A preparation method of a casting runner pipe

Abstract

The present invention relates to the technical field of refractory materials, and specifically relates to a preparation method of a casting runner pipe, which includes: 1) preparing wet materials; 2) calcining a composite refractory aggregate and modified bauxite, and then blending them with viscose fiber, silicone resin, methyl cellulose and water, and aging for at least one week; 3) extruding the aged mud to form a formed blank, drying it and then sintering it, and cooling it in the furnace to obtain the casting runner pipe. In the present invention, the added composite refractory aggregate has good thermal shock resistance, can inhibit the propagation of cracks and consume residual stress, thereby improving the service performance of the casting runner pipe. Moreover, the added modified bauxite has uniformly sized and regularly arranged ceramic particles formed during sintering, which helps to make the surface structure of the casting runner pipe dense and flat, helps to improve the quality of castings and reduce the rejection rate, so as to better meet the requirements of high-end casting processes.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory materials, and particularly to a preparation method of a casting runner tube. Background Technique

[0002] Refractory materials are basic materials in the thermal engineering field and are widely used in industries such as cement, glass, ceramics, and metal smelting. In steel smelting, in addition to using refractory materials in high-temperature smelting furnaces, a refractory runner tube, usually called a ceramic runner tube or ceramic tube, is also used in casting. This runner tube is actually an intermediate product between refractory materials and ceramics: if it is called a refractory material, it is prepared according to the sintering process of ceramics; if it is called a ceramic, the raw material selection and use completely conform to refractory materials. Therefore, this runner tube is actually a special refractory ceramic runner tube.

[0003] For example, the invention patent with the publication number of CN106216608A discloses a preparation method of a casting runner tube, including: a. batching: adding the qualified silicate fiber, reinforcing material, and binder into a mixer according to a ratio for stirring; b. dilution: adding water to the uniformly stirred combined material at a concentration of eight per thousand for dilution; c. forming: the diluted slurry is formed by a forming machine through the vacuum suction method; d. drying: the wet blank of the formed pipe fitting enters a drying chamber and is dried by high-temperature circulating hot air, and the water is evaporated and dehydrated until the water content is 55-60%; e. shaping: putting the dried pipe fitting blank into a shaping machine mold for high-temperature hot pressing and shaping; f. trimming and inspection: removing the flash of the pipe fitting and inspecting each product one by one; however, in the raw materials of this casting runner tube, some particles are prone to break by themselves and cannot inhibit the propagation of cracks, resulting in poor thermal shock resistance, thus affecting the use performance of the casting runner tube, restricting its application range, and making it unable to meet the requirements of high-end casting processes. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a preparation method of a casting runner tube.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A preparation method of a casting runner tube specifically includes the following steps:

[0007] 1) Preparation of wet materials: The main materials are composed of a composite refractory aggregate, viscose fiber, modified bauxite, and silicone resin, and methyl cellulose and water are also added to the main materials;

[0008] 2) Calcining the composite refractory aggregate and modified bauxite at 1100-1200 °C for 3-6 h, then mixing them with viscose fiber, silicone resin, methyl cellulose, and water, and aging for at least one week;

[0009] 3) The aged clay is extruded into a tube to obtain a formed body, which is then dried and sintered, and then cooled in the furnace to obtain a cast runner tube.

[0010] As a further preferred embodiment of the present invention, in the wet material preparation, the components are calculated by weight as follows: 30-50 parts of composite refractory aggregate, 5-10 parts of viscose fiber, 20-30 parts of modified bauxite, 3-7 parts of silicone resin, 5-8 parts of methyl cellulose, and 10-15 parts of water.

[0011] As a further preferred embodiment of the present invention, in the tube extrusion molding, corresponding molds are used to produce straight tubes, curved tubes, and tees;

[0012] The mold comprises an inner core and male and female opening covers forming the male and female opening shapes of the pipe opening.

[0013] As a further preferred embodiment of the present invention, the sintering temperature is 1280-1350° C., and the sintering time is 3-6 hours.

[0014] As a further preferred embodiment of the present invention, the preparation method of the composite refractory aggregate is as follows:

[0015] 1) dissolving copper nitrate in ethanol and stirring evenly, then slowly adding the solution to phenolic resin, stirring evenly and then curing, placing the cured product in a tube furnace for calcining, and cooling the furnace to obtain a carbide;

[0016] 2) After mixing alumina and carbide, add zirconium oxide, mix well, add to phenolic resin, stir thoroughly, and cure at 110-120° C. for 15-20 hours. After pressurizing the cured product, place it in a tubular furnace for calcination, and cool it to room temperature to obtain a composite refractory material.

[0017] As a further preferred embodiment of the present invention, in step 1), the ratio of copper nitrate to ethanol is (1-3) g: (20-50) mL;

[0018] The mass of the copper nitrate is 1-3wt% of the mass of the phenolic resin;

[0019] The curing operation is: curing at 80-85°C for 12-18 hours, curing at 110-116°C for 12-18 hours, and curing at 180-185°C for 24-28 hours;

[0020] The calcination treatment is performed as follows: in an argon atmosphere, the temperature is raised to 300-350°C at a rate of 5-8°C / min and kept at that temperature for 1-3 hours, and then the temperature is raised to 500-520°C, 600-630°C and 800-850°C at the same rate and kept at that temperature for 3-5 hours respectively.

[0021] As a further preferred embodiment of the present invention, in step 2), the dosage ratios of alumina, carbide, zirconia, and phenolic resin are (20-30) g : (5-10) g : (3-6) g : (100-200) g;

[0022] The operation of the calcination treatment is as follows: in an argon atmosphere, heat up to 400-500 °C at a rate of 5-8 °C / min, and keep warm for 1-3 h, then heat up to 1100-1200 °C at the same rate and keep warm for 5-8 h.

[0023] As a further preferred embodiment of the present invention, the preparation method of the modified bauxite is as follows:

[0024] 1) Slowly add zinc acetate and cobalt acetate to deionized water in sequence. After stirring until fully dissolved, add thiourea, and continue stirring for 30-50 min to obtain a reaction solution. Add carbon fiber to the reaction solution, impregnate for 1-2 h, then transfer to a hydrothermal reaction kettle, seal and perform hydrothermal treatment for 24-30 h. After the reaction ends, cool to room temperature. After centrifuging the product, wash it repeatedly with deionized water and absolute ethanol, and dry it to obtain pretreated carbon fiber;

[0025] 2) Add bauxite, deionized water, and pretreated carbon fiber to a planetary ball mill, mix and grind for 30-50 min, then add sodium dodecyl sulfate, perform ultrasonic emulsification treatment for 20-40 min, and then use a spray dryer to spray-dry the obtained product to obtain modified bauxite.

[0026] As a further preferred embodiment of the present invention, in step 1), the dosage ratios of zinc acetate, cobalt acetate, deionized water, thiourea, and carbon fiber are (3.5-5.0) g : (9.5-13.0) g : (4000-5000) mL : (8.5-11.5) g : (20-30) g;

[0027] The temperature of the hydrothermal treatment is 180-190 °C.

[0028] As a further preferred embodiment of the present invention, in step 2), the dosage ratios of bauxite, deionized water, pretreated carbon fiber, and sodium dodecyl sulfate are (50-65) g : (30-40) mL : (2-5) g : (3-6) g;

[0029] The power of the ultrasonic emulsification is 200-300 W.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] In the present invention, copper nitrate is used as the copper source and introduced into the phenolic resin. When calcined under an argon atmosphere, the reducing gas formed by the pyrolysis of the phenolic resin reduces to elemental copper and releases heat, and can delay the thermal weight loss process of the phenolic resin, increasing the residual carbon rate of the phenolic resin, thereby contributing to an increase in the carbide yield. At the same time, the introduction of copper can increase the graphitization degree of the carbide. As the graphitization degree increases, a layered structure is formed in the carbide, which can impede the propagation of cracks, causing the crack propagation direction to change, thereby consuming the energy of crack propagation and achieving the effect of inhibiting crack propagation, thus reducing the elastic modulus and improving the thermal shock resistance. Moreover, in the carbide, copper catalyzes the carbon source to form carbon nanofibers. As the number of carbon nanofibers increases, they are closely packed in a cluster-like structure, and as the carbon nanofibers grow along the diameter direction, they gradually decrease and finally form a tapered shape. On the one hand, the carbon nanofibers form a network structure through cross-linking, which can effectively transfer and disperse thermal stress, thereby reducing the formation of cracks. On the other hand, they are embedded in the layered structure of the carbide in a tapered shape, playing a supporting role for the layered structure and preventing the layered structure from collapsing, thus contributing to an increase in the stability of the layered structure. By combining the carbide with alumina and zirconia and introducing them into the phenolic resin, a composite refractory aggregate is formed through high-temperature calcination. The carbide can effectively reduce the formation and propagation of cracks. Alumina and zirconia will undergo crystal transformation at high temperatures, resulting in volume expansion, generating residual stress and fine cracks inside the particles. Due to the reduction of the elastic modulus, the thermal shock resistance can be further improved.

[0032] In the present invention, zinc acetate, cobalt acetate, and thiourea are used as the zinc source, cobalt source, and sulfur source respectively, and carbon fiber is used as the deposition matrix. A flower-like nanomaterial is deposited on the carbon fiber through a hydrothermal reaction to obtain pretreated carbon fiber. The pretreated carbon fiber is added to bauxite. The flower-like nanomaterial deposited on the surface of the pretreated carbon fiber serves as a connection node to cross-link and form a framework structure, which can enclose bauxite particles within it, thereby contributing to an increase in the toughness of bauxite and the stability of the structure. Moreover, sodium dodecyl sulfate is added for emulsification treatment to separate and wrap bauxite into independent fine particles, which are dried to form solid bauxite particles, facilitating the demolding treatment after molding. And when sintered, the ceramic particles formed by bauxite are of uniform size and regular arrangement. Due to the high hardness of the ceramic particles and their resistance to cracking, when cracks encounter ceramic particles during the crack propagation path, the high-hardness ceramic particles force the crack propagation path to change from linear propagation to curved propagation, thereby increasing the consumption of crack energy and slowing down the crack propagation. Moreover, the regularly arranged ceramic particles contribute to the denseness and flatness of the surface structure of the casting runner tube, helping to improve the quality of the casting and reduce the rejection rate.

[0033] In the present invention, composite refractory aggregate, viscose fiber, modified bauxite and silicone resin are used as main ingredients, methyl cellulose and water are added, and a casting runner pipe is formed through aging and sintering. The added composite refractory aggregate has good thermal shock resistance, can inhibit the expansion of cracks and consume residual stress, thereby improving the performance of the casting runner pipe. Moreover, the ceramic particles formed by the added modified bauxite during sintering are uniform in size and regularly arranged, which helps to make the surface structure of the casting runner pipe dense and smooth, helps to improve the quality of castings, and reduces the scrap rate, thereby better meeting the needs of high-end casting processes. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solutions in 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 any creative efforts are within the scope of protection of the present invention.

[0035] Example 1

[0036] A method for preparing a cast runner tube specifically comprises the following steps:

[0037] 1) Wet material preparation: The main material is composed of 30 parts of composite refractory aggregate, 5 parts of viscose fiber, 20 parts of modified bauxite, and 3 parts of silicone resin, and 5 parts of methyl cellulose and 10 parts of water are added to the main material;

[0038] 2) calcining the composite refractory aggregate and modified bauxite at 1100°C for 3 hours, then blending with viscose fiber, silicone resin, methyl cellulose, and water, and aging for at least one week;

[0039] 3) The aged clay is used to make straight pipes, curved pipes, and tees using corresponding molds. The molds include an inner core and male and female covers that form the shape of the pipe mouth. The molded body is obtained by extrusion molding, and then sintered after drying. It is sintered at a temperature of 1280°C for 3 hours and cooled in the furnace to obtain a cast runner pipe.

[0040] The preparation method of composite refractory aggregate is as follows:

[0041] 1) Dissolve 1 g of copper nitrate in 20 mL of ethanol and stir evenly. Then slowly add it to the phenolic resin, controlling the mass of copper nitrate to be 1 wt% of the mass of the phenolic resin. After stirring well, cure at 80 °C for 12 h, at 110 °C for 12 h, and at 180 °C for 24 h respectively. Place the cured product in a tube furnace. Under an argon atmosphere, heat it to 300 °C at a rate of 5 °C / min and hold for 1 h. Then heat it to 500 °C, 600 °C, and 800 °C respectively at the same rate and hold for 3 h each. After cooling with the furnace, obtain the carbide;

[0042] 2) Mix 20 g of alumina and 5 g of carbide, then add 3 g of zirconia. After mixing evenly, add it to 100 g of phenolic resin. After stirring well, cure at 110 °C for 15 h. After pressing the cured product into shape, place it in a tube furnace. Under an argon atmosphere, heat it to 400 °C at a rate of 5 °C / min and hold for 1 h. Then heat it to 1000 °C at the same rate and hold for 5 h. Cool to room temperature with the furnace to obtain the composite refractory material.

[0043] Among them, the preparation method of the modified bauxite is as follows:

[0044] 1) Slowly add 3.5 g of zinc acetate and 9.5 g of cobalt acetate to 4000 mL of deionized water in sequence. After stirring until fully dissolved, add 8.5 g of thiourea and continue stirring for 30 min to obtain a reaction solution. Add 20 g of carbon fiber to the reaction solution, impregnate for 1 h, then transfer it to a hydrothermal reaction kettle, seal it, and perform hydrothermal treatment at 180 °C for 24 h. After the reaction ends, cool to room temperature. After centrifuging the product, wash it repeatedly with deionized water and absolute ethanol, and dry it to obtain the pretreated carbon fiber;

[0045] 2) Add 50 g of bauxite, 30 mL of deionized water, and 2 g of pretreated carbon fiber to a planetary ball mill, mix and grind for 30 min. Then add 3 g of sodium dodecyl sulfate and perform ultrasonic emulsification treatment at 200 W for 20 min. Then use a spray dryer to spray-dry the obtained product to obtain the modified bauxite.

[0046] Example 2

[0047] A preparation method of a casting runner tube specifically includes the following steps:

[0048] 1) Wet material preparation: Calculated by weight parts, the main material consists of 40 parts of composite refractory aggregate, 7 parts of viscose fiber, 25 parts of modified bauxite, and 5 parts of silicone resin. 6 parts of methyl cellulose and 12 parts of water are also added to the main material;

[0049] 2) calcining the composite refractory aggregate and modified bauxite at 1150°C for 5 hours, then blending with viscose fiber, silicone resin, methyl cellulose, and water, and aging for at least one week;

[0050] 3) The aged clay is used to make straight pipes, curved pipes and tees using corresponding molds. The molds include an inner core and male and female covers that form the shape of the pipe mouth. The molded body is obtained by extrusion molding, and then sintered after drying. It is sintered at a temperature of 1320°C for 5 hours and cooled in the furnace to obtain a cast runner pipe.

[0051] The preparation method of composite refractory aggregate is as follows:

[0052] 1) 2 g of copper nitrate was dissolved in 35 mL of ethanol and stirred, and then slowly added to a phenolic resin, controlling the mass of the copper nitrate to be 2 wt % of the mass of the phenolic resin. After fully stirring, the mixture was cured at 82° C. for 15 h, 113° C. for 15 h, and 182° C. for 25 h, respectively. The cured product was placed in a tube furnace, heated to 320° C. at a rate of 7° C. / min under an argon atmosphere, and kept warm for 2 h. The temperature was then raised to 510° C., 620° C., and 820° C. at the same rate, and kept warm for 4 h, respectively. The carbide was then cooled in the furnace to obtain a carbide.

[0053] 2) After mixing 25g of alumina and 7g of carbide, add 5g of zirconium oxide, mix well, add to 150g of phenolic resin, stir thoroughly and cure at 115°C for 18h. After the cured product is pressurized and formed, place it in a tubular furnace and heat it to 450°C at a rate of 7°C / min in an argon atmosphere and keep it warm for 2h. Then heat it to 1050°C at the same rate and keep it warm for 7h. Cool it to room temperature with the furnace to obtain a composite refractory material.

[0054] Wherein, the preparation method of modified bauxite is as follows:

[0055] 1) 4.2 g of zinc acetate and 11.5 g of cobalt acetate were slowly added to 4500 mL of deionized water in sequence, stirred until fully dissolved, and then 10 g of thiourea was added. After stirring for 40 min, a reaction solution was obtained. 25 g of carbon fiber was added to the reaction solution, immersed for 1.5 h, and then transferred to a hydrothermal reactor. After sealing, the mixture was hydrothermally treated at 185 ° C for 28 h. After the reaction was completed, it was cooled to room temperature, the product was centrifuged, and then repeatedly washed with deionized water and anhydrous ethanol, and dried to obtain pretreated carbon fiber;

[0056] 2) Add 60 g of bauxite, 35 mL of deionized water, and 3 g of pretreated carbon fiber into a planetary ball mill, mix and grind for 40 min, then add 5 g of sodium dodecyl sulfate, perform ultrasonic emulsification treatment at 250 W for 30 min, and then use a spray dryer to spray-dry the obtained product to obtain modified bauxite.

[0057] Example 3

[0058] A preparation method of a casting runner tube specifically includes the following steps:

[0059] 1) Wet material preparation: Calculated by weight parts, the main material consists of 50 parts of composite refractory aggregate, 10 parts of viscose fiber, 30 parts of modified bauxite, and 7 parts of silicone resin. 8 parts of methyl cellulose and 15 parts of water are also added to the main material;

[0060] 2) Calcinate the composite refractory aggregate and modified bauxite at 1200 °C for 6 h, then blend them with viscose fiber, silicone resin, methyl cellulose, and water, and let them age for at least one week;

[0061] 3) Use the aged mud material to make straight pipes, elbow pipes, and tees with corresponding molds. The molds include an inner core and male and female covers forming the shape of the pipe orifice. After extrusion molding, the formed green body is obtained, dried and then sintered. Sinter at a temperature of 1350 °C for 6 h, and cool with the furnace to obtain the casting runner tube.

[0062] Among them, the preparation method of the composite refractory aggregate is as follows:

[0063] 1) Dissolve 3 g of copper nitrate in 50 mL of ethanol and stir evenly, then slowly add it to phenolic resin, controlling the mass of copper nitrate to be 3 wt% of the mass of phenolic resin. After fully stirring evenly, cure at 85 °C for 18 h, cure at 116 °C for 18 h, and cure at 185 °C for 28 h respectively. Place the cured product in a tubular furnace, under an argon atmosphere, heat it to 350 °C at a rate of 8 °C / min, and hold for 3 h, then heat it to 520 °C, 630 °C, and 850 °C respectively at the same rate, and hold for 5 h respectively. Cool with the furnace to obtain carbide;

[0064] 2) Mix 30 g of alumina and 10 g of carbide, then add 6 g of zirconia, mix evenly, add it to 200 g of phenolic resin, fully stir and cure at 120 °C for 20 h. After pressing the cured product into shape, place it in a tubular furnace, under an argon atmosphere, heat it to 500 °C at a rate of 8 °C / min, and hold for 3 h, then heat it to 1100 °C at the same rate and hold for 8 h. Cool to room temperature with the furnace to obtain the composite refractory material.

[0065] Among them, the preparation method of the modified bauxite is as follows:

[0066] 1) Slowly add 5 g of zinc acetate and 13 g of cobalt acetate to 5000 mL of deionized water in sequence. After stirring until fully dissolved, add 11.5 g of thiourea, continue stirring for 50 min to obtain a reaction solution. Add 30 g of carbon fiber to the reaction solution, immerse it for 2 h, then transfer it to a hydrothermal reaction kettle, seal it, and perform hydrothermal treatment at 190 °C for 30 h. After the reaction ends, cool it to room temperature. Centrifuge the product, wash it repeatedly with deionized water and absolute ethanol, and dry it to obtain pretreated carbon fiber;

[0067] 2) Add 65 g of bauxite, 40 mL of deionized water, and 5 g of pretreated carbon fiber to a planetary ball mill, mix and grind for 50 min, then add 6 g of sodium dodecyl sulfate, perform ultrasonic emulsification treatment at 300 W for 40 min, and then use a spray dryer to spray-dry the obtained product to obtain modified bauxite.

[0068] Comparative Example 1: This comparative example is basically the same as Example 1, except that silica is used to replace the composite refractory aggregate.

[0069] Comparative Example 2: This comparative example is basically the same as Example 1, except that in the preparation of the composite refractory aggregate, step 1) is omitted.

[0070] Comparative Example 3: This comparative example is basically the same as Example 1, except that ordinary bauxite is used to replace the modified bauxite.

[0071] Comparative Example 4: This comparative example is basically the same as Example 1, except that in the preparation of the modified bauxite, step 1) is omitted.

[0072] Comparative Example 5: This comparative example is basically the same as Example 1, except that silica is used to replace the composite refractory aggregate, and ordinary bauxite is used to replace the modified bauxite.

[0073] Test experiment:

[0074] Measure the linear change on reheating at 1400 °C of the specimens provided in Examples 1 - 3 and Comparative Examples 1 - 5 respectively according to the method of GB / T5988 - 2004, and the results are shown in Table 1.

[0075] Table 1

[0076]

[0077] It can be seen from Table 1 that the casting runner tube in the present invention has small shrinkage at high temperature and excellent thermal shock resistance, which greatly improves the performance of the casting runner tube, so as to better meet the requirements of high-end casting processes.

[0078] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A preparation method of a casting runner pipe, characterized in that Specifically, it includes the following steps: 1) Preparation of wet materials: Calculated by weight parts, the main materials are composed of 30 - 50 parts of composite refractory aggregate, 5 - 10 parts of viscose fiber, 20 - 30 parts of modified bauxite, and 3 - 7 parts of silicone resin. In the main materials, 5 - 8 parts of methyl cellulose and 10 - 15 parts of water are also added. The preparation method of the composite refractory aggregate is as follows: ① Dissolve copper nitrate in ethanol and stir evenly. The dosage ratio of copper nitrate to ethanol is (1 - 3) g : (20 - 50) mL. Then slowly add it to phenolic resin. The mass of copper nitrate is 1 - 3 wt% of the mass of phenolic resin. After fully stirring evenly, cure at 80 - 85 °C for 12 - 18 h, cure at 110 - 116 °C for 12 - 18 h, and cure at 180 - 185 °C for 24 - 28 h. Place the cured product in a tube furnace for calcination, that is, under an argon atmosphere, heat up to 300 - 350 °C at a rate of 5 - 8 °C / min and keep it warm for 1 - 3 h. Then heat up to 500 - 520 °C, 600 - 630 °C, and 800 - 850 °C at the same rate respectively, and keep them warm for 3 - 5 h and then cool with the furnace to obtain carbide; ② After mixing alumina and carbide, then add zirconia. After mixing evenly, add it to phenolic resin. After fully stirring, cure at 110 - 120 °C for 15 - 20 h. After pressing the cured product into shape, place it in a tube furnace for calcination, that is, under an argon atmosphere, heat up to 400 - 500 °C at a rate of 5 - 8 °C / min and keep it warm for 1 - 3 h. Then heat up to 1100 - 1200 °C at the same rate and keep it warm for 5 - 8 h. Cool to room temperature with the furnace to obtain the composite refractory aggregate. Among them, the dosage ratio of alumina, carbide, zirconia, and phenolic resin is (20 - 30) g : (5 - 10) g : (3 - 6) g : (100 - 200) g; 2) Calcinate the composite refractory aggregate and modified bauxite at 1100 - 1200 °C for 3 - 6 h, then blend them with viscose fiber, silicone resin, methyl cellulose, and water, and let them age for at least one week; 3) Extrude the aged mud through a pipe to obtain a formed blank, dry it and then sinter it, and cool with the furnace to obtain a casting runner pipe.

2. The preparation method of a casting runner tube according to claim 1, characterized in that, In the pipe extrusion molding, straight pipes, bent pipes, and tees are made with corresponding molds; The mold includes a core and male and female covers forming the shape of the pipe orifice; 3. The preparation method of a casting runner pipe according to claim 1, characterized in that, The sintering temperature is 1280 - 1350 °C, and the sintering time is 3 - 6 h.

4. The preparation method of a casting runner tube according to claim 1, characterized in that, The preparation method of the modified bauxite is as follows: 1) Slowly add zinc acetate and cobalt acetate to deionized water in sequence. After stirring until fully dissolved, add thiourea, and continue to stir for 30 - 50 min to obtain a reaction solution. Add carbon fiber to the reaction solution, impregnate for 1 - 2 h, then transfer it to a hydrothermal reaction kettle, seal it and perform hydrothermal treatment for 24 - 30 h. After the reaction ends, cool to room temperature. After centrifugally separating the product, wash it repeatedly with deionized water and absolute ethanol, and dry it to obtain pretreated carbon fiber; 2) Add bauxite, deionized water, and pretreated carbon fiber into a planetary ball mill, mix and grind for 30 - 50 min, then add sodium dodecyl sulfate, perform ultrasonic emulsification treatment for 20 - 40 min, and then use a spray dryer to spray-dry the obtained product to obtain modified bauxite.

5. The preparation method of a casting runner pipe according to claim 4, characterized in that, In step 1), the dosage ratio of zinc acetate, cobalt acetate, deionized water, thiourea, and carbon fiber is (3.5 - 5.0) g : (9.5 - 13.0) g : (4000 - 5000) mL : (8.5 - 11.5) g : (20 - 30) g; The temperature of the hydrothermal treatment is 180 - 190 °C.

6. The preparation method of a casting runner pipe according to claim 4, characterized in that, In step 2), the dosage ratio of bauxite, deionized water, pretreated carbon fiber, and sodium dodecyl sulfate is (50 - 65) g : (30 - 40) mL : (2 - 5) g : (3 - 6) g; The power of the ultrasonic emulsification is 200 - 300 W.

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