Silicon carbide heating element and production process

Abstract

The present invention belongs to the technical field of the production of silicon carbide electrothermal elements, and particularly relates to silicon carbide heating elements and a production process. The production process of the silicon carbide heating element described in the present invention includes the following steps: (1) Pretreatment of silicon carbide raw materials: Mix the silicon carbide raw materials with additives and perform pre-firing treatment; (2) Mixing and forming: Mix the silicon carbide raw materials with the pretreated silicon carbide, graphite electrode powder, carbon black, and binder, and extrude and form to obtain a rod blank; (3) Drying: Dry the rod blank; (4) First firing: Fire in a carbon tube furnace or a vacuum furnace; (5) Second firing: Fire in a carbon tube furnace or a vacuum furnace to obtain a silicon carbide heating element. The production process of the silicon carbide heating element provided by the present invention is environmentally friendly, and the produced heating element has a high density and adjustable resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of the production of silicon carbide electrothermal elements, and particularly relates to silicon carbide rod heating elements and production processes. Background Art

[0002] The silicon carbide rod is a non-metallic electrothermal element mainly composed of high-purity silicon carbide, which consists of a heating part and a cold end part. The performance of the heating part is crucial. When the silicon carbide rod is in use, the heating part is located inside the furnace chamber, generating heat (converting electrical energy into thermal energy), and its resistance conforms to JB / T3890-2017. The cold end part is located inside the furnace hole and has a relatively small resistance value. In the production process of the heating part of the silicon carbide rod, there are currently mainly two different preparation processes, namely Process A and Process B, each having its own unique advantages and limitations.

[0003] Process A uses asphalt as a binder. After mixing raw materials such as silicon carbide and graphite electrode powder evenly, a rod blank is formed by hot extrusion. The formed rod blank needs to be cooled with cold water to fix its shape and structure. Subsequently, it also needs to be subjected to green firing at a high temperature of about 1000 °C and subsequent firing or roasting processes to ensure that the density and strength of the rod blank meet the usage requirements. This process can manufacture silicon carbide rods with a density of more than 2.55 g / cm³, having high mechanical strength and good thermal conductivity. However, Process A will generate a large amount of polluting gases during the production process, such as soot and harmful gases generated by the combustion of asphalt, which causes serious pollution to the environment and does not meet the increasingly strict environmental protection requirements. In addition, the resistance value adjustment range of Process A is relatively limited, and it is difficult to produce products with high resistance values. For example, although this process can improve the density to a certain extent as disclosed in Patent CN116041077A, it still cannot completely break through the limitations of Process A itself.

[0004] Compared with Process A, Process B adopts a more environmentally friendly preparation method. It uses a small amount of cellulose and PVA as temporary binders, takes silicon carbide as the main raw material, and conducts cold extrusion molding to make a rod blank. The rod blank only needs to be dried at a low temperature not exceeding 200 °C to remove the moisture and volatiles therein. Subsequently, it is subjected to a primary recrystallization firing at a high temperature to bond the particles of the rod blank and further improve the strength. Process B not only avoids the pollution problems generated in Process A, but also improves the controllability of the resistance and the red heat uniformity of the silicon carbide rod prepared. CN105837217A discloses a silicon carbide rod and its preparation method, including a heating element, which is made of the following raw materials by mass fraction: 97% - 98.7% of silicon carbide, 1% - 3% of binder, and 0.1% - 0.3% of boron nitride. The forming method of the heating part adopts extrusion molding. However, since the silicon carbide in the ratio accounts for more than 97%, there is a problem of large friction between the blank and the die barrel, die nozzle and die needle. If the pressure is increased to make the density reach 2.55 g / cm 3 Above, the blank has no fluidity, and it is difficult to extrude. Even when the pressure is too high, the die and equipment will be damaged, and it is impossible to make a high-density heating element. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the above deficiencies existing in the prior art, and provide a production process for a silicon carbide rod heating element, which is environmentally friendly, and the produced heating element has a high density and adjustable resistance.

[0006] The production process of the silicon carbide rod heating element described in the present invention includes the following steps:

[0007] (1) Pretreatment of silicon carbide raw materials: Mix the silicon carbide raw materials with additives and conduct pre-burning treatment;

[0008] (2) Mixing and forming: Mix the unpretreated silicon carbide raw materials with the pretreated silicon carbide, graphite electrode powder, carbon black, and binder, and conduct extrusion molding to obtain a rod blank;

[0009] (3) Drying: Dry the rod blank;

[0010] (4) Primary firing: Fire in a carbon tube furnace or a vacuum furnace;

[0011] (5) Secondary firing: Fire in a carbon tube furnace or a vacuum furnace to obtain a silicon carbide rod heating element.

[0012] The additive in step (1) is boron nitride or boron carbide, and its added mass is 0.5 - 6‰ of the silicon carbide raw materials to be pretreated, and the purity of the silicon carbide is above 99%.

[0013] The pre-sintering in step (1) is carried out at 1900 - 1950 °C for 1 - 1.5 h in a vacuum furnace, or at 2000 - 2100 °C for 1.0 - 1.5 h in a carbon tube furnace under an Ar gas atmosphere.

[0014] In step (2), the mass percentages of the un-pretreated silicon carbide raw material, the pre-treated silicon carbide, graphite electrode powder, carbon black, and binder are 80% - 90% for silicon carbide, 6% - 15% for graphite electrode powder, 0.5% - 1.0% for carbon black, and 3.5% - 4% for binder.

[0015] In step (2), the mass percentage of the un-pretreated silicon carbide raw material to the pre-treated silicon carbide is 55% - 65%:35% - 45%.

[0016] The binder is obtained by mixing cellulose and polyvinyl alcohol in a mass ratio of 7:3 - 5:5.

[0017] The particle size of the graphite electrode powder is 1.5 - 3.5 μm, and the carbon content is ≥99.9%; the specific surface area of the carbon black is 1000 - 2000 m 2 / g, the specific gravity is 1.9 - 2.0 g / cm³, and the carbon content is ≥99%.

[0018] In step (3), the drying temperature is 170 - 190 °C and the time is 8 - 10 h.

[0019] In step (4), the firing temperature in the carbon tube furnace is 2150 - 2200 °C and the firing time is 2 - 3 h; or the firing temperature in the vacuum furnace is 1650 - 1700 °C and the firing time is 8 - 10 h.

[0020] In step (5), the firing temperature in the carbon tube furnace is 2460 - 2480 °C and the firing time is 2.5 - 3.0 h; or the firing temperature in the vacuum furnace is 2180 - 2200 °C and the firing time is 2.0 - 2.5 h.

[0021] Specifically, the production process of the silicon carbide rod heating element includes the following steps:

[0022] (1) Pretreatment of silicon carbide raw material: Mix 35% - 45% of the silicon carbide raw material with 0.5 - 6‰ of boron nitride or boron carbide, and treat it at 1900 - 1950 °C for 1 - 1.5 h in a vacuum furnace, or at 2000 - 2100 °C for 1.0 - 1.5 h in a carbon tube furnace under an Ar gas atmosphere.

[0023] (2) Mixing and forming: Mix the remaining 55% - 65% of the un-pretreated silicon carbide raw material, 35% - 45% of the silicon carbide pre-treated in step (1), a total of 80% - 90%, 6% - 15% of graphite electrode powder, 0.5% - 1.0% of carbon black, and 3.5% - 4% of binder, add water, and cold extrude with a hydraulic press to form a rod blank;

[0024] The binder is obtained by mixing cellulose and polyvinyl alcohol in a mass ratio of 7:3 to 5:5.

[0025] (3)Drying: The rod blanks are dried at 170 - 190 °C for 8 - 10 h.

[0026] (4)Primary firing: The dried rod blanks are covered with silicon particles for silicification (the mass ratio of rod blanks to silicon particles is 100:43 - 100:66), and are placed in a carbon tube furnace protected by an atmosphere (Ar or N2) for firing at a temperature of 2150 - 2200 °C for 2 - 3 h; or fired in a vacuum furnace at a temperature of 1650 - 1700 °C for 8 - 10 h. After firing, the residues adhering to the rod body are cleaned and ground off.

[0027] (5)Secondary firing: The rod blanks after the primary firing in step (4) are covered with 10% - 15% of the mass of the rod blanks of graphite electrode powder, and continue to be fired in a carbon tube furnace at a temperature of 2460 - 2480 °C for 2.5 - 3.0 h; or fired in a vacuum furnace at a temperature of 2180 - 2200 °C for 2.0 - 2.5 h to obtain the silicon carbide rod heating element, meeting the requirements of Annex C in JB / T3890 - 2017.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1)For the production process of the silicon carbide rod heating element of the present invention, the cellulose / PVA environmental protection binder is used to replace asphalt, eliminating high-temperature pollution emissions, reducing drying energy consumption, and having no harmful gases in the production process, meeting environmental protection requirements.

[0030] (2)For the production process of the silicon carbide rod heating element of the present invention, the electrical conductivity of the silicon carbide material is changed through pretreatment to increase the resistance value of this part of the silicon carbide, and combined with the gradient ratio of the untreated material, wide-range regulation of the resistivity of the heating element is achieved (meeting the requirements of Annex C in JB / T3890 - 2017).

[0031] (3)For the production process of the silicon carbide rod heating element of the present invention, the carbon in the green body is converted into new silicon carbide during the primary firing to increase the total content of silicon carbide, and the component composition of the product is further purified through the secondary firing process to improve the recrystallization process. The double firing constructs a high-density framework for the product, with high density and good stability. Specific embodiments

[0032] The present invention will be further described below in conjunction with specific embodiments.

[0033] The raw materials and additives used in the following examples and comparative examples are all commercially available products. The particle size of the graphite electrode powder is 1.5 μm to 3.5 μm, and the carbon content is ≥ 99.9%; the specific surface area of the carbon black is 1000 to 2000 m 2 / g, the specific gravity is 1.9 to 2.0 g / cm³, the carbon content is ≥ 99%, and the content of silicon carbide raw materials is ≥ 99%.

[0034] Example 1

[0035] The production process of the silicon carbide heating element described above includes the following steps:

[0036] (1) Pretreatment of silicon carbide raw materials: Mix 40% of the silicon carbide raw materials with 2‰ of boron nitride and treat them at 1900 °C in a vacuum furnace for 1.5 h.

[0037] (2) Mixing and forming: Mix the remaining 60% of the untreated silicon carbide raw materials and the silicon carbide pretreated in step (1), a total of 80%, 15% of graphite electrode powder (particle size 2.50 μm), 1.0% of carbon black, and 4.0% of binder, and add 15% of water based on the total mass of the above raw material powders. Mix in a mixer for 30 min, and place the uniformly mixed material in a hydraulic press die barrel for extrusion molding to form a rod blank; the binder is obtained by mixing cellulose and polyvinyl alcohol in a mass ratio of 6:4.

[0038] (3) Drying: Dry the rod blank at 180 °C for 9 h.

[0039] (4) First firing: Cover the dried rod blank with silicon particles with a particle size of 20 to 60 mesh, and carry out siliconization firing (the mass ratio of the rod blank to the silicon particles is 100:66). Place it in a vacuum furnace for firing at a temperature of 1700 °C for 8 h. After firing, clean and grind the residue adhering to the rod body.

[0040] (5) Second firing: Cover the rod blank after the first firing in step (4) with 12% of the graphite electrode powder based on the mass of the rod blank, and continue to fire in a vacuum furnace at a temperature of 2200 °C for 2.0 h to obtain a silicon carbide heating element with a diameter of 30 mm, a unit length resistance of 1.0 Ω / 1000 mm at 1050 °C ± 50 °C, and a density of 2.95 g / cm 3 .

[0041] Example 2

[0042] The production process of the silicon carbide heating element described above includes the following steps:

[0043] (1) Pretreatment of silicon carbide raw materials: Mix 40% of the silicon carbide raw materials with 4‰ of boron carbide and treat them at 1950 °C in a vacuum furnace for 1 h.

[0044] (2) Mixing and forming: Mix 90% of the remaining 60% of the unpretreated silicon carbide raw materials and the silicon carbide pretreated in step (1), 6% of graphite electrode powder (particle size 2.90 μm), 0.5% of carbon black, and 3.5% of binder, and add 10% of water based on the total mass of the above raw material powders. Mix in a mixer for 30 min, and place the evenly mixed material in a hydraulic press die cylinder for extrusion forming to form a rod blank;

[0045] The binder is obtained by mixing cellulose and polyvinyl alcohol in a mass ratio of 6:4.

[0046] (3) Drying: Dry the rod blank at 170 °C for 10 h.

[0047] (4) First firing: Cover the dried rod blank with silicon particles with a particle size of 20 - 60 mesh for siliconization firing (the mass ratio of the rod blank to the silicon particles is 100:43), place it in a vacuum furnace for firing, the temperature is 1650 °C, the firing time is 10 h, and clean and grind the residue adhering to the rod body after firing.

[0048] (5) Second firing: Cover the rod blank after the first firing in step (4) with 15% of the mass of the rod blank of graphite electrode powder, and continue to fire in a vacuum furnace at a temperature of 2180 °C for 2.5 h to obtain a silicon carbide rod heating element with a diameter of 30 mm, a unit length resistance of 2.0 Ω / 1000 mm at 1050 °C ± 50 °C, and a density of 2.66 g / cm 3 .

[0049] Example 3

[0050] The production process of the silicon carbide rod heating element described above includes the following steps:

[0051] (1) Pretreatment of silicon carbide raw materials: Mix 45% of silicon carbide raw materials with 6‰ of boron carbide, and treat them at 2000 °C for 1.5 h in a carbon tube furnace under an Ar gas atmosphere.

[0052] (2) Mixing and forming: Mix 85% of the remaining 55% of the unpretreated silicon carbide raw materials and the silicon carbide pretreated in step (1), 10.5% of graphite electrode powder (particle size 2.90 μm), 0.8% of carbon black, and 3.7% of binder, and add 12.5% of water based on the total mass of the above raw material powders. Mix in a mixer for 30 min, and place the evenly mixed material in a hydraulic press die cylinder for extrusion forming to form a rod blank;

[0053] The binder is obtained by mixing cellulose and polyvinyl alcohol in a mass ratio of 7:3.

[0054] (3) Drying: Dry the rod blank at 190 °C for 8 h.

[0055] (4) Primary firing: The dried rod blanks are covered with silicon particles with a particle size of 20 - 60 mesh for siliconization firing (the mass ratio of rod blanks to silicon particles is 100:54), placed in a carbon tube furnace under an Ar atmosphere for firing at a temperature of 2150 °C for 3 h. After firing, the residues adhering to the rod body are cleaned and ground off.

[0056] (5) Secondary firing: The rod blanks after the primary firing in step (4) are covered with 10% of the mass of the rod blanks of graphite electrode powder, and continue to be fired in a carbon tube furnace at a temperature of 2460 °C for 3.0 h to obtain a silicon carbide rod heating element with a diameter of 30 mm, a unit length resistance of 2.5 Ω / 1000 mm at 1050 °C ± 50 °C, and a density of 2.72 g / cm 3 .

[0057] Example 4

[0058] The production process of the silicon carbide rod heating element described above includes the following steps:

[0059] (1) Pretreatment of silicon carbide raw materials: 35% of the silicon carbide raw materials are mixed with 2‰ of boron nitride and treated in a carbon tube furnace under an Ar atmosphere at 2100 °C for 1.0 h.

[0060] (2) Mixing and forming: The remaining 65% of the untreated silicon carbide raw materials and the silicon carbide pretreated in step (1), a total of 83%, 13% of graphite electrode powder (particle size 2.90 μm), 0.5% of carbon black, and 3.5% of binder are mixed, and 13.5% of the sum of the masses of the above raw material powders of water is added. The mixture is mixed in a mixer for 30 min, and the uniformly mixed material is placed in a die cylinder of a hydraulic press for extrusion forming to form rod blanks;

[0061] The binder is obtained by mixing cellulose and polyvinyl alcohol in a mass ratio of 5:5.

[0062] (3) Drying: The rod blanks are dried at 190 °C for 8 h.

[0063] (4) Primary firing: The dried rod blanks are covered with silicon particles with a particle size of 20 - 60 mesh for siliconization firing (the mass ratio of rod blanks to silicon particles is 100:60), placed in a carbon tube furnace under an N2 atmosphere for firing at a temperature of 2200 °C for 2 h. After firing, the residues adhering to the rod body are cleaned and ground off.

[0064] (5) Secondary firing: The rod blanks after the primary firing in step (4) are covered with 10% - 15% of the mass of the rod blanks of graphite electrode powder, and continue to be fired in a carbon tube furnace at a temperature of 2480 °C for 2.5 h to obtain a silicon carbide rod heating element with a diameter of 30 mm, a unit length resistance of 0.8 Ω / 1000 mm at 1050 °C ± 50 °C, and a density of 2.90 g / cm 3 .

[0065] Example 5

[0066] The production process of the silicon carbide heating element described above includes the following steps:

[0067] (1) Pretreatment of silicon carbide raw materials: Mix 40% of silicon carbide raw materials with 3.5‰ of boron nitride and process them in a vacuum furnace at 1900°C for 1.5 h.

[0068] (2) Mixing and forming: Mix the remaining 60% of untreated silicon carbide raw materials with the silicon carbide pretreated in step (1), a total of 86%, 9.4% of graphite electrode powder (particle size 2.90 μm), 1.0% of carbon black, and 3.6% of binder, and add 13% of water based on the total mass of the above raw material powders. Mix them in a mixer for 30 min. Place the evenly mixed material in a hydraulic press die cylinder and extrude it into a rod blank;

[0069] The binder is obtained by mixing cellulose and polyvinyl alcohol in a mass ratio of 6:4.

[0070] (3) Drying: Dry the rod blank at 180°C for 9 h.

[0071] (4) First firing: Cover the dried rod blank with silicon grains with a particle size of 20 - 60 mesh for siliconization firing (the mass ratio of the rod blank to the silicon grains is 100:60). Place it in a vacuum furnace for firing at a temperature of 1700°C for 8 h. After firing, clean and grind the residue adhering to the rod body.

[0072] (5) Second firing: Cover the rod blank after the first firing in step (4) with 12% of graphite electrode powder based on the mass of the rod blank, and continue to fire it in a vacuum furnace at a temperature of 2200°C for 2.0 h to obtain a silicon carbide heating element with a diameter of 30 mm, a unit length resistance of 1.8 Ω / 1000 mm at 1050°C ± 50°C, and a density of 2.79 g / cm 3 .

[0073] Example 6

[0074] The production process of the silicon carbide heating element described above includes the following steps:

[0075] (1) Pretreatment of silicon carbide raw materials: Mix 45% of silicon carbide raw materials with 0.5‰ of boron nitride and process them in a vacuum furnace at 1900°C for 1.5 h.

[0076] (2) Mixing and forming: Mix 90% of the remaining 55% of the unpretreated silicon carbide raw materials and the silicon carbide pretreated in step (1), 5.5% of graphite electrode powder (particle size 2.90 μm), 0.8% of carbon black, and 3.7% of binder, and add 10.8% of water based on the total mass of the above raw material powders. Mix in a mixer for 30 minutes. The uniformly mixed material is placed in a die barrel of a hydraulic press and extruded into a rod blank.

[0077] The binder is obtained by mixing cellulose and polyvinyl alcohol in a mass ratio of 6:4.

[0078] (3) Drying: Dry the rod blank at 180 °C for 9 hours.

[0079] (4) First firing: The dried rod blank is covered with silicon particles with a particle size of 20 - 60 mesh for siliconization firing (the mass ratio of the rod blank to the silicon particles is 100:45), placed in a vacuum furnace for firing at a temperature of 1700 °C for 8 hours. After firing, clean and grind the residue adhering to the rod body.

[0080] (5) Second firing: The rod blank after the first firing in step (4) is covered with 15% of the graphite electrode powder based on the mass of the rod blank, and continues to be fired in a vacuum furnace at a temperature of 2200 °C for 2.0 hours to obtain a silicon carbide rod heating element with a diameter of 30 mm, a unit length resistance of 1.3 Ω / 1000 mm at 1050 °C ± 50 °C, and a density of 2.67 g / cm 3 .

[0081] Comparative Example 1

[0082] A production process of a silicon carbide rod heating element, comprising the following steps:

[0083] (1) Pretreatment of silicon carbide raw materials: Mix 40% of silicon carbide raw materials with 2‰ of boron nitride and treat in a vacuum furnace at 1900 °C for 1.5 hours.

[0084] (2) Mixing and forming: Mix 97% of the remaining 60% of the unpretreated silicon carbide raw materials and the silicon carbide pretreated in step (1), 0.7% of graphite electrode powder (particle size 2.50 μm), 0.5% of carbon black, and 1.8% of binder, and add 8.5% of water based on the total mass of the above raw material powders. Mix in a mixer for 30 minutes. The uniformly mixed material is placed in a die barrel of a hydraulic press and extruded into a rod blank; the binder is obtained by mixing cellulose and polyvinyl alcohol in a mass ratio of 6:4.

[0085] (3) Drying: Dry the rod blank at 180 °C for 9 hours.

[0086] (4) One-time firing: The dried rod blanks are covered with silicon particles with a particle size of 20 - 60 mesh, and subjected to siliconization firing (the mass ratio of rod blanks to silicon particles is 100:12), placed in a vacuum furnace for firing at a temperature of 1700 °C for 8 hours. After firing, the residues adhering to the rod body are cleaned and ground off.

[0087] (5) Two-time firing: The rod blanks after one-time firing in step (4) are covered with 12% graphite electrode powder based on the mass of the rod blanks, and continue to be fired in a vacuum furnace at a temperature of 2200 °C for 2.0 hours to obtain a silicon carbide rod heating element with a diameter of 30 mm, a unit length resistance of 2.9 Ω / 1000 mm at 1050 °C ± 50 °C, and a density of 2.52 g / cm 3 .

[0088] Comparative Example 2

[0089] This comparative example is the same as Example 1, but all the binders are made of polyvinyl alcohol and the cellulose is removed, and the preparation is the same as that of Example 1. The vertical forming exceeds 2000 mm, and the fracture of the rod blanks exceeds 15%. However, when the cellulose is added to the binder in the present invention, there is no phenomenon of rod blank fracture.

[0090] Comparative Example 3

[0091] A production process of a silicon carbide rod heating element includes the following steps:

[0092] (1) Pretreatment of silicon carbide raw materials: 45% of silicon carbide raw materials are mixed with 6‰ of boron carbide, and treated in a carbon tube furnace under an Ar gas atmosphere at 2000 °C for 1.5 hours.

[0093] (2) Mixing and forming: The remaining 55% of the untreated silicon carbide raw materials and the silicon carbide after pretreatment in step (1) in total of 85%, 10.5% of graphite electrode powder (particle size 2.90 μm), 0.8% of carbon black, and 3.7% of binder are mixed, and 12.5% of water based on the sum of the masses of the above raw material powders is added, mixed in a mixer for 30 minutes, and the uniformly mixed material is placed in a hydraulic press die cylinder for extrusion forming to form rod blanks;

[0094] The binder is obtained by mixing cellulose and polyvinyl alcohol according to a mass ratio of 7:3.

[0095] (3) Drying: The rod blanks are dried at 190 °C for 8 hours.

[0096] (4) One-time firing: The dried rod blanks are covered with silicon particles with a particle size of 20 - 60 mesh for siliconization firing (the mass ratio of rod blanks to silicon particles is 100:54), placed in a carbon tube furnace protected by an Ar atmosphere for firing at a temperature of 2460 °C for 2 hours. After firing, the residues adhering to the rod body are cleaned and ground off.

[0097] When Comparative Example 3 was only fired once, the furnace tube had severe shrinkage holes, the service life was within 10 days, and the controllability of the resistance of the heating element became poor. The furnace tube life of the present invention is extended by more than 2 times, meeting the conditions for mass production.

Claims

1. A production process of a silicon carbide heating element, characterized in that: It includes the following steps: (1) Pretreatment of silicon carbide raw materials: Mix the silicon carbide raw materials with additives and conduct pre-firing treatment; the additives are boron nitride or boron carbide; The pre-firing is carried out at 1900 - 1950 °C in a vacuum furnace or at 2000 - 2100 °C in a carbon tube furnace under an Ar gas atmosphere; the added mass of the additives is 0.5 - 6‰ of the silicon carbide raw materials to be pretreated; (2) Mixing and forming: Mix the untreated silicon carbide raw materials with the pretreated silicon carbide, graphite electrode powder, carbon black, and binder, and extrude to form a rod blank; The mass percentage of the untreated silicon carbide raw materials to the pretreated silicon carbide is 55% - 65%:35% - 45%; the binder is obtained by mixing cellulose and polyvinyl alcohol in a mass ratio of 7:3 - 5:5; The mass percentage of the untreated silicon carbide raw materials, the pretreated silicon carbide, graphite electrode powder, carbon black, and binder is 80% - 90% silicon carbide, 6% - 15% graphite electrode powder, 0.5% - 1.0% carbon black, and 3.5% - 4% binder; (3) Drying: Dry the rod blank; (4) First firing: Fire in a carbon tube furnace at 2150 - 2200 °C or in a vacuum furnace at 1650 - 1700 °C; (5) Second firing: Fire in a carbon tube furnace at 2460 - 2480 °C or in a vacuum furnace at 2180 - 2200 °C to obtain a silicon carbide rod heating element.

2. The production process of the silicon carbide heating element according to claim 1, characterized in that: The purity of the silicon carbide described in step (1) is above 99%.

3. The production process of the silicon carbide heating element according to claim 2, characterized in that: The pre-firing in step (1) is carried out for 1 h - 1.5 h in a vacuum furnace or for 1 h - 1.5 h in a carbon tube furnace under an Ar gas atmosphere.

4. The production process of the silicon carbide heating element according to claim 1, characterized in that: The particle size of the graphite electrode powder is 1.5 μm to 3.5 μm, and the carbon content is ≥99.9%; the specific surface area of the carbon black is 1000 to 2000 m 2 / g, the specific gravity is 1.9 to 2.0 g / cm³, and the carbon content is ≥99%.

5. The production process of the silicon carbide heating element according to claim 1, characterized in that: The drying temperature in step (3) is 170 - 190 °C and the time is 8 - 10 h; the firing time in the carbon tube furnace in step (4) is 2 - 3 h; or the firing time in the vacuum furnace is 8 - 10 h.

6. The production process of the silicon carbide heating element according to claim 1, characterized in that: The firing time in the carbon tube furnace in step (5) is 2.5 - 3.0 h; or the firing time in the vacuum furnace is 2.0 - 2.5 h.

7. A silicon carbide heating element, characterized in that: It is produced by the production process of the silicon carbide rod heating element according to any one of claims 1 - 6.