Tool for chemical vapor infiltration process and preparation method and application of carbon-carbon composite material

Abstract

The invention belongs to the technical field of preparation of carbon-carbon composite materials, and particularly relates to a tool for a chemical vapor infiltration process and a preparation method and application of a carbon-carbon composite material. The tool for the chemical vapor infiltration process comprises a to-be-treated prefabricated body group, wherein a through hole penetrating through the to-be-treated prefabricated body group is formed in the center of the to-be-treated prefabricated body group; the to-be-treated prefabricated body group comprises prefabricated body layers and flow guide layers which are alternately stacked; the prefabricated body layer comprises a prefabricated body to be treated; the flow guide layer comprises a plurality of flow guide gaskets which are uniformly arranged between the adjacent prefabricated body layers, and an airflow channel is formed between the adjacent flow guide gaskets; the carbon source gas release device comprises a gas outlet end, and the gas outlet end is located at the bottom of the through hole of the to-be-treated preform group; and the gas path spoiler covers the top of the to-be-treated prefabricated body group. When the tool is used for preparing the carbon-carbon composite material, the densification efficiency of the material can be improved, the preparation period is shortened, meanwhile, the utilization rate of a carbon source can be increased, and defects in the carbon-carbon composite material are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon-carbon composite material preparation, and specifically relates to a tooling for a chemical vapor infiltration process and a carbon-carbon composite material preparation method and application. Background Art

[0002] Carbon-carbon composite materials have the advantages of low density, high strength, good friction performance, dimensional stability, etc. They have been widely used in the fields of medical, aerospace, automotive parts, etc., and have broad development prospects. The existing methods for preparing carbon-carbon composite materials include chemical vapor infiltration (CVI), precursor impregnation pyrolysis (PIP), chemical liquid vapor deposition (CLVI), etc. Isothermal chemical vapor infiltration is mainly used in industrial production. However, the preparation cycle of isothermal chemical vapor infiltration is very long, and it may take thousands of hours depending on the product. For example, when preparing carbon-carbon brake discs, they are densified to 1.75g / cm 3 It takes 1800 to 2100 hours. That is, when the existing isothermal chemical vapor infiltration process is used to prepare carbon-carbon composite materials, the densification efficiency is low, the carbon source utilization rate is low, the preparation cycle is long, and the cost is high, which greatly limits the expansion of the application market of carbon-carbon composite materials. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defects of low densification efficiency, low carbon source utilization, long preparation cycle and high cost when using chemical vapor infiltration process to prepare carbon-carbon composite materials in the prior art, thereby providing tooling for chemical vapor infiltration process and carbon-carbon composite material preparation method and application.

[0004] To this end, the present invention provides the following technical solutions:

[0005] The present invention provides a tooling for a chemical vapor infiltration process, comprising: a preform group to be processed, wherein a through hole penetrating the preform group to be processed is provided at a central position of the preform group to be processed; the preform group to be processed comprises alternately stacked preform layers and guide layers; the preform layers comprise preforms to be processed; the guide layers comprise a plurality of guide gaskets uniformly arranged between adjacent preform layers, and an air flow channel is formed between adjacent guide gaskets; a carbon source gas release device, wherein the carbon source gas release device comprises an air outlet end, and the air outlet end is located at the bottom of the through hole of the preform group to be processed; and an air path baffle, wherein the air path baffle covers the top of the preform group to be processed.

[0006] The chemical vapor infiltration tooling provided by the present invention has no requirements on the specifications of the preform. Typically, but not limitedly, the preform can be a thick piece, a sheet piece, a tubular piece, an annular piece, etc., and the outermost circle shape of the cross-section of the preform can be circular, triangular, square, polygonal, etc.

[0007] Optionally, the guide gasket is in the shape of at least one of an arc and a straight line; two ends of the guide gasket are respectively located at the inner edge of the preform layer and the outer edge of the preform layer; optionally, the guide gasket is in the shape of an arc.

[0008] Optionally, each guide layer includes 5 to 8 guide pads evenly laid.

[0009] Optionally, the number of guide pads laid in each guide layer is the same, and the guide pads laid in each guide layer overlap in the vertical direction.

[0010] Optionally, when the guide gasket is in an arc shape, at the intersection of the guide gasket and the inner edge of the preform layer, the angle between the tangent of the guide gasket and the radial position of the inner edge of the preform is 90° to 140°.

[0011] Optionally, the guide gasket has a thickness of 2 to 6 mm and a width of 10 to 20 mm; according to currently commonly used specifications of carbon-carbon composite materials, when using an arc-shaped guide gasket, the radius corresponding to the inner arc of the guide gasket is 300 to 500 mm; typically and non-limitingly, the guide gasket can be prepared separately or cut from a finished ring.

[0012] Optionally, the gas outlet end of the carbon source gas release device comprises a hollow cavity, and the side wall of the cavity is provided with holes; the gas outlet end is connected to the gas inlet end through a spiral gas inlet pipe.

[0013] Optionally, the holes include first holes and second holes that are staggered; the diameter ratio of the first holes to the second holes is 1.5 to 2.5:1; optionally, the diameter range of the first holes is 4 to 7 mm; optionally, the number ratio of the first holes to the second holes is 1:0.8 to 1.2; further optionally, the diameter ratio of the first holes to the second holes is 2:1.

[0014] Optionally, the wall thickness of the cavity is 2 to 5 mm.

[0015] Optionally, the total length of the air intake duct is ≥1200 mm.

[0016] Optionally, it also includes an air inlet, which is located at the bottom of the tooling and is connected to the air inlet end of the carbon source gas release device.

[0017] Optionally, it also includes a preform placement table located at the bottom of the tooling, the preform placement table having a through hole at the center position, and the through hole is used to place the carbon source gas release device; optionally, the cavity of the carbon source gas release device is higher than the upper surface of the preform placement table; further optionally, the upper surface of the carbon source gas release device is not higher than the upper surface of the second layer of preforms from the bottom up.

[0018] Optionally, the bottom of the preform group to be processed is a guide layer.

[0019] Optionally, a furnace shell is also included; optionally, an air outlet is provided on the top of the furnace shell.

[0020] Optionally, the guide gasket is a carbon guide gasket; optionally, the material of the guide gasket is graphite.

[0021] The present invention provides a method for preparing a carbon-carbon composite material, comprising the following steps:

[0022] Step 1) alternately stacking preform layers and guide layers in a furnace body to form a preform group to be processed; the preform layers include preforms to be processed; the guide layers include a plurality of guide pads evenly arranged between adjacent preform layers, and air flow channels are formed between adjacent guide pads;

[0023] Step 2) using a gas path baffle to cover the top of the preform group to be processed;

[0024] Step 3) Introducing carbon source gas into the bottom of the preform group to be processed to perform densification treatment on the preform group to be processed so that the density of the preforms to be processed reaches the target density.

[0025] Optionally, the densification treatment method includes: using natural gas and propane with a gas flow ratio of 3 to 10:1 as carbon source gas, the preparation temperature is 900 to 1100° C., and the furnace chamber pressure during the preparation process is 0 to 10 kPa.

[0026] Optionally, the target density is > 1.7 g / cm 3 The densification treatment includes: in the first stage, natural gas and propane with a gas flow ratio of 4 to 5:1 are used as carbon source gases, the total gas flow range is 36 to 60 L / min, the carbon source utilization rate is 30% to 40%, and the preform is densified to 1.1 to 1.3 g / cm 3 The total gas flow rate is mainly related to the capacity of the equipment, i.e., the furnace volume, the working efficiency of the vacuum pump, etc., and can be adaptively adjusted according to the actual situation. In the second stage, natural gas and propane with a gas flow ratio of 3 to 4:1 are used as carbon source gases, the total gas flow range is 18 to 36 L / min, the carbon source utilization rate is 30% to 40%, and the preform is densified to 1.6 to 1.7 g / cm 3 ; Considering that the preform has a higher density in this stage, under the conditions basically the same as those in the first stage, the amount of carbon adsorbed by the preform is reduced; in the third stage, natural gas and propane with a gas flow ratio of 5 to 10:1 are used as carbon source gases, the total gas flow range is 10 to 18 L / min, and the carbon source utilization rate is 15% to 25%, and the preform is densified to the target density.

[0027] Optionally, the target density of the carbon-carbon composite material is 1.3 to 1.7 g / cm 3 And does not include 1.3g / cm 3 The densification treatment includes: in the first stage, natural gas and propane with a gas flow ratio of 4 to 5:1 are used as carbon source gases, the total gas flow range is 36 to 60 L / min, and the carbon source utilization rate is 30% to 40%, and the preform is densified to 1.1 to 1.3 g / cm 3 In the second stage, natural gas and propane with a gas flow ratio of 3 to 4:1 are used as carbon source gases, the total gas flow range is 18 to 36 L / min, and the carbon source utilization rate is 30% to 40%, and the preform is densified to the target density.

[0028] Optionally, the target density of the carbon-carbon composite material is ≤1.3 g / cm 3 , using natural gas and propane with a gas flow ratio of 4 to 5:1 as the carbon source gas, the total gas flow range is 36 to 60 L / min, and the carbon source utilization rate is 30% to 45%, and the preform is densified to the target density.

[0029] Optionally, the method further includes the step of densifying the carbon-carbon composite material obtained after the third stage which does not reach the target density in the fourth stage; optionally, in the fourth stage, natural gas and propane with a gas flow ratio of 10 to 20:1 are used as the carbon source gas, the total gas flow range is 5 to 10 L / min, and the carbon source utilization rate is 5% to 15%.

[0030] Optionally, the density of the preform is 0.38-0.6 g / cm 3 .

[0031] Optionally, the carbon-carbon composite material is prepared using the above-mentioned chemical vapor infiltration process tooling; optionally, when assembling the tooling, the carbon source gas release device is placed first, and then the preform is placed.

[0032] The present invention also provides a carbon-carbon composite material, which is prepared by the above preparation method or prepared by using the above chemical vapor infiltration process tooling.

[0033] The present invention also provides an application of the carbon-carbon composite material in a brake device.

[0034] The beneficial effects of the present invention are:

[0035] The tooling for chemical vapor infiltration process provided by the present invention comprises: a preform group to be processed, wherein a through hole penetrating the preform group to be processed is provided at the center position of the preform group to be processed; the preform group to be processed comprises alternately stacked preform layers and guide layers; the preform layer comprises the preform to be processed; the guide layer comprises a plurality of guide gaskets uniformly arranged between adjacent preform layers, and an air flow channel is formed between adjacent guide gaskets; a carbon source gas release device, wherein the carbon source gas release device comprises an air outlet end, wherein the air outlet end is located at the bottom of the through hole of the preform group to be processed; and an air path baffle, wherein the air path baffle covers the top of the preform group to be processed. The use of the tooling to prepare carbon-carbon composite materials can effectively improve the material densification efficiency, shorten the preparation cycle of carbon-carbon composite materials, and at the same time improve the utilization rate of the carbon source and reduce the generation of defects in the carbon-carbon composite materials. The tooling provided by the present invention uses specific assembly parts, especially the design of the guide plate and the carbon source gas release device, which can increase the contact area and contact time between the carbon source gas and the preform, ensure the uniform distribution of the bottom gas flow and the gas flow in the whole preform during the deposition process of the preform, and avoid frequent replacement of the preform position during the deposition stage. The gas path baffle covers the top of the preform group to be processed, which helps to extend the residence time of the carbon source gas in the preform.

[0036] In the tooling for chemical vapor infiltration process provided by the present invention, the number of guide gaskets laid in each guide layer is the same, and the guide gaskets laid in each guide layer overlap in the vertical direction, which can effectively prevent the preform from being deformed during the preparation process.

[0037] The present invention provides a tooling for chemical vapor infiltration process, wherein the outlet end of the carbon source gas release device includes a hollow cavity, and the side wall of the cavity is provided with holes; the outlet end is connected to the inlet end through a spiral inlet pipe. The carbon source gas release device can improve the flow state of the gas inside the furnace chamber and avoid the decrease in the deposition efficiency of some preforms, wherein the spiral inlet pipe can increase the time for the carbon source gas to reach the inside of the tooling and preheat it, and the hollow cavity with holes on the side wall can effectively disperse the carbon source gas and make it diffuse evenly in the tooling.

[0038] The preparation method of the carbon-carbon composite material provided by the present invention comprises the following steps: step 1) alternately stacking a preform layer and a guide layer in a furnace body to form a preform group to be processed; the preform layer comprises a preform to be processed; the guide layer comprises a plurality of guide pads evenly arranged between adjacent preform layers, and an air flow channel is formed between adjacent guide pads; step 2) using an air path baffle to cover the top of the preform group to be processed; step 3) introducing a carbon source gas into the bottom of the preform group to be processed, and performing a densification treatment on the preform group to be processed, so that the density of the preform to be processed reaches a target density. By specifically assembling the preform group to be processed, the densification speed during the preparation process can be improved.

[0039] The preparation method of the carbon-carbon composite material provided by the present invention uses natural gas and propane with a gas flow ratio of 3 to 10:1 as carbon source gas, the preparation temperature is 900 to 1100°C, and the furnace chamber pressure during the preparation process is 0 to 10 kPa; the target density is greater than 1.7 g / cm 3 The densification treatment includes: in the first stage, natural gas and propane with a gas flow ratio of 4 to 5:1 are used as carbon source gases, the total gas flow range is 36 to 60 L / min, the carbon source utilization rate is 30% to 40%, and the preform is densified to 1.1 to 1.3 g / cm 3 In the second stage, natural gas and propane with a gas flow ratio of 3 to 4:1 are used as carbon source gases, the total gas flow range is 18 to 36 L / min, the carbon source utilization rate is 30% to 40%, and the preform is densified to 1.6 to 1.7 g / cm 3 ; In the third stage, natural gas and propane with a gas flow ratio of 5 to 10:1 are used as carbon source gases, the total gas flow range is 10 to 18 L / min, and the carbon source utilization rate is 15% to 25%, and the preform is densified to the target density. By controlling the carbon source gas, the densification speed in the preparation process is improved; and by controlling the carbon source utilization rate at each stage, the open porosity of the carbon-carbon composite material is guaranteed. When the high-temperature carbon source gas flows through the surface of the preform, a part of it is directly cracked on the surface, and the pyrolytic carbon is attached to the surface carbon fiber, and the other part enters the interior of the preform through the holes on the surface of the preform for cracking and deposition; when the preform has a certain density, the permeability of the carbon source gas decreases. At this time, reducing the carbon content in the gas flow can slow down the carbon deposition on the surface, thereby ensuring the open porosity of the carbon-carbon composite material.

[0040] The method for preparing the carbon-carbon composite material provided by the present invention uses the above-mentioned chemical vapor infiltration process tooling for preparation. The combination of the two increases the residence time of the carbon source gas inside the preform, greatly improving the densification rate of the carbon-carbon composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 It is a schematic diagram of the tooling used in the chemical vapor infiltration process of the present invention;

[0043] Figure 2 is a schematic diagram of the placement of guide vanes in the present invention;

[0044] Figure 3 is a schematic diagram of a carbon source gas release device in the present invention;

[0045] Description of reference numerals:

[0046] 1-air inlet; 2-carbon source gas release device; 201-air inlet pipe; 202-cavity; 3-preform layer; 301-inner edge of preform layer; 302-outer edge of preform layer; 4-guide layer; 401-guide gasket; 5-gas path baffle; 6-furnace shell; 7-air outlet. DETAILED DESCRIPTION

[0047] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0049] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] Experimental drugs:

[0051] Preform: φ470mm×φ240mm×30mm, 0.45±0.05g / cm 3 , Jiangyou Tianqi Guangfeng New Materials Technology Co., Ltd.

[0052] Example 1

[0053] Reference below Figure 1 , 23. Describe the tooling for chemical vapor infiltration process according to an embodiment of the present invention.

[0054] The chemical vapor infiltration process tooling provided in the embodiment of the present invention comprises: a preform group to be processed, wherein a through hole penetrating the preform group to be processed is provided at the center of the preform group to be processed; the preform group to be processed comprises alternately stacked preform layers 3 and guide layers 4; the preform layer 3 comprises preforms to be processed; the guide layer 4 comprises a plurality of guide gaskets 401 uniformly arranged between adjacent preform layers 3, and an air flow channel is formed between adjacent guide gaskets 401;

[0055] A carbon source gas releasing device 2, wherein the carbon source gas releasing device 2 comprises a gas outlet end, and the gas outlet end is located at the bottom of the through hole of the preform group to be processed;

[0056] A gas path baffle plate 5, wherein the gas path baffle plate 5 covers the top of the preform group to be processed.

[0057] In some embodiments, the guide gasket 401 is at least one of an arc shape and a straight line shape; two ends of the guide gasket 401 are respectively located at the inner edge 301 of the preform layer and the outer edge 302 of the preform layer.

[0058] In some embodiments, each guide layer 4 includes 5 to 8 uniformly laid guide pads 401 .

[0059] In some embodiments, the number of guide pads 401 laid in each guide layer 4 is the same, and the guide pads 401 laid in each guide layer 4 overlap in the vertical direction.

[0060] In some embodiments, when the guide gasket 401 is in an arc shape, at the intersection of the guide gasket 401 and the inner edge 301 of the preform layer, the angle between the tangent of the guide gasket 401 and the radial direction of the inner edge 301 of the preform layer is 90° to 140°. Figure 2 ∠α in .

[0061] In some embodiments, the guide gasket 401 has a thickness of 2 to 6 mm and a width of 10 to 20 mm.

[0062] In some embodiments, the gas outlet of the carbon source gas release device 2 includes a hollow cavity 202 , and the side wall of the cavity 202 is provided with holes; the gas outlet is connected to the gas inlet via a spiral gas inlet pipe 201 .

[0063] In some embodiments, the holes include first holes and second holes that are staggered; the diameter ratio of the first holes to the second holes is 1.5-2.5:1.

[0064] In some embodiments, the diameter of the first hole ranges from 4 to 7 mm.

[0065] In some embodiments, the ratio of the number of the first holes to the number of the second holes is 1:0.8-1.2.

[0066] In some embodiments, the diameter ratio of the first hole to the second hole is 2:1.

[0067] In some embodiments, the wall thickness of the cavity 202 is 2-5 mm.

[0068] In some embodiments, the total length of the air intake duct 201 is ≥ 1200 mm.

[0069] In some embodiments, it also includes an air inlet 1, which is located at the bottom of the tooling, and the air inlet 1 is connected to the air inlet end of the carbon source gas release device 2.

[0070] In some embodiments, a preform placement platform is further included at the bottom of the tooling, and a through hole is provided at the center of the preform placement platform, and the through hole is used to place the carbon source gas release device 2 .

[0071] In some embodiments, the cavity 202 on the carbon source gas releasing device 2 is higher than the upper surface of the preform placing table.

[0072] In some embodiments, the bottom of the preform group to be processed is a guide layer 4 .

[0073] In some embodiments, a furnace shell 6 is further included; in some embodiments, an air outlet 7 is disposed on the top of the furnace shell 6 .

[0074] In some embodiments, the guide gasket 401 is a carbon guide gasket; in some embodiments, the guide gasket 401 is made of graphite.

[0075] Example 2

[0076] This embodiment provides a carbon-carbon composite material and a preparation method thereof, using the chemical vapor infiltration process tooling described in Embodiment 1, specifically comprising:

[0077] A preform group to be processed, wherein a through hole penetrating the preform group to be processed is provided at the center of the preform group to be processed; the preform group to be processed comprises alternately stacked preform layers 3 and guide layers 4; the preform layer 3 comprises preforms to be processed; the guide layer 4 comprises 6 guide pads 401 evenly laid between adjacent preform layers 3, an air flow channel is formed between adjacent guide pads 401, the two ends of the guide pads 401 are respectively located at the inner edge 301 of the preform layer and the outer edge 302 of the preform layer, the number of guide pads 401 laid in each guide layer 4 is the same, and the guide pads 401 laid in each guide layer 4 overlap in the vertical direction. The bottom of the preform group to be processed is the guide layer 4.

[0078] A carbon source gas release device 2, the carbon source gas release device 2 includes a gas outlet end, the gas outlet end is located at the bottom of the through hole of the preform group to be processed, and the gas outlet end includes a hollow cavity 202, and the side wall of the cavity 202 is provided with a first hole and a second hole arranged alternately, and the cavity 202 is higher than the upper surface of the preform placement table. The gas outlet end is connected to the gas inlet end through a spiral gas inlet pipe 201, and the gas inlet end is connected to the gas inlet port 1.

[0079] The gas path baffle plate 5 covers the top of the preform group to be processed, helping to prolong the residence time of the carbon source gas in the preform.

[0080] The preform placement platform is located at the bottom of the tooling, and the center of the preform placement platform has a through hole, on which the carbon source gas release device 2 is placed.

[0081] The furnace shell 6 has a gas outlet 7 at the top.

[0082] The wall thickness of the cavity 202 on the carbon source gas release device 2 used is 4 mm, the length of the spiral air inlet pipe 201 is 1400 mm, the number ratio of the first holes to the second holes is 1:1, the diameter ratio of the first holes to the second holes is 2:1, and the diameter of the first hole is 6 mm.

[0083] The guide gasket 401 used is made of graphite, has an arc shape, a thickness of 4 mm, and a width of 15 mm. At the intersection of the guide gasket 401 and the inner edge 301 of the preform layer, the angle ∠α between the tangent of the guide gasket 401 and the radial position of the inner edge 301 of the preform layer is 100°.

[0084] During assembly, the carbon source gas release device 2 is first placed in the through hole at the center of the preform placement table, and then the guide layer 4 and the preform layer 3 are stacked on the preform placement table in sequence, and finally 9 layers of preform layers 3 and 10 layers of guide layers 4 are stacked, and then the gas path baffle plate 5 is covered thereon.

[0085] In this embodiment, the target density of the preform is 1.75 g / cm 3 During the preparation, the temperature is controlled at 1000°C, the furnace pressure is 5kPa, the carbon source gas enters the carbon source gas release device 2 through the air inlet 1, is preheated in the air inlet pipe 201, and then enters the tooling for chemical vapor infiltration process through the holes on the side wall of the cavity 202. The specific preparation method includes the following steps:

[0086] (1) The first stage: using natural gas and propane with a gas flow ratio of 4:1 as the carbon source gas, the total gas flow rate is 50L / min, the carbon source utilization rate is 35%, and the preform is densified to 1.2g / cm 3 ; Second stage: Use natural gas and propane with a gas flow ratio of 3:1 as the carbon source gas, with a total gas flow of 25L / min and a carbon source utilization rate of 35%, and continue to increase the density of the preform to 1.6g / cm 3 ; The third stage: using natural gas and propane with a gas flow ratio of 8:1 as the carbon source gas, the total gas flow is 15L / min, the carbon source utilization rate is 15%, the preform is densified to the target density, and a carbon-carbon composite material is obtained.

[0087] (2) Detect the carbon-carbon composite materials obtained in (1), screen out the carbon-carbon composite materials that have not reached the target density, and carry out the fourth stage of densification: use natural gas and propane with a gas flow ratio of 20:1 as the carbon source gas, the total gas flow range is 5L / min, the carbon source utilization rate is 10%, and the density is increased to the target density.

[0088] Example 3

[0089] This embodiment provides a carbon-carbon composite material and a preparation method thereof. The preform is densified using the chemical vapor infiltration process tooling described in Example 2 to a target density of 1.5 g / cm 3 During the preparation, the temperature is controlled at 950°C, the furnace pressure is 2kPa, the carbon source gas enters the carbon source gas release device 2 through the air inlet 1, is preheated in the air inlet pipe 201, and then enters the tooling for chemical vapor infiltration process through the holes on the side wall of the cavity 202. The specific preparation method includes the following steps:

[0090] (1) The first stage: using natural gas and propane with a gas flow ratio of 5:1 as the carbon source gas, the total gas flow rate is 36L / min, the carbon source utilization rate is 40%, and the preform is densified to 1.1g / cm 3 ; Second stage: Use natural gas and propane with a gas flow ratio of 4:1 as the carbon source gas, with a total gas flow of 18L / min and a carbon source utilization rate of 30%, and continue to increase the density of the preform to 1.5g / cm 3 .

[0091] Example 4

[0092] This embodiment provides a carbon-carbon composite material and a preparation method thereof. The preform is densified using the chemical vapor infiltration process tooling described in Example 2 to a target density of 1.3 g / cm 3 During the preparation, the temperature is controlled at 1100°C, the furnace pressure is 10 kPa, the carbon source gas enters the carbon source gas release device 2 through the air inlet 1, is preheated in the air inlet pipe 201, and then enters the tooling for chemical vapor infiltration process through the holes on the side wall of the cavity 202. The specific preparation method includes the following steps:

[0093] Natural gas and propane with a gas flow ratio of 5:1 were used as carbon source gases, with a total gas flow of 55 L / min and a carbon source utilization rate of 40%. The preform was densified to 1.3 g / cm 3 .

[0094] Example 5

[0095] The present embodiment provides a carbon-carbon composite material and a preparation method thereof, the only difference from Example 2 is that the guide layer 4 includes 8 guide gaskets 401 uniformly arranged between adjacent preform layers 3, the wall thickness of the cavity 202 on the carbon source gas release device 2 used is 2 mm, the length of the spiral air intake pipe 201 is 1200 mm, the number ratio of the first holes and the second holes is 1:1, the diameter ratio of the first holes and the second holes is 2.5:1, and the diameter of the first hole is 4 mm; the material of the guide gasket 401 used is graphite, the shape is arc-shaped, the thickness is 6 mm, the width is 10 mm, and at the intersection of the guide gasket 401 and the inner edge 301 of the preform layer, the angle ∠α between the tangent of the guide gasket 401 and the radial position of the inner edge 301 of the preform layer is 90°.

[0096] Example 6

[0097] The present embodiment provides a carbon-carbon composite material and a preparation method thereof, the only difference from Example 2 is that the guide layer 4 includes 5 guide gaskets 401 uniformly arranged between adjacent preform layers 3, the wall thickness of the cavity 202 on the carbon source gas release device 2 used is 5 mm, the length of the spiral air intake pipe 201 is 1200 mm, the number ratio of the first holes and the second holes is 1:1, the diameter ratio of the first holes and the second holes is 1.5:1, and the diameter of the first hole is 7 mm; the material of the guide gasket 401 used is graphite, the shape is arc-shaped, the thickness is 2 mm, the width is 20 mm, and at the intersection of the guide gasket 401 and the inner edge 301 of the preform layer, the angle ∠α between the tangent of the guide gasket 401 and the radial position of the inner edge 301 of the preform layer is 140°.

[0098] Example 7

[0099] This embodiment provides a carbon-carbon composite material and a preparation method thereof, which differs from Embodiment 2 only in the specific preparation method:

[0100] (1) The first stage: using natural gas and propane with a gas flow ratio of 5:1 as the carbon source gas, the total gas flow rate is 60L / min, the carbon source utilization rate is 30%, and the preform is densified to 1.3g / cm 3 ; Second stage: Use natural gas and propane with a gas flow ratio of 4:1 as the carbon source gas, with a total gas flow of 36L / min and a carbon source utilization rate of 40%, and continue to increase the density of the preform to 1.7g / cm 3 ; The third stage: using natural gas and propane with a gas flow ratio of 5:1 as the carbon source gas, the total gas flow rate is 10L / min, the carbon source utilization rate is 25%, the preform is densified to the target density, and a carbon-carbon composite material is obtained.

[0101] (2) Testing the carbon-carbon composite materials obtained in (1), screening out the carbon-carbon composite materials that have not reached the target density, and performing the fourth stage of densification: using natural gas and propane with a gas flow ratio of 10:1 as the carbon source gas, with a total gas flow range of 10L / min and a carbon source utilization rate of 5%, to densify to the target density.

[0102] Example 8

[0103] This embodiment provides a method for preparing a carbon-carbon composite material. Compared with Embodiment 2, the only difference is that in the chemical vapor infiltration process tooling used, the guide plate 401 is straight instead of arc-shaped, and the position of the straight guide plate 401 is the position of the chord corresponding to the arc-shaped guide plate 401.

[0104] Example 9

[0105] This embodiment provides a carbon-carbon composite material and a preparation method thereof. The only difference from Embodiment 2 is that natural gas with a total gas flow rate of 30 L / min is used as the carbon source gas throughout the process.

[0106] Comparative Example 1

[0107] This comparative example provides a method for preparing a carbon-carbon composite material. Compared with Example 9, the only difference is that the preform 3 is directly stacked in the furnace for subsequent densification operation.

[0108] Comparative Example 2

[0109] This comparative example provides a method for preparing a carbon-carbon composite material. Compared with Example 2, the only difference is that the preform 3 is directly stacked in the furnace for subsequent densification operation.

[0110] Comparative Example 3

[0111] This comparative example provides a method for preparing a carbon-carbon composite material. Compared with Example 2, the difference is that in the chemical vapor infiltration process tooling used, no carbon source gas release device 2 is used, and the carbon source gas directly enters the tooling through the air inlet 1; during the densification process, at the 150th hour, the maximum density difference between the carbon-carbon composite semi-finished product with the highest density at the high layer and the carbon-carbon composite semi-finished product with the lowest density at the low layer has reached 0.504 g / cm 3 , it is necessary to take out all the semi-finished carbon-carbon composite materials and reload the furnace from bottom to top according to the density from low to high. The operation of taking out the semi-finished carbon-carbon composite materials and reloading the furnace needs to be repeated at the 300th and 400th hours to make the density of the final carbon-carbon composite material as uniform as possible.

[0112] Comparative Example 4

[0113] This comparative example provides a method for preparing a carbon-carbon composite material. Compared with Example 2, the only difference is that the air path baffle 5 is not used.

[0114] Test Example 1

[0115] The time taken to prepare the carbon-carbon composite material in the examples and comparative examples was recorded. The time taken to prepare the carbon-carbon composite material in Example 8 and Comparative Example 1 was the time taken for about 95% of the carbon-carbon composite material to reach the target density.

[0116] The densification efficiency and carbon source utilization rate of the carbon-carbon composite materials prepared in the examples and comparative examples were calculated. The densification efficiency is the density increment of the product per unit time; the carbon source utilization rate = product weight gain / total carbon source weight per cycle.

[0117] The density uniformity of the single carbon-carbon composite materials prepared in the test examples and comparative examples is tested as follows: take a carbon-carbon composite material, divide it into 6 equal parts with the center of a circle as the center, take a group of samples radially in the middle of each part, each group has 4 sample points, and the size is a square of 20 mm×20 mm. Three samples with a height of 6 mm are cut longitudinally from each sample point, for a total of 72 samples, weigh their volume and mass, and calculate the theoretical average density, and use the maximum density-minimum density of the sample block as a reference for characterizing the density uniformity of the carbon-carbon composite material.

[0118] The results are shown in Table 1.

[0119] Table 1

[0120]

[0121]

[0122] As can be seen from Table 1, the densification efficiency and carbon source utilization of Examples 2 to 8 are better than those of Comparative Example 1 which does not use the tooling in this application and the densification treatment method in this application, and Comparative Example 2 which does not use the tooling in this application but uses the densification treatment method in this application. Among them, because the deposition efficiency on the surface of the preform is better than that on the core of the preform during the densification treatment process, and the atmospheric flow deposition will aggravate this process, the density uniformity of Examples 3 and 4 is poor when the densification reaches the target density. Example 9 uses the tooling in this application, but does not use the densification treatment method in this application. Only 30L / min of natural gas is used as the carbon source gas. Due to the low carbon content in natural gas, objective reasons lead to a long preparation time. However, compared with Comparative Example 1 which does not use the tooling in this application and the densification treatment method in this application, it can be seen that the preparation time, densification efficiency, carbon source utilization rate, and density uniformity of Example 9 still have advantages. The tooling in this application does have the effect of shortening the preparation time, improving the densification efficiency, carbon source utilization rate, and density uniformity. In Comparative Example 2, the tooling in this application is not used but the densification treatment method in this application is used. In theory, the densification treatment method in this application has a high densification efficiency, and the carbon source gas is mainly deposited by diffusion inside the preform. Therefore, without using the tooling of this application, the surface of the preform is prone to sealing, thereby affecting the preparation process, and the density uniformity of the obtained carbon-carbon composite material is also poor. Although the preparation time of Comparative Example 3 is not long, the densification efficiency and carbon source utilization rate are also good, according to its preparation method, it is known that without using the carbon source gas release device, the preparation process needs to be stopped frequently, the carbon-carbon composite semi-finished product is taken out to test the density, and the furnace is reloaded according to the density. The process is cumbersome and not suitable for large-scale preparation. In Comparative Example 4, the gas path baffle 5 is not used. Due to the rapid escape of the carbon source gas, the preparation time is long, and the densification efficiency, carbon source utilization rate, and density uniformity are poor.

[0123] Test Example 2

[0124] The mechanical properties of the carbon-carbon composite materials obtained in the test examples and comparative examples are as follows: the tensile properties refer to the standard HB.5434.9-2004, the compression properties refer to the standard HB.5434.5, the bending properties refer to the standard HB.5434.6, and the shear properties refer to ASTM D2344. The results are shown in Table 2. The mechanical properties of the carbon-carbon composite materials obtained in Examples 5 and 6 are similar to those in Example 2 and are not specifically given. It can be seen from Table 2 that the mechanical properties of the carbon-carbon composite materials obtained in the examples of the present application are good.

[0125] Table 2

[0126]

[0127]

[0128] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A tooling for chemical vapor infiltration process, characterized in that: include: A preform group to be processed, wherein a through hole penetrating the preform group to be processed is provided at the center of the preform group to be processed; the preform group to be processed comprises alternately stacked preform layers and guide layers; the preform layers comprise preforms to be processed; the guide layers comprise a plurality of guide pads uniformly arranged between adjacent preform layers, and air flow channels are formed between adjacent guide pads; A carbon source gas releasing device, the carbon source gas releasing device comprising a gas outlet end, the gas outlet end being located at the bottom of the through hole of the preform group to be processed; A gas path baffle plate covers the top of the preform group to be processed.

2. The chemical vapor infiltration process tooling according to claim 1, characterized in that: The guide gasket is in the shape of at least one of an arc shape and a straight line shape; the two ends of the guide gasket are respectively located at the inner edge of the preform layer and the outer edge of the preform layer; optionally, the guide gasket is in the shape of an arc; And / or, each guide layer includes 5 to 8 uniformly laid guide pads; and / or, the number of guide pads laid in each guide layer is the same, and the guide pads laid in each guide layer overlap in the vertical direction; And / or, the guide gasket is in an arc shape, and at the intersection of the guide gasket and the inner edge of the preform layer, the angle between the tangent of the guide gasket and the radial direction of the inner edge of the preform is 90° to 140°; And / or, the guide gasket has a thickness of 2 to 6 mm and a width of 10 to 20 mm.

3. The chemical vapor infiltration tooling according to claim 1 or 2, characterized in that: The gas outlet end of the carbon source gas release device comprises a hollow cavity, and the side wall of the cavity is provided with holes; the gas outlet end is connected to the gas inlet end through a spiral gas inlet pipe; And / or, the holes include first holes and second holes arranged alternately; the diameter ratio of the first holes to the second holes is 1.5-2.5:1; Optionally, the diameter of the first hole ranges from 4 to 7 mm; optionally, the number ratio of the first hole to the second hole is 1:0.8 to 1.2; further optionally, the diameter ratio of the first hole to the second hole is 2:1; And / or, the wall thickness of the cavity is 2 to 5 mm; And / or, the total length of the air intake duct is ≥1200 mm.

4. The chemical vapor infiltration tooling according to any one of claims 1 to 3, characterized in that: It also includes an air inlet, which is located at the bottom of the tooling and is connected to the air inlet end of the carbon source gas release device; And / or, it also includes a preform placement table located at the bottom of the tooling, the preform placement table has a through hole at the center, and the through hole is used to place the carbon source gas release device; optionally, the cavity of the carbon source gas release device is higher than the upper surface of the preform placement table; And / or, the bottom of the preform group to be processed is a guide layer; And / or, further comprising a furnace shell; optionally, an air outlet is provided on the top of the furnace shell; And / or, the guide gasket is a carbon guide gasket; optionally, the material of the guide gasket is graphite.

5. A method for preparing a carbon-carbon composite material, characterized in that: The steps include: Step 1) alternately stacking preform layers and guide layers in a furnace body to form a preform group to be processed; the preform layers include preforms to be processed; the guide layers include a plurality of guide pads evenly arranged between adjacent preform layers, and air flow channels are formed between adjacent guide pads; Step 2) using a gas path baffle to cover the top of the preform group to be processed; Step 3) Introducing carbon source gas into the bottom of the preform group to be processed to perform densification treatment on the preform group to be processed so that the density of the preforms to be processed reaches the target density.

6. The preparation method according to claim 5, characterized in that: The densification treatment method comprises: using natural gas and propane with a gas flow ratio of 3 to 12:1 as carbon source gas, the preparation temperature is 900 to 1100° C., and the furnace chamber pressure during the preparation process is greater than 0 kPa and less than or equal to 10 kPa; And / or, the target density is > 1.7 g / cm 3 The densification treatment includes: in the first stage, natural gas and propane with a gas flow ratio of 4 to 5:1 are used as carbon source gases, the total gas flow range is 36 to 60 L / min, the carbon source utilization rate is 30% to 40%, and the preform is densified to 1.1 to 1.3 g / cm 3 In the second stage, natural gas and propane with a gas flow ratio of 3 to 4:1 are used as carbon source gases, the total gas flow range is 18 to 36 L / min, the carbon source utilization rate is 30% to 40%, and the preform is densified to 1.6 to 1.7 g / cm 3 In the third stage, natural gas and propane with a gas flow ratio of 5 to 10:1 are used as carbon source gases, the total gas flow range is 10 to 18 L / min, and the carbon source utilization rate is 15% to 25%, and the preform is densified to the target density; And / or, the target density of the carbon-carbon composite material is 1.3-1.7 g / cm 3 And does not include 1.3g / cm 3 The densification treatment includes: in the first stage, natural gas and propane with a gas flow ratio of 4 to 5:1 are used as carbon source gases, the total gas flow range is 36 to 60 L / min, and the carbon source utilization rate is 30% to 40%, and the preform is densified to 1.1 to 1.3 g / cm 3 In the second stage, natural gas and propane with a gas flow ratio of 3 to 4:1 are used as carbon source gases, the total gas flow range is 18 to 36 L / min, and the carbon source utilization rate is 30% to 40%, and the preform is densified to the target density; And / or, the target density of the carbon-carbon composite material is ≤1.3 g / cm 3 , using natural gas and propane with a gas flow ratio of 4 to 5:1 as the carbon source gas, the total gas flow range is 36 to 60 L / min, and the carbon source utilization rate is 30% to 45%, and the preform is densified to the target density.

7. The preparation method according to claim 6, characterized in that: The method further includes the step of densifying the carbon-carbon composite material obtained after the third stage that does not reach the target density in the fourth stage; optionally, in the fourth stage, natural gas and propane with a gas flow ratio of 10 to 20:1 are used as carbon source gas, the total gas flow range is 5 to 10 L / min, and the carbon source utilization rate is 5% to 15%; And / or, the density of the preform is 0.38-0.6 g / cm 3 .

8. The preparation method according to any one of claims 5 to 7, characterized in that: The preparation is performed using the chemical vapor infiltration process tooling as described in any one of claims 1 to 4; optionally, when assembling the tooling, the carbon source gas release device is placed first, and then the preform is placed.

9. A carbon-carbon composite material, characterized in that: The invention is prepared by the preparation method as claimed in any one of claims 5 or 8, or by using the chemical vapor infiltration process tooling as claimed in any one of claims 1 to 4.

10. Use of the carbon-carbon composite material according to claim 9 in a brake device.

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