Heating element assembly, preparation method and application thereof

Abstract

The present invention discloses a heating element assembly, a preparation method thereof, and an application thereof. The heating element assembly comprises: a first inorganic layer and a second inorganic layer, a heating layer and an adhesive layer being sandwiched between the first inorganic layer and the second inorganic layer, wherein one side of the heating layer is connected to the first inorganic layer, and the other side is connected to the second inorganic layer through the adhesive layer, and the heating layer and the adhesive layer are embedded and connected to each other. Compared with the prior art, the heating element assembly not only has better one-way thermal conductivity and anti-fragmentation ability during use, and is safer, but also has a strong bonding force between the heating layer and the second inorganic layer, and good durability. It can be widely used in products such as heatable pots, inner pots of cooking utensils, or electric kettles.

Description

Technical Field

[0001] The present invention belongs to the field of household electrical appliances, and in particular, relates to a heating element assembly, a preparation method and an application thereof. Background Art

[0002] Cookware incorporates numerous inorganic materials, such as ceramics and glass. Examples include the ceramic linings of electric stew pots, glass kettles with glass linings, and the microcrystalline and ceramic pots used in induction cookers. While glass-ceramics and other materials offer excellent chemical resistance and are considered healthy and environmentally friendly, these inorganic materials also have numerous drawbacks, such as low heat transfer efficiency, poor toughness, and brittleness. Therefore, further improvements are needed in glass-ceramics and other materials for cooking. Summary of the Invention

[0003] The present invention is mainly proposed based on the following problems:

[0004] Conventional solutions for heating glassware primarily utilize heating elements such as heating tubes and heating plates, with the glassware contacting the heating plate and heating tube for heat transfer. This approach offers a simple overall assembly, but presents significant challenges, such as a small contact area, making close contact difficult, and low heat transfer efficiency. For applications such as kettles, heating 1L of water can take over 15 minutes. While some manufacturers have improved this technology to improve thermal efficiency, the benefits have been minimal. Furthermore, some manufacturers have adopted solutions such as thick-film heating, where thick-film circuits are printed on the glass for heating. This approach offers high thermal efficiency and uniform heating, but places high demands on the glass, such as heat-resistant quartz glass, and also presents safety concerns. The high current draw in the event of glass breakage poses a significant safety risk to consumers. Similar solutions include printed tin oxide and thermally sprayed heating wires. Recently, some manufacturers have adopted the practice of printing or thermally transferring a metallic magnetic film on the outside of the glass, heating it through electromagnetic heating. While this metal film offers high heating efficiency and no safety issues, it also presents challenges such as high stress during heating, high thermal resistance, low heat transfer efficiency, and the high stress that can easily lead to glass breakage.

[0005] In addition, when glassware is prepared using the float process, one side of the glass is a tin surface, and metallic tin remains in the glass. If the tin surface is in direct contact with a conductive metal surface (such as silver), a galvanic cell reaction will form at the interface during long-term aging, causing the interface bonding to deteriorate significantly.

[0006] The present invention aims to at least partially address one of the technical problems in the related art. To this end, one object of the present invention is to provide a heating element assembly, a preparation method, and an application thereof to improve the heat transfer efficiency, anti-fragmentation capability, safety, and durability of products such as cooking utensils.

[0007] According to a first aspect of the present invention, a heating element assembly is provided. According to an embodiment of the present invention, the heating element assembly comprises: a first inorganic layer and a second inorganic layer, wherein a heating layer and an adhesive layer are sandwiched between the first inorganic layer and the second inorganic layer, wherein one side of the heating layer is connected to the first inorganic layer and the other side is connected to the second inorganic layer via the adhesive layer, and the heating layer and the adhesive layer are embedded and connected to each other.

[0008] The inventors have discovered that by forming an adhesive layer that is embedded and connected to the heating layer between the heating layer and the second inorganic layer, on the one hand, the thermal resistance between the heating layer and the second inorganic layer can be increased, and more heat from the heating layer can be transferred to the first inorganic layer; on the other hand, the structure in which the heating layer and the adhesive layer are embedded and connected to each other can further improve the bonding strength between the heating layer and the second inorganic layer, while improving the uniformity of heat transfer from the heating layer to the adhesive layer and reducing the risk of heat concentration in the adhesive layer, which can further help improve the bonding force between the adhesive layer and the heating layer; on the other hand, a suitable adhesive layer can be selected according to the material of the second inorganic layer. The material can be used to improve the bonding strength between the bonding layer and the second inorganic layer. For example, when the second inorganic layer is a glass layer, a bonding layer with a glass phase can be provided between the heating layer and the second inorganic layer to avoid direct contact between the heating layer and the glass tin surface. In particular, when the heating layer is heated by a metal material, it is also preferred that the bonding layer does not contain metal elements. This can avoid the problem that the bonding strength of the heating layer and the second inorganic layer is greatly deteriorated due to the formation of a primary battery reaction at the interface during long-term aging, and the resulting deterioration in the bonding strength, which leads to the deterioration of the cold and heat shock resistance of the second inorganic layer, and the problem of easy deformation or cracking during heating or use. Therefore, compared with the prior art, the heating element assembly of the above embodiment of the present invention not only has an advantageous heat conduction direction during use, but also has better anti-fragmentation ability and higher safety. In addition, the bonding force between the heating layer and the second inorganic layer is strong and durable, and can be widely used in products such as heated pots, inner pots of cooking utensils or electric kettles.

[0009] In addition, the heating element assembly according to the above embodiment of the present invention may also have the following additional technical features:

[0010] In some embodiments of the present invention, a glass phase is formed in both the heating layer and the bonding layer, and the glass phase in the heating layer and the glass phase in the bonding layer are connected to each other.

[0011] In some embodiments of the present invention, the melting temperature of the bonding layer is not higher than the melting temperature of the heating layer.

[0012] In some embodiments of the present invention, a glass phase is formed in the heating layer, the melting temperature of the glass phase in the heating layer is greater than the melting temperature of the bonding layer, and the melting temperature of the glass phase in the heating layer is not higher than 800°C.

[0013] In some embodiments of the present invention, the glass phase in the bonding layer is formed by a first inorganic oxide, and the glass phase in the heating layer is formed by a second inorganic oxide. Both the first inorganic oxide and the second inorganic oxide include silicon oxide compounds. In a unit area cross-section, the content of silicon in the bonding layer is less than the content of silicon in the heating layer.

[0014] In some embodiments of the present invention, at least one of the following conditions is met: the first inorganic oxide includes 30 to 60 wt% bismuth oxide and 10 to 40 wt% silicon oxide; the second inorganic oxide includes silicon oxide, and the proportion of the second inorganic oxide in the heating layer is 10 to 30 wt%; the first inorganic oxide and the second inorganic oxide independently include at least one selected from aluminum oxide, boron oxide, titanium oxide, zinc oxide, chromium oxide, and lithium oxide.

[0015] In some embodiments of the present invention, the heating element assembly satisfies at least one of the following conditions: the thickness of the heating layer is not greater than the thickness of the bonding layer; the orthographic projection of the heating layer on the bonding layer is located inside the bonding layer; a glass phase is formed in both the heating layer and the bonding layer, and in at least a portion of the heating element assembly, the first inorganic layer and the second inorganic layer are connected through the glass phase in the heating layer and the glass phase in the bonding layer; the connection interface between the bonding layer and the second inorganic layer is a relatively flat surface.

[0016] In some embodiments of the present invention, the thickness of the heating layer is 10 to 25 μm, and the thickness of the adhesive layer is 10 to 45 μm.

[0017] In some embodiments of the present invention, the heating element assembly satisfies at least one of the following conditions: the first inorganic layer and the second inorganic layer are arranged relative to each other; the thickness of the first inorganic layer is not greater than the thickness of the second inorganic layer; the first inorganic layer and the second inorganic layer are independently glass layers, ceramic layers or microcrystalline glass plates; the heating layer and the first inorganic layer are connected by a transition layer.

[0018] In some embodiments of the present invention, the heating element assembly satisfies at least one of the following conditions: the transition layer is interpenetrated and bonded with the first inorganic layer and the heating layer; the heating layer contains metal elements, the content of the metal elements in the transition layer is greater than or equal to 0, and the content of the metal elements in the heating layer is greater than the content of the metal elements in the transition layer per unit area cross section; the heating layer and the transition layer both contain silicon oxides, and the silicon content in the heating layer is less than the silicon content in the transition layer per unit area cross section; the heating layer, the transition layer and the bonding layer all contain silicon oxides, and the silicon content in the heating layer is less than the silicon content in the transition layer per unit area cross section, and the silicon content in the bonding layer is greater than the silicon content in the transition layer; a glass phase is formed in the transition layer, the melting temperature of the glass phase in the bonding layer is not greater than the melting temperature of the glass phase in the transition layer, and the melting temperature of the glass phase in the transition layer is not higher than 800°C; the thickness of the transition layer is not greater than the thickness of the heating layer; the orthographic projection of the heating layer on the transition layer is located inside the transition layer.

[0019] In some embodiments of the present invention, the heating element assembly satisfies at least one of the following conditions: the metal elements in the transition layer and the heating layer are of the same type, and the glass phases in the transition layer and the heating layer are of the same type; the heating layer includes no less than 70 wt% of metal elements; the heating layer includes magnetically sensible metal elements with a relative magnetic permeability less than 1; the metal elements include at least one selected from silver, copper and aluminum; the thickness of the transition layer is 0.1 to 5 μm.

[0020] According to a second aspect of the present invention, the present invention provides a method for preparing the above-mentioned heating element assembly. According to an embodiment of the present invention, the method comprises:

[0021] (1) forming a heating layer on the first inorganic layer using a heating layer slurry, and forming a bonding layer on the heating layer using a bonding layer slurry;

[0022] (2) Sintering the first inorganic layer formed with the heating layer and the bonding layer and the second inorganic layer so that the first inorganic layer and the second inorganic layer are bonded to each other, thereby obtaining the heating element assembly.

[0023] According to the method for preparing a heating element assembly of the above embodiment of the present invention: by forming an adhesive layer that is embedded and connected to the heating layer between the heating layer and the second inorganic layer, on the one hand, the thermal resistance between the heating layer and the second inorganic layer can be increased, and the heat of the heating layer can be promoted to be transferred more to the first inorganic layer; on the other hand, the mutual embedding connection of the heating layer and the adhesive layer can be achieved by sintering, which can not only further improve the bonding strength between the heating layer and the second inorganic layer, but also improve the uniformity of the heat transfer from the heating layer to the adhesive layer, and reduce the risk of heat concentration in the adhesive layer, which can further help to improve the bonding force between the adhesive layer and the heating layer; on the other hand, according to the second inorganic layer The material of the adhesive layer is selected to improve the bonding strength of the adhesive layer and the second inorganic layer. For example, when the second inorganic layer is a glass layer, an adhesive layer with a glass phase can be provided between the heating layer and the second inorganic layer to avoid direct contact between the heating layer and the glass tin surface. In particular, when the heating layer is heated by a metal material, it is also preferred that the adhesive layer does not contain metal elements. This can avoid the problem that the bonding strength of the heating layer and the second inorganic layer is greatly deteriorated due to the formation of a primary battery reaction at the interface during long-term aging, and the resulting deterioration in the bonding strength, which leads to the deterioration of the cold and heat shock resistance of the second inorganic layer, and the problem of easy deformation or cracking during heating or use. Compared with the prior art, the heating element assembly prepared by this method not only has an advantageous heat conduction direction during use, but also has better anti-fragmentation ability and higher safety. In addition, the bonding force between the heating layer and the second inorganic layer is strong and durable, and can be widely used in products such as heated pots, inner pots of cooking utensils or electric kettles.

[0024] In some embodiments of the present invention, step (1) further includes: (1-1) printing the heating layer slurry on the first inorganic layer and drying or sintering it; (1-2) printing the bonding layer slurry on the heating layer obtained by drying or sintering it, and sintering it.

[0025] In some embodiments of the present invention, the sintering temperatures in step (1) and step (2) are independently 550-650°C.

[0026] In some embodiments of the present invention, before performing step (1), the method further includes: printing a transition layer slurry on the first inorganic layer and drying or sintering it; in step (1), forming the heating layer on the transition layer obtained by drying or sintering.

[0027] According to a third aspect of the present invention, a heatable dish is provided. According to an embodiment of the present invention, the heatable dish comprises the aforementioned heating element assembly or a heating element assembly produced using the aforementioned method for producing a heating element assembly. Compared to existing technologies, the heatable dish exhibits an advantageous heat conduction direction during heating, is less susceptible to breakage, and exhibits high safety, good thermal stability, and a longer service life.

[0028] In some embodiments of the present invention, the heatable dish satisfies at least one of the following conditions: the heating element assembly is disposed at the bottom of the heatable dish; the heatable dish comprises a side wall and a bottom wall that are sealed together, and at least a portion of the bottom wall is the heating element assembly; the heatable dish is made of glass-ceramic, borosilicate glass, or ceramic.

[0029] In some embodiments of the present invention, the side wall and the bottom wall define a cavity for the heatable vessel, and an average thickness of the heating element assembly is smaller than an average thickness of the side wall.

[0030] In some embodiments of the present invention, the heating element assembly is connected to the side wall by fusion welding, and the fusion welding is achieved by the following steps: (i) preheating the heating element assembly; (ii) welding the preheated edge of the heating element assembly and the side wall using a heat source; and (iii) annealing the welded vessel.

[0031] In some embodiments of the present invention, the preheating temperature is 300-600°C, and the annealing temperature is 500-700°C.

[0032] According to a fourth aspect of the present invention, an electrical appliance is provided. According to an embodiment of the present invention, the electrical appliance includes the aforementioned heatable dish. Compared to existing technologies, the electrical appliance has the advantages of reduced safety hazards and a longer service life, thereby further improving customer satisfaction.

[0033] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which:

[0035] Figure 1 Schematic diagram of the structure of a heating element assembly according to one embodiment of the present invention.

[0036] Figure 2 2 is a schematic structural diagram of a heating element assembly according to another embodiment of the present invention.

[0037] Figure 3 It is a flow chart of a method for preparing a heating element assembly according to one embodiment of the present invention.

[0038] Figure 4 2 is a schematic structural diagram of a heatable kettle body according to an embodiment of the present invention.

[0039] Figure 5 Schematic diagram of lead bending during bonding strength testing in the embodiments of the present invention and the comparative example.

[0040] Figure 6 Schematic diagram of the local microstructure of a heating element assembly according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0042] In the description of the present invention, it should be understood that the terms "thickness", "upper", "lower", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "multiple" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0043] In the present invention, unless otherwise specified or limited, terms such as "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0044] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0045] According to the first aspect of the present invention, the present invention provides a heating element assembly. According to an embodiment of the present invention, Figure 1 As shown, the heating element assembly includes: a first inorganic layer 10 and a second inorganic layer 20, a heating layer 30 and a bonding layer 40 are sandwiched between the first inorganic layer 10 and the second inorganic layer 20, wherein one side of the heating layer 30 is connected to the first inorganic layer 10, and the other side is connected to the second inorganic layer 20 through the bonding layer 40, and the heating layer 40 and the bonding layer 30 are embedded and connected to each other (for example, you can refer to Figure 6 It is understood that the heating layer 30 and the bonding layer 40 are in a mutually embedded and connected structure). The heating element assembly not only has an advantageous heat conduction direction during use, but also has better anti-fragmentation ability and higher safety. In addition, the heating layer and the second inorganic layer have strong bonding strength and good durability. It can be widely used in products such as heatable pots, inner pots of cooking utensils or electric kettles. Among them, when the heating element assembly is used in products such as pots (inner pots) or electric kettles, the first inorganic layer can be in contact with the food or water to be heated, and the second inorganic layer can be used to achieve a certain heat insulation effect. It should be noted that although the heating element assembly of the present invention can increase the thermal resistance between the heating layer and the second inorganic layer by providing the bonding layer, thereby improving the transfer of heat to the first inorganic layer, when the heating element assembly is used in products such as pots (inner pots) or electric kettles, the heat is higher and the transfer speed is faster, resulting in greater noise when cooking food or water. Compared with the structure without the first inorganic layer, the addition of the first inorganic layer in the present invention can appropriately reduce the heat transfer speed to the food to be cooked, thereby significantly reducing the cooking noise.

[0046] Reference below Figures 1-2 The heating element assembly of the above embodiment of the present invention is described in detail.

[0047] According to an embodiment of the present invention, the inventors have found that the directional heat transfer effect of the heating layer can be improved by increasing the thermal resistance on one side of the heating layer, thereby promoting the heat of the heating layer to be transferred more in the expected direction; further, the mutual embedding connection between the adhesive layer and the heating layer can be used to improve the bonding strength between the heating layer and the inorganic layer (especially the glass layer), and avoid the direct reaction of the metal of the heating layer with the tin surface in the glass layer. In addition, the bonding layer and the heating layer can be embedded in each other to improve the uniformity of the heat transfer from the heating layer to the adhesive layer, and reduce the risk of heat concentration in the adhesive layer. In the present invention, by forming an adhesive layer that is embedded in the heating layer between the heating layer and the second inorganic layer, the heat of the heating layer can be transferred more to the first inorganic layer, and the bonding strength between the heating layer and the second inorganic layer can be further improved by the mutual embedding connection structure of the heating layer and the adhesive layer. At the same time, by embedding the adhesive layer and the heating layer, it can also be improved. The uniformity of heat transfer from the heating layer to the bonding layer reduces the risk of heat concentration in the bonding layer, which can further help improve the bonding force between the bonding layer and the heating layer. In addition, the appropriate bonding layer material can be selected according to the material of the second inorganic layer to improve the bonding strength of the bonding layer and the second inorganic layer. For example, when the second inorganic layer is a glass layer, a bonding layer with a glass phase can be set between the heating layer and the second inorganic layer to avoid direct contact between the heating layer and the glass tin surface. In particular, when the heating layer is heated by a metal material, the bonding layer can also be used to avoid direct contact between the metal elements in the heating layer and the glass tin surface, thereby avoiding the problem that the bonding strength of the heating layer and the second inorganic layer is greatly deteriorated due to the formation of a primary battery reaction at the interface during long-term aging, and the resulting deterioration in the bonding strength, which leads to the deterioration of the cold and heat shock resistance of the second inorganic layer, and the problem of easy deformation or cracking during heating or use.

[0048] According to a specific embodiment of the present invention, a glass phase can be formed in both the heating layer 30 and the bonding layer 40. The glass phase in the heating layer 30 and the glass phase in the bonding layer 40 can be connected to each other, that is, the heating layer 30 and the bonding layer 40 can be embedded and connected to each other through the glass phase, wherein the glass phase in the bonding layer 40 can be formed by a first inorganic oxide (for example, an inorganic glaze that can include silicon oxide, etc.), and the glass phase in the heating layer can be formed by a second inorganic oxide (for example, an inorganic glaze that can include silicon oxide, etc.). This setting can not only further ensure that there is sufficient thermal resistance between the heating layer and the second inorganic layer, promote more heat from the heating layer to be transferred to the first inorganic layer, but also further improve the uniformity of heat transfer from the heating layer to the bonding layer, greatly reducing the risk of heat concentration in the bonding layer; especially when the second inorganic layer is a glass layer, it can further help reduce the interface stress between the bonding layer and the second inorganic layer and the heating layer, and improve the bonding strength between the heating layer and the second inorganic layer, while avoiding direct contact between the heating layer and the glass tin surface of the second inorganic layer. This can further help improve the overall performance of the heating element assembly, such as its anti-shattering ability and service life.

[0049] According to a specific embodiment of the present invention, the melting temperature of the bonding layer 40 may be no higher than the melting temperature of the heating layer 30. This configuration ensures that during the sintering and curing process of the bonding layer, the heating layer will not soften or melt, thereby affecting the performance of the heating layer. Furthermore, a glass phase may be formed in the heating layer 30, and the melting temperature of the glass phase in the heating layer 30 may be greater than the melting temperature of the bonding layer 40. The glass phase in the heating layer may be composed of a second inorganic oxide. This configuration ensures that during the sintering and curing process of the bonding layer, the glass phase in the heating layer will not soften or form a glass phase inorganic oxide, and that the glass phase inorganic oxide will not melt, thereby affecting the performance of the heating layer. Furthermore, the melting temperature of the glass phase in the heating layer 30 can be controlled to be no higher than 800°C. The inventors have discovered that when a glass layer is used as the inorganic layer, if the melting temperature of the glass phase in the heating layer is too high, the second inorganic oxide melts during sintering to form the glass phase, which can easily cause deformation of the glass substrate. By controlling the melting temperature of the glass phase in the heating layer to no higher than 800°C, the heating layer and adhesive layer can be guaranteed to have no effect on the glass substrate during the sintering and curing process, thus preventing deformation of the glass layer.

[0050] According to a specific embodiment of the present invention, the glass phase in the bonding layer 40 can be formed by a first inorganic oxide without adding metal elements, and the glass phase in the heating layer 30 can be formed by a second inorganic oxide, and the second inorganic oxide accounts for a smaller proportion in the heating layer, wherein both the first inorganic oxide and the second inorganic oxide include silicon oxide compounds, and in the unit area cross-section, the content of silicon element in the bonding layer is greater than the content of silicon element in the heating layer. Among them, silicon oxide is a necessary component for forming a glass phase, and the bonding layer mainly plays the role of bonding the heating layer and the inorganic layer, increasing the thermal resistance on the second inorganic layer side, and avoiding the reaction between the metal in the heating layer and the tin surface of the glass inorganic layer when the inorganic layer is a glass layer and the heating layer is heated by a metal material. The glass phase formed by the inorganic oxides in the heating layer and the inorganic oxides in the bonding layer during the sintering and curing process will interpenetrate and bond to improve the bonding effect between the two. However, if the glass phase content in the heating layer is too high, although the bonding strength between the heating layer and the bonding layer can be appropriately improved, it is equivalent to reducing the metal element content in the heating layer, which will affect the heating effect. Controlling the inorganic oxides in the heating layer and the bonding layer to the above conditions can improve the relative bonding strength between the heating layer, the bonding layer and the inorganic layer while ensuring the heating effect.

[0051] It should be noted that the "cross-section per unit area" described in the present invention can be understood as either a cross-section per unit area or a longitudinal section per unit area. For example, the phrase "in a cross-section per unit area, the silicon content in the bonding layer is greater than the silicon content in the heating layer" can be understood as either the silicon content in the cross-section per unit area of ​​the bonding layer is greater than the silicon content in the cross-section per unit area of ​​the heating layer, or the silicon content in the longitudinal section per unit area of ​​the bonding layer is greater than the silicon content in the longitudinal section per unit area of ​​the heating layer. Preferably, both conditions are met.

[0052] According to another specific embodiment of the present invention, the bonding layer 40 can be obtained by using a first inorganic oxide, and the first inorganic oxide can include one or more inorganic glazes, whose main components can include bismuth oxide and silicon oxide, wherein the content of bismuth oxide in the first inorganic oxide can be 30-60wt%, preferably 35-60wt%, for example, 35wt%, 40wt%, 45wt%, 50wt% or 55wt%, and the content of silicon oxide can be 10-40wt%, for example, 40wt%, 35wt%, 30wt%, 25wt%, 20wt%. t% or 15wt%, etc. The inventors found that if the proportion of bismuth oxide in the inorganic oxide is too low, the sintering temperature required for the curing and sintering process of the bonding layer is high, which can easily cause the inorganic layer to soften and deform during the curing and sintering process or crack due to thermal shock; and if the proportion of bismuth oxide in the inorganic oxide is too high, although the sintering temperature and melting point of the bonding layer will be reduced, the difference in expansion coefficient between the bonding layer and the heating layer and the inorganic layer will be too large, and the bonding strength of the bonding layer will be low, which will also cause the inorganic layer to crack under thermal shock, and the high content of bismuth oxide will also cause the water and acid resistance and long-term aging performance of the bonding layer to deteriorate. In the present invention, by controlling the bismuth oxide in the first inorganic oxide to the above content, the sintering temperature of the bonding layer can be controlled to be around 400-800°C, and the excessive expansion coefficient between the bonding layer and the heating layer and the inorganic layer can be avoided, thereby greatly reducing the risk of deformation and cracking of the inorganic layer during sintering and curing or heating, and ensuring its thermal shock resistance and durability. Furthermore, the silicon oxide content in the first inorganic oxide can be 10 to 40 wt%, for example, 40 wt%, 35 wt%, 30 wt%, 25 wt%, 20 wt%, or 15 wt%. By controlling the silicon oxide content to the above, it is more conducive to forming a continuous glass phase network structure in the bonding layer, achieving interpenetration bonding with the heating layer and the second inorganic layer. In addition, the first inorganic oxide can further include at least one selected from aluminum oxide, boron oxide, titanium oxide, zinc oxide, chromium oxide, and lithium oxide, thereby selectively improving the expansion coefficient, strength, and durability of the bonding layer according to actual needs.

[0053] According to another specific embodiment of the present invention, the heating layer 30 includes a certain amount of a second inorganic oxide, which is used to form a glass phase to improve its bonding strength with the bonding layer. The second inorganic oxide may also include one or more inorganic glazes, the main component of which may be silicon oxide, and may not contain bismuth oxide or the bismuth oxide content in the second inorganic oxide is lower than the bismuth oxide content in the first inorganic oxide. The proportion of the second inorganic oxide in the heating layer may be 10-30wt%, for example, 15wt%, 20wt%, 25wt% or 30wt%. By controlling the above conditions in the present invention, it is possible to ensure that the melting point of the glass phase in the heating layer is not lower than the melting point of the glass phase in the bonding layer, and to achieve a glass connection between the heating layer and the bonding layer, ensuring a high bonding strength between the two. At the same time, it is also possible to prevent the excessive content of inorganic oxides in the heating layer from affecting the heating effect of the heating layer. In addition, the second inorganic oxide may further include at least one selected from aluminum oxide, boron oxide, titanium oxide, zinc oxide, chromium oxide, and lithium oxide, thereby selectively improving the performance of the glass phase in the heating layer according to actual needs.

[0054] According to another specific embodiment of the present invention, the thickness of the heating layer 30 in the heating element assembly may be no greater than the thickness of the bonding layer 40. Preferably, the thickness of the heating layer 30 is less than the thickness of the bonding layer 40. This arrangement can further increase the thermal resistance between the heating layer and the second inorganic layer, and reduce the transfer of heat to the second inorganic layer. On the one hand, this can further reduce the internal stress of the second inorganic layer caused by heat concentration, thereby reducing the risk of rupture of the second inorganic layer. For example, when the first inorganic layer is used as the heating surface, the heat on the first inorganic layer can be transferred through the carrier on the first inorganic layer, but the second inorganic layer is prone to heat accumulation. By adopting this arrangement, the risk of rupture of the second inorganic layer can be reduced. Furthermore, the thickness of the heating layer 30 can be 10 to 25 μm, for example, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm or 24 μm, and the thickness of the bonding layer 40 can be 10 to 45 μm, for example, 12 μm, 18 μm, 24 μm, 30 μm, 36 μm, 42 μm or 45 μm, and the inventors found that in the process of preparing the bonding layer, the inorganic oxide is printed on the inorganic layer or the heating layer in the form of a slurry and solidified. The greater the thickness of the bonding layer to be sintered, the greater the actual contact area between the bonding layer, the heating layer and the inorganic layer. Although appropriately increasing the actual contact area can improve the bonding strength, if the bonding layer thickness is too large, the stress will also be large, which will reduce the bonding strength. The inventors have discovered and verified through a large number of experiments that based on the above-mentioned heating layer thickness range, when the bonding layer thickness is in the range of 10 to 45 um, the relative bonding strength between the heating layer and the second inorganic layer is greater, and the relative bonding strength is not less than 30N.

[0055] According to another specific embodiment of the present invention, the orthographic projection of the heating layer 30 on the bonding layer 40 can be located inside the bonding layer 40. Preferably, the area of ​​the orthographic projection of the heating layer 30 on the bonding layer 40 can be smaller than the area of ​​the bonding layer 40. In this way, the bonding layer can fully cover the heating layer and provide complete protection for the heating layer, thereby further ensuring that the heating layer and the second inorganic layer have a higher bonding strength. Furthermore, the contact area between the heating layer 30 and the bonding layer 40 can account for 80 to 96% of the area of ​​the second inorganic layer 20, for example, it can account for 82%, 86%, 90% or 95%. The inventors found that when the relative contact area between the heating layer and the second inorganic layer is small, the second inorganic layer and the bonding layer can play a better role in heat insulation and heat preservation, so that most of the heat is transferred to the first inorganic layer. However, if the relative contact area between the two is too small, it is easy to cause more air to exist in the sandwich structure between the first inorganic layer and the second inorganic layer, forming stress during the welding process and use, affecting the service life. By controlling the relative contact area between the heating layer and the second inorganic layer to be within the above range, the second inorganic layer and the bonding layer can play a certain role in heat insulation and heat preservation, improve the utilization rate of heat, and it is also beneficial to reduce the stress during the welding process and use, and improve the reliability and service life of the heating element assembly.

[0056] According to another specific embodiment of the present invention, a glass phase can be formed in both the heating layer 30 and the bonding layer 40. In at least a portion of the region of the heating element assembly, the first inorganic layer 10 and the second inorganic layer 20 can be connected via the glass phase in the heating layer 30 and the glass phase in the bonding layer 40, thereby further improving the overall strength and bonding effect of the heating element assembly. Preferably, the first inorganic layer 10 and the second inorganic layer 20 can also be glass layers, and more preferably, the first inorganic layer 10, the heating layer 30, the bonding layer 40 and the second inorganic layer 20 can all be embedded and connected to each other via the glass phase, thereby making the bonding strength between the layers higher, and making the heating element assembly have an overall strength and bonding effect close to that of an integral molding, thereby further improving the reliability and service life of the heating element assembly.

[0057] According to another specific embodiment of the present invention, referring to Figure 6 As shown, the connection interface between the bonding layer 40 and the second inorganic layer 20 can be a relatively flat surface. The inventors have found that when the bonding layer and the second inorganic layer are connected through a relatively flat surface, it can further help to increase the thermal resistance of heat transfer to the second inorganic layer and improve the efficiency of heat transfer to the first inorganic layer, thereby further helping to improve the utilization rate of heat.

[0058] According to another specific embodiment of the present invention, the first inorganic layer 10 and the second inorganic layer 20 can be arranged relative to each other, and the first inorganic layer 10 only needs to be in contact with the food or water to be heated. For example, the first inorganic layer can be arranged above the second inorganic layer, and the second inorganic layer located at the bottom of the component is in contact with a heat source such as an induction cooker or an electric heating base, so that the heat generated by the heating layer is transferred from bottom to top. This arrangement is more conducive to obtaining heatable dishes with existing appearance and shape.

[0059] According to another specific embodiment of the present invention, the thickness of the first inorganic layer 10 may be no greater than the thickness of the second inorganic layer 20, and preferably the thickness of the first inorganic layer 10 is less than the thickness of the second inorganic layer 20, wherein the first inorganic layer can be in contact with the food or water to be heated. The use of a relatively thin first inorganic layer can improve the energy utilization rate during the heating process, so that most of the heat is transferred to the first inorganic layer, and then to the food or water; and the use of a relatively thick second inorganic layer can make the second inorganic layer have a better temperature limiting and heat insulating effect, so that the overall temperature of the vessel (such as a glass pot body) with the heating element assembly can be better reduced, so that the stress generated by the vessel during the heating process is smaller, thereby achieving the purpose of improving the durability of the vessel. Furthermore, the thickness difference between the first and second inorganic layers can be 0.05 to 3 mm, specifically 0.5 mm, 1 mm, 2 mm, or 2.5 mm. The inventors have discovered that a larger thickness difference between the first and second inorganic layers increases the efficiency of upward heat transfer and energy utilization. A smaller thickness of the first inorganic layer reduces strength. The minimum thickness of the first inorganic layer is preferably 0.5 to 2 mm, for example, 0.5 mm, 1 mm, 1.2 mm, 1.5 mm, or 2 mm. By controlling the first and second inorganic layers to meet these conditions, the directional heat transfer advantage of the heating element assembly can be further maintained, improving heat utilization while also ensuring sufficient strength.

[0060] According to another specific embodiment of the present invention, the first inorganic layer 10 and the second inorganic layer 20 can be independently a glass layer, a ceramic layer or a microcrystalline glass plate, wherein the type of glass layer is not particularly limited, and those skilled in the art can make a choice according to actual needs, for example, high borosilicate glass, high aluminum glass or alkali-free glass can be used. Relative to existing glassware, using the heating element assembly of the above embodiment of the present invention for glassware can not only improve energy utilization and the safety of glassware, but also design the specific structure of the glassware according to the actual arrangement of the heating plate or heating tube, so as to increase the effective contact area between the glassware and the heating plate or heating tube. Preferably, the first inorganic layer 10 and the second inorganic layer 20 can be independently a high borosilicate glass layer, which has better heat resistance and low expansion coefficient, and has excellent properties such as high strength, high hardness, high light transmittance and high chemical stability. Using it in a heating element assembly or glassware is more conducive to improving the safety and durability of heatable glassware.

[0061] According to another specific embodiment of the present invention, the heating layer 30 and the first inorganic layer 10 can be directly connected or indirectly connected through a transition layer 50 (see Figure 2 As shown), for example, the transition layer 50 can be interpenetrated and bonded with the first inorganic layer 10 and the heating layer 30. The inventors found that by setting the transition layer, a certain thermal resistance can be generated between the heating layer and the first inorganic layer, thereby improving the thermal resistance between the heating layer and the first inorganic layer, reducing the internal stress of the first inorganic layer caused by heat concentration, and thus reducing the risk of rupture of the inorganic layer; further, relative to the relatively flat connection interface, by independently forming an interpenetration bond between the transition layer and the heating layer and the first inorganic layer, that is, forming a mutually embedded connection structure, on the one hand, the bonding strength between the heating layer and the first inorganic layer can be improved, and on the other hand, it can further promote the transfer of heat to the first inorganic layer, and improve the transfer of heat from the heating layer to the transition layer and the heat transfer of the transition layer The uniformity of heat transfer to the first inorganic layer can be improved, thereby further improving the heat utilization rate and reducing the risk of heat concentration in the transition layer and the first inorganic layer; furthermore, although forming a certain thermal resistance between the heating layer and the first inorganic layer can reduce the risk of heat concentration in the first inorganic layer, if the thermal resistance is too large, it will also significantly affect the heat transfer efficiency. The inventors found that compared with the flat connection interface, the thermal resistance generated by the interpenetrating and bonded interface structure is smaller. In the present invention, by forming an interpenetrating and bonded connection interface between the transition layer and the first inorganic layer rather than a relatively flat connection interface, not only can the bonding strength between the transition layer and the first bonding layer be guaranteed, but also the excessive thermal resistance between the transition layer and the first inorganic layer can be avoided, thereby affecting the heat transfer efficiency.

[0062] According to another specific embodiment of the present invention, the transition layer 50 may include an inorganic oxide, which may also be provided by one or more inorganic glazes. Preferably, the inorganic oxides in both the heating layer and the transition layer include silicon oxide compounds. In a unit area cross-section, the silicon content in the heating layer is less than that in the transition layer. Silicon oxide compounds are necessary raw materials for forming a glass phase. The inventors have found that by forming more silicon oxide compounds in the transition layer, on the one hand, the thermal resistance between the heating layer and the first inorganic layer can be increased, and the internal stress of the first inorganic layer caused by heat concentration can be reduced, thereby reducing the risk of cracking of the inorganic layer. On the other hand, the inorganic oxides such as silicon oxide compounds in the transition layer and the heating layer (such as glazes such as silicon oxide) can form a glass phase after sintering and interpenetrate and bond, thereby significantly improving the bonding strength between the transition layer and the heating layer, and further improving the bonding strength between the heating layer and the first inorganic layer. In particular, when the first inorganic layer is a glass layer, the bonding strength between the transition layer, the first inorganic layer, and the heating layer can be further improved. Thus, the safety and service life of the product can be further improved. Furthermore, the heating layer 30, the transition layer 50 and the bonding layer 40 may all include silicon oxides. In the unit area cross-section, the silicon content in the heating layer 30 may be less than the silicon content in the transition layer 50, and the silicon content in the bonding layer 40 is greater than the silicon content in the transition layer 50. This can ensure the bonding strength between the heating layer and the transition layer and the bonding layer, as well as the first inorganic layer and the second inorganic layer, and can further ensure a higher thermal resistance between the heating layer and the second inorganic layer, ensuring that more heat can be transferred toward the first inorganic layer. This can further improve the heat utilization and heat transfer efficiency on the basis of ensuring the overall bonding strength.

[0063] According to another specific embodiment of the present invention, a glass phase is formed in the transition layer 50. The melting temperature of the glass phase in the bonding layer 40 can be no greater than the melting temperature of the glass phase in the transition layer 50, and can preferably be lower than the melting temperature of the glass phase in the transition layer 50. This ensures that the glass phase in the pre-formed transition layer will not melt during the bonding layer sintering and curing process, thereby affecting the performance of the heating layer. Furthermore, the melting temperature of the glass phase in the transition layer 50 can be controlled to be no higher than 800°C. The inventors have discovered that when a glass layer is used as the inorganic layer, if the melting temperature of the glass phase in the transition layer is too high, the glass substrate can be easily deformed during sintering to form the transition layer. By controlling the melting temperature of the glass phase in the transition layer to no more than 800°C, the transition layer and the bonding layer can be free of impact on the glass substrate during the sintering and curing process, thus avoiding deformation of the glass layer. In addition, the main components of the inorganic oxides in the transition layer, the heating layer, and the bonding layer can be the same or different. When the main components are the same, the melting point of the glass phase can be adjusted by adjusting the ratio of the main inorganic oxide components in each layer.

[0064] According to another specific embodiment of the present invention, the transition layer 50 may contain no metal elements or a small amount of metal elements. In a unit cross-sectional area, the metal element content in the heating layer 30 should be greater than the metal element content in the transition layer 50. The inventors have discovered that the metal elements in the heating layer are mainly used to generate eddy currents and thus generate heat during the heating process, thereby ensuring the heating effect and heat transfer efficiency of the heating layer. By also forming metal elements in the transition layer 50 and making the metal element content (also understood as the dispersion density) in the transition layer less than the metal element content in the heating layer, on the one hand, more glass phases can be formed in the transition layer, thereby increasing the thermal resistance between the heating layer and the first inorganic layer, reducing the internal stress caused by heat concentration in the inorganic layer, and reducing the risk of cracking of the inorganic layer. On the other hand, a certain amount of heat conduction can be generated in the transition layer, reducing the internal stress in the transition layer and the internal stress caused by heat accumulation at the interface between the transition layer and the heating layer, and improving the bonding strength between the transition layer and the first inorganic layer, as well as the bonding strength between the heating layer and the transition layer. In addition, the uniformity of heat transfer can be improved, ensuring that the food or water to be heated is heated evenly during the heating process.

[0065] According to another specific embodiment of the present invention, the metal elements in the heating layer 30 may include magnetically sensitive metal elements, such as weakly magnetic materials with a relative magnetic permeability of less than 1. Specifically, the weakly magnetic material may be a diamagnetic material (a diamagnetic material refers to a weakly magnetic material with a negative and very small relative magnetic susceptibility). For example, the weakly magnetic material may be one or more of silver, aluminum, and copper. This allows electromagnetic heating of the heating element assembly, so that the heating layer has a more suitable induction resistance and achieves a higher heating power. Specifically, in an alternating magnetic field environment, magnetically sensitive metals such as silver are used to generate eddy currents and thus generate heat. Most of the generated heat is transferred to food and water through the first inorganic layer, and the second inorganic layer can provide thermal insulation. Furthermore, the types of metal elements used in the transition layer 50 and the heating layer 30 can be the same, and the types of glass phases in the transition layer 50 and the heating layer 30 can also be the same. This not only avoids the increase in interfacial stress between the transition layer and the heating layer due to the large difference in thermal conductivity of different metals, but also further improves the bonding strength between the transition layer and the heating layer through the sintering process, thereby further improving the heat transfer effect, crack resistance, safety, and service life of the product.

[0066] According to another specific embodiment of the present invention, the thickness of the transition layer 50 can be no greater than the thickness of the heating layer 30. This not only ensures that the internal stress of the transition layer is small during the heating process, but also, when the inorganic layer is a glass layer, the transition layer is a silver glaze composite layer, and the heating layer is a silver film, since the properties of the transition layer are between glass and metallic silver, controlling the thickness of the transition layer to be less than the thickness of the heating layer can further improve the bonding strength between the silver film and the glass. Furthermore, the thickness of the transition layer 50 can be 0.1 to 5 μm, for example, 0.1 μm, 1 μm, 2 μm, 3 μm, 4 μm, or 5 μm. The inventors have found that as the thickness of the transition layer increases, the bonding strength between the heating layer and the inorganic layer increases and then decreases. The inventors have found and verified through a large number of experiments that by controlling the thickness of the transition layer to 0.1 to 5 μm, the relative bonding strength between the heating layer and the inorganic layer can be made no less than 30N.

[0067] According to another specific embodiment of the present invention, the orthographic projection of the heating layer 30 on the transition layer 50 can be located inside the transition layer 50. Preferably, the area of ​​the orthographic projection of the heating layer 30 on the transition layer 50 can be smaller than the area of ​​the transition layer 50, thereby allowing the transition layer to fully cover the heating layer, thereby providing complete protection for the heating layer.

[0068] According to another specific embodiment of the present invention, the heating layer 30 may be a silver layer. It should be noted that the silver layer also contains a small amount of inorganic oxides or glass phase components. The inventors have discovered that using a silver film as the heating layer can electromagnetically heat the heating element assembly. The silver film generates eddy currents in an alternating magnetic field environment, which in turn generates heat, resulting in high heating efficiency. For example, when the heating element assembly is used in a glass electric kettle, most of the heat generated by the silver film is transferred to the food and water through the upper glass layer for cooking. The lower glass plate provides thermal insulation and greater strength, resulting in a high heating efficiency of the kettle, capable of heating at 1000-2000W.

[0069] According to another specific embodiment of the present invention, the heating layer includes no less than 70wt% of metal elements, for example, it may include 75wt%, 80wt%, 85wt% or 90wt% of metal elements, thereby further ensuring the heating effect.

[0070] In summary, the heating element assembly of the above embodiment of the present invention forms an adhesive layer embedded and connected with the heating layer between the heating layer and the second inorganic layer. On the one hand, it can increase the thermal resistance between the heating layer and the second inorganic layer, and promote more heat from the heating layer to be transferred to the first inorganic layer; on the other hand, it can further improve the bonding strength between the heating layer and the second inorganic layer through the structure of mutual embedding connection between the heating layer and the adhesive layer, and at the same time improve the uniformity of heat transfer from the heating layer to the adhesive layer, and reduce the risk of heat concentration in the adhesive layer, which can further help to improve the bonding force between the adhesive layer and the heating layer; on the other hand, it can also be selected according to the material of the second inorganic layer. Select a suitable bonding layer material to improve the bonding strength between the bonding layer and the second inorganic layer. For example, when the second inorganic layer is a glass layer, a bonding layer with a glass phase can be provided between the heating layer and the second inorganic layer to avoid direct contact between the heating layer and the glass tin surface. In particular, when the heating layer is heated by a metal material, it is also preferred that the bonding layer does not contain metal elements. This can avoid the problem that the bonding strength of the heating layer and the second inorganic layer may be greatly deteriorated due to the formation of a primary battery reaction at the interface during long-term aging, and the resulting deterioration in the bonding strength, which leads to the deterioration of the cold and heat shock resistance of the second inorganic layer, and the problem of easy deformation or cracking during heating or use. Therefore, compared with the prior art, the heating element assembly not only has an advantageous heat conduction direction during use, but also has better anti-fragmentation ability and higher safety. In addition, the bonding force between the heating layer and the second inorganic layer is strong and durable, and can be widely used in products such as heated pots, inner pots of cooking utensils or electric kettles.

[0071] According to the second aspect of the present invention, the present invention provides a method for preparing the above-mentioned heating element assembly. Figure 3 As shown, the method includes:

[0072] S100: forming a heating layer on the first inorganic layer using a heating layer slurry, and forming a bonding layer on the heating layer using a bonding layer slurry

[0073] According to an embodiment of the present invention, the heating layer slurry includes a metal element, a second inorganic oxide, and an organic solvent. The metal element may include silver. The second inorganic oxide may be primarily composed of silicon oxide, and the remaining components may be one or more selected from boron oxide, titanium oxide, zinc oxide, chromium oxide, lithium oxide, aluminum oxide, and bismuth oxide. The organic solvent may be an alcohol. The bonding layer slurry includes a first inorganic oxide and an organic solvent. The primary components of the organic solvent and inorganic oxide used in the bonding layer slurry may be the same as those used in the heating layer slurry. However, it should be noted that the bismuth oxide content of the first inorganic oxide may preferably be 30-60 wt%, and the silicon oxide content may be 10-40 wt%. Furthermore, the solid content of the bonding layer slurry and the heating layer slurry may be controlled to be 60-90 wt%, respectively. This allows for further reducing the amount of solvent used while ensuring uniform coating or printing, thereby preventing excessive solvent from affecting drying efficiency or sintering effects.

[0074] According to one embodiment of the present invention, the heating layer slurry can be printed on the first inorganic layer first, and then the bonding layer slurry can be printed after surface drying or baking treatment, and then surface drying or baking treatment can be performed again, and then sintering treatment can be performed together, thereby further shortening the process flow; the heating layer slurry can also be printed on the first inorganic layer first, then dried and sintered once, and after sintering is completed, the bonding layer slurry can be printed on the heating layer, and after drying or baking, sintering treatment can be performed again, thereby further ensuring the bonding strength between the heating layer and the first inorganic layer and the bonding layer. It should be noted that the temperature for drying or baking treatment is not particularly limited, and those skilled in the art can select it according to actual needs. For example, the temperature for drying or baking treatment can be 120-160°C; in addition, the temperature for sintering after printing the slurry can be 550-650°C, thereby ensuring that the inorganic oxides in the heating layer and the bonding layer can form a glass phase, thereby ensuring its bonding strength with the inorganic layer such as the glass layer.

[0075] According to another embodiment of the present invention, the heating layer and the first inorganic layer can be further connected by a transition layer, wherein the transition layer can be formed by regulating the heating layer slurry and the sintering process so that the effective ingredients in the heating layer are layered. Specifically, the heating layer slurry formed on the first inorganic layer can be dried and sintered, and the process conditions during the sintering process can be strictly controlled so that the metal elements and inorganic oxides in the heating layer slurry move in a direction at the junction with the first inorganic layer, most of the metal elements tend to move away from the first inorganic layer, and most of the inorganic oxides tend to move toward the first inorganic layer, thereby forming an interlocking and bonded transition layer and the heating layer; but the inventors found that although this method is simple, it is difficult to accurately control the thickness of the transition layer and the proportion of the glass phase and metal elements in the transition layer. To solve this problem, the transition layer can also be formed by printing a transition layer slurry. Specifically, the transition layer slurry can be printed on the first inorganic layer in advance and dried or sintered, and then the heating layer is formed on the transition layer obtained by drying or sintering. It should be noted that the transition layer, the heating layer and the bonding layer can be dried and then co-sintered, or they can be sintered separately in layers.

[0076] S200: Sintering the first inorganic layer with the heating layer and the bonding layer and the second inorganic layer so that the first inorganic layer and the second inorganic layer are bonded to obtain a heating element assembly

[0077] According to a specific embodiment of the present invention, the first inorganic layer formed with a heating layer, a bonding layer and optionally a transition layer can be sintered with the second inorganic layer to achieve bonding between the inorganic layers, wherein the sintering temperature can be 550-650°C, thereby enabling the inorganic oxides in the heating layer and the bonding layer to form a glass phase and interpenetrate and bond, thereby improving the bonding strength between the two.

[0078] It should be noted that the characteristics and effects described for the above-mentioned heating element assembly are also applicable to the method for preparing the heating element assembly, and will not be described in detail here.

[0079] In summary, the method for preparing a heating element assembly according to the above embodiment of the present invention has at least the following advantages: by forming an adhesive layer embedded and connected with the heating layer between the heating layer and the second inorganic layer, on the one hand, the thermal resistance between the heating layer and the second inorganic layer can be increased, and the heat of the heating layer can be promoted to be transferred more to the first inorganic layer; on the other hand, the mutual embedding connection of the heating layer and the adhesive layer can be achieved by sintering, which not only can further improve the bonding strength between the heating layer and the second inorganic layer, but also can improve the uniformity of the heat transfer from the heating layer to the adhesive layer, and reduce the risk of heat concentration in the adhesive layer, which can further help to improve the bonding force between the adhesive layer and the heating layer; on the other hand, it can also be based on According to the material of the second inorganic layer, a suitable bonding layer material is selected to improve the bonding strength between the bonding layer and the second inorganic layer. For example, when the second inorganic layer is a glass layer, a bonding layer with a glass phase can be provided between the heating layer and the second inorganic layer to avoid direct contact between the heating layer and the glass tin surface. In particular, when the heating layer is heated by a metal material, it is also preferred that the bonding layer does not contain metal elements. This can avoid the problem that the bonding strength between the heating layer and the second inorganic layer is greatly deteriorated due to the formation of a galvanic cell reaction at the interface during long-term aging, and the resulting deterioration in the bonding strength, which leads to the deterioration of the cold and heat shock resistance of the second inorganic layer, and the problem of easy deformation or cracking during heating or use. Compared with the prior art, the heating element assembly prepared by this method not only has an advantageous heat conduction direction during use, but also has better anti-fragmentation ability and higher safety. In addition, the bonding force between the heating layer and the second inorganic layer is strong and durable, and can be widely used in products such as heated pots, inner pots of cooking utensils or electric kettles.

[0080] According to a third aspect of the present invention, a heatable dish is provided. According to an embodiment of the present invention, the heatable dish comprises the aforementioned heating element assembly or a heating element assembly produced using the aforementioned method for producing a heating element assembly. Compared to existing technologies, the heatable dish exhibits an advantageous heat conduction direction during heating, is less susceptible to breakage, and exhibits high safety, good thermal stability, and a longer service life.

[0081] According to a specific embodiment of the present invention, the heating element assembly can be arranged at the bottom of the heatable dish. This arrangement is not only conducive to the effective connection between the heating element assembly and other parts of the heatable dish, and increases the contact area between the heat source and the heating element assembly, but also can better enable the heatable dish to heat food or water. Figure 4It is understood that the heatable dish may include a side wall 60 and a bottom wall that are sealed and connected, and at least a portion of the bottom wall may be a heating element component. This arrangement allows the inorganic layer of the heating element component to directly contact food or water for heat transfer, thereby further improving the heat transfer efficiency and simplifying the structure of the heatable dish. Furthermore, the heating element component and the side wall may be sealed and connected by fusion welding. Specifically, the heating element component may be preheated first, and then the edge and side wall of the heating element component may be welded using a heat source such as a flame or a plasma flame (the welding area may refer to Figure 4 70), after welding is completed, the vessel is annealed to relieve stress. The preheating temperature can be 300-600°C, for example, 350°C, 400°C, 450°C, 500°C, 550°C or 600°C, and the annealing temperature can be 500-700°C, for example, 500°C, 540°C, 580°C, 620°C, 660°C or 700°C, which not only ensures the sealed connection between the heating element assembly and the side wall of the vessel, but also helps to eliminate the residual permanent stress in the heatable vessel.

[0082] According to another specific embodiment of the present invention, the side wall and the bottom wall define a cavity for the heatable dish, and the average thickness of the heating element assembly can be smaller than the average thickness of the side wall. During the heating process, most of the heat generated by the heating layer will be transferred to the cavity of the heatable dish, and the heat transfer of the side wall is relatively small. The inorganic layer corresponding to the heating layer is more likely to produce uneven heat distribution. In the present invention, by making the thickness of the heating element assembly thinner, the heat transfer distance can be shortened, the uniformity of heat conduction at the bottom and the heat conduction rate at the bottom are improved, the heat of the bottom wall can be extracted faster, and the risk of heat concentration on the bottom wall is reduced; in addition, the thickness of the side wall is thicker, on the one hand, it can improve the overall strength of the heatable dish, and on the other hand, most of the heat transferred to the side wall will contact with the air and cause excessive heat loss. Making the side wall thicker is also beneficial to reducing the transfer rate of heat from the bottom to the side wall, thereby reducing the heat loss of the side wall and concentrating more heat at the bottom of the container, thereby further improving the heat utilization rate.

[0083] According to another specific embodiment of the present invention, the material of the heatable utensils in the present invention can be glass, microcrystalline glass or ceramics, for example, preferably high borosilicate glass, etc., and the glass-made heatable utensils with the above-mentioned heating element component structure of the present invention are used as cooking pots or kettles. It can effectively improve the problems of existing glassware such as small contact area with the heat source, low heat transfer efficiency, and easy breakage, thereby ensuring the durability of the utensils and safety during use.

[0084] According to another specific embodiment of the present invention, the specific type of heatable utensils in the present invention is not particularly limited, and those skilled in the art can select according to actual needs. For example, the heatable utensils can be pots, inner pots or pot bodies of cooking utensils, etc., for example, they can be directly heated glass pots, inner pots or glass pot bodies of electric pots, etc.

[0085] It should be noted that the features and effects described for the above-mentioned heating element assembly and the above-mentioned method for preparing the heating element assembly are applicable to the heatable dish and will not be described in detail here.

[0086] According to a fourth aspect of the present invention, the present invention provides an electrical appliance. According to an embodiment of the present invention, the electrical appliance includes the above-mentioned heatable dishes. Compared with the prior art, the electrical appliance has the advantages of less safety hazards and longer service life, which is more conducive to improving customer satisfaction. It should be noted that the specific type of the electrical appliance is not particularly limited, and those skilled in the art can choose according to actual needs. For example, the electrical appliance can be a cooker, an electric rice cooker, a pressure cooker, an electric kettle, an electric stew pot, an induction cooker pot set or a microcrystalline pot pot set, etc., wherein the pot can be a separate pot body or include a matching cover. In addition, it should be noted that the features and effects described for the above-mentioned heatable dishes are also applicable to the electrical appliance, and will not be described in detail here.

[0087] The examples described below are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention. Where specific techniques or conditions are not specified in the examples, the methods or conditions described in the literature in this field or in the product specifications were used. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0088] Example 1

[0089] (1) Printing a heating layer slurry on a first glass substrate (made of high borosilicate, with a thickness of 0.7 mm) using a 100-300 mesh screen, drying at 150°C after printing, and sintering at 550-650°C to form a heating layer with a thickness of 20 μm. The solid content of the heating layer slurry is 80 wt%, and the composition of the heating layer slurry includes metallic silver, inorganic glaze, and alcohol organic solvent. The mass ratio of metallic silver to inorganic oxide in the formed heating layer is 4:1. The inorganic oxide includes 7 wt% silicon oxide, 2 wt% aluminum oxide, and 9 wt% bismuth oxide. The remaining 2% is potassium oxide, titanium oxide, boron oxide, lithium oxide, zinc oxide, calcium oxide, magnesium oxide, iron oxide, and unavoidable impurities.

[0090] (2) Printing a bonding layer slurry on the heating layer using a 100-300 mesh screen, drying the slurry at 150°C after printing, and sintering the slurry at 550-650°C to form a bonding layer with a thickness of 25 μm. The bonding layer slurry comprises an inorganic glaze and an alcohol organic solvent. The inorganic oxides in the formed bonding layer include 20 wt% silicon oxide, 10 wt% aluminum oxide, and 45 wt% bismuth oxide. The remaining 25% is potassium oxide, titanium oxide, boron oxide, lithium oxide, zinc oxide, calcium oxide, magnesium oxide, iron oxide, and unavoidable impurities.

[0091] (3) The first glass substrate obtained in step (2) and the second glass substrate (made of high borosilicate, with a thickness of 2 mm) are sintered at a sintering temperature of 550-650° C. to soften the glaze in the bonding layer and the heating layer. The first glass substrate and the second glass substrate are then wetted and solidified after cooling. The two glass plates are bonded together, and the bonding layer is connected to the second glass substrate.

[0092] Example 2

[0093] The difference from Example 1 is that in step (2), the inorganic oxide includes 30wt% silicon oxide, 5wt% aluminum oxide and 50wt% bismuth oxide, and the remaining 15% is potassium oxide, titanium oxide, boron oxide, lithium oxide, zinc oxide, calcium oxide, magnesium oxide, iron oxide, etc.

[0094] Example 3

[0095] The difference from Example 1 is that in step (2), the inorganic oxide includes 20 wt% of silicon oxide, 10 wt% of aluminum oxide and 60 wt% of bismuth oxide, and the remaining 10% is potassium oxide, titanium oxide, boron oxide, lithium oxide, zinc oxide, calcium oxide, magnesium oxide, iron oxide, and inevitable impurities.

[0096] Comparative Example 1

[0097] The difference from Example 1 is that in step (2), the inorganic oxide includes 60wt% of silicon oxide, 10wt% of aluminum oxide and 15wt% of bismuth oxide, and the remaining 15% is potassium oxide, titanium oxide, boron oxide, lithium oxide, zinc oxide, calcium oxide, magnesium oxide, iron oxide, and inevitable impurities.

[0098] Comparative Example 2

[0099] The difference from Example 1 is that in step (2), the inorganic oxide includes 15wt% silicon oxide, 5wt% aluminum oxide and 70wt% bismuth oxide, and the remaining 10% is potassium oxide, titanium oxide, boron oxide, lithium oxide, zinc oxide, calcium oxide, magnesium oxide, iron oxide, and inevitable impurities.

[0100] The sintering temperature required for different bonding layer glaze compositions in Examples 1 to 3 and Comparative Examples 1 to 2, the expansion coefficient between the bonding layer and the heating layer / glass substrate, and the changes in the glass substrate during the curing and sintering process were tested. The detection method was a hot and cold shock test: the sample was placed in a muffle furnace and heated to 160°C, kept warm for 30 minutes, and then immersed in ice water (0°C). This was considered one cycle, and 5 consecutive cycles were repeated to observe whether there was any cracking.

[0101] Table 1 Test results of the effect of bismuth oxide content on glass substrates in Examples 1 to 3 and Comparative Examples 1 to 2

[0102]

[0103] As can be seen from Table 1, if the bismuth oxide content in the inorganic glaze forming the bonding layer is too high or too low, it is easy to cause the glass substrate to deform or crack under thermal shock. Controlling the bismuth oxide content in the inorganic glaze to 30-60 wt% can improve the durability of the glass substrate.

[0104] Example 4

[0105] The difference from Example 1 is that the thickness of the adhesive layer is 10 μm.

[0106] Example 5

[0107] The difference from Example 1 is that the thickness of the adhesive layer is 15 μm.

[0108] Example 6

[0109] The difference from Example 1 is that the thickness of the adhesive layer is 25 μm.

[0110] Example 7

[0111] The difference from Example 1 is that the thickness of the adhesive layer is 35 μm.

[0112] Example 8

[0113] The difference from Example 1 is that the thickness of the adhesive layer is 45 μm.

[0114] Comparative Example 3

[0115] The difference from Example 1 is that the thickness of the adhesive layer is 5 μm.

[0116] Comparative Example 4

[0117] The difference from Example 1 is that the thickness of the adhesive layer is 55 μm.

[0118] The actual contact area and bonding strength of the bonding layer of different bonding layer thicknesses in Examples 4 to 8 and Comparative Examples 3 to 4 were tested, wherein the testing method refers to the adhesion test of precious metal pastes used in microelectronics technology in GB / T17473.4, that is, Figure 5 As shown, copper wire was soldered to a precious metal paste film. The copper wire was bent 90° perpendicular to the substrate surface and placed on a tensile testing machine. The wire was uniformly pulled off the substrate at a constant speed. The average value of the wire being pulled off was used to represent the adhesion of the paste. The test results are shown in Table 2.

[0119] Table 2 Comparison of actual contact area and bonding strength of bonding layer at different bonding layer thicknesses

[0120]

[0121] From Table 2, it can be seen that too large or too small a thickness of the adhesive layer will affect the relative bonding strength between the heating layer and the glass substrate. Controlling the thickness of the adhesive layer to 10 to 45 μm can make the relative bonding strength between the heating layer and the glass substrate reach above 30N.

[0122] Example 9

[0123] The difference from Example 1 is:

[0124] 1) Printing a transition layer slurry on a first glass substrate (made of borosilicate, 0.7 mm thick) using a 100-300 mesh screen. After printing, the slurry is dried at 150°C and sintered at 550-650°C to form a transition layer with a thickness of 0.1 μm. The solid content of the transition layer slurry is 75 wt%. The transition layer slurry comprises metallic silver, an inorganic glaze, and an alcohol-based organic solvent. The mass ratio of metallic silver to inorganic glaze in the formed transition layer is 1:4. The inorganic oxides comprise 10 wt% silicon oxide, 10 wt% aluminum oxide, and 55 wt% bismuth oxide. The remaining 5% is potassium oxide, titanium oxide, boron oxide, lithium oxide, zinc oxide, calcium oxide, magnesium oxide, iron oxide, and unavoidable impurities.

[0125] 2) Printing a heating layer slurry on the transition layer using a 100-300 mesh screen, drying at 150°C after printing, and sintering at 550-650°C to form a heating layer with a thickness of 25 μm. The solid content of the heating layer slurry is 90 wt%, and the composition of the heating layer slurry includes metallic silver, inorganic glaze, and alcohol organic solvent. The mass ratio of metallic silver to inorganic oxide in the formed heating layer is 4:1. The inorganic oxide includes 8 wt% silicon oxide, 2 wt% aluminum oxide, and 9 wt% bismuth oxide. The remaining 1% is potassium oxide, titanium oxide, boron oxide, lithium oxide, zinc oxide, calcium oxide, magnesium oxide, iron oxide, and unavoidable impurities.

[0126] Example 10

[0127] The difference from Example 9 is that the thickness of the transition layer is 1 μm.

[0128] Example 11

[0129] The difference from Example 9 is that the thickness of the transition layer is 3 μm.

[0130] Example 12

[0131] The difference from Example 9 is that the thickness of the transition layer is 5 μm.

[0132] Comparative Example 5

[0133] The difference from Example 9 is that the thickness of the transition layer is 0.05 μm.

[0134] Comparative Example 6

[0135] The difference from Example 9 is that the thickness of the transition layer is 7 μm.

[0136] Comparative Example 7

[0137] The difference from Example 9 is that the thickness of the transition layer is 9 μm.

[0138] The bonding strength between the heating layer and the glass substrate at different transition layer thicknesses in Examples 9 to 12 and Comparative Examples 5 to 7 was tested, wherein the testing method was an adhesion test referring to the precious metal slurry testing method for microelectronics technology in GB / T 17473.4. The test results are shown in Table 3.

[0139] Table 3 Bonding strength between the heating layer and the glass substrate at different transition layer thicknesses

[0140]

[0141]

[0142] As can be seen from Table 3, too large or too small a thickness of the transition layer will affect the relative bonding strength between the heating layer and the glass substrate. Controlling the thickness of the transition layer to 0.1 to 5 μm can ensure that the relative bonding strength between the heating layer and the glass substrate is not less than 30N.

[0143] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0144] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A heating element assembly, which is used in household appliances, characterized in that: include: a first inorganic layer and a second inorganic layer, wherein a heating layer and an adhesive layer are sandwiched between the first inorganic layer and the second inorganic layer, wherein one side of the heating layer is connected to the first inorganic layer and the other side is connected to the second inorganic layer through the adhesive layer, and the heating layer and the adhesive layer are embedded and connected to each other; A glass phase is formed in both the heating layer and the bonding layer, and the glass phase in the heating layer and the glass phase in the bonding layer are connected to each other; The glass phase in the bonding layer is formed by a first inorganic oxide, and the glass phase in the heating layer is formed by a second inorganic oxide. Both the first inorganic oxide and the second inorganic oxide include silicon oxide compounds. In a unit area cross-section, the silicon content in the bonding layer is greater than the silicon content in the heating layer.

2. The heating element assembly according to claim 1, characterized in that The melting temperature of the bonding layer is not higher than the melting temperature of the heating layer.

3. The heating element assembly according to claim 2, characterized in that A glass phase is formed in the heating layer, the melting temperature of the glass phase in the heating layer is greater than the melting temperature of the bonding layer, and the melting temperature of the glass phase in the heating layer is not higher than 800°C.

4. The heating element assembly according to claim 1, wherein: At least one of the following conditions is met: The first inorganic oxide comprises 30-60 wt% of bismuth oxide and 10-40 wt% of silicon oxide; The second inorganic oxide includes silicon oxide, and the proportion of the second inorganic oxide in the heating layer is 10-30 wt %; The first inorganic oxide and the second inorganic oxide each independently include at least one selected from the group consisting of aluminum oxide, boron oxide, titanium oxide, zinc oxide, chromium oxide, and lithium oxide.

5. The heating element assembly according to claim 1 or 4, characterized in that: At least one of the following conditions is met: The thickness of the heating layer is not greater than the thickness of the bonding layer; The orthographic projection of the heating layer on the bonding layer is located inside the bonding layer; A glass phase is formed in both the heating layer and the bonding layer, and in at least a portion of the heating element assembly, the first inorganic layer and the second inorganic layer are connected via the glass phase in the heating layer and the glass phase in the bonding layer; The connection interface between the adhesive layer and the second inorganic layer is a relatively flat surface.

6. The heating element assembly according to claim 5, characterized in that: The thickness of the heating layer is 10-25 μm, and the thickness of the bonding layer is 10-45 μm.

7. The heating element assembly according to claim 1 or 6, characterized in that: At least one of the following conditions is met: The first inorganic layer and the second inorganic layer are arranged opposite to each other; The thickness of the first inorganic layer is not greater than the thickness of the second inorganic layer; The first inorganic layer and the second inorganic layer are independently a glass layer, a ceramic layer or a glass-ceramic plate; The heating layer and the first inorganic layer are connected via a transition layer.

8. The heating element assembly according to claim 7, characterized in that: At least one of the following conditions is met: The transition layer is interpenetrated and bonded with the first inorganic layer and the heating layer; The heating layer contains metal elements, the content of the metal elements in the transition layer is greater than or equal to 0, and the content of the metal elements in the heating layer is greater than the content of the metal elements in the transition layer per unit area cross section; The heating layer and the transition layer both include silicon oxides, and the silicon content in the heating layer is less than that in the transition layer per unit area of ​​the cross section; The heating layer, the transition layer, and the bonding layer all include silicon oxides. In a unit cross-section, the silicon content in the heating layer is less than that in the transition layer, and the silicon content in the bonding layer is greater than that in the transition layer. A glass phase is formed in the transition layer, the melting temperature of the glass phase in the bonding layer is not greater than the melting temperature of the glass phase in the transition layer, and the melting temperature of the glass phase in the transition layer is not higher than 800° C.; The thickness of the transition layer is not greater than the thickness of the heating layer; The orthographic projection of the heating layer on the transition layer is located inside the transition layer.

9. The heating element assembly according to claim 8, characterized in that: At least one of the following conditions is met: The metal elements in the transition layer and the heating layer are of the same type, and the glass phases in the transition layer and the heating layer are of the same type; The heating layer comprises no less than 70 wt % of metal elements; The heating layer includes a magnetically sensitive metal element with a relative magnetic permeability less than 1; The metal element comprises at least one selected from the group consisting of silver, copper and aluminum; The thickness of the transition layer is 0.1-5 μm.

10. A method for preparing the heating element assembly according to any one of claims 1 to 9, characterized in that: include: (1) forming a heating layer on the first inorganic layer using a heating layer slurry, and forming a bonding layer on the heating layer using a bonding layer slurry; (2) Sintering the first inorganic layer formed with the heating layer and the bonding layer and the second inorganic layer so that the first inorganic layer and the second inorganic layer are bonded to each other, thereby obtaining the heating element assembly.

11. The method according to claim 10, characterized in that Step (1) further includes: (1-1) printing the heating layer slurry on the first inorganic layer and drying or sintering it; (1-2) printing the bonding layer slurry on the heating layer obtained by drying or sintering it and sintering it.

12. The method according to claim 11, characterized in that The sintering temperatures in step (1) and step (2) are independently 550-650°C.

13. The method according to any one of claims 10 to 12, characterized in that Before performing step (1), the method further includes: printing a transition layer slurry on the first inorganic layer and drying or sintering the slurry; in step (1), forming the heating layer on the transition layer obtained by drying or sintering.

14. A heatable dish, characterized in that: The invention comprises a heating element assembly according to any one of claims 1 to 9 or a heating element assembly made by the method according to any one of claims 10 to 12.

15. The heatable vessel according to claim 14, wherein: At least one of the following conditions is met: The heating element assembly is arranged at the bottom of the heatable dish; The heatable vessel comprises a side wall and a bottom wall that are sealed together, and at least a portion of the bottom wall is the heating element assembly; The heatable vessel is made of glass-ceramic, borosilicate glass or ceramic.

16. The heatable vessel according to claim 15, wherein: The side wall and the bottom wall define a cavity for the heatable vessel, and an average thickness of the heating element assembly is smaller than an average thickness of the side wall.

17. The heatable vessel according to claim 15 or 16, characterized in that The heating element assembly is connected to the side wall by fusion welding, and the fusion welding is achieved by the following steps: (i) preheating the heating element assembly; (ii) welding the edge of the preheated heating element assembly and the side wall using a heat source; and (iii) annealing the welded vessel.

18. The heatable vessel according to claim 17, wherein: The preheating temperature is 300-600°C, and the annealing temperature is 500-700°C.

19. An electrical appliance, characterized in that: A heatable dish according to any one of claims 14 to 18.

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