A heating element for a heating device and a method for preparing the same

Abstract

The present application provides a heating element for a heating device and a preparation method thereof, and belongs to the technical field of heating devices for heating non-burning cigarettes. The heating element for a heating device includes a silicon carbide ceramic substrate and a ceramic substrate. The ceramic substrate and the ceramic substrate are co-fired and connected, and a circuit layer is sandwiched between the ceramic substrate and the ceramic substrate. The heating element uses a silicon carbide ceramic substrate as the main heat-conducting component, and the thermal conductivity is greater than 50W / mk, so that the heating element heats up faster, the temperature difference in the heating zone is smaller, and the energy consumption is reduced. In addition, due to the lower thermal expansion coefficient and higher bending strength of the silicon carbide material, the thermal shock resistance of the heating element is improved. When the heating element is heating, the inside of the heating element heats outward, which can make the heating of the two surfaces of the heating element more uniform and the heating effect is good.

Description

Technical Field

[0001] The present application relates to the technical field of heating devices for heat-not-burn cigarettes, and in particular to a heating element for a heating device and a preparation method thereof. Background Art

[0002] Heating devices are essential electronic products for smoking heated cigarettes. The heating element, as its core component, is the main source of heat. Therefore, the design of the heating element is the key to influencing the experience of heated cigarettes.

[0003] At present, there are two main types of heat-conducting components in the heating elements of heating devices, one is zirconia material and the other is alumina material. Zirconia has high strength, but the thermal conductivity is only 1-2W / (mk), and the temperature of the heating area is not easy to conduct, making the temperature of the heating area uneven, affecting the heating effect. The thermal conductivity of alumina is about 20W / (mk), the thermal conductivity is not high, and the temperature uniformity is also poor. At the same time, the bending strength is about 260Mpa. Due to the solid structure, the heat melt is large, the heating speed is slow, and the energy consumption is high. Summary of the invention

[0004] The purpose of the present application is to provide a heating element for a heating device and a preparation method thereof, which has a faster heating speed and a smaller temperature difference in the heating zone.

[0005] In a first aspect, the present application provides a heating element for a heating device, comprising a silicon carbide ceramic substrate and a ceramic substrate. The ceramic substrate and the ceramic substrate are co-fired and connected, and a circuit layer is sandwiched between the ceramic substrate and the ceramic substrate.

[0006] The heating element uses a silicon carbide ceramic matrix as the main heat-conducting element. The heating element heats up faster, the temperature difference in the heating area is smaller, and the energy consumption is reduced. In addition, due to the lower thermal expansion coefficient and higher bending strength of the silicon carbide material, the thermal shock resistance of the heating element is improved. When the heating element is heating, the inside of the heating element (circuit layer) heats outward (matrix and substrate), which can make the heating of the two surfaces of the heating element more uniform and the heating effect is good.

[0007] In a possible implementation, the ceramic substrate is an alumina ceramic substrate, a circuit layer is provided on the ceramic substrate, a transition layer is covered on the circuit layer, the circuit layer and the transition layer are both located between the ceramic substrate and the ceramic base, and the transition layer is close to the ceramic base. The expansion coefficient of the transition layer is between the expansion coefficient of the ceramic base and the expansion coefficient of the ceramic substrate.

[0008] The circuit layer is easily formed on the alumina ceramic substrate. A transition layer is set between the ceramic base and the ceramic substrate. When the base and the substrate are combined by co-firing, the shrinkage difference between the silicon carbide material and the alumina material can be buffered, thereby making the combination effect between the base and the substrate better.

[0009] In a possible implementation, the thickness of the ceramic substrate is 0.05-0.2 mm, and the material of the alumina ceramic substrate is: 92-96% alumina, 2-5wt% silicon dioxide, 0.5-3wt% calcium oxide, and 0.5-3wt% magnesium oxide, which can make the laying effect of the circuit layer better, thereby making the heating effect of the heating element better.

[0010] In a possible implementation, the thickness of the transition layer is 0.01-0.1 mm, and the material of the transition layer is: 60-90 wt % aluminum oxide, 5-30 wt % silicon carbide, 1-10 wt % silicon dioxide, and 1-10 wt % calcium oxide.

[0011] The shrinkage difference between the silicon carbide material and the aluminum oxide material can be further reduced, which can make the molding effect of the heating element better.

[0012] In one possible embodiment, the thickness of the ceramic substrate is 0.05-0.2 mm, the ceramic substrate is a silicon carbide ceramic substrate, and the materials of the silicon carbide ceramic substrate and the silicon carbide ceramic matrix are: 60-90wt% silicon carbide, 5-30wt% aluminum oxide, 1-10wt% silicon dioxide, 1-10wt% calcium oxide, and 0.2-5wt% yttrium trioxide.

[0013] The thermal conductivity of silicon carbide material can be made greater than 50W / mk and the bending strength greater than 350Mpa.

[0014] In a possible implementation manner, the ceramic substrate is in a sheet shape, and the ceramic substrate overlaps with the ceramic substrate so that the circuit layer is located between the ceramic substrate and the ceramic substrate.

[0015] The heating element is a sheet-like structure, which can make the heat on the two surfaces of the heating element more uniform.

[0016] In a possible implementation manner, the ceramic substrate is in the shape of a solid needle or a hollow needle, and the ceramic substrate is coated on the surface of the ceramic substrate so that the circuit layer is located between the ceramic substrate and the ceramic substrate.

[0017] The heating element has a columnar structure, the heating element generates heat more evenly, and the temperature difference in the heating area is smaller.

[0018] In a second aspect, the present application provides a method for preparing a heating element for a heating device, comprising the following steps: (1) forming a circuit layer on the surface of a ceramic substrate; (2) pressing the ceramic substrate and a ceramic base body so that the circuit layer is located between the ceramic base body and the ceramic substrate, and then co-firing.

[0019] The ceramic substrate can be used as the basis for carrying the circuit layer. After the ceramic matrix and the ceramic substrate are co-fired, the circuit layer can be firmly connected to the ceramic matrix and the ceramic substrate, and the connection between the ceramic matrix and the ceramic substrate is also more solid. After the circuit layer is heated, the heat is radiated to the two surfaces of the circuit layer (the matrix and the substrate), making the heating element heat more evenly. And the heating element uses a silicon carbide ceramic matrix as the main heating element, so that the heating element heats up faster, the temperature difference in the heating area is smaller, and the energy consumption is reduced. And due to the lower thermal expansion coefficient and higher bending strength of the silicon carbide material, the thermal shock resistance of the heating element is improved.

[0020] In a possible implementation, the ceramic substrate is an alumina ceramic substrate, and after step (1) and before step (2), the method further includes: covering the surface of the circuit layer with a transition layer. In step (2), the circuit layer and the transition layer are both located between the ceramic substrate and the ceramic substrate, and the transition layer is close to the ceramic substrate.

[0021] Since the silicon carbide ceramic matrix and the alumina ceramic substrate are made of different materials, there will be a shrinkage difference when they are co-fired. Therefore, the transition layer between the matrix and the substrate can buffer the shrinkage difference between the silicon carbide material and the alumina material, thereby making the bonding effect between the matrix and the substrate better.

[0022] In a possible implementation manner, the co-firing is performed at 1500-1650° C. This can achieve a better co-firing effect between the substrate and the base sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, without paying any creative work, other related drawings can be obtained based on these drawings and they also belong to the protection scope of the present application.

[0024] Figure 1 A first structural schematic diagram of a heating element for a heating device provided in the present application;

[0025] Figure 2 A first exploded view of a heating element for a heating device provided in the present application;

[0026] Figure 3A second structural schematic diagram of a heating element for a heating device provided in the present application;

[0027] Figure 4 A second exploded view of a heating element for a heating device provided in the present application;

[0028] Figure 5 It is the test position of the heating area in the heating element.

[0029] Icon: 10 - ceramic substrate; 20 - ceramic substrate; 30 - circuit layer; 40 - transition layer; 51 - first electrode; 52 - second electrode; 61 - first lead; 62 - second lead. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0031] Figure 1 A first structural schematic diagram of a heating element for a heating device provided in the present application; Figure 2 A first exploded view of a heating element for a heating device provided in the present application; Figure 3 A second structural schematic diagram of a heating element for a heating device provided in the present application; Figure 4 This is a second exploded view of the heating element for the heating device provided in this application. Figure 1-Figure 4 The heating element for the heating device includes a ceramic substrate 10 and a ceramic substrate 20. The ceramic substrate 10 may be in the form of a sheet or a column. Figure 1 and Figure 2 ), the ceramic substrate 10 is formed by tape casting. The thickness of the sheet-like ceramic substrate 10 is 0.05-0.2 mm to prevent the ceramic substrate 10 from cracking.

[0032] If the ceramic substrate 10 is columnar (such as Figure 3 and Figure 4 ), the ceramic matrix 10 can be solid needle-shaped or hollow needle-shaped, which can make the heating element heat more uniform. Further, the columnar ceramic matrix 10 is formed by hot die casting, injection molding or dry pressing, and then bisque fired to obtain a ceramic matrix 10 with a certain strength. The bisque firing temperature is 1200-1400°C, so as to be co-fired with the ceramic substrate 20 later.

[0033] In the embodiment of the present application, the ceramic substrate 10 is a silicon carbide ceramic substrate 10, that is, the material of the ceramic substrate 10 is mainly silicon carbide. The silicon carbide ceramic substrate 10 serves as the main heat-conducting component, the heating element heats up faster, the temperature difference in the heating zone is smaller, and the energy consumption is reduced. In addition, due to the lower thermal expansion coefficient and higher bending strength of the silicon carbide material, the thermal shock resistance of the heating element is improved.

[0034] Optionally, the material of the silicon carbide ceramic substrate 10 is: 60-90wt% silicon carbide, 5-30wt% aluminum oxide, 1-10wt% silicon dioxide, 1-10wt% calcium oxide, and 0.2-5wt% yttrium trioxide. When the content of silicon carbide is within the above range, the sintering temperature is appropriate, which is conducive to co-firing with the ceramic substrate 20, and the strength of the substrate is higher and the thermal conductivity is better.

[0035] Selecting the above materials as the materials of the silicon carbide ceramic substrate 10 can make the thermal conductivity of the silicon carbide ceramic substrate 10 greater than 50 W / mk and the bending strength greater than 350 MPa.

[0036] In some possible embodiments, the material of the silicon carbide ceramic matrix 10 is: 60wt% silicon carbide, 30wt% aluminum oxide, 4wt% silicon dioxide, 4wt% calcium oxide, and 2wt% yttrium trioxide; or the material of the silicon carbide ceramic matrix 10 is: 90wt% silicon carbide, 5wt% aluminum oxide, 1wt% silicon dioxide, 1wt% calcium oxide, and 3wt% yttrium trioxide; or the material of the silicon carbide ceramic matrix 10 is: 70wt% silicon carbide, 9.8wt% aluminum oxide, 10wt% silicon dioxide, 10wt% calcium oxide, and 0.2wt% yttrium trioxide; or the material of the silicon carbide ceramic matrix 10 is: 66wt% silicon carbide, 15wt% aluminum oxide, 6wt% silicon dioxide, 8wt% calcium oxide, and 5wt% yttrium trioxide.

[0037] In the embodiment of the present application, the thickness of the ceramic substrate 20 is 0.05-0.2 mm. Optionally, the thickness of the ceramic substrate 20 is 0.05 mm, 0.1 mm, 0.15 mm or 0.2 mm.

[0038] Further, the ceramic substrate 20 may be a silicon carbide ceramic substrate 20 or an alumina ceramic substrate 20. If the ceramic substrate 20 is a silicon carbide ceramic substrate 20, the material of the silicon carbide ceramic substrate 20 is substantially the same as the material of the silicon carbide ceramic base 10, and will not be described in detail herein.

[0039] The circuit layer 30 is directly disposed between the silicon carbide ceramic substrate 10 and the silicon carbide ceramic substrate 20. The circuit layer 30 can be first formed on the silicon carbide ceramic substrate 20 and then co-fired between the ceramic substrate 10 and the ceramic substrate 20, or can be first formed on the sheet-shaped ceramic substrate 10 and then co-fired between the ceramic substrate 10 and the ceramic substrate 20.

[0040] Optionally, the material of the circuit layer 30 is a mixture of one or more of tungsten, molybdenum and ruthenium. The thickness of the circuit layer 30 is 10-25 μm. In some possible implementations, the thickness of the circuit layer 30 is 10 μm, 15 μm, 20 μm or 25 μm.

[0041] If the ceramic substrate 20 is an alumina ceramic substrate 20 , the circuit layer 30 is first formed on the alumina ceramic substrate 20 and then co-fired between the ceramic base 10 and the ceramic substrate 20 , so that the printing effect of the circuit layer 30 is better.

[0042] Optionally, the ceramic substrate 20 is an alumina ceramic substrate 20, that is, the material of the ceramic substrate 20 is mainly alumina, and the material of the alumina ceramic substrate 20 is: 92-96% aluminum oxide, 2-5wt% silicon dioxide, 0.5-3wt% calcium oxide, and 0.5-3wt% magnesium oxide.

[0043] In some possible embodiments, the material of the alumina ceramic substrate 20 is: 92% alumina, 5wt% silica, 2wt% calcium oxide, and 1wt% magnesium oxide; or the material of the alumina ceramic substrate 20 is: 96% alumina, 2wt% silica, 0.5wt% calcium oxide, and 1.5% magnesium oxide; or the material of the alumina ceramic substrate 20 is: 92% alumina, 2wt% silica, 3wt% calcium oxide, and 3wt% magnesium oxide; or the material of the alumina ceramic substrate 20 is: 95% alumina, 4wt% silica, 0.5wt% calcium oxide, and 0.5% magnesium oxide.

[0044] Since the alumina ceramic substrate 20 and the silicon carbide ceramic substrate 10 are made of different materials, there is a certain difference in the thermal expansion coefficients of the two. When the alumina ceramic substrate 20 and the silicon carbide ceramic substrate 10 are co-fired, there is a difference in the shrinkage between the two. Therefore, a circuit layer 30 is provided on the ceramic substrate 20, and a transition layer 40 is covered on the circuit layer 30. The circuit layer 30 and the transition layer 40 are both located between the ceramic substrate 20 and the ceramic substrate 10, and the transition layer 40 is close to the ceramic substrate 10. Among them, the expansion coefficient of the transition layer 40 is between the expansion coefficient of the ceramic substrate 10 and the expansion coefficient of the ceramic substrate 20.

[0045] The setting of the transition layer 40 can buffer the shrinkage difference between the alumina ceramic substrate 20 and the silicon carbide ceramic substrate 10, strengthen the bonding between the ceramic substrate 10 and the ceramic substrate 20, and enable the heat generated by the circuit layer 30 to be better transferred to the silicon carbide ceramic substrate 10, resulting in a better heating effect.

[0046] Optionally, the thickness of the transition layer 40 is 0.01-0.1 mm. In some possible implementations, the thickness of the transition layer 40 is 0.01 mm, 0.03 mm, 0.05 mm, 0.08 mm or 0.1 mm.

[0047] In this embodiment, the materials of the transition layer 40 are: 60-90wt% of aluminum oxide, 5-30wt% of silicon carbide, 1-10wt% of silicon dioxide and 1-10wt% of calcium oxide. The content of aluminum oxide in the transition layer 40 is between the content of aluminum oxide in the silicon carbide ceramic matrix 10 and the content of aluminum oxide in the aluminum oxide ceramic substrate 20; the content of silicon carbide in the transition layer 40 is between the content of silicon carbide in the silicon carbide ceramic matrix 10 and the content of silicon carbide in the aluminum oxide ceramic substrate 20. Therefore, the expansion coefficient of the transition layer 40 can be between the expansion coefficient of the ceramic matrix 10 and the expansion coefficient of the ceramic substrate 20.

[0048] In some possible embodiments, the material of the transition layer 40 is: 60wt% aluminum oxide, 30wt% silicon carbide, 5wt% silicon dioxide and 5wt% calcium oxide; or the material of the transition layer 40 is: 90wt% aluminum oxide, 5wt% silicon carbide, 1wt% silicon dioxide and 4wt% calcium oxide; or the material of the transition layer 40 is: 80wt% aluminum oxide, 10wt% silicon carbide, 9wt% silicon dioxide and 1wt% calcium oxide; or the material of the transition layer 40 is: 70wt% aluminum oxide, 10wt% silicon carbide, 10wt% silicon dioxide and 10wt% calcium oxide.

[0049] In the embodiment of the present application, if the ceramic substrate 10 is a sheet structure, the ceramic substrate 10 overlaps with the ceramic substrate 20 so that the circuit layer 30 is located between the ceramic substrate 10 and the ceramic substrate 20 .

[0050] If the ceramic substrate 10 is a columnar structure (solid needle-shaped or hollow needle-shaped), the ceramic substrate 20 is coated on the surface of the ceramic substrate 10 so that the circuit layer 30 is located between the ceramic substrate 10 and the ceramic substrate 20 .

[0051] In the embodiment of the present application, a first electrode 51 and a second electrode 52 are further disposed on a surface of the ceramic substrate 20 facing away from the circuit layer 30 , and both the first electrode 51 and the second electrode 52 are electrically connected to the circuit layer 30 .

[0052] Furthermore, a first through hole and a second through hole are provided on the ceramic substrate 20 , the first electrode 51 passes through the first through hole to be electrically connected to the circuit layer 30 , and the second electrode 52 passes through the second through hole to be electrically connected to the circuit layer 30 .

[0053] Optionally, the first electrode 51 and the second electrode 52 are first printed on the back of the ceramic substrate 20, and a first through hole and a second through hole are opened on the ceramic substrate 20, and the first electrode 51 is connected to the circuit layer 30 through the first through hole, and the second electrode 52 is connected to the circuit layer 30 through the second through hole, so that the circuit layer 30 is energized.

[0054] In this embodiment, a first lead 61 is provided at one end of the first electrode 51 away from the ceramic substrate 20, and a second lead 62 is provided at one end of the second electrode 52 away from the ceramic substrate 20. The first lead 61 is connected to the positive electrode of the power supply, and the second lead 62 is connected to the negative electrode of the power supply, so as to communicate with the external power supply.

[0055] Optionally, the lead brazing solder of the first lead 61 and the second lead 62 is silver or silver-copper solder so as to energize the electrodes.

[0056] The present application provides a method for preparing a heating element for a heating device, comprising the following steps: (1) forming a circuit layer 30 on the surface of a ceramic substrate 20. (2) pressing the ceramic substrate 20 and the ceramic base 10 so that the circuit layer 30 is located between the ceramic base 10 and the ceramic substrate 20, and then co-firing.

[0057] Optionally, the co-firing is performed at 1500-1650° C. In some possible implementations, the co-firing is performed at 1500° C., 1550° C., 1600° C. or 1650° C.

[0058] If the ceramic substrate 20 is an alumina ceramic substrate 20 , the transition layer 40 is firstly covered on the surface of the circuit layer 30 , and then co-fired, so that the bonding effect between the ceramic base 10 and the ceramic substrate 20 can be better.

[0059] The heating element with the above structure prepared by the above preparation method can be used as a heating element of a heating device to obtain a heating device with better heating effect, so as to heat non-combustion cigarettes.

[0060] Example 1

[0061] A method for preparing a heating element for a heating device comprises the following steps:

[0062] (1) Silicon carbide ceramic powder (materials: 70wt% silicon carbide, 9.8wt% aluminum oxide, 10wt% silicon dioxide, 10wt% calcium oxide, 0.2wt% yttrium trioxide) is hot-die-casted to obtain a hollow needle-shaped ceramic matrix 10, which is then bisque-fired at 1200-1400°C to obtain a ceramic matrix 10 with a certain strength.

[0063] (2) Cut the alumina cast sheet (material: 96% alumina, 2wt% silica, 0.5wt% calcium oxide, 1.5wt% magnesium oxide) into alumina ceramic substrates 20 with a thickness of 0.1 mm.

[0064] (3) A resistance circuit (circuit layer 30, made of tungsten paste) is printed on the surface of the ceramic substrate 20, and the thickness of the circuit layer 30 is 20 μm.

[0065] (4) After the circuit layer 30 is dried, a transition layer 40 (material: 60wt% aluminum oxide, 30wt% silicon carbide, 5wt% silicon dioxide and 5wt% calcium oxide) is printed.

[0066] (5) Print the first electrode 51 and the second electrode 52 on the surface of the ceramic substrate 20 facing away from the circuit layer 30, and open a first through hole and a second through hole on the ceramic substrate 20, so that the first electrode 51 is electrically connected to the circuit layer 30 through the first through hole, and the second electrode 52 is electrically connected to the circuit layer 30 through the second through hole.

[0067] (6) The ceramic substrate 20 printed with the transition layer 40 is wound on the ceramic base 10 and then isostatically pressed.

[0068] (7) Sinter the pressed product at 1550°C to obtain a semi-finished product.

[0069] (8) The semi-finished product is brazed with silver solder at 1000°C to obtain a heating element for a heating device.

[0070] Example 2

[0071] A method for preparing a heating element for a heating device comprises the following steps:

[0072] (1) Silicon carbide ceramic powder (materials: 70wt% silicon carbide, 9.8wt% aluminum oxide, 10wt% silicon dioxide, 10wt% calcium oxide, 0.2wt% yttrium trioxide) is tape-cast to obtain a sheet of silicon carbide cast sheet. The silicon carbide cast sheet is cut into a silicon carbide ceramic substrate 10 with a thickness of 0.1 mm.

[0073] (2) Cut the alumina cast sheet (material: 96% alumina, 2wt% silica, 0.5wt% calcium oxide, 1.5wt% magnesium oxide) into alumina ceramic substrates 20 with a thickness of 0.1 mm.

[0074] (3) A resistance circuit (circuit layer 30, made of tungsten paste) is printed on the surface of the ceramic substrate 20, and the thickness of the circuit layer 30 is 20 μm.

[0075] (4) After the circuit layer 30 is dried, a transition layer 40 (material: 60wt% aluminum oxide, 30wt% silicon carbide, 5wt% silicon dioxide and 5wt% calcium oxide) is printed.

[0076] (5) Print the first electrode 51 and the second electrode 52 on the surface of the ceramic substrate 20 facing away from the circuit layer 30, and open a first through hole and a second through hole on the ceramic substrate 20, so that the first electrode 51 is electrically connected to the circuit layer 30 through the first through hole, and the second electrode 52 is electrically connected to the circuit layer 30 through the second through hole.

[0077] (6) The ceramic substrate 20 printed with the transition layer 40 is wound on the ceramic base 10 and then isostatically pressed.

[0078] (7) Sinter the pressed product at 1550°C to obtain a semi-finished product.

[0079] (8) The semi-finished product is brazed with silver solder at 1000°C to obtain a heating element for a heating device.

[0080] Example 3

[0081] A method for preparing a heating element for a heating device comprises the following steps:

[0082] (1) Silicon carbide ceramic powder (materials: 70wt% silicon carbide, 9.8wt% aluminum oxide, 10wt% silicon dioxide, 10wt% calcium oxide, 0.2wt% yttrium trioxide) is hot-die-casted to obtain a hollow needle-shaped ceramic matrix 10, which is then bisque-fired at 1200-1400°C to obtain a ceramic matrix 10 with a certain strength.

[0083] (2) Cut the silicon carbide cast sheet (material: 70wt% silicon carbide, 9.8wt% aluminum oxide, 10wt% silicon dioxide, 10wt% calcium oxide, 0.2wt% yttrium trioxide) into an alumina ceramic substrate 20 with a thickness of 0.1mm.

[0084] (3) A resistance circuit (circuit layer 30, made of tungsten paste) is printed on the surface of the ceramic substrate 20, and the thickness of the circuit layer 30 is 20 μm.

[0085] (4) Print the first electrode 51 and the second electrode 52 on the surface of the ceramic substrate 20 facing away from the circuit layer 30, and open a first through hole and a second through hole on the ceramic substrate 20, so that the first electrode 51 is electrically connected to the circuit layer 30 through the first through hole, and the second electrode 52 is electrically connected to the circuit layer 30 through the second through hole.

[0086] (5) The ceramic substrate 20 printed with the circuit layer 30 is wound on the ceramic base 10 and then isostatically pressed.

[0087] (6) Sinter the pressed product at 1550°C to obtain a semi-finished product.

[0088] (7) The semi-finished product is brazed with silver solder at 1000°C to obtain a heating element for a heating device.

[0089] Example 4

[0090] A method for preparing a heating element for a heating device comprises the following steps:

[0091] (1) Silicon carbide ceramic powder (materials: 70wt% silicon carbide, 9.8wt% aluminum oxide, 10wt% silicon dioxide, 10wt% calcium oxide, 0.2wt% yttrium trioxide) is tape-cast to obtain a sheet of silicon carbide cast sheet. The silicon carbide cast sheet is cut into a silicon carbide ceramic substrate 10 with a thickness of 0.1 mm.

[0092] (2) Cut the silicon carbide cast sheet into silicon carbide ceramic substrates 20 with a thickness of 0.1 mm.

[0093] (3) A resistance circuit (circuit layer 30, made of tungsten paste) is printed on the surface of the ceramic substrate 20, and the thickness of the circuit layer 30 is 20 μm.

[0094] (4) Print the first electrode 51 and the second electrode 52 on the surface of the ceramic substrate 20 facing away from the circuit layer 30, and open a first through hole and a second through hole on the ceramic substrate 20, so that the first electrode 51 is electrically connected to the circuit layer 30 through the first through hole, and the second electrode 52 is electrically connected to the circuit layer 30 through the second through hole.

[0095] (5) The ceramic substrate 20 printed with the circuit layer 30 is wound on the ceramic base 10 and then isostatically pressed.

[0096] (6) Sinter the pressed product at 1550°C to obtain a semi-finished product.

[0097] (7) The semi-finished product is brazed with silver solder at 1000°C to obtain a heating element for a heating device.

[0098] Comparative Example 1

[0099] A method for preparing a heating element for a heating device comprises the following steps:

[0100] (1) Alumina ceramic powder (materials: 96% alumina, 2wt% silica, 0.5wt% calcium oxide, 1.5% magnesium oxide) is hot-die-casted to obtain a hollow needle-shaped ceramic matrix, which is then bisque-fired at 1200-1400°C to obtain a ceramic matrix with a certain strength.

[0101] (2) Cut the alumina cast sheet (material: 96% alumina, 2wt% silicon dioxide, 0.5wt% calcium oxide, 1.5wt% magnesium oxide) into alumina ceramic substrates with a thickness of 0.1 mm.

[0102] (3) Print a resistor circuit (circuit layer, made of tungsten paste) on the surface of the ceramic substrate, and the thickness of the circuit layer is 20 μm.

[0103] (4) Print the first electrode and the second electrode on the surface of the ceramic substrate away from the circuit layer, and open the first through hole and the second through hole on the ceramic substrate, so that the first electrode is electrically connected to the circuit layer through the first through hole, and the second electrode 52 is electrically connected to the circuit layer through the second through hole.

[0104] (5) Winding the ceramic substrate printed with the circuit layer on the ceramic substrate, and then isostatically pressing.

[0105] (6) Sinter the pressed product at 1550°C to obtain a semi-finished product.

[0106] (7) The semi-finished product is brazed with silver solder at 1000°C to obtain a heating element for a heating device.

[0107] Comparative Example 2

[0108] A method for preparing a heating element for a heating device comprises the following steps:

[0109] (1) Alumina ceramic powder (materials: 96% alumina, 2wt% silicon dioxide, 0.5wt% calcium oxide, 1.5% magnesium oxide) is tape-cast to obtain a sheet of alumina cast sheet. The alumina cast sheet is cut into alumina ceramic substrates with a thickness of 0.1 mm.

[0110] (2) Cut the alumina cast sheet (material: 96% alumina, 2wt% silicon dioxide, 0.5wt% calcium oxide, 1.5wt% magnesium oxide) into alumina ceramic substrates with a thickness of 0.1 mm.

[0111] (3) Print a resistor circuit (circuit layer, made of tungsten paste) on the surface of the ceramic substrate, and the thickness of the circuit layer is 20 μm.

[0112] (4) Print the first electrode and the second electrode on the surface of the ceramic substrate away from the circuit layer, and open the first through hole and the second through hole on the ceramic substrate, so that the first electrode is electrically connected to the circuit layer through the first through hole, and the second electrode 52 is electrically connected to the circuit layer through the second through hole.

[0113] (5) Winding the ceramic substrate printed with the circuit layer on the ceramic substrate, and then isostatically pressing.

[0114] (6) Sinter the pressed product at 1550°C to obtain a semi-finished product.

[0115] (7) The semi-finished product is brazed with silver solder at 1000°C to obtain a heating element for a heating device.

[0116] Experimental example

[0117] 1. Temperature uniformity

[0118] Figure 5 For test locations of the heating element’s hot zone, refer to Figure 5 ,Test conditions: When power is on, the temperature of the center point of the heating zone of the heating element reaches 350°C, and the boundary temperature of the heating zone and the temperature of the center zone are tested. Among them, the boundary point is 3mm axially away from the center point, and the structure is shown in Table 1.

[0119] Table 1 Temperature uniformity results of heating elements

[0120] Serial number Product Type Boundary 1 Center Point Boundary 2 Temperature difference Remark Example 1 Silicon carbide material 345 350 346 5 excellent Example 2 Silicon carbide material 344 350 345 6 excellent Example 3 Silicon carbide material 346 350 348 4 excellent Example 4 Silicon carbide material 348 350 347 3 excellent Comparative Example 1 Alumina material 342 350 339 11 medium Comparative Example 2 Alumina material 337 350 335 15 medium

[0121] As can be seen from Table 1, when silicon carbide is selected as the main material of the ceramic matrix, the temperature difference generated when the heating element is heated is smaller, indicating that the heating element heats more evenly.

[0122] 2. Warm-up time test

[0123] Under the conditions of 3.2V voltage and 0.9Ω resistance, the time when the surface temperature of the product boundary 1 reaches 350°C is recorded to obtain Table 2.

[0124] Table 2 Test results of preheating specimens of heating elements

[0125] Serial number Product Type temperature time Remark Example 1 Silicon carbide material 350 10s quick Example 2 Silicon carbide material 350 11s quick Example 3 Silicon carbide material 350 9s quick Example 4 Silicon carbide material 350 10s quick Comparative Example 1 Alumina material 350 15s slow Comparative Example 2 Alumina material 350 17s slow

[0126] It can be seen from Table 2 that when silicon carbide is selected as the main material of the ceramic matrix, the time used for preheating the heating element to 350°C is shorter, indicating that the preheating time of the heating element is shorter.

[0127] The above is only a part of the embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A heating element for a heating device, characterized in that: It includes a silicon carbide ceramic substrate and a ceramic substrate; The ceramic substrate is co-fired and connected with the ceramic substrate, and a circuit layer is sandwiched between the ceramic substrate and the ceramic substrate; the material of the silicon carbide ceramic substrate is: 60-90 wt% of silicon carbide, 5-30 wt% of aluminum oxide, 1-10 wt% of silicon dioxide, 1-10 wt% of calcium oxide, and 0.2-5 wt% of yttrium trioxide; the thermal conductivity of the silicon carbide ceramic substrate is greater than 50W / mk, and the bending strength is greater than 350Mpa; The ceramic substrate is an alumina ceramic substrate, the circuit layer is arranged on the ceramic substrate, the circuit layer is covered with a transition layer, the circuit layer and the transition layer are both located between the ceramic substrate and the ceramic base, and the transition layer is close to the ceramic base; wherein the expansion coefficient of the transition layer is between the expansion coefficient of the ceramic base and the expansion coefficient of the ceramic substrate; the thickness of the ceramic substrate is 0.05-0.2mm, and the material of the alumina ceramic substrate is: 92-96% aluminum oxide, 2-5 wt% silicon dioxide, 0.5-3 wt% calcium oxide, and 0.5-3 wt% magnesium oxide; Alternatively, the thickness of the ceramic substrate is 0.05-0.2 mm, the ceramic substrate is a silicon carbide ceramic substrate, and the material of the silicon carbide ceramic substrate is: 60-90 wt% silicon carbide, 5-30 wt% aluminum oxide, 1-10 wt% silicon dioxide, 1-10wt% calcium oxide, and 0.2-5 wt% yttrium trioxide.

2. The heating element according to claim 1, characterized in that The thickness of the transition layer is 0.01-0.1 mm, and the material of the transition layer is: 60-90wt% of aluminum oxide, 5-30wt% of silicon carbide, 1-10wt% of silicon dioxide and 1-10wt% of calcium oxide.

3. The heating element according to claim 1 or 2, characterized in that The ceramic substrate is in sheet shape, and the ceramic substrate overlaps with the ceramic substrate so that the circuit layer is located between the ceramic substrate and the ceramic substrate.

4. The heating element according to claim 1 or 2, characterized in that The ceramic substrate is in the shape of a solid needle or a hollow needle, and the ceramic substrate is coated on the surface of the ceramic substrate so that the circuit layer is located between the ceramic substrate and the ceramic substrate.

5. A method for preparing a heating element for a heating device according to any one of claims 1 to 4, characterized in that: The steps include: (1) forming the circuit layer on the surface of the ceramic substrate; (2) Pressing the ceramic substrate and the ceramic base body together so that the circuit layer is located between the ceramic base body and the ceramic substrate, and then co-firing.

6. The preparation method according to claim 5, characterized in that: The ceramic substrate is an alumina ceramic substrate. After step (1) and before step (2), the method further comprises: covering a transition layer on the surface of the circuit layer; In the step (2), the circuit layer and the transition layer are both located between the ceramic substrate and the ceramic substrate, and the transition layer is close to the ceramic substrate.

7. The preparation method according to claim 5 or 6, characterized in that: The co-firing is carried out at 1500-1650°C.

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