A kind of carbon fiber hard felt with coating and preparation method thereof

Abstract

The present invention provides a carbon fiber hard felt with a coating and a preparation method thereof; the preparation method comprises the following steps: a) subjecting carbon fiber precursors to sequential short-cutting, combing, pulling, and needle-punching to obtain a soft felt; then applying a curing resin to the felt to obtain a soft felt coated with a coating; b) drying the soft felt coated with the coating obtained in step a) to remove moisture, and then curing the resin to obtain a cured felt body; c) subjecting the cured felt body obtained in step b) to sequential carbonization treatment, graphitization treatment, and surface cleaning, and then spraying a coating material to form a coating, and after the coating is cured, performing a purification treatment to obtain a carbon fiber hard felt with a coating. The preparation method can distinguish whether a hard felt product can be obtained as a finished product in the previous process, and can distinguish qualified and unqualified products at high temperature in the carbonization process. It has low requirements for subsequent manual brushing and high-temperature equipment, low manufacturing cost, short time, easy purification, and can ensure that the impurity content is easily reduced to below 5ppm.

Description

Technical Field

[0001] The present invention relates to the technical field of coated hard felt, and more particularly to a carbon fiber hard felt with a coating and a preparation method thereof. Background Art

[0002] Coated hard felt is primarily used in the semiconductor industry, where it must be used in thermal environments such as SiC epitaxial furnaces to combat silicon vapor corrosion. Currently, conventional coated hard felts suffer from issues such as short lifespan, high cost, and high levels of impurities when used in environments subject to silicon vapor corrosion.

[0003] Chinese patent publication number CN116837642A discloses a hard felt coating and a preparation method thereof, as well as a carbon fiber hard felt and a preparation method thereof. The main changes are made in the coating, using two brushings and two depositions to change the surface hardness and smoothness of the hard felt. The steps are to brush the first solution, deposit once, brush the second solution, and then deposit once. The final result is a product that can be repeated 4000 times and 8000 times in 12 hours at 2000°C and is resistant to ethanol and alkali corrosion.

[0004] However, the above-mentioned existing technology has a complicated operation method and has high requirements for people, machines, materials and methods, which may lead to low yield. Any error in each painting link will lead to product scrapping, and the overall cost is high. It is not suitable for environments with silicon vapor corrosion and is not suitable for the semiconductor industry. In addition, other ordinary coatings use graphite as the coating material, and it is difficult to purify the graphite coating felt as a whole. The impurity content is difficult to reach below 5ppm (the metal content is below 5 parts per million), and problems such as powder falling off will occur during subsequent use, polluting the thermal environment and causing adverse effects. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a carbon fiber hard felt with a coating and a preparation method thereof. The preparation method provided by the present invention can distinguish whether the hard felt product can be obtained as a finished product in the previous process, and can distinguish qualified and unqualified products at high temperature in the carbonization treatment process. Unqualified products can be reprocessed and remade, which reduces the waste of raw materials. It also has low requirements for subsequent manual brushing, does not have too many variables, does not require high-temperature equipment, has low manufacturing cost, short time, easy purification, and ensures that the impurity content can easily reach below 5ppm.

[0006] The present invention provides a method for preparing a carbon fiber rigid felt with a coating, comprising the following steps:

[0007] a) chopping, combing, drawing and needle punching the carbon fiber precursor in sequence to obtain a soft felt; then coating the raw fiber with a curing resin to obtain a soft felt coated with a resin;

[0008] b) drying the soft felt coated with glue obtained in step a) and curing the glue to obtain a cured felt body;

[0009] c) The solidified felt obtained in step b) is sequentially subjected to carbonization treatment, graphitization treatment, and surface cleaning, and then sprayed with a coating material to form a coating. After the coating is solidified, it is purified to obtain a coated carbon fiber hard felt.

[0010] Preferably, the chopped length in step a) is 40 mm to 60 mm; the pulling arranges 95% to 100% of the carbon filaments in the same direction; and the soft felt obtained by the needle punching and compounding has a thickness of 5 mm to 10 mm.

[0011] Preferably, the curing resin in step a) is a mixed resin material of one or more of polycarbosilane, dimethylsilane, methyltriethoxysilane and phenolic resin.

[0012] Preferably, the temperature for drying the moisture in step b) is 40° C. to 70° C., and the time is 0.5 h to 2 h.

[0013] Preferably, the glue curing pressure in step b) is 0.1 MPa to 0.5 MPa, the temperature is 130° C. to 165° C., and the time is 3 h to 6 h.

[0014] Preferably, the carbonization process in step c) is specifically as follows:

[0015] The heating time from rt to 200℃ is 100min~200min, the heating time from 200℃ to 500℃ is 150min~200min, the heating time from 500℃ to 800℃ is 200min~350min, and the heat preservation time at 800℃ is 6h~9h;

[0016] or,

[0017] The heating time from rt to 250℃ is 150min~220min, the heating time from 250℃ to 600℃ is 200min~310min, the heating time from 600℃ to 800℃ is 80min~160min, and the heat preservation time at 800℃ is 6h~9h;

[0018] or,

[0019] The heating time from rt to 200℃ is 150min~240min, the heating time from 200℃ to 400℃ is 90min~150min, the heating time from 400℃ to 800℃ is 200min~280min, and the insulation time at 800℃ is 6h~9h.

[0020] Preferably, the graphitization process in step c) is specifically as follows:

[0021] The carbonized felt is placed in a graphitization furnace and counterweighted with graphite plates 1 to 3 times larger than its own weight. The graphitization temperature is 1800°C to 2400°C and the time is 4 to 8 hours.

[0022] Preferably, the coating material in step c) is:

[0023] 1wt% to 3wt% thickener, 8wt% to 20wt% powdered phenolic resin, 15wt% to 25wt% phenyltrimethoxysilane, 50wt% to 70wt% pure water, 5wt% to 10wt% carbon powder;

[0024] or,

[0025] 0.5wt% to 2wt% thickener, 10wt% to 25wt% powdered phenolic resin, 10wt% to 20wt% polymethylsilane, 50wt% to 70wt% pure water, 5wt% to 10wt% carbon powder;

[0026] or,

[0027] 1wt% to 3wt% thickener, 10wt% to 25wt% powdered phenolic resin, 10wt% to 25wt% polydimethylsiloxane, 50wt% to 70wt% pure water, 5wt% to 10wt% carbon powder, and 4wt% to 8wt% silane coupling agent;

[0028] The coating formed by spraying has a thickness of 0.5 mm to 1 mm.

[0029] Preferably, the coating is cured at a temperature of 140° C. to 200° C. for 2 hours to 5 hours in step c).

[0030] The temperature of the purification treatment is 2000°C to 2400°C.

[0031] The present invention also provides a carbon fiber hard felt with a coating, which is prepared by the preparation method described in the above technical solution.

[0032] The present invention provides a coated carbon fiber hard felt and a preparation method thereof. The preparation method comprises the following steps: a) subjecting carbon fiber precursors to sequential chopping, carding, drawing, and needle punching to obtain a soft felt; then applying a curing resin to the felt to obtain a coated soft felt; b) drying the coated soft felt obtained in step a) to remove moisture and curing the resin to obtain a cured felt body; c) subjecting the cured felt body obtained in step b) to sequential carbonization, graphitization, and surface cleaning, spraying a coating material to form a coating, and performing a purification treatment after the coating is cured to obtain a coated carbon fiber hard felt. Compared with the prior art, the preparation method provided by the present invention utilizes specific process steps to achieve better overall interaction: whether the hard felt product can be obtained can be determined in the previous process, and qualified and unqualified products can be separated at high temperature in the carbonization process. Unqualified products can be reprocessed, reducing the waste of raw materials, requiring less manual brushing, eliminating too many variables, and requiring less high-temperature equipment. The manufacturing cost is low, the time is short, the purification is easy, and the impurity content can be easily reduced to below 5ppm. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] The present invention provides a method for preparing a carbon fiber rigid felt with a coating, comprising the following steps:

[0035] a) chopping, combing, drawing and needle punching the carbon fiber precursor in sequence to obtain a soft felt; then coating the raw fiber with a curing resin to obtain a soft felt coated with a resin;

[0036] b) drying the soft felt coated with glue obtained in step a) and curing the glue to obtain a cured felt body;

[0037] c) The solidified felt obtained in step b) is sequentially subjected to carbonization treatment, graphitization treatment, and surface cleaning, and then sprayed with a coating material to form a coating. After the coating is solidified, it is purified to obtain a coated carbon fiber hard felt.

[0038] The invention firstly subjects carbon fiber precursors to short cutting, carding, pulling and needle punching in sequence to obtain soft felt; and then uses curing resin for glue coating to obtain glue-coated soft felt.

[0039] The present invention has no particular limitation on the source of the carbon fiber precursor, and commercially available products known to those skilled in the art may be used.

[0040] In the present invention, the short-cutting process is performed by using a short-cutting machine well known to those skilled in the art; the cutting length of the short-cutting is preferably 40 mm to 60 mm, more preferably 50 mm, to obtain short-cut shreds.

[0041] In the present invention, the combing process uses a carding machine familiar to those skilled in the art to comb into a mesh; then through a specific direction pulling device, 95% to 100% of the carbon filaments are preferably arranged in the same direction; the present invention uses filaments arranged in the same direction to reduce the generation of broken filaments in subsequent machining, and reduces the problem of surface spraying due to broken filaments during coating.

[0042] In the present invention, the thickness of the soft felt obtained by needle punching is preferably 5 mm to 10 mm.

[0043] In the present invention, the curing resin is preferably a mixed resin material of one or more of polycarbosilane, dimethylsilane, methyltriethoxysilane and phenolic resin, more preferably a mixed resin material of polycarbosilane and phenolic resin, or a mixed resin material of dimethylsilane and phenolic resin, or a mixed resin material of methyltriethoxysilane and phenolic resin; wherein the mass ratio of polycarbosilane to phenolic resin is 1:5; the mass ratio of dimethylsilane to phenolic resin is 1:3; the mass ratio of methyltriethoxysilane to phenolic resin is 1:2.

[0044] In the present invention, the solidified resin is obtained by mixing the raw materials and then stirring; the stirring speed is preferably 3000r / min to 5000r / min, and the time is preferably 5min to 20min; after stirring evenly, the solidified resin is placed in an automated spraying equipment, and the front and back surfaces of the soft felt are evenly sprayed to complete the gluing process.

[0045] The present invention adopts a mixed resin material with the above-mentioned specific components and specific proportions, which can enable the interlayer bonding surface of the base felt to have the same silicon carbide material as the use environment after subsequent high-temperature treatment, reducing the adverse effects caused by the volatilization of impurities in the base, improving the reliability of the product during use, and increasing the life of the felt in a silicon vapor corrosion environment.

[0046] After obtaining the glue-coated soft felt, the present invention dries the obtained glue-coated soft felt to remove moisture, and then solidifies the glue to obtain a solidified felt body.

[0047] In the present invention, the process of drying the moisture is preferably carried out in a constant temperature oven well known to those skilled in the art; the temperature for drying the moisture is preferably 40°C to 70°C, more preferably 60°C to 70°C, and the time is preferably 0.5h to 2h, more preferably 1h; the moisture is dried without causing the phenolic resin therein to achieve a gel effect.

[0048] Then, the present invention stacks the dried felt to a predetermined finished product thickness for glue curing; the glue curing pressure is preferably 0.1MPa to 0.5MPa, more preferably 0.2MPa, the temperature is preferably 130℃ to 165℃, more preferably 140℃, and the time is preferably 3h to 6h, more preferably 5h.

[0049] After obtaining the solidified felt body, the present invention sequentially carbonizes, graphitizes and cleans the surface of the solidified felt body, sprays the solidified felt body with a coating material to form a coating, and purifies the solidified coating to obtain a carbon fiber hard felt with a coating.

[0050] In the present invention, the carbonization process is preferably carried out in a vacuum high-temperature furnace well known to those skilled in the art; the carbonization process is preferably specifically as follows:

[0051] The heating time from rt to 200℃ is 100min~200min, the heating time from 200℃ to 500℃ is 150min~200min, the heating time from 500℃ to 800℃ is 200min~350min, and the heat preservation time at 800℃ is 6h~9h;

[0052] or,

[0053] The heating time from rt to 250℃ is 150min~220min, the heating time from 250℃ to 600℃ is 200min~310min, the heating time from 600℃ to 800℃ is 80min~160min, and the heat preservation time at 800℃ is 6h~9h;

[0054] or,

[0055] The heating time from rt to 200℃ is 150min~240min, the heating time from 200℃ to 400℃ is 90min~150min, the heating time from 400℃ to 800℃ is 200min~280min, and the insulation time at 800℃ is 6h~9h.

[0056] The reason for designing the above-mentioned specific heating curve in the present invention is that the optimal heating curve can make the resin mixture react more fully, ensure that it is less deformed by heat in subsequent use, reduce the risk of defective products, enhance reliability, extend service life, and also make the deformation of the felt body in the subsequent graphitization process less, increase the yield rate, and reduce costs.

[0057] In the present invention, the graphitization process is preferably carried out in a graphitization furnace well known to those skilled in the art; the graphitization process is preferably specifically as follows:

[0058] The carbonized felt is placed in a graphitization furnace and a graphite plate 1 to 3 times larger than its own weight is used to balance it. The graphitization temperature is 1800 to 2400 degrees Celsius and the time is 4 to 8 hours.

[0059] More preferably:

[0060] The carbonized felt was placed in a graphitization furnace and counterweighted with a graphite plate twice its own weight. The graphitization temperature was 1850°C and the time was 6 hours.

[0061] Afterwards, the present invention preferably processes the graphitized felt into a desired shape, and cleans the surface with sandpaper in preparation for coating.

[0062] In the present invention, the coating material is preferably:

[0063] 1wt% to 3wt% thickener, 8wt% to 20wt% powdered phenolic resin, 15wt% to 25wt% phenyltrimethoxysilane, 50wt% to 70wt% pure water, 5wt% to 10wt% carbon powder;

[0064] or,

[0065] 0.5wt% to 2wt% thickener, 10wt% to 25wt% powdered phenolic resin, 10wt% to 20wt% polymethylsilane, 50wt% to 70wt% pure water, 5wt% to 10wt% carbon powder;

[0066] or,

[0067] 1wt% to 3wt% thickener, 10wt% to 25wt% powdered phenolic resin, 10wt% to 25wt% polydimethylsiloxane, 50wt% to 70wt% pure water, 5wt% to 10wt% carbon powder, and 4wt% to 8wt% silane coupling agent.

[0068] The present invention has no particular limitation on the sources of the raw materials in the coating material, and commercially available products known to those skilled in the art may be used.

[0069] The present invention preferably uses one of the three coating material ratios mentioned above, stirs them evenly and then uses automatic spraying equipment to spray them on the surface of the felt body. The thickness of the coating formed by spraying is preferably 0.5mm to 1mm.

[0070] Afterwards, the sprayed felt body is placed in an oven for coating curing; the coating curing temperature is preferably 140° C. to 200° C., more preferably 145° C., and the curing time is preferably 2 h to 5 h, more preferably 3 h.

[0071] Finally, the present invention preferably places the coated and cured felt into a purification furnace without adding weights, and each one is placed individually on a graphite pad for purification treatment; the temperature of the purification treatment is preferably 2000°C to 2400°C, more preferably 2350°C.

[0072] The preparation method provided by the present invention adopts specific process steps to achieve better overall interaction: whether the hard felt product can be obtained as a finished product can be distinguished in the previous process, and qualified and unqualified products can be distinguished at high temperature in the carbonization treatment process. Unqualified products can be reprocessed and remade, which reduces the waste of raw materials, and has low requirements for subsequent manual brushing, does not exist too many variables, and does not require high-temperature equipment. The manufacturing cost is low, the time is short, the purification is easy, and the impurity content is easily guaranteed to be below 5ppm.

[0073] The present invention also provides a coated carbon fiber rigid felt, produced using the preparation method described in the above technical solution. The coated carbon fiber rigid felt provided by the present invention has excellent resistance to silicon vapor corrosion and a service life far longer than that of ordinary rigid felt. It also features low cost, low thermal conductivity, a simple and controllable manufacturing process, and the ability to achieve 100% mechanized processing.

[0074] The present invention provides a coated carbon fiber hard felt and a preparation method thereof. The preparation method comprises the following steps: a) subjecting carbon fiber precursors to sequential chopping, carding, drawing, and needle punching to obtain a soft felt; then applying a curing resin to the felt to obtain a coated soft felt; b) drying the coated soft felt obtained in step a) to remove moisture and curing the resin to obtain a cured felt body; c) subjecting the cured felt body obtained in step b) to sequential carbonization, graphitization, and surface cleaning, spraying a coating material to form a coating, and performing a purification treatment after the coating is cured to obtain a coated carbon fiber hard felt. Compared with the prior art, the preparation method provided by the present invention utilizes specific process steps to achieve better overall interaction: whether the hard felt product can be obtained can be determined in the previous process, and qualified and unqualified products can be separated at high temperature in the carbonization process. Unqualified products can be reprocessed, reducing the waste of raw materials, requiring less manual brushing, eliminating too many variables, and requiring less high-temperature equipment. The manufacturing cost is low, the time is short, the purification is easy, and the impurity content can be easily reduced to below 5ppm.

[0075] In order to further illustrate the present invention, the following examples are provided for detailed description. The raw materials used in the following examples of the present invention are all commercially available.

[0076] Example 1

[0077] ① The carbon fiber raw yarn is cut into 40mm long short strands by a chopped machine, and then combed into a mesh by a carding machine. The combed mesh passes through a specific directional pulling device to arrange 98% of the carbon fibers in the same direction, and then is compounded into a soft felt with a thickness of 5mm by needle punching; then it is placed in a glue spraying machine and the front and back are evenly sprayed with the specified curing resin, which is a mixed resin material of methyltriethoxysilane and phenolic resin in a mass ratio of 1:2 (the mixed resin material is mixed evenly by stirring and then placed in the automatic spraying equipment, using a stirring speed of 4000r / min and stirring for 10min).

[0078] ② The evenly sprayed soft felt is dried in a constant temperature oven at 70°C for 0.5 hours to remove moisture without causing the phenolic resin therein to gel. The dried felt is stacked to the predetermined finished product thickness, and a pressure of 0.2 MPa is applied and the temperature is raised to 130°C for a constant temperature of 3 hours to obtain the cured product.

[0079] ③ Place the cured felt body into a vacuum high-temperature furnace for carbonization treatment. The carbonization process formulated according to the characteristics of the resin mixture is: rt-200℃ heating time is 100min, 200℃-500℃ heating time is 150min, 500℃-800℃ heating time is 200min, and 800℃ insulation time is 6h.

[0080] ④ Place the carbonized felt into a graphitization furnace and use a graphite plate that is 1 times heavier than its own weight to balance it. The graphitization temperature is 1800°C and the time is 6 hours.

[0081] ⑤ Process the graphitized felt into the required style and clean the surface with sandpaper in preparation for coating.

[0082] ⑥ Coating step: The coating material is: 1wt% thickener, 19wt% powdered phenolic resin, 15wt% phenyltrimethoxysilane, 60wt% pure water, and 5wt% carbon powder; after stirring evenly, use automatic spraying equipment to spray on the surface of the felt, and control the coating thickness to 0.5mm; put the sprayed felt into an oven and bake it at 140℃ for 2 hours to solidify it.

[0083] ⑦ Place the coated and cured felt into a purification furnace without adding weights. Each felt is placed individually on a graphite pad for purification at a purification temperature of 2300°C to obtain a coated carbon fiber hard felt.

[0084] Example 2

[0085] ① The carbon fiber raw yarn is cut into 50mm long short strands by a short cutter, and then carded into a mesh by a carding machine. The carded mesh passes through a specific directional pulling device to arrange 98% of the carbon fibers in the same direction, and then is compounded into a soft felt with a thickness of 5mm by needle punching; then it is placed in a glue spraying machine and the front and back are evenly sprayed with the specified curing resin, which is a mixed resin material of dimethyl silane and phenolic resin with a mass ratio of 1:3 (the mixed resin material is mixed evenly by stirring and then placed in the automatic spraying equipment, with a stirring speed of 4000r / min and stirring for 10min).

[0086] ② The evenly sprayed soft felt is dried in a constant temperature oven at 60°C for 1 hour to remove moisture without causing the phenolic resin therein to gel. The dried felt is stacked to the predetermined finished product thickness, and a pressure of 0.2 MPa is applied and the temperature is raised to 140°C for a constant temperature of 5 hours to obtain the cured product.

[0087] ③ Place the cured felt body into a vacuum high-temperature furnace for carbonization treatment. The carbonization process formulated according to the characteristics of the resin mixture is: rt-250℃ heating time is 160min, 250℃-600℃ heating time is 240min, 600℃-800℃ heating time is 120min, and 800℃ insulation time is 8h.

[0088] ④ Place the carbonized felt into a graphitization furnace and use a graphite plate twice its weight to balance it. The graphitization temperature is 1850°C and the time is 6 hours.

[0089] ⑤ Process the graphitized felt into the required style and clean the surface with sandpaper in preparation for coating.

[0090] ⑥ Coating step: The coating material is: 1wt% thickener, 15wt% powdered phenolic resin, 18wt% polymethylsilane, 60wt% pure water, and 6wt% carbon powder; after stirring evenly, use automatic spraying equipment to spray on the surface of the felt, and control the coating thickness to 1mm; put the sprayed felt into an oven and bake it at 145℃ for 3 hours to solidify it.

[0091] ⑦ Place the coated and cured felt into a purification furnace without adding weights. Each felt is placed individually on a graphite pad for purification at a purification temperature of 2350°C to obtain a coated carbon fiber hard felt.

[0092] Example 3

[0093] ① The carbon fiber raw yarn is cut into 60mm long short strands by a chopped machine, and then combed into a mesh by a carding machine. The combed mesh passes through a specific directional pulling device to arrange 98% of the carbon fibers in the same direction, and then is compounded into a soft felt with a thickness of 10mm by needle punching; then it is placed in a glue spraying machine and the front and back are evenly sprayed with the specified curing resin, which is a mixed resin material of polycarbosilane and phenolic resin with a mass ratio of 1:5 (the mixed resin material is mixed evenly by stirring and then placed in the automatic spraying equipment, using a stirring speed of 4000r / min and stirring for 15min).

[0094] ② The evenly sprayed soft felt is dried in a constant temperature oven at 70°C for 2 hours to remove moisture without causing the phenolic resin therein to gel. The dried felt is stacked to the predetermined finished product thickness, and a pressure of 0.2 MPa is applied and the temperature is raised to 165°C for a constant temperature of 6 hours to obtain the cured product.

[0095] ③ Place the cured felt body into a vacuum high-temperature furnace for carbonization treatment. The carbonization process formulated according to the characteristics of the resin mixture is: rt-200℃ heating time is 240min, 200℃-400℃ heating time is 150min, 400℃-800℃ heating time is 280min, and 800℃ insulation time is 9h.

[0096] ④ Place the carbonized felt into a graphitization furnace and use a graphite plate three times heavier than its own weight to balance it. The graphitization temperature is 2400°C and the time is 6 hours.

[0097] ⑤ Process the graphitized felt into the required style and clean the surface with sandpaper in preparation for coating.

[0098] ⑥ Coating step: The coating material is: 3wt% thickener, 20wt% powdered phenolic resin, 15wt% polydimethylsiloxane, 50wt% pure water, 5wt% carbon powder, and 7wt% silane coupling agent; after stirring evenly, use automatic spraying equipment to spray on the surface of the felt, and control the coating thickness to 1mm; put the sprayed felt into an oven and bake it at 200℃ for 5 hours to solidify it.

[0099] ⑦ Place the coated and cured felt into a purification furnace without adding weights. Each felt is placed individually on a graphite pad for purification at a purification temperature of 2400°C to obtain a coated carbon fiber hard felt.

[0100] Comparative Example 1

[0101] Ordinary carbon fiber cured felt (Yixianyi, CFC-3K).

[0102] The products provided in Examples 1 to 3 and Comparative Example 1 were placed in a simulated thermal field of silicon vapor corrosion, and the experimental data obtained are shown in the following table, along with the purity test results and thermal conductivity test results. The test method is:

[0103] The coated carbon fiber felt samples were treated at 1500°C for three days in a constant silicon vapor concentration, representing one complete process cycle. A second process cycle then commenced. The coated carbon fiber felt was deemed unusable when cracks appeared in the coating and / or 10% of the coating area fell off. The coating's service life was defined as the time when these first occurrences occurred.

[0104] Table 1 Experimental data table

[0105] Thermal conductivity test results / W / (m·K) Ash test results / ppm Service life / month Detection method YB / T 4130-2005 GDMS Same as above Example 1 0.198 3.76 10-11 Example 2 0.186 0.81 13-14 Example 3 0.210 5.42 12-13 Comparative Example 1 0.200 11.59 8-9

[0106] Experimental results show that the coated felt body purified by the preparation method provided by the present invention is resistant to silicon vapor erosion, has a service life much longer than ordinary hard felt, is low in cost, has low thermal conductivity, simple manufacturing process, controllable process, and can achieve 100% mechanized processing.

[0107] In summary, the present invention has the following beneficial effects:

[0108] (1) For a hot field environment with silicon vapor corrosion, the coated carbon fiber hard felt provided by the present invention is silicon and carbon after being subjected to high temperature, and is the same object as the product in the hot field environment, thereby greatly reducing the pollution in the furnace.

[0109] (2) The substance produced by adding silicon-containing substances at high temperature during the preparation process is the same as the substance in the use environment. It is simpler and less expensive than the existing preparation method of depositing SiC on the surface. At the same time, the obtained product is combined with carbon fiber filaments to provide higher hardness for carbon fiber felt.

[0110] (3) The surface coating method is simple, the configured coating material is easy to prepare, the product obtained after high temperature is single and has few impurities, and after purification, a hard felt with an impurity content below 5 ppm can be easily obtained.

[0111] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a coated carbon fiber hard felt, characterized in that: The following steps are involved: a) chopping, combing, drawing and needle punching the carbon fiber precursor in sequence to obtain a soft felt; then coating the raw fiber with a curing resin to obtain a soft felt coated with a resin; The curing resin is a mixed resin material of one or more of polycarbosilane, dimethylsilane, methyltriethoxysilane and phenolic resin; b) drying the soft felt coated with glue obtained in step a) and curing the glue to obtain a cured felt body; c) The solidified felt obtained in step b) is sequentially subjected to carbonization treatment, graphitization treatment, and surface cleaning, and then sprayed with a coating material to form a coating. After the coating is solidified, it is purified to obtain a coated carbon fiber hard felt.

2. The preparation method according to claim 1, characterized in that The chopped length in step a) is 40 mm to 60 mm; the pulling arranges 95% to 100% of the carbon filaments in the same direction; and the soft felt obtained by the needle punching and compounding has a thickness of 5 mm to 10 mm.

3. The preparation method according to claim 1, characterized in that The temperature for drying the moisture in step b) is 40° C. to 70° C., and the time is 0.5 h to 2 h.

4. The preparation method according to claim 1, characterized in that The glue is cured in step b) at a pressure of 0.1 MPa to 0.5 MPa, a temperature of 130° C. to 165° C., and a time of 3 h to 6 h.

5. The preparation method according to claim 1, characterized in that The carbonization process in step c) is specifically as follows: The heating time from rt to 200℃ is 100min~200min, the heating time from 200℃ to 500℃ is 150min~200min, the heating time from 500℃ to 800℃ is 200min~350min, and the heat preservation time at 800℃ is 6h~9h; or, The heating time from rt to 250℃ is 150min~220min, the heating time from 250℃ to 600℃ is 200min~310min, the heating time from 600℃ to 800℃ is 80min~160min, and the heat preservation time at 800℃ is 6h~9h; or, The heating time from rt to 200℃ is 150min~240min, the heating time from 200℃ to 400℃ is 90min~150min, the heating time from 400℃ to 800℃ is 200min~280min, and the insulation time at 800℃ is 6h~9h.

6. The preparation method according to claim 1, characterized in that The graphitization process in step c) is specifically as follows: The carbonized felt is placed in a graphitization furnace and counterweighted with graphite plates 1 to 3 times larger than its own weight. The graphitization temperature is 1800°C to 2400°C and the time is 4 to 8 hours.

7. The preparation method according to claim 1, characterized in that The coating material in step c) is: 1wt% to 3wt% thickener, 8wt% to 20wt% powdered phenolic resin, 15wt% to 25wt% phenyltrimethoxysilane, 50wt% to 70wt% pure water, 5wt% to 10wt% carbon powder; or, 0.5wt% to 2wt% thickener, 10wt% to 25wt% powdered phenolic resin, 10wt% to 20wt% polymethylsilane, 50wt% to 70wt% pure water, 5wt% to 10wt% carbon powder; or, 1wt% to 3wt% thickener, 10wt% to 25wt% powdered phenolic resin, 10wt% to 25wt% polydimethylsiloxane, 50wt% to 70wt% pure water, 5wt% to 10wt% carbon powder, and 4wt% to 8wt% silane coupling agent; The coating formed by spraying has a thickness of 0.5 mm to 1 mm.

8. The preparation method according to claim 1, characterized in that The coating is cured at a temperature of 140° C. to 200° C. for 2 to 5 hours in step c). The temperature of the purification treatment is 2000°C to 2400°C.

9. A carbon fiber hard felt with a coating, characterized in that: The preparation method is described in any one of claims 1 to 8.