CN112692966B - Thin-wall silicon carbide pipe anti-deformation extrusion molding process and special anti-deformation support - Google Patents
Thin-wall silicon carbide pipe anti-deformation extrusion molding process and special anti-deformation support Download PDFInfo
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Abstract
An anti-deforming extrusion technology for thin-wall silicon carbide pipe features that the binding agent and shaping agent are optimized to increase the solid content of premixed material and create the structure-activity relation between structure and performance, and the extrusion method is used to prepare the heat-transfer silicon carbide pipe with wall thickness delta (1.8-2.4 mm) and external diameter phi (16.5-22.5 mm) instead of imported one. The anti-deformation support is arranged at the front end of the extrusion equipment and used for receiving the extruded silicon carbide pipe, the support rod can be pushed to move to one side after the pipe is cut off, and the next support rod is moved to enable the empty support groove to be aligned to the extrusion equipment, so that the next operation is carried out, and the operation is convenient. The height of the lifting seat can be adjusted so as to be convenient for being matched with extrusion equipment with different heights; the bolt connecting part of the bracket is assembled in the threaded hole of the supporting rod, and the height of the bracket can be adjusted, so that the supporting groove can be conveniently leveled; the air-dry mechanism is arranged on the upper part of the supporting seat, and air-dries the silicon carbide to speed up the shaping and prevent the deformation.
Description
Technical Field
The invention relates to the technical field of silicon carbide pipe processing, in particular to an anti-deformation extrusion molding process for a thin-wall silicon carbide pipe.
Background
The heat exchanger is widely used as heat exchange equipment widely used in chemical industry, oil refining, power, food, light industry, atomic energy, pharmacy, machinery and other industrial departments. In chemical production, the heat exchanger is used as a heater, a cooler, an evaporator, a condenser, a reboiler and the like, and has the main functions of realizing heat exchange and transfer in the production process and ensuring the specific temperature required by the process for a medium. In a chemical plant, the investment of heat exchange equipment accounts for about 10-20% of the total investment; in refineries, it accounts for about 35% to 40% of the total investment. However, if a failure accident occurs, a series of serious consequences such as casualties, direct economic loss, indirect loss, environmental pollution and the like can occur. In particular, a heat transfer element, namely a heat exchange tube, is a key part in the heat exchanger, which is directly contacted with materials, and is very easy to fail due to corrosion leakage after being exposed to a severe working environment for a long time. Therefore, the research and development of the novel material heat transfer element have important significance for promoting economic development and guaranteeing the life and property safety of people in the practical engineering.
The existing heat exchangers have the following types: the steel-based heat exchanger is low in price and easy to process, occupies most of the market share of the heat exchanger, but cannot be dealt with when encountering corrosive media. Graphite is easily oxidized, and has limited pressure resistance, temperature resistance or corrosion resistance, and low heat conduction efficiency. Rare metals: cost performance remains a major disadvantage for tantalum, zirconium and hafnium alloys. Therefore, a heat exchanger made of corrosion-resistant, high-temperature-resistant and pressure-resistant materials is urgently needed to solve the heat conversion task under special working conditions.
The silicon carbide heat exchanger is a device which is formed by combining an element made of pressureless sintered silicon carbide material with an element made of other materials. The silicon carbide material has excellent heat conductivity, corrosion resistance and high temperature resistance, and especially has incomparable advantages of other materials under the heat exchange working condition of a strong corrosion medium. Therefore, if a silicon carbide heat exchanger could be introduced to replace some of the fluoroplastic and precious metal heat exchange applications, the economic benefits would be very great.
The core technology for manufacturing the silicon carbide heat exchanger is the preparation of a silicon carbide heat transfer element-SiC heat exchange tube, a plate and a connecting part. In order to improve the heat exchange efficiency, the tube wall of the SiC heat exchange tube is required to be as thin as possible on the premise of ensuring the quality performance. At present, the thin-wall thin and long heat transfer element of silicon carbide is easy to have the defects of bending, cracking and the like during production, the rejection rate of products is high, and the heat resistance of the thin-wall silicon carbide and the connecting parts is still not well solved, so that the silicon carbide heat exchanger in China mainly depends on import.
Disclosure of Invention
The invention aims to solve the technical problem of providing an anti-deformation extrusion molding process and a special anti-deformation support for a thin-wall silicon carbide pipe, which solve the bottleneck problem of the preparation of a thin-wall silicon carbide ceramic heat transfer element by optimizing a bonding agent and a shaping agent, improving the solid content of a premix and establishing the structure-activity relationship between the structure and the performance of a product, and adopts an extrusion molding method to prepare the silicon carbide heat transfer pipe with the wall thickness delta being 1.5-2mm and the outer diameter phi being 14-19mm to replace the inlet.
The invention provides a deformation-preventing extrusion molding process for a thin-wall silicon carbide pipe, which comprises the following steps of:
(1) preparing materials: weighing silicon carbide powder, hydroxypropyl methyl cellulose and a carbon source, respectively pouring the silicon carbide powder, the hydroxypropyl methyl cellulose and the carbon source into a stirring pot, and stirring to completely melt the hydroxypropyl methyl cellulose and the carbon source into the silicon carbide powder to obtain mixed powder A; weighing boron carbide, adding the boron carbide into the degreasing agent, and uniformly stirring and dispersing to obtain a boron carbide mixed solution B;
(2) mixing materials: adding the mixed powder A into a cement mortar stirrer for stirring, slowly adding the boron carbide mixed solution B into a stirring pot after uniformly stirring, simultaneously adding a lubricant into the stirring pot, stirring for 30min, packaging with a plastic film, placing in a shade, and standing for 24h to obtain a mixed material C;
(3) and (3) refining mud: cleaning and starting the mud refining machine, slowly adding the mixture C into the mud refining machine after the mud refining machine starts to rotate, discarding crushed materials at the front section of the mud refining machine until no crushed materials are extruded out, putting the refined silicon carbide rod into the mud refining machine for repeatedly refining mud, and dividing the refined silicon carbide mixture into a plurality of sections after the silicon carbide rod is refined for a plurality of times to obtain the silicon carbide rod;
(4) and (3) extrusion molding: adding a silicon carbide rod into an extruder, extruding to form a silicon carbide pipe blank with the wall thickness delta of 1.8-2.4mm and the outer diameter phi of 16.5-22.5mm, placing the silicon carbide pipe blank on an anti-deformation support, and airing;
(5) and (3) sintering: placing the dried silicon carbide pipe blank in a high-temperature vacuum furnace for sintering to obtain a silicon carbide pipe, wherein the sintering process is divided into five stages:
the first stage is as follows: the room temperature is 200 ℃, and the heating rate is 10 ℃/min;
and a second stage: the temperature is raised at the rate of 5 ℃/min to be 200-800 ℃, and the temperature is preserved for 15min at 800 ℃;
and a third stage: the temperature is 800-1800 ℃, and the heating rate is 10 ℃/min;
a fourth stage: 1800-2150 ℃, the heating rate is 5 ℃/min, and the temperature is preserved for 30min at 2150 ℃;
the fifth stage: stopping heating, and naturally cooling to room temperature along with the furnace.
Preferably, the degreasing agent is acetone.
Preferably, the lubricant is a mixture of oleic/tung oil and glycerol.
Preferably, the addition amount of each ingredient is as follows according to the weight portion: 100 parts of SiC, 3-7 parts of HPMC (hydroxy propyl methyl cellulose), 3-8 parts of oleic acid/tung oil, 1-5 parts of glycerol and B41-3 parts of C, 1-2 parts of C, 1-3 parts of acetone and a proper amount of water.
Preferably, the addition amount of each ingredient is as follows according to the weight portion: the addition amount of each ingredient is as follows according to the weight portion: 100 parts of SiC, 4.5 parts of HPMC (hydroxy propyl methyl cellulose), 5 parts of oleic acid/tung oil, 2 parts of glycerol and B4C1 part, C1 part and acetone 2 parts.
Preferably, the extrusion speed in the step (4) is 1-3 m/min.
Preferably, the stirring speed in the step (2) is 100-300 r/min.
The invention also discloses a special anti-deformation support for extrusion molding of the thin-wall silicon carbide pipe, which comprises a lifting seat, a movable support frame and an air drying mechanism, wherein:
the lifting seat comprises a base, and a lifting support is vertically arranged on the base;
the movable support frame comprises a rectangular support arranged at the upper end of the lifting support, at least one group of guide rails is arranged on the rectangular support, a plurality of groups of sliding blocks are arranged in each group of guide rails, each group of sliding blocks is connected with a support rod, a group of supports are arranged on each support rod, and a support groove is arranged on each group of supports;
the air drying mechanism comprises an air drying support, a fan and a heater, the air drying mechanism is arranged above the movable support frame, an air outlet pipe is arranged on the air drying support, an air outlet nozzle is arranged on the air outlet pipe, the air outlet pipe is communicated with a heater air outlet through an air supply pipe, and a heater air inlet is communicated with a fan air outlet.
Preferably, the support rod is provided with a threaded hole, the bracket comprises a support part and a bolt connecting part connected to the lower side of the support part, and the bolt connecting part is connected in the threaded hole; the supporting groove is U-shaped/V-shaped/arc-shaped.
Preferably, the lifting support comprises a fixed rod fixedly connected to the base, a telescopic rod is arranged in the fixed rod, and a fastening bolt is arranged on the fixed rod.
The invention discloses an anti-deformation extrusion molding process of a thin-wall silicon carbide pipe, which is mainly prepared from silicon carbide powder, is added with hydroxypropyl methyl cellulose, a carbon source and boron carbide for modification, is added with acetone as a degreasing agent, and is added with a mixture of oleic acid/tung oil and glycerol as a lubricant. The invention utilizes hydroxypropyl methylcellulose, which is mainly used as a binder with good viscosity, and is also a water retention agent, an emulsifier and a dispersant. The hydroxypropyl methyl cellulose can be adsorbed on an oil-water two-phase interface in the emulsion, so that the interfacial tension is effectively reduced, the property of the emulsifier is shown, a stronger net structure can be formed in the ceramic slurry, the viscosity of the ceramic slurry is increased, and the high-viscosity slurry has a smooth surface appearance. The change process of the hydroxypropyl methyl cellulose in the sintering process is as follows: hydroxypropyl methyl cellulose pyrolysis, organic silicon-like intermediate formation, and carborundum formation and further decomposition into silicon dioxide and carbon, and then the carborundum is formed through a carbothermic reduction mechanism, and the like, so that the formed carborundum pipe has the advantages of fine and smooth surface, compact structure, small sintering shrinkage, difficult deformation, difficult bending and regular shape. The process solves the bottleneck problem of the preparation of the thin-wall silicon carbide ceramic heat transfer element by optimizing a bonding agent and a shaping agent, improving the solid content of the premix and establishing the structure-activity relationship between the structure and the performance of the product, and adopts an extrusion forming method to prepare the silicon carbide heat transfer pipe with the wall thickness delta being 1.5-2mm and the outer diameter phi being 14-19mm to replace the import.
According to the invention, silicon carbide granulation powder and hydroxypropyl methyl cellulose with the viscosity of 4000mPa & s are mixed according to the weight ratio of 100: 4.5, the density of the silicon carbide pipe is remarkably improved by preparing the silicon carbide pipe through a five-step sintering process, and the density value of the silicon carbide pipe is 3.14g/cm3. The sintering process is divided into five stages:
the first stage is as follows: the room temperature is 200 ℃, and the heating rate is 10 ℃/min; through rapid heating up, the water can be volatilized rapidly, HPMC and silicon carbide are fully infiltrated and tightened, a strong net structure is formed in the materials inside the tube culture, the density is increased, and the deformation is prevented.
And a second stage: the temperature is increased at the speed of 5 ℃/min to 200-800 ℃, the temperature is kept at 800 ℃ for 15min, HPMC is rapidly decomposed, simultaneously acetone is thermally degreased, other inorganic additives and residual carbon after organic matters are decomposed are discharged in a gas form, a little C and micropores exist after acetone is degreased and sintered, the micropores are uniformly distributed integrally, the sizes of the pores are about 1um, and the pressure maintaining time is properly prolonged in a secondary temperature interval to ensure the density and prevent deformation;
and a third stage: the temperature is raised at the speed of 10 ℃/min to 800-1800 ℃, and the temperature is raised rapidly in the stage, so that intermediate products are prevented from being generated;
a fourth stage: 1800-2150 ℃, the heating rate is 5 ℃/min, the temperature is kept at 2150 ℃ for 30min, and in the stage, through high-temperature heat-preservation sintering, the diffusion coefficient is increased through increasing the temperature, and the crystal lattices of Si and C are rapidly diffused at high temperature to form a complete silicon carbide crystal structure;
the fifth stage: stopping heating, naturally cooling to room temperature along with the furnace, and slowly cooling at the stage to prevent the pipe fittings from deforming.
According to the special anti-deformation support for extrusion molding of the thin-wall silicon carbide pipe, the anti-deformation support is arranged at the front end of the extrusion equipment, the height of the supporting groove is adjusted by adjusting the lifting support, so that the supporting groove is aligned with and receives the silicon carbide pipe, after each pipe is cut off, the supporting rod is pushed to enable the sliding block to move to one side along the guide rail, and the next supporting rod is moved to enable the empty supporting groove to be aligned with the extrusion equipment, so that the next operation is performed, and the operation is convenient. The height of the lifting seat can be adjusted so as to be convenient for being matched with extrusion equipment with different heights; the bolt connecting part of the bracket is assembled in the threaded hole of the supporting rod, and the height of the bracket can be adjusted, so that the supporting groove can be conveniently leveled; the air-dry mechanism is arranged on the upper part of the supporting seat, and air-dries the silicon carbide to speed up the shaping and prevent the deformation.
Drawings
FIG. 1 is a schematic structural diagram of a deformation-preventing bracket specially used for extrusion molding of thin-wall silicon carbide pipes;
FIG. 2 is an enlarged view of a portion of the mobile support of FIG. 1;
FIG. 3 shows a scanning electron microscope with 1000 times magnification on the section of the thin-walled silicon carbide tube prepared by the invention;
FIG. 4 shows the scanning electron microscope with 3000 times magnification on the section of the thin-wall silicon carbide tube prepared by the invention.
In the figure: the lifting seat 1, the base 11, the lifting support 12, the fixing rod 121, the telescopic rod 122, the fastening bolt 123, the universal wheel 13, the movable support frame 2, the rectangular support 21, the guide rail 22, the sliding block 23, the supporting rod 24, the support 25, the supporting part 251, the bolt connecting part 252, the supporting groove 26, the air drying mechanism 3, the air drying support 31, the fan 32, the heater 33, the air outlet pipe 34, the air outlet nozzle 35 and the air supply pipe 36.
Detailed Description
In order to make the technical scheme of the invention easier to understand, the technical scheme of the invention is clearly and completely described by adopting a mode of a specific embodiment in combination with the attached drawings.
Example 1:
the thin-wall silicon carbide pipe deformation-preventing extrusion molding process comprises the following steps:
(1) preparing materials: weighing silicon carbide powder, hydroxypropyl methyl cellulose and a carbon source, respectively pouring the silicon carbide powder, the hydroxypropyl methyl cellulose and the carbon source into a stirring pot, and stirring to completely melt the hydroxypropyl methyl cellulose and the carbon source into the silicon carbide powder to obtain mixed powder A; weighing boron carbide, adding the boron carbide into the degreasing agent, and uniformly stirring and dispersing to obtain a boron carbide mixed solution B;
(2) mixing materials: adding the mixed powder A into a cement mortar stirrer for stirring, slowly adding the boron carbide mixed solution B into a stirring pot after uniformly stirring, simultaneously adding a lubricant into the stirring pot, stirring for 30min, packaging with a plastic film, placing in a shade, and standing for 24h to obtain a mixed material C; the stirring speed is 100-300 r/min.
(3) And (3) refining mud: cleaning and starting the mud refining machine, slowly adding the mixture C into the mud refining machine after the mud refining machine starts to rotate, discarding crushed materials at the front section of the mud refining machine until no crushed materials are extruded out, putting the refined silicon carbide rod into the mud refining machine for repeatedly refining mud, and dividing the refined silicon carbide mixture into a plurality of sections after the silicon carbide rod is refined for a plurality of times to obtain the silicon carbide rod;
(4) and (3) extrusion molding: adding a silicon carbide rod into an extruder, extruding and forming a silicon carbide pipe blank with the wall thickness delta of 1.8-2.4mm and the outer diameter phi of 16.5-22.5mm, placing the silicon carbide pipe blank on an anti-deformation support, and airing; the extrusion speed is 1-3 m/min.
(5) And (3) sintering: placing the dried silicon carbide pipe blank in a high-temperature vacuum furnace for sintering to obtain a silicon carbide pipe, wherein the sintering process is divided into five stages:
the first stage is as follows: the room temperature is 200 ℃, and the heating rate is 10 ℃/min;
and a second stage: the temperature is raised at the rate of 5 ℃/min to be 200-800 ℃, and the temperature is preserved for 15min at 800 ℃;
and a third stage: the temperature is 800-1800 ℃, and the heating rate is 10 ℃/min;
a fourth stage: 1800-2150 ℃, the heating rate is 5 ℃/min, and the temperature is preserved for 30min at 2150 ℃;
the fifth stage: stopping heating, and naturally cooling to room temperature along with the furnace.
The degreasing agent is acetone, the lubricant is a mixture of oleic acid/tung oil and glycerol, and the addition amount of the ingredients is as follows by weight: 100 parts of SiC, 4.5 parts of HPMC (hydroxy propyl methyl cellulose), 5 parts of oleic acid/tung oil, 3 parts of glycerol and B4C2 parts, C1 parts, acetone 2 parts and a proper amount of water.
Example 2:
the thin-wall silicon carbide pipe deformation-preventing extrusion molding process comprises the following steps:
the difference between the embodiment and the embodiment 1 is that the addition amount of each ingredient is as follows according to the parts by weight: 100 parts of SiC, 3 parts of HPMC, 8 parts of oleic acid/tung oil, 1 part of glycerol and B4C3 parts, C1 parts, acetone 3 parts and a proper amount of water.
Example 3:
the thin-wall silicon carbide pipe deformation-preventing extrusion molding process comprises the following steps:
the difference between the embodiment and the embodiment 1 is that the addition amount of each ingredient is as follows according to the parts by weight: 100 parts of SiC, 7 parts of HPMC, 3 parts of oleic acid/tung oil, 5 parts of glycerol and B4C1 part, C2 part, acetone 1 part and a proper amount of water.
The experimental results show that: HPMC (viscosity: 4000 mPas) with low molecular weight has good mixing and mud-mixing effects in the ceramic tube preparation process, is easy to extrude and form, and has a sintering effect meeting experimental requirements, while HPMC (viscosity: 15000 mPas) with high molecular weight has great influence on the ceramic tube preparation process, so that good mud cannot be obtained during mud-mixing, and extrusion and forming cannot be carried out. The ceramic tube which has a good mud effect and is formed by extruding HPMC with viscosity of 4000 mPa.s in a mud refining process has high hardness and good heat conductivity and meets the use requirement, and the mud material which meets the pipe extrusion can not be refined due to overlarge viscosity in the process of adding HPMC with high viscosity in the mud refining process. The experimental result shows that the higher the viscosity of the HPMC added in the formula, the higher the influence on the fluidity of the material, and the higher the influence on the preparation process of the ceramic tube, and the quality of the prepared ceramic tube is the most excellent when the viscosity is 4000mPa & s.
HPMC with viscosity of 4000mPa & s is selected, sintering density of thin-wall silicon carbide tubes with different HPMC contents is determined, and comparison analysis is carried out in table 1 to obtain: the density of the HPMC with the viscosity of 4000 mPas is increased along with the increase of the density after dry pressing, cold pressing and sintering, wherein the density of a sample piece is the best when the HPMC content is 4.5 weight parts per 100 weight parts of silicon carbide, and the value is 3.14g/cm3. The sintered density of the sample wafer without adding HPMC is 2.873g/cm3However, the press molding is difficult, and the dry-pressed sample piece is easily crushed.
Table 1: HPMC (viscosity: 4000Pa s)
The appearance of the section of the thin-wall silicon carbide pipe prepared by the method is observed by a scanning electron microscope, as can be seen from fig. 3 and 4, the whole distribution of the holes of the sample after degreasing and sintering by adopting acetone is relatively uniform, a little C and holes exist, the sizes of the holes of the sample are about 1um, the compactness is good, and the whole structure is not subjected to bending deformation.
Example 4:
as shown in fig. 1 and 2, the special anti-deformation support for thin-wall silicon carbide pipe extrusion molding of the embodiment comprises a lifting seat 1, a movable support frame 2 and an air drying mechanism 3, wherein:
the lifting seat 1 comprises a base 11, and a lifting support 12 is vertically arranged on the base 11;
the movable support frame 2 comprises a rectangular support 21 arranged at the upper end of the lifting support 12, at least one group of guide rails 22 is arranged on the rectangular support 21, a plurality of groups of sliding blocks 23 are arranged in each group of guide rails 22, each group of sliding blocks 23 is connected with one support rod 24, each support rod 24 is provided with one group of supports 25, and each group of supports 25 is provided with one support groove 26;
air-dry mechanism 3 including air-drying support 31, fan 32 and heater 33, air-dry mechanism 3 locates and removes 2 tops of support frame, air-dry and be equipped with out tuber pipe 34 on the support 31, be equipped with air outlet 35 on the play tuber pipe 34, go out tuber pipe 34 with through blast pipe 36 and heater 33 air outlet intercommunication, heater 33 air intake and fan 32 air outlet intercommunication.
The support rod 24 is provided with a threaded hole, the bracket 25 comprises a support part 251 and a bolt connecting part 252 connected to the lower side of the support part 251, and the bolt connecting part 252 is connected in the threaded hole; the support groove 26 is U-shaped/V-shaped/arc-shaped.
The lifting support 12 comprises a fixing rod 121 fixedly connected to the base 11, a telescopic rod 122 is arranged in the fixing rod 121, and a fastening bolt 123 is arranged on the fixing rod 121.
It should be noted that the embodiments described herein are only some embodiments of the present invention, and not all implementations of the present invention, and the embodiments are only examples, which are only used to provide a more intuitive and clear understanding of the present invention, and are not intended to limit the technical solutions of the present invention. All other embodiments, as well as other simple substitutions and various changes to the technical solutions of the present invention, which can be made by those skilled in the art without inventive work, are within the scope of the present invention without departing from the spirit of the present invention.
Claims (7)
1. An anti-deformation extrusion molding process for a thin-wall silicon carbide pipe is characterized by comprising the following steps:
(1) preparing materials: weighing silicon carbide powder, hydroxypropyl methyl cellulose and a carbon source, respectively pouring the silicon carbide powder, the hydroxypropyl methyl cellulose and the carbon source into a stirring pot, and stirring to completely melt the hydroxypropyl methyl cellulose and the carbon source into the silicon carbide powder to obtain mixed powder A; weighing boron carbide, adding the boron carbide into the degreasing agent, and uniformly stirring and dispersing to obtain a boron carbide mixed solution B;
(2) mixing materials: adding the mixed powder A into a cement mortar stirrer for stirring, slowly adding the boron carbide mixed solution B into a stirring pot after uniformly stirring, simultaneously adding a lubricant into the stirring pot, stirring for 30min, packaging with a plastic film, placing in a shade, and standing for 24h to obtain a mixed material C;
(3) and (3) refining mud: cleaning and starting the mud refining machine, slowly adding the mixture C into the mud refining machine after the mud refining machine starts to rotate, discarding crushed materials at the front section of the mud refining machine until no crushed materials are extruded out, putting the refined silicon carbide rod into the mud refining machine for repeatedly refining mud, and dividing the refined silicon carbide mixture into a plurality of sections after the silicon carbide rod is refined for a plurality of times to obtain the silicon carbide rod;
(4) and (3) extrusion molding: adding a silicon carbide rod into an extruder, extruding to form a silicon carbide pipe blank with the wall thickness delta of 1.8-2.4mm and the outer diameter phi of 16.5-22.5mm, placing the silicon carbide pipe blank on an anti-deformation support, and airing;
(5) and (3) sintering: placing the dried silicon carbide pipe blank in a high-temperature vacuum furnace for sintering to obtain a silicon carbide pipe, wherein the sintering process is divided into five stages:
the first stage is as follows: the room temperature is 200 ℃, and the heating rate is 10 ℃/min;
and a second stage: the temperature is raised at the rate of 5 ℃/min to be 200-800 ℃, and the temperature is preserved for 15min at 800 ℃;
and a third stage: the temperature is 800-1800 ℃, and the heating rate is 10 ℃/min;
a fourth stage: 1800-2150 ℃, the heating rate is 5 ℃/min, and the temperature is preserved for 30min at 2150 ℃;
the fifth stage: stopping heating, and naturally cooling to room temperature along with the furnace.
2. The thin-walled silicon carbide tube deformation-preventing extrusion molding process according to claim 1, wherein the degreasing agent is acetone.
3. The thin-walled silicon carbide tube deformation-resistant extrusion molding process according to claim 1, wherein the lubricant is a mixture of oleic acid/tung oil and glycerol.
4. The deformation-preventing extrusion molding process of the thin-wall silicon carbide pipe as claimed in claim 2 or 3, wherein the addition amount of each ingredient is as follows by weight: 100 parts of SiC, 3-7 parts of HPMC (hydroxy propyl methyl cellulose), 3-8 parts of oleic acid/tung oil, 1-5 parts of glycerol and B41-3 parts of C, 1-2 parts of C, 1-3 parts of acetone and a proper amount of water.
5. The thin-walled silicon carbide tube deformation-preventing extrusion molding process according to claim 4, wherein the addition amount of each ingredient is determined according to the weight of the ingredientsThe weight portions are as follows: 100 parts of SiC, 4.5 parts of HPMC (hydroxy propyl methyl cellulose), 5 parts of oleic acid/tung oil, 2 parts of glycerol and B4C1 part, C1 part and acetone 2 parts.
6. The thin-wall silicon carbide pipe deformation-preventing extrusion molding process according to claim 1, wherein the extrusion speed in the step (4) is 1-3 m/min.
7. The thin-wall silicon carbide pipe deformation-preventing extrusion molding process according to claim 1, wherein the stirring speed in the step (2) is 100-300 r/min.
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