Cookware and method of manufacturing the same

Abstract

The present invention provides a cookware and a method for manufacturing the same. The cookware comprises a base material, a first ceramic powder thermal insulation coating applied to the inner surface of the base material, a non-stick coating applied over the first ceramic powder thermal insulation coating, a second ceramic powder thermal insulation coating applied to the outer surface of the base material, and a high-temperature resistant paint coating applied over the second ceramic powder thermal insulation coating. This cookware reduces the heat transfer rate of the cookware without significantly increasing the thickness of the base material, resulting in more uniform heating.

Description

Technical Field

[0001] The present invention relates to the field of kitchenware, and more particularly to a cookware and a manufacturing method thereof. Background Art

[0002] Existing smokeless cookware typically achieves the goal of keeping cooking temperatures low and eliminating smoke by reducing thermal conductivity. This can be achieved by selecting a pot material with low thermal conductivity and increasing the pot thickness. However, this has some drawbacks. For example, iron and stainless steel pots have low thermal conductivity but high density, and a thickness exceeding 1mm makes the pot heavy and difficult to hold. Aluminum pots have high thermal conductivity and low density, so they need to be made very thick (for example, over 3.5mm), which also makes the pot heavy. Summary of the Invention

[0003] Therefore, the present invention aims to solve the above-mentioned problems existing in the prior art. More specifically, the present invention aims to provide a cookware and a manufacturing method thereof that can effectively achieve a smoke-free effect without significantly increasing the thickness of the cookware.

[0004] According to one aspect of the present invention, a cookware is provided, comprising a cookware body substrate, a first ceramic powder thermal insulation coating applied on the inner surface of the cookware body substrate, a non-stick coating applied on the first ceramic powder thermal insulation coating, a second ceramic powder thermal insulation coating applied on the outer surface of the cookware body substrate, and a high-temperature resistant paint coating applied on the second ceramic powder thermal insulation coating. The thermal conductivity of the ceramic powder thermal insulation coating is significantly lower than that of the cookware body substrate, and thus the heat transfer rate of the cookware can be reduced without significantly increasing the thickness of the cookware body substrate, thereby making the heating more uniform. In addition, by applying a non-stick coating on the thermal insulation coating on the inner surface of the cookware body substrate, the non-stick property of the cookware can be increased, and by spraying a high-temperature resistant paint coating on the outer surface of the cookware body substrate, the cookware can be made more resistant to high temperatures, thereby preventing the cookware from overheating due to excessive temperatures.

[0005] Preferably, each of the first ceramic powder insulation coating and the second ceramic powder insulation coating may include yttria-stabilized zirconia powder. Yttria-stabilized zirconia powder has the advantages of high hardness, high wear resistance, low thermal conductivity, corrosion resistance, high temperature resistance, excellent thermal insulation performance, and low thermal expansion coefficient. When the yttria-stabilized zirconia powder is coated on the inner and outer surfaces of the pot body substrate of the cookware, on the one hand, the low thermal conductivity of the zirconia powder itself can reduce the rate of heat transfer to the cookware. On the other hand, the zirconia powder coating has a certain porosity, and the cavity air contained in the pores has a thermal conductivity close to that of a vacuum, which further reduces the heat transfer rate. Therefore, by coating the inner and outer surfaces of the pot body substrate of the cookware with yttria-stabilized zirconia powder, the overall thermal conductivity of the cookware can be effectively reduced, thereby achieving a smoke-free effect for the entire cookware. This can be achieved without increasing the pot body substrate and can even minimize the thickness of the pot body substrate, thereby providing an optimal end-holding experience.

[0006] Preferably, the mass ratio of zirconium oxide to yttrium oxide in each of the first and second ceramic powder insulation coatings is between 95:5 and 90:10. That is, the yttrium oxide addition range is between 5% and 10%. More preferably, the mass ratio of zirconium oxide to yttrium oxide in each of the first and second ceramic powder insulation coatings is between 94:6 and 92:8. Pure zirconium oxide is unstable at room temperature, so adding a small amount of yttrium oxide can transform the zirconium oxide into a stable or metastable state, thereby imparting heat resistance, corrosion resistance, and ceramic toughening properties. If the yttrium oxide addition ratio is low, for example, a zirconium oxide to yttrium oxide mass ratio greater than 95:5 (i.e., adding 5% yttrium oxide), the stabilization effect is poor. If the yttrium oxide addition ratio is high, for example, a zirconium oxide to yttrium oxide mass ratio less than 90:10 (i.e., adding 10% yttrium oxide), the properties of the zirconium oxide itself are affected and the cost is increased.

[0007] Preferably, at the bottom of the cookware and within a first height range of 40 mm below the bottom, the thickness of the first ceramic powder thermal insulation coating and the second ceramic powder thermal insulation coating may be 50 μm to 80 μm, respectively.

[0008] Preferably, within a second height range of more than 40 mm from the bottom of the pot, the film thickness of the first ceramic powder insulation coating and the second ceramic powder insulation coating can be 30 μm to 50 μm respectively. Adjusting the film thickness of the ceramic powder insulation coating according to different coating ranges of the ceramic powder insulation coating can optimize the utilization rate of the ceramic powder insulation coating. For example, at the bottom of the pot and within a height range of less than 40 mm from the bottom, that is, the bottom and lower part of the pot, this part is closer to the fire source, so the sprayed insulation coating is thicker. Within a height range of more than 40 mm from the bottom of the pot, that is, the middle or upper part of the pot, this part is farther from the fire source, and the insulation coating is relatively thinner, which fully optimizes the coating of the insulation coating and effectively reduces the cost of the pot. In addition, the coating range of the insulation coating can be adjusted according to different pot shapes, capacities, functions, etc. On the one hand, it ensures excellent coating insulation performance and coating stability (for example, avoiding the risk of coating collapse), and on the other hand, it does not affect cooking efficiency too much.

[0009] According to another aspect of the present invention, a method for manufacturing a cookware is provided, comprising: preparing a cookware body; spraying a first ceramic powder thermal insulation coating on the inner surface of a base material of the cookware body and a second ceramic powder thermal insulation coating on the outer surface of the base material using a plasma spraying process; spraying a non-stick coating on the first ceramic powder thermal insulation coating, and spraying a high-temperature resistant paint coating on the second ceramic powder thermal insulation coating. The plasma spraying process achieves the beneficial effects of uniform coating and reduced oxidation.

[0010] Preferably, the plasma spraying step may include: spraying yttria-stabilized zirconia ceramic powder onto the inner surface and the outer surface of the pot body substrate to form the first ceramic powder thermal insulation coating and the second ceramic powder thermal insulation coating, respectively.

[0011] Preferably, the plasma spraying step may include: (1) sandblasting the surface of the pot body substrate to be sprayed; (2) loading yttria-stabilized zirconia powder of 300 to 1000 mesh into a powder feeder; (3) spraying under the conditions of a powder feeding rate of 10 g / min-40 g / min, a spraying distance of 140 mm to 160 mm, an arc current of 450 A-650 A, a hydrogen pressure of 0.4 MPa-0.9 MPa, a hydrogen flow rate of 5 L / min-10 L / min, an argon pressure of 0.4 MPa-0.9 MPa, and an argon flow rate of 35 L / min-80 L / min. Under these parameters, the high-pressure plasma flame flow at the muzzle of the plasma spraying device can heat the yttria-stabilized zirconia powder to melt, and then deposit it on the surface of the pot body substrate, thereby forming a thermal barrier coating.

[0012] Preferably, within the first height range of the cookware, the first ceramic powder thermal insulation coating and the second ceramic powder thermal insulation coating can be controlled to have a first film thickness, respectively; within the second height range of the cookware, the first ceramic powder thermal insulation coating and the second ceramic powder thermal insulation coating can be controlled to have a second film thickness different from the first film thickness.

[0013] Preferably, within the bottom of the cookware and within a first height range of less than 40 mm from the bottom, the film thicknesses of the first ceramic powder thermal insulation coating and the second ceramic powder thermal insulation coating can be controlled to be 50 μm to 80 μm, respectively; within a second height range of more than 40 mm from the bottom of the cookware, the film thicknesses of the first ceramic powder thermal insulation coating and the second ceramic powder thermal insulation coating can be controlled to be 30 μm to 50 μm, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A partial cross-sectional view of a cookware according to an embodiment of the present invention is schematically shown.

[0015] Description of reference numerals:

[0016] 1- pot body base material; 2- first ceramic powder heat-insulating coating; 3- second ceramic powder heat-insulating coating; 4- non-stick coating; 5- high temperature resistant paint coating. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the technical concept of the present invention, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals always represent the same components.

[0018] The reason why household smokeless pots have a smokeless effect is that the temperature of the bottom of the pot is controlled within 220℃ within a certain period of time. This is because the cracking temperature of ordinary cooking oil is 220℃~240℃. As long as the temperature of the bottom of the pot exceeds this temperature, smoke will definitely be produced.

[0019] The main heat transfer method of the pot is heat conduction, according to the flat wall heat conduction formula:

[0020]

[0021] Where Q is the heat transfer amount; λ is the thermal conductivity of the material; b is the wall thickness; S is the heat transfer area; t1 is the high temperature surface temperature; t2 is the low temperature surface temperature;

[0022] Formula (1) can be transformed into

[0023] Because this model only studies the temperature change along the thickness of the plate, formula (2) is simplified to the heat transfer per unit area of the plate (let S = 1), and the heat transfer amount Q is expressed by the heat transfer rate q and the heat transfer time T to obtain the following formula:

[0024]

[0025] Formula (3) shows that the pot bottom is heated by an external heat source, where t2 is the pot bottom inner wall temperature and t1 is the pot bottom outer wall temperature. The physical meaning of the left side of the formula is the heating rate, and the variables on the right side of the formula related to the pot body design are the pot bottom thickness, pot bottom area, and the pot body material thermal conductivity. Using the single variable method, we can see that, with other parameters unchanged, the larger b (i.e., the thicker the pot bottom), the smaller t2 (the lower the pot wall temperature for the same heating time); the smaller λ (using a material with a lower thermal conductivity coefficient), the smaller t2 (the lower the pot wall temperature for the same time).

[0026] The present invention proposes coating the inner and outer surfaces of the pot body substrate with a ceramic powder heat-insulating coating having low thermal conductivity to reduce the heat transfer rate, avoid excessive temperature of the pot body, and thereby achieve a smoke-free effect.

[0027] like Figure 1 As shown, the cookware proposed by the present invention includes a cookware base material 1, a first ceramic powder thermal insulation coating 2 applied to the inner surface of the cookware base material 1, and a second ceramic powder thermal insulation coating 3 applied to the outer surface of the cookware base material 1. Here, the ceramic powder material can be sprayed onto the inner and outer surfaces of the cookware base material 1 using a thermal spraying process (e.g., a plasma spraying process). Here, the cookware base material 1 is the main body material that forms the overall shape of the cookware. For example, the cookware base material 1 can include aluminum, stainless steel, iron, etc.

[0028] In this embodiment, each of the first ceramic powder thermal insulation coating 2 and the second ceramic powder thermal insulation coating 3 may include yttria-stabilized zirconia powder. The thermal conductivity of air is approximately 0.023 W / mK, the thermal conductivity of zirconia ceramic powder is approximately 2.09 W / mK, and the thermal conductivity of aluminum, which can be used as a base material for a pot body, is approximately 237 W / mK. This indicates that the thermal conductivity of zirconia ceramic powder and air is significantly lower than that of aluminum, which can typically be used as a base material for a pot body. When yttria-stabilized zirconia powder is coated on the inner and outer surfaces of the pot body substrate of the cookware, on the one hand, the low thermal conductivity of the zirconia powder itself can reduce the speed of heat transfer to the cookware. On the other hand, there is a certain porosity in the zirconia powder coating, and the cavity air contained in the pores has a thermal conductivity close to that of a vacuum, which further reduces the heat transfer speed. Therefore, by coating yttria-stabilized zirconia powder on the inner and outer surfaces of the pot body substrate of the cookware, the overall thermal conductivity of the cookware can be effectively reduced, thereby achieving a smoke-free effect for the entire cookware. This can be done without increasing the pot body substrate, and the thickness of the pot body substrate can even be minimized, thereby obtaining the best end-holding experience.

[0029] In addition, yttria-stabilized zirconia powder also has the advantages of high hardness, high wear resistance, corrosion resistance, and low thermal expansion coefficient.

[0030] As described above, each of the first ceramic powder thermal insulation coating 2 and the second ceramic powder thermal insulation coating 3 may include yttria-stabilized zirconia powder, which may be a nanopowder. Pure zirconia is unstable at room temperature, so by adding a small amount of yttria, zirconia can be transformed into a stable or metastable state, thereby having the characteristics of heat resistance, corrosion resistance, and ceramic toughening. Preferably, the addition range of yttria can be between 5% and 10%, that is, the mass ratio of zirconia to yttria in each of the first ceramic powder thermal insulation coating 2 and the second ceramic powder thermal insulation coating 3 is 95:5 to 90:10. More preferably, the mass ratio of zirconia to yttria in each of the first ceramic powder thermal insulation coating 2 and the second ceramic powder thermal insulation coating 3 can be 94:6 to 92:8. If the proportion of yttrium oxide added is low, for example, the mass ratio of zirconium oxide to yttrium oxide is greater than 95:5 (i.e., 5% yttrium oxide is added), the stabilization effect is poor. If the proportion of yttrium oxide added is high, for example, the mass ratio of zirconium oxide to yttrium oxide is less than 90:10 (i.e., 10% yttrium oxide is added), the properties of zirconium oxide itself are affected and the cost is increased.

[0031] In addition, the present invention also proposes to further coat a non-stick coating or a high temperature resistant paint coating on the ceramic powder heat insulation coating. Figure 1 As shown, the cookware also includes a non-stick coating 4 applied on the first ceramic powder insulation coating 2 and a high-temperature resistant paint coating 5 applied on the second ceramic powder insulation coating 3. By applying the non-stick coating on the insulation coating on the inner surface of the pot body substrate, the non-stick properties of the cookware can be enhanced. The high-temperature resistant paint coating is sprayed on the outer surface of the pot body substrate, making the cookware more resistant to high temperatures and preventing the cookware from overheating due to excessive heat.

[0032] Yttria-stabilized zirconia powder can be prepared using methods such as hydrothermal, chemical coprecipitation, and sol-gel methods. However, the powder obtained by coprecipitation has poor dispersibility and severe agglomeration during dehydration. The sol-gel method has relatively harsh process conditions and expensive raw materials, making it unsuitable for large-scale industrial production. Therefore, the hydrothermal method is preferred for preparing the powder due to its simple process and low cost, which is conducive to industrial production. The powder is then post-treated to form a stable sol that can be directly used for coating spraying.

[0033] Yttria-stabilized zirconia powder can be sprayed onto the inner and outer surfaces of the pot body substrate by a thermal spraying process. For example, the thermal spraying process may include plasma spraying, flame spraying, and arc spraying core wire. Plasma spraying is preferably used, which has a uniform coating and less oxidation.

[0034] Specifically, the method for manufacturing the cookware provided by the present invention may include the following steps.

[0035] First, a pot body is prepared, i.e., a pot body having a specific pot body shape is prepared. Then, a first ceramic powder thermal insulation coating is sprayed onto the inner surface of a pot body substrate and a second ceramic powder thermal insulation coating is sprayed onto the outer surface of the pot body substrate using a plasma spraying process. Preferably, the plasma spraying step may include spraying yttria-stabilized zirconia ceramic powder onto the inner and outer surfaces of the pot body substrate to form the first and second ceramic powder thermal insulation coatings, respectively.

[0036] Preferably, the plasma spraying step may include: (1) sandblasting the surface of the pot body substrate to be sprayed to pre-treat the substrate surface, clean the pot body substrate surface, and roughen the substrate surface so that the subsequently sprayed thermal insulation coating can be more firmly bonded to the pot body substrate; (2) loading 300-1000 mesh yttria-stabilized zirconia powder into a powder feeder, wherein the particle size range of the yttria-stabilized zirconia powder selected here is 300-1000 mesh spherical powder. Powders below 300 mesh require longer melting time, which increases process costs. Insufficient powder melting will lead to a decrease in deposition rate. Powders above 1000 mesh are prone to moisture absorption and agglomeration, which is easy to clog the gun during spraying; (3) when the powder feeding speed is 10g / min-40g / min and the spraying distance is The spraying is carried out under the conditions of 140mm to 160mm, arc current of 450A-650A, hydrogen pressure of 0.4MPa-0.9MPa, hydrogen flow rate of 5L / min-10L / min, argon pressure of 0.4MPa-0.9Mpa, and argon flow rate of 35L / min-80L / min. Under these parameters, the high-pressure plasma flame flow at the muzzle of the plasma spraying device can heat the yttria-stabilized zirconia powder to melting, and then deposit it on the surface of the pot body substrate to form a thermal insulation coating. The film thickness of the thermal insulation coating can be 80μm to 200μm. If the coating film thickness is too small, the heat resistance effect is not obvious. If the coating film thickness is too large, it may bring the risk of cracking due to excessive internal stress, and the spraying time is long, the material consumption is high, and the cost is increased.

[0037] Here, the thickness of the thermal insulation coating can be made different in different areas of the cookware. For example, within a first height range of the cookware (e.g., the portion closer to the fire source), the first ceramic powder thermal insulation coating on the inner surface of the pot body substrate and the second ceramic powder thermal insulation coating on the outer surface of the cookware can each have a first film thickness, and within a second height range of the cookware (e.g., the portion farther from the fire source), the first ceramic powder thermal insulation coating and the second ceramic powder thermal insulation coating can each have a second film thickness different from the first film thickness, for example, the second film thickness can be less than the first film thickness.

[0038] For example, at the bottom of the cookware and within the first height range of 40 mm below the bottom, that is, the bottom and lower part of the cookware, this part is closer to the fire source, so the sprayed thermal insulation coating is thicker, and the film thickness of the first ceramic powder thermal insulation coating and the second ceramic powder thermal insulation coating can be controlled to be 50 μm to 80 μm respectively (for example, in the case where the cookware is a frying pan). In this case, when the film thickness is less than 50 μm, the thermal insulation performance of the coating is poor; when the film thickness is greater than 80 μm, the bottom is heated by an open flame due to the thermal insulation effect of the coating, and the heat energy of the open flame is transmitted too slowly, affecting the cooking efficiency, and under the action of the internal stress of the thermal insulation coating, there is a risk of coating collapse. Within the second height range of the cookware, which is more than 40 mm from the bottom, that is, the middle or upper part of the cookware, this part is far away from the fire source, and the thermal insulation coating is relatively thin. This fully optimizes the coating of the thermal insulation coating and effectively reduces the cost of the cookware. For this part, the film thickness of the first ceramic powder thermal insulation coating and the second ceramic powder thermal insulation coating can be controlled to be 30μm to 50μm, respectively. In this case, when the coating film thickness is less than 30μm, the process is more difficult to implement. When the film thickness is greater than 50μm, the heat transferred 40 mm away from the bottom of the pot body is less, the required thermal insulation function is not effectively used, and the cost is increased.

[0039] Furthermore, a ceramic powder thermal insulation coating can be sprayed onto a portion of the inner and / or outer surfaces of the pot body substrate, and the thickness of the ceramic powder thermal insulation coating to be sprayed can be determined based on the area of the sprayed ceramic powder thermal insulation coating. In other words, the coating range of the thermal insulation coating can be adjusted to suit different pot shapes, capacities, functions, etc., and the film thickness of the ceramic powder thermal insulation coating can be adjusted based on the coating range. This optimizes the utilization of the ceramic powder thermal insulation coating and ensures excellent thermal insulation performance and coating stability (for example, avoiding the risk of coating collapse) without significantly affecting cooking efficiency.

[0040] After the inner and outer insulation coatings are sprayed, a non-stick coating (for example, fluorine coating) can be further sprayed on the first ceramic powder insulation coating to increase the non-stick property of the cookware, and a high-temperature resistant paint coating can be sprayed on the second ceramic powder insulation coating to make the cookware more resistant to high temperatures and prevent the cookware from overheating due to excessive temperatures, ultimately obtaining a smokeless cookware.

[0041] The above describes in detail the specific embodiments of the present invention. Although some embodiments have been shown and described, those skilled in the art will appreciate that these embodiments may be combined, modified, and improved (for example, different technical features of the present invention may be combined to obtain new technical solutions) without departing from the principles and spirit of the present invention, the scope of which is defined by the claims. Such combinations, modifications, and improvements are also intended to fall within the scope of protection of the present invention.

Claims

1. A cookware, characterized in that: The cookware comprises a cookware base material (1), a first yttria-stabilized zirconia nanopowder thermal insulation coating (2) formed on the inner surface of the cookware base material (1), a non-stick coating (4) coated on the first yttria-stabilized zirconia nanopowder thermal insulation coating (2), a second yttria-stabilized zirconia nanopowder thermal insulation coating (3) formed on the outer surface of the cookware base material (1), and a high-temperature resistant paint coating (5) coated on the second yttria-stabilized zirconia nanopowder thermal insulation coating (3), wherein the first yttria-stabilized zirconia nanopowder thermal insulation coating (2) and the second yttria-stabilized zirconia nanopowder thermal insulation coating (3) are thermally stable. The thermal conductivity of the first yttria-stabilized zirconia nanopowder thermal insulation coating (2) and the second yttria-stabilized zirconia nanopowder thermal insulation coating (3) are respectively lower than the thermal conductivity of the pot body substrate (1), and are both used to reduce the heat transfer rate into the pot. At the bottom of the pot and within a first height range of 40 mm below the bottom, the first film thickness of the first yttria-stabilized zirconia nanopowder thermal insulation coating (2) and the second yttria-stabilized zirconia nanopowder thermal insulation coating (3) are respectively 50 μm to 80 μm. At a second height range of 40 mm above the bottom of the pot, the first yttria-stabilized zirconia nanopowder thermal insulation coating (2) and the second yttria-stabilized zirconia nanopowder thermal insulation coating (3) have a second film thickness different from the first film thickness.

2. The cookware according to claim 1, wherein: The mass ratio of zirconium oxide to yttrium oxide in each of the first yttria-stabilized zirconia nanopowder thermal insulation coating (2) and the second yttria-stabilized zirconia nanopowder thermal insulation coating (3) is 90:10 to 95:

5.

3. The cookware according to claim 2, characterized in that: The mass ratio of zirconium oxide to yttrium oxide in each of the first yttria-stabilized zirconia nanopowder thermal insulation coating (2) and the second yttria-stabilized zirconia nanopowder thermal insulation coating (3) is 92:8 to 94:

6.

4. The cookware according to claim 1, wherein: The pot body base material (1) includes aluminum, stainless steel or iron.

5. The cookware according to any one of claims 1 to 4, characterized in that: In a second height range of the pot that is more than 40 mm from the bottom, the film thicknesses of the first yttria-stabilized zirconia nanopowder thermal insulation coating (2) and the second yttria-stabilized zirconia nanopowder thermal insulation coating (3) are respectively 30 μm to 50 μm.

6. A method for manufacturing a cookware, characterized in that: include: preparing a pot body; A first yttria-stabilized zirconia nanopowder thermal insulation coating (2) is sprayed on the inner surface of a pot body substrate of a pot body by a plasma spraying process, and a second yttria-stabilized zirconia nanopowder thermal insulation coating (3) is sprayed on the outer surface of the pot body substrate, wherein the thermal conductivity of the first yttria-stabilized zirconia nanopowder thermal insulation coating (2) and the second yttria-stabilized zirconia nanopowder thermal insulation coating (3) are respectively lower than the thermal conductivity of the pot body substrate (1), and both are used to reduce the heat transfer rate into the pot, at the bottom of the pot and within a first height range of less than 40 mm from the bottom, the first film thickness of the first yttria-stabilized zirconia nanopowder thermal insulation coating (2) and the second yttria-stabilized zirconia nanopowder thermal insulation coating (3) are respectively 50 μm to 80 μm, and within a second height range of more than 40 mm from the bottom of the pot, the first yttria-stabilized zirconia nanopowder thermal insulation coating and the second yttria-stabilized zirconia nanopowder thermal insulation coating have a second film thickness different from the first film thickness; A non-stick coating is sprayed on the first yttria-stabilized zirconia nanopowder thermal insulation coating, and a high-temperature resistant paint coating is sprayed on the second yttria-stabilized zirconia nanopowder thermal insulation coating.

7. The method for manufacturing a cookware according to claim 6, wherein: The plasma spraying step includes spraying yttria-stabilized zirconia ceramic nanopowder onto the inner surface and outer surface of the pot body substrate to form the first yttria-stabilized zirconia nanopowder thermal insulation coating and the second yttria-stabilized zirconia nanopowder thermal insulation coating respectively.

8. The method for manufacturing a cookware according to claim 7, wherein: Plasma spraying steps include: (1) sandblasting the surface of the pot body substrate to be sprayed; (2) Loading yttria-stabilized zirconia powder into a powder feeder; (3) Spraying is carried out under the conditions of powder feeding speed of 10g / min-40g / min, spraying distance of 140mm to 160mm, arc current of 450A-650A, hydrogen pressure of 0.4MPa-0.9MPa, hydrogen flow rate of 5L / min-10L / min, argon pressure of 0.4MPa-0.9Mpa, and argon flow rate of 35L / min-80L / min.

9. The method for manufacturing a cookware according to claim 6, wherein: In a second height range of the cookware that is more than 40 mm from the bottom, the thicknesses of the first yttria-stabilized zirconia nanopowder thermal insulation coating and the second yttria-stabilized zirconia nanopowder thermal insulation coating are respectively 30 μm to 50 μm.

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