CN108558427A - A method of preparing even density carbon/carbon composite tablet using confinement reactor batch - Google Patents

Abstract

The invention discloses a kind of methods preparing even density carbon/carbon composite tablet using confinement reactor batch.The confinement reactor, including gas pretreatment device, gas collecting apparatus, precipitation equipment；The precipitation equipment includes m block air dividing plates, 1 group of outer barrel, m side plate；This method is to be positioned over carbon fiber tablet precast body in the deposition chambers being made of m blocks air dividing plate and 1 group of side plate of m with erect form, deposition chambers are further divided into several narrow domain reaction compartments, ensure that carbon fiber tablet precast body is erected in the clear area of m block air dividing plates simultaneously, air-flow will not be formed and be obstructed so that air-flow can be realized and is uniformly distributed.Present invention process method is simple and convenient to operate, carbon-source gas utilization rate is high, process cycle is short, and gained monomer carbon/carbon composite tablet volume density uniformity is less than ± 0.05g/cm³。

Description

Batch preparation of carbon/carbon composite flat plates with uniform density using confinement reactor Methods

technical field

The invention belongs to the field of carbon/carbon composite materials, and in particular relates to a method for batch-preparing carbon/carbon composite material plates with uniform density by using a confining reactor.

Background technique

Carbon/carbon composite material is carbon fiber reinforced carbon matrix composite material, which has low density, high specific strength ratio, low thermal expansion coefficient, high thermal and electrical conductivity, creep resistance, thermal shock resistance, ablation resistance and good performance under non-oxidizing medium conditions. Excellent properties such as high temperature mechanical properties and dimensional stability are related to the development of China's strategic industries and national security, and support the integration of new structures and functions of major national science and technology projects such as advanced aircraft engineering, large aircraft engineering, manned spaceflight and lunar exploration projects. Key core materials play a unique supporting role in the future development of China's aerospace equipment, rail transit equipment and other advantageous industries, aviation equipment, automobiles, nuclear industries and other strategic industries, as well as key weapons and equipment.

Chemical vapor deposition is the preferred method for preparing high-performance carbon/carbon composites. The carbon/carbon composites prepared by this method have the advantages of adjustable matrix carbon structure, tight combination with carbon fibers, and uniform and dense material structure. At present, there are many preparation processes for carbon/carbon composite flat plates, but due to the difficulty in controlling the gas flow field, the densification uniformity of the single carbon/carbon flat plate components is poor, and in the batch production process, the bulk density difference between individuals Larger, not conducive to stable product performance.

Especially for a thick-walled flat plate with a thickness ≥ 25mm, in the deposition process of the prior art, the phenomenon of closed cells also occurs, which makes the density gradient of the product in the thick-wall direction large.

In order to realize the stability and production efficiency of mass production of carbon/carbon composite plate components, it is necessary to carefully design the tooling to achieve effective regulation of the reaction gas flow field, and to supplement the design and implementation of chemical vapor deposition process to solve the problem of flat carbon/carbon composite materials. The bottleneck problem of long preparation period and poor stability can be solved, and the utilization rate of carbon source gas raw materials can be improved, and the manufacturing cost can be reduced.

Contents of the invention

Aiming at the deficiencies of the prior art, the object of the present invention is to provide a method for batch-preparing carbon/carbon composite flat plates with uniform density using a confinement reactor.

To achieve the above object, the present invention provides the following technical solutions:

A method for batch-preparing carbon/carbon composite flat panels with uniform density using a confinement reactor,

The confinement reactor includes a gas pretreatment device, a gas collection device, and a deposition device; the gas pretreatment device is located at the bottom of the confinement reactor, the gas collection device is located at the top of the confinement reactor, and the deposition device is located at the confinement reaction the middle of the device;

The deposition device includes m gas distribution plates, an outer cylinder, and m-1 groups of side plates; the m≥2;

There are n groups of air holes arranged at intervals on any one of the gas distribution plates, said n≥2, and the distance between any adjacent two groups of air holes is 10-100mm; n-1 blank areas are formed between the n groups of air holes;

The m gas distribution plates are arranged sequentially from bottom to top along the radial direction of the outer cylinder;

The m-1 groups of side plates are arranged inside the outer cylinder, any group of side plates is vertically arranged between any two adjacent gas distribution plates, and surrounds the air holes in the gas distribution plates;

The m gas distribution plates and the m-1 group of side plates divide the deposition device into m-1 deposition chambers; from the bottom to at least the first deposition chamber, the second deposition chamber, and so on to the first m-1 deposition chambers; wherein the first gas distribution plate forms the bottom of the first deposition chamber, and the m-th gas distribution plate forms the top of the m-1 deposition chamber;

The method for preparing flat carbon/carbon composite materials with uniform density in batches by using the above-mentioned confined reactor comprises the following steps:

1), Confinement reactor charging

Load the first group of not more than n-1 carbon fiber flat plate preforms upright on the first gas distribution plate; and ensure that any piece of carbon fiber flat prefabricated body is erected on the blank area of the first gas distribution plate; then place the second The gas distribution plate is installed on the top of the first group of carbon fiber flat prefabricated body and fixed on the outer cylinder, and ensure that the blank area in the second gas distribution plate is directly above the blank area of the first gas distribution plate, and install the second gas distribution plate at the same time 1 set of side plates, ensuring that it surrounds the air holes in the first gas distribution plate; that is, to complete the loading of the first deposition chamber, and complete the loading of the remaining m-2 deposition chambers from bottom to top in the same way material;

2), chemical vapor deposition

After the loading is completed, carry out the first chemical vapor deposition on the carbon fiber flat plate prefabricated body, cool down, and unload to obtain a deposited carbon fiber flat plate preformed body;

3), repeat charging and deposition to the required density

Continue to repeat the charging and chemical vapor deposition of the primary deposition preform until the volume density of the flat carbon/carbon composite material is 1.2-1.75g/cm ³ ;

During the charging process, the latter charging is carried out in the reverse order of the deposition chamber of the previous charging, and during the charging process, any piece of deposited carbon fiber flat plate prefabricated The radial flip of the domain reactor is 180°.

In the present invention, the fact that the blank area in the second gas distribution plate is directly above the blank area of the first gas distribution plate means that when the two gas distribution plates move radially, the blank areas can completely overlap.

In the present invention, the specific manner of the reverse order charging of the deposition chambers is: when m-1 deposition chambers are even, the deposition chambers are divided into m-1/2 groups, wherein the sum is m The two groups of preforms in the two deposition chambers of , during the next loading process, the spatial positions are reversed; when the number of m-1 deposition chambers is odd, the preforms in the middle deposition chamber are still installed in the deposition chamber In the chamber, the remaining m-2 deposition chambers are divided into m-2/2 groups, and the two groups of prefabricated bodies in the two deposition chambers whose sum is m, in the next charging process, the spatial positions are reversed;

For example, when m-1 is 4, the flat plate preform that was loaded in the first deposition chamber before will be loaded in the fourth deposition chamber during the next loading process.

In a preferred solution, the thickness of the carbon fiber flat plate prefabricated body is 25-80 mm. It adopts the direct loading method when it is installed vertically.

In a preferred solution, the thickness of the carbon fiber flat plate prefabricated body is 6-25 mm, and it is loaded vertically by two pieces of graphite tooling.

In the preferred solution, through holes are evenly arranged in the middle of the graphite tooling, and fastening structures are installed on the edges. The area of the graphite tooling is larger than the area of the carbon fiber flat plate prefabricated body, and after the carbon fiber flat plate prefabricated body is clamped, the carbon fiber flat plate is prefabricated. The body is wrapped in the through-hole area of the graphite tooling. In the present invention, the thin-walled plates with a thickness of 6-25mm are clamped by the tooling, which can effectively ensure the straightness of such plates.

In a preferred solution, the thickness of the graphite tooling is 6-15 mm.

In a preferred solution, the distance between adjacent carbon fiber flat plate prefabricated bodies loaded vertically is 20-60 mm.

In the technical solution of the present invention, the carbon fiber flat plate prefabricated body is vertically loaded on the blank area of the gas distribution plate, which will not form a barrier to the air flow, so that the air flow can be evenly distributed, and in any deposition chamber, by no more than n-1 The vertically arranged carbon fiber flat prefabricated body divides the deposition chamber into several slit channels to form a narrow deposition space. The reaction gas in the space flows along the surface of the flat flat prefabricated body in the narrow deposition space, which can greatly The effective utilization rate of the gas is increased, and the uniformity of the gas on the surface of the carbon fiber flat plate prefabricated body is further ensured.

In the technical solution of the present invention, any deposition chamber is separated by two adjacent gas distribution plates, and the m-2 gas distribution plates placed in the middle of the deposition device can serve as a barrier to the next deposition chamber. The outgassing function can also play a guiding role for the previous deposition chamber; this can ensure the uniformity of the reaction gas flow field in any deposition chamber.

In the preferred solution, the layout of any two gas distribution plates is the same.

In a preferred solution, the gas distribution plate is provided with a bayonet and connected with the outer cylinder.

In a preferred scheme, the m is 2-8.

In a preferred solution, the distance between any two adjacent gas distribution plates in the vertical direction is 100-1000.

In a preferred solution, any group of pores on the gas distributor plate consists of 2-3 rows of closely arranged pores, the diameter of any one of the pores is 8-12 mm, and the n is 3-8.

In a preferred solution, the distance between any two adjacent groups of pores is 25-90mm;

In a preferred solution, the gas pretreatment device is composed of a gas distribution cap and a cylinder, the gas distribution cap is located at the bottom center of the cylinder, and several gas distribution holes are uniformly arranged on the top and side walls of the cylinder for feeding the confinement reactor The air flow is evenly distributed inside, and the height of the cylinder is greater than the height of the gas distribution cap.

As a further preference, the thickness and diameter of the cylinder and the outer cylinder are equal.

In a preferred solution, the gas collecting device is a cone-shaped cylinder with openings at both ends.

As a further preference, the inner diameter of the bottom end of the gas collecting device is equal to that of the outer cylinder, and the thickness is ≤ the thickness of the outer cylinder.

In a preferred solution, the arbitrary group of side plates is composed of 4 side plates, and the m gas distribution plates and m-1 sets of side plates divide the deposition device into m-1 square deposition chambers.

In a preferred scheme, the confined reactor is made of carbonaceous material. As a further preference, the confined reactor is at least one of graphite, carbon/carbon composite material, and hard felt.

In a preferred solution, the carbon fiber flat preform is selected from at least one of flat carbon felt, integral needle felt, finely punctured preform, and carbon cloth stitched preform.

In a preferred solution, the apparent density of the carbon fiber plate preform is 0.15-1.0 g/cm ³ .

In a preferred solution, the carbon fiber flat preform is first pretreated, and the pretreatment process is that the carbon fiber flat preform is placed in a high-temperature graphitization furnace for heat treatment at 1600-2000° C. under the protection of an inert atmosphere.

As a further preference, the temperature of the heat treatment is 1800-2000°C, and the time of the heat treatment is 1-2 hours.

In a preferred solution, the confinement reactor is placed in a vapor deposition furnace, and the gas distribution cap is connected with an air inlet pipeline in the vapor deposition furnace.

During the vapor deposition process, the carbon source gas and dilution gas enter the gas distribution cap from the intake pipe, and then the gas distribution cap diffuses the gas evenly into the cylinder, and the carbon source gas and dilution gas entering in the cold state are processed. Mixing and preheating, and then guide the flow by the gas distribution plate located at the bottom of the deposition device, so that it enters the deposition device evenly for reaction, and the waste gas formed after the reaction is discharged from the furnace body by the gas collection device to avoid retention of harmful substances such as carbon black .

In the present invention, an isothermal chemical vapor deposition method is used to carry out stage cycle densification on the flat plate prefabricated body.

In a preferred solution, the carbon source gas is propylene (C ₃ H ₆ ), the diluent gas is nitrogen (N ₂ ), and the flow ratio of propylene to nitrogen is (1-4):1; preferably (3-4 ):1.

In a preferred scheme, the temperature of the chemical vapor deposition is 900-1000°C, preferably 930-960°C.

In a preferred scheme, the pressure of the chemical vapor deposition is 0.6-1.2 kPa, preferably 0.6-1.0 kPa.

In a preferred scheme, the time for each chemical vapor deposition is 40-120 hours, preferably 50-100 hours.

In the present invention, the chemical vapor deposition densification time of the flat carbon fiber preform is 200-400 hours, the volume density of the obtained flat carbon/carbon composite material is 1.2-1.75g/cm ³ , and the volume of the prepared single carbon/carbon composite flat plate The density uniformity is less than ±0.05g/cm ³ .

The flat carbon/carbon composite material obtained in the present invention can be directly used as a flat plate member of the carbon/carbon composite material, and can also be used to prepare a high-performance carbon/ceramic composite material by introducing a ceramic phase in a later stage.

The present invention adopts above-mentioned method, has following advantage and effect:

(1) Confined reactors are built with full carbon tooling, which can effectively control the reaction gas flow field, ensure the uniformity and stability of the gas flow field and thermal field, and design the narrow-area deposition space, so that the reaction gas in the space is deposited in the narrow area Flowing along the surface of the flat plate preform in the space can ensure the uniformity of the gas on the surface of the carbon fiber flat preform.

(2) The loading mode of multiple deposition chambers is adopted. Under the vertical loading condition of the flat plate prefabricated body in each deposition chamber, it does not bear the pressure of the upper flat flat prefabricated body and tooling, which can reduce the thermal deformation of the flat plate prefabricated body and effectively ensure the carbon/carbon composite material flatness of the plate.

(3) The staged deposition process and periodic loading method can shorten the densification cycle of the flat plate preform and ensure the densification uniformity of the single carbon/carbon composite flat plate.

(4) The low-temperature and low-pressure chemical vapor deposition process is suitable for the preparation of porous carbon/carbon composite materials, and can be used to introduce ceramic phases to prepare high-performance carbon/ceramic composite materials; it can also avoid premature sealing of the surface of the flat plate prefabricated body, thereby It improves the densification efficiency and is suitable for batch preparation of high-density carbon/carbon composite flat plates.

In summary, the present invention provides a uniform gas-phase densification method for a carbon/carbon composite flat plate, which has the advantages of simple process, convenient operation, large loading capacity, high utilization rate of carbon source gas, and short process cycle, and the obtained monomer carbon/carbon The volume density uniformity of the composite plate is less than ±0.05g/cm ³ , which is suitable for batch preparation of porous carbon/carbon composite body, and for the introduction of ceramic phase in the later stage to prepare high-performance carbon/ceramic composite materials; it is also suitable for batch preparation of high Density carbon/carbon composites provide a practical and effective method for high-efficiency densification and low-cost production of carbon/carbon composite plates.

Description of drawings

Fig. 1 is a schematic diagram of loading a confinement reactor and a flat panel preform of the present invention;

In the drawings, 1 gas pretreatment device, 11 gas distribution cap, 12 cylinder, 2 deposition device, 21 gas distribution plate, 22 side plate, 23 outer cylinder, 3 gas collection device.

Figure 2 is a schematic diagram of the gas distribution plate.

Fig. 3 is a schematic diagram of clamping and loading of graphite tooling for flat plate preforms with a thickness in the range of 6-25 mm.

Detailed ways

The method for uniform gas-phase densification of the carbon/carbon composite flat plate of the present invention will be further described in detail below in conjunction with specific examples. It should be understood that the following examples are only for illustrating and explaining the present invention, and should not be construed as limiting the protection scope of the present invention. All technologies realized based on the above contents of the present invention are covered within the scope of protection intended by the present invention.

Unless otherwise specified, the raw materials used in the following examples are commercially available or can be prepared by known methods.

Example 1

Uniform vapor phase densification method of carbon/carbon composite flat plate:

(1) Place the carbon fiber integral needle-punched felt with a size of 350×350×30mm and an apparent density of 0.46g/ ^cm3 in a high-temperature graphitization furnace, and heat-treat the carbon fiber preform at 1800°C under an argon protective atmosphere. 2 hours.

(2) Set up the confinement reactor according to the accompanying drawing 1, first place the gas distribution cap at the bottom center of the cylinder, then place the first gas distribution plate, and then place the first group of 4 carbon fiber flat plate prefabricated bodies in an upright form Load it directly on the first gas distribution plate, and ensure that any piece of carbon fiber flat plate prefabricated body stands upright on the blank area of the first gas distribution plate; then install the second gas distribution plate on top of the first group of carbon fiber flat plate prefabricated bodies And fix it on the outer cylinder, and ensure that the blank area in the second air distribution plate is directly above the blank area of the first air distribution plate, and at the same time install the first set of 4 side plates to ensure that it divides the first block The air holes in the gas plate surround it; that is, the filling of the first square deposition chamber is completed, and the filling of the remaining 3 deposition chambers is completed in the same way from bottom to top; bottom-up is defined as L1, L2, L3 , L4. Finally, the gas collection device is placed directly above the uppermost layer deposition chamber. Complete the installation of the confinement reactor, and place it in the chemical vapor deposition furnace, make the gas distribution cap communicate with the inlet pipe in the chemical vapor phase furnace,

In this embodiment, the air distribution plates with the same layout are adopted, and any air distribution plate is provided with 5 groups of air holes, and the distance between each group of air holes is 40mm, and the air hole area of the air distribution plate is densely packed. Two rows of Φ8mm air distribution holes, after the installation is completed, the distance between adjacent flat prefabricated bodies is 30mm.

(3) Using propylene as the carbon source gas and nitrogen as the diluent gas, the flow rate of propylene is 40L/min, and the flow rate of nitrogen is 10L/min. The isothermal chemical vapor deposition method is used for pyrolytic carbon densification, and the deposition temperature is 950°C. , the deposition pressure is 0.9-1.0kPa, and the deposition time of the first cycle is 100h.

(4) After unloading, reload the plate preforms in different deposition chambers from bottom to top in the order of L4, L3, L2, and L1, and at the same time turn the individual carbon/carbon composite plates along the radial direction of the confined reactor Rotate 180° for loading, and continue to deposit for 100 h under the deposition process conditions of the above step (3).

(5) The prepared carbon/carbon composite plate is subjected to high-temperature heat treatment at 2100° C. under an argon protective atmosphere to obtain a carbon/carbon porous body for carbon/ceramic composite materials. The volume density of the obtained batches of carbon/carbon composite material flat plates is between 1.32 and 1.38g/cm ³ , and the carbon/carbon composite material flat plates in different deposition chambers are sampled, and the uniformity of the monomer volume density is less than ±0.05g/cm3 ³ .

Example 2

Uniform vapor phase densification method of carbon/carbon composite flat plate:

(1) Continue to load the carbon/carbon composite material plates obtained in Example 1 according to the order of L1, L2, L3, and L4, and at the same time, rotate the individual carbon/carbon composite material plates by 180° for loading.

(2) Using propylene as the carbon source gas, nitrogen as the dilution gas, wherein the flow rate of propylene is 35L/min, and the flow rate of nitrogen is 10L/min, and the chemical vapor deposition method is used for pyrolytic carbon densification, and the deposition temperature is 950°C. The deposition pressure is 0.7-0.8kPa, and the deposition time is 100h.

(3) Carry out surface machining on the carbon/carbon composite material flat plate, load according to the order of L4, L3, L2, L1, and rotate the individual carbon/carbon composite material flat plate by 180° for loading, the above step (2) under the deposition process conditions Continue to deposit for 100h.

(4) Perform a high-temperature heat treatment at 2100° C. on the prepared carbon/carbon composite material flat plate under an argon protective atmosphere to obtain a carbon/carbon composite material flat plate. The bulk density of the carbon/carbon composite material plates in the obtained batches is between 1.64 and 1.68g/cm ³ , and the carbon/carbon composite material plates in different deposition chambers are sampled, and the uniformity of the monomer volume density is less than ±0.05g/cm3. cm ³ .

The tensile strength of batch carbon/carbon composite materials is 75-95MPa, the compressive strength is 85-100MPa, and the bending strength is 110-130MPa

Take one piece of carbon-carbon composite material with a density of 1.65g/cm ³ , and take 6 test blocks from different areas for mechanical performance testing. Among these 6 test blocks, there are carbon dioxide particles distributed in the central area and surface area in the thickness direction of the test block. The test block, its detection results are shown in Table 1:

Table 1 Mechanical properties of individual carbon-carbon composites tested in different regions

test block 2-1 2-2 2-3 2-4 2-5 2-6 density 1.64 1.68 1.66 1.66 1.65 1.67 Tensile Strength 80 88 81 81 79 86 compressive strength 90 97 92 90 90 95 Bending strength 115 115 122 119 116 123

Example 3

Uniform vapor phase densification method of carbon/carbon composite flat plate:

(1) Place the carbon cloth stitched preform with a size of 500×300×7mm and an apparent density of 0.98g/ ^cm3 in a high-temperature graphitization furnace, and heat-treat the carbon fiber preform at 2000°C under an argon protective atmosphere. Keep warm for 2 hours.

(2) Set up the confinement reactor according to the accompanying drawing 1, first place the gas distribution cap at the bottom center of the cylinder, then place the first gas distribution plate, and then use two pieces of graphite for the first group of 4 carbon fiber flat plate preforms The anti-deformation tooling is clamped and loaded on the first air distribution plate in an upright form, and any carbon fiber flat prefabricated body is guaranteed to stand upright on the blank area of the first air distribution plate; then the second air distribution plate is installed on the first air distribution plate The first set of carbon fiber flat plate prefabricated body is fixed on the outer cylinder, and the blank area in the second air distribution plate is ensured to be directly above the blank area of the first air distribution plate, and the first set of four side plates is installed at the same time , to ensure that it surrounds the air holes in the first gas distribution plate; that is, to complete the filling of the first square deposition chamber, and in the same way, complete the filling of the remaining two deposition chambers from bottom to top; from bottom to top The above is defined as L1, L2, L3. Finally, the gas collection device is placed directly above the uppermost layer deposition chamber. Complete the installation of the confinement reactor, and place it in the chemical vapor deposition furnace, make the gas distribution cap communicate with the inlet pipe in the chemical vapor phase furnace,

In this embodiment, the air distribution plates with the same layout are adopted, and any air distribution plate is provided with 5 groups of air holes, and the distance between each group of air holes is 45mm, and the air hole area of the air distribution plate is densely packed. For two rows of Φ10 gas distribution holes, the thickness of the two pieces of graphite tooling used is 8mm. After the installation is completed, the distance between adjacent flat plate prefabricated bodies is 60mm.

(3) Using propylene as the carbon source gas and nitrogen as the diluent gas, the flow rate of propylene is 30L/min, and the flow rate of nitrogen is 10L/min. The isothermal chemical vapor deposition method is used for pyrolytic carbon densification, and the deposition temperature is 930°C. , the deposition pressure is 0.6-0.8kPa, and the deposition time of the first cycle is 100h.

(4) The plate preforms in different deposition chambers are loaded from bottom to top in the order of L3, L2, and L1. At the same time, the individual carbon/carbon composite plates are loaded by flipping and rotating 180° along the radial direction of the confinement reactor, and the tooling is clamped state, continue to deposit for 100 h under the deposition process conditions of the above step (3).

(5) Carry out surface machining on the carbon/carbon composite plate, load it in the order of L1, L2, and L3, and at the same time, turn the individual carbon/carbon composite plate 180° along the radial direction of the confined reactor for loading. Using propylene as the carbon source gas and nitrogen as the dilution gas, the flow rate of propylene is 30L/min, and the flow rate of nitrogen is 10L/min. The isothermal chemical vapor deposition method is used for pyrolytic carbon densification. The deposition temperature is 940°C and the deposition pressure is 0.6 ~ 0.8kPa, continue to deposit 70h.

(6) The plate preforms in different deposition chambers are loaded from bottom to top in the order of L3, L2, and L1. At the same time, the individual carbon/carbon composite plates are loaded by flipping and rotating 180° along the radial direction of the confinement reactor. state, continue to deposit for 70h under the deposition process conditions of the above step (5).

(7) The prepared carbon/carbon composite material flat plate is subjected to high-temperature heat treatment at 2200° C. under an argon protective atmosphere to obtain a carbon/carbon composite material flat plate. The volume density of the obtained batches of carbon/carbon composite material plates is between 1.68 and 1.74g/cm ³ , and the carbon/carbon composite material plates in different deposition chambers are sampled, and the uniformity of the monomer volume density is less than ±0.05g/cm3. cm ³ .

The tensile strength of batch carbon/carbon composite materials is 190-210MPa, the compressive strength is 160-180MPa, and the bending strength is 180-200MPa

One piece of carbon-carbon composite material with a density of 1.72g/cm ³ was extracted, and 6 test blocks were taken from different areas for mechanical performance testing. The results are shown in Table 2:

Table 2 Mechanical properties of individual carbon-carbon composites tested in different regions

test block 3-1 3-2 3-3 3-4 3-5 3-6 density 1.71 1.75 1.73 1.75 1.70 1.74 Tensile Strength 203 205 201 207 199 203 compressive strength 171 177 172 176 171 177 Bending strength 188 194 191 195 187 193

Example 4

Uniform vapor phase densification method of carbon/carbon composite flat plate:

(1) Place the fine-woven and punctured carbon fiber preform with a size of 400×400×50mm and an apparent density of 0.74g/ ^cm3 in a high-temperature graphitization furnace, and heat treat the carbon fiber preform at 1900°C under an argon protective atmosphere , keep warm for 2 hours.

(2) Set up the confinement reactor according to the accompanying drawing 1, first place the gas distribution cap at the bottom center of the cylinder, then place the first gas distribution plate, and then use two pieces of graphite for the first group of 3 carbon fiber flat plate preforms The anti-deformation tooling is clamped and loaded on the first air distribution plate in an upright form, and any carbon fiber flat prefabricated body is guaranteed to stand upright on the blank area of the first air distribution plate; then the second air distribution plate is installed on the first air distribution plate The first set of carbon fiber flat plate prefabricated body is fixed on the outer cylinder, and the blank area in the second air distribution plate is ensured to be directly above the blank area of the first air distribution plate, and the first set of four side plates is installed at the same time , to ensure that it surrounds the air holes in the first gas distribution plate; that is, to complete the filling of the first square deposition chamber, and in the same way, complete the filling of the remaining two deposition chambers from bottom to top; from bottom to top The above is defined as L1, L2, L3. Finally, the gas collection device is placed directly above the uppermost layer deposition chamber. Complete the installation of the confinement reactor, and place it in the chemical vapor deposition furnace, make the gas distribution cap communicate with the inlet pipe in the chemical vapor phase furnace,

In this embodiment, the air distribution plates with the same layout are adopted, and any one of the air distribution plates is provided with 4 groups of air holes, the distance between each group of air holes is 60mm, and the air hole area of the air distribution plate is densely packed. Two rows of Φ12 air distribution holes, the distance between adjacent flat prefabricated bodies is 35mm.

(3) Using propylene as the carbon source gas and nitrogen as the dilution gas, the flow rate of propylene is 30L/min, and the flow rate of nitrogen is 10L/min. The isothermal chemical vapor deposition method is used for pyrolytic carbon densification, and the deposition temperature is 940°C. , the deposition pressure is 0.7-0.9kPa, and the deposition time of the first cycle is 80h.

(4) The plate preforms in different deposition chambers were loaded from bottom to top in the order of L3, L2, and L1. At the same time, the individual carbon/carbon composite plate was rotated 180° for loading, and the deposition was continued for 80 hours under the same chemical vapor deposition process conditions.

(5) Carry out surface machining on the prepared carbon/carbon composite plate, load in the order of L1, L2, and L3, and at the same time, turn the individual carbon/carbon composite plate 180° along the radial direction of the confined reactor for loading.

(6) Using propylene as the carbon source gas, nitrogen as the dilution gas, wherein the flow rate of propylene is 30L/min, and the flow rate of nitrogen gas is 10L/min. The isothermal chemical vapor deposition method is used for pyrolytic carbon densification, and the deposition temperature is 930°C. , the deposition pressure is 0.6 ~ 0.8kPa, continue to deposit for 50h.

(7) Continue to load in the order of L3, L2, and L1, and at the same time rotate the individual carbon/carbon composite material plate 180° for loading, and continue to deposit for 50 hours under the above step (6) chemical vapor deposition process conditions.

(8) Perform a high-temperature heat treatment at 2100° C. on the prepared carbon/carbon composite material plate under an argon protective atmosphere to obtain a carbon/carbon composite material plate. The volume density of the obtained batches of carbon/carbon composite material flat plates is between 1.22 and 1.28g/cm ³ , and the carbon/carbon composite material flat plates in different deposition chambers are sampled, and the uniformity of the monomer volume density is less than ±0.05g/cm3. cm ³ .

Comparative example 1

Other conditions are the same as in Example 1, only the carbon fiber flat plate prefabricated body is placed in parallel on the gas distribution plate, the volume density of the carbon/carbon composite flat plate in the obtained batch is between 1.26 ~ 1.39g/cm ³ , different deposition The chamber carbon/carbon composite material plate is sampled and checked, and the uniformity of the monomer volume density is greater than 0.14g/cm ³ .

Comparative example 2

Other conditions are the same as in Example 1, except that the carbon fiber flat plate prefabricated body is placed upright in the blank area, and the volume density of the carbon/carbon composite material flat plate in the obtained batch is between 1.30 and 1.38g/cm ³ , and the carbon in different deposition chambers /Carbon composite material plate is sampled and checked, and the uniformity of the monomer volume density is greater than 0.08g/cm ³ .

Comparative example 3

Other conditions are the same as in Example 3, except that the loading in reverse order is not carried out during the cyclic deposition process, and the bulk density of the carbon/carbon composite plate in the obtained batch is between 1.54 and 1.79 g/cm ³ , and the carbon in different deposition chambers / Sampling inspection of carbon composite material flat plate, the uniformity of monomer volume density is greater than 0.10g/cm ³ .

Comparative example 4

Other conditions are the same as in Example 4, except that the 180°C inversion is not performed during the cyclic deposition process, and the volume density of the carbon/carbon composite flat plate in the obtained batch is between 1.23 and 1.28g/cm ³ , and the carbon in different deposition chambers Sampling inspection of carbon composite flat plate, the uniformity of monomer volume density is greater than 0.16g/cm ³ .

Comparative example 5

Other conditions are the same as in Example 3, except that no side plates are set in the domain reactor, and the bulk density of the carbon/carbon composite flat plate in the obtained batch is between 1.66 and 1.72g/cm ³ , and the carbon/carbon in different deposition chambers Sampling inspection is carried out on the composite material flat plate, and the uniformity of the volume density of the monomer is greater than 0.08g/cm ³ .

The embodiments of the present invention have been described above. However, the present invention is not limited to the above-mentioned embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A method for batch-preparing flat carbon/carbon composite materials of uniform density using a confinement reactor, characterized in that: The confinement reactor includes a gas pretreatment device, a gas collection device, and a deposition device; the gas pretreatment device is located at the bottom of the confinement reactor, the gas collection device is located at the top of the confinement reactor, and the deposition device is located at the confinement reaction the middle of the device; The deposition device includes m gas distribution plates, an outer cylinder, and m-1 groups of side plates; the m≥2; There are n groups of air holes arranged at intervals on any one of the gas distribution plates, said n≥2, and the distance between any adjacent two groups of air holes is 10-100 mm; n-1 blank areas are formed between the n groups of air holes; The m gas distribution plates are arranged sequentially from bottom to top along the radial direction of the outer cylinder; The m-1 groups of side plates are arranged inside the outer cylinder, any group of side plates is vertically arranged between any two adjacent gas distribution plates, and surrounds the air holes in the gas distribution plates; The m gas distribution plates and the m-1 group of side plates divide the deposition device into m-1 deposition chambers; from the bottom to at least the first deposition chamber, the second deposition chamber, and so on to the first m-1 deposition chambers; wherein the first gas distribution plate forms the bottom of the first deposition chamber, and the m-th gas distribution plate forms the top of the m-1 deposition chamber; The method for preparing flat carbon/carbon composite materials with uniform density in batches by using the above-mentioned confined reactor comprises the following steps: 1), Confinement reactor charging Load the first group of not more than n-1 carbon fiber flat plate preforms upright on the first gas distribution plate; and ensure that any piece of carbon fiber flat prefabricated body is erected on the blank area of the first gas distribution plate; then place the second The gas distribution plate is installed on the top of the first group of carbon fiber flat prefabricated body and fixed on the outer cylinder, and ensure that the blank area in the second gas distribution plate is directly above the blank area of the first gas distribution plate, and install the second gas distribution plate at the same time 1 set of side plates, ensuring that it surrounds the air holes in the first gas distribution plate; that is, to complete the loading of the first deposition chamber, and complete the loading of the remaining m-2 deposition chambers from bottom to top in the same way material; 2), chemical vapor deposition After the loading is completed, carry out the first chemical vapor deposition on the carbon fiber flat plate prefabricated body, cool down, and unload to obtain a deposited carbon fiber flat plate preformed body; 3), repeat charging and deposition to the required density Continue to repeat the charging and chemical vapor deposition of the primary deposition preform until the volume density of the flat carbon/carbon composite material is 1.2-1.75g/cm ³ ; During the charging process, the latter charging is carried out in the reverse order of the deposition chamber of the previous charging, and during the charging process, any piece of deposited carbon fiber flat plate prefabricated The radial flip of the domain reactor is 180°. 2. A kind of method according to claim 1 using confinement reactor to prepare uniform density carbon/carbon composite material plate in batches, is characterized in that: The thickness of the carbon fiber plate prefabricated body is 25-80mm. 3. a kind of method according to claim 1 is prepared in batches with uniform density carbon/charcoal composite material flat board by using confinement reactor, it is characterized in that: The thickness of the carbon fiber flat plate prefabricated body is 6-25mm; when it is loaded vertically, it is loaded by two pieces of graphite tooling; Through holes are evenly arranged in the middle of the graphite tooling, and fastening structures are installed on the edges. The area of the graphite tooling is larger than the area of the carbon fiber flat plate prefabricated body, and after the carbon fiber flat plate prefabricated body is clamped, the carbon fiber flat flat prefabricated body is wrapped in graphite Through-hole area of tooling; The thickness of the graphite tooling is 6-15mm. 4. A kind of method according to claim 1 batch-preparing uniform density charcoal/carbon composite material flat plate by using confinement reactor, it is characterized in that: The layout of any two gas distribution plates is consistent; The m is 2 to 8; The distance between any two adjacent gas distribution plates in the vertical direction is 100-1000mm; Any group of pores on the gas distribution plate is composed of 2 to 3 rows of closely arranged pores, and the diameter of any one of the pores is 8 to 12 mm; the n is 3 to 8; The distance between any two adjacent groups of pores is 25-90mm; The distance between the vertically loaded adjacent carbon fiber flat plate preforms is 20-60mm; The arbitrary set of side plates is composed of 4 pieces of side plates, and the m pieces of gas distribution plates and m-1 sets of side plates divide the deposition device into m-1 square deposition chambers. 5. A kind of method for preparing uniform density carbon/carbon composite material plate in batches using confinement reactor according to claim 1, is characterized in that: The gas pretreatment device consists of a gas distribution cap and a cylinder. The gas distribution cap is located at the bottom center of the cylinder, and a number of gas distribution holes are uniformly arranged on the top and side walls of the cylinder to evenly distribute the gas flow into the confinement reactor. , the height of the cylinder>the height of the gas distribution cap; The gas collecting device is a cone-shaped cylinder with openings at both ends. 6. A kind of method according to claim 1 batch-preparing uniform density carbon/carbon composite material flat plate of application confinement reactor, it is characterized in that: The carbon fiber flat plate preform is selected from at least one of flat carbon felt, integral needle felt, finely punctured preform, and carbon cloth stitched preform; The apparent density of the carbon fiber plate preform is 0.15-1.0 g/cm ³ . 7. A kind of method according to claim 1 using confinement reactor to prepare uniform density carbon/carbon composite material plate in batches, it is characterized in that: The carbon fiber flat plate preform is firstly pretreated, and the pretreatment process is that the carbon fiber flat plate preform is placed in a high-temperature graphitization furnace for heat treatment at 1600-2000° C. under the protection of an inert atmosphere. 8. A kind of method according to claim 1 batch-preparing flat carbon/carbon composite materials with uniform density by using confinement reactor, it is characterized in that: The confinement reactor is placed in a vapor deposition furnace, and the gas distribution cap is connected with an air inlet pipeline in the vapor deposition furnace. 9. A kind of method according to claim 1 batch-preparing flat carbon/carbon composite materials with uniform density using confinement reactor, is characterized in that: The isothermal chemical vapor deposition method is adopted. In the chemical vapor deposition, the carbon source gas used is propylene, the diluent gas is nitrogen, and the flow ratio of the propylene to nitrogen is (1-4):1. 10. A kind of method for preparing uniform density carbon/carbon composite material plate in batches using confinement reactor according to claim 1, is characterized in that: The temperature of the chemical vapor deposition is 900-1000°C, the pressure of the chemical vapor deposition is 0.6-1.2kPa, and the time of each chemical vapor deposition is 40-120h.