Composite cookware and preparation method thereof

Abstract

The present invention relates to the field of cookware, and discloses a composite cookware and a preparation method thereof. The composite cookware comprises, from the inside to the outside, a ceramic inner liner (1), an aluminum-containing coating (2), an aluminum welding layer (3) and a metal outer shell (4). The method for preparing the composite cookware comprises: (1) spraying the aluminum-containing coating on the outer surface of the ceramic inner liner; (2) coating the aluminum-containing coating and the inner side of the metal outer shell with a brazing flux and a solder, so as to connect the ceramic inner liner and the metal outer shell by furnace brazing. The ceramic inner liner of the cookware of the present invention is tightly combined with the metal outer shell, and has the characteristics of being healthy and environmentally friendly like ceramic cookware, and being not easy to break like metal cookware and being suitable for electromagnetic heating and pressure cookers. Therefore, the composite cookware of the present invention is healthy and environmentally friendly, does not have the risk of metal element dissolution during long-term contact with food, is not easy to break, and can be used for electromagnetic heating and pressure cookers.

Description

Technical Field

[0001] The invention relates to the field of cookware, and in particular to a composite cookware and a preparation method thereof. Background Art

[0002] In recent years, as people's living standards have been getting higher and higher, the requirements for healthy and environmentally friendly cookware materials have been getting higher and higher, and there has been increasing concern about problems such as rust and poisoning of metal cookware. Due to the superior performance of ceramic materials, they are healthy and environmentally friendly, resistant to chemical corrosion, and have no risk of metal element dissolution during long-term contact with food. They also have a certain far-infrared penetration function, which ensures the deliciousness of food. Their application in the field of cookware has received more and more attention. However, ceramic materials do not have electromagnetic heating function, the material is relatively brittle and easy to fall and break, and there are safety risks when using ceramic pots in pressure cookers.

[0003] At present, it is impossible to achieve effective close bonding between ceramics and metals, so the heat transfer effect of conventional metal-ceramic composite cookware is poor. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem of limited application of ceramic pots or metal pots in the prior art and to provide a composite pot and a preparation method thereof.

[0005] In order to achieve the above-mentioned object, the present invention provides a composite cookware, which comprises, from the inside to the outside, a ceramic inner pot, an aluminum-containing coating, an aluminum welding layer and a metal outer shell.

[0006] A second aspect of the present invention provides a method for preparing a composite cookware, the method comprising the following steps:

[0007] (1) spraying an aluminum coating on the outer surface of the ceramic liner;

[0008] (2) Coating flux and solder on the inner side of the aluminum coating and the metal shell to connect the ceramic liner and the metal shell by brazing.

[0009] Through the above technical scheme, the ceramic inner liner of the cookware of the present invention is tightly combined with the metal outer shell, which has the characteristics of being healthy and environmentally friendly like ceramic cookware and not easy to break like metal cookware and being suitable for electromagnetic heating and pressure cookers. Therefore, the composite cookware of the present invention is healthy and environmentally friendly, has no risk of metal element dissolution during long-term contact with food, is not easy to break, has good heat conductivity, and can be used for electromagnetic heating and pressure cookers. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic structural diagram of a composite cookware according to an embodiment of the present invention.

[0011] Description of Reference Numerals

[0012] 1 Ceramic liner 2 Contains aluminum coating

[0013] 3 Aluminum welding layer 4 Metal shell DETAILED DESCRIPTION

[0014] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0015] like Figure 1 As shown, the composite cookware provided by the present invention includes a ceramic inner pot 1, an aluminum-containing coating 2, an aluminum welding layer 3 and a metal shell 4 from the inside to the outside. Among them, the cookware usually exists in the form of a container. Therefore, those skilled in the art can understand that the "inside" in "from the inside to the outside" refers to the inside that is in direct contact with the items to be contained (such as food), and the "outside" refers to the outside of the cookware. When the composite cookware provided by the present invention is used, the ceramic inner pot is in direct contact with the items to be contained (such as food), and the metal shell is arranged on the outermost side.

[0016] According to the present invention, based on health and environmental protection considerations, the material of the ceramic liner 1 is daily-use ceramics. Daily-use ceramics are usually made of porcelain stone, kaolin, quartz stone, and mullite by high-temperature firing. Generally, the composition of the daily-use ceramics is: 5-35% by weight of Al2O3, 30-75% by weight of SiO2, 3-10% by weight of Fe2O3, 2-10% by weight of CaO, 2-8% by weight of BaO, and 1-3% by weight of other oxides, wherein the other oxides are at least one of Na2O, K2O, MgO, and ZnO. Alternatively, the daily-use ceramics are industrial ceramics such as pure Al2O3 or ZrO2 (usually containing a small amount of oxide impurities, such as Na2O, K2O, MgO, and ZnO).

[0017] According to the present invention, the aluminum-containing coating 2 can be tightly combined with the ceramic liner, and can usually be coated on the outside of the ceramic liner by conventional spraying methods (such as thermal spraying). Preferably, the material of the aluminum-containing coating is aluminum and / or aluminum alloy.

[0018] According to the present invention, the aluminum solder layer 3 can make the aluminum-containing coating and the metal shell tightly bonded, so that more effective heat transfer can be achieved between the ceramic liner and the metal shell. Preferably, the aluminum solder layer is obtained by brazing aluminum solder (such as aluminum solder powder) and brazing agent, that is, the aluminum solder layer is a layer structure (brazing layer) formed by brazing. The specific types of aluminum solder and brazing agent can be conventionally selected, as can the specific steps and conditions of brazing.

[0019] According to the present invention, the metal shell 4 can be formed of various conventional metals. Preferably, the metal shell is made of stainless steel, iron, aluminum, titanium (or its alloy), copper (or its alloy) or aluminum alloy.

[0020] According to the present invention, there is no particular limitation on the thickness of each layer structure in the composite cookware.

[0021] Preferably, the thickness of the ceramic liner 1 is 3-8 mm, more preferably 4-6 mm.

[0022] Preferably, the thickness of the aluminum-containing coating 2 is 0.1-0.5 mm, more preferably 0.2-0.4 mm.

[0023] Preferably, the thickness of the aluminum solder layer 3 is 50-200 μm, more preferably 100-150 μm.

[0024] Preferably, the thickness of the metal shell 4 is 0.8-3 mm, more preferably 1.5-2 mm.

[0025] According to the present invention, the purpose of the present invention can be achieved as long as the above-mentioned layer structures are arranged in sequence from the inside to the outside. However, in a preferred case, the ceramic inner pot 1 extends outward along the pot mouth to form a pot edge, and the metal shell 4 is U-shaped, and the pot edge shields the upper end surface of the metal shell. This arrangement can ensure that the part of the composite cookware that directly contacts the items to be contained (such as food) is only the ceramic inner pot, and the health and safety of use are higher. In addition, such a structural design can make the cookware more beautiful on the one hand, and can also effectively prevent the end surface of the metal shell from corrosion or rust on the other hand.

[0026] The method for preparing a composite cookware provided by the present invention comprises the following steps:

[0027] (1) spraying an aluminum coating on the outer surface of the ceramic liner;

[0028] (2) Coating flux and solder on the inner side of the aluminum coating and the metal shell to connect the ceramic liner and the metal shell by furnace brazing (forming an aluminum solder layer).

[0029] The materials and thicknesses of the ceramic liner, the aluminum coating, the aluminum welding layer and the metal shell are as described above and will not be repeated here.

[0030] In the present invention, there is no particular requirement for the spraying method, but preferably, the spraying method in step (1) is thermal spraying, arc current: 100-300A (such as 100A, 120A, 140A, 150A, 160A, 200A, 250A, 300A or any value between the above values); spraying distance: 80-150mm (80mm, 90mm, 110mm, 120mm, 130mm, 150mm or any value between the above values); air pressure 0.5-1MPa (0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 1MPa or any value between the above values); voltage: 20-45V (20V, 25V, 32V, 35V, 38V, 40V, 45V or any value between the above values).

[0031] In the present invention, the solder is preferably aluminum brazing solder (such as aluminum solder powder), and the eutectic point of the solder is 500-650°C.

[0032] In the present invention, the brazing flux is preferably a brazing flux for aluminum. It can be a low melting point salt mixture of lithium chloride, sodium chloride, chloride salt or fluoride salt, such as LiCl-KCl-ZnCl2-NaF (QJ201, QJ202), LiCl-KCl-ZnCl2-SrCl2-LiF (QJ206), KCl-CaF2-NaCl-LiF-LiCl-ZnCl2 (QJ207), LiCl-KCl-NaCl-ZnCl2-NaF-AlF3-PbCl3 (Y-1) and L iCl-KCl-KF·AlF3 (YT17), which is generally used in the form of a solution dissolved in ethanol; it can also be a potassium fluoroaluminate mixed flux composed of KF-AlF3 system, specifically at least one of a eutectic flux of potassium fluoride and aluminum fluoride (such as QF), a LiCl-NaCl-KCl-ZnCl2-CdCl2-LiF flux (such as 129A) and a LiCl-NaCl-KCl-TiCl-LiF flux (such as 171B).

[0033] In the present invention, when the aluminum-containing coating and the metal shell are connected by brazing, the flux and the solder can be applied to the surface of the aluminum-containing coating and the metal shell in sequence, and then brazing (welding) is performed under a protective atmosphere (such as an ammonia atmosphere, which can be decomposed into nitrogen during the brazing process) or vacuum conditions. There are no special requirements for the method of applying the flux, which can be sprayed, brushed or immersed. There are no special requirements for the method of applying the solder, which can be sprayed or applied. The brazing temperature is preferably 600-750°C. The brazing time is preferably 15-60 minutes. The gas pressure providing the protective atmosphere during brazing is 0.25-0.35MPa.

[0034] In the present invention, the method may further include cleaning the ceramic liner and the metal shell with an organic solvent such as alcohol or acetone or a conventional cleaning agent, and further drying at 100-150° C. for 30-60 minutes after cleaning.

[0035] As mentioned above, according to a preferred embodiment of the present invention, the ceramic inner pot is arranged to extend outwardly along the pot mouth to form a pot edge, and the metal shell is U-shaped, and the pot edge shields the upper end surface of the metal shell.

[0036] The present invention will be described in detail below through examples.

[0037] Example 1

[0038] (1) Cleaning: The ceramic inner pot (material composition is Al2O3: 5 wt%, SiO2: 75 wt%, Fe2O3: 10 wt%, CaO: 2 wt%, BaO: 5 wt%, and the balance is other oxides (Na2O, K2O, MgO and ZnO)) and the metal shell (made of stainless steel) are cleaned with acetone, wherein the ceramic inner pot is arranged to extend outward along the pot mouth to form a pot edge, and the metal shell is U-shaped, and the pot edge shields the upper end surface of the metal shell;

[0039] Drying: Use an oven to dry the ceramic liner and metal shell at 150°C for 30 minutes;

[0040] (2) spraying an aluminum coating (made of aluminum) on the outer surface of the ceramic liner by thermal spraying, arc current: 100A, spraying distance: 80mm, air pressure: 0.5MPa, voltage: 20V;

[0041] (3) Applying flux QF (purchased from Huaheng Welding Material Manufacturing Co., Ltd., item number QJ208) on the aluminum-containing coating and the inner side of the metal shell;

[0042] (4) Solder coating: A layer of aluminum solder powder is coated on the outer surface of the ceramic liner (including aluminum coating) and the inner surface of the metal shell by powder coating. The solder powder mainly includes aluminum and silicon (purchased from Bowei Welding Co., Ltd., item number BW-4047F, eutectic point is about 580°C);

[0043] (5) Furnace welding: A continuous furnace is used for welding, the welding temperature is 600°C, the time is 15 minutes, and the ammonia pressure is 0.3 MPa.

[0044] Among them, the thicknesses of the ceramic liner, aluminum coating, aluminum welding layer and metal shell are 3mm, 0.1mm, 50μm and 0.8mm respectively.

[0045] According to the GB15066-2004 stainless steel pressure cooker standard test, the composite ceramic meets the requirements of 5.16 internal pressure resistance and 5.17 pressure relief pressure in the standard. The pressure used by the composite ceramic is 75KPa. By placing thermocouples at different positions on the bottom of the pot to measure the temperature points of different parts, it is found that the temperature difference at different points is less than 10°C, indicating that the composite inner pot is heated more evenly than the ceramic pot. The maximum temperature difference of a simple ceramic pot reaches 50°C, and the maximum temperature difference of a single stainless steel is also 30°C. The above test results show that the composite cookware of the present invention has good performance and is suitable for promotion and application.

[0046] Example 2

[0047] (1) Cleaning: A heat-resistant ceramic inner pot (material composition: Al2O3: 35 wt%, SiO2: 50 wt%, Fe2O3: 5 wt%, CaO: 5 wt%, BaO: 3 wt%, and the balance is other oxides (Na2O, K2O, MgO and ZnO)) and a metal shell (made of titanium) are cleaned with acetone, wherein the ceramic inner pot is arranged to extend outward along the pot mouth to form a pot edge, and the metal shell is U-shaped, and the pot edge shields the upper end surface of the metal shell;

[0048] Drying: Use an oven to dry the ceramic liner and metal shell at 150°C for 30 minutes;

[0049] (2) spraying an aluminum coating (made of aluminum) on the outer surface of the ceramic liner by thermal spraying, arc current: 150A, spraying distance: 120mm, air pressure: 0.7MPa, voltage: 35V;

[0050] (3) Applying flux QF (purchased from Huaheng Welding Material Manufacturing Co., Ltd., item number QJ208) on the aluminum-containing coating and the inner side of the metal shell;

[0051] (4) Solder coating: A layer of aluminum solder powder is coated on the outer surface of the ceramic liner (including aluminum coating) and the inner surface of the metal shell by powder coating. The solder powder mainly includes aluminum and silicon (purchased from Bowei Welding Co., Ltd., item number BW-4047F, eutectic point is about 580°C);

[0052] (5) Furnace welding: A continuous furnace is used for welding, the welding temperature is 600°C, the time is 20 minutes, and the ammonia pressure is 0.3 MPa.

[0053] Among them, the thicknesses of the ceramic liner, aluminum coating, aluminum welding layer and metal shell are 5mm, 0.3mm, 100μm and 2mm respectively.

[0054] According to the GB15066-2004 stainless steel pressure cooker standard test, the requirements of 5.16 internal pressure resistance and 5.17 pressure relief pressure in the standard are met. The pressure used by the composite ceramic is 105KPa. By placing thermocouples at different positions on the bottom of the pot to measure the temperature points of different parts, it is found that the temperature difference at different points is less than 5°C, indicating that the composite inner pot is heated more evenly than the ceramic pot. The maximum temperature difference of a simple ceramic pot reaches 50°C, and the maximum temperature difference of a single titanium pot is also 30°C. The above test results show that the composite cookware of the present invention has good performance and is suitable for promotion and application.

[0055] Example 3

[0056] (1) Cleaning: A pure Al2O3 ceramic inner pot (material composition is Al2O3: 97 wt% and other oxides (Na2O, K2O, MgO and ZnO)) and a metal shell (material is aluminum alloy) are cleaned with acetone respectively, wherein the ceramic inner pot is arranged to extend outward along the pot mouth to form a pot edge, and the metal shell is U-shaped, and the pot edge shields the upper end surface of the metal shell;

[0057] Drying: Use an oven to dry the ceramic liner and metal shell at 150°C for 30 minutes;

[0058] (2) Spraying an aluminum coating (made of aluminum) on the outer surface of the ceramic liner by thermal spraying, arc current: 300A, spraying distance: 150mm, air pressure: 1MPa, voltage: 45V.

[0059] (3) Applying flux QF (purchased from Huaheng Welding Material Manufacturing Co., Ltd., item number QJ208) on the aluminum-containing coating and the inner side of the metal shell;

[0060] (4) Solder coating: A layer of aluminum solder powder is coated on the outer surface of the ceramic liner (including aluminum coating) and the inner surface of the metal shell by powder coating. The solder powder mainly includes aluminum and silicon (purchased from Bowei Welding Co., Ltd., item number BW-4047F, eutectic point is about 580°C);

[0061] (5) Furnace welding: A continuous furnace is used for welding, the welding temperature is 600°C, the time is 30 minutes, and the ammonia pressure is 0.3 MPa.

[0062] Among them, the thicknesses of the ceramic liner, aluminum coating, aluminum welding layer and metal shell are 8mm, 0.5mm, 200μm and 3mm respectively.

[0063] According to the GB15066-2004 stainless steel pressure cooker standard test, the requirements of 5.16 internal pressure resistance and 5.17 pressure relief pressure in the standard are met. The pressure used by the composite ceramic is 115KPa. By placing thermocouples at different positions on the bottom of the pot to measure the temperature points of different parts, it is found that the temperature difference at different points is less than 5°C, indicating that the composite inner pot is heated more evenly than the ceramic pot. The maximum temperature difference of a simple ceramic pot reaches 50°C, and the maximum temperature difference of a single aluminum alloy pot is also 20°C. The above test results show that the composite cookware of the present invention has good performance and is suitable for promotion and application.

[0064] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A composite cookware, characterized in that: The composite cookware comprises, from the inside to the outside, a ceramic inner pot (1), an aluminum-containing coating (2), an aluminum welding layer (3) and a metal outer shell (4); Wherein, the aluminum-containing coating (2) has a thickness of 0.1-0.5 mm and is made of aluminum and / or aluminum alloy; The aluminum-containing coating (2) is applied to the outer side of the ceramic liner (1) by spraying; The thickness of the ceramic liner (1) is 3-8 mm, and the material is daily-use ceramics, wherein the daily-use ceramics are composed of: 5-35 wt% Al2O3, 30-75 wt% SiO2, 3-10 wt% Fe2O3, 2-10 wt% CaO, 2-8 wt% BaO, and 1-3 wt% other oxides, wherein the other oxides are at least one of Na2O, K2O, MgO, and ZnO; the thickness of the aluminum solder layer (3) is 50-200 μm, and is obtained by brazing aluminum solder and flux; the thickness of the metal shell (4) is 0.8-3 mm, and the material is stainless steel, iron, aluminum, titanium, copper, or aluminum alloy; The ceramic inner pot (1) extends outwards along the pot mouth to form a pot edge, and the metal shell (4) is U-shaped, and the pot edge covers the upper end surface of the metal shell.

2. A method for preparing the composite cookware according to claim 1, characterized in that: The method comprises the following steps: (1) Spraying an aluminum coating on the outer surface of the ceramic liner; (2) coating the aluminum-containing coating and the inner side of the metal shell with a brazing flux and a solder to connect the ceramic liner and the metal shell by furnace brazing; Wherein, the thickness of the aluminum-containing coating (2) is 0.1-0.5 mm; The thickness of the ceramic inner liner (1) is 3-8 mm; the thickness of the aluminum welding layer (3) is 50-200 μm; and the thickness of the metal outer shell (4) is 0.8-3 mm.

3. The method according to claim 2, wherein: The spraying method in step (1) is thermal spraying, arc current: 100-300A; spraying distance: 80-150mm; air pressure: 0.5-1MPa; voltage: 20-45V.

4. The method according to claim 2, wherein: The solder is aluminum brazing solder, and the eutectic point of the solder is 500-650°C.

5. The method according to claim 2, wherein: The brazing flux is a hard brazing flux for aluminum.

6. The method according to claim 2, wherein: The conditions for furnace brazing include: furnace temperature of 600-750°C, time of 15-60 minutes, and gas pressure of 0.25-0.35MPa for providing protective atmosphere.

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