A method for manufacturing a carbon dynamic seal ring

Abstract

The application discloses a preparation method of a carbon dynamic sealing ring, and comprises the following steps: step one, crushing mesophase pitch, then putting the crushed pitch into a mold, and then putting the mold into a foaming reaction device to perform foaming treatment; after the foaming treatment is completed, cooling to room temperature to obtain pitch-based foam carbon precursor; step two, carbonizing the obtained pitch-based foam carbon precursor in a high-temperature carbonization furnace under nitrogen atmosphere protection to obtain pitch foam carbon templates; step three, cutting the pitch foam carbon templates according to the size of the required dynamic sealing ring to obtain a preform for deposition, and then performing surface activation treatment on the preform; step four, performing chemical vapor deposition densification treatment on the foam carbon preform subjected to the surface activation treatment in a deposition furnace; and step five, performing mechanical processing on the deposition-densified original blank according to the size of the required dynamic sealing ring to obtain a ring-shaped carbon dynamic sealing ring. The application has a shorter preparation period and does not have special requirements on raw materials.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of carbon dynamic sealing rings, in particular to a preparation method of a carbon dynamic sealing ring. BACKGROUND

[0002] Aerospace engines work in extreme environments of high temperature, high pressure, high speed and high load, and the reliability of the sealing position is crucial. The performance of the sealing material directly affects the flight safety of the rocket, the service life of the components and the stability of the system. As the core component of the engine, the sealing material must withstand extreme temperature changes, high pressure, microgravity and corrosion, while having high strength, high oxidation resistance, high temperature resistance, good thermal conductivity and stable low friction coefficient. Graphite material is widely used in dynamic sealing elements of aerospace engines due to its light weight, high thermal conductivity, low friction coefficient, high temperature resistance and self-lubricating properties.

[0003] However, the existing high-strength graphite material has encountered challenges in the application of inter-shaft sealing of aerospace engines, especially under the huge centrifugal force generated by high-speed rotation, which puts higher requirements on the tensile strength and friction and wear properties of the sealing material. At the same time, the development needs of liquid oxygen / kerosene engines further exacerbate the requirements for the performance of the sealing material, including low open porosity, high strength, high hardness and impact resistance. Therefore, the development of pyrolytic carbon sealing materials with higher performance to meet these stringent use requirements has become one of the key tasks in the development of liquid oxygen / kerosene engines.

[0004] The existing preparation process of carbon dynamic sealing ring material usually uses ultra-fine particle isotropic graphite powder with a particle size not greater than 1 mu m and high-melting-point pitch or resin as raw materials, and is prepared by high-temperature and high-pressure isostatic pressing technology. This not only puts high requirements on the raw materials, and the preparation of ultra-fine particle graphite is difficult, but also requires strict equipment, which is not suitable for the manufacture of special-shaped components. In view of these problems, the application provides a preparation method of a carbon dynamic sealing ring, that is, pyrolytic carbon is deposited on a porous foam carbon matrix to prepare a high-density, high-strength isotropic pyrolytic carbon block, and then the high-wear-resistant dynamic sealing ring component is processed. This method does not require ultra-fine particle graphite powder as raw material, and eliminates the isostatic pressing process, thereby significantly reducing the preparation cost. SUMMARY

[0005] In view of the defects of the prior art, the purpose of the application is to provide a preparation method of a carbon dynamic sealing ring.

[0006] To achieve the above purpose, the application provides a preparation method of a carbon dynamic sealing ring, comprising the following steps:

[0007] Step one, the mesophase pitch is broken, then the broken pitch is put into the mold, then the mold is put into the foaming reaction device for foaming treatment, after the foaming is finished, it is cooled to room temperature to obtain the pitch-based foam carbon precursor;

[0008] Step two, the obtained pitch-based foam carbon precursor is carbonized in a high-temperature carbonization furnace under the protection of nitrogen atmosphere, and the temperature is kept constant for 4-6 hours to obtain the pitch foam carbon template;

[0009] Step three, according to the size of the required dynamic sealing ring, the pitch foam carbon template is cut to obtain a preform for deposition, and then the preform is subjected to surface activation treatment;

[0010] Step four, the foam carbon preform subjected to surface activation treatment is subjected to chemical vapor deposition densification treatment in a deposition furnace;

[0011] Step five, the deposited and densified raw blank is machined according to the required size of the dynamic sealing ring to obtain a ring-shaped carbon dynamic sealing ring with uniform texture.

[0012] Further, in step three, the surface activation treatment is specifically as follows: the preform is soaked in deionized water, then ultrasonic cleaning is performed to remove dust in the pores of the preform, then the cleaned preform is soaked in a nitric acid solution, the solution is heated to 60-80℃ and kept for 1-3 hours, and finally the preform is cleaned and dried with deionized water for use.

[0013] Further, in step one, the foaming treatment is specifically as follows: first, increase the temperature to 230-270℃ at a rate of 3-8℃ / min, then increase the pressure in the kettle to 2.8-3.3MPa by introducing nitrogen, then increase the temperature to 430-460℃ at a rate of 1-3℃ / min, and keep the temperature for 3-5 hours, in step four, natural gas is used as the carbon source gas and argon-hydrogen mixed gas is used as the carrier gas for deposition and densification.

[0014] Further, in the preparation process of the pitch-based foam carbon precursor, the pitch is broken to 80-120 mesh before foaming to improve the foaming effect and uniformity of the pitch, the pitch breaking process adopts mechanical breaking or ultrasonic breaking technology, the foaming reaction device is a high-pressure kettle to ensure that the pitch can be fully foamed under high temperature and high pressure, the inner wall of the high-pressure kettle is made of corrosion-resistant material to improve the service life and safety of the equipment, such as special ceramics or alloys to prolong the service life of the furnace body, and the high-pressure kettle is provided with multiple layers of heat insulation to reduce external heat loss and protect the operator from high temperature.

[0015] Further, during the carbonization process of the pitch-based foam carbon precursor, the carbonization temperature is 900-1100°C to ensure the carbonization effect and quality of the pitch foam carbon template, the high-temperature carbonization furnace uses a program-controlled temperature system for temperature control to accurately control the carbonization temperature and time, during the surface activation treatment of the preform, the ultrasonic cleaning time is 15-30 minutes to ensure that the dust in the preform holes is effectively removed, the ultrasonic cleaning equipment uses a frequency-adjustable ultrasonic generator to adapt to preforms of different pore sizes, and the concentration of the nitric acid solution is 35%-70% to ensure the activation effect of the preform surface. The nitric acid solution uses a circulating heating system for heating to maintain the uniformity of the solution temperature.

[0016] Further, during the chemical vapor deposition densification process, the deposition temperature is 1500-1700°C under normal pressure or slightly positive pressure to ensure the densification effect and quality of the foam carbon preform, the deposition furnace uses multi-zone temperature control technology to realize temperature gradient control during the deposition process, the ratio of carbon source gas to carrier gas is V 碳源气 :V 载气 =0.1-0.15:1 to ensure the uniformity and efficiency of the deposition densification, the carbon source gas and carrier gas use an accurate flow control system for gas flow control to ensure the accuracy of the gas ratio, and during the chemical vapor deposition densification process, the deposition time is 50-80 hours to ensure that the density of the foam carbon preform reaches 1.85 g / cm³, and the deposition time is monitored and adjusted by the control system to improve the deposition efficiency and product quality.

[0017] Further, the process further includes an environmental monitoring step, a quality control step, and a data recording and analysis step. The quality control step involves quality detection of intermediate products after each preparation stage to ensure the quality and performance of the final product, the environmental monitoring step involves real-time monitoring and control of environmental conditions such as humidity and temperature during the preparation process to ensure the stability of the preparation process and the consistency of the product, and the data recording and analysis step involves recording all parameters and conditions during the preparation process and using data analysis techniques to optimize the preparation process, improve efficiency and product quality, including data collection, data preprocessing and data analysis. First, all parameter and condition data related to the preparation process need to be collected, after collecting the original data, data processing and arrangement are carried out to eliminate abnormal values, missing values and repeated data, ensure the quality and accuracy of the data, and use statistical analysis, machine learning and other methods to analyze the data in depth, extract useful patterns and trends from the cleaned data, and predict future behavior through mathematical models.

[0018] Further, in step two, carbonization is carried out in a high-temperature carbonization furnace under nitrogen atmosphere protection. The nitrogen atmosphere protection can effectively isolate oxygen to prevent the pitch foam carbon template from being oxidized at high temperature, resulting in a decrease in material performance. The system is equipped with a nitrogen purity monitoring device to ensure that the purity of nitrogen entering the autoclave reaches 99.99% or above, thereby minimizing the risk of oxidation. The carbonization furnace is equipped with a gas pressure regulating system, which includes a gas pressure sensor and an electric valve, to accurately control the pressure in the furnace during carbonization, ensuring uniform distribution and stability of the nitrogen atmosphere. The gas pressure sensor in the carbonization furnace can accurately measure the pressure changes during carbonization, ensuring the accuracy of pressure control. The user can set safety limits for gas pressure. Once these limits are exceeded, the system will automatically take measures such as opening the electric valve to release the pressure. At the same time, an integrated alarm system is provided to sound an alarm when the gas pressure exceeds the preset range, reminding the operator to take appropriate measures.

[0019] Further, a carbon dynamic sealing ring is obtained by the above preparation method, and the dynamic sealing ring has the following properties: a bulk density of 1.85 g / cm³, a surface open porosity of less than 0.1%, a compressive strength of more than 360 MPa, and a friction coefficient of less than 0.1, meeting the performance requirements of high-temperature carbon dynamic sealing rings.

[0020] Further, during the preparation of the dynamic sealing ring, the foaming conditions and carbonization conditions of the pitch-based foam carbon precursor are controlled to realize the microstructure control of the dynamic sealing ring. The number of micropores on the surface of the dynamic sealing ring is significantly reduced through chemical vapor deposition densification treatment, the smoothness of the polished surface of the dynamic sealing ring is improved, thereby reducing the friction coefficient and improving the service life. The dynamic sealing ring is deposited and densified using a porous foam carbon matrix. The high open porosity and specific surface area accelerate the rate of chemical vapor deposition densification. The density can reach 1.85 g / cm³ in only 60 hours, improving the preparation efficiency.

[0021] Compared with the prior art, the beneficial effects of the present application are:

[0022] 1. The present application proposes a new preparation process for carbon dynamic sealing rings, which successfully prepares high-performance carbon dynamic sealing rings by combining porous foam carbon preforms with atmospheric chemical vapor deposition densification, ensuring that the products meet the requirements of high-temperature carbon dynamic sealing rings in terms of physical properties, mechanical properties, and friction properties.

[0023] 2. The chemical vapor deposition densification method used in the present application significantly reduces the number of micropores on the surface of the dynamic sealing ring, which helps to improve the smoothness of the polished surface, thereby reducing the friction coefficient and improving the service life.

[0024] 3、The advantage of the porous foam carbon matrix for depositing densification in the application lies in its ultra-high open porosity and specific surface area, which greatly speeds up the rate of chemical vapor deposition, in addition, the processability of the foam carbon matrix makes it can be processed into any required shape, providing stronger design flexibility.

[0025] 4、Compared with the hot isostatic pressing forming process, the atmospheric pressure chemical vapor deposition process equipment of the application is simpler, the preparation period is shorter, and there is no special requirement for the raw materials, which greatly reduces the cost of raw materials, therefore, the application not only has significant practicality and economic value, but also provides a new idea and method for the preparation of carbon dynamic sealing ring.

[0026] 5、In the carbonization process, the use of nitrogen atmosphere protection can effectively isolate oxygen and prevent the asphalt foam carbon template from being oxidized at high temperature, thereby improving the safety and reliability of the material.

[0027] The application provides a kind of carbon dynamic sealing ring preparation process, which is simple and economical, and the service life of the material is improved, and the problems of long preparation period, high cost, short service life and unstable quality of existing materials are effectively overcome. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the scheme in the application, the drawings needed in the description of the embodiments of the application will be briefly introduced below, and obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0029] Figure 1 is the process flow diagram provided by the application. DETAILED DESCRIPTION

[0030] The preferred embodiments of the application will be described in detail below with reference to the drawings, so that the advantages and features of the application can be more easily understood by those skilled in the art, and the scope of protection of the application can be more clearly defined. Obviously, the described embodiments are only a part of the embodiments of the application, not all the embodiments. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0031] The terms "comprise", "comprising", "include", "including", "have" and "having" and any variations thereof in the Specification and in the claims of the application and in the above description shall not be construed as excluding any additional component, feature, step, or aspect.

[0032] Referring to Figure 1 A preparation method of a carbon dynamic sealing ring, comprising the following steps:

[0033] Step one, crushing the mesophase pitch, then putting the crushed pitch into a mold, and then putting the mold into a foaming reaction device for foaming treatment, and after the foaming is completed, cooling to room temperature to obtain a pitch-based foam carbon precursor;

[0034] Step two, carbonizing the obtained pitch-based foam carbon precursor in a high-temperature carbonization furnace under nitrogen atmosphere protection for 4-6 hours, to obtain a pitch foam carbon template;

[0035] Step three, cutting the pitch foam carbon template according to the required size of the dynamic sealing ring to obtain a preform for deposition, and then performing surface activation treatment on the preform;

[0036] Step four, performing chemical vapor deposition densification treatment on the foam carbon preform subjected to surface activation treatment in a deposition furnace;

[0037] Step five, machining the deposition-densified raw blank according to the required size of the dynamic sealing ring to obtain a ring-shaped carbon dynamic sealing ring with uniform texture.

[0038] In step three, the surface activation treatment is specifically performed as follows: soaking the preform in deionized water, then ultrasonic cleaning to remove dust in the pores of the preform, then soaking the cleaned preform in a nitric acid solution, heating the solution to 60-80 DEG C and keeping for 1-3 hours, and finally cleaning and drying the preform with deionized water for use.

[0039] In step one, the foaming treatment is specifically performed as follows: first, increasing the temperature to 230-270 DEG C at a temperature increasing rate of 3-8 DEG C / min, then increasing the pressure in the kettle to 2.8-3.3 MPa by introducing nitrogen, then increasing the temperature to 430-460 DEG C at a temperature increasing rate of 1-3 DEG C / min, and keeping the temperature for 3-5 hours.

[0040] Step one, the porous carbon foam precursor, in addition to using mesophase pitch foaming, also can use high melting point pitch, phenolic resin and other polymer compounds foaming; Step three, the foam carbon surface activation treatment, in addition to using nitric acid oxidation treatment, also can use sulfuric acid, hydrogen peroxide and other oxidants treatment; Step four, the chemical vapor deposition densification, in addition to using natural gas as carbon source gas, also can use propylene, propane and other carbon source gas.

[0041] As the improvement of the above technical scheme, in the preparation process of pitch-based foam carbon precursor, the pitch is crushed to 80-120 mesh before foaming to improve the foaming effect and uniformity of pitch, the pitch crushing process adopts mechanical crushing or ultrasonic crushing technology, and the foaming reaction device is an autoclave to ensure that the pitch can fully foam under high temperature and high pressure conditions, the inner wall of the autoclave is made of corrosion-resistant material to improve the service life and safety of the equipment, such as special ceramics or alloy to prolong the service life of the furnace body, and the autoclave adopts multi-layer insulation to reduce external heat loss and protect the operator from high temperature.

[0042] As the improvement of the above technical scheme, in the carbonization process of pitch foam carbon template, the carbonization temperature is 900-1100℃ to ensure the carbonization effect and quality of pitch foam carbon template, the high-temperature carbonization furnace adopts a program-controlled temperature system for temperature control to accurately control the carbonization temperature and time, in the surface activation process of foam carbon preform, the ultrasonic cleaning time is 15-30 minutes to ensure that the dust in the preform holes is effectively removed, the ultrasonic cleaning equipment uses a frequency-adjustable ultrasonic generator to adapt to preforms of different pore sizes, and the concentration of nitric acid solution is 35%-70% to ensure the activation effect of the preform surface, and the nitric acid solution is heated by a circulating heating system to maintain the uniformity of the solution temperature.

[0043] As the improvement of the above technical scheme, in the chemical vapor deposition densification process, the deposition temperature is 1500-1700℃ under normal pressure or slightly positive pressure to ensure the densification effect and quality of the foam carbon preform, the deposition furnace adopts multi-zone temperature control technology to realize temperature gradient control during the deposition process, the ratio of carbon source gas to carrier gas is V 碳源气 :V 载气 =0.1-0.15:1 to ensure the uniformity and efficiency of the deposition densification, the carbon source gas and carrier gas are controlled by an accurate flow control system to ensure the accuracy of the gas ratio, and in the chemical vapor deposition densification process, the deposition time is 50-80 hours to ensure that the density of the foam carbon preform reaches 1.85g / cm³, and the deposition time is monitored and adjusted by a control system to improve the deposition efficiency and product quality.

[0044] As an improvement of the above technical solution, the process further includes an environmental monitoring step, a quality control step and a data recording and analysis step. The quality control step involves quality detection of intermediate products after each preparation stage to ensure the quality and performance of the final product. The environmental monitoring step involves real-time monitoring and control of environmental conditions such as humidity and temperature during the preparation process to ensure the stability of the preparation process and the consistency of the product. The data recording and analysis step involves recording all parameters and conditions during the preparation process and using data analysis techniques to optimize the preparation process, improve efficiency and product quality, including data collection, data preprocessing and data analysis. First, all parameter and condition data related to the preparation process need to be collected. After collecting the raw data, data processing and sorting are performed to eliminate outliers, missing values and duplicate data to ensure data quality and accuracy. Statistical analysis, machine learning and other methods are used to analyze the data in depth, extract useful patterns and trends from the cleaned data, and predict future behavior through mathematical models.

[0045] As an improvement of the above technical solution, in step two, a high-temperature carbonization furnace under nitrogen atmosphere protection is used for carbonization. Nitrogen atmosphere protection can effectively isolate oxygen to prevent the pitch foam carbon template from being oxidized at high temperature, resulting in a decrease in material performance. The system is equipped with a nitrogen purity monitoring device to ensure that the nitrogen entering the carbonization furnace has a purity of more than 99.99% to minimize the risk of oxidation. The carbonization furnace is equipped with a gas pressure regulation system, which includes a gas pressure sensor and an electric valve, to accurately control the pressure in the furnace during the carbonization process, ensuring uniform distribution of the nitrogen atmosphere and stable operation of the carbonization furnace. The gas pressure sensor inside the carbonization furnace can accurately measure the pressure changes during the carbonization process, ensuring the accuracy of pressure control. Users can set safety limits for gas pressure. Once these limits are exceeded, the system will automatically take measures such as opening the electric valve to release gas and release pressure. At the same time, an integrated alarm system is provided to sound and light alarms when the gas pressure exceeds the preset range, reminding the operator to take appropriate measures.

[0046] As an improvement of the above technical solution, a carbon dynamic sealing ring is obtained by the above preparation method, and the dynamic sealing ring has the following characteristics: the bulk density reaches 1.85 g / cm3, the surface open porosity is less than 0.1%, the compressive strength is greater than 360 MPa, and the friction coefficient is less than 0.1, which meets the performance requirements of high-temperature carbon dynamic sealing ring. In the preparation process of the dynamic sealing ring, the foaming conditions and carbonization conditions of the pitch-based foam carbon precursor are controlled to realize the microstructure control of the dynamic sealing ring. Through chemical vapor deposition densification treatment, the number of micropores on the surface of the dynamic sealing ring is significantly reduced, the smoothness of the polished dynamic sealing ring surface is improved, and the friction coefficient is reduced, thereby improving the service life. The dynamic sealing ring adopts porous foam carbon matrix for deposition densification, and the super-high open porosity and specific surface area accelerate the rate of chemical vapor deposition densification, and the density can reach 1.85 g / cm3 only in 60 hours, thereby improving the preparation efficiency.

[0047] The working principle and use method of the present application are as follows:

[0048] Working principle:

[0049] Preparation of pitch-based foam carbon precursor: The mesophase pitch is broken to 80-120 mesh by mechanical breaking or ultrasonic breaking technology to improve the foaming effect and uniformity. The broken pitch is placed in a mold, and then the mold is placed in an autoclave for foaming treatment. During the foaming process, first, the temperature is raised to 230-270 DEG C at a rate of 3-8 DEG C / min, then nitrogen is introduced to raise the pressure in the autoclave to 2.8-3.3 MPa, and then the temperature is raised to 430-460 DEG C at a rate of 1-3 DEG C / min. After holding for 3-5 hours, it is cooled to room temperature to obtain a pitch-based foam carbon precursor.

[0050] Carbonization process: The pitch-based foam carbon precursor is carbonized in a high-temperature carbonization furnace under nitrogen atmosphere protection, the carbonization temperature is 900-1100 DEG C, and the constant temperature is 4-6 hours, and the pitch foam carbon template is obtained.

[0051] Surface activation treatment: The pitch foam carbon template is cut according to the size of the required dynamic sealing ring to obtain a preform for deposition, and the preform is subjected to surface activation treatment, including soaking in deionized water, ultrasonic cleaning for 15-30 minutes to remove dust, then soaking in 35%-70% nitric acid solution, heating to 60-80 DEG C for 1-3 hours, and finally washing with deionized water and drying for use.

[0052] Chemical vapor deposition densification treatment: The foam carbon preform subjected to surface activation treatment is subjected to chemical vapor deposition densification treatment in a deposition furnace, the deposition temperature is 1500-1700 DEG C, natural gas is used as carbon source gas, argon-hydrogen mixed gas is used as carrier gas, Vcarbon source gas: Vcarrier gas=0.1-0.15, and the deposition time is 50-80 hours.

[0053] Mechanical Processing: The as-deposited green compact is machined to the desired size of the dynamic seal ring, resulting in a uniform ring-shaped carbon dynamic seal ring.

[0054] Method of Use:

[0055] Preparation of Raw Materials: Prepare mesophase pitch and break it into appropriate particle size as needed.

[0056] Foaming Process: Place the broken pitch into a mold and perform foaming in an autoclave, strictly following the temperature and pressure conditions mentioned above.

[0057] Carbonization: Perform carbonization under nitrogen protection, controlling the carbonization temperature and time to ensure the quality of the pitch foam carbon template.

[0058] Cutting and Activation Process: Cut the carbon template into appropriate size according to the desired dynamic seal ring size and perform surface activation treatment, including cleaning and chemical treatment.

[0059] Chemical Vapor Deposition: Perform chemical vapor deposition densification treatment in a deposition furnace, controlling the deposition temperature, gas ratio, and deposition time.

[0060] Mechanical Processing and Quality Inspection: Perform mechanical processing on the as-deposited green compact to produce the final carbon dynamic seal ring, and conduct quality inspection on the intermediate products after each preparation stage to ensure the performance and quality of the final product.

[0061] Environmental Monitoring and Data Recording: Monitor and control environmental conditions in real time during the entire preparation process, record all parameters and conditions, and use data analysis techniques to optimize the preparation process.

[0062] Example

[0063] Objective: To prepare a batch of carbon dynamic seal rings with long service life for sealing positions in aerospace engines.

[0064] Preparation of Raw Materials and Equipment:

[0065] Mesophase Pitch: As the main raw material, select mesophase pitch suitable for high-temperature applications.

[0066] This pitch needs to have a higher aromaticity and appropriate H / C atomic ratio to ensure its good conversion during the preparation process.

[0067] Deionized Water: Used for cleaning the preform to ensure no impurities.

[0068] The resistivity of deionized water should be greater than 0.5 MΩ·cm, up to 18 mega, to ensure its purity higher than distilled water, suitable for cleaning the preform to prevent impurity contamination.

[0069] Nitric acid: Concentration of 50% for surface activation treatment of the preform.

[0070] Select nitric acid of grade GR (Good Regular) or AR (Analytical Regular) with purity of 99.8% and 99.7% respectively to ensure the effectiveness of the surface activation treatment.

[0071] Natural gas, argon, hydrogen: As carbon source gas and carrier gas for chemical vapor deposition.

[0072] Autoclave: Used for foaming treatment of pitch, with special ceramic material on the inner wall and multi-layer insulation.

[0073] High-temperature carbonization furnace: Equipped with a program-controlled temperature system for carbonization of pitch-based foam carbon precursor.

[0074] Ultrasonic cleaner: Adjustable frequency, used for surface cleaning of the preform.

[0075] Deposition furnace: Equipped with multi-zone temperature control technology for chemical vapor deposition densification treatment.

[0076] Numerical control machine tool: Used for final machining to ensure dimensional accuracy.

[0077] Nitrogen purity monitoring device, gas pressure regulating system, gas pressure sensor: Used to ensure the nitrogen atmosphere during carbonization.

[0078] Detailed steps:

[0079] Preparation of pitch-based foam carbon precursor:

[0080] Crush mesophase pitch to 100 mesh using mechanical crushing technology, then put the crushed pitch into a mold, and then put the mold into an autoclave. Increase the temperature to 250°C at a rate of 5°C / min, increase the pressure in the autoclave to 3.0 MPa by introducing nitrogen, increase the temperature to 450°C at a rate of 2°C / min, and keep the temperature for 4 hours, then cool to room temperature to obtain the pitch-based foam carbon precursor.

[0081] Use mechanical crushing technology to crush mesophase pitch to 100 mesh to improve foaming effect and uniformity. During the crushing process, pay attention to the safety of surrounding facilities and pipelines, and ensure that the crushed pitch does not pollute the surrounding environment.

[0082] Carbonization process:

[0083] Carbonize the pitch-based foam carbon precursor in a high-temperature carbonization furnace under nitrogen atmosphere protection, carbonization temperature is 1000°C, constant temperature for 6 hours, use nitrogen purity monitoring device to ensure nitrogen purity reaches 99.99%, use gas pressure regulating system and gas pressure sensor to accurately control the pressure in the furnace.

[0084] Cutting and surface activation treatment:

[0085] According to the size of the dynamic sealing ring required, the pitch foam carbon template is cut into a preform for deposition, the preform is soaked in deionized water, then ultrasonic cleaning is performed for 20 minutes to remove dust in the holes, the cleaned preform is soaked in a 50% nitric acid solution, heated to 70°C for 2 hours, and finally the preform is cleaned with deionized water and dried for use.

[0086] Chemical vapor deposition densification treatment:

[0087] The surface-activated foam carbon preform is subjected to chemical vapor deposition densification treatment in a deposition furnace, with a deposition temperature of 1600°C, natural gas as the carbon source gas, argon-hydrogen mixed gas as the carrier gas, Vcarbon source gas:Vcarrier gas = 0.12, a deposition time of 70 hours, and a precise flow control system is used to ensure the accuracy of the gas ratio, and the control system monitors and adjusts the deposition time.

[0088] Mechanical processing:

[0089] The deposited and densified raw blank is mechanically processed according to the size of the dynamic sealing ring required, using a numerical control machine tool, to obtain a ring-shaped carbon dynamic sealing ring with uniform texture.

[0090] Quality detection and environmental monitoring:

[0091] Quality detection is performed on the intermediate products after each preparation stage, including the determination of bulk density, surface open porosity, compressive strength and friction coefficient, real-time monitoring and control of environmental conditions such as humidity and temperature, and recording of all parameters and conditions, and data analysis techniques are used to optimize the preparation process.

[0092] Results analysis:

[0093] Through the above steps, a batch of carbon dynamic sealing rings are successfully prepared, with a bulk density of 1.85 g / cm³, a surface open porosity of less than 0.1%, a compressive strength of more than 360 MPa, and a friction coefficient of less than 0.1, meeting the performance requirements of high-temperature carbon dynamic sealing rings. In addition, by controlling the foaming conditions and carbonization conditions of the pitch-based foam carbon precursor, the microstructure of the dynamic sealing ring is controlled, and through chemical vapor deposition densification treatment, the number of micro-pores on the surface of the dynamic sealing ring is significantly reduced, the smoothness of the polished dynamic sealing ring surface is improved, thereby reducing the friction coefficient and improving the service life. The entire process embodies the characteristics of simple operation, economy and excellent performance, and has great practicality and economic value.

[0094] The above merely aims to illustrate the technical solutions of the present application, but not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, those ordinarily skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced equivalently; any equivalent structure or equivalent flow conversion made by using the content of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing a carbon dynamic sealing ring, characterized in that, It comprises the following steps: Step one, crushing the mesophase pitch, then putting the crushed pitch into a mold, and then putting the mold into a foaming reaction device for foaming treatment, and after the foaming is completed, cooling to room temperature to obtain a pitch-based foam carbon precursor; the foaming treatment is specifically as follows: First, increase the temperature to 230-270℃ at a rate of 3-8℃ / min, then increase the pressure in the foaming reaction device to 2.8-3.3MPa by introducing nitrogen, and then increase the temperature to 430-460℃ at a rate of 1-3℃ / min, and keep the temperature for 3-5 hours; Step two, carbonizing the obtained pitch-based foam carbon precursor in a high-temperature carbonization furnace under the protection of nitrogen atmosphere, keeping the temperature constant for 4-6 hours to obtain a pitch foam carbon template; during the carbonization process of the pitch-based foam carbon precursor, the carbonization temperature is 900-1100℃, and the high-temperature carbonization furnace uses a program-controlled temperature system for temperature control; Step three, cutting the pitch foam carbon template according to the size of the required dynamic sealing ring to obtain a preform for deposition, and then performing surface activation treatment on the preform; the surface activation treatment is specifically as follows: Soak the preform in deionized water, then ultrasonically clean it to remove dust in the pores of the preform, then soak the cleaned preform in a nitric acid solution, heat the solution to 60-80℃ and keep it for 1-3 hours, and finally clean and dry the preform with deionized water for use; During the surface activation treatment of the preform, the ultrasonic cleaning time is 15-30 minutes, the ultrasonic cleaning equipment uses a frequency-adjustable ultrasonic generator, the concentration of the nitric acid solution is 35%-70%, and the nitric acid solution is heated using a circulating heating system; Step four, performing chemical vapor deposition densification treatment on the preform subjected to surface activation treatment in a deposition furnace, using natural gas as the carbon source gas and argon-hydrogen mixed gas as the carrier gas; The chemical vapor deposition densification process is carried out at a deposition temperature of 1500-1700 DEG C under normal pressure or slightly positive pressure, the deposition furnace adopts multi-zone temperature control technology, the ratio of the carbon source gas to the carrier gas is V 碳源气 :V 载气 =0.1-0.15:1, the carbon source gas and the carrier gas adopt a precise flow control system for gas flow control, the chemical vapor deposition densification process is carried out for a deposition time of 50-80 hours, and the deposition time is monitored and adjusted by a control system. Step five, machining the deposition-densified raw blank according to the size of the required dynamic sealing ring to obtain a ring-shaped carbon dynamic sealing ring with uniform texture.

2. The method of claim 1, wherein, During the preparation of the pitch-based foam carbon precursor in step one, the pitch is crushed to 80-120 mesh before foaming, the pitch crushing process uses mechanical crushing or ultrasonic crushing technology, the foaming reaction device is a high-pressure kettle, the inner wall of the high-pressure kettle is made of corrosion-resistant material, the high-pressure kettle is provided with a multi-layer heat insulation structure, and the high-pressure kettle is provided with a gas pressure regulating system including a gas pressure sensor and an electric valve.

3. The method of claim 1, wherein, The program-controlled temperature system in step two is provided with a nitrogen purity monitoring device.

4. The method of claim 1, wherein, The method also includes an environment monitoring step, a quality control step and a data record analysis step, the quality control step involves quality detection of intermediate products after each preparation stage, the environment monitoring step involves real-time monitoring and control of environmental conditions during the preparation process, the data record analysis step involves recording all parameters and conditions during the preparation process, and using data analysis techniques to optimize the preparation process, including data collection, data preprocessing and data analysis, first, all parameter and condition data related to the preparation process need to be collected, after collecting the original data, data processing and arrangement are carried out to eliminate abnormal values, missing values and repeated data, ensure the quality and accuracy of the data, use statistical analysis and machine learning methods to deeply analyze the data, extract useful patterns and trends from the cleaned data, and predict future behavior through mathematical models.

5. A carbon dynamic seal ring, characterized by, The dynamic sealing ring is obtained by the preparation method of any one of claims 1-4, and has the following properties: the bulk density reaches 1.85 g / cm3, the surface open porosity is less than 0.1%, the compressive strength is greater than 360 MPa, and the friction coefficient is less than 0.1.

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