Preparation method of composite hard felt thermal field material of high-pressure gas quenching furnace

Abstract

The invention discloses a preparation method of a composite hard felt thermal field material of a high-pressure gas quenching furnace. The preparation method comprises the following steps: step 1, preparing a mold required for producing a hard felt cylinder; 2, soft felt is soaked, and the soaked soft felt is wound on the periphery of the mold; 3, after winding of the soft felt is completed, baking and shaping treatment is conducted; 4, separating the hard felt cylinder from the mold after shaping, and carrying out graphitization treatment; and 5, purifying to obtain a hard felt cylinder finished product. Step 6, preparing a mold required by production of the composite carbon-carbon inner layer; seventhly, the carbon fibers are wound on a mold after being glued, shaping and demolding are conducted, and densification treatment is conducted; step 8, carrying out graphitization treatment; and 9, purifying to obtain a composite carbon-carbon inner layer finished product. And 10, fixedly connecting the hard felt cylinder finished product with the composite carbon-carbon inner layer finished product. The density and structural strength of the hard felt cylinder finished product and the composite carbon-carbon inner layer finished product can be improved, so that the safety of the hard felt cylinder finished product and the composite carbon-carbon inner layer finished product during use is improved, and safe production is ensured.

Description

Technical Field

[0001] The invention belongs to the field of production of composite hard felt thermal field materials for high-pressure gas quenching furnaces, in particular to a method for preparing composite hard felt thermal field materials for high-pressure gas quenching furnaces. Background Art

[0002] High pressure gas quenching furnace is an advanced heat treatment equipment, which is widely used in the processing of metal materials. Its working principle mainly relies on the rapid cooling effect of high pressure gas to achieve the purpose of quenching metal materials.

[0003] The hard felt cylinder is an important component of the high pressure gas quenching furnace. As a special fiber material, the hard felt cylinder usually has excellent high temperature resistance, sealing and certain mechanical strength. It is often used as the insulation layer or sealing layer of the high pressure gas quenching furnace to effectively reduce heat loss and maintain the vacuum or specific atmosphere in the furnace.

[0004] The hard felt cylinder of the current high-pressure gas quenching furnace needs to withstand greater pressure when used in a vacuum environment, so higher requirements are placed on its performance. The hard felt cylinder of the current high-pressure gas quenching furnace has a shorter service life during use. Summary of the invention

[0005] The invention provides a method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace, which is used to solve the defects in the prior art.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace comprises the following steps:

[0008] Step 1: Prepare the mold required for the production of hard felt tubes according to the model of the high-pressure gas quenching furnace;

[0009] Step 2: soaking the soft felt with a liquid resin material, and winding the soaked soft felt around the outer periphery of the mold prepared in step 1, and selecting the number of winding layers of the soft felt according to a preset thickness;

[0010] Step 3: After the soft felt is wound, it is baked and shaped;

[0011] Step 4: After shaping, the hard felt tube is separated from its mold, and the separated hard felt tube is sent to a graphitization furnace for graphitization treatment;

[0012] Step 5: The graphitized hard felt cylinder is purified to obtain a finished hard felt cylinder;

[0013] Step 6: Select the same high pressure gas quenching furnace model as in step 1 to prepare the mold required for the production of the composite carbon-carbon inner layer;

[0014] Step 7: The outer periphery of the mold prepared in step 6 is wound with glued carbon fiber to a specified thickness, and then shaped and demoulded to perform a densification treatment;

[0015] Step 8: After the densification treatment is completed, the composite carbon-carbon inner layer is sent to a graphitization furnace for graphitization treatment;

[0016] Step nine: the graphitized composite carbon-carbon inner layer is purified to obtain a finished composite carbon-carbon inner layer;

[0017] Step 10: Fix and connect the hard felt tube product obtained in step 5 and the composite carbon-carbon inner layer product obtained in step 9.

[0018] According to the method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace as described above, the mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six are both made of 304 stainless steel, and reinforcing ribs are welded in the middle of the mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six to facilitate the connection of the internal rotating shaft; the surface roughness of the mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six is ​​lower than 0.8; a layer of PTFE release paper is applied to the outer surface of the mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six, and the thickness of the PTFE release paper is 0.5 mm.

[0019] In the above-mentioned method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace, the liquid resin in step 2 is a phenolic resin, and the soaking time of the soft felt is 10-20 minutes.

[0020] According to the method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace as described above, the soft felt in the step 2 needs to be close to the mold surface during the winding process, and after winding one layer, it needs to be compacted again by a roller, and a layer of graphite carbon foil is arranged between two adjacent layers of soft felt. After all the soft felts are wound, they are placed between the upper mold and the lower mold, and the upper mold and the lower mold are fixedly connected on both sides by bolts, so as to further compact the wound soft felt and increase its density. The thickness of the soft felt is 8-10mm, and the thickness of the graphite carbon foil is 0.4-0.6mm.

[0021] According to the method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace as described above, the baking and shaping treatment in step three includes the following operations: placing the wound soft felt together with the mold into a blast oven, heating the temperature to 60-80°C for 1 hour and keeping the temperature for 30 minutes, then heating the temperature to 80-120°C for 1 hour and keeping the temperature for 1 hour, and finally heating the temperature to 120-240°C for 3 hours and keeping the temperature for 1 hour; and air cooling to room temperature after the operation is completed.

[0022] According to the method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace as described above, the specific operations of the graphitization treatment in step four and step eight are as follows: the shaped hard felt tube or the densified composite carbon-carbon inner layer is sent into the graphitization furnace, and then nitrogen is introduced to maintain an oxygen-free environment, and then the temperature is increased, and the heating rate is controlled at 100-200°C / h, and the temperature is increased to 2200°C, and then the temperature is kept for 18-24h, and then the heating is stopped and the nitrogen is kept introduced. After the temperature drops to 100°C, the nitrogen is stopped, and the material can be taken out after cooling to room temperature.

[0023] According to the method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace as described above, the specific operation of purifying the graphitized hard felt tube in step five and the graphitized composite carbon-carbon inner layer in step nine is as follows: soaking the graphitized hard felt tube and the graphitized composite carbon-carbon inner layer in a hydrochloric acid solution with a concentration of 5-10%, taking them out after soaking, rinsing them with clean water for 3-5 times, and then drying them with hot air at 60-80°C.

[0024] In the method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace as described above, the carbon fiber in step seven is T700-12k carbon fiber yarn, the carbon fiber is wound in a hoop or spiral direction, the winding thickness is 3-5mm, and liquid phenolic resin is used for gluing. Before winding, the gluing can be completed by passing through a trough filled with liquid phenolic resin.

[0025] According to the method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace as described above, the specific operation of the densification treatment in step seven is: putting the carbon fiber after winding and demolding into a heating furnace, introducing nitrogen to remove the air, then heating to 1100°C, and then introducing methane gas to keep warm for 2-3 hours, then stopping heating, cooling to room temperature and taking out.

[0026] According to the method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace as described above, the methods for fixing and connecting the hard felt tube product obtained in step five of step ten and the composite carbon-carbon inner layer product obtained in step nine include: sewing, bolting, and chemical connection.

[0027] The advantages of the present invention are as follows: the present invention increases the mechanical properties of the hard felt cylinder by arranging a composite carbon-carbon inner layer on the inner side of the hard felt cylinder, thereby enabling the hard felt cylinder to be used stably for a long time, thereby increasing its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 is a flow chart of the present invention;

[0030] Figure 2 It is a schematic diagram of the cooperation between the hard felt tube and the mold of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] like Figure 1 As shown, a method for preparing a composite hard felt thermal field material for a high-pressure gas quenching furnace comprises the following steps:

[0033] Step 1: Prepare the mold required for the production of hard felt tubes according to the model of the high-pressure gas quenching furnace;

[0034] Step 2: soaking the soft felt with a liquid resin material, and winding the soaked soft felt around the outer periphery of the mold prepared in step 1, and selecting the number of winding layers of the soft felt according to a preset thickness;

[0035] Step 3: After the soft felt is wound, it is baked and shaped;

[0036] Step 4: After shaping, the hard felt tube is separated from its mold, and the separated hard felt tube is sent to a graphitization furnace for graphitization treatment;

[0037] Step 5: The graphitized hard felt cylinder is purified to obtain a finished hard felt cylinder;

[0038] Step 6: Select the same high pressure gas quenching furnace model as in step 1 to prepare the mold required for the production of the composite carbon-carbon inner layer;

[0039] Step 7: The outer periphery of the mold prepared in step 6 is wound with glued carbon fiber to a specified thickness, and then shaped and demoulded to perform a densification treatment;

[0040] Step 8: After the densification treatment is completed, the composite carbon-carbon inner layer is sent to a graphitization furnace for graphitization treatment;

[0041] Step nine: the graphitized composite carbon-carbon inner layer is purified to obtain a finished composite carbon-carbon inner layer;

[0042] Step 10: Fix and connect the hard felt tube product obtained in step 5 and the composite carbon-carbon inner layer product obtained in step 9.

[0043] Specifically, the mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six described in this embodiment are both made of 304 stainless steel, and the mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six have welded reinforcing ribs in the middle to facilitate the connection of the internal rotating shaft; the surface roughness of the mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six is ​​lower than 0.8; a layer of PTFE release paper is affixed to the outer surface of the mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six, and the thickness of the PTFE release paper is 0.5 mm.

[0044] Specifically, the liquid resin in step 2 of this embodiment is phenolic resin (brand TC-02, manufacturer Jinan Shengquan Group Co., Ltd.), and the soft felt is soaked for 10-20 minutes.

[0045] More specifically, in step 2 described in this embodiment, the soft felt needs to be close to the mold surface during the winding process, and needs to be compacted again by a roller after winding one layer. A layer of graphite carbon foil is arranged between two adjacent layers of soft felt. After all the soft felts are wound, they are placed between the upper mold and the lower mold. The upper mold and the lower mold are fixedly connected on both sides by bolts, so as to further compact the wound soft felt and increase its density. The thickness of the soft felt is 8-10mm, and the thickness of the graphite carbon foil is 0.4-0.6mm.

[0046] More specifically, the baking and shaping treatment in step three described in this embodiment includes the following operations: placing the wound soft felt together with the mold into a blast oven, heating it to 60-80°C, heating time for 1 hour, keeping it warm for 30 minutes, then heating it to 80-120°C, heating time for 1 hour, keeping it warm for 1 hour, and finally heating it to 120-240°C, heating time for 3 hours, keeping it warm for 1 hour; after the operation is completed, air cool it to room temperature.

[0047] More specifically, the specific operations of the graphitization treatment in step 4 and step 8 described in this embodiment are: the shaped hard felt tube or the densified composite carbon-carbon inner layer is sent into the graphitization furnace, and then nitrogen is introduced to maintain an oxygen-free environment, and then the temperature is increased, and the heating rate is controlled at 100-200°C / h, and the temperature is increased to 2200°C, and then the temperature is kept for 18-24h, and then the heating is stopped and the nitrogen is kept introduced. After the temperature drops to 100°C, the nitrogen is stopped, and it can be taken out after cooling to room temperature.

[0048] Furthermore, the specific operation of the purification treatment of the graphitized hard felt tube in step five and the graphitized composite carbon-carbon inner layer in step nine described in this embodiment is: soak the graphitized hard felt tube and the graphitized composite carbon-carbon inner layer in a hydrochloric acid solution with a concentration of 5-10%, take them out after soaking, rinse them with clean water for 3-5 times, and then blow dry them with hot air at 60-80°C.

[0049] Furthermore, the carbon fiber in step seven described in this embodiment is T700-12k carbon fiber yarn (manufacturer Zhongfu Shenying Carbon Fiber Co., Ltd.), the carbon fiber is wound in a hoop or spiral manner, the winding thickness is 3-5mm, and liquid phenolic resin (grade TC-02, manufacturer Jinan Shengquan Group Co., Ltd.) is used for gluing. Before winding, the gluing can be completed by passing through a tank filled with liquid phenolic resin.

[0050] Furthermore, the specific operation of the densification treatment in step seven described in this embodiment is: put the carbon fiber after winding and demolding into a heating furnace, introduce nitrogen to remove the air, then increase the temperature to 1100°C, and then introduce methane gas to keep warm for 2-3 hours, then stop heating and cool to room temperature before taking out.

[0051] Furthermore, the methods for fixing and connecting the hard felt tube product obtained in step five of step ten described in this embodiment and the composite carbon-carbon inner layer product obtained in step nine include: sewing, bolting, and chemical connection; the sewing is to use graphite rope for suturing and fixing; the bolting connection is to use mechanical fixing by bolt punching; the chemical connection is to use brazing treatment for fixing.

[0052] Preferably, the brazing treatment described in this embodiment uses Ti-Cu-Be brazing filler metal for brazing, and the surface of the carbon / carbon composite material is modified before brazing. A layer of epoxy resin is coated on the inner surface of the hard felt tube finished product and the outer surface of the composite carbon-carbon inner layer, and carbonization operation is performed at 1600°C in a vacuum or argon environment for 1 hour, so that a dense carbon layer is generated on the inner surface of the hard felt tube finished product and the outer surface of the composite carbon-carbon inner layer, thereby achieving the purpose of modification, not only improving the density of the carbon layer on the inner surface of the hard felt tube finished product and the outer surface of the composite carbon-carbon inner layer, but also preventing the infiltration of molten brazing filler. After the modification of the inner surface of the hard felt tube finished product and the outer surface of the composite carbon-carbon inner layer is completed, the Ti-Cu-Be brazing filler is uniformly coated on the inner surface of the hard felt tube finished product and the outer surface of the composite carbon-carbon inner layer, and then the composite carbon-carbon inner layer is inserted into the interior of the hard felt tube finished product, and sent into the brazing furnace for vacuum brazing at 1200°C for 1 hour and then cooled to room temperature.

[0053] Preferably, the brazing process described in this embodiment uses a brazing flux including the following substances in parts by weight: 15 parts of graphite, 10 parts of boron carbide, 25 parts of boron phenolic resin, and 10 parts of chopped fibers; the brazing flux is evenly coated on the inner surface of the hard felt tube product and the outer surface of the composite carbon-carbon inner layer, and then the composite carbon-carbon inner layer is inserted into the interior of the hard felt tube product, and sent into a brazing furnace for vacuum brazing at 1000°C for 1 hour and then cooled to room temperature.

[0054] Preferably, the hard felt tube product and the composite carbon-carbon inner layer product prepared as described in this embodiment need to be measured again after graphitization treatment. If the dimensional deformation exceeds 0.2%, it is defined as an unqualified product and cannot be sold or used, thereby avoiding safety accidents caused by the use of unqualified products.

[0055] Example 1

[0056] Step 1: Use 304 stainless steel to prepare a mold for the production of a hard felt tube with a size of φ1250*1500mm, the surface roughness of the mold required for the production of the hard felt tube is 0.7, and a layer of PTFE release paper is pasted on the outer surface of the mold required for the production of the hard felt tube, and the thickness of the PTFE release paper is 0.5mm;

[0057] Step 2: Put the soft felt into liquid phenolic resin (grade TC-02, manufacturer Jinan Shengquan Group Co., Ltd.) and soak it for 10 minutes. The soaked soft felt is wound around the periphery of the mold prepared in step 1. In step 2, the soft felt needs to be close to the mold surface during the winding process. After winding one layer, it needs to be compacted again by a roller. A layer of graphite carbon foil is set between two adjacent layers of soft felt. After all the soft felts are wound, they are placed between the upper mold and the lower mold. The upper mold and the lower mold are fixedly connected on both sides by bolts, so as to further compact the wound soft felt and increase the density. The thickness of the soft felt is 8 mm, and the thickness of the graphite carbon foil is 0.4 mm. Finally, 6 layers of soft felt and 5 layers of graphite carbon foil are used, and the final thickness is: 40 mm;

[0058] Step 3: After the soft felt is wound, put the wound soft felt and the mold into a blast oven, heat it to 60°C, heat it up for 1 hour, keep it warm for 30 minutes, then heat it up to 80°C, heat it up for 1 hour, keep it warm for 1 hour, and finally heat it up to 120°C, heat it up for 3 hours, keep it warm for 1 hour; after the operation is completed, air cool it to room temperature;

[0059] Step 4: After shaping, separate the hard felt tube from its mold, send the separated hard felt tube into the graphitization furnace, and then introduce nitrogen to maintain an oxygen-free environment, and then heat up at a rate of 100°C / h to 2200°C, then keep warm for 18 hours, stop heating and keep introducing nitrogen, stop introducing nitrogen after cooling to 100°C, and take out after cooling to room temperature;

[0060] Step 5: The graphitized hard felt tube is immersed in a 5% hydrochloric acid solution, taken out after immersion, rinsed with clean water for 3 times, and then dried with hot air at 60°C to obtain a finished hard felt tube;

[0061] Step 6: Use 304 stainless steel to prepare a mold for composite carbon-carbon inner layer production with a size of φ1247*1500mm, the surface roughness of the mold for composite carbon-carbon inner layer production is 0.7, and a layer of PTFE release paper is applied to the outer surface of the mold for composite carbon-carbon inner layer production, and the thickness of the PTFE release paper is 0.5mm;

[0062] Step 7: Carbon fiber winding is performed on the periphery of the mold prepared in step 6. The carbon fiber is T700-12k carbon fiber yarn (manufacturer Zhongfu Shenying Carbon Fiber Co., Ltd.), the carbon fiber is hoop-wound, and liquid phenolic resin (grade TC-02, manufacturer Jinan Shengquan Group Co., Ltd.) is used for sizing. Before winding, the sizing can be completed by a tank body filled with liquid phenolic resin. The winding thickness is 3mm. After the winding is completed, the shaping and demoulding are completed. The carbon fiber after the winding and demoulding is placed in a heating furnace and nitrogen is passed to remove the air, and then the temperature is raised to 1100°C, and then methane gas is passed to keep the temperature for 2h, and then the heating is stopped and cooled to room temperature and taken out;

[0063] Step 8: After the densification treatment is completed, the composite carbon-carbon inner layer is sent to the graphitization furnace, and then nitrogen is introduced to maintain an oxygen-free environment, and then the temperature is increased, and the heating rate is controlled at 100°C / h, and the temperature is increased to 2200°C, and then the heating is stopped after 18 hours of heat preservation and the nitrogen is kept introduced. After the temperature drops to 100°C, the nitrogen is stopped, and it can be taken out after cooling to room temperature;

[0064] Step nine: the graphitized composite carbon-carbon inner layer is immersed in a 5% hydrochloric acid solution, taken out after immersion, rinsed with clean water for 3 times, and then dried with hot air at 60°C to obtain a finished composite carbon-carbon inner layer;

[0065] Step 10: The hard felt tube product obtained in step 5 and the composite carbon-carbon inner layer product obtained in step 9 are sutured and fixedly connected by a graphite rope.

[0066] Example 2

[0067] Step 1: Use 304 stainless steel to prepare a mold for the production of a hard felt tube with a size of φ1250*1500mm, the surface roughness of the mold required for the production of the hard felt tube is 0.7, and a layer of PTFE release paper is pasted on the outer surface of the mold required for the production of the hard felt tube, and the thickness of the PTFE release paper is 0.5mm;

[0068] Step 2: Put the soft felt into liquid phenolic resin (grade TC-02, manufacturer Jinan Shengquan Group Co., Ltd.) and soak it for 120 minutes. The soaked soft felt is wound around the periphery of the mold prepared in step 1. In step 2, the soft felt needs to be close to the mold surface during the winding process. After winding one layer, it needs to be compacted again by a roller. A layer of graphite carbon foil is set between two adjacent layers of soft felt. After all the soft felts are wound, they are placed between the upper mold and the lower mold. The upper mold and the lower mold are fixedly connected on both sides by bolts, so as to further compact the wound soft felt and increase the density. The thickness of the soft felt is 10 mm, and the thickness of the graphite carbon foil is 0.6 mm. Finally, 6 layers of soft felt and 5 layers of graphite carbon foil are used, and the final thickness is: 51 mm;

[0069] Step 3: After the soft felt is wound, put the wound soft felt and the mold into a blast oven, heat it to 80°C, heat it up for 1 hour, keep it warm for 30 minutes, then heat it up to 120°C, heat it up for 1 hour, keep it warm for 1 hour, and finally heat it up to 240°C, heat it up for 3 hours, keep it warm for 1 hour; after the operation is completed, air cool it to room temperature;

[0070] Step 4: After shaping, separate the hard felt tube from its mold, send the separated hard felt tube into the graphitization furnace, and then introduce nitrogen to maintain an oxygen-free environment, and then heat up at a rate of 200°C / h to 2200°C, then keep warm for 18-24h, stop heating and keep introducing nitrogen, stop introducing nitrogen after cooling to 100°C, and take out after cooling to room temperature;

[0071] Step 5: The graphitized hard felt tube is immersed in a 10% hydrochloric acid solution, and after immersion, it is taken out and rinsed with clean water for 5 times, and then dried with hot air at 80°C to obtain a finished hard felt tube;

[0072] Step 6: Use 304 stainless steel to prepare a mold for composite carbon-carbon inner layer production with a size of φ1245*1500mm, the surface roughness of the mold for composite carbon-carbon inner layer production is 0.7, and a layer of PTFE release paper is applied to the outer surface of the mold for composite carbon-carbon inner layer production, and the thickness of the PTFE release paper is 0.5mm;

[0073] Step 7: Carbon fiber is wound around the periphery of the mold prepared in step 6. The carbon fiber is T700-12k carbon fiber yarn (manufacturer Zhongfu Shenying Carbon Fiber Co., Ltd.). The carbon fiber is wound in a spiral and sizing is performed using liquid phenolic resin (grade TC-02, manufacturer Jinan Shengquan Group Co., Ltd.). Before winding, the sizing can be completed by a tank body filled with liquid phenolic resin. The winding thickness is 5 mm. After the winding is completed, the carbon fiber is shaped and demolded. The carbon fiber after the winding is completed and demolded is placed in a heating furnace and nitrogen is passed to remove air. The temperature is then raised to 1100°C, and then methane gas is passed to keep the temperature for 2-3 hours, then the heating is stopped, cooled to room temperature, and then taken out;

[0074] Step 8: After the densification treatment is completed, the composite carbon-carbon inner layer is sent to the graphitization furnace, and then nitrogen is introduced to maintain an oxygen-free environment, and then the temperature is increased, and the heating rate is controlled at 200°C / h, and the temperature is increased to 2200°C. Then, after keeping the temperature for 24 hours, the heating is stopped and the nitrogen is kept introduced. After the temperature drops to 100°C, the nitrogen is stopped, and it can be taken out after cooling to room temperature;

[0075] Step nine: the graphitized composite carbon-carbon inner layer is immersed in a 10% hydrochloric acid solution, taken out after immersion, rinsed with clean water 5 times, and then dried with 80°C hot air to obtain a finished composite carbon-carbon inner layer;

[0076] Step 10: The hard felt tube product obtained in step 5 and the composite carbon-carbon inner layer product obtained in step 9 are mechanically fixed and connected by bolt punching.

[0077] Example 3

[0078] Step 1: Use 304 stainless steel to prepare a mold for the production of a hard felt tube with a size of φ1250*1500mm, the surface roughness of the mold required for the production of the hard felt tube is 0.7, and a layer of PTFE release paper is pasted on the outer surface of the mold required for the production of the hard felt tube, and the thickness of the PTFE release paper is 0.5mm;

[0079] Step 2: Put the soft felt into liquid phenolic resin (grade TC-02, manufacturer Jinan Shengquan Group Co., Ltd.) and soak it for 15 minutes. The soaked soft felt is wound around the periphery of the mold prepared in step 1. In step 2, the soft felt needs to be close to the mold surface during the winding process. After winding one layer, it needs to be compacted again by a roller. A layer of graphite carbon foil is set between two adjacent layers of soft felt. After all the soft felts are wound, they are placed between the upper mold and the lower mold. The upper mold and the lower mold are fixedly connected on both sides by bolts, so as to further compact the wound soft felt and increase the density. The thickness of the soft felt is 9 mm, and the thickness of the graphite carbon foil is 0.5 mm. Finally, 6 layers of soft felt and 5 layers of graphite carbon foil are used, and the final thickness is: 43 mm;

[0080] Step 3: After the soft felt is wound, put the wound soft felt and the mold into a blast oven, heat it to 70°C, heat it up for 1 hour, keep it warm for 30 minutes, then heat it up to 100°C, heat it up for 1 hour, keep it warm for 1 hour, and finally heat it up to 180°C, heat it up for 3 hours, keep it warm for 1 hour; after the operation is completed, air cool it to room temperature;

[0081] Step 4: After shaping, separate the hard felt tube from its mold, send the separated hard felt tube into the graphitization furnace, and then introduce nitrogen to maintain an oxygen-free environment, and then heat up at a rate of 150°C / h to 2200°C, then keep warm for 21 hours, stop heating and keep introducing nitrogen, stop introducing nitrogen after cooling to 100°C, and take it out after cooling to room temperature;

[0082] Step 5: The graphitized hard felt tube is immersed in a hydrochloric acid solution with a concentration of 8%, and after the immersion is completed, it is taken out and rinsed with clean water for 4 times, and then blown dry with hot air at 70°C to obtain a finished hard felt tube;

[0083] Step 6: Use 304 stainless steel to prepare a mold for composite carbon-carbon inner layer production with a size of φ1246*1500mm, the surface roughness of the mold for composite carbon-carbon inner layer production is 0.7, and a layer of PTFE release paper is applied to the outer surface of the mold for composite carbon-carbon inner layer production, and the thickness of the PTFE release paper is 0.5mm;

[0084] Step 7: Carbon fiber is wound around the periphery of the mold prepared in step 6. The carbon fiber is T700-12k carbon fiber yarn (manufacturer Zhongfu Shenying Carbon Fiber Co., Ltd.). The carbon fiber is wound in a spiral and sizing is performed using liquid phenolic resin (grade TC-02, manufacturer Jinan Shengquan Group Co., Ltd.). Before winding, the sizing can be completed by a tank body filled with liquid phenolic resin. The winding thickness is 4mm. After the winding is completed, the carbon fiber is shaped and demolded. The carbon fiber after the winding is completed and demolded is placed in a heating furnace and nitrogen is passed to remove air. The temperature is then raised to 1100°C, and then methane gas is passed to keep the temperature for 2-3h, then the heating is stopped, cooled to room temperature, and then taken out;

[0085] Step 8: After the densification treatment is completed, the composite carbon-carbon inner layer is sent to the graphitization furnace, and then nitrogen is introduced to maintain an oxygen-free environment, and then the temperature is increased, and the heating rate is controlled at 150°C / h to 2200°C, and then the heating is stopped after 21 hours of heat preservation and nitrogen is kept introduced. After the temperature drops to 100°C, the nitrogen is stopped, and it can be taken out after cooling to room temperature;

[0086] Step nine: the graphitized composite carbon-carbon inner layer is immersed in a hydrochloric acid solution with a concentration of 8%, taken out after the immersion is completed, rinsed with clean water for 4 times, and then dried with hot air at 70°C to obtain a finished composite carbon-carbon inner layer;

[0087] Step 10: The finished hard felt tube obtained in step 5 and the finished composite carbon-carbon inner layer obtained in step 9 are fixedly connected by brazing with Ti-Cu-Be brazing filler, and the surface of the carbon / carbon composite material is modified before brazing. A layer of epoxy resin is coated on the inner surface of the finished hard felt tube and the outer surface of the composite carbon-carbon inner layer, and carbonization is performed at 1600°C in a vacuum or argon environment for 1 hour, so that a dense carbon layer is generated on the inner surface of the finished hard felt tube and the outer surface of the composite carbon-carbon inner layer, thereby achieving the purpose of modification, which not only improves the density of the carbon layer on the inner surface of the finished hard felt tube and the outer surface of the composite carbon-carbon inner layer, but also prevents the penetration of molten brazing filler. After the modification of the inner surface of the finished hard felt tube and the outer surface of the composite carbon-carbon inner layer is completed, the Ti-Cu-Be brazing filler is evenly coated on the inner surface of the finished hard felt tube and the outer surface of the composite carbon-carbon inner layer, and then the composite carbon-carbon inner layer is inserted into the interior of the finished hard felt tube, and sent into the brazing furnace for vacuum brazing at 1200°C for 1 hour and then cooled to room temperature.

[0088] Comparative Example 1

[0089] Step 1: Use 304 stainless steel to prepare a mold for the production of a hard felt tube with a size of φ1250*1500mm, the surface roughness of the mold required for the production of the hard felt tube is 0.7, and a layer of PTFE release paper is pasted on the outer surface of the mold required for the production of the hard felt tube, and the thickness of the PTFE release paper is 0.5mm;

[0090] Step 2: Put the soft felt into liquid phenolic resin (grade TC-02, manufacturer Jinan Shengquan Group Co., Ltd.) and soak it for 10 minutes. The soaked soft felt is wound around the periphery of the mold prepared in step 1. In step 2, the soft felt needs to be close to the mold surface during the winding process. After winding one layer, it needs to be compacted again by a roller. A layer of graphite carbon foil is set between two adjacent layers of soft felt. After all the soft felts are wound, they are placed between the upper mold and the lower mold. The upper mold and the lower mold are fixedly connected on both sides by bolts, so as to further compact the wound soft felt and increase the density. The thickness of the soft felt is 8 mm, and the thickness of the graphite carbon foil is 0.4 mm. Finally, 6 layers of soft felt and 5 layers of graphite carbon foil are used, and the final thickness is: 40 mm;

[0091] Step 3: After the soft felt is wound, put the wound soft felt and the mold into a blast oven, heat it to 60°C, heat it up for 1 hour, keep it warm for 30 minutes, then heat it up to 80°C, heat it up for 1 hour, keep it warm for 1 hour, and finally heat it up to 120°C, heat it up for 3 hours, keep it warm for 1 hour; after the operation is completed, air cool it to room temperature;

[0092] Step 4: After shaping, separate the hard felt tube from its mold, send the separated hard felt tube into the graphitization furnace, and then introduce nitrogen to maintain an oxygen-free environment, and then heat up at a rate of 100°C / h to 2200°C, then keep warm for 18 hours, stop heating and keep introducing nitrogen, stop introducing nitrogen after cooling to 100°C, and take out after cooling to room temperature;

[0093] Step 5: The graphitized hard felt tube is immersed in a 5% hydrochloric acid solution, taken out after immersion, rinsed with clean water for 3 times, and then dried with hot air at 60°C to obtain a finished hard felt tube.

[0094] Comparative Example 2

[0095] Step 1: Use 304 stainless steel to prepare a mold for the production of a hard felt tube with a size of φ1250*1500mm, the surface roughness of the mold required for the production of the hard felt tube is 0.7, and a layer of PTFE release paper is pasted on the outer surface of the mold required for the production of the hard felt tube, and the thickness of the PTFE release paper is 0.5mm;

[0096] Step 2: Put the soft felt into liquid phenolic resin (grade TC-02, manufacturer Jinan Shengquan Group Co., Ltd.) and soak it for 120 minutes. The soaked soft felt is wound around the periphery of the mold prepared in step 1. In step 2, the soft felt needs to be close to the mold surface during the winding process. After winding one layer, it needs to be compacted again by a roller. A layer of graphite carbon foil is set between two adjacent layers of soft felt. After all the soft felts are wound, they are placed between the upper mold and the lower mold. The upper mold and the lower mold are fixedly connected on both sides by bolts, so as to further compact the wound soft felt and increase the density. The thickness of the soft felt is 10 mm, and the thickness of the graphite carbon foil is 0.6 mm. Finally, 6 layers of soft felt and 5 layers of graphite carbon foil are used, and the final thickness is: 51 mm;

[0097] Step 3: After the soft felt is wound, put the wound soft felt and the mold into a blast oven, heat it to 80°C, heat it up for 1 hour, keep it warm for 30 minutes, then heat it up to 120°C, heat it up for 1 hour, keep it warm for 1 hour, and finally heat it up to 240°C, heat it up for 3 hours, keep it warm for 1 hour; after the operation is completed, air cool it to room temperature;

[0098] Step 4: After shaping, separate the hard felt tube from its mold, send the separated hard felt tube into the graphitization furnace, and then introduce nitrogen to maintain an oxygen-free environment, and then heat up at a rate of 200°C / h to 2200°C, then keep warm for 18-24h, stop heating and keep introducing nitrogen, stop introducing nitrogen after cooling to 100°C, and take out after cooling to room temperature;

[0099] Step 5: The graphitized hard felt tube is immersed in a 10% hydrochloric acid solution, and after immersion, it is taken out and rinsed with clean water for 5 times, and then dried with hot air at 80°C to obtain a finished hard felt tube.

[0100] Comparative Example 3

[0101] Step 1: Use 304 stainless steel to prepare a mold for the production of a hard felt tube with a size of φ1250*1500mm, the surface roughness of the mold required for the production of the hard felt tube is 0.7, and a layer of PTFE release paper is pasted on the outer surface of the mold required for the production of the hard felt tube, and the thickness of the PTFE release paper is 0.5mm;

[0102] Step 2: Put the soft felt into liquid phenolic resin (grade TC-02, manufacturer Jinan Shengquan Group Co., Ltd.) and soak it for 15 minutes. The soaked soft felt is wound around the periphery of the mold prepared in step 1. In step 2, the soft felt needs to be close to the mold surface during the winding process. After winding one layer, it needs to be compacted again by a roller. A layer of graphite carbon foil is set between two adjacent layers of soft felt. After all the soft felts are wound, they are placed between the upper mold and the lower mold. The upper mold and the lower mold are fixedly connected on both sides by bolts, so as to further compact the wound soft felt and increase the density. The thickness of the soft felt is 9 mm, and the thickness of the graphite carbon foil is 0.5 mm. Finally, 6 layers of soft felt and 5 layers of graphite carbon foil are used, and the final thickness is: 43 mm;

[0103] Step 3: After the soft felt is wound, put the wound soft felt and the mold into a blast oven, heat it to 70°C, heat it up for 1 hour, keep it warm for 30 minutes, then heat it up to 100°C, heat it up for 1 hour, keep it warm for 1 hour, and finally heat it up to 180°C, heat it up for 3 hours, keep it warm for 1 hour; after the operation is completed, air cool it to room temperature;

[0104] Step 4: After shaping, separate the hard felt tube from its mold, send the separated hard felt tube into the graphitization furnace, and then introduce nitrogen to maintain an oxygen-free environment, and then heat up at a rate of 150°C / h to 2200°C, then keep warm for 21 hours, stop heating and keep introducing nitrogen, stop introducing nitrogen after cooling to 100°C, and take it out after cooling to room temperature;

[0105] Step 5: The graphitized hard felt tube is immersed in a hydrochloric acid solution with a concentration of 8%. After the immersion is completed, it is taken out and rinsed with clean water for 4 times, and then dried with hot air at 70°C to obtain a finished hard felt tube.

[0106] Verification test

[0107] The performance tests were conducted on the finished hard felt tubes and composite carbon-carbon inner layer products prepared in Examples 1-3 and the finished hard felt tubes prepared in Comparative Examples 1-3. The results are shown in Table 1.

[0108] Group <![CDATA[Overall density (g / cm 3 )]]> Compressive strength(MPa) Tensile strength(MPa) Example 1 0.19 201 73 Example 2 0.19 205 75 Example 3 0.19 203 76 Comparative Example 1 0.19 172 61 Comparative Example 2 0.19 178 63 Comparative Example 3 0.19 179 62

[0109] Table 1

[0110] It can be seen from the data in Table 1 that although the overall density of the hard felt tube finished products and the composite carbon-carbon inner layer finished product combination prepared in Examples 1-3 of the present invention is similar to that of the hard felt tube finished products prepared in Comparative Examples 1-3, they are significantly better than Comparative Examples 1-3 in terms of compressive strength and tensile strength. Therefore, the hard felt tube finished products and the composite carbon-carbon inner layer finished product combination prepared in Examples 1-3 of the present invention have higher structural strength, thereby being able to be used stably for a long time and having a longer service life.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite hard felt thermal field material for a high pressure gas quenching furnace, characterized in that: The steps include: Step 1: Prepare the mold required for the production of hard felt tubes according to the model of the high-pressure gas quenching furnace; Step 2: soaking the soft felt with a liquid resin material, and winding the soaked soft felt around the outer periphery of the mold prepared in step 1, and selecting the number of winding layers of the soft felt according to a preset thickness; Step 3: After the soft felt is wound, it is baked and shaped; Step 4: After shaping, the hard felt tube is separated from its mold, and the separated hard felt tube is sent to a graphitization furnace for graphitization treatment; Step 5: The graphitized hard felt cylinder is purified to obtain a finished hard felt cylinder; Step 6: Select the same high pressure gas quenching furnace model as in step 1 to prepare the mold required for the production of the composite carbon-carbon inner layer; Step 7: The outer periphery of the mold prepared in step 6 is wound with glued carbon fiber to a specified thickness, and then shaped and demoulded to perform a densification treatment; Step 8: After the densification treatment is completed, the composite carbon-carbon inner layer is sent to a graphitization furnace for graphitization treatment; Step nine: the graphitized composite carbon-carbon inner layer is purified to obtain a finished composite carbon-carbon inner layer; Step 10: Fix and connect the hard felt tube product obtained in step 5 and the composite carbon-carbon inner layer product obtained in step 9.

2. The method for preparing a composite hard felt thermal field material for a high pressure gas quenching furnace according to claim 1, characterized in that: The mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six are both made of 304 stainless steel. The mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six have welded reinforcing ribs in the middle to facilitate the connection of the internal rotating shaft; the surface roughness of the mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six is ​​lower than 0.8; a layer of PTFE release paper is affixed to the outer surface of the mold required for the production of the hard felt tube in step one and the mold required for the production of the composite carbon-carbon inner layer in step six, and the thickness of the PTFE release paper is 0.5 mm.

3. The method for preparing a composite hard felt thermal field material for a high pressure gas quenching furnace according to claim 1, characterized in that: The liquid resin in step 2 is phenolic resin, and the soft felt is soaked for 10-20 minutes.

4. The method for preparing a composite hard felt thermal field material for a high pressure gas quenching furnace according to claim 1, characterized in that: In the step 2, the soft felt needs to be close to the mold surface during the winding process. After one layer of winding is completed, it needs to be compacted again by a roller. A layer of graphite carbon foil is set between two adjacent layers of soft felt. After all the soft felts are wound, they are placed between the upper mold and the lower mold. The upper mold and the lower mold are fixedly connected on both sides by bolts, so as to further compact the wound soft felt and increase the density. The thickness of the soft felt is 8-10mm, and the thickness of the graphite carbon foil is 0.4-0.6mm.

5. The method for preparing a composite hard felt thermal field material for a high pressure gas quenching furnace according to claim 1, characterized in that: The baking and shaping treatment in the step three includes the following operations: putting the wound soft felt together with the mold into a blast oven, heating it to 60-80°C, heating time for 1 hour, keeping it warm for 30 minutes, then heating it to 80-120°C, heating time for 1 hour, keeping it warm for 1 hour, and finally heating it to 120-240°C, heating time for 3 hours, keeping it warm for 1 hour; after the operation is completed, air cool it to room temperature.

6. The method for preparing a composite hard felt thermal field material for a high pressure gas quenching furnace according to claim 1, characterized in that: The specific operation of the graphitization treatment in step 4 and step 8 is as follows: the shaped hard felt tube or the densified composite carbon-carbon inner layer is sent into the graphitization furnace, and then nitrogen is introduced to maintain an oxygen-free environment, and then the temperature is increased, and the heating rate is controlled at 100-200°C / h, and the temperature is increased to 2200°C, and then the heating is stopped after 18-24h and the nitrogen is kept introduced. After the temperature drops to 100°C, the nitrogen is stopped, and it can be taken out after cooling to room temperature.

7. The method for preparing a composite hard felt thermal field material for a high pressure gas quenching furnace according to claim 1, characterized in that: The specific operation of the purification treatment of the graphitized hard felt tube in step five and the graphitized composite carbon-carbon inner layer in step nine is: soak the graphitized hard felt tube and the graphitized composite carbon-carbon inner layer in a hydrochloric acid solution with a concentration of 5-10%, take them out after soaking, rinse them with clean water for 3-5 times, and then blow dry them with hot air at 60-80°C.

8. The method for preparing a composite hard felt thermal field material for a high pressure gas quenching furnace according to claim 1, characterized in that: The carbon fiber in step seven is T700-12k carbon fiber yarn, the carbon fiber is wound in a hoop or spiral manner, the winding thickness is 3-5mm, and liquid phenolic resin is used for gluing. Before winding, the gluing can be completed by passing through a tank filled with liquid phenolic resin.

9. The method for preparing a composite hard felt thermal field material for a high pressure gas quenching furnace according to claim 1, characterized in that: The specific operation of the densification treatment in step seven is: put the carbon fiber after winding and demolding into a heating furnace, introduce nitrogen to remove the air, then heat it to 1100°C, and then introduce methane gas to keep warm for 2-3 hours, then stop heating and cool to room temperature before taking it out.

10. The method for preparing a composite hard felt thermal field material for a high pressure gas quenching furnace according to claim 1, characterized in that: The methods for fixing and connecting the hard felt tube product obtained in step 5 of the step 10 and the composite carbon-carbon inner layer product obtained in step 9 include: sewing, bolting, and chemical connection.

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