Electrode structure for silicon carbide crystal growth resistance furnace

Abstract

The application discloses a kind of electrode structures for silicon carbide crystal growth resistance furnace, assemble in furnace cavity, including electrode main body and insulating sleeve, wherein, electrode main body, the first end of electrode main body is electrically connected with power component, second end then projects on the inner wall of furnace cavity, and extend to heating body connection;Insulating sleeve is set on the electrode main body between furnace cavity and heating body;By insulating sleeve to cover electrode main body, and then form isolation with gas medium, in high temperature stage, can effectively avoid ionization phenomenon to occur, so that the speed of temperature rise is not affected, enhance the reliability of overall heating work, applied to resistance furnace equipment, can provide a more suitable environment for silicon carbide growth.

Description

Technical Field

[0001] This invention relates to the field of resistance furnace structure, and more particularly to an electrode insulation structure for a silicon carbide crystal growth resistance furnace. Background Technology

[0002] Silicon carbide is a crystalline inorganic compound with the chemical formula SiC. It is grown from raw materials such as quartz sand, petroleum coke, and sawdust in a smelting environment of 2000-2700 degrees Celsius. The smelting equipment includes electric resistance furnaces and flame furnaces. Compared with flame furnaces, electric resistance furnaces have advantages such as higher thermal efficiency, the ability to use various media in various process atmospheres, higher temperature accuracy, no environmental pollution, and smaller footprint. Therefore, electric resistance furnaces can provide more stable temperature conditions and are more suitable for the growth process of silicon carbide.

[0003] The structure of a resistance furnace typically includes: a main body made of metal, a furnace cavity constructed of high-temperature resistant materials, electrode structures protruding from the inner wall of the furnace cavity, and these electrode structures connected to the heating element. However, during use, it has been found that during silicon carbide growth, when the temperature exceeds 2000 degrees Celsius and argon gas (a protective gas) is introduced, gas ionization discharge occurs between the electrodes and the inner wall of the furnace cavity or other electrical grounding points. This causes ablation of the electrodes or nearby structural components, reducing the power supplied to the heater, limiting the heating rate, decreasing efficiency, increasing the failure rate, and preventing the furnace from operating reliably for extended periods. Therefore, the electrode structure acts as a bridge between current and voltage input to the internal heating element, and its structure has a significant impact on the overall working quality of the resistance furnace. Thus, a more rationally designed electrode structure is urgently needed for resistance furnace equipment to provide a more stable environment for silicon carbide growth. Summary of the Invention

[0004] In response to the technical problem mentioned above, during the smelting and growth of silicon carbide in a resistance furnace, when the temperature exceeds 2000 degrees Celsius and a protective gas is introduced, a gas ionization discharge phenomenon occurs between the electrode and the inner wall of the furnace cavity or other electrical grounding points, causing the electrode or nearby structural components to ablate, reducing the power supplied to the heater, thus limiting the heating rate and reducing efficiency, this invention provides a new solution.

[0005] To achieve the above objectives, the present invention provides an electrode structure for a silicon carbide crystal growth resistance furnace, assembled inside the furnace cavity, comprising:

[0006] The electrode body has a first end electrically connected to the power element and a second end protruding from the inner wall of the furnace cavity and extending to the heating element.

[0007] An insulating sleeve is fitted onto the electrode body between the furnace cavity and the heating element.

[0008] As an improvement to this application, the insulating sleeve is made of hexagonal boron nitride.

[0009] As an improvement to this application, the density of the hexagonal boron nitride is ≥2.24 g / cm³. 3 .

[0010] As an improvement to this application, the thickness of the insulating sleeve is 15mm.

[0011] As an improvement of this application, the insulating sleeve is further provided with multiple sets of annular grooves in the circumferential direction.

[0012] As an improvement of this application, the outer diameter of the edge material forming the annular groove of the insulating sleeve is also provided with a chamfered corner structure.

[0013] As an improvement of this application, the number of annular grooves is 4.

[0014] As an improvement of this application, the bevel radius of the bevel structure is 1mm.

[0015] As an improvement to this application, the depth of the annular groove is 11 mm.

[0016] As an improvement to this application, the width of the groove is 3mm.

[0017] The beneficial effects of this invention are as follows: Compared with the prior art, the electrode structure provided by this invention for a silicon carbide crystal growth resistance furnace is assembled inside the furnace cavity and includes an electrode body and an insulating sleeve. The electrode body has a first end electrically connected to a power element and a second end extending out of the inner wall of the furnace cavity and connected to a heating element. The insulating sleeve is fitted onto the electrode body between the furnace cavity and the heating element. By covering the electrode body with the insulating sleeve, it is isolated from the gas medium. In the high-temperature stage, it can effectively avoid the occurrence of ionization, so that the heating rate is not affected, and the reliability of the overall heating operation is enhanced. When applied to resistance furnace equipment, it can provide a more suitable environment for the growth of silicon carbide. Attached Figure Description

[0018] Figure 1 This is a perspective view of the present invention;

[0019] Figure 2 This is an exploded view of the present invention;

[0020] Figure 3 This is a schematic diagram showing the fit between the electrode body and the insulating sleeve of the present invention.

[0021] The symbols for the main components are explained below:

[0022] 1. Electrode body; 2. Insulating sleeve; 21. Annular groove; 3. Furnace cavity; 4. Heating element. Detailed Implementation

[0023] To more clearly illustrate the present invention, the invention will be further described below with reference to the accompanying drawings.

[0024] In the following description, specific examples of general elections are given to provide a more in-depth understanding of the invention. It is obvious that the described embodiments are merely some, not all, of the embodiments of the invention. It should be understood that the specific embodiments are used only to explain the invention and are not intended to limit the invention.

[0025] It should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of a feature, whole, step, operation, element, or component, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, or combinations thereof.

[0026] Silicon carbide is a crystalline inorganic compound with the chemical formula SiC. It is grown from raw materials such as quartz sand, petroleum coke, and sawdust in a smelting environment of 2000-2700 degrees Celsius. The smelting equipment includes electric resistance furnaces and flame furnaces. Compared with flame furnaces, electric resistance furnaces have advantages such as higher thermal efficiency, the ability to use various media in various process atmospheres, higher temperature accuracy, no environmental pollution, and smaller footprint. Therefore, electric resistance furnaces can provide more stable temperature conditions and are more suitable for the growth process of silicon carbide.

[0027] The structure of a resistance furnace typically includes: a main body made of metal, a furnace cavity constructed of high-temperature resistant materials, electrode structures protruding from the inner wall of the furnace cavity, and these electrode structures connected to the heating element. However, during use, it has been found that during silicon carbide growth, when the temperature exceeds 2000 degrees Celsius and argon gas (a protective gas) is introduced, gas ionization discharge occurs between the electrodes and the inner wall of the furnace cavity or other electrical grounding points. This causes ablation of the electrodes or nearby structural components, reducing the power supplied to the heater, limiting the heating rate, decreasing efficiency, increasing the failure rate, and preventing the furnace from operating reliably for extended periods. Therefore, the electrode structure acts as a bridge between current and voltage input to the internal heating element, and its structure has a significant impact on the overall working quality of the resistance furnace. Thus, a more rationally designed electrode structure is urgently needed for resistance furnace equipment to provide a more stable environment for silicon carbide growth.

[0028] To address the aforementioned technical problems, this application provides an electrode structure for a silicon carbide crystal growth resistance furnace. Please refer to [link to relevant documentation]. Figures 1 to 3The electrode body 1 and the insulating sleeve 2 are assembled inside the furnace cavity 3. The first end of the electrode body 1 is electrically connected to the power element, and the second end protrudes from the inner wall of the furnace cavity 3 and extends to the heating element 4. The insulating sleeve 2 is sleeved on the electrode body 1 between the furnace cavity 3 and the heating element 4.

[0029] The commonly used gaseous medium is an inert gas, such as argon. Argon has good chemical inertness under normal conditions, but under high frequency, high pressure, or high thermal radiation, it can further decompose into argon ions. Argon ions exhibit good conductivity and can form white, blue, purple, or red electric arcs depending on the voltage energy they receive. By covering the electrode body with an insulating sleeve 4, it is isolated from the gaseous medium. At high temperatures, ionization can be effectively avoided, so that the heating rate is not affected and the overall heating reliability is enhanced. When applied to resistance furnace equipment, it can provide a more suitable environment for the growth of silicon carbide.

[0030] The insulating sleeve is made of hexagonal boron nitride, a substance with a molecular arrangement similar to graphite, the difference being that hexagonal boron nitride uses SP. 3 Hybridization, while graphite employs SP. 2 Due to its hybrid nature, hexagonal boron nitride does not contain free ions and belongs to a covalent compound with a more stable structure. Since the ions do not ionize and therefore do not generate electrical properties, it provides excellent insulation. Using this material to prepare an insulating sleeve can effectively isolate the electrode body from the gas medium. Furthermore, the density of hexagonal boron carbide is chosen to be greater than 2.24 g / cm³. Using high-density hexagonal boron nitride further ensures the working stability of the insulating sleeve. Even at high temperatures, it will not cause the electrode body 1 and the insulating sleeve 2 to loosen, thus preventing ionization and the resulting temperature rise.

[0031] It is easy to see that the greater the thickness of the insulating sleeve 2, the better the isolation stability. In practical applications, the thickness of the insulating sleeve is 15mm.

[0032] In practical use, it was found that after the insulating sleeve 2 was installed, the temperature rise was relatively slow when the temperature reached the range of 2000-2600 degrees Celsius. Considering that the material of the electrode body 1 is copper metal, the conductivity of the metal conductor will decrease during the temperature rise, which will lead to a decrease in power output. The installation of the insulating sleeve further affects the temperature of the electrode body. Based on the above situation, multiple sets of annular grooves 21 are also opened in the circumferential direction of the insulating sleeve 2. Through the further heat dissipation of the electrode body by the annular grooves 21, the temperature rise is more stable.

[0033] Furthermore, the outer diameter of the edge material of the insulating sleeve 2 forming the annular groove 21 is also provided with a chamfered structure (not shown in the figure). It is easy to understand that before argon is introduced into the equipment, the air needs to be extracted first to form a vacuum state in the furnace cavity 3 before the argon can be rushed into the cavity. However, the purity of the argon and the small amount of air left in the furnace cavity 3 may cause a brief ionization phenomenon at the connection between the electrode body 1 and the heating element 4. The electric arc generated by the ionization will damage the sharp corner of the outer diameter of the annular groove 21. Therefore, the outer diameter of the edge material of the insulating sleeve 2 forming the annular groove is also provided with a chamfered structure to prevent the electric arc from directly damaging the insulating sleeve.

[0034] As a specific implementation specification, this application specifies that the insulation thickness is 15 mm, the number of annular grooves 21 is 4, the radius of the beveled corner structure is 1 mm, the depth of the annular grooves 21 is 11 mm, and the width of the annular grooves 21 is 3 mm.

[0035] The effects of this application will be further explained below with reference to specific embodiments; Specific Implementation Example 1:

[0037] Heating element: Graphite heating element; Inner diameter of the cavity formed by the heating element: 400×300×300, unit: cm;

[0038] Operating voltage: 380V;

[0039] The tested process temperature range is 2000-2600 degrees Celsius.

[0040] Gas medium conditions: The vacuum level in the furnace chamber is achieved using a vacuum pump, followed by the introduction of argon gas as a protective gas. Control group: Electrode body treated conventionally;

[0041] Example 1: An insulating sleeve is fitted onto the electrode body. The specifications of the insulating sleeve are: thickness: 15mm, length: 40mm, material: hexagonal boron nitride, material density: 2.24g / cm³. 3 ;

[0042] The test items are: the actual time required for the temperature to rise from 2000 to 2600 degrees Celsius and the actual temperature. The allowable error is ±2. The control group and Example 1 were tested three times each, and the average value of the three experimental data was recorded.

[0043] The experimental results are shown in Table 1 below:

[0044] Table 1

[0045]

[0046] It is easy to see from the table above that both the control group and the example can achieve the initial target temperature, but the time required exceeds the predetermined time for both groups; the control group requires 26 minutes longer than the preset time, while in example 1, the time required is 8 minutes longer than the predetermined time. It can be seen that by reducing the impact of electric arc through the insulating sleeve, the reliability of the resistance furnace is significantly improved. Specific Implementation Example 2:

[0048] Heating element: Graphite heating element; Inner diameter of the cavity formed by the heating element: 400×300×300, unit: cm;

[0049] Operating voltage: 380V;

[0050] The tested process temperature range is 2000-2600℃;

[0051] Gas medium conditions: The vacuum level in the furnace chamber is increased by a vacuum pump, and then argon gas is introduced as a protective gas. Example 2: An insulating sleeve is fitted onto the electrode body. The specifications of the insulating sleeve are: thickness: 15mm, length: 40mm, material: hexagonal boron nitride; material density: 2.24g / cm³. 3 Two annular grooves are made on the insulating sleeve. The grooves are 11mm deep, 3cm wide, and have a chamfer radius of 1mm.

[0052] Example 3: An insulating sleeve was fitted onto the electrode body. The specifications of the insulating sleeve were: thickness: 15mm, length: 40mm, material: hexagonal boron nitride, material density: 2.24g / cm³. 3 Four annular grooves are made on the insulating sleeve. The grooves are 11mm deep, 3cm wide, and have a chamfer radius of 1mm.

[0053] Example 3: An insulating sleeve was fitted onto the electrode body. The specifications of the insulating sleeve were: thickness: 15mm, length: 40mm, material: hexagonal boron nitride, material density: 2.24g / cm³. 3 Six annular grooves are made on the insulating sleeve, with a groove depth of 11mm, a width of 3cm, and a chamfer radius of 1mm.

[0054] The test items are: the actual time required for the temperature to rise from 2000 to 2600 degrees Celsius and the actual temperature. The allowable error for the temperature is ±2. Examples 2, 3 and 4 were tested three times each, and the average value of the three experimental data was recorded.

[0055] The experimental results are shown in Table 2 below:

[0056] Table 2

[0057]

[0058] It is easy to see from the table above that the temperatures in Examples 2, 3, and 4 can all reach the initial target temperature, but the time required is longer than the predetermined time. However, compared with Example 1, the actual time values ​​of the above examples are closer to the predetermined time values. The annular grooves opened in Examples 2 and 4 are quite different, but the formation time is similar with no obvious difference. In Example 3, the strip annular grooves provide a better effect in this stage of processing. Analysis shows that the acquisition of four annular grooves can keep the heat dissipation performance of the electrode body within a temperature range, thereby enabling better power delivery. Specific Implementation Example 3:

[0060] Heating element: Graphite heating element; Inner diameter of the cavity formed by the heating element: 400×300×300, unit: cm;

[0061] Operating voltage: 380V;

[0062] The tested process temperature range is 2000-2600℃;

[0063] Gas medium conditions: The vacuum level in the furnace chamber is achieved using a vacuum pump, followed by the introduction of argon gas as a protective gas. Control group: Electrode body treated conventionally;

[0064] Example 5: An insulating sleeve was fitted onto the electrode body. The specifications of the insulating sleeve were: thickness: 15mm, length: 40mm, material: hexagonal boron nitride, material density: 2.23g / cm³. 3 Four annular grooves are made on the insulating sleeve. The grooves are 11mm deep, 3cm wide, and have a chamfer radius of 1mm.

[0065] Example 6: An insulating sleeve was fitted onto the electrode body. The specifications of the insulating sleeve were: thickness: 15mm, length: 40mm, material: hexagonal boron nitride, material density: 2.24g / cm³. 3 Four annular grooves are made on the insulating sleeve. The grooves are 11mm deep, 3cm wide, and have a chamfer radius of 1mm.

[0066] Example 7: An insulating sleeve is fitted onto the electrode body. The specifications of the insulating sleeve are: thickness: 15mm, length: 40mm, material: hexagonal boron nitride, material density: 2.25g / cm³. 3 Six annular grooves are made on the insulating sleeve, with a groove depth of 11mm, a width of 3cm, and a chamfer radius of 1mm.

[0067] Example 8: An insulating sleeve was fitted onto the electrode body. The specifications of the insulating sleeve were: thickness: 15mm, length: 40mm, material: hexagonal boron nitride, material density: 2.26g / cm³. 3 Six annular grooves are made on the insulating sleeve, with a groove depth of 11mm, a width of 3cm, and a chamfer radius of 1mm.

[0068] The test items are: the actual time required for the temperature to rise from 2000 to 2600 degrees Celsius and the actual temperature. The allowable error for the temperature is ±2. Examples 2, 3 and 4 were tested three times each, and the average value of the three experimental data was recorded.

[0069] The experimental results are shown in Table 3 below:

[0070] Table 3

[0071]

[0072] It is clear from the table above that in Examples 5 to 8, the impact of different densities on the power transmission of the resistance furnace was further examined. The results show that Examples 5-8 all achieved the required temperature, and the actual time difference was not significant. Therefore, it can be considered that the density of hexagonal boron nitride selected is 2.23-2.26 g / cm³. 3 The impact on the power of the resistance furnace is similar within the range, and both can effectively reduce the impact of argon ionization on heating power.

[0073] To further investigate the stability under different densities, 20 experiments were conducted on Examples 5-8, and the surface shape of the insulating sleeves of Examples 5-8 was observed. Details are shown in Table 4.

[0074] Table 4

[0075]

[0076] It is easy to see from the table above that the surface condition, whether there is deformation, and whether there is cracking are all good. Among them, Examples 6 to 8 can maintain good performance in all three aspects, while Example 5 shows a small amount of dust on the surface. The dust may be nano-level furnace material or hexagonal boron nitride powder generated due to insufficient forming density of the insulating sleeve. The powder is not conducive to the vacuuming process of the instrument and will block the channels. Therefore, the density range of Examples 6-8 is selected. Considering the convenience of the die casting process, Example 6 (same as Example 3) is preferred as the best example.

[0077] The advantages of this invention are:

[0078] 1) By covering the electrode body with an insulating sleeve, it is isolated from the gas medium. At high temperature, it can effectively prevent ionization, so that the heating rate is not affected and the overall heating reliability is enhanced. When applied to resistance furnace equipment, it can provide a more suitable environment for the growth of silicon carbide.

[0079] 2) Multiple sets of annular grooves are also formed in the circumferential direction of the insulating sleeve. The annular grooves further dissipate heat from the electrode body, making the temperature rise more stable.

[0080] The above-disclosed embodiments are merely a few specific examples of the present invention, but the present invention is not limited thereto. Any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An electrode structure for a silicon carbide crystal growth resistance furnace, assembled inside the furnace cavity, characterized in that, include: The electrode body has a first end electrically connected to the power element and a second end protruding from the inner wall of the furnace cavity and extending to the heating element. An insulating sleeve is fitted onto the electrode body between the furnace cavity and the heating element; The insulating sleeve has a thickness of 15mm; multiple sets of annular grooves are formed in the circumferential direction of the insulating sleeve; the outer diameter of the edge material forming the annular grooves of the insulating sleeve is also provided with a chamfer structure; the insulating sleeve is made of hexagonal boron nitride.

2. The electrode structure for a silicon carbide crystal growth resistance furnace according to claim 1, characterized in that, The density of the hexagonal boron nitride is ≥2.24 g / cm³. 3 .

3. The electrode structure for a silicon carbide crystal growth resistance furnace according to claim 1, characterized in that, The number of annular grooves is 4.

4. The electrode structure for a silicon carbide crystal growth resistance furnace according to claim 2, characterized in that, The bevel radius of the bevel structure is 1 mm.

5. The electrode structure for a silicon carbide crystal growth resistance furnace according to claim 4, characterized in that, The depth of the annular groove is 11 mm.

6. The electrode structure for a silicon carbide crystal growth resistance furnace according to claim 5, characterized in that, The width of the groove is 3mm.

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