A method for processing a carbon / carbon material casing with a length-diameter ratio of 50 to 130

Abstract

A method for processing carbon / carbon material casing with an aspect ratio of 50 to 130, using a single gas phase infiltration process or a combined gas phase infiltration and liquid phase impregnation process for densification; thermal correction is completed during the high temperature treatment stage to avoid the thermal correction during the densification stage due to the obstruction of gas permeation, thereby affecting the densification rate. During the thermal correction, a carbon / carbon plate with the same area as the densified carbon / carbon plate is used as a loading object, and a constant pressure of 10 to 50 g / cm3 is applied to the surface of the densified carbon / carbon plate. 2 Thermal correction achieves deformation of ≤1mm, significantly lower than the ≥4mm deformation of existing technologies. A three-stage machining process combined with precision turning minimizes deformation of the carbon / carbon sheet material. By adjusting the turning parameters, the outer diameter accuracy of the casing is achieved to ±0.3mm, and the deep hole accuracy to ±0.05mm. This invention eliminates the need for auxiliary tooling, meets dimensional requirements after machining, and offers a simple process, strong operability, and excellent application results.

Description

Technical Field

[0001] The invention relates to a preparation and processing technology of a slender rod deep hole material, in particular to a method for processing a carbon / carbon material sleeve with an aspect ratio of 50-130. Technical Background

[0002] With the rapid increase in installed capacity in the photovoltaic industry, protective sleeves and gas guide sleeves are increasingly used in equipment upgrades. These slender, long-rod carbon / carbon composite parts play a key role in protecting thermocouples and supplying and exhausting gas. To achieve the functionality of these parts, the sleeves are typically designed with a central through-hole or central blind-hole structure. These sleeves have an aspect ratio of 50 to 130. This large aspect ratio and poor rigidity make the machining process prone to vibration and cutting deformation, resulting in dimensional deviations. Furthermore, the carbon / carbon blanks of the sleeves, which are often constructed from long strips of sheet material, are susceptible to significant deformation during the densification process. Therefore, both the initial densification of the carbon / carbon sheet material and the subsequent machining of the sleeve's outer diameter and deep holes present a high degree of difficulty.

[0003] Yang Hao applied for a dual-purpose tool for carbonizing and correcting carbon-carbon plates, patent number CN213894913U. The tool needs to be designed with corresponding size correction tooling according to the specifications of carbonized and graphitized carbon / carbon plates. The number of toolings prepared is large and the production cost is high. During the correction process, the tooling applies pressure control to the surface of the carbon / carbon plate through a limit block. The applied pressure value is not quantified, which can easily cause overload and cause the thickness of the carbon / carbon plate to exceed the tolerance.

[0004] Zhang Shiqi applied for an auxiliary device for turning the outer circle of a slender rod workpiece, patent number CN215746424U, which uses the addition of an auxiliary device for turning the outer circle of a slender rod to improve the turning rigidity of the slender rod and increase the turning dimensional accuracy. The key point of this device is to design a copper sleeve at the center position of the device space. The diameter of the copper sleeve is greater than the diameter of the processed rod by 0.01 to 0.20 mm, which only meets the processing requirements of slender rods of certain sizes. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology in the process of densification of carbon / carbon plates, such as large deformation and easy deviation from tolerance in the subsequent processing of sleeves with an aspect ratio of 50 to 130, the present invention proposes a method for processing carbon / carbon material sleeves with an aspect ratio of 50 to 130.

[0006] The specific process of the present invention is:

[0007] Step 1: Prepare the plate preform:

[0008] The plate preform is prepared by three-dimensional integral needling.

[0009] A layer of flat fabric and a layer of mesh are alternately stacked at 90 degrees and needle-punched longitudinally to form a three-dimensional integral needle-punched preform of the board. The number of layers of the preform is 14 to 16 layers / cm, and the volume density of the preform is 0.40 to 0.50 g / cm 3 .

[0010] Step 2, densification:

[0011] The densification process adopts a single gas phase infiltration process or a composite process of gas phase infiltration + liquid phase impregnation.

[0012] The single vapor infiltration process is to densify the three-dimensional integral needle-punched preform of the plate by using a chemical vapor infiltration method.

[0013] The composite process uses chemical vapor infiltration + liquid phase impregnation method to densify the three-dimensional integral needle-punched preform of the plate. First, the prepared plate preform is placed in a chemical vapor deposition furnace for chemical vapor infiltration densification; when the chemical vapor infiltration densification is completed, the carbon / carbon plate densified by chemical vapor infiltration is transferred to an impregnation furnace for liquid phase impregnation densification.

[0014] A densified carbon / carbon sheet is obtained.

[0015] When a single vapor infiltration process is used, the prepared plate preform is placed in a chemical vapor deposition furnace, evacuated to a furnace pressure of ≤1500Pa, and maintained at this pressure for 2 to 10 hours. When the furnace pressure is ≤3000Pa, power is applied to heat the chemical vapor deposition furnace to the deposition temperature for deposition, with the deposition temperature being 1000 to 1100°C, the natural gas flow rate being 100 to 150 SLM, and the deposition time being 200 to 300 hours. A carbon / carbon plate densified by chemical vapor infiltration is obtained; the volume density of the carbon / carbon plate is ≥1.40g / cm 3 .

[0016] When a composite process is used, the chemical vapor infiltration densification in the composite process is to place the prepared plate preform in a chemical vapor deposition furnace, evacuate the furnace to a pressure of ≤1500Pa, and maintain the pressure for 2 to 10 hours. When the furnace pressure is ≤3000Pa, power is applied to heat the chemical vapor deposition furnace to the deposition temperature for deposition. The deposition temperature is 950 to 1050°C, the natural gas flow rate is 40 to 80 SLM, and the deposition time is 100 to 200 hours. The carbon / carbon plate densified by chemical vapor infiltration is obtained; the volume density of the carbon / carbon plate is 0.8 to 1.1 g / cm 3 .

[0017] The liquid phase impregnation process in the composite process is to transfer the carbon / carbon sheet densified by chemical vapor infiltration into an impregnation furnace for repeated impregnation. The liquid phase impregnation process includes impregnation-curing-carbonization, specifically:

[0018] The impregnation furnace is vacuumized to a pressure of ≤-0.092 MPa, and the pressure is maintained for 4 to 12 hours. After the pressure maintenance is completed, a carbon / carbon plate that has been impregnated once is obtained; the carbon / carbon plate that has undergone the single impregnation is placed in an oven at 120 to 160° C. for curing for 2 to 4 hours to obtain a carbon / carbon plate that has undergone the single curing; the carbon / carbon plate that has undergone the single curing is placed in a carbonization furnace for carbonization at a carbonization temperature of 700 to 900° C. for a carbonization time of 2 to 4 hours to obtain a carbon / carbon plate that has undergone the single liquid phase impregnation.

[0019] The carbon / carbon plate obtained after the first liquid phase impregnation is placed in the impregnation furnace again, and the first impregnation-curing-carbonization process is repeated to perform a second liquid phase impregnation, thereby obtaining a carbon / carbon plate that has undergone the second liquid phase impregnation.

[0020] Repeat the secondary liquid phase impregnation process to repeatedly impregnate the carbon / carbon sheet to increase its density until the bulk density of the carbon / carbon sheet is ≥1.40 g / cm 3 Complete the composite densification. Obtain the carbon / carbon sheet densified by the chemical vapor infiltration method + liquid phase impregnation composite process. The volume density of the carbon / carbon sheet is ≥1.40g / cm 3 .

[0021] Step 3, thermal correction:

[0022] Take another carbon / carbon plate as a pressurizing object; the contact area between the pressurizing object and the densified carbon / carbon plate is equal. Place the pressurizing object on the surface of the densified carbon / carbon plate and make them fit together. Apply 10-50g / cm 2 pressure.

[0023] The pressed carbon / carbon sheet is placed in a high temperature furnace for thermal correction through heat treatment.

[0024] The process parameters for the single-process densified carbon / carbon sheet heat treatment are as follows: evacuate the furnace to a pressure of ≤1500 Pa and maintain the vacuum for 4-12 hours. When the furnace pressure is ≤3000 Pa, power is applied. Simultaneously, the high-temperature furnace is heated at a rate of 4-8°C / min to 2100-2400°C and maintained at that temperature for 4-8 hours. After the temperature is maintained, the sheet is cooled to room temperature in the furnace. This results in a thermally corrected carbon / carbon sheet.

[0025] The heat treatment process parameters for the composite densified carbon / carbon sheet are as follows: vacuum is evacuated to a furnace pressure of ≤1500 Pa, then maintained for 4-12 hours. When the furnace pressure is ≤3000 Pa, power is applied, and the high-temperature furnace is heated at a rate of 2-6°C / min to 1800-2100°C and maintained for 4-8 hours. After the temperature is maintained, the sheet is cooled to room temperature in the furnace. This results in a thermally corrected carbon / carbon sheet.

[0026] Step 4, sectioning:

[0027] The densified carbon / carbon sheet is cut to obtain a rectangular carbon / carbon sleeve blank with length×width×height=a×b×c.

[0028] During cutting, the machine tool speed is 4000~6000r / min and the feed amount is 0.3~0.6mm.

[0029] Step 5, turning:

[0030] Positioning holes are machined at the geometric centers of the end faces at both ends of the carbon / carbon sleeve blank.

[0031] The carbon / carbon casing blank is clamped on a lathe and its surface is evenly divided into three sections along its length for lathing. The first section is first machined to a diameter that reaches the upper limit of the designed size. The machined first section is clamped in a lathe chuck as a clamping end, and the second section is subsequently machined. The three sections are sequentially machined to obtain a carbon / carbon casing preform blank.

[0032] The surface of the carbon / carbon casing preform blank is obtained by precision lathing according to the drawing to obtain a carbon / carbon casing preform with a specification of D×a, where D is the diameter of the carbon / carbon casing preform.

[0033] During turning, the lathe spindle speed is 500~1000r / min, and the feed amount is 0.1~0.3mm.

[0034] Step 6, Drilling Deep Holes:

[0035] The obtained carbon / carbon sleeve preform is drilled with sealed chip removal drilling to produce a deep hole, thereby obtaining a carbon / carbon sleeve with a d×h deep hole, wherein d is the inner diameter of the carbon / carbon sleeve.

[0036] When drilling deep holes, the drill speed is 1600~2000r / min and the feed amount is 6~10mm.

[0037] Step 7, preparation of CVD coating:

[0038] The obtained carbon / carbon sleeve is placed in a chemical vapor deposition furnace to prepare a CVD coating. The specific process is:

[0039] The deposition furnace was evacuated to a pressure of ≤1500 Pa and maintained for 2 to 10 hours. During this period, when the pressure reached ≤3000 Pa, the chemical vapor deposition furnace was heated at a rate of 1 to 2°C / min to the coating temperature for CVD coating. The coating temperature was 1100 to 1200°C, the natural gas flow rate was 100 to 150 SLM, and the coating time was 50 to 100 hours. Natural gas was used as the protective atmosphere and source gas during the CVD coating. A carbon / carbon sleeve with a CVD coating was obtained.

[0040] At this point, the processing of the carbon / carbon material sleeve with an aspect ratio of 50 to 130 is completed.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] Beneficial effect 1: When the existing technology does not use tooling for correction, the deformation is ≥4mm; when the existing technology uses tooling for correction, it mainly controls the pressure on the surface of the carbon / carbon plate by limiting the block, but the pressure value is not clear, so the pressure overload will cause the thickness size to exceed the tolerance; the existing technology needs to design tooling of corresponding size according to the carbon / carbon plate to be corrected, which makes the number of tooling preparations large and the cost high. The present invention uses a carbon / carbon plate with the same area as the densified carbon / carbon plate as the loading object, and applies a constant pressure of 10 to 50g / cm on the surface of the densified carbon / carbon plate. 2 Thermal correction is performed, and the deformation amount is ≤1mm; the present invention adopts the carbon / carbon plate with the same area as the loading object, which is easy to prepare and reduces the cost of tooling design and tooling preparation; the present invention completes the thermal correction in the high-temperature treatment stage, avoiding the situation in the densification stage where the carbon / carbon plate with the same area as the loading object is closely attached to the surface of the carbon / carbon plate, hindering the penetration of gas, thereby affecting the densification rate.

[0043] Beneficial effect 2: The existing technologies all use auxiliary devices to perform one-stage processing to solve the bending and vibration caused by uneven cutting force due to insufficient rigidity of the sleeve with a length-to-diameter ratio of 50 to 130, so as to ensure the tolerance of the outer diameter size of the sleeve after processing. The one-stage turning method adopted, the surface of the sleeve obtained has obvious bamboo-shaped or twisted steps, and the outer diameter dimensions at different positions are all out of tolerance. The present invention adopts a processing method that combines three stages + fine turning. Under the premise of reducing the deformation of the carbon / carbon plate, by adjusting the turning parameters, the outer diameter accuracy of the sleeve is ±0.3mm and the deep hole accuracy is ±0.05mm. The present invention does not require the design of auxiliary tooling, and meets the dimensional requirements after processing. The processing technology proposed by the present invention has a simple operation process, strong operability, and good application effect.

[0044] Table 1 Comparison of dimensional tolerances after processing by different processing methods

[0045]

[0046] BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the technical solution for preparing carbon / carbon material sleeves.

[0048] Figure 2 This is the morphology of a carbon / carbon material casing with deep holes.

[0049] Figure 3This is the macroscopic morphology of the carbon / carbon material casing.

[0050] Figure 4 It is a flow chart of the present invention DETAILED DESCRIPTION

[0051] The present invention adopts a single chemical vapor infiltration process or a composite process combining chemical vapor infiltration and liquid phase impregnation to prepare a carbon / carbon material casing with an aspect ratio of 50 to 130; the specific process is:

[0052] When a single chemical vapor infiltration process is used to prepare a carbon / carbon material casing with an aspect ratio of 50 to 130

[0053] Step 1, plate prefab:

[0054] Prepare a three-dimensional integral needle-punched preform of a plate.

[0055] According to the conventional method, a layer of non-woven fabric and a layer of mesh are alternately stacked at 90 degrees and longitudinally needled to form a three-dimensional integral needle-punched preform of the plate. The number of layers of the preform is 14 to 16 layers / cm, and the volume density of the preform is 0.40 to 0.50 g / cm 3 .

[0056] Step 2, densification:

[0057] The prepared plate preform is placed in a chemical vapor deposition furnace, evacuated to a furnace pressure of ≤1500Pa, and maintained at this pressure for 2 to 10 hours; when the furnace pressure is ≤3000Pa, the chemical vapor deposition furnace is powered on to heat up to the deposition temperature for deposition, with the deposition temperature being 1000 to 1100°C, the natural gas flow rate being 100 to 150 SLM, and the deposition time being 200 to 300 hours. A carbon / carbon plate densified by chemical vapor infiltration is obtained, with a volume density of ≥1.40 g / cm 3 . A densified carbon / carbon sheet is obtained.

[0058] Step 3, thermal correction:

[0059] Take another carbon / carbon plate as a pressurizing object; the contact area between the pressurizing object and the densified carbon / carbon plate is equal. Place the pressurizing object on the surface of the densified carbon / carbon plate and make them fit together. Apply 10-50g / cm 2 pressure.

[0060] The pressurized carbon / carbon sheet is placed in a high-temperature furnace and heat-treated according to conventional methods for thermal correction. The heat treatment process parameters are as follows: evacuate the furnace to a pressure of ≤1500 Pa and maintain the vacuum for 4-12 hours. When the furnace pressure is ≤3000 Pa, power is applied. Simultaneously, the high-temperature furnace is heated at a rate of 4-8°C / min to 2100-2400°C and maintained at this temperature for 4-8 hours. After the temperature is maintained, the sheet is cooled to room temperature in the furnace. This results in a thermally corrected carbon / carbon sheet.

[0061] Step 4, sectioning:

[0062] A diamond cutting tool is used to cut the carbon / carbon plate along its length direction, with a machine speed of 4000-6000 r / min and a feed of 0.3-0.6 mm to obtain a rectangular carbon / carbon sleeve blank with a length×width×height=a×b×c.

[0063] In this embodiment, a=800 mm, b=18 mm, and c=18 mm.

[0064] Step 5, turning:

[0065] A handheld drill is used to machine positioning holes at the geometric centers of the end faces of both ends of the carbon / carbon casing blank, and the depth of the positioning holes is 2 to 5 mm.

[0066] The carbon / carbon casing blank is clamped on a lathe and its surface is lathed in three sections along its length. The first section is first machined to a diameter that reaches the upper limit of the designed size. The first section is then clamped in the lathe chuck with the machined section as the clamping end, and the second section is then machined. The three sections are sequentially machined to obtain a carbon / carbon casing preform blank. The lathe spindle speed is 500 to 1000 rpm, and the feed rate is 0.1 to 0.3 mm.

[0067] The surface of the carbon / carbon casing preform blank is fine-turned according to the drawing. Burrs are removed with sandpaper. The resulting carbon / carbon casing preform has a specification of D×a, where D is the diameter of the carbon / carbon casing preform.

[0068] In this embodiment, D=14 mm, a=800 mm.

[0069] Step 6, Drilling Deep Holes:

[0070] A CNC deep hole drilling DH device is used to drill deep holes in the obtained carbon / carbon casing preform blank using sealed chip removal drilling. The drill speed is 1600-2000 r / min and the feed is 6-10 mm.

[0071] A carbon / carbon sleeve with a deep hole specification of d×h is obtained, wherein d is the inner diameter of the carbon / carbon sleeve.

[0072] In this embodiment, d=8 mm, h=780 mm.

[0073] Step 7, preparation of CVD coating:

[0074] The obtained carbon / carbon sleeve is placed in a chemical vapor deposition furnace to prepare a CVD coating. The specific process is:

[0075] The deposition furnace was evacuated to a pressure of ≤1500 Pa and maintained at this pressure for 2 to 10 hours. During this period, when the pressure reached ≤3000 Pa, the furnace was powered on to raise the temperature to the coating temperature at a rate of 1 to 2°C / min. CVD coating was performed at a coating temperature of 1100 to 1200°C, a natural gas flow rate of 100 to 150 SLM, and a coating time of 50 to 100 hours. Natural gas was used as both the protective atmosphere and the source gas during the CVD coating. A carbon / carbon sleeve with a CVD coating was obtained.

[0076] At this point, the processing of the carbon / carbon material sleeve with an aspect ratio of 50 to 130 is completed.

[0077] Table 1 Process parameters for carbon / carbon casing with aspect ratio of 50 to 130 prepared by chemical vapor infiltration densification process

[0078]

[0079] The present invention adopts a composite densification process combining chemical vapor infiltration and liquid impregnation to prepare a carbon / carbon material casing with an aspect ratio of 50 to 130. The specific process is:

[0080] Step 1, plate prefab:

[0081] Prepare a three-dimensional integral needle-punched preform of a plate.

[0082] According to the conventional method, a layer of non-woven fabric and a layer of mesh are alternately stacked at 90 degrees and longitudinally needled to form a three-dimensional integral needle-punched preform of the plate. The number of layers of the preform is 14 to 16 layers / cm, and the volume density of the preform is 0.40 to 0.50 g / cm 3 .

[0083] Step 2, densification:

[0084] The three-dimensional integral needle-punched preform of the plate is densified by adopting a composite process combining a chemical vapor infiltration method and a liquid phase impregnation method.

[0085] The chemical vapor infiltration densification in the composite process is to place the prepared plate preform in a chemical vapor deposition furnace, evacuate the furnace to a pressure of ≤1500Pa, and maintain the pressure for 2 to 10 hours. When the furnace pressure is ≤3000Pa, power is turned on to heat the chemical vapor deposition furnace to the deposition temperature for deposition. The deposition temperature is 950 to 1050°C, the natural gas flow rate is 40 to 80 SLM, and the deposition time is 100 to 200 hours. The carbon / carbon plate densified by chemical vapor infiltration is obtained, and the volume density of the carbon / carbon plate is 0.8 to 1.1 g / cm 3 .

[0086] The liquid phase impregnation process in the composite process is to transfer the carbon / carbon plate densified by chemical vapor infiltration to an impregnation furnace for repeated impregnation. The liquid phase impregnation process includes impregnation--curing--carbonization, specifically: evacuating the pressure of the impregnation furnace to ≤-0.092MPa, maintaining the pressure for 4 to 12 hours, and obtaining a carbon / carbon plate after the pressure holding is completed; placing the carbon / carbon plate that has been impregnated once in an oven at 120 to 160°C for curing, the curing time is 2 to 4 hours, and obtaining a carbon / carbon plate that has been cured once; placing the carbon / carbon plate that has been cured once in a carbonization furnace for carbonization, the carbonization temperature is 700 to 900°C, and the carbonization time is 2 to 4 hours, and obtaining a carbon / carbon plate that has been impregnated once.

[0087] The carbon / carbon plate obtained after the first liquid phase impregnation is placed in the impregnation furnace again, and the first impregnation-curing-carbonization process is repeated to perform a second liquid phase impregnation, thereby obtaining a carbon / carbon plate that has undergone the second liquid phase impregnation.

[0088] Repeat the secondary liquid phase impregnation process to repeatedly impregnate the carbon / carbon sheet to increase its density until the bulk density of the carbon / carbon sheet is ≥1.40 g / cm 3 Complete the composite densification. Obtain the carbon / carbon sheet densified by the chemical vapor infiltration method + liquid phase impregnation composite process. The volume density of the carbon / carbon sheet is ≥1.40g / cm 3 .

[0089] Step 3, thermal correction:

[0090] Take another carbon / carbon plate as a pressurizing object; the contact area between the pressurizing object and the densified carbon / carbon plate is equal. Place the pressurizing object on the surface of the densified carbon / carbon plate and make them fit together. Apply 10-50g / cm 2 pressure.

[0091] The pressurized carbon / carbon sheet is placed in a high-temperature furnace and heat-treated according to conventional methods for thermal correction. The heat treatment process parameters are as follows: evacuate the furnace to a pressure of ≤1500 Pa and maintain the vacuum for 4-12 hours. When the furnace pressure is ≤3000 Pa, power is applied. Simultaneously, the high-temperature furnace is heated at a rate of 2-6°C / min to 1800-2100°C and maintained at this temperature for 4-8 hours. After the temperature is maintained, the sheet is cooled to room temperature in the furnace. This results in a thermally corrected carbon / carbon sheet.

[0092] Step 4, sectioning:

[0093] A diamond cutting tool is used to cut the carbon / carbon plate along its length direction, with a machine speed of 4000-6000 r / min and a feed of 0.3-0.6 mm to obtain a rectangular carbon / carbon sleeve blank with a length×width×height=a×b×c.

[0094] In this embodiment, a=800 mm, b=18 mm, and c=18 mm.

[0095] Step 5, turning:

[0096] A handheld drill is used to machine positioning holes at the geometric centers of the end faces of both ends of the carbon / carbon casing blank, and the depth of the positioning holes is 2 to 5 mm.

[0097] The carbon / carbon casing blank is clamped on a lathe and its surface is lathed in three sections along its length. The first section is first machined to a diameter that reaches the upper limit of the designed size. The first section is then clamped in the lathe chuck with the machined section as the clamping end, and the second section is then machined. The three sections are sequentially machined to obtain a carbon / carbon casing preform blank. The lathe spindle speed is 500 to 1000 rpm, and the feed rate is 0.1 to 0.3 mm.

[0098] The surface of the carbon / carbon casing preform blank is fine-turned according to the drawing. Burrs are removed with sandpaper. The resulting carbon / carbon casing preform has a specification of D×a, where D is the diameter of the carbon / carbon casing preform.

[0099] In this embodiment, D=14 mm, a=800 mm.

[0100] Step 6, Drilling Deep Holes:

[0101] A CNC deep hole drilling DH device is used to drill deep holes in the obtained carbon / carbon casing preform blank using sealed chip removal drilling. The drill speed is 1600-2000 r / min and the feed is 6-10 mm.

[0102] A carbon / carbon sleeve with a deep hole specification of d×h is obtained, wherein d is the inner diameter of the carbon / carbon sleeve.

[0103] In this embodiment, d=8 mm, h=780 mm.

[0104] Step 7, preparation of CVD coating:

[0105] The obtained carbon / carbon sleeve is placed in a chemical vapor deposition furnace to prepare a CVD coating. The specific process is:

[0106] The deposition furnace was evacuated to a pressure of ≤1500 Pa and maintained at this pressure for 2 to 10 hours. During this period, when the pressure reached ≤3000 Pa, the furnace was powered on to raise the temperature to the coating temperature at a rate of 1 to 2°C / min. CVD coating was performed at a coating temperature of 1100 to 1200°C, a natural gas flow rate of 100 to 150 SLM, and a coating time of 50 to 100 hours. Natural gas was used as both the protective atmosphere and the source gas during the CVD coating. A carbon / carbon sleeve with a CVD coating was obtained.

[0107] At this point, the processing of the carbon / carbon material sleeve with an aspect ratio of 50 to 130 is completed.

[0108] Table 2 Process parameters for preparing carbon / carbon material casing with aspect ratio of 50-130 by chemical vapor infiltration + liquid phase impregnation composite process

[0109]

[0110]

Claims

1. A method for processing a carbon / carbon material casing with an aspect ratio of 50 to 130, characterized in that: The specific process is: Step 1: Prepare the plate preform: Preparation of sheet material preforms by three-dimensional integral needling; Step 2, densification: The densification process adopts a single gas phase infiltration process, or a composite process of gas phase infiltration + liquid phase impregnation; The single vapor infiltration process is to densify the three-dimensional integral needle-punched preform of the plate by using chemical vapor infiltration; The composite process is to densify the three-dimensional integral needle-punched preform of the plate by using a chemical vapor infiltration method and a liquid phase impregnation method. First, the prepared plate preform is placed in a chemical vapor deposition furnace for chemical vapor infiltration densification. After the chemical vapor infiltration densification is completed, the carbon / carbon plate densified by chemical vapor infiltration is transferred to an impregnation furnace for liquid phase impregnation densification. obtaining a densified carbon / carbon sheet; Step 3, thermal correction: Take another carbon / carbon plate as a pressurizing object; the contact area between the pressurizing object and the densified carbon / carbon plate is equal; place the pressurizing object on the surface of the densified carbon / carbon plate and make them fit together, and apply 10-50g / cm 2 pressure; placing the pressurized carbon / carbon sheet into a high-temperature furnace for thermal correction through heat treatment to obtain a thermally corrected carbon / carbon sheet; Step 4, sectioning: The densified carbon / carbon sheet is cut to obtain a rectangular carbon / carbon sleeve blank with a length×width×height=a×b×c; Step 5, turning: Processing positioning holes at the geometric centers of the end faces of both ends of the carbon / carbon sleeve blank; The carbon / carbon casing blank is clamped on a lathe and its surface is machined into three equal sections along its length; the first section is machined first, and its diameter is machined to the upper limit of the designed size; the machined first section is clamped in the lathe chuck as a clamping end, and the second section is machined continuously; the three sections are machined sequentially to obtain a carbon / carbon casing prefabricated tube blank; The surface of the carbon / carbon casing preform blank is obtained by precision turning according to the drawing; a carbon / carbon casing preform with a specification of D×a is obtained; Where D is the diameter of the carbon / carbon sleeve preform; Step 6, Drilling Deep Holes: The obtained carbon / carbon casing is subjected to sealed chip removal drilling to process a deep hole; the drill speed is 1600-2000 r / min, and the feed amount is 6-10 mm; and a carbon / carbon casing having a d×h deep hole is obtained; Where d is the inner diameter of the carbon / carbon sleeve; Step 7, preparation of CVD coating: The obtained carbon / carbon sleeve is placed in a chemical vapor deposition furnace to prepare a CVD coating; The specific process is: The deposition furnace is evacuated to a furnace pressure of ≤1500 Pa and the pressure is maintained for 2 to 10 hours. When the furnace pressure is ≤3000 Pa, power is turned on to heat the chemical vapor deposition furnace at a rate of 1 to 2°C / min to a coating temperature for CVD coating. The coating temperature is 1100 to 1200°C, the natural gas flow rate is 100 to 150 SLM, and the coating time is 50 to 100 hours. During the preparation of the CVD coating, natural gas is used as a protective atmosphere and a gas source. A carbon / carbon sleeve with a CVD coating is obtained. At this point, the processing of the carbon / carbon material sleeve with an aspect ratio of 50 to 130 is completed.

2. The method for processing a carbon / carbon material sleeve with an aspect ratio of 50 to 130 according to claim 1, characterized in that: A layer of flat fabric and a layer of mesh are alternately stacked at 90 degrees and longitudinally needle-punched to form a three-dimensional integral needle-punched preform of the plate; the number of layers of the preform is 14 to 16 layers / cm, and the volume density of the preform is 0.40 to 0.50 g / cm 3 .

3. The method for processing a carbon / carbon material sleeve with an aspect ratio of 50 to 130 according to claim 1, characterized in that: When a single vapor infiltration process is used, the prepared plate preform is placed in a chemical vapor deposition furnace, evacuated to a furnace pressure of ≤1500 Pa, and the pressure is maintained for 2 to 10 hours; when the furnace pressure is ≤3000 Pa, power is applied to heat the chemical vapor deposition furnace to a deposition temperature for deposition, wherein the deposition temperature is 1000 to 1100° C., the natural gas flow rate is 100 to 150 SLM, and the deposition time is 200 to 300 hours; and a carbon / carbon plate densified by chemical vapor infiltration is obtained; the carbon / carbon plate has a volume density of ≥1.40 g / cm 3 .

4. The method for processing a carbon / carbon material sleeve with an aspect ratio of 50 to 130 according to claim 1, characterized in that: When a composite process is adopted, the chemical vapor infiltration densification in the composite process is to place the prepared plate preform in a chemical vapor deposition furnace, evacuate the furnace to a pressure of ≤1500Pa, maintain the pressure for 2 to 10 hours, and when the furnace pressure is ≤3000Pa, power is turned on to heat the chemical vapor deposition furnace to a deposition temperature for deposition, wherein the deposition temperature is 950 to 1050°C, the natural gas flow rate is 40 to 80SLM, and the deposition time is 100 to 200 hours; thereby obtaining a carbon / carbon plate densified by chemical vapor infiltration; the carbon / carbon plate has a volume density of 0.8 to 1.1 g / cm 3 .

5. The method for processing a carbon / carbon material sleeve with an aspect ratio of 50 to 130 according to claim 4, characterized in that: The liquid phase impregnation process in the composite process is to repeatedly impregnate the carbon / carbon sheet transferred to the impregnation furnace; The process of liquid phase impregnation includes impregnation-curing-carbonization, specifically: Evacuate the impregnation furnace so that the pressure is ≤-0.092 MPa, maintain the pressure for 4 to 12 hours, and obtain a carbon / carbon plate after the primary impregnation; place the carbon / carbon plate after the primary impregnation in an oven at 120 to 160° C. for curing for 2 to 4 hours to obtain a carbon / carbon plate after the primary curing; place the carbon / carbon plate after the primary curing in a carbonization furnace for carbonization at a carbonization temperature of 700 to 900° C. for 2 to 4 hours to obtain a carbon / carbon plate after the primary liquid phase impregnation; The obtained carbon / carbon plate after the first liquid phase impregnation is placed in the impregnation furnace again, and the first impregnation-curing-carbonization process is repeated to perform a second liquid phase impregnation; obtaining a carbon / carbon sheet that has undergone secondary liquid phase impregnation; Repeat the secondary liquid phase impregnation process to repeatedly impregnate the carbon / carbon sheet to increase its density until the bulk density of the carbon / carbon sheet is ≥1.40 g / cm 3 Complete composite densification; obtain carbon / carbon sheet densified by chemical vapor infiltration + liquid phase impregnation composite process, carbon / carbon sheet volume density ≥1.40g / cm 3 .

6. The method for processing a carbon / carbon material sleeve with an aspect ratio of 50 to 130 according to claim 1, characterized in that: The process parameters of the single process densified carbon / carbon plate heat treatment are as follows: vacuuming to a furnace pressure of ≤1500Pa and maintaining the vacuum for 4 to 12 hours; when the furnace pressure is ≤3000Pa, power is turned on, and the high-temperature furnace is heated at a rate of 4 to 8°C / min to 2100 to 2400°C and maintained at this temperature for 4 to 8 hours. After the end of the temperature maintenance, the high-temperature furnace is cooled to room temperature. The heat treatment is a step in the thermal correction process.

7. The method for processing a carbon / carbon material sleeve with an aspect ratio of 50 to 130 according to claim 1, characterized in that: The process parameters for heat treatment of the composite process densified carbon / carbon plate are as follows: vacuuming to a furnace pressure of ≤1500Pa and maintaining the vacuum for 4-12 hours; when the furnace pressure is ≤3000Pa, power is turned on and the high-temperature furnace is heated at a rate of 2-6°C / min to 1800-2100°C and maintained at this temperature for 4-8 hours; after the end of the insulation, the plate is cooled to room temperature along with the furnace; The heat treatment is a step in the thermal correction process.

8. The method for processing a carbon / carbon material sleeve with an aspect ratio of 50 to 130 according to claim 1, characterized in that: During cutting, the machine tool speed is 4000~6000r / min and the feed amount is 0.3~0.6mm.

9. The method for processing a carbon / carbon material sleeve with an aspect ratio of 50 to 130 according to claim 1, characterized in that: When drilling deep holes, the drill speed is 1600~2000r / min and the feed amount is 6~10mm.

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