₄ HfC ₅ The method is applied to thermal protection materials, and two common problems in the application field of ultra-high temperature ceramics need to be solved: how to prepare at a lower temperature and how to solve the problem of poor toughness of the ceramic.

Ta is generated by precursor conversion at a lower temperature by a precursor impregnation pyrolysis method (PIP) ₄ HfC ₅ Ceramic, preparation of continuous carbon fiber toughened Ta ₄ HfC ₅ The base composite material provides an effective idea for solving the problems. Meanwhile, considering that the medium-low temperature section of the ultrahigh temperature ceramic has poor oxidation resistance, a component with good oxidation resistance in the medium-low temperature section, such as SiC, can be introduced into the matrix.

CN202110125659.X invention discloses a C _f /Ta ₄ HfC ₅ the-SiC superhigh temperature ceramic matrix composite material and the preparation method thereof are as follows: firstly, depositing an interface coating on the surface of a carbon fiber preform, and then respectively introducing Ta through a PIP (polysilicon-insulator-polysilicon) process ₄ HfC ₅ A substrate and a SiC substrate. C prepared by the invention _f /Ta ₄ HfC ₅ the-SiC composite material has good mechanical property and ablation resistance, but the precursor of the-SiC composite material is purchased from the chemical institute of Chinese academy of sciences, and the Hf-containing polymer and the Ta-containing polymer are firstly prepared and blended, and the allyl phenolic resin is additionally used as a carbon sourceThe process is complex, and the requirements on the accuracy and controllability of each step are high. In addition, ta in the invention ₄ HfC ₅ The substrate and the SiC substrate are introduced through a PIP process, and the repetition period is more, so that the total preparation time of the composite material is longer.

Disclosure of Invention

The invention aims to provide a compound C _f /Ta ₄ HfC ₅ -SiC superhigh temperature resistant composite material and a preparation method thereof. Self-made Ta ₄ HfC ₅ The precursor is prepared by a modified citric acid complexation method, ethanol is used as a solvent, and TaCl is used as a solvent ₅ Is a tantalum source, hfCl ₄ Is a hafnium source, uses citric acid as a complexing agent and prepares Ta by carrying out ester condensation reaction with glycerol ₄ HfC ₅ A liquid phase precursor.

The precursor related by the invention has the advantages of easily obtained raw materials, simple process and Ta ₄ HfC ₅ The liquid precursor has moderate viscosity and good solution stability, and is very suitable for preparing Ta by PIP process ₄ HfC ₅ A base composite material.

The precursor obtained by the invention can obtain nanometer Ta after high-temperature treatment at 1600 DEG C ₄ HfC ₅ The ceramic particles and residual C generated in the carbothermic reduction reaction of the precursor can also provide a part of C source for the subsequent liquid phase or gas phase siliconizing process. The SiC matrix is introduced by a liquid phase or gas phase siliconizing process, so that the overall preparation period of the composite material is shortened, and the composite material with higher density can be obtained.

The invention adopts the technical scheme that _f /Ta ₄ HfC ₅ the-SiC superhigh temperature resistant composite material and the preparation method thereof comprise the following steps:

step 1), cleaning and drying the carbon fiber prefabricated part after removing the glue, then placing the carbon fiber prefabricated part in a chemical vapor deposition furnace, and carrying out carbon fiber interface modification by adopting a chemical vapor deposition process to prepare an interface coating;

step 2) introduction of Ta ₄ HfC ₅ Base body of Ta prepared by modified citric acid complexation ₄ HfC ₅ The liquid precursor is used for dipping, solidifying and pre-cracking the prefabricated memberRepeating the above steps for multiple times, and performing high-temperature thermal treatment to obtain the product;

and 3) introducing a SiC matrix, introducing a C matrix into the prefabricated part through a precursor impregnation cracking process or a chemical vapor infiltration process, and then performing a liquid phase or vapor phase siliconizing process to obtain the SiC based on Si-C reaction at high temperature.

Further, in the step 1), the volume fraction of the carbon fiber preform is preferably 10 to 50%; the carbon fiber interface coating is one or a composite coating of PyC, siC or BN coating.

Further, in the step 2), ta is prepared by a modified citric acid method ₄ HfC ₅ The preferred process for the precursor includes the following steps and requirements: adding citric acid into ethanol as a solvent at 40-60 ℃, wherein the addition amount of the citric acid is fully dissolved to obtain a citric acid ethanol solution according to the addition amount required when the citric acid is saturated as much as possible; stirring continuously, adding TaCl ₅ With HfCl ₄ Sequentially adding the mixture into the citric acid ethanol solution obtained in the step 1) according to a molar ratio of 4 ₄ Hf-citric acid complex solution; stirring continuously at Ta ₄ Adding glycerol and Ta into the Hf-citric acid compound solution ₄ The volume ratio of the Hf-citric acid complex solution is (0.35-0.45): 1, reacting for 60-120 min to obtain the Ta ₄ HfC ₅ A precursor solution.

Further, in the step 2), the curing temperature of the carbon fiber prefabricated part after the precursor is soaked is 150-220 ℃; the pre-cracking temperature is 600-1000 ℃, and the pre-cracking temperature is vacuum or inert atmosphere.

Further, in the step 2), when the steps of dipping, curing and pre-cracking the carbon fiber preform are repeated until the intermediate body is increased in weight<When the concentration is 3 percent or reaches the set intermediate density range, the final heat treatment temperature is 1600-1800 ℃ and the time is 1-2 hours. Preferred is C _f /Ta ₄ HfC ₅ The density range of the intermediate is 1.1-1.8 g/cm ³ 。

Further, in the step 3), the precursor is subjected to dipping and crackingThe precursor for introducing the C matrix is preferably phenolic resin or furan resin, and the preferred C after introducing the C matrix _f /Ta ₄ HfC ₅ The density range of the-C intermediate is 1.3-2.0 g/cm ³ 。

Further, in the step 3), after the chemical vapor infiltration process is introduced into the C matrix, the preferable C is _f /Ta ₄ HfC ₅ The density range of the-C intermediate is 1.3-2.0 g/cm ³ 。

Further, in the step 3), the liquid phase or gas phase siliconizing process is used for preparing C _f /Ta ₄ HfC ₅ When the SiC composite material is used, the preferable reaction temperature is 1650-1750 ℃, and the reaction is carried out for 1-3 h by vacuumizing.

Compared with the prior art, the invention has the advantages that:

ta in the process of the invention ₄ HfC ₅ The precursor raw material is easy to obtain, the process is simple, and the PIP process has strong applicability. The precursor conversion product contains partial residual C, and can provide a certain C source for the subsequent liquid phase or gas phase siliconizing process; the SiC matrix is introduced by a liquid phase or gas phase siliconizing process, so that the overall preparation period of the composite material is shortened, and the composite material with higher density can be obtained.

Drawings

These and/or other aspects and advantages of the present invention will become more apparent and more readily appreciated from the following detailed description of the embodiments of the invention, taken in conjunction with the accompanying drawings of which:

FIG. 1 shows a graph of C obtained in example 1 of the present invention _f /Ta ₄ HfC ₅ -a cross-sectional SEM topography of the SiC composite;

FIG. 2 shows C obtained in example 1 of the present invention _f /Ta ₄ HfC ₅ -a cross-sectional SEM topography of the SiC composite, wherein (a) is the SEM topography at the location indicated by reference point 1 in fig. 1; (b) is a partial enlargement of the portion of the middle block diagram of (a);

FIG. 3 shows C obtained in example 1 of the present invention _f /Ta ₄ HfC ₅ -EDS energy spectrum of SiC composite; wherein (a) is an EDS energy spectrum of the location indicated by the reference point 1 in fig. 1; (b) The EDS energy spectrum for the location identified as 2 in fig. 2 (b).

Detailed Description

In order that those skilled in the art will better understand the invention, the invention will be described in further detail with reference to the drawings and specific embodiments.

Example 1

C _f /Ta ₄ HfC ₅ the-SiC superhigh temperature resistant composite material and the preparation method thereof comprise the following steps:

step 1) placing a three-dimensional needling integral structure prefabricated part with the fiber volume fraction of 30% in a high-temperature furnace, heating to 1400 ℃, then preserving heat for 1h for removing glue, and then cleaning and drying the carbon fiber prefabricated part;

step 2) placing the carbon fiber prefabricated member in a chemical vapor deposition furnace, taking propylene as a carbon source, and depositing a PyC interface at 960 ℃ and 2000Pa for 15h;

step 3) disposing Ta ₄ HfC ₅ A precursor. Firstly, 107.4g of citric acid is added into 200ml of ethanol, and the citric acid ethanol solution is obtained after full stirring at 60 ℃; 53.4g of TaCl were then taken ₅ And 12g HfCl ₄ Sequentially adding into citric acid ethanol solution, and stirring for 60min to obtain Ta ₄ Hf-complex solution; finally, 100ml of glycerol is added into the complex solution, and the mixture is continuously stirred for 60min to obtain Ta ₄ HfC ₅ A precursor solution;

step 4) placing the carbon fiber prefabricated part into an impregnation tank, and introducing the Ta prepared in the step 3) in a vacuum environment ₄ HfC ₅ Precursor, the dipping time is 8h;

step 5) placing the carbon fiber prefabricated member soaked in the step 4) into a high-temperature furnace, and raising the temperature to 220 ℃ for curing for 1h after 90 min;

step 6) placing the prefabricated part solidified in the step 5) into a cracking furnace, heating to 1000 ℃ after 180min, preserving heat for 1h, and cracking in an argon atmosphere;

step 7) circulating for 10 times steps 4-6), then placing the prefabricated part in a high-temperature furnace, and treating for 1h at 1600 ℃ in a vacuum atmosphere to obtain C/Ta ₄ HfC ₅ Intermediate of density 1.10g/cm ³ ；

Step 8) reacting the C/Ta obtained in step 7) ₄ HfC ₅ Placing the composite material in a vacuum tank, and introducing phenolic resin alcohol solution in a vacuum environment, wherein the soaking time is 8 hours;

step 9), heating the impregnated intermediate in the step 8) to 150 ℃ for 120min, and curing for 1h; then raising the temperature to 1000 ℃ in 300min, and preserving the heat for 1h for cracking;

step 10) repeating the steps 8) -9) 1 time to obtain an intermediate with the density of 1.46g/cm ³ 。

Step 11) placing the intermediate obtained in the step 10) into a siliconizing furnace, carrying out liquid phase siliconizing at 1650 ℃, and reacting for 1h to obtain the final C _f /Ta ₄ HfC ₅ -SiC ultra high temperature resistant composite material.

As can be seen from FIG. 1, in this example, C having a high density was obtained _f /Ta ₄ HfC ₅ -SiC composite materials with a low distribution of pores. The density of the composite material measured by an Archimedes drainage method was 2.61g/cm ³ . From the EDS results of FIG. 3, it is clear that the white highlight phase in FIGS. 1 and 2 is Ta ₄ HfC ₅ The matrix, which is distributed both between the bundles of the preform fibers and within the bundles, appears as a dispersed particulate in the interbonding regions, while the intrabundle regions are distributed primarily over the fiber surface and appear as interface-like "layers". The bending property of the composite material in the embodiment is measured by a three-point bending test method under the following test conditions: sample size length x width x height =60mm x 5mm x 4mm, span 50mm, loading rate 0.5mm/s. The fracture toughness of the composite material is measured by adopting a unilateral notch beam three-point bending method, and the test conditions are as follows: the sample size length x width x height =30mm x 2.5mm x 5mm, span 20mm, notch depth 2.5mm, loading rate 0.5mm/s. The test result shows that the average values of the bending strength, the modulus and the fracture toughness of the composite material are respectively 74.5 +/-13.2 MPa, 11.7 +/-0.7 GPa and 3.4 +/-1.2 MPa.m ^1/2 . The composite material ablation resistance is tested by adopting an oxyacetylene flame assessment method under the following test conditions: the sample size is long x wide x thick =50mm x 30mm x 8mm, the oxygen flow is 1500L/h, the pressure is 0.4MPa, the acetylene flow is 1200L/h, the pressure is 0.095MPa, and the examination time is 60s. Examination result display compositionThe material mass ablation rate and the line ablation rate are respectively 10.84mg/s and 11.30 mu m/s, the ablation resistance is good, and the C prepared by the method is shown _f /Ta ₄ HfC ₅ The application potential of the-SiC superhigh temperature resistant composite material in the field of protective materials.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. C _f /Ta ₄ HfC ₅ -SiC superhigh temperature resistant composite material, characterized in that the composite material takes a carbon fiber prefabricated part as a reinforcement, takes one or a composite coating of PyC, siC or BN coating as an interface phase, and takes Ta ₄ HfC ₅ And SiC is used as a matrix, and the volume percentage of the carbon fiber prefabricated part in the composite material is 10-50%.

2. The C of claim 1 _f /Ta ₄ HfC ₅ The preparation method of the-SiC superhigh temperature resistant composite material is characterized by comprising the following steps:

s1, cleaning and drying the carbon fiber prefabricated part after removing the glue, then placing the carbon fiber prefabricated part in a deposition furnace, and carrying out carbon fiber interface modification by adopting a chemical vapor deposition process to form an interface coating on the surface of the carbon fiber of the prefabricated part;

s2, introduction of Ta ₄ HfC ₅ Matrix: utilizing Ta prepared by modified citric acid complexation ₄ HfC ₅ The liquid precursor is used for dipping, curing and pre-cracking the prefabricated member, and high-temperature heat treatment is carried out after the dipping, curing and pre-cracking are repeated for a plurality of times to obtain C _f /Ta ₄ HfC ₅ An intermediate;

s3, introducing a SiC matrix: firstly, the precursor is processed by a precursor impregnation cracking process or a chemical vapor infiltration process at C _f /Ta ₄ HfC ₅ Introducing a C matrix into the intermediate to obtain C _f /Ta ₄ HfC ₅ a-C intermediate, and then generating a SiC matrix based on Si-C reaction at high temperature through a liquid phase or gas phase siliconizing process; namely to obtain the C _f /Ta ₄ HfC ₅ -SiC ultra high temperature resistant composite;

in the step S2: ta prepared by modified citric acid complexation method ₄ HfC ₅ The method of the liquid precursor comprises the following steps: adding TaCl ₅ With HfCl ₄ Sequentially adding the mixture into citric acid ethanol solution, and then adding glycerol to obtain Ta ₄ HfC ₅ A liquid precursor.

3. The C of claim 2 _f /Ta ₄ HfC ₅ The preparation method of the-SiC superhigh temperature resistant composite material is characterized in that in the step S1:

the volume fraction of carbon fibers in the carbon fiber prefabricated part is 10-50%;

the step of removing the glue is to place the fiber prefabricated member at the temperature of 1400 ℃; the environment heat preservation time is 1h;

the interface coating is one or a composite coating of PyC, siC or BN coating.

4. The C of claim 2 _f /Ta ₄ HfC ₅ The preparation method of the-SiC superhigh temperature resistant composite material is characterized in that in the step S2, ta is prepared by a modified citric acid complexation method ₄ HfC ₅ The liquid precursor comprises the following steps:

step 1), adding citric acid into ethanol as a solvent at 40-60 ℃, and fully dissolving to obtain a citric acid ethanol solution;

step 2), stirring continuously, adding TaCl ₅ And HfCl ₄ Sequentially adding the mixture into the citric acid ethanol solution obtained in the step 1) according to a molar ratio of 4 ₄ Hf-citric acid complex solution;

step 3), continuously stirring, at Ta ₄ Adding Hf-citric acid complex solutionGlycerol, glycerol and Ta ₄ The volume ratio of the Hf-citric acid complex solution is (0.35-0.45): 1, reacting for 60-120 min to obtain the Ta ₄ HfC ₅ A liquid precursor solution.

5. The C of claim 2 _f /Ta ₄ HfC ₅ The preparation method of the-SiC superhigh temperature resistant composite material is characterized in that in the step S2: ta ₄ HfC ₅ The curing temperature of the precursor is 150-220 ℃ and the curing time is 1h; the pre-cracking temperature is 600-1000 ℃, and the time is 1h; the environment for curing and pre-cracking is vacuum or inert atmosphere.

6. The C of claim 2 _f /Ta ₄ HfC ₅ The preparation method of the-SiC superhigh temperature resistant composite material is characterized in that in the step S2, when the steps of dipping, curing and pre-cracking are repeated until the weight of the carbon fiber prefabricated part is increased<3 percent or reach the preset density range, and then carrying out high-temperature heat treatment at 1600-1800 ℃ for 1-2 h; the predetermined density range is 1.1 to 1.8g/cm ³ 。

7. The C of claim 2 _f /Ta ₄ HfC ₅ The preparation method of the-SiC superhigh temperature resistant composite material is characterized in that in the step S3, the step of introducing the C matrix by a precursor impregnation cracking process comprises the following steps: vacuum impregnation C with liquid phenolic resin or furan resin as precursor _f /Ta ₄ HfC ₅ Curing and cracking the intermediate, wherein the curing temperature is 150 ℃, and the heat preservation time is 1h; the cracking temperature is 1000 ℃, and the heat preservation time is 1h; repeating the above impregnation, curing and cracking process until C _f /Ta ₄ HfC ₅ The intermediate reaches 1.3 to 2.0g/cm ³ Density within the range.

8. The C of claim 2 _f /Ta ₄ HfC ₅ The preparation method of the-SiC superhigh temperature resistant composite material is characterized in that in the step S3, a chemical vapor infiltration process is adoptedThe step of introducing the C matrix includes: using propylene as carbon source, reaction temperature is 960 ℃, pressure is 500-2000 Pa, gas flow is 150ml/min till C _f /Ta ₄ HfC ₅ The intermediate reaches 1.3 to 2.0g/cm ³ Density within the range.

9. The C of claim 2 _f /Ta ₄ HfC ₅ The preparation method of the-SiC superhigh temperature resistant composite material is characterized in that in the step S3, the liquid phase or gas phase siliconizing process is to mix C _f /Ta ₄ HfC ₅ And (3) placing the-C intermediate in a high-temperature furnace, taking commercially purchased silicon particles as a silicon source, reacting at 1650-1750 ℃, and vacuumizing for 1-3 h.