A cast heat-retaining and heat-generating patch material and a method for manufacturing the same

Abstract

The present application relates to the technical field of casting materials, in particular to a heat preservation and heating patch material for casting and a preparation method thereof, which comprises a composite heating material, high-aluminum vitrified microbeads, high-purity quartz sand, phenolic resin, a curing agent and a silane coupling agent. The present application mainly solves the feeding requirements of complex parts and positions where risers cannot be set, overcomes the process limitations of conventional manufacturers, and custom-produces shape-following heating blocks. The product closely fits the shape of the casting, has no gaps after pouring, and has a smooth surface without the need for secondary processing. The shape-following heating block is made of special heating material, has extremely high refractoriness, does not produce excess gas during heating, and the heat can be adjusted at will according to the needs of the casting, greatly improving the process yield, reducing the use of risers and cold irons, and providing a solution to compensate for casting defects for casting enterprises.

Description

Technical Field

[0001] This invention relates to the field of casting materials technology, specifically to a heat-insulating and heating patch material for casting and its preparation method. Background Technology

[0002] Casting is a method of pouring molten metal into a casting cavity that conforms to the shape of the part, and then allowing it to cool and solidify to obtain the part or blank. With the rapid development of science and technology, various devices and equipment are constantly emerging. In the process of production casting, the problem of varying sizes of the required castings is often encountered. During the forming process, due to the difference in size, the larger areas of the molten steel solidify more slowly during cooling, making them prone to defects such as shrinkage cavities and porosity. This seriously affects the quality of the casting and makes it unable to meet market demands.

[0003] For example, the invention patent with announcement number CN115283621A discloses a heating pad for castings, its preparation method, and its application. The heating pad includes, by material mass percentage: 22%-27% heating agent, 20%-25% thermal insulation material, 18%-23% refractory aggregate, 20%-25% binder, 3.5%-4.5% combustion aid, and 3%-4% oxidant. This heating pad for castings meets the shrinkage requirements of castings. After casting and molding, the heating pad falls off on its own, making it easy to clean and significantly reducing the workload of subsequent blank cleaning and machining. However, since the heating agent in the heating pad is directly mixed with other raw materials, prolonged high-temperature environments during use can easily cause the heating agent to migrate within the heating pad. This leads to the heating agent in the heating pad easily migrating to the material surface and falling off, resulting in a limited service life for the heating pad material, which cannot be reused multiple times. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a heat-insulating and heating patch material for casting and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A casting insulation and heating pad material comprises a composite heating material, high-alumina vitrified microspheres, high-purity quartz sand, phenolic resin, a curing agent, and a silane coupling agent. By weight, the composite heating material comprises 80-120 parts, the high-alumina vitrified microspheres comprise 5-10 parts, the high-purity quartz sand comprises 15-30 parts, the phenolic resin comprises 5-10% of the total weight of the composite heating material and the high-purity quartz sand, the curing agent comprises 20-28% of the phenolic resin, and the silane coupling agent comprises 1-3% of the phenolic resin.

[0007] As a further preferred embodiment of the present invention, the preparation method of the composite heating material is as follows:

[0008] 1) Add ferric nitrate, ammonium fluoride and urea to deionized water, stir and dissolve at room temperature to obtain a mixture, then pour it into a hydrothermal reactor, add nickel nitrate and mix evenly, seal and react at 120-130℃ for 6-10h. After the reaction is completed, wash the product with deionized water and dry it to obtain the precursor product.

[0009] 2) Add sodium sulfide to deionized water, stir and dissolve at room temperature, pour into a hydrothermal reactor, add the precursor product, seal and react at 100-110℃ for 8-12 hours. After the reaction is completed, wash the product with deionized water and dry to obtain flower-shaped nanoparticles.

[0010] 3) Add the heating agent to deionized water and ultrasonically disperse it evenly to obtain a dispersion. Immerse the porous carbon fiber cloth material in the dispersion, transfer it to a vacuum impregnation tank, evacuate it to 50-100Pa, and impregnate it for 30-50 minutes under ultrasonic action of 100-200W. Slowly depressurize it to normal pressure and repeat the operation 2-5 times. After drying, the pretreated carbon fiber cloth material is obtained.

[0011] 4) Disperse the flower-shaped nanoparticles ultrasonically in deionized water, then immerse the pretreated carbon fiber cloth material in it, and transfer it to a vacuum impregnation tank. Evacuate to 10-50 Pa and impregnate for 40-70 min under ultrasonic action of 200-300 W. Slowly depressurize to normal pressure and repeat the operation 2-5 times. After drying, cut to obtain the composite heating material.

[0012] As a further preferred embodiment of the present invention, the ratio of the amounts of ferric nitrate, ammonium fluoride, urea, deionized water and nickel nitrate is (1-3)g:(0.2-0.4)g:(0.7-0.9)g:(50-80)mL:(0.5-1.2)g.

[0013] As a further preferred embodiment of the present invention, the ratio of sodium sulfide, deionized water and precursor product is (2-4)g:(50-80)mL:(1-2)g.

[0014] As a further preferred embodiment of the present invention, the heating agent is composed of aluminum powder, potassium nitrate and hollow microspheres in a mass ratio of 1:(1-2):(2-4);

[0015] The ratio of the heating agent, deionized water, and porous carbon fiber cloth material is (6-10)g:(80-120)mL:(5-10)g;

[0016] As a further preferred embodiment of the present invention, the ratio of the flower-shaped nanoparticles, deionized water, and pretreated carbon fiber cloth material is (3-8)g:(100-150)mL:(10-18)g.

[0017] As a further preferred embodiment of the present invention, the method for preparing the porous carbon fiber cloth material is as follows:

[0018] 1) Place polyacrylonitrile powder in N,N-dimethylformamide and stir magnetically at 60-65℃ for 2-5 hours. After the solution becomes clear, add diphenylmethane diisocyanate dropwise and continue stirring at a constant temperature for 1-2 hours. Then, sonicate for 10-30 minutes and obtain the spinning solution after degassing.

[0019] 2) Transfer the spinning solution into the syringe, spin at a speed of 18-23 mm / min, use distilled water as the coagulation bath, and keep the distance between the syringe and the roller at 70-90 cm. Spin the fiber material on the roller at a speed of 15-30 r / min. After sonicating the fiber material for 20-40 min, let it stand in distilled water until no more bubbles are produced. Then, dry it in an oven at 60-70℃ to remove moisture and obtain hollow foamed fiber material.

[0020] 3) Place the hollow foamed fiber material in an oven, first heat it from room temperature to 160-180℃ and keep it at that temperature for 1-3 hours, then raise the temperature to 220-240℃ and keep it at that temperature for 1-3 hours, and finally raise the temperature to 270-280℃ and keep it at that temperature for 1-3 hours. Then cool it down to room temperature to obtain pre-oxidized hollow foamed fiber material. Then immerse it in potassium hydroxide aqueous solution and soak it at 95-100℃ for 3-7 hours. After washing and drying, transfer it to a high-temperature tube furnace, introduce high-purity nitrogen gas, heat it from room temperature to 800-860℃ and keep it at that temperature for 1-3 hours. After cooling it down to room temperature, weave it to obtain porous carbon fiber cloth material.

[0021] As a further preferred embodiment of the present invention, the proportion of polyacrylonitrile powder, N,N-dimethylformamide, and diphenylmethane diisocyanate in the spinning solution is (3-6)g:(60-100)mL:(2-5)g.

[0022] As a further preferred embodiment of the present invention, the heating rate in the oven is 3-5℃ / min;

[0023] The concentration of the potassium hydroxide aqueous solution is 2-3 mol / L;

[0024] In the high-temperature tubular furnace, the heating rate is 5-10℃ / min.

[0025] A method for preparing a heat-insulating and heating patch material for casting specifically includes the following steps:

[0026] The weighed composite heating material, high-alumina vitrified microspheres, high-purity quartz sand, phenolic resin, curing agent and silane coupling agent are mixed and stirred in a sand mixer for 3-8 minutes. After stirring evenly, the mixture is added to the pre-made core box, compacted, and then left to stand for 10-20 minutes to cure and form.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] In this invention, diphenylmethane diisocyanate, a foaming agent, is mixed into a solution of polyacrylonitrile and N,N-dimethylformamide. Wet spinning is performed using water as a coagulation bath. The chemical reaction between diphenylmethane diisocyanate and water generates carbon dioxide, creating pores within the polyacrylonitrile fibers to obtain a hollow foamed fiber material. After high-temperature oxidation, it undergoes potassium hydroxide activation treatment. Potassium hydroxide has a certain etching effect on the carbon fibers, increasing the volume of micropores. Following high-temperature carbonization and weaving, a porous carbon fiber cloth material is obtained. This carbon fiber cloth material has a rich porous structure, with many interconnected pores, providing ample storage space for the subsequent loading of the heating agent. Then, a heating agent, a mixture of aluminum powder, potassium nitrate, and hollow microspheres, is infiltrated into the pore structure of the porous carbon fiber cloth material using vacuum impregnation. To improve the loading rate of the porous carbon fiber cloth material, ultrasonic treatment is performed during vacuum impregnation. Under the action of ultrasound, the penetration of the heating agent into the pore structure of the porous carbon fiber cloth material is accelerated, thereby... This method can significantly improve the load rate. Simultaneously, potassium nitrate in the heating agent acts as an oxygen source, releasing oxygen under high-temperature conditions. The aluminum powder reacts with the released oxygen, continuously heating the contact area of ​​the heating agent. Furthermore, to ensure the released heat is not quickly dissipated, hollow microspheres store some of the heat, further improving the sustainability of the heat supply. Moreover, to prevent the heating agent from leaking out, this invention uses ferric nitrate and sodium sulfide as iron and sulfur sources, and nickel nitrate as a nickel source. Flower-shaped nanoparticles are synthesized via a hydrothermal method. Then, through vacuum impregnation and ultrasonic assistance, the flower-shaped nanoparticles are infiltrated into the pore structure of the porous carbon fiber cloth. Since the pore structure has already been filled with a large amount of heating agent, the nanoparticles are mainly distributed at the pore openings. Due to their numerous convex petal-like structures, these structures can be better embedded at the pore openings, and through mutual stacking and interlocking, the openings are sealed, thus confining the heating agent within the pores and effectively preventing its migration and loss under high-temperature conditions, thereby contributing to improved heating agent stability.

[0029] In this invention, a composite heating material is obtained by firmly confining the heating agent within a porous carbon fiber cloth material. This composite material is then added to the heating pad material, which helps improve the stability of the heating agent and ensures a sufficient heat source. This keeps the molten steel in the casting in contact with the heating pad in a liquid state, facilitating the riser to fill defective areas and improve the quality of the finished casting. Simultaneously, it prevents the heating agent from migrating to the material surface and falling off under prolonged high temperatures, thus extending the service life of the heating pad material and enabling multiple reuses, thereby improving its performance. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] In this embodiment of the invention, the curing agent is hexamethylenetetramine, and the silane coupling agent is vinyltrimethoxysilane.

[0032] Example 1

[0033] A casting insulation and heating pad material includes a composite heating material, high-alumina vitrified microspheres, high-purity quartz sand, phenolic resin, curing agent and silane coupling agent;

[0034] The composite heating material comprises 80 parts by weight, the high-alumina vitrified microspheres comprise 5 parts by weight, the high-purity quartz sand comprises 15 parts by weight, the phenolic resin comprises 5% of the total weight of the composite heating material and the high-purity quartz sand, the curing agent comprises 20% of the phenolic resin, and the silane coupling agent comprises 1% of the phenolic resin.

[0035] The preparation method of this fever-reducing patch material specifically includes the following steps:

[0036] The weighed composite heating material, high-alumina vitrified microspheres, high-purity quartz sand, phenolic resin, curing agent and silane coupling agent are mixed and stirred in a sand mixer for 3 minutes. After stirring evenly, the mixture is added to the pre-made core box, compacted, and then left to stand for 10 minutes to cure and form.

[0037] The preparation method of the composite heating material is as follows:

[0038] 1) Place 3g of polyacrylonitrile powder in 60mL of N,N-dimethylformamide and stir magnetically at 60℃ for 2h. After the solution becomes clear, add 2g of diphenylmethane diisocyanate and continue stirring at a constant temperature for 1h. Then, sonicate at 200W for 10min and obtain the spinning solution after degassing.

[0039] 2) Transfer the spinning solution into the syringe, the spinning speed is 18 mm / min, distilled water is used as the coagulation bath, the distance from the syringe to the roller is 70 cm, the spun fiber material is placed on the roller at a speed of 15 r / min, the obtained fiber material is ultrasonicated at 100 W for 20 min, then placed in distilled water to stand until no more bubbles are produced, and then placed in a 60℃ oven to dry and remove moisture to obtain hollow foamed fiber material;

[0040] 3) The hollow foamed fiber material is placed in an oven and heated from room temperature to 160°C at a heating rate of 3°C / min, held for 1 hour, then heated to 220°C and held for 1 hour, and finally heated to 270°C and held for 1 hour. After cooling to room temperature, a pre-oxidized hollow foamed fiber material is obtained. Then, it is immersed in a 2 mol / L potassium hydroxide aqueous solution and soaked at 95°C for 3 hours. After washing and drying, it is transferred to a high-temperature tube furnace, high-purity nitrogen is introduced, and the heating rate is 5°C / min. It is heated from room temperature to 800°C and held for 1 hour. After cooling to room temperature, it is woven to obtain a porous carbon fiber cloth material.

[0041] 4) Add 1g of ferric nitrate, 0.2g of ammonium fluoride and 0.7g of urea to 50mL of deionized water, stir and dissolve at room temperature to obtain a mixture, then pour it into a hydrothermal reactor, add 0.5g of nickel nitrate and mix well, seal and react at 120℃ for 6h. After the reaction is completed, wash the product with deionized water and dry it to obtain the precursor product.

[0042] 5) Add 2g of sodium sulfide to 50mL of deionized water, stir and dissolve at room temperature, pour into a hydrothermal reactor, add 1g of precursor product, seal and react at 100℃ for 8h. After the reaction is complete, wash the product with deionized water and dry to obtain flower-shaped nanoparticles.

[0043] 6) Add 6g of the heating agent, which is a mixture of aluminum powder, potassium nitrate and hollow microspheres in a mass ratio of 1:1:2, to 80mL of deionized water and ultrasonically disperse it evenly to obtain a dispersion. Immerse 5g of porous carbon fiber cloth material in the dispersion, transfer it to a vacuum impregnation tank, evacuate to 50Pa, and impregnate it for 30min under 100W ultrasonic action. Slowly depressurize it to normal pressure and repeat the operation twice. After drying, the pretreated carbon fiber cloth material is obtained.

[0044] 7) Disperse 3g of flower-shaped nanoparticles ultrasonically in 100mL of deionized water, then immerse 10g of pretreated carbon fiber cloth material in it, and transfer it to a vacuum impregnation tank. Evacuate to 10Pa and impregnate for 40min under 200W ultrasonic action. Slowly depressurize to normal pressure and repeat the operation twice. After drying, cut to obtain composite heating material.

[0045] Example 2

[0046] A casting insulation and heating pad material includes a composite heating material, high-alumina vitrified microspheres, high-purity quartz sand, phenolic resin, curing agent and silane coupling agent;

[0047] The composite heating material comprises 100 parts by weight, the high-alumina vitrified microspheres comprise 8 parts by weight, the high-purity quartz sand comprises 25 parts by weight, the phenolic resin comprises 7% of the total weight of the composite heating material and the high-purity quartz sand, the curing agent comprises 25% of the phenolic resin, and the silane coupling agent comprises 2% of the phenolic resin.

[0048] The preparation method of this fever-reducing patch material specifically includes the following steps:

[0049] The weighed composite heating material, high-alumina vitrified microspheres, high-purity quartz sand, phenolic resin, curing agent and silane coupling agent are mixed and stirred in a sand mixer for 5 minutes. After stirring evenly, the mixture is added to the pre-made core box, compacted, and then left to stand for 15 minutes to cure and form.

[0050] The preparation method of the composite heating material is as follows:

[0051] 1) Place 5g of polyacrylonitrile powder in 80mL of N,N-dimethylformamide and stir magnetically at 63℃ for 3h. After the solution becomes clear, add 3g of diphenylmethane diisocyanate and continue stirring at a constant temperature for 1.5h. Then, sonicate at 250W for 20min and obtain the spinning solution after degassing.

[0052] 2) Transfer the spinning solution into the syringe, the spinning speed is 20 mm / min, distilled water is used as the coagulation bath, the distance from the syringe to the roller is 80 cm, the spun fiber material is placed on the roller at a speed of 25 r / min, the obtained fiber material is ultrasonicated at 150 W for 30 min, then placed in distilled water to stand until no more bubbles are produced, and then placed in a 65℃ oven to dry and remove moisture to obtain hollow foamed fiber material;

[0053] 3) The hollow foamed fiber material is placed in an oven and heated from room temperature to 170°C at a heating rate of 4°C / min, held for 2 hours, then heated to 230°C and held for 2 hours, and finally heated to 275°C and held for 2 hours. After cooling to room temperature, a pre-oxidized hollow foamed fiber material is obtained. Then, it is immersed in a 2.5 mol / L potassium hydroxide aqueous solution and soaked at 98°C for 5 hours. After washing and drying, it is transferred to a high-temperature tube furnace, high-purity nitrogen is introduced, and the heating rate is 7°C / min. It is heated from room temperature to 850°C and held for 2 hours. After cooling to room temperature, it is woven to obtain a porous carbon fiber cloth material.

[0054] 4) Add 2g of ferric nitrate, 0.3g of ammonium fluoride and 0.8g of urea to 70mL of deionized water, stir and dissolve at room temperature to obtain a mixture, then pour it into a hydrothermal reactor, add 1g of nickel nitrate and mix well, seal and react at 125℃ for 8h. After the reaction is completed, wash the product with deionized water and dry it to obtain the precursor product.

[0055] 5) Add 3g of sodium sulfide to 70mL of deionized water, stir and dissolve at room temperature, pour into a hydrothermal reactor, add 1.5g of precursor product, seal and react at 105℃ for 10h. After the reaction is complete, wash the product with deionized water and dry to obtain flower-shaped nanoparticles.

[0056] 6) Add 80g of the heating agent, which is a mixture of aluminum powder, potassium nitrate and hollow microspheres in a mass ratio of 1:1.5:3, to 100mL of deionized water and ultrasonically disperse it evenly to obtain a dispersion. Immerse 7g of porous carbon fiber cloth material into the dispersion, transfer it to a vacuum impregnation tank, evacuate it to 80Pa, and impregnate it for 40min under ultrasonic action of 150W. Slowly depressurize it to normal pressure, repeat the operation 3 times, and dry it to obtain the pretreated carbon fiber cloth material.

[0057] 7) Disperse 5g of flower-shaped nanoparticles ultrasonically in 130mL of deionized water, then immerse 15g of pretreated carbon fiber cloth material in it, and transfer it to a vacuum impregnation tank. Evacuate to 30Pa and impregnate for 60min under 250W ultrasonic action. Slowly depressurize to normal pressure and repeat the operation 3 times. After drying, cut to obtain composite heating material.

[0058] Example 3

[0059] A casting insulation and heating pad material includes a composite heating material, high-alumina vitrified microspheres, high-purity quartz sand, phenolic resin, curing agent and silane coupling agent;

[0060] The composite heating material comprises 120 parts by weight, the high-alumina vitrified microspheres comprise 10 parts by weight, the high-purity quartz sand comprises 30 parts by weight, the phenolic resin comprises 10% of the total weight of the composite heating material and the high-purity quartz sand, the curing agent comprises 28% of the phenolic resin, and the silane coupling agent comprises 3% of the phenolic resin.

[0061] The preparation method of this fever-reducing patch material specifically includes the following steps:

[0062] The weighed composite heating material, high-alumina vitrified microspheres, high-purity quartz sand, phenolic resin, curing agent and silane coupling agent are mixed and stirred in a sand mixer for 8 minutes. After stirring evenly, the mixture is added to the pre-made core box, compacted, and then left to stand for 20 minutes to cure and form.

[0063] The preparation method of the composite heating material is as follows:

[0064] 1) Place 6g of polyacrylonitrile powder in 100mL of N,N-dimethylformamide and stir magnetically at 65℃ for 5h. After the solution becomes clear, add 5g of diphenylmethane diisocyanate and continue stirring at a constant temperature for 2h. Then, sonicate at 300W for 30min and obtain the spinning solution after degassing.

[0065] 2) Transfer the spinning solution into the syringe, the spinning speed is 23 mm / min, distilled water is used as the coagulation bath, the distance from the syringe to the roller is 90 cm, the spun fiber material is placed on the roller at a speed of 30 r / min, the obtained fiber material is ultrasonicated at 200 W for 40 min, then placed in distilled water to stand until no more bubbles are produced, and then placed in a 70℃ oven to dry and remove moisture to obtain hollow foamed fiber material;

[0066] 3) The hollow foamed fiber material is placed in an oven and heated from room temperature to 180°C at a heating rate of 5°C / min, and held for 3 hours. Then it is heated to 240°C and held for 3 hours. Finally, it is heated to 280°C and held for 3 hours. Then it is cooled to room temperature to obtain pre-oxidized hollow foamed fiber material. Then it is immersed in 3 mol / L potassium hydroxide aqueous solution and soaked at 100°C for 7 hours. After washing and drying, it is transferred to a high-temperature tube furnace, high-purity nitrogen is introduced, and the heating rate is 10°C / min. It is heated from room temperature to 860°C and held for 3 hours. After cooling to room temperature, it is woven to obtain porous carbon fiber cloth material.

[0067] 4) Add 3g of ferric nitrate, 0.4g of ammonium fluoride and 0.9g of urea to 80mL of deionized water, stir and dissolve at room temperature to obtain a mixture, then pour it into a hydrothermal reactor, add 1.2g of nickel nitrate and mix well, seal and react at 130℃ for 10h. After the reaction is completed, wash the product with deionized water and dry it to obtain the precursor product.

[0068] 5) Add 4g of sodium sulfide to 80mL of deionized water, stir and dissolve at room temperature, pour into a hydrothermal reactor, add 2g of precursor product, seal and react at 110℃ for 12h. After the reaction is completed, wash the product with deionized water and dry to obtain flower-shaped nanoparticles.

[0069] 6) Add 10g of the heating agent, which is a mixture of aluminum powder, potassium nitrate and hollow microspheres in a mass ratio of 1:2:4, to 120mL of deionized water and ultrasonically disperse it evenly to obtain a dispersion. Immerse 10g of porous carbon fiber cloth material in the dispersion, transfer it to a vacuum impregnation tank, evacuate it to 100Pa, and impregnate it for 50min under the action of 200W ultrasound. Slowly depressurize it to normal pressure and repeat the operation 5 times. After drying, the pretreated carbon fiber cloth material is obtained.

[0070] 7) Disperse 8g of flower-shaped nanoparticles ultrasonically in 150mL of deionized water, then immerse 18g of pretreated carbon fiber cloth material in it, and transfer it to a vacuum impregnation tank. Evacuate to 50Pa and impregnate for 70min under 300W ultrasonic action. Slowly depressurize to normal pressure and repeat the operation 5 times. After drying, cut to obtain composite heating material.

[0071] Comparative Example 1: This comparative example is basically the same as Example 1, except that a heating agent (composed of aluminum powder, potassium nitrate and hollow microspheres) is used instead of the composite heating material.

[0072] Comparative Example 2: This comparative example is basically the same as Example 1, except that the potassium hydroxide aqueous solution in step 3) is omitted in the preparation of the composite heating material.

[0073] Comparative Example 3: This comparative example is basically the same as Example 1, except that steps 4)-5) are omitted in the preparation of the composite heating material.

[0074] Comparative Example 4: This comparative example is basically the same as Example 1, except that the ultrasonic treatment in step 6) is omitted in the preparation of the composite heating material.

[0075] Comparative Example 5: This comparative example is basically the same as Example 1, except that the ultrasonic treatment in step 7) is omitted in the preparation of the composite heating material.

[0076] Test experiment:

[0077] Using the process methods provided in Examples 1-3 and Comparative Examples 1-5, samples of heating pad material were prepared and then applied to production. The castings after casting were compared, and the yield rate of the castings was recorded. The results are shown in Table 1.

[0078] Table 1

[0079] Yield % 82.1 83.6 82.7 60.4 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Yield % 69.2 65.8 71.6 72.5

[0080] As shown in Table 1, the heating pad material in this invention can effectively improve the quality of finished castings, increase the yield rate, reduce machining workload and time, and reduce the overall production cost of castings.

[0081] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A casting heat-insulating and heating pad material, characterized in that, The product comprises a composite heating material, high-alumina vitrified microspheres, high-purity quartz sand, phenolic resin, a curing agent, and a silane coupling agent. By weight, the composite heating material comprises 80-120 parts, the high-alumina vitrified microspheres comprise 5-10 parts, the high-purity quartz sand comprises 15-30 parts, the phenolic resin comprises 5-10% of the total weight of the composite heating material and the high-purity quartz sand, the curing agent comprises 20-28% of the phenolic resin, and the silane coupling agent comprises 1-3% of the phenolic resin. The preparation method of the composite heating material is as follows: 1) Add ferric nitrate, ammonium fluoride and urea to deionized water, stir and dissolve at room temperature to obtain a mixture, then pour it into a hydrothermal reactor, add nickel nitrate and mix evenly, seal and react at 120-130℃ for 6-10h. After the reaction is completed, wash the product with deionized water and dry it to obtain the precursor product. 2) Add sodium sulfide to deionized water, stir and dissolve at room temperature, pour into a hydrothermal reactor, add the precursor product, seal and react at 100-110℃ for 8-12 hours. After the reaction is completed, wash the product with deionized water and dry to obtain flower-shaped nanoparticles. 3) Add the heating agent to deionized water and ultrasonically disperse it evenly to obtain a dispersion. Immerse the porous carbon fiber cloth material in the dispersion, transfer it to a vacuum impregnation tank, evacuate it to 50-100Pa, and impregnate it for 30-50 minutes under ultrasonic action of 100-200W. Slowly depressurize it to normal pressure and repeat the operation 2-5 times. After drying, the pretreated carbon fiber cloth material is obtained. 4) Disperse the flower-shaped nanoparticles ultrasonically in deionized water, then immerse the pretreated carbon fiber cloth material in it, and transfer it to a vacuum impregnation tank. Evacuate to 10-50 Pa and impregnate for 40-70 min under ultrasonic action of 200-300 W. Slowly depressurize to normal pressure and repeat the operation 2-5 times. After drying, cut to obtain the composite heating material.

2. The heat-insulating and heating pad material for casting according to claim 1, characterized in that, In step 1), the ratio of the amounts of ferric nitrate, ammonium fluoride, urea, deionized water and nickel nitrate is (1-3)g: (0.2-0.4)g: (0.7-0.9)g: (50-80)mL: (0.5-1.2)g.

3. The heat-insulating and heating pad material for casting according to claim 1, characterized in that, In step 2), the ratio of sodium sulfide, deionized water, and precursor product is (2-4) g: (50-80) mL: (1-2) g.

4. The heat-insulating and heating pad material for casting according to claim 1, characterized in that, The heating agent is composed of aluminum powder, potassium nitrate and hollow microspheres in a mass ratio of 1:(1-2):(2-4); In step 3), the ratio of the amount of the heating agent, deionized water and porous carbon fiber cloth material is (6-10)g: (80-120)mL: (5-10)g.

5. The heat-insulating and heating pad material for casting according to claim 1, characterized in that, In step 4), the ratio of the amount of flower-shaped nanoparticles, deionized water, and pretreated carbon fiber cloth material is (3-8) g: (100-150) mL: (10-18) g.

6. The heat-insulating and heating pad material for casting according to claim 1, characterized in that, The preparation method of the porous carbon fiber cloth material is as follows: 1) Place polyacrylonitrile powder in N,N-dimethylformamide and stir magnetically at 60-65℃ for 2-5 hours. After the solution becomes clear, add diphenylmethane diisocyanate dropwise and continue stirring at a constant temperature for 1-2 hours. Then, sonicate for 10-30 minutes and obtain the spinning solution after degassing. 2) Transfer the spinning solution into the syringe, spin at a speed of 18-23 mm / min, use distilled water as the coagulation bath, and keep the distance between the syringe and the roller at 70-90 cm. Spin the fiber material on the roller at a speed of 15-30 r / min. After sonicating the fiber material for 20-40 min, let it stand in distilled water until no more bubbles are produced. Then, dry it in an oven at 60-70℃ to remove moisture and obtain hollow foamed fiber material. 3) Place the hollow foamed fiber material in an oven, first heat it from room temperature to 160-180℃ and keep it at that temperature for 1-3 hours, then raise the temperature to 220-240℃ and keep it at that temperature for 1-3 hours, and finally raise the temperature to 270-280℃ and keep it at that temperature for 1-3 hours. Then cool it down to room temperature to obtain pre-oxidized hollow foamed fiber material. Then immerse it in potassium hydroxide aqueous solution and soak it at 95-100℃ for 3-7 hours. After washing and drying, transfer it to a high-temperature tube furnace, introduce high-purity nitrogen gas, heat it from room temperature to 800-860℃ and keep it at that temperature for 1-3 hours. After cooling it down to room temperature, weave it to obtain porous carbon fiber cloth material.

7. The heat-insulating and heating pad material for casting according to claim 6, characterized in that, In the spinning solution, the ratio of polyacrylonitrile powder, N,N-dimethylformamide, and diphenylmethane diisocyanate is (3-6) g: (60-100) mL: (2-5) g.

8. The heat-insulating and heating pad material for casting according to claim 6, characterized in that, In the oven, the heating rate is 3-5℃ / min; The concentration of the potassium hydroxide aqueous solution is 2-3 mol / L; In the high-temperature tubular furnace, the heating rate is 5-10℃ / min.

9. A method for preparing a casting heat-insulating and heating patch material according to any one of claims 1-8, characterized in that, Specifically, the steps include the following: The weighed composite heating material, high-alumina vitrified microspheres, high-purity quartz sand, phenolic resin, curing agent and silane coupling agent are mixed and stirred in a sand mixer for 3-8 minutes. After stirring evenly, the mixture is added to the pre-made core box, compacted, and then left to stand for 10-20 minutes to cure and form.