CN115819101B - Method for rapidly preparing carbon/carbon composite brake disc - Google Patents
Method for rapidly preparing carbon/carbon composite brake disc Download PDFInfo
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Abstract
The invention discloses a method for rapidly preparing a carbon/carbon composite brake disc, which comprises the steps of stacking a carbon fiber preform through an internal heat source heater, effectively enabling gas to flow from the outer diameter to the inner diameter in a limiting area of M+1 deposition chambers through the design of a tool, discharging the gas to the outside of a furnace through a central pipeline, ensuring uniform concentration distribution of the gas in each limiting area, improving densification efficiency, avoiding hole sealing, better ensuring consistency of a formed carbon structure, simultaneously adopting a central heating body, enabling the carbon fiber preform to form a thermal gradient from inside to outside, and enabling the gas to be thermally decomposed and deposited to a low degree at the outer diameter of the carbon fiber preform or the carbon/carbon porous body close to an inlet nozzle in cooperation with the arrangement of a furnace wall inlet nozzle, wherein the fresh gas is diffused to the core part and the inner diameter of the carbon fiber preform or the carbon/carbon porous body, and simultaneously thermally decomposed and deposited, thereby being beneficial to improving the utilization rate of the gas and simultaneously realizing rapid densification.
Description
Technical Field
The invention belongs to the technical field of brake disc manufacturing, and particularly relates to a method for rapidly preparing a carbon/carbon composite brake disc.
Background
The carbon/carbon composite material has the characteristics of small density, high specific strength, high temperature resistance, excellent thermal shock resistance, excellent friction and wear resistance and large brake absorption energy, and becomes a good friction material. Particularly, the brake disc is applied to an airplane brake disc, and the reliability, the safety, the economy and the comfort of the airplane are obviously improved, so that the brake disc is widely applied to modern airplanes.
At present, the main stream method for preparing the carbon/carbon composite material aircraft brake disc at home and abroad is a Chemical Vapor Infiltration (CVI) technology: the carbon fiber preform is placed in a carbon source atmosphere, the carbon source gas is cracked into pyrolytic carbon under the high temperature condition, and the pyrolytic carbon is filled in the pores of the preform to densify the preform until the density is required, and meanwhile, the technological conditions of CVI are controlled to control the structure of the pyrolytic carbon. CVI technology can be divided in temperature into Isothermal Chemical Vapor Infiltration (ICVI) and Thermal Gradient Chemical Vapor Infiltration (TGCVI) technologies. The carbon/carbon composite material brake disc prepared by the ICVI technology has the advantages of stable and controllable pyrolytic carbon structure, and the brake disc with stable friction and wear performance can be finally obtained, but the densification period is long (generally more than 800 hours of densification time is needed), and the utilization rate of raw material gas is low, so that the cost of the carbon disc is high. The carbon/carbon composite material brake disc prepared by the TGCVI technology has the advantages of short densification period, high raw material gas utilization rate and low cost, but the prepared brake disc has poor pyrolytic carbon controllability, poor pyrolytic carbon structure consistency and usually needs auxiliary impregnation densification to reach the required value of density, so that the fluctuation range of the friction and wear performance of the final brake disc is large, the matching design of an aircraft brake control system is not facilitated, and the economical efficiency and the comfort of an aircraft are negatively influenced.
Therefore, how to solve the densification efficiency of the CVI technology and ensure the controllable and stable pyrolytic carbon structure obtained by the CVI is a technical problem to be solved in the preparation technology of the carbon/carbon composite material brake disc.
In order to solve the technical problems, the technical personnel research a method for quickly preparing the carbon/carbon composite material, and the patent CN101913896A densifies the carbon/carbon composite material to 1.50-1.70 g/cm by adopting the conventional CVI technology 3 Then high temperature and high pressure are carried out to obtain the density of more than or equal to 1.80g/cm 3 The method solves the problem that the carbon/carbon composite material with higher density is difficult to densify rapidly when the carbon/carbon composite material is densified again, but the cost and mass production of the carbon/carbon composite material can have short plates. The patent CN1350959A adopts thermal gradient directional flow to prepare the carbon/carbon composite material aircraft brake disc, prepares the carbon/carbon composite material with higher density in a shorter time, but the number of the brake disc to be charged is limited, and the pyrolytic carbon structure and the uniformity of the obtained brake disc are unknown.
Disclosure of Invention
The method aims at solving the problems that the existing carbon/carbon composite material brake disc CVI preparation technology is difficult to simultaneously consider the consistency of cost/period and pyrolytic carbon structure, and the product cost is high or the fluctuation range of the product performance is large. The invention aims to provide a method for rapidly preparing a carbon/carbon composite brake disc. The preparation method provided by the invention has the characteristics of short preparation period, low cost and suitability for mass production, and the prepared carbon/carbon composite material brake disc has the advantages of controlled pyrolytic carbon structure and good consistency of the pyrolytic carbon structure.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the invention relates to a preparation method of a carbon/carbon composite material brake disc, which comprises the steps of enabling the center of an annular lower end plate, a plurality of annular carbon fiber preformed bodies or carbon/carbon porous bodies and an annular upper end plate to penetrate through a heating body and loading the heating body into a chemical gas-phase furnace in a sequence from bottom to top to form a material column, wherein an annular partition plate or an annular gas limiting plate is arranged between any two adjacent carbon fiber preformed bodies or carbon/carbon porous bodies in the material column; the interval between any two annular air limiting plates is 250-500 mm, an annular lower end plate, an annular upper end plate and M groups of annular air limiting plates divide a material column into M+1 deposition chambers, M+1 groups of air inlet rings are distributed in the axial direction of the chemical vapor furnace, any group of air inlet rings are positioned on the side surface of the M+1 deposition chambers, a plurality of air inlet nozzles are uniformly distributed on any group of air inlet rings, carbon source gas and carrier gas are introduced into the furnace from the air inlet nozzles, and chemical vapor deposition densification is carried out on a carbon fiber preform or a carbon/carbon porous body, so that the carbon/carbon composite material brake disc is obtained; in the chemical vapor deposition process, the flow of the carbon source gas and the carrier gas is decreased, and the temperature of the inner side of the material column close to the heating element is controlled to decrease, and the temperature of the outer side of the material column far from the heating element is controlled to increase;
The inner diameter size of the annular gas limiting plate is consistent with that of the carbon fiber preform or the carbon/carbon porous body, the outer diameter size of the annular gas limiting plate is consistent with that of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on two end faces of the annular gas limiting plate in the circumferential direction, one end of each protruding key is flush with the inner side face of the annular gas limiting plate, the other end of each protruding key extends to be flush with the outer side face of the carbon fiber preform or the carbon/carbon porous body in the radial direction, the height of each protruding key is 1-3 mm, the number of protruding keys is 3-8, and the thickness of the annular gas limiting plate is 3-7 mm.
In the invention, the thickness of the annular gas-barrier means a thickness that does not include a protruding key.
According to the preparation method, the inner diameter is stacked by adopting a resistance heating mode, the carbon fiber preform passes through the internal heat source heater, and through the annular lower end plate and the annular upper end plate, the annular gas limiting plate can effectively enable gas to flow from the outer diameter to the inner diameter in the limiting areas of M+1 deposition chambers, then the gas is discharged to the outside of the furnace through the central pipeline, concentration distribution uniformity of the gas in each limiting area can be ensured, so that densification efficiency is improved, hole sealing is avoided, consistency of formed carbon structures can be better ensured, meanwhile, the central heating body is adopted, the carbon fiber preform forms a thermal gradient from inside to outside, the thermal decomposition and deposition degree of the gas at the outer diameter (low temperature) of the carbon fiber preform or the carbon/carbon porous body close to the gas inlet nozzle is low, the gas is diffused towards the carbon fiber preform or the carbon/carbon porous body core and the inner diameter, thermal decomposition and deposition are simultaneously carried out, and the rapid densification is realized while the gas utilization rate is improved. In the chemical deposition process, as the density of the carbon/carbon porous body increases, the porosity is reduced, and the flow of the carbon source gas and the carrier gas is controlled to decrease, so that the increase of hole sealing caused by the gas flow can be effectively avoided, and the densification in the subsequent stage is not facilitated. Along with the increase of the density of the carbon/carbon porous body, the difference of the thermal conductivity in the radial direction (the inner diameter position and the outer diameter position) is smaller and smaller, the temperature of the inner side of the material column close to the heating element is controlled to decrease, the temperature of the outer side of the material column far away from the heating element is controlled to increase, and the density uniformity of the final carbon/carbon porous body is facilitated: the temperature at the outer diameter of the early stage is low, the deposition speed is low, the density is low (the porosity is high), the temperature at the inner diameter is high, the density is high (the porosity is low), the outer diameter with high porosity is facilitated to be fast dense through the improvement of the temperature at the outer diameter of the later stage, the permeation and deposition of gas to the core are facilitated through the reduction of the temperature at the inner diameter of the later stage, the density at the inner diameter is improved, the density at the inner diameter is finally enabled to be free from density difference from the inner diameter to the outer diameter, and meanwhile, the carbon structure is controllable and consistent, and the rough layer is mainly used.
According to the invention, through the arrangement of the tooling, the carbon/carbon porous body can be in a uniform micro-gas environment, and the temperature change arrangement of the chemical vapor deposition is combined, so that the carbon/carbon composite material brake disc can realize the controllable, uniform, stable and consistent material structure and density in the mass production process.
Preferably, the density of the carbon fiber preform is 0.40-0.60 g/cm 3 。
In a preferred scheme, the carbon fiber preform is subjected to heat treatment, wherein the temperature of the heat treatment is 1600-2000 ℃, and the time of the heat treatment is 2-4 hours.
According to the invention, the carbon fiber preform is subjected to heat treatment, organic matters on the surface of the carbon fiber are volatilized through the heat treatment, the specific surface area is increased, the interface bonding strength of pyrolytic carbon and the carbon fiber is increased in the densification process of chemical vapor deposition (CVI) in the later period, and the strength of the material is increased.
In a preferred scheme, the inner diameter size of the annular lower end plate is consistent with that of the carbon fiber preform or the carbon/carbon porous body, the outer diameter size of the annular lower end plate is consistent with that of the chemical vapor furnace, a plurality of protruding keys are uniformly arranged on the circumferential direction of the upper end surface of the annular lower end plate, one end of each protruding key is flush with the inner side surface of the annular lower end plate, the other end of each protruding key extends to be flush with the outer side surface of the carbon fiber preform or the carbon/carbon porous body along the radial direction, the height of each protruding key is 1-3 mm, the number of protruding keys is 3-8, and the thickness of the annular lower end plate is 3-7 mm.
In the present invention, the thickness of the annular lower end plate does not include the height of the protruding key.
In a preferred scheme, the inner diameter and the outer diameter of the annular upper end plate are consistent with those of the carbon fiber preform or the carbon/carbon porous body, the outer diameter is consistent with the inner diameter of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on the circumferential direction of the lower end surface of the annular upper end plate, one end of each protruding key is flush with the inner side surface of the annular upper end plate, the other end of each protruding key extends to be flush with the outer side surface of the carbon fiber preform or the carbon/carbon porous body along the radial direction, the height of each protruding key is 1-3 mm, the number of protruding keys is 3-8, and the thickness of the annular upper end plate is 3-7 mm.
It can be seen that the annular upper end plate and the annular lower end plate are identical in size, one end of the protruding key is flush with the inner side surface of the annular upper end plate or the annular lower end plate, the other end of the protruding key extends to be flush with the outer side surface of the carbon fiber preform or the carbon/carbon porous body in the radial direction, namely, the length of the protruding key is identical with the span of the carbon fiber preform or the carbon/carbon porous body, only when the annular upper end plate is installed, one side of the annular upper end plate containing the protruding key is installed downwards, and one side of the annular lower end plate containing the protruding key is installed upwards.
In a preferred scheme, the inner diameter and the outer diameter of the annular partition plate are consistent with those of the carbon fiber preform or the carbon/carbon porous body, a plurality of protruding keys are uniformly arranged on the two end faces of the annular partition plate in the circumferential direction, one end of each protruding key is flush with the outer side face of the annular partition plate, the other end of each protruding key extends to be flush with the inner side face of the annular partition plate in the radial direction, the height of each protruding key is 1-3 mm, the number of protruding keys is 3-8, and the thickness of the annular partition plate is 3-7 mm.
Preferably, the materials of the annular lower end plate, the annular upper end plate, the annular partition plate and the annular air limiting plate are carbon materials, and the density is preferably more than or equal to 1.72g/cm 3 Further preferably, the density of the graphite or the carbon/carbon composite material subjected to CVI chemical vapor deposition hole sealing treatment is more than or equal to 1.74g/cm 3 Or a carbon/carbon composite material.
In the invention, the annular lower end plate, the annular upper end plate, the annular partition plate and the annular air limiting plate are effectively used as tools, so that the densification efficiency is improved, and the densification efficiency of the carbon fiber preform is improved particularly obviously. The inventor discovers that the high-density tool for hole sealing treatment is adopted, and the uniform and consistent surface of the tool is beneficial to the uniform micro-gas environment of the prefabricated body or the carbon/carbon porous body, so that the controllable, stable and consistent pyrolytic carbon is beneficial.
In a preferred scheme, the inner wall of the chemical vapor furnace is provided with a fulcrum, and the annular gas limiting plate is arranged on the fulcrum.
The inventor finds that the annular gas limiting plate is arranged on the pivot of the inner wall of the furnace, so that the function of supporting the carbon fiber preform is achieved, and adverse effects of pressure-bearing deformation, compression and the like of the lower carbon fiber preform due to the height of the furnace are avoided. Further facilitating the consistency of densification efficiency of the furnace batch products and the consistency of pyrolytic carbon structure.
In the preferred scheme, 6-10 air inlet nozzles are uniformly distributed on any group of air inlet rings.
The inventor finds that through the design that each circumferential direction is a gas ring by the furnace side gas inlet, and 6-10 gas nozzles are uniformly distributed in the circumferential direction of the gas ring, and the tooling is combined, the bearing of the bottom carbon fiber preform can be avoided, so that the carbon fiber preform or the carbon/carbon porous body is in a basically consistent stress environment, a gas flow field environment and a temperature field environment, and the limit of the height of the CVI material column is broken through.
Preferably, the gas ring of any group is arranged at 40-48% of the total height of the corresponding deposition chamber, and preferably 43-46%.
The total height in the present invention means a height from an upper end surface of the annular lower end plate or the annular gas-limiting plate to a lower end surface of an adjacent annular gas-limiting plate or annular upper end plate.
The inventor finds that the design of the gas ring position is important to uniformity of densification efficiency and consistency of pyrolytic carbon, and that too low and too high gas ring positions lead to large fluctuation range of densification efficiency and pyrolytic carbon.
In a preferred embodiment, the carbon source gas is propylene and the carrier gas is nitrogen.
In a preferred scheme, the chemical vapor deposition is divided into three sections, and in the first section of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of carbon fiber preform is 0.2-0.3 SL/Min, and the volume ratio of the carbon source gas introduced to the carrier gas introduced is 1:1.5 to 2.0; the temperature of the inner side of the material column close to the heating element is 1150-1020 ℃, the temperature of the outer side of the material column far away from the heating element is 880-970 ℃, the pressure in the furnace is controlled to be 1.0-3.0 Kpa, and the deposition time is 80-120 h;
In the second stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of carbon fiber preform is 0.15-0.25 SL/Min, and the volume ratio of the introduced carbon source gas to the introduced carrier gas is 1:1.5 to 2.0; the temperature of the inner side of the material column close to the heating element is 1110-1010 ℃, the temperature of the outer side of the material column far away from the heating element is 920-980 ℃, the pressure in the furnace is controlled to be 1.0-3.0 Kpa, and the deposition time is 80-120 h;
in the third stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of carbon fiber preform is 0.10-0.20 SL/Min, and the volume ratio of the introduced carbon source gas to the introduced carrier gas is 1:1.5 to 2.0; the temperature of the inner side of the material column close to the heating element is 1100-1000 ℃, the temperature of the outer side of the material column far away from the heating element is 930-990 ℃, the pressure in the furnace is controlled to be 1.0-3.0 Kpa, and the deposition time is 60-100 h.
In the invention, the temperature measured in the material column is the temperature of the inner side surface of the carbon fiber preform or the carbon/carbon porous body, and the temperature measured outside the material column is the temperature of the outer side surface of the carbon fiber preform or the carbon/carbon porous body.
It can be seen that in the three-stage deposition process, the temperature measured in the material column is gradually reduced, the temperature outside the material column is increased, the temperature at the outer diameter of the early stage is low, the deposition speed is low, the density is low (the porosity is high), the temperature at the inner diameter is high, the deposition speed is high, the density is high (the porosity is low), the outer diameter with high porosity is facilitated to be fast dense through the increase of the temperature at the outer diameter of the subsequent stage, the permeation and deposition of gas to the core part are facilitated through the decrease of the temperature at the inner diameter of the subsequent stage, the density at the inner diameter is increased, and finally, the density difference from the inner diameter to the outer diameter is avoided.
In the actual operation process, the temperature of the outer side of the material column is continuously increased even in the same deposition process, so that the temperature of the outer diameter is ensured by reducing the temperature of the inner diameter, for example, 1150-1020 ℃ of the temperature of the inner side of the material column which is deposited close to the heating body in the first stage, namely, the high temperature in the interval of 1150-1020 ℃ is gradually reduced to the low temperature in the interval in the process of the first stage chemical vapor deposition.
In the actual operation process, before propylene gas and nitrogen gas are introduced into the furnace, the propylene gas and the nitrogen gas are uniformly mixed by a gas mixing tank, and the uniformly mixed gas is uniformly distributed to each gas ring by a flowmeter.
Further preferably, in the first stage of chemical vapor deposition, the temperature of the inner side of the material column close to the heating element is 1110-1050 ℃, and the temperature of the outer side of the material column far from the heating element is 900-960 ℃;
during the second-stage chemical vapor deposition, the temperature of the inner side of the material column close to the heating body is
1080-1030 ℃, and the temperature of the outer side of the material column far away from the heating body is 940-970 ℃;
in the third stage of chemical vapor deposition, the temperature of the inner side of a material column close to the heating element is 1060 DEG C
The temperature of the outer side of the material column far away from the heating body is 950-980 ℃ at the temperature of 1020 ℃.
During actual operation, machining, which is a well known technique in the art, is required between the CVI stages to eliminate closed cells caused by CVI deposition, and the inventors have found in practice that the present invention results in fewer closed cells than in the prior art.
In the preferred scheme, after densification by chemical vapor deposition, the carbon/carbon composite material is subjected to heat treatment and machining, so that the carbon/carbon composite material brake disc is obtained, wherein the temperature of the heat treatment is 1800-2200 ℃ and the time is 2-4 hours.
Principle and advantages
According to the preparation method, the inner diameter is stacked by adopting a resistance heating mode, the carbon fiber preform passes through the internal heat source heater, and through the annular lower end plate and the annular upper end plate, the annular gas limiting plate can effectively enable gas to flow from the outer diameter to the inner diameter in the limiting area of M+1 deposition chambers, then the gas is discharged to the outside of the furnace through the central pipeline, concentration distribution of the gas in each limiting area can be ensured to be uniform, so that densification efficiency is improved, hole sealing is avoided, consistency of a formed carbon structure can be better ensured, meanwhile, the central heating body is adopted, the carbon fiber preform forms a thermal gradient from inside to outside, and the gas is thermally decomposed and deposited at the outer diameter (low temperature) of the carbon fiber preform or the carbon/carbon porous body close to the gas inlet nozzle in a matching manner with the arrangement of the furnace wall inlet nozzle, so that fresh gas is diffused to the carbon fiber preform or the core of the carbon/carbon porous body and the inner diameter, and simultaneously is thermally decomposed and deposited, and the gas utilization rate is improved, and rapid and compact is realized. In the chemical deposition process, as the density of the carbon/carbon porous body increases, the porosity is reduced, and the flow of the carbon source gas and the carrier gas is controlled to decrease, so that the increase of hole sealing caused by the gas flow can be effectively avoided, and the densification in the subsequent stage is not facilitated. Along with the increase of the density of the carbon/carbon porous body, the difference of the thermal conductivity in the radial direction (the inner diameter position and the outer diameter position) is smaller and smaller, the temperature of the inner side of the material column close to the heating element is controlled to decrease, the temperature of the outer side of the material column far away from the heating element is controlled to increase, and the density uniformity of the final carbon/carbon porous body is facilitated: the temperature at the outer diameter of the early stage is low, the deposition speed is low, the density is low (the porosity is high), the temperature at the inner diameter is high, the density is high (the porosity is low), the outer diameter with high porosity is facilitated to be fast dense through the improvement of the temperature at the outer diameter of the later stage, the permeation and deposition of gas to the core are facilitated through the reduction of the temperature at the inner diameter of the later stage, the density at the inner diameter is improved, the density at the inner diameter is finally enabled to be free from density difference, and meanwhile, the carbon structure is controllable and consistent, and the rough layer is mainly used.
Compared with the prior art, the invention has the following advantages:
1. the preparation method for the carbon/carbon composite material brake disc has the advantages of short period and low cost.
2. The carbon/carbon composite material brake disc prepared by the invention has good pyrolytic carbon structure consistency.
3. The charging height/number of the invention is not limited, and the invention is suitable for mass production.
The performance indexes of all materials of the carbon/carbon composite material brake disc prepared by the method meet the requirements, and the carbon/carbon composite material brake disc is used as an aircraft brake disc and has excellent quality consistency.
Drawings
FIG. 1 is a schematic diagram of a charging furnace according to the present invention.
In the figure: 1-a heating element 2-a heat insulation material 3-an annular upper end plate 4-a carbon fiber preform or a carbon/carbon porous body 5-an annular partition plate 6-an annular air limiting plate 7-an air tap 8-an annular lower end plate.
Fig. 2 is a schematic view of an annular upper end plate and an annular lower end plate, wherein the left side view is the front surface of the annular lower end plate, the back surface of the annular upper end plate, and the right side view is the front surface of the annular upper end plate, and the back surface of the annular lower end plate.
Figure 3 is a schematic view of the front and back sides of the annular partition.
FIG. 4 is a schematic view of the front and back of the annular gas-barrier.
Detailed Description
The invention is further illustrated by the following examples.
Example 1
The dimensions of the carbon fiber preform for this example were: an outer diameter of 430mm, an inner diameter of 230mm, a thickness of 25mm, a number of 60 discs, and a density of 0.5g/cm of carbon fiber preform 3 The carbon fiber preform is subjected to heat treatment at 1800 ℃ for 3 hours.
The inner diameter of the chemical deposition furnace is 500mm, and the outer diameter of the heating element is 170mm.
All tools are subjected to CVI chemical vapor deposition hole sealing treatment, and the density is 1.75g/cm 3 Carbon/carbon composite material of (a).
The inner diameter and the outer diameter of the annular upper end plate are consistent with those of the carbon fiber preform or the carbon/carbon porous body, the outer diameter of the annular upper end plate is consistent with the inner diameter of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on the lower end surface of the annular upper end plate in the circumferential direction, one end of each protruding key is flush with the inner side surface of the annular upper end plate, the other end of each protruding key extends to be flush with the outer side surface of the preform or the carbon/carbon porous body in the radial direction, the height of each protruding key is 2mm, the number of protruding keys is 6, and the thickness of the annular upper end plate is 5mm;
the inner diameter size of the annular lower end plate is consistent with that of the carbon fiber preform or the carbon/carbon porous body, the outer diameter size of the annular lower end plate is consistent with that of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on the circumferential direction of the upper end surface of the annular lower end plate, one end of each protruding key is flush with the inner side surface of the annular lower end plate, the other end of each protruding key extends to be flush with the outer side surface of the carbon fiber preform or the carbon/carbon porous body along the radial direction, the number of protruding keys is 6, and the thickness of the annular lower end plate is 5mm.
The inside and outside diameter size of annular baffle is unanimous with carbon fiber prefabrication body or carbon/porous body, and two terminal surfaces of annular baffle all circumference evenly are provided with polylith protruding key, and protruding key's one end and the lateral surface parallel and level of annular baffle, the other end along radial extension to with the medial surface parallel and level of annular baffle, protruding key's height is 2mm, and quantity is 6, the thickness of annular baffle is 5mm.
The inside diameter size of annular limit gas board is unanimous with carbon fiber prefabrication body or carbon/porous body, and external diameter size is unanimous with chemical vapor furnace internal diameter, and two terminal surfaces of annular limit gas board all circumference evenly are provided with polylith protruding key, and protruding key's one end and the medial surface parallel and level of annular limit gas board, the other end along radial extension to with carbon fiber prefabrication body or carbon/porous body lateral surface parallel and level, protruding key's height is 2mm, and quantity is 6, annular limit gas board's thickness is 5mm.
The following is a specific furnace loading and chemical vapor deposition process implementation:
firstly, the center of an annular lower end plate passes through a heating body to be loaded at the lowest part of a chemical vapor furnace, then, carbon fiber preforms are installed in the same mode, a partition plate or a gas limiting plate is installed between the two carbon fiber preforms, wherein, every 400mm (the height of 12 preforms and a tool for spacing the preforms) is provided with one gas limiting plate (the gas limiting plate is installed on the fulcrum of the inner wall of the furnace), the partition plates are installed at other positions, after all the carbon fiber preforms are loaded, the annular upper end plate is finally loaded to form a material column, 4 gas limiting plates are installed in the material column, the material column is separated into 5 deposition chambers with the annular lower end plate and the annular upper end plate, 5 groups of gas inlet rings are distributed in the axial direction of the chemical vapor furnace, any group of gas inlet rings are positioned at the side surfaces of the corresponding deposition chambers and are positioned at 45% of the total height of the deposition chambers, 8 gas inlet nozzles are uniformly distributed in the circumferential direction of any group of gas inlet rings, propylene is used as carbon source gas, nitrogen is used as carrier gas, the carbon source gas and the carrier gas is introduced into the furnace from the gas inlet nozzles, and chemical vapor deposition is carried out on the carbon fiber preforms or carbon/porous bodies.
The chemical vapor deposition is divided into three sections, and in the first section of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of carbon fiber preform is 0.25SL/Min, and the volume ratio of the introduced carbon source gas to the introduced carrier gas is 1:1.75; in the whole deposition process, the temperature of the inner side of a material column close to a heating element is 1105-1055 ℃, the temperature of the outer side of the material column far away from the heating element is 910-955 ℃, the pressure in the furnace is controlled to be 2.0Kpa, and the deposition time is 100h;
in the second stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of carbon fiber preform is 0.20SL/Min, and the volume ratio of the introduced carbon source gas to the introduced carrier gas is 1:1.75; the temperature of the inner side of the material column close to the heating element is 1070-1040 ℃, the temperature of the outer side of the material column far away from the heating element is 945-965 ℃, the pressure in the furnace is controlled to be 2.0Kpa, and the deposition time is 100h;
in the third stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of carbon fiber preform is 0.15SL/Min, and the volume ratio of the introduced carbon source gas to the introduced carrier gas is 1:1.75; in the whole deposition process, the temperature of the inner side of a material column close to a heating element is 1055-1025 ℃, the temperature of the outer side of the material column far away from the heating element is 955-975 ℃, the pressure in the furnace is controlled to be 2.0Kpa, and the deposition time is 80h.
And after densification by chemical vapor deposition, carrying out heat treatment and machining on the carbon/carbon composite material to obtain the carbon/carbon composite material brake disc, wherein the temperature of the heat treatment is 2000 ℃ and the time is 3 hours.
The average density of the carbon/carbon composite material prepared by the method is 1.821g/cm 3 The density range is 1.817 to 1.829g/cm 3 Sampling products in different deposition chambers and observing microstructure of deposited carbon, wherein the structure of the deposited carbon is a rough layer and a smooth layer, the ratio of the rough layer is 92-95%, the ratio of the smooth layer is 5-8%, visible density distribution is narrow, density is uniform, pyrolytic carbon structure distribution is narrow, and consistency is good.
Example 2
The dimensions of the carbon fiber preform for this example were: an outer diameter of 430mm, an inner diameter of 230mm, a thickness of 25mm, a number of 70 plates, and a density of 0.55g/cm of the carbon fiber preform 3 The carbon fiber preform is subjected to heat treatment at 1950 ℃ for 4 hours.
The inner diameter of the chemical deposition furnace is 500mm, and the outer diameter of the heating element is 170mm.
The used tools are all subjected to CVI chemical vapor deposition hole sealing treatment with the density of 1.75g/cm 3 Is a graphite of (a) a graphite of (b).
The inner diameter and the outer diameter of the annular upper end plate are consistent with those of the carbon fiber preform or the carbon/carbon porous body, the outer diameter of the annular upper end plate is consistent with the inner diameter of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on the lower end surface of the annular upper end plate in the circumferential direction, one end of each protruding key is flush with the inner side surface of the annular upper end plate, the other end of each protruding key extends to be flush with the outer side surface of the carbon fiber preform or the carbon/carbon porous body in the radial direction, the height of each protruding key is 3mm, the number of protruding keys is 8, and the thickness of the annular upper end plate is 7mm;
The inner diameter size of the annular lower end plate is consistent with that of the carbon fiber preform or the carbon/carbon porous body, the outer diameter size of the annular lower end plate is consistent with that of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on the circumferential direction of the upper end surface of the annular lower end plate, one end of each protruding key is flush with the inner side surface of the annular lower end plate, the other end of each protruding key extends to be flush with the outer side surface of the carbon fiber preform or the carbon/carbon porous body along the radial direction, the number of protruding keys is 8, and the thickness of the annular lower end plate is 7mm.
The inside and outside diameter size of annular baffle is unanimous with carbon fiber prefabrication body or carbon/porous body, and two terminal surfaces of annular baffle all circumference evenly are provided with polylith protruding key, and protruding key's one end and the lateral surface parallel and level of annular baffle, the other end along radial extension to with the medial surface parallel and level of annular baffle, protruding key's height is 3mm, and quantity is 8, annular baffle's thickness is 7mm.
The inner diameter size of the annular gas limiting plate is consistent with that of the carbon fiber preform or the carbon/carbon porous body, the outer diameter size of the annular gas limiting plate is consistent with that of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on two end faces of the annular gas limiting plate in the circumferential direction, one end of each protruding key is flush with the inner side face of the annular gas limiting plate, the other end of each protruding key extends to be flush with the outer side face of the carbon fiber preform or the carbon/carbon porous body in the radial direction, the height of each protruding key is 3mm, the number of protruding keys is 8, and the thickness of the annular gas limiting plate is 7mm.
The following is a specific furnace loading and chemical vapor deposition process implementation:
firstly, the center of an annular lower end plate passes through a heating body to be loaded at the lowest part of a chemical vapor furnace, then, carbon fiber preforms are installed in the same mode, a partition plate or a gas limiting plate is installed between the two carbon fiber preforms, wherein, every 480mm (the height of 14 preforms and a tool for spacing the preforms) is provided with one gas limiting plate (the gas limiting plate is installed on the fulcrum of the inner wall of the furnace), the partition plates are installed at other positions, after all the carbon fiber preforms are loaded, the annular upper end plate is finally loaded to form a material column, 4 gas limiting plates are installed in the material column, the material column is separated into 5 deposition chambers with the annular lower end plate and the annular upper end plate, 5 groups of gas inlet rings are distributed in the axial direction of the chemical vapor furnace, any group of gas inlet rings are positioned at the side surfaces of the corresponding deposition chambers and are positioned at 48% of the total height of the deposition chambers, 10 gas inlet nozzles are uniformly distributed in the circumferential direction of any group of the gas inlet rings, propylene is used as carbon source gas, nitrogen is used as carrier gas, the carbon source gas and the carrier gas is introduced into the furnace from the gas inlet nozzles, and chemical vapor deposition is carried out on the carbon fiber preforms or carbon/porous bodies.
The chemical vapor deposition is divided into three sections, and in the first section of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of preform is 0.30SL/Min, and the volume ratio of the carbon source gas to the carrier gas introduced is 1:2.0; the temperature of the inner side of the material column close to the heating element is 1150-1080 ℃, the temperature of the outer side of the material column far away from the heating element is 920-970 ℃, the pressure in the furnace is controlled to be 3.0Kpa, and the deposition time is 80h;
In the second stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of preform is 0.25SL/Min, and the volume ratio of the carbon source gas to the carrier gas introduced is 1:2.0; the temperature of the inner side of the material column close to the heating element is 1110-1060 ℃, the temperature of the outer side of the material column far away from the heating element is 950-980 ℃, the pressure in the furnace is controlled to be 3.0Kpa, and the deposition time is 100h;
in the third stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of preform is 0.20SL/Min, and the volume ratio of the carbon source gas to the carrier gas introduced is 1:2.0; the temperature of the inner side of the material column close to the heating element is 1100-1070 ℃, the temperature of the outer side of the material column far away from the heating element is 960-990 ℃, the pressure in the furnace is controlled to be 3.0Kpa, and the deposition time is 90h.
And after densification by chemical vapor deposition, carrying out heat treatment and machining on the carbon/carbon composite material to obtain the carbon/carbon composite material brake disc, wherein the temperature of the heat treatment is 2200 ℃ and the time is 2 hours.
The average density of the carbon/carbon composite material prepared by the method is 1.805g/cm 3 The density range is 1.786-1.814 g/cm 3 Sampling products in different deposition chambers and observing microstructure of deposited carbon, wherein the structure of the deposited carbon is a rough layer and a smooth layer, the ratio of the rough layer is 90-95%, the ratio of the smooth layer is 5-10%, visible density distribution is narrow, density is uniform, pyrolytic carbon structure distribution is narrow, and consistency is good.
Example 3
The dimensions of the carbon fiber preform for this example were: an outer diameter of 430mm, an inner diameter of 230mm, a thickness of 25mm, a number of 72 discs, and a density of 0.6g/cm of carbon fiber preform 3 The carbon fiber preform is subjected to heat treatment at 1650 ℃ for 2 hours.
The inner diameter of the chemical deposition furnace is 500mm, and the outer diameter of the heating element is 170mm.
All tools are subjected to CVI chemical vapor deposition hole sealing treatment, and the density is 1.76g/cm 3 Is a graphite of (a) a graphite of (b).
The inner diameter and the outer diameter of the annular upper end plate are consistent with those of the carbon fiber preform or the carbon/carbon porous body, the outer diameter of the annular upper end plate is consistent with the inner diameter of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on the lower end surface of the annular upper end plate in the circumferential direction, one end of each protruding key is flush with the inner side surface of the annular upper end plate, the other end of each protruding key extends to be flush with the outer side surface of the carbon fiber preform or the carbon/carbon porous body in the radial direction, the height of each protruding key is 1mm, the number of protruding keys is 4, and the thickness of the annular upper end plate is 3mm;
the inner diameter size of the annular lower end plate is consistent with that of the carbon fiber preform or the carbon/carbon porous body, the outer diameter size of the annular lower end plate is consistent with that of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on the circumferential direction of the upper end surface of the annular lower end plate, one end of each protruding key is flush with the inner side surface of the annular lower end plate, the other end of each protruding key extends to be flush with the outer side surface of the carbon fiber preform or the carbon/carbon porous body along the radial direction, the height of each protruding key is 1mm, the number of protruding keys is 4, and the thickness of the annular lower end plate is 3mm.
The inside and outside diameter size of annular baffle is unanimous with carbon fiber prefabrication body or carbon/porous body, and two terminal surfaces of annular baffle all circumference evenly are provided with polylith protruding key, and protruding key's one end and the lateral surface parallel and level of annular baffle, the other end along radial extension to with the medial surface parallel and level of annular baffle, protruding key's height is 1mm, and quantity is 4, the thickness of annular baffle is 3mm.
The inside diameter size of annular limit gas board is unanimous with carbon fiber prefabrication body or carbon/porous body, and external diameter size is unanimous with chemical vapor furnace internal diameter, and two terminal surfaces of annular limit gas board all circumference evenly are provided with polylith protruding key, and protruding key's one end and the medial surface parallel and level of annular limit gas board, the other end along radial extension to with carbon fiber prefabrication body or carbon/porous body lateral surface parallel and level, protruding key's height is 1mm, and quantity is 4, annular limit gas board's thickness is 3mm.
The following is a specific furnace loading and chemical vapor deposition process implementation:
firstly, the center of an annular lower end plate passes through a heating element to be loaded at the lowest part of a chemical gas-phase furnace, then, a carbon fiber preform is installed in the same way, and a partition plate or a gas limiting plate is installed between the two carbon fiber preforms, wherein every 260mm or so 9 PieceThe height of the prefabricated body and the interval tool thereof) is provided with a gas limiting plate (the gas limiting plate is arranged on a pivot of the inner wall of the furnace), other positions are provided with a baffle plate, after all the carbon fiber prefabricated bodies are loaded, the annular upper end plate is finally loaded to form a material column, 7 gas limiting plates are arranged in the material column, the annular lower end plate and the annular upper end plate divide the material column into 8 deposition chambers, 8 groups of gas inlet rings are distributed in the axial direction of the chemical gas-phase furnace, any group of gas inlet rings are positioned on the side surface of the corresponding deposition chamber and are positioned at 40% of the total height of the deposition chamber, 6 gas inlet nozzles are uniformly distributed in the circumferential direction of any group of gas inlet rings, propylene is used as carbon source gas, nitrogen is used as carrier gas, the carbon source gas and the carrier gas are introduced into the furnace through the gas inlet nozzles, and chemical gas phase deposition densification is carried out on the carbon fiber prefabricated bodies or carbon/carbon porous bodies.
The chemical vapor deposition is divided into three sections, and in the first section of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of preform is 0.2SL/Min, and the volume ratio of the carbon source gas to the carrier gas introduced is 1:1.5; the temperature of the inner side of the material column close to the heating element is 1090-1020 ℃, the temperature of the outer side of the material column far away from the heating element is 880-940 ℃, the pressure in the furnace is controlled to be 1.0Kpa, and the deposition time is 120 hours;
In the second stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of preform is 0.15SL/Min, and the volume ratio of the carbon source gas to the carrier gas introduced is 1:1.5; the temperature of the inner side of the material column close to the heating element is 1050-1010 ℃, the temperature of the outer side of the material column far away from the heating element is 920-950 ℃, the pressure in the furnace is controlled to be 1.0Kpa, and the deposition time is 120h;
in the third stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of preform is 0.10SL/Min, and the volume ratio of the carbon source gas to the carrier gas introduced is 1:1.5; the temperature of the inner side of the material column close to the heating element is 1040-1000 ℃ and the temperature of the outer side of the material column far away from the heating element is 930-960 ℃ in the whole deposition process, the pressure in the furnace is controlled to be 1.0Kpa, and the deposition time is 100h.
And after densification by chemical vapor deposition, carrying out heat treatment and machining on the carbon/carbon composite material to obtain the carbon/carbon composite material brake disc, wherein the temperature of the heat treatment is 1800 ℃ and the time is 4 hours.
The average density of the carbon/carbon composite material prepared by the method is 1.816g/cm 3 The density range is 1.797-1.826 g/cm 3 Sampling products in different deposition chambers and observing microstructure of deposited carbon, wherein the structure of the deposited carbon is a rough layer and a smooth layer, the ratio of the rough layer is 88-94%, the ratio of the smooth layer is 6-12%, visible density distribution is narrow, density is uniform, pyrolytic carbon structure distribution is narrow, and consistency is good.
Example 4
The dimensions of the carbon fiber preform for this example were: an outer diameter of 430mm, an inner diameter of 230mm, a thickness of 25mm, a number of 60 discs, and a density of 0.45g/cm of carbon fiber preform 3 The carbon fiber preform is subjected to heat treatment at 1900 ℃ for 3 hours.
The inner diameter of the chemical deposition furnace is 500mm, and the outer diameter of the heating element is 170mm.
The tool is a CVI chemical vapor deposition meterThe density of the surface deposition hole sealing treatment is 1.74g/cm 3 Is a graphite of (a) a graphite of (b).
The inner diameter and the outer diameter of the annular upper end plate are consistent with those of the carbon fiber preform or the carbon/carbon porous body, the outer diameter of the annular upper end plate is consistent with the inner diameter of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on the lower end surface of the annular upper end plate in the circumferential direction, one end of each protruding key is flush with the inner side surface of the annular upper end plate, the other end of each protruding key extends to be flush with the outer side surface of the preform or the carbon/carbon porous body in the radial direction, the height of each protruding key is 2mm, the number of protruding keys is 5, and the thickness of the annular upper end plate is 4mm;
the inner diameter size of the annular lower end plate is consistent with that of the carbon fiber preform or the carbon/carbon porous body, the outer diameter size of the annular lower end plate is consistent with that of the chemical gas-phase furnace, a plurality of protruding keys are uniformly arranged on the circumferential direction of the upper end surface of the annular lower end plate, one end of each protruding key is flush with the inner side surface of the annular lower end plate, the other end of each protruding key extends to be flush with the outer side surface of the preform or the carbon/carbon porous body along the radial direction, the number of protruding keys is 5, and the thickness of the annular lower end plate is 4mm.
The inside and outside diameter size of annular baffle is unanimous with carbon fiber prefabrication body or carbon/porous body, and two terminal surfaces of annular baffle all circumference evenly are provided with polylith protruding key, and protruding key's one end and the lateral surface parallel and level of annular baffle, the other end along radial extension to with the medial surface parallel and level of annular baffle, protruding key's height is 2mm, and quantity is 5, the thickness of annular baffle is 4mm.
The inner diameter size of the annular gas limiting plate is consistent with that of the carbon fiber preform or the carbon/carbon porous body, the outer diameter size of the annular gas limiting plate is consistent with that of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on two end faces of the annular gas limiting plate in the circumferential direction, one end of each protruding key is flush with the inner side face of the annular gas limiting plate, the other end of each protruding key extends to be flush with the outer side face of the preform or the carbon/carbon porous body in the radial direction, the protruding keys are 2mm in height and 5 in number, and the thickness of the annular gas limiting plate is 4mm.
The following is a specific furnace loading and chemical vapor deposition process implementation:
firstly, the center of an annular lower end plate passes through a heating body to be loaded at the lowest part of a chemical vapor furnace, then, carbon fiber preforms are installed in the same mode, a partition plate or a gas limiting plate is installed between the two carbon fiber preforms, wherein, every 365mm (the height of 12 preforms and a tool for spacing the preforms) is provided with one gas limiting plate (the gas limiting plate is installed on the fulcrum of the inner wall of the furnace), the partition plates are installed at other positions, after all the carbon fiber preforms are loaded, the annular upper end plate is finally loaded to form a material column, 4 gas limiting plates are installed in the material column, the material column is separated into 5 deposition chambers with the annular lower end plate and the annular upper end plate, 5 groups of gas inlet rings are distributed in the axial direction of the chemical vapor furnace, any group of gas inlet rings are positioned at the side surfaces of the corresponding deposition chambers and are positioned at 44% of the total height of the deposition chambers, 9 gas inlet nozzles are uniformly distributed in the circumferential direction of any group of gas inlet rings, propylene is used as carbon source gas, nitrogen is used as carrier gas, the carbon source gas and the carrier gas is introduced into the furnace from the gas inlet nozzles, and chemical vapor deposition is carried out on the carbon fiber preforms or carbon/porous bodies.
The chemical vapor deposition is divided into three sections, and in the first section of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of preform is 0.22SL/Min, and the volume ratio of the carbon source gas to the carrier gas introduced is 1:1.6; the temperature of the inner side of the material column close to the heating element is 1100-1040 ℃, the temperature of the outer side of the material column far away from the heating element is 910-960 ℃, the pressure in the furnace is controlled to be 1.5Kpa, and the deposition time is 120h;
in the second stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of preform is 0.22SL/Min, and the volume ratio of the carbon source gas to the carrier gas introduced is 1:1.9; the temperature of the inner side of the material column close to the heating element is 1070-1030 ℃, the temperature of the outer side of the material column far away from the heating element is 930-970 ℃, the pressure in the furnace is controlled to be 2.5Kpa, and the deposition time is 90h;
in the third stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of preform is 0.14SL/Min, and the volume ratio of the carbon source gas to the carrier gas introduced is 1:1.7; in the whole deposition process, the temperature of the inner side of a material column close to a heating body is 1060-1035 ℃, the temperature of the outer side of the material column far away from the heating body is 945-980 ℃, the pressure in the furnace is controlled to be 2.1Kpa, and the deposition time is 90 hours.
And after densification by chemical vapor deposition, carrying out heat treatment and machining on the carbon/carbon composite material to obtain the carbon/carbon composite material brake disc, wherein the temperature of the heat treatment is 2150 ℃ and the time is 3 hours.
The average density of the carbon/carbon composite material prepared by the method is 1.812g/cm 3 The density range is 1.791-1.825 g/cm 3 Sampling products in different deposition chambers and observing microstructure of deposited carbon, wherein the structure of the deposited carbon is a rough layer and a smooth layer, the ratio of the rough layer is 89-94%, the ratio of the smooth layer is 6-11%, visible density distribution is narrow, density is uniform, pyrolytic carbon structure distribution is narrow, and consistency is good.
Comparative example 1
The other conditions were the same as in example 1, except that: the annular partition plate is used to replace the gas limiting plate. The average density of the carbon/carbon composite material prepared by the method is 1.782g/cm 3 The density range is 1.751-1.831 g/cm 3 Sampling products in different deposition chambers and observing microstructure of deposited carbon, wherein the microstructure of the deposited carbon is a rough layer and a smooth layer, the rough layer accounts for 50-85%, and the smooth layer accounts for 15-50%.
Comparative example 2
The other conditions were the same as in example 1, except that: the density of the tool is 1.50-1.65 g/cm 3 And is not subjected to CVI chemical vapor surface hole sealing treatment.
The average density of the carbon/carbon composite material prepared by the method is 1.794g/cm 3 The density range is 1.772-1.813 g/cm 3 The products of different deposition chambers are sampled and observed to obtain the microstructure of the deposited carbon, wherein the microstructure of the deposited carbon is a rough layer and a smooth layer, the rough layer accounts for 70-82%, and the smooth layer accounts for 18-30%.
Comparative example 3
The other conditions were the same as in example 1, except that: a gas limiting plate is arranged every 600mm, and the average density of the carbon/carbon composite material prepared by the method is 1.799g/cm 3 The density range is 1.782-1.816 g/cm 3 Sampling the products of different deposition chambers and observing the microstructure of the deposited carbon, depositingThe carbon structure is a rough layer and a smooth layer, wherein the rough layer accounts for 78-90%, and the smooth layer accounts for 10-22%.
Comparative example 4
The other conditions were the same as in example 1, except that: the gas ring height is located at 60% of the total height of the deposition chamber.
The average density of the carbon/carbon composite material prepared by the method is 1.804g/cm 3 The density range is 1.773-1.821 g/cm 3 The products of different deposition chambers are sampled and observed to obtain the microstructure of the deposited carbon, wherein the microstructure of the deposited carbon is a rough layer and a smooth layer, the rough layer accounts for 79-88 percent, and the smooth layer accounts for 12-21 percent.
Comparative example 5
The other conditions were the same as in example 1, except that: in the whole deposition process of the first-stage chemical vapor deposition, the temperature of the inner side of the material column close to the heating element is 1210-1155 ℃, and the temperature of the outer side of the material column far from the heating element is 975-1050 ℃.
The average density of the carbon/carbon composite material prepared by the method is 1.654g/cm 3 The density range is 1.513-1.731 g/cm 3 . Sampling products in different deposition chambers and observing microstructure of deposited carbon, wherein the microstructure of the deposited carbon comprises a rough layer, a smooth layer and a transition layer, the rough layer accounts for 30-55%, the smooth layer accounts for 20-40%, and the transition layer accounts for 5-50%.
Comparative example 6
The other conditions were the same as in example 1, except that: in the first stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of preform is 0.35SL/Min, and the volume ratio of the carbon source gas to the carrier gas introduced is 1:1.3;
the average density of the carbon/carbon composite material prepared by the method is 1.705g/cm 3 The density range is 1.684-1.730 g/cm 3 . The products of different deposition chambers are sampled and observed to obtain the microstructure of the deposited carbon, wherein the microstructure of the deposited carbon is a rough layer and a smooth layer, the rough layer accounts for 79-88 percent, and the smooth layer accounts for 12-21 percent.
Comparative example 7
The other conditions were the same as in example 1, except that: 1) The number of the charging preforms is 30 discs, and 2) the annular lower end plate, the annular upper end plate, the annular partition plate and the air limiting plate are not adopted, but conventional charging tools (supporting plates, gaskets and cover plates) are adopted for charging.
The average density of the carbon/carbon composite material prepared by the method is 1.785g/cm 3 The density range is 1.764-1.807 g/cm 3 . Sampling products in different deposition chambers and observing microstructure of deposited carbon, wherein the structure of the deposited carbon is a rough layer and a smooth layer, the rough layer accounts for 30-85%, the smooth layer accounts for 15-70%, and the structure is uneven.
Comparative example 8
The other conditions were the same as in example 1, except that: instead of the annular lower end plate, the annular upper end plate, the annular partition plate and the annular air limiting plate, the conventional furnace charging tool (supporting plate, gasket and cover plate) is adopted for charging; and the thickness of the gasket is 2mm, the thickness of the supporting plate and the cover plate is 5mm, and the total height of the material column is about 1630mm.
The average density of the carbon/carbon composite material prepared by the method is 1.767g/cm 3 The density range is 1.725-1.817 g/cm 3 . And even if 50% of the product is continuously deposited and densified, the density cannot be more than or equal to 1.78g/cm 3 Sampling products in different deposition chambers and observing microstructure of deposited carbon, wherein the microstructure of the deposited carbon is a rough layer and a smooth layer, the rough layer accounts for 20-82%, the smooth layer accounts for 18-80%, and the structure is uneven.
The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, alterations and equivalent structural changes made to the above embodiments according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.
Claims (5)
1. A preparation method of a carbon/carbon composite brake disc is characterized by comprising the following steps: the method comprises the steps of enabling the centers of an annular lower end plate, a plurality of annular carbon fiber preformed bodies or carbon/carbon porous bodies and an annular upper end plate to penetrate through a heating body and to be loaded in a chemical gas-phase furnace in sequence from bottom to top to form a material column, wherein an annular partition plate or an annular gas limiting plate is arranged between any two adjacent carbon fiber preformed bodies or carbon/carbon porous bodies in the material column; the interval between any two annular gas limiting plates is 250-500 mm, the annular lower end plate, the annular upper end plate and the M groups of annular gas limiting plates divide a material column into M+1 deposition chambers, M+1 groups of gas inlet rings are distributed in the axial direction of the chemical vapor furnace, any group of gas inlet rings are positioned on the side surface of the M+1 deposition chambers, a plurality of gas inlet nozzles are uniformly distributed on any group of gas inlet rings, carbon source gas and carrier gas are introduced into the furnace from the gas inlet nozzles, and chemical vapor deposition densification is carried out on a carbon fiber preform or a carbon/carbon porous body, so that the carbon/carbon composite material brake disc is obtained; in the chemical vapor deposition process, the flow of the carbon source gas and the carrier gas is decreased, and the temperature of the inner side of the material column close to the heating element is controlled to decrease, and the temperature of the outer side of the material column far from the heating element is controlled to increase;
The inner diameter size of the annular gas limiting plate is consistent with that of the carbon fiber preform or the carbon/carbon porous body, the outer diameter size of the annular gas limiting plate is consistent with that of the chemical gas phase furnace, a plurality of protruding keys are uniformly arranged on two end faces of the annular gas limiting plate in the circumferential direction, one end of each protruding key is flush with the inner side face of the annular gas limiting plate, the other end of each protruding key extends to be flush with the outer side face of the preform or the carbon/carbon porous body in the radial direction, the height of each protruding key is 1-3 mm, the number of protruding keys is 3-8, and the thickness of each annular gas limiting plate is 3-7 mm;
the inner diameter of the annular lower end plate is consistent with the inner diameter of the carbon fiber preform or the carbon/carbon porous body, the outer diameter of the annular lower end plate is consistent with the inner diameter of the chemical vapor furnace, a plurality of protruding keys are uniformly arranged on the upper end surface of the annular lower end plate in the circumferential direction, one end of each protruding key is parallel and level with the inner side surface of the annular lower end plate, the other end of each protruding key extends to be parallel and level with the outer side surface of the preform or the carbon/carbon porous body along the radial direction, the height of each protruding key is 1-3 mm, the number of protruding keys is 3-8, and the thickness of the annular lower end plate is 3-7 mm;
the inner diameter and the outer diameter of the annular upper end plate are consistent with those of the carbon fiber preform or the carbon/carbon porous body, the outer diameter of the annular upper end plate is consistent with the inner diameter of the chemical vapor furnace, a plurality of protruding keys are uniformly arranged on the lower end surface of the annular upper end plate in the circumferential direction, one end of each protruding key is flush with the inner side surface of the annular upper end plate, the other end of each protruding key extends to be flush with the outer side surface of the preform or the carbon/carbon porous body in the radial direction, the height of each protruding key is 1-3 mm, the number of protruding keys is 3-8, and the thickness of the annular upper end plate is 3-7 mm;
The inner diameter and the outer diameter of the annular partition plate are consistent with those of the carbon fiber preform or the carbon/carbon porous body, a plurality of protruding keys are uniformly arranged on two end faces of the annular partition plate in the circumferential direction, one end of each protruding key is flush with the outer side face of the annular partition plate, the other end of each protruding key extends to be flush with the inner side face of the annular partition plate in the radial direction, the height of each protruding key is 1-3 mm, the number of protruding keys is 3-8, and the thickness of each annular partition plate is 3-7 mm;
the annular lower end plate, the annular upper end plate, the annular partition plate and the annular gas limiting plate are made of materials subjected to CVI chemical vapor deposition hole sealing treatment, and the density is more than or equal to 1.74g/cm 3 Is a graphite or carbon/carbon composite material;
the inner wall of the chemical gas-phase furnace is provided with a fulcrum, and the annular gas limiting plate is arranged on the fulcrum;
6-10 air inlet nozzles are uniformly distributed on the air inlet ring;
the air inlet ring is arranged at 40-48% of the total height of the corresponding deposition chamber;
the chemical vapor deposition is divided into three sections, and during the first section chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of carbon fiber preform is 0.2-0.3SL/Min, and the volume ratio of the carbon source gas introduced to carrier gas introduced is 1: 1.5-2.0; the temperature of the inner side of the material column close to the heating element is 1150-1020 ℃, the temperature of the outer side of the material column far away from the heating element is 880-970 ℃, the pressure in the furnace is controlled to be 1.0-3.0 kPa, and the deposition time is 80-120 hours;
In the second stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of carbon fiber preform is 0.15-0.25 SL/Min, and the volume ratio of the introduced carbon source gas to the introduced carrier gas is 1: 1.5-2.0; the temperature of the inner side of the material column close to the heating element is 1110-1010 ℃, the temperature of the outer side of the material column far away from the heating element is 920-980 ℃, the pressure in the furnace is controlled to be 1.0-3.0 kPa, and the deposition time is 80-120 hours;
in the third stage of chemical vapor deposition, the flow rate of carbon source gas introduced into each kilogram of carbon fiber preform is 0.10-0.20 SL/Min, and the volume ratio of the introduced carbon source gas to the introduced carrier gas is 1: 1.5-2.0; the temperature of the inner side of the material column close to the heating element is 1100-1000 ℃, the temperature of the outer side of the material column far away from the heating element is 930-990 ℃, the pressure in the furnace is controlled to be 1.0-3.0 kPa, and the deposition time is 60-100 h.
2. The method for manufacturing the carbon/carbon composite brake disc according to claim 1, wherein the method comprises the following steps: the density of the carbon fiber preform is 0.40-0.60 g/cm 3 ；
The carbon fiber preform is subjected to heat treatment, wherein the temperature of the heat treatment is 1600-2000 ℃, and the time of the heat treatment is 2-4 hours.
3. The method for manufacturing the carbon/carbon composite brake disc according to claim 1, wherein the method comprises the following steps: the carbon source gas is propylene, and the carrier gas is nitrogen.
4. The method for manufacturing the carbon/carbon composite brake disc according to claim 1, wherein the method comprises the following steps: during the first-stage chemical vapor deposition, the temperature of the inner side of a material column close to a heating element is 1110-1050 ℃, and the temperature of the outer side of the material column far from the heating element is 900-960 ℃;
during the second-stage chemical vapor deposition, the temperature of the inner side of a material column close to the heating element is 1080-1030 ℃, and the temperature of the outer side of the material column far from the heating element is 940-970 ℃;
and in the third-stage chemical vapor deposition, the temperature of the inner side of the material column close to the heating element is 1060-1020 ℃, and the temperature of the outer side of the material column far from the heating element is 950-980 ℃.
5. The method for manufacturing the carbon/carbon composite brake disc according to claim 1, wherein the method comprises the following steps: and after densification by chemical vapor deposition, carrying out heat treatment and machining on the carbon/carbon composite material to obtain the carbon/carbon composite material brake disc, wherein the temperature of the heat treatment is 1800-2200 ℃ and the time is 2-4 hours.
Priority Applications (1)
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