阅读说明：本技术 一种均质高碳化硼含量的碳化硼/铝复合材料及制备方法 (Homogeneous boron carbide/aluminum composite material with high boron carbide content and preparation method thereof ) 是由 程亮 庞晓轩 罗昊 鲜亚疆 刘向东 吴早明 张鹏程 李强 刘炳刚 晏朝晖 龙亮 于 2021-05-20 设计创作，主要内容包括：本发明公开了一种均质高B-4C含量的B-4C/Al复合材料及制备方法,属于粉末冶金和材料技术领域,解决现有技术中高B-4C含量的B-4C/Al复合材料难以烧结致密化的问题。本发明的制备方法包括按设计要求体积比将粉末态的B-4C原材料和铸锭态的Al原材料依次装入包套中进行除气-封装处理后,在外加力场辅助作用下进行两步法烧结,其中第一步烧结温度T-I低于Al原材料的熔点；第二步烧结温度T-(II)高于Al原材料的熔点；第一步烧结时施加的力场F-I大于第二步烧结施加的力场F-(II)。本发明的方法一次致密化即可实现快速制备高B-4C含量的B-4C/Al三维网状结构复合材料；无需混料工序,无需压制成型工序,过程可控。(The invention discloses a homogeneous high B 4 B of C content 4 A C/Al composite material and a preparation method thereof, belongs to the technical field of powder metallurgy and materials, and solves the problem of high B in the prior art 4 B of C content 4 The C/Al composite material is difficult to sinter and densify. The preparation method comprises the step of mixing the powder B according to the volume ratio required by design 4 Sequentially filling the C raw material and the cast ingot Al raw material into a sheath for degassing-packaging treatmentSintering in two steps under the assistance of an external force field, wherein the sintering temperature T in the first step I Lower than the melting point of the Al raw material; second step sintering temperature T II Higher than the melting point of the Al raw material; force field F applied during the first sintering step I Larger than the force field F applied in the second sintering step II . The method can realize the rapid preparation of the high B through one-time densification 4 B of C content 4 C/Al three-dimensional net structure composite material; the material mixing process and the compression molding process are not needed, and the process is controllable.)

1. Homogeneous high B₄B of C content₄The preparation method of the C/Al composite material is characterized by comprising the following steps: b in powder state is mixed according to the volume ratio required by design₄Sequentially loading the C raw material and the cast ingot Al raw material into a degassing sheath tool for degassing-packaging treatment, and then sintering by a two-step method under the auxiliary action of an external force field, wherein the sintering temperature T in the first step_ILower than the melting point of the Al raw material; second step sintering temperature T_IIHigher than the melting point of the Al raw material; force field F applied during the first sintering step_ILarger than the force field F applied in the second sintering step_II。

2. A homogeneous high B according to claim 1₄B of C content₄The preparation method of the C/Al composite material is characterized in that B₄The particle size range of the raw material C is 0.1-100 mu m; or/and the Al raw material comprises pure aluminum or an aluminum alloy.

3. A homogeneous high B according to claim 1₄B of C content₄The preparation method of the C/Al composite material is characterized in that B₄The volume ratio of the C raw material to the Al raw material is more than or equal to 1;

preferably 1, 1.5 or 1.2.

4. A homogeneous high B according to claim 1₄B of C content₄Preparation method of C/Al composite materialThe device is characterized in that the degassing sheath tool is a double-degassing sheath tool and comprises a metal sheath main body, a top end cover and a bottom end cover, wherein a degassing pipeline I is arranged on the top end cover, and a degassing pipeline II is arranged on the bottom end cover;

after the bottom end cover, the degassing pipeline II and the metal sheath main body are sealed, B is added₄C raw material and Al raw material; sealing the top end cover and the metal sheath main body by sealing welding, and then performing degassing-sealing step;

preferably, in the sealing welding process of the top end cover and the metal sheath main body, high-purity argon is introduced to the degassing pipeline I through the degassing pipeline II;

preferably, in the degassing-sealing step, the degassing pipeline I and the degassing pipeline II are connected with a molecular pump for high-temperature heating degassing, the vacuum leakage rate of the sheath tool is detected, and after the requirement is met, combustible gas heating packaging treatment is performed on the degassing pipeline I and the degassing pipeline II;

preferably, the mouths of the degassing pipeline I and the degassing pipeline II are plugged with fine wire meshes.

5. A homogeneous high B according to any one of claims 1 to 4₄B of C content₄The preparation method of the C/Al composite material is characterized in that the sintering comprises any one of hot isostatic pressing sintering or hot pressing sintering.

6. A homogeneous high B according to claim 5₄B of C content₄The preparation method of the C/Al composite material is characterized in that when the sintering is hot isostatic pressing sintering, the sintering atmosphere is argon, the sintering temperature in the first step is 100-600 ℃, and the sintering temperature in the second step is 700-1200 ℃;

or/and the sintering pressure of the first step is 50MPa-150 MPa; the sintering pressure of the second step is 20MPa-80 MPa.

7. A homogeneous high B according to claim 6₄B of C content₄The preparation method of the C/Al composite material is characterized in that during hot isostatic pressing sintering, the sintering atmosphere is argon,

preferably, the temperature rise rate of the sintering temperature in the first step is 50-600 ℃/h, and the heat preservation time is 0.5-20 min;

preferably, the heating rate of the second step of sintering is 100-500 ℃/h, and the heat preservation time is 0.5-60 min.

8. A homogeneous high B according to claim 5₄B of C content₄The preparation method of the C/Al composite material is characterized in that when the sintering is hot-pressing sintering, the sintering temperature of the first step is 100-650 ℃, the sintering temperature of the second step is 750-1200 ℃,

or/and the pressure of the first step sintering is 50MPa-150 MPa; the pressure of the second step of sintering is 30MPa-100 MPa.

9. A homogeneous high B according to claim 8₄B of C content₄The preparation method of the C/Al composite material is characterized in that during hot-pressing sintering, the sintering atmosphere is argon or vacuum,

preferably, the heating rate of the first-step sintering is 100 ℃/h-1000 ℃/h, and the heat preservation time is 0.5min-30 min;

preferably, the heating rate of the second step of sintering is 100-800 ℃/h, and the heat preservation time is 5-60 min.

10. Homogeneous high B prepared by the method of any one of claims 1 to 9₄B of C content₄C/Al composite material.

Technical Field

The invention belongs to the technical field of powder metallurgy and materials, relates to the field of nuclear protection materials (spent fuel post-treatment and medical radioactive diagnosis and treatment scenes) and bullet-resistant materials in light armor protection parts, and particularly relates to a homogeneous high-B material₄B of C content₄A preparation method of a C/Al composite material.

Background

B₄The C/Al composite material has the advantages of high strength, high hardness, light material, good stability and the like, so that the C/Al composite material can be applied to the fields of nuclear protection, light armor protection and the like. In thatB₄In the C/Al, the Al content is,¹⁰b is a functional element for thermal neutron absorption, which generates (n, α) nuclear reaction to produce Li and He after capturing thermal neutrons, and the reaction is:¹⁰B+¹n→⁷Li+⁴He+2.6MeV。B₄c is required as a main body of the ballistic resistant material, and the content thereof is usually more than 50% (volume fraction). Thus, with B₄C is a matrix, and high B is developed₄B of C content₄C/Al composite material, B can be reduced₄C/Al is used as the design size of the nuclear protection product and meets the requirement of B₄C/Al is taken as the component requirement of the elastic-resistant material.

However, in B₄In the C/Al composite material, B is added₄C has a high melting point (2450 ℃), a high covalent bond content (about 93%) and a low fracture toughness (about 2-3 MPa. m)^1/2) The self-diffusion coefficient is low and the grain boundary movement resistance is large, so that the B content is high₄B of C content₄Sintering densification of C/Al composites is a difficult point.

Thus, a homogeneous high B is provided₄B of C content₄The preparation method of C/Al solves the problem of high B in the prior art₄B of C content₄The problem that the C/Al composite material is difficult to sinter and densify becomes a problem to be solved by the technical personnel in the field.

Disclosure of Invention

It is an object of the present invention to provide a homogeneous high B₄B of C content₄The preparation method of the C/Al composite material solves the problem of high B in the prior art₄B of C content₄The C/Al composite material is difficult to sinter and densify.

The second object of the present invention is to provide a homogeneous high B produced by the method₄B of C content₄C/Al composite material.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the preparation method of the homogeneous B4C/Al composite material with high B4C content comprises the following steps: b in powder state is mixed according to the volume ratio required by design₄The C raw material and the cast ingot Al raw material are sequentially loaded into a degassing sheath tool for degassing-packaging treatment, and then externally applied with forceSintering in two steps under the action of field assistance, wherein the sintering temperature T in the first step_ILower than the melting point of the Al raw material; second step sintering temperature T_IIHigher than the melting point of the Al raw material; force field F applied during the first sintering step_ILarger than the force field F applied in the second sintering step_II。

The invention adopts two-step sintering, the first step sintering is carried out below the melting point of Al raw material and a force field is applied, so that B₄Forming the powder C into powder B₄C, prefabricating a blank, wherein the Al raw material still keeps a compact solid state; and a second step of sintering: continuously raising the temperature to be above the melting point of the Al raw material, continuously applying a force field to melt the Al raw material to form a liquid phase, and infiltrating B₄C in the pores of the prefabricated blank body, and finally finishing B₄Densification of the C/Al composite material.

The two-step sintering method effectively overcomes the problems of one-step sintering. If the pressure is always applied during the sintering process during one-step sintering, B₄C always presents a densification trend, and molten aluminum liquid cannot effectively permeate B₄C in pores; if the pressure is applied only in the early stage of sintering and not applied in the later stage, the efficiency is greatly reduced. The Al raw material of the invention adopts an ingot casting state, namely a compact block material. Other typical forms of Al raw material such as Al powder. A layer of alumina is usually arranged on the surface of the Al material, and the smaller the particle size is, the larger the specific surface area is, and the higher the alumina content is; whereas the melting point of alumina is significantly higher than that of Al. Therefore, the Al raw material is in an ingot state, and under the same volume ratio, the content of alumina can be obviously reduced, thereby reducing the sintering temperature of the first step, improving the sintering period and reducing the energy consumption.

The invention carries out two-step sintering under the auxiliary action of an external force field. The present invention surprisingly found that the first step B is a step B if no external field is applied₄The powder C is in a loose powder state and cannot form physical occlusion, so that uniform pores are formed. And in the second step, under the action of continuous external force, the penetration of molten aluminum into the molten aluminum B can be improved dynamically₄C efficiency in pores. Therefore, the invention forms homogeneous B by sintering in two steps under the assistance of an external force field₄C-Al。

The inventionMiddle F_IGreater than F_II. After a great deal of experiments, the invention discovers that if F is carried out after creative labor_IIGreater than or equal to F_II.e. B₄C will continue to densify, the porosity will further decrease, the molten aluminum in the second step infiltrates to B₄The amount of C voids will be greatly reduced, resulting in a final state B₄The Al content in C-Al is far less than the designed volume ratio. Thus, design F of the present invention_II＜F_I。

The method can realize the rapid preparation of the high B through one-time densification₄B of C content₄C/Al three-dimensional net structure composite material. In preparation of B₄In the C/Al composite material, B₄C is a matrix, Al is a continuous distribution second phase, and Al is continuously distributed in a net shape on B₄Microstructure of the C matrix. High B₄The matrix with C content can reinforce B₄The C/Al is used as the neutron absorption rate of the neutron absorption composite material, so that the design size of the material is further reduced; the continuously distributed Al phase can effectively block B₄C matrix crack initiation and propagation, increasing B₄C/Al is used as the fracture toughness of the elastic-resistant material. In particular, Al phase in B₄C a main heat channel formed in the substrate and also has an improvement of B₄Thermal properties of the C/Al composite. The invention can quickly and efficiently obtain the homogeneous B with excellent mechanical and thermal properties₄C/Al composite material. B prepared by the invention₄The C/Al composite material can be used as an anti-bullet material in a light armor protection part and a radiation protection product material in spent fuel post-treatment and medical radioactive diagnosis and treatment scenes, and has a good application prospect.

In some embodiments of the invention, B₄The particle size range of the raw material C is 0.1-100 mu m; or/and the Al raw material comprises pure aluminum or an aluminum alloy.

B₄The raw material powder C has a single grain size or consists of different grain size compositions.

In some embodiments of the invention, B₄The volume ratio of the C raw material to the Al raw material is more than or equal to 1;

preferably 1, 1.5 or 1.2.

In some embodiments of the invention, the degassing sheath tool is a double-degassing sheath tool, and comprises a metal sheath main body, a top end cover and a bottom end cover, wherein a degassing pipeline I is arranged on the top end cover, and a degassing pipeline II is arranged on the bottom end cover;

after the bottom end cover, the degassing pipeline II and the metal sheath main body are sealed, B is added₄C raw material and Al raw material; sealing the top end cover and the metal sheath main body by sealing welding, and then performing degassing-sealing step;

preferably, in the sealing welding process of the top end cover and the metal sheath main body, high-purity argon is introduced to the degassing pipeline I through the degassing pipeline II;

preferably, in the degassing-sealing step, the degassing pipeline I and the degassing pipeline II are connected with a molecular pump for high-temperature heating degassing, the vacuum leakage rate of the sheath tool is detected, and after the requirement is met, combustible gas heating packaging treatment is performed on the degassing pipeline I and the degassing pipeline II;

preferably, the mouths of the degassing pipeline I and the degassing pipeline II are plugged with fine wire meshes.

According to the invention, the degassing pipeline I and the degassing pipeline II are arranged, high-purity argon is introduced to the degassing pipeline I through the degassing pipeline II in the sealing welding process of the top end cover and the metal sheath main body, and a flowing inert gas area is formed in the metal sheath main body, so that high-temperature oxidation of raw materials and the metal sheath in the sealing welding process can be prevented. During the subsequent degassing-sealing step, due to the design of double degassing pipelines, the top end cover and the bottom end cover are both provided with degassing pipelines, so that the degassing time can be effectively reduced, and the degassing efficiency is improved.

According to the invention, the metal wire meshes are arranged at the pipe orifices of the gas pipeline I and the gas removal pipeline II, so that powder is effectively prevented from escaping from the gas removal pipeline, and meanwhile, the smooth passing of gas flow is ensured.

In some embodiments of the invention, the degassing temperature is 200-^-2-1.0×10^-4Pa, vacuum leak rate of the sheath of 5 multiplied by 10^-6-1.0×10^-9Pa·m³·s^-1。

In some embodiments of the invention, the sheath is made of Fe and comprises low carbon steel, high carbon steel or stainless steel, and the thickness of the sheath is 0.5-5 mm.

B in the invention₄The raw material C, the raw material Al and the sheath are subjected to surface impurity removal and purification treatment.

In some embodiments of the invention, the sintering comprises any one of hot isostatic pressing or hot pressing.

In some embodiments of the invention, when the sintering is hot isostatic pressing sintering, the sintering atmosphere is argon, the temperature of the first sintering step is 100-600 ℃, and the temperature of the second sintering step is 700-1200 ℃;

or/and the sintering pressure of the first step is 50MPa-150 MPa; the sintering pressure of the second step is 20MPa-80 MPa.

In some embodiments of the present invention, the sintering atmosphere during hot isostatic pressing sintering is argon,

preferably, the temperature rise rate of the sintering temperature in the first step is 50-600 ℃/h, and the heat preservation time is 0.5-20 min;

preferably, the heating rate of the second step of sintering is 100-500 ℃/h, and the heat preservation time is 0.5-60 min.

In some embodiments of the invention, when the sintering is hot-pressing sintering, the temperature of the first sintering step is 100-650 ℃, the temperature of the second sintering step is 750-1200 ℃,

or/and the pressure of the first step sintering is 50MPa-150 MPa; the pressure of the second step of sintering is 30MPa-100 MPa.

In some embodiments of the invention, during hot-pressing sintering, the sintering atmosphere is argon or vacuum,

preferably, the heating rate of the first-step sintering is 100 ℃/h-1000 ℃/h, and the heat preservation time is 0.5min-30 min;

preferably, the heating rate of the second step of sintering is 100-800 ℃/h, and the heat preservation time is 5-60 min.

In some embodiments of the invention, the method further comprises a step of demolding treatment, namely B after two-step sintering densification₄Demoulding the C/Al composite material to obtain B₄C/Al composite material sample.

The homogeneous high B prepared by the method of the invention₄B of C content₄C/Al composite material.

In some embodiments of the invention, the method comprises the following steps:

(1) b is to be₄C powder, ingot-state Al raw material and a metal sheath are respectively subjected to surface impurity removal and purification treatment. After the bottom end of the metal sheath is sealed with the end cover by sealing welding, the B is put into the metal sheath₄C and Al are sequentially filled into the metal sheath.

(2) The component B prepared in the step (1) contains₄And sealing the metal sheath of the C/Al mixture and the top end cover by sealing and welding. The top degassing pipe is connected with the molecular pump, high-temperature heating degassing is carried out, the vacuum leakage rate of the sheath is detected, and after the requirement is met, combustible gas heating packaging treatment is carried out on the degassing pipe at the top end of the sheath. Wherein, the degassing pipe is reserved in the bottom end cover and the top end cover of the metal sheath, and a fine metal wire mesh is additionally plugged at the mouth of the degassing pipe. And in the sealing and welding process of the metal sheath and the top end cover, introducing high-purity argon through the degassing pipe at the bottom end cover so as to prevent the high-temperature oxidation of the raw materials and the metal sheath in the sealing and welding process. The top degassing pipe is connected with a molecular pump for high-temperature heating degassing, wherein the degassing temperature is 200-^-2-1.0×10^-4Pa. The vacuum leak rate of the sheath is 5 multiplied by 10^-6-1.0×10^-9Pa·m³·s^-1。

(3) Two-step sintering: the sintering mode is any one of hot isostatic pressing sintering and hot pressing sintering;

when the sintering mode is hot isostatic pressing sintering, the sintering atmosphere is argon, the temperature of the first-step sintering is 100-600 ℃, the pressure is 50-150 MPa, the heating rate is 50-600 ℃/h, and the heat preservation time is 0.5-20 min; the temperature of the second step of sintering is 700-1200 ℃, the pressure is 20-80 MPa, the heating rate is 100-500 ℃/h, and the heat preservation time is 0.5-60 min.

The sintering mode is hot-pressing sintering, the sintering atmosphere is argon or vacuum, the sintering temperature in the first step is 100-650 ℃, the pressure is 50-150 MPa, the heating rate is 100-1000 ℃/h, and the heat preservation time is 0.5-30 min; the temperature of the second step of sintering is 750-1200 ℃, the pressure is 30-100 MPa, the heating rate is 100-800 ℃/h, and the heat preservation time is 5-60 min.

Compared with the prior art, the invention has the following beneficial effects:

1. the process of mixing materials is not needed, and Al and B can be avoided₄The powder C can cause possible uneven components in the mixing process; can effectively avoid Al and B in the process₄The C powder is oxidized to generate Al in the ball milling process₂O₃And B₂O₃Oxide impurities such that Al-B₄The unclean interface of C leads to the risk that cracks are easy to nucleate and grow in the preparation process, and the performance of the material is deteriorated.

2. The press forming process is not needed, the introduction of secondary auxiliary materials such as adhesive, forming agent and the like in the process is avoided, and B is avoided₄C is difficult to be pressed and formed.

3. The process is controllable: by regulating the first sintering process, different densities B can be realized₄And C, controllable preparation of the prefabricated body. By regulating the second sintering process, high B content can be realized₄C content B₄Controllable preparation of the C/Al composite material.

4. Because the external force field is uniformly applied while the temperature is raised, the heat preservation time can be shortened while the temperature is raised, and compact B is obtained₄C/Al composite material. In reducing Al and B₄The wetting angle of C is simultaneously weakened by Al-B₄The degree of interfacial reaction of C, and can effectively avoid the risk of local stress concentration, and obtain the product with excellent performance.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention.

FIG. 2 is a schematic view of the design of a degassing sheath tool.

FIG. 3 shows the position B of the double de-airing tube after being packaged₄C/Al physical diagram.

FIG. 4 is B₄Microstructure of C/Al composite material.

Detailed Description

All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.

Any feature disclosed in this specification may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.

Example 1

This example discloses the homogeneous high B of the present invention₄B of C content₄The preparation method of the C/Al composite material is shown in the attached drawing 1 in the process flow diagram, and the degassing sheath tool is shown in the attached drawing 2 in the process flow diagram.

The gas removal canning frock is two gas removal canning frock, including metal canning main part, top lid and bottom lid, be provided with gas removal pipeline I on the top lid, the bottom lid is provided with gas removal pipeline II. And the mouths of the degassing pipeline I and the degassing pipeline II are plugged with fine metal wire nets.

The preparation method of the embodiment comprises the following specific steps:

(1) b is to be₄C, performing surface impurity removal and purification treatment on the raw material C, the raw material Al and the sheath; after the metal sheath main body is sealed with the bottom end cover and the degassing pipeline II, pressing B₄C raw material/Al raw material (volume ratio) 1, and B₄And sequentially loading the C raw material and the Al raw material into the metal sheath main body.

Wherein B is₄The raw material C is in a powder state, and the average grain diameter is 3 mu m; the Al raw material is compact pure aluminum ingot; the sheath is made of low carbon steel with the thickness of 2 mm.

(2) The component B prepared in the step (1) contains₄And sealing the metal sheath main body of the C/Al mixture and the top end cover by sealing and welding. And in the sealing and welding process of the metal sheath main body and the top end cover, introducing high-purity argon to the degassing pipeline I through the degassing pipeline II so as to prevent high-temperature oxidation of the raw materials and the metal sheath in the sealing and welding process. Then degassing and sealing, connecting a degassing pipeline I and a degassing pipeline II with a molecular pump, and heating at high temperature for degassing, wherein the degassing temperature is 400 ℃, the heat preservation time is 3 hours, and the vacuum degree is 5 multiplied by 10^-3Pa, vacuum leak rate of the sheath of 5 multiplied by 10^-8Pa·m³·s^-1. And after the degassing is finished, heating and packaging the combustible gas for the degassing pipeline I and the degassing pipeline II. B packaged by double degassing tube sheathing tool₄The C/Al samples are shown in FIG. 3.

(3) Two-step sintering

Packaging the B subjected to the wrapping and packaging treatment in the step (2)₄And (3) carrying out two-step sintering densification on the C/Al mixture, wherein the sintering mode is hot isostatic pressing sintering, and the sintering atmosphere is argon.

Sintering in the first step: sintering below the melting point of Al and applying a force field such that B₄Forming the powder C into powder B₄C prefabricating a blank, keeping Al in a compact solid state, and sintering at a temperature T_IAt 500 ℃ under a pressure F_IThe temperature rise rate is 250 ℃/h, and the heat preservation time is 0.5min under 80 MPa;

and a second step of sintering: the temperature is continuously raised above the melting point of Al and the force field (F) is continuously applied_II，F_II＜F_I) Melting Al to form a liquid phase, impregnating B₄C in the pores of the prefabricated blank body, the sintering temperature T_IIAt 950 ℃ under a pressure F_II50MPa, the heating rate is 200 ℃/h, and the heat preservation time is 30 min. Finish B₄Densification of the C/Al composite material.

(4) Mold release treatment

B after two-step sintering densification in the step (3)₄Demoulding the C/Al composite material to obtain B₄The density of the sample of the C/Al composite material is 99.98 percent TD. The microstructure of the resulting sample is shown in FIG. 4. As can be seen from FIG. 4, B of the present embodiment₄In the C/Al composite material, B₄C is a matrix (dark color region, dispersed particle state), Al is a continuously distributed second phase (light color region, continuously distributed state), and Al is continuously distributed in a net shape in the B₄Microstructure of the C matrix.

Example 2

This example discloses the homogeneous high B of the present invention₄B of C content₄Compared with the embodiment 1, the preparation method of the C/Al composite material has the following specific parameters:

1. in step (1), B₄C raw material/Al raw material (volume ratio) 1.5;

wherein B is₄The raw material C is in a powder state and consists of powder with the average grain diameter of 0.5 mu m and 5 mu m according to the volume ratio of 1: 1; the Al raw material is compact pure aluminum ingot; the sheath is low-carbon steel with the thickness of 3 mm.

2. In the step (2), the degassing temperature is 300 ℃, the heat preservation time is 4 hours, and the vacuum degree is 1 multiplied by 10^-3Pa. The vacuum leak rate of the sheath is 1 multiplied by 10^-8Pa·m³·s^-1。

3. In the step 3, the sintering mode is hot isostatic pressing sintering, and the sintering atmosphere is argon.

Sintering in the first step: sintering temperature T_IAt 200 ℃ under a pressure F_IThe temperature is 150MPa, the heating rate is 500 ℃/h, and the heat preservation time is 5 min;

and a second step of sintering: sintering temperature T_IIAt 1200 ℃ under a pressure F_II50MPa, the heating rate is 400 ℃/h, and the heat preservation time is 15 min.

B finally obtained in this example₄The density of the C/Al composite sample piece is 99.97 percent TD.

Example 3

This example discloses the homogeneous high B of the present invention₄B of C content₄Compared with the embodiment 1, the preparation method of the C/Al composite material has the following specific parameters:

1. in step (1), B₄C raw material/Al raw material (volume ratio) 1.2;

wherein B is₄The average grain diameter of the raw material powder is 20 mu m; the Al raw material is compact pure aluminum ingot; the sheath is made of low carbon steel with the thickness of 2 mm.

2. In step 2, degassing temperature is 250 ℃, heat preservation time is 4h, and vacuum degree is 1.0 multiplied by 10^-4Pa. The vacuum leak rate of the sheath is 1 multiplied by 10^-9Pa·m³·s^-1。

(3) In the step 3, the sintering mode is hot isostatic pressing sintering, and the sintering atmosphere is argon.

Sintering in the first step: sintering temperature T_IAt 100 ℃ under a pressure F_IThe temperature is 120MPa, the heating rate is 600 ℃/h, and the heat preservation time is 20 min;

and a second step of sintering: sinteringTemperature T_IIAt 700 ℃ under a pressure F_IIThe temperature rise rate is 500 ℃/h, and the heat preservation time is 60min under 20 MPa.

(4) Mold release treatment

B finally obtained in this example₄The density of the C/Al composite sample piece is 99.95% TD.

The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.