A ceramic silicon nitride heating element

Abstract

The present invention discloses a ceramic silicon nitride heating element, comprising a silicon nitride substrate, a heat source and a heat vacuum chamber. A silicon nitride ceramic sheet one and a silicon nitride ceramic sheet two are sintered together to form a silicon nitride substrate. When the fired silicon nitride ceramic sheet is sintered again, the structural stress is very small. A heat vacuum chamber is provided on both the silicon nitride ceramic sheet one and the silicon nitride ceramic sheet two. The heat vacuum chamber is a prefabricated chamber during sintering. When the initial silicon nitride heating element operates normally, a seal is provided at the opening of the heat vacuum chamber. When the initial heat source fails, the seal is opened and a spare heat source is placed in the heat vacuum chamber, so that the silicon nitride substrate can still be used, thereby reducing maintenance costs.

Description

Technical Field

[0001] The present invention relates to the technical field of heating elements, in particular to a ceramic silicon nitride heating element. Background Art

[0002] Existing silicon nitride heaters are typically sintered into a single piece, using a heating wire embedded in silicon nitride powder and then sintered in a mold. If the pre-embedded heating wire shorts or breaks, the heater becomes useless, increasing repair costs. Furthermore, the one-shot sintering process can easily create sintering stress, making it prone to breakage during use. Therefore, a new silicon nitride heater is needed to address these issues. Summary of the Invention

[0003] The purpose of the present invention is to provide a ceramic silicon nitride heating element to solve the problems existing in the above-mentioned prior art, reduce structural stress, extend the service life of the silicon nitride heating element, and also reduce maintenance costs.

[0004] To achieve the above object, the present invention provides the following solution: The present invention provides a ceramic silicon nitride heating element, comprising

[0005] A silicon nitride substrate, the silicon nitride substrate comprising a first silicon nitride ceramic sheet and a second silicon nitride ceramic sheet, wherein the first silicon nitride ceramic sheet and the second silicon nitride ceramic sheet are sintered together to form the silicon nitride substrate; and

[0006] a heat source, the heat source being printed on the surface of the first silicon nitride ceramic sheet or the second silicon nitride ceramic sheet, wherein the lead-out electrodes of the heat source are respectively connected to the positive and negative electrodes of a power supply; and

[0007] A heating vacuum cavity is provided on each of the silicon nitride ceramic sheet one and the silicon nitride ceramic sheet two. The heating vacuum cavity is a prefabricated cavity during sintering. The opening of the heating vacuum cavity is sealed by a sealing member. The heating vacuum cavity is used to accommodate a backup heating source.

[0008] Preferably, the silicon nitride substrate is a cylinder, the silicon nitride ceramic sheet one and the silicon nitride ceramic sheet two are both semi-cylinders with a semicircular cross-section, and the heat source is printed on the inner surface of the silicon nitride ceramic sheet one or the silicon nitride ceramic sheet two; after sintering is completed, the heat source is located in the middle position of the silicon nitride substrate.

[0009] Preferably, one or more heating vacuum cavities are uniformly distributed along the circumference of the silicon nitride ceramic sheet one and the silicon nitride ceramic sheet two.

[0010] Preferably, the silicon nitride substrate is a rectangular body, the silicon nitride ceramic sheet one and the silicon nitride ceramic sheet two are symmetrically arranged, and the heat source is printed on the inner surface of the silicon nitride ceramic sheet one or the silicon nitride ceramic sheet two; after sintering is completed, the heat source is located in the middle position of the silicon nitride substrate.

[0011] Preferably, a heating vacuum cavity parallel to the connection surface is provided on each of the first silicon nitride ceramic sheet and the second silicon nitride ceramic sheet.

[0012] Preferably, the end of the silicon nitride substrate is provided with two wiring terminals, and the lead-out electrodes of the heat source are respectively connected to the positive and negative poles of the power supply through the wiring terminals; the end of the silicon nitride substrate close to the wiring terminals is provided with an insulating and heat-insulating sleeve on the outside.

[0013] Preferably, the heat source is a high-temperature electric heating film.

[0014] Preferably, the backup heating source includes a heating wire and a lead-out electrode, both ends of the heating wire are connected to the lead-out electrode, the heating wire is made of tungsten wire, the lead-out electrode is made of molybdenum wire, and the two lead-out electrodes are respectively connected to the positive and negative poles of the power supply.

[0015] Compared with the prior art, the present invention has achieved the following beneficial technical effects:

[0016] The ceramic silicon nitride heating element in the present invention includes a silicon nitride substrate, a heat source and a heat vacuum chamber. The silicon nitride ceramic sheet one and the silicon nitride ceramic sheet two are sintered into one to form a silicon nitride substrate. When the fired silicon nitride ceramic sheet is sintered again, its structural stress is very small. The silicon nitride ceramic sheet one and the silicon nitride ceramic sheet two are both provided with a heat vacuum chamber. The heat vacuum chamber is a prefabricated chamber during sintering. When the initial silicon nitride heating element is working normally, the sealing member at the opening of the heat vacuum chamber is sealed. When the initial heat source fails, the sealing member is opened and a spare heat source is placed in the heat vacuum chamber so that the silicon nitride substrate can still be used, thereby reducing maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a cross-sectional view of the internal structure of a ceramic silicon nitride heating element in an embodiment of the present invention;

[0019] Figure 2 Schematic diagram of the disassembly of silicon nitride ceramic sheet 1 and silicon nitride ceramic sheet 2;

[0020] Figure 3 This is the distribution diagram of the heat-generating vacuum cavity when the silicon nitride substrate is a cylinder;

[0021] Figure 4 This is the distribution diagram of the heat-generating vacuum cavity when the silicon nitride substrate is a rectangular body;

[0022] Among them, 1. Silicon nitride substrate; 2. Heat source; 3. Insulation sleeve; 4. Lead-out electrode; 5. Silicon nitride ceramic sheet 1; 6. Silicon nitride ceramic sheet 2; 7. Heating vacuum chamber. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] The purpose of the present invention is to provide a ceramic silicon nitride heating element to solve the problems existing in the above-mentioned prior art, reduce structural stress, extend the service life of the silicon nitride heating element, and also reduce maintenance costs.

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figures 1-4 As shown, the present invention provides a ceramic silicon nitride heating element, comprising

[0027] A silicon nitride substrate 1, comprising a silicon nitride ceramic sheet 1 5 and a silicon nitride ceramic sheet 2 6, wherein the silicon nitride ceramic sheet 1 5 and the silicon nitride ceramic sheet 2 6 are sintered together to form the silicon nitride substrate 1; and

[0028] A heat source 2, the heat source 2 is printed on the surface of the silicon nitride ceramic sheet 1 5 or the silicon nitride ceramic sheet 2 6, and the lead electrodes 4 of the heat source 2 are respectively connected to the positive and negative poles of the power supply; and

[0029] A heating vacuum cavity 7 is provided on each of the silicon nitride ceramic sheet 1 5 and the silicon nitride ceramic sheet 2 6. The heating vacuum cavity 7 is a prefabricated cavity during sintering, and the opening of the heating vacuum cavity 7 is sealed by a sealing member. The heating vacuum cavity 7 is used to accommodate a backup heating source 2.

[0030] The silicon nitride substrate 1 is a pre-fired silicon nitride ceramic sheet. When the pre-fired silicon nitride ceramic sheet is used for re-sintering, its structural stress is very small. A heating vacuum chamber 7 is provided on both the silicon nitride ceramic sheet 1 5 and the silicon nitride ceramic sheet 2 6. The heating vacuum chamber 7 is a prefabricated chamber during sintering. When the initial silicon nitride heating element is working normally, the opening of the heating vacuum chamber 7 is sealed by a seal. When the initial heating source 2 fails, the seal is opened and a spare heating source 2 is placed in the heating vacuum chamber 7, so that the silicon nitride substrate 1 can still be used, reducing maintenance costs.

[0031] In one embodiment, Figure 3 As shown, the silicon nitride substrate 1 is a cylinder, the silicon nitride ceramic sheet 1 5 and the silicon nitride ceramic sheet 2 6 are both semi-cylinders with semicircular cross-sections, and the heat source 2 is printed on the inner surface of the silicon nitride ceramic sheet 1 5 or the silicon nitride ceramic sheet 2 6; after sintering is completed, the heat source 2 is located in the middle position of the silicon nitride substrate 1; one or more heating vacuum cavities 7 are evenly distributed along the circumference of the silicon nitride ceramic sheet 1 5 and the silicon nitride ceramic sheet 2 6.

[0032] In one embodiment, Figure 4 As shown, the silicon nitride substrate 1 is a rectangular body, the silicon nitride ceramic sheet 1 5 and the silicon nitride ceramic sheet 2 6 are symmetrically arranged, and the heat source 2 is printed on the inner surface of the silicon nitride ceramic sheet 1 5 or the silicon nitride ceramic sheet 2 6; after sintering is completed, the heat source 2 is located in the middle position of the silicon nitride substrate 1; the silicon nitride ceramic sheet 1 5 and the silicon nitride ceramic sheet 2 6 are both provided with a heating vacuum cavity 7 parallel to the connection surface.

[0033] In one embodiment, two terminals are provided at the end of the silicon nitride substrate 1, and the lead-out electrodes 4 of the heat source 2 are respectively connected to the positive and negative poles of the power supply through the terminals; an insulating heat-insulating sleeve 3 is provided on the outer side of the end of the silicon nitride substrate 1 close to the terminal.

[0034] In one embodiment, to further improve processing efficiency and reduce large-scale processing costs, the heat source 2 utilizes a high-temperature electric heating film, which is printed onto the lower silicon nitride ceramic sheet. After the high-temperature electric heating film is printed on the silicon nitride ceramic sheet 2 6 , the two silicon nitride ceramic sheets are stacked and sintered to form a single ceramic silicon nitride heating element.

[0035] In one embodiment, the backup heating source 2 includes a heating wire and a lead-out electrode. Both ends of the heating wire are connected to the lead-out electrode. The heating wire is made of tungsten wire, and the lead-out electrode is made of molybdenum wire. The two lead-out electrodes are connected to the positive and negative poles of the power supply respectively. Tungsten wire is used as the heating source 2, and aluminum wire is used as the lead-out electrode. The tungsten wire is connected to the molybdenum wire. The tungsten wire and the molybdenum wire are placed in the heating vacuum chamber 7. The diameters of the tungsten wire and the molybdenum wire are 0.01-0.5mm. In experimental studies, it was found that the diameters of the tungsten wire and the aluminum wire have an impact on the reliability and leakage safety of the silicon nitride heating element. Since the tungsten wire is connected to the molybdenum wire and is placed in the silicon nitride substrate 1, the density of the silicon nitride substrate 1 made by high temperature and high pressure process basically reaches 100%. The tungsten wire and the molybdenum wire are isolated from the air. If the heating element breaks during use, The cross-section of the tungsten and molybdenum wires is exposed to the air. At the moment the silicon nitride heater breaks, the tungsten and molybdenum wires exposed to water or air oxidize, forming an oxidized insulating protective layer on their surface. When the cross-sectional diameter of the tungsten and molybdenum wires is within a certain range, the oxidized insulating protective layer can provide safety protection. Experiments have shown that when the diameter of the tungsten and molybdenum wires is within 0.5mm, the oxidized protective layer can ensure the reliability and leakage safety of the silicon nitride heater, completely solving the safety problem of the silicon nitride heater. The diameter of the tungsten and molybdenum wires in use is generally 0.01-0.15mm.

[0036] The seal at the opening of the heating vacuum chamber 7 can be a silicon nitride ceramic seal, and a through hole is reserved on the seal for passing the lead-out electrode. Then, the periphery of the seal and the opening and through hole of the heating vacuum chamber 7 are sealed and filled with high-temperature resistant sealant. In this way, when the initial heating source 2 is working normally, the heating vacuum chamber 7 is in a vacuum state, which does not affect the overall heating performance of the ceramic silicon nitride heating element; when the initial heating source 2 fails, the maintenance personnel can manually open the seal, and then put the spare heating source 2 into the heating vacuum chamber 7. The heating wire of the spare heating source 2 is set into the heating vacuum chamber 7, and the molybdenum wire as the lead-out electrode is connected to the lead-out electrode 4 after passing through the through hole, and then the seal is refilled and sealed to form a new ceramic silicon nitride heating element; this allows the ceramic silicon nitride heating element to be repaired in the simplest and quickest way without replacing it with a new one, thereby reducing maintenance costs.

[0037] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all perspectives, the embodiments should be regarded as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description. It is intended that all changes that fall within the meaning and range of equivalents of the claims be included in the present invention, and any reference signs in the claims should not be construed as limiting the claims to which they relate.

[0038] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A ceramic silicon nitride heating element, characterized in that: include A silicon nitride substrate, the silicon nitride substrate comprising a first silicon nitride ceramic sheet and a second silicon nitride ceramic sheet, wherein the first silicon nitride ceramic sheet and the second silicon nitride ceramic sheet are sintered together to form the silicon nitride substrate; as well as a heat source, the heat source being printed on the surface of the first silicon nitride ceramic sheet or the second silicon nitride ceramic sheet, wherein the lead-out electrodes of the heat source are respectively connected to the positive and negative electrodes of a power supply; and A heating vacuum cavity is provided on each of the silicon nitride ceramic sheet one and the silicon nitride ceramic sheet two. The heating vacuum cavity is a prefabricated cavity during sintering. The opening of the heating vacuum cavity is sealed by a sealing member. The heating vacuum cavity is used to accommodate a backup heating source.

2. The ceramic silicon nitride heating element according to claim 1, characterized in that: The silicon nitride substrate is a cylinder, and the silicon nitride ceramic sheet one and the silicon nitride ceramic sheet two are both semi-cylinders with semicircular cross-sections. The heat source is printed on the inner surface of the silicon nitride ceramic sheet one or the silicon nitride ceramic sheet two; after sintering is completed, the heat source is located in the middle position of the silicon nitride substrate.

3. The ceramic silicon nitride heating element according to claim 2, characterized in that: One or more heating vacuum cavities are uniformly distributed along the circumference of the silicon nitride ceramic sheet one and the silicon nitride ceramic sheet two.

4. The ceramic silicon nitride heating element according to claim 1, wherein: The silicon nitride substrate is a rectangular body, the silicon nitride ceramic sheet one and the silicon nitride ceramic sheet two are symmetrically arranged, and the heat source is printed on the inner surface of the silicon nitride ceramic sheet one or the silicon nitride ceramic sheet two; after sintering is completed, the heat source is located in the middle position of the silicon nitride substrate.

5. The ceramic silicon nitride heating element according to claim 4, characterized in that: The first silicon nitride ceramic sheet and the second silicon nitride ceramic sheet are both provided with a heating vacuum cavity parallel to the connection surface.

6. The ceramic silicon nitride heating element according to claim 1, characterized in that: The end of the silicon nitride substrate is provided with two terminals, and the lead-out electrodes of the heat source are connected to the positive and negative poles of the power supply through the terminals respectively; the end of the silicon nitride substrate close to the terminals is provided with an insulating sleeve on the outside.

7. The ceramic silicon nitride heating element according to claim 1, characterized in that: The heat source adopts a high-temperature electric heating film.

8. The ceramic silicon nitride heating element according to claim 1, characterized in that: The backup heating source includes a heating wire and a lead-out electrode. Both ends of the heating wire are connected to the lead-out electrode. The heating wire is made of tungsten wire, and the lead-out electrode is made of molybdenum wire. The two lead-out electrodes are respectively connected to the positive and negative poles of the power supply.

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