阅读说明：本技术 一种准各向同性高导热c/c复合材料及其制备方法 (Quasi-isotropic high-thermal-conductivity C/C composite material and preparation method thereof ) 是由 黄东 叶崇 刘金水 伍孝 叶高明 吴晃 余洋 于 2020-06-30 设计创作，主要内容包括：本发明涉及核聚变用壁垒材料技术领域,尤其涉及一种准各向同性高导热C/C复合材料及其制备方法。该方法将沥青纤维成网后依次进行预氧化处理和碳化处理,得到碳纤维无纺布；在碳纤维无纺布上涂覆碳量子点改性溶液,并进行干燥处理,再经叠层针刺后得到改性碳纤维无纺布；对改性碳纤维无纺布顺次进行化学结合、气相渗透、前驱体浸渍热解增密、碳化处理和石墨化处理,即得准各向同性高导热C/C复合材料。该法制备的准各向同性高导热C/C复合材料不仅具有较好的界面结合状态,而且明显改善了复合材料的各向异性特征,具有较好的强度和导热性能。(The invention relates to the technical field of barrier materials for nuclear fusion, in particular to a quasi-isotropic high-thermal-conductivity C/C composite material and a preparation method thereof. The method comprises the steps of forming a web of asphalt fibers, and then sequentially carrying out pre-oxidation treatment and carbonization treatment to obtain carbon fiber non-woven fabrics; coating a carbon quantum dot modified solution on the carbon fiber non-woven fabric, drying, and performing lamination and needling to obtain a modified carbon fiber non-woven fabric; and sequentially carrying out chemical combination, gas-phase permeation, precursor impregnation pyrolysis densification, carbonization treatment and graphitization treatment on the modified carbon fiber non-woven fabric to obtain the quasi-isotropic high-thermal-conductivity C/C composite material. The quasi-isotropic high-thermal-conductivity C/C composite material prepared by the method not only has a good interface bonding state, but also obviously improves the anisotropic characteristic of the composite material, and has good strength and thermal conductivity.)

1. A preparation method of a quasi-isotropic high-thermal-conductivity C/C composite material is characterized by comprising the following steps:

1) performing pre-oxidation treatment and carbonization treatment on the asphalt fibers after the asphalt fibers are formed into a net, so as to obtain carbon fiber non-woven fabric;

2) coating a carbon quantum dot modified solution on the carbon fiber non-woven fabric, drying, and performing lamination and needling to obtain a modified carbon fiber non-woven fabric;

3) and sequentially carrying out chemical combination, gas-phase permeation, precursor impregnation pyrolysis densification, carbonization treatment and graphitization treatment on the modified carbon fiber non-woven fabric to obtain the quasi-isotropic high-thermal-conductivity C/C composite material.

2. The preparation method of the quasi-isotropic high thermal conductivity C/C composite material as claimed in claim 1, wherein the pre-oxidation treatment in step 1) is performed under a temperature rise rate of 0.5-1.5 ℃/min to 260-300 ℃.

3. The preparation method of the quasi-isotropic high thermal conductivity C/C composite material according to claim 1 or 2, wherein the carbonization treatment in the step 1) is performed under a protective gas at a temperature of 600-1000 ℃ for 10-60 min, and the cloth cover density of the carbon fiber non-woven fabric is 10-40 g/m²。

4. The preparation method of the quasi-isotropic high thermal conductivity C/C composite material according to claim 1, wherein the carbon quantum dot modification solution in the step 2) is prepared by performing a hydrothermal reaction on an aqueous glucose solution, the concentration of the aqueous glucose solution is 0.8-1.6 g/L, the temperature of the hydrothermal reaction is 160-200 ℃, and the time is 12-36 hours.

5. The preparation method of the quasi-isotropic high thermal conductivity C/C composite material as claimed in claim 1 or 4, wherein the coating amount of the coating in the step 2) is 0.8-1.2L/m²The drying treatment temperature is 80-100 ℃, and the drying treatment time is 1-5 h.

6. The preparation method of the quasi-isotropic high thermal conductivity C/C composite material according to claim 1, wherein the chemical bonding in the step 3) is performed under a protective gas, the gas pressure is a positive pressure condition, the temperature is 400-500 ℃, and the time is 1-2 h; the gas phase permeation is carried out at the pressure of 1-3 kPa, the temperature of 800-1050 ℃ and the time of 100-500 h.

7. The preparation method of the quasi-isotropic high thermal conductivity C/C composite material according to claim 1 or 6, wherein the impregnation, pyrolysis and densification of the precursor in the step 3) are performed under a protective gas, the pressure is 5-10 MPa, the impregnation temperature is 200-280 ℃, and the time is 0.5-1 h.

8. The preparation method of the quasi-isotropic high thermal conductivity C/C composite material according to claim 1 or 6, wherein the pressure of the carbonization treatment in the step 3) is 40-100 MPa, the temperature is 800-1000 ℃, and the time is 10-60 min.

9. The preparation method of the quasi-isotropic high thermal conductivity C/C composite material according to claim 1 or 6, wherein the graphitization treatment in the step 3) is performed under a protective gas, the pressure is positive pressure, the temperature is 2500-3000 ℃, and the time is 10-60 min.

10. The quasi-isotropic high thermal conductive C/C composite material prepared by the preparation method of the quasi-isotropic high thermal conductive C/C composite material according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of barrier materials for nuclear fusion, in particular to a quasi-isotropic high-thermal-conductivity C/C composite material and a preparation method thereof.

Background

The low-clutter current driving is a main means for realizing the steady-state operation of tokamak internationally at present, and a low-clutter antenna adopts a phased multi-junction waveguide array form. The multi-junction waveguide array antenna is composed of 20 main waveguide units, each main waveguide is divided into 8 active sub-waveguides by a power divider dividing into eight parts, a passive sub-waveguide is inserted between two adjacent main waveguide units, and in order to protect an antenna port from plasma current ignition and high-energy particle bombardment, a protection limiter is arranged at the antenna port. The new generation of limiter barrier material adopts high heat conduction C/C composite material to replace the traditional graphite material, and optimizes the anti-sputtering capability and the heat conduction capability of the barrier material.

The existing high-thermal-conductivity C/C composite material system is generally high in anisotropy, the distribution of fibers and pyrolytic carbon on a welding surface and the direction of thermal conductivity are considered when the high-thermal-conductivity C/C composite material system is welded with copper, and the design and the manufacture of the high-thermal-conductivity C/C composite material system are different from those of a traditional three-dimensional C/C composite material. Meanwhile, the high-thermal-conductivity C/C composite material consists of high-thermal-conductivity mesophase pitch-based carbon fibers and matrix carbon and is a multi-component material system. Because the modulus of the high-thermal-conductivity mesophase pitch-based carbon fiber is far higher than that of PAN-based carbon fiber, the modulus is usually more than 800GPa, the weaving process performance is poor, and the mechanical property and the thermal conductivity of the final composite material are obviously reduced due to the fact that the fiber is easily damaged during the forming of a prefabricated body. Finally, the mesophase pitch-based carbon fiber has large surface inertness, and the interface state with matrixes such as pyrolytic carbon, pitch carbon and the like is different from that of the traditional PAN-based carbon fiber, so that special structure regulation and control are required and the interface structure characteristics in a good combination state are obtained.

Disclosure of Invention

The invention aims to provide a quasi-isotropic high-thermal-conductivity C/C composite material and a preparation method thereof.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of a quasi-isotropic high-thermal-conductivity C/C composite material, which comprises the following steps:

1) performing pre-oxidation treatment and carbonization treatment on the asphalt fibers after the asphalt fibers are formed into a net, so as to obtain carbon fiber non-woven fabric;

2) coating a carbon quantum dot modified solution on the carbon fiber non-woven fabric, drying, and performing lamination and needling to obtain a modified carbon fiber non-woven fabric;

3) and sequentially carrying out chemical combination, gas-phase permeation, precursor impregnation pyrolysis densification, carbonization treatment and graphitization treatment on the modified carbon fiber non-woven fabric to obtain the quasi-isotropic high-thermal-conductivity C/C composite material.

Preferably, the pre-oxidation treatment in the step 1) is carried out under the condition that the temperature is raised to 260-300 ℃ at a temperature raising rate of 0.5-1.5 ℃/min.

Preferably, the carbonization treatment in the step 1) is carried out under protective gas at the temperature of 600-1000 ℃ for 10-60 min, and the density of the carbon fiber non-woven fabric surface is 10-40 g/m²。

Preferably, the carbon quantum dot modified solution in the step 2) is prepared by performing a hydrothermal reaction on an aqueous glucose solution, wherein the concentration of the aqueous glucose solution is 0.8-1.6 g/L, the temperature of the hydrothermal reaction is 160-200 ℃, and the time is 12-36 h.

Preferably, the coating amount of the coating in the step 2) is 0.8-1.2L/m²The drying treatment temperature is 80-100 ℃, and the drying treatment time is 1-5 h.

Preferably, the chemical bonding in the step 3) is carried out under a protective gas, the air pressure is a positive pressure condition, the temperature is 400-500 ℃, and the time is 1-2 h; the gas phase permeation is carried out at the pressure of 1-3 kPa, the temperature of 800-1050 ℃ and the time of 100-500 h.

Preferably, the impregnation, pyrolysis and densification of the precursor in the step 3) are carried out under a protective gas, the pressure is 5-10 MPa, the impregnation temperature is 200-280 ℃, and the time is 0.5-1 h.

Preferably, the pressure of the carbonization treatment in the step 3) is 40-100 MPa, the temperature is 800-1000 ℃, and the time is 10-60 min.

Preferably, the graphitization treatment in the step 3) is performed under a protective gas, the air pressure is a positive pressure condition, the temperature is 2500-3000 ℃, and the time is 10-60 min.

The invention also provides the quasi-isotropic high-thermal-conductivity C/C composite material prepared by the preparation method.

The invention has the beneficial effects that:

1) starting from mesophase pitch melt spinning, constructing a planar isotropic fiber network, carbonizing to endow the strength to a preform, performing needling treatment to form a quasi-isotropic fiber preform, enabling the fiber preform to be in a delayed initiation heat conduction state, performing CVI (chemical vapor infiltration) and PIP (poly-p-phenylene) densification, and then performing heat conduction through heat treatment at 2500-3000 ℃, wherein the conventional high-heat-conduction fiber preform is designed in a directional weaving mode, so that the prepared composite material has high anisotropy; and the distribution state of the fibers is difficult to control by means of continuous fiber chopping, net forming and fixing, the steps are complicated and the fibers cannot be organically fused with the densification of the composite material.

2) Aiming at the characteristic of large surface inertia of the mesophase pitch-based carbon fiber, the carbon quantum dots are introduced on the surface of the fiber by spraying a carbon quantum solution, the carbon quantum dots are solidified on the surface of the carbon fiber by combining heat treatment, and then the combination state between the carbon fiber and pyrolytic carbon is improved during chemical vapor infiltration, so that the defect of an interface structure caused by the mismatch of thermal behaviors of the fiber and a matrix in the multi-round heat treatment process of the composite material is greatly reduced. Compared with the C/C composite material without carbon quantum dot modification, the interlayer strength of the two-dimensional C/C composite material is improved from 6-8 MPa to 12-14 MPa.

Detailed Description

The invention provides a preparation method of a quasi-isotropic high-thermal-conductivity C/C composite material, which comprises the following steps:

1) performing pre-oxidation treatment and carbonization treatment on the asphalt fibers after the asphalt fibers are formed into a net, so as to obtain carbon fiber non-woven fabric;

2) coating a carbon quantum dot modified solution on the carbon fiber non-woven fabric, drying, and performing lamination and needling to obtain a modified carbon fiber non-woven fabric;

3) and sequentially carrying out chemical combination, gas-phase permeation, precursor impregnation pyrolysis densification, carbonization treatment and graphitization treatment on the modified carbon fiber non-woven fabric to obtain the quasi-isotropic high-thermal-conductivity C/C composite material.

In the invention, the web formation is preferably carried out by spraying mesophase pitch, pitch fibers are formed into the web under the condition of reciprocating motion in the direction of the metal mesh belt X, Y, and the reciprocating motion speed of the metal mesh belt is preferably 0.5-5 m/min, and more preferably 1-3 m/min.

In the invention, the coal-based or petroleum-based asphalt is preferably sprayed, the softening point of the asphalt is preferably 240-290 ℃, more preferably 250-280 ℃, the content of the mesophase is preferably 80-100%, more preferably 90-95%, the ash content is preferably less than or equal to 200ppm, more preferably less than or equal to 180ppm, and the QI content is preferably 40-60%, more preferably 50-55%.

In the invention, the pressure of the jet spinning is preferably 0.3-5 MPa, more preferably 1-3 MPa, the spinning temperature is preferably 260-310 ℃, more preferably 280-300 ℃, the air knife speed is preferably 5-20 m/s, more preferably 10-15 m/s, and the diameter of the asphalt fiber is preferably 12-20 μm, more preferably 15-18 μm.

In the invention, the atmosphere of the pre-oxidation treatment in the step 1) is air, the temperature of the pre-oxidation treatment is preferably raised to 260-300 ℃ at a heating rate of 0.5-1.5 ℃/min, more preferably raised to 270-280 ℃ at a heating rate of 0.8-1.2 ℃/min, and the temperature is not required to be kept after the temperature is raised.

In the invention, the carbonization treatment in the step 1) is preferably carried out under protective gas, the temperature is preferably 600-1000 ℃, the further preferred is 700-900 ℃, the time is preferably 10-60 min, the further preferred is 30-50 min, and the preferred density of the carbon fiber non-woven fabric surface is 10-40 g/m²More preferably 20 to 30g/m²。

In the invention, the protective gas for carbonization treatment is preferably nitrogen, the heating rate of heating to the carbonization treatment temperature is preferably 5-15 ℃/min, and more preferably 8-12 ℃/min, and the fibers in the carbon fiber non-woven fabric are randomly arranged in a plane.

In the invention, the carbon quantum dot modified solution in the step 2) is preferably prepared by carrying out hydrothermal reaction on an aqueous glucose solution, after the reaction, the aqueous glucose solution is preferably subjected to filtration and centrifugation to obtain an aqueous solution of the carbon quantum dots, the concentration of the aqueous glucose solution is preferably 0.8-1.6 g/L, more preferably 1.0-1.4 g/L, the temperature of the hydrothermal reaction is preferably 160-200 ℃, more preferably 170-190 ℃, the time is preferably 12-36 h, and more preferably 18-24 h.

In the invention, the coating amount of the coating in the step 2) is preferably 0.8-1.2L/m²More preferably 0.9 to 1.1L/m²The temperature of the drying treatment is preferably 80-100 ℃, further preferably 85-90 ℃, and the time is preferably 1-5 hours, further preferably 2-4 hours.

In the invention, the drying treatment is preferably followed by lamination needling, and the fiber volume density of the mesophase pitch-based carbon fiber integral felt is adjusted to be 0.15-0.3 g/cm³The bulk density of the Z-direction fiber is 0.03-0.06 g/cm³Further preferably, the fiber volume density of the mesophase pitch-based carbon fiber integral felt is adjusted to be 0.2-0.25 g/cm³The bulk density of the Z-direction fiber is 0.04-0.05 g/cm³。

In the invention, the chemical bonding in the step 3) is preferably carried out under a protective gas, the gas pressure is preferably a positive pressure condition, the temperature is preferably 400-500 ℃, the time is preferably 420-460 ℃, and the time is preferably 1-2 hours, and the time is preferably 1.5 hours.

In the present invention, the positive pressure refers to a gas state higher than the gas pressure of the normal pressure (i.e., usually, one atmosphere).

In the invention, the chemically combined protective gas is preferably nitrogen, and the heating rate in the process of heating to 400-500 ℃ is preferably 1-5 ℃/min, and more preferably 2-4 ℃/min.

In the invention, the gas phase permeation pressure is preferably 1 to 3kPa, more preferably 2kPa, the temperature is preferably 800 to 1050 ℃, more preferably 850 to 1000 ℃, more preferably 900 to 950 ℃, and the time is preferably 100 to 500 hours, more preferably 200 to 400 hours.

In the invention, the heating rate of the gas phase permeation heating to 800-1050 ℃ is preferably 3-10 ℃/min, and more preferably 5-8 ℃/min.

In the invention, the impregnation, pyrolysis and densification of the precursor in the step 3) are preferably carried out under a protective gas, the protective gas is preferably nitrogen, the pressure is preferably 5-10 MPa, more preferably 6-9 MPa, even more preferably 7-8 MPa, the impregnation temperature is preferably 200-280 ℃, more preferably 220-260 ℃, and the time is preferably 0.5-1 h, even more preferably 0.75 h.

In the invention, the precursor is impregnated with pyrolysis to increase the density, preferably impregnated pitch is used as the precursor, and the density after the increase is preferably>1.75g/cm³Further, it is preferable>1.9g/cm³。

In the present invention, the dipping asphalt is preferably isotropic petroleum asphalt, the softening point of the asphalt is preferably 90 to 140 ℃, more preferably 100 to 120 ℃, the ash content is preferably 200ppm or less, more preferably 180ppm or less, and the QI content is preferably 1% or less, more preferably 0.9% or less.

In the present invention, the heating rate in the process of heating the dipping temperature to 120 ℃ is preferably 1 to 5 ℃/min, more preferably 2 to 4 ℃/min, and the heating rate in the process of heating to the final temperature (200 to 280 ℃) is preferably 0.5 to 1 ℃/min, more preferably 0.6 to 0.8 ℃/min.

In the invention, the pressure of the carbonization treatment in the step 3) is preferably 40-100 MPa, more preferably 50-90 MPa, even more preferably 60-80 MPa, the temperature is preferably 800-1000 ℃, more preferably 850-900 ℃, the time is preferably 10-60 min, even more preferably 20-40 min, and the carbonization treatment is naturally cooled to room temperature.

In the invention, the heating rate in the process of raising the temperature of carbonization treatment to 260 ℃ is preferably 1-5 ℃/min, more preferably 2-4 ℃/min, the heating rate in the process of raising the temperature to 500 ℃ is preferably 0.1-1 ℃/min, more preferably 0.5-0.8 ℃/min, and the heating rate in the process of raising the temperature to the final temperature (800-1000 ℃) is preferably 3-10 ℃/min, more preferably 5-8 ℃/min.

In the invention, the graphitization treatment in the step 3) is preferably performed under a protective gas, the protective gas is preferably argon, the gas pressure is preferably positive pressure, the temperature is preferably 2500-3000 ℃, more preferably 2600-2800 ℃, the time is preferably 10-60 min, more preferably 20-40 min, and the graphitized product is naturally cooled to room temperature after the graphitization treatment.

In the present invention, the temperature increase rate in the temperature increase to 2000 ℃ in the graphitization treatment is preferably 5 to 10 ℃/min, more preferably 6 to 8 ℃/min, and the temperature increase rate in the temperature increase to the final temperature (2500 to 3000 ℃) is preferably 1 to 3 ℃/min, more preferably 2 ℃/min.

The invention also provides the quasi-isotropic high-thermal-conductivity C/C composite material prepared by the preparation method.

In the invention, the thermal conductivity of the quasi-isotropic high thermal conductivity C/C composite material in the direction of X, Y is 260-320W/m.K.

The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.