Protective coating film for inner vessel of electric air fryer and coating method

Abstract

This invention discloses a protective coating and coating method for the inner liner of an electric air fryer. The coating comprises a composite film structure formed by alternately adding nano-waterborne coating and nano-organic ceramic coating to form a nano-waterborne coating and a nano-organic ceramic coating. Two coatings with a fixed thickness ratio are alternately coated on the inner liner surface using high-energy laser beam scanning and ultra-high-speed laser cladding technology. This invention, through the composite layer structure of alternating nano-waterborne coating and nano-organic ceramic coating, helps eliminate the layered structure of conventional coating surfaces, resulting in a smoother overall coating, reduced porosity, and improved overall coating durability. The newly added nano-waterborne coating effectively improves the breaking and rearrangement of key bond energies in the nano-organic ceramic coating, reducing hydrocarbon gas emissions and effectively suppressing the generation of irritating odors. Improvements to the nano-organic ceramic coating formulation increase the overall hardness and impact resistance of the inner liner surface coating, effectively addressing the problem of excessive brittleness in ceramic coatings.

Description

Technical Field

[0001] This invention relates to the field of kitchenware coating technology, and more specifically, to a protective coating and coating method for the inner liner of an electric air fryer. Background Technology

[0002] Common kitchen cookware with inner pots includes, but is not limited to, electric air fryers, rice cooker inner pots, electric pressure cookers, electric slow cookers, and electric saucepans. Previously, mainstream non-stick pans used Teflon (PFAS) as the main coating material to coat the inner pot or the surface of the pan. However, due to concerns about the harmful effects of PFAS on human health, it has been banned to some extent. Cookware manufacturers began to research new fluorine-free coatings. Currently, the mainstream inner pot materials include uncoated stainless steel, iron pots / refined iron / cast iron, ceramic / white porcelain / purple clay, as well as coated inner pots such as those with enamel coating, titanium ceramic / honeycomb titanium coating, and multi-layered composite inner pots. However, generally speaking, coated cookware inner pots are more durable.

[0003] Nano-ceramic coatings, a relatively new product promoted in recent years, are favored by businesses and consumers due to their high-temperature resistance, wear resistance, corrosion resistance, antibacterial properties, environmental friendliness, and aesthetic appeal. However, the operating environment of an air fryer differs slightly from other cookware. It operates in a completely enclosed space at high temperatures for a fixed period and comes into direct contact with large amounts of food oils. Although disposable paper trays or other utensils are used to collect oil and prevent contamination and splattering of the air fryer's inner liner, this protection is not complete. Therefore, the inner liner of an electric air fryer requires higher resistance to oils, corrosion, high temperatures, and high pressures. In addition, some marinated foods produce a noticeable pungent odor during the baking process, affecting food safety and the cooking experience. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a protective coating and coating method for the inner liner of an electric air fryer, thereby solving one or more of the above-mentioned problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: The protective coating of the inner liner of an electric air fryer includes a composite film structure in which nano-water-based coating and nano-organic ceramic coating are alternately applied to form a nano-water-based coating and a nano-organic ceramic coating, and the non-contact side of the inner liner is an organic ceramic coating. The formulation of the nano-waterborne coating includes dimethylsiloxane PDMS solution, xylene, silica sol, silicon nitride, FJ-14 powder, nano titanium carbide, and hydroxyl silicone oil; The formulation of nano-organic ceramic coatings includes cobalt sulfate, nickel sulfate, titanium boride, silicon boride, sodium molybdate, and a brightener.

[0006] Furthermore, the nano-aqueous coating is prepared by weight of 30-40 parts PDMS solution, 10-15 parts xylene, 12-18 parts silica sol, 5-10 parts silicon nitride, 5-10 parts FJ-14 powder, 4-12 parts nano titanium carbide and 7-8 parts hydroxyl silicone oil.

[0007] Furthermore, the PDMS solution has a molecular weight of 780~13400, a relative density of 0.92~0.97, and a molecular formula of [Si(CH3)2-O-]n.

[0008] Furthermore, the nano-organic ceramic coating is prepared by weight of 3-5 parts cobalt sulfate, 15-30 parts nickel sulfate, 12-20 parts titanium boride, 12-20 parts silicon boride, 7-8 parts sodium molybdate and 5-8 parts brightener.

[0009] Furthermore, cobalt sulfate, nickel sulfate, titanium boride, silicon boride, and sodium molybdate are all pre-ground powders with a particle size of 100-150 μm, and the brightener is a food-grade silicone oil brightener.

[0010] The steps for applying a protective coating to the inner liner of an electric air fryer are as follows: S1. Prepare nano-waterborne coatings and nano-organic ceramic coatings according to the formulations described in any one of claims 1 to 5; S2. After sanding the inner pot of the metal electric air fryer with sandpaper, ultrasonically clean it in petroleum ether for 10-15 minutes and dry it at room temperature. S3. Spray the nano-water-based coating and nano-organic ceramic coating onto the polished metal inner liner surface at a film thickness of 1:1 to 2:1. S3.1 Apply nano-water-based coating and let stand at room temperature for 1.5~2 hours; The coating is fed into an adiabatic furnace and filled with protective gas. A high-energy laser beam generated by a carbon dioxide laser is used to scan the coating. After air cooling, a single-layer nano-aqueous coating is obtained. S3.2. Take out the inner liner coated with nano-water-based coating under high temperature, apply nano-organic ceramic coating to the inner liner by ultra-high speed laser cladding, and cure at high temperature to obtain a single layer of nano-organic ceramic coating. S3.3 Repeat steps S3, S3.1 and S3.2 according to the production grade of the inner liner until the corresponding thickness is achieved; S4. Inspect the integrity and gloss of the coating on the inner liner surface.

[0011] Further, in step S1, the formulated amount of PDMS solution and xylene are thoroughly stirred and ultrasonically dispersed for 10-20 minutes; Silicon nitride, FJ-14 powder, and nano-titanium carbide were sequentially added into the cavity of the supersonic particle bombardment and thoroughly crushed. After being removed, a mixed solution of PDMS and xylene was added and mixed. The supersonic particle bombardment was set with a gas pressure of 1~1.2MPa, a jet velocity of 270~300m / s, a bombardment angle of 57°, and a bombardment duration of 3~5min. Silica sol and hydroxyl silicone oil are rapidly added during the mixing process, and the mixture is continuously stirred to obtain a nano-waterborne coating.

[0012] Further, in step S1, the prescribed amounts of titanium boride and silicon boride are added to a sufficient amount of water and fed into a material mixer for preparation and mixing; the mixing speed is 500~600 r / min and the mixing lasts for 15~20 min. Cobalt sulfate, nickel sulfate, sodium molybdate, and a brightener are added, followed by mixing of the blended materials. After washing with water, a nano-organic ceramic coating is obtained.

[0013] Furthermore, in step S3.1, the laser wavelength is 10.2~10.5μm, the scanning rate is 8~12mm / s, the laser power is 200w, and the overlap rate is 3~4%.

[0014] Furthermore, in step S3.3, at least two layers of nano-waterborne coating and nano-organic ceramic coating are alternately superimposed. The nano-waterborne coating is applied to the contact side of the inner liner, while the outermost layer of the non-contact side of the inner liner is always the nano-organic ceramic coating.

[0015] In summary, the present invention has the following beneficial effects: the composite layer structure of alternating superimposed nano-aqueous coating and nano-organic ceramic coating helps to eliminate the layered structure of conventional coating surfaces, making the overall composite coating smoother, reducing porosity, and improving the overall durability of the coating; the newly added nano-aqueous coating effectively improves the breaking and rearrangement of key bond energies in the nano-organic ceramic coating, reduces hydrocarbon gas emissions, and effectively suppresses the generation of irritating odors; the improvement of the nano-organic ceramic coating formulation increases the overall hardness and impact resistance of the inner liner surface coating, effectively improving the problem of excessive brittleness of ceramic coatings. Attached Figure Description

[0016] Figure 1 A process flow diagram for one embodiment of the present invention; Figure 2 A cross-sectional micrograph of the composite coating in one embodiment of the present invention; Figure 3 The image shows the test results of the coating surface hardness and impact resistance in one embodiment of the present invention. Detailed Implementation Example

[0017] The following is in conjunction with the appendix Figure 1-3The present invention will be described in further detail below.

[0018] The protective coating for the inner liner of an electric air fryer includes a composite film structure formed by alternately applying nano-waterborne coatings and nano-organic ceramic coatings to create a nano-waterborne coating and a nano-organic ceramic coating.

[0019] The nano-waterborne coating is prepared by weight of 35 parts PDMS solution, 12.5 parts xylene, 15 parts silica sol, 7.5 parts silicon nitride, 7.5 parts FJ-14 powder, 8 parts nano titanium carbide, and 7.5 parts hydroxyl silicone oil. The PDMS solution has a molecular weight of 12000, a relative density of 0.93, and the molecular formula [Si(CH3)2-O-]n.

[0020] The nano-organic ceramic coating is prepared by weight of 4 parts cobalt sulfate, 22.5 parts nickel sulfate, 16 parts titanium boride, 16 parts silicon boride, 7.5 parts sodium molybdate, and 6.5 parts brightener. Among these, cobalt sulfate, nickel sulfate, titanium boride, silicon boride, and sodium molybdate are all pre-coarsely ground powders with a particle size of 175 μm, and the brightener is a food-grade silicone oil brightener.

[0021] The steps for applying a protective coating to the inner liner of an electric air fryer are as follows: S1. Prepare nano-waterborne coatings and nano-organic ceramic coatings according to the formula; Stir the PDMS solution and xylene in the prescribed amount thoroughly and then ultrasonically disperse for 15 minutes. Silicon nitride, FJ-14 powder, and nano-titanium carbide were sequentially added into the cavity of the supersonic particle bombardment and thoroughly crushed. After being removed, a mixed solution of PDMS and xylene was added and mixed. The supersonic particle bombardment was set with a gas pressure of 1.1 MPa, a jet velocity of 285 m / s, a bombardment angle of 57°, and a bombardment duration of 4 min. Silica sol and hydroxyl silicone oil are rapidly added during the mixing process, and the mixture is continuously stirred to obtain a nano-waterborne coating.

[0022] Add sufficient water to the prescribed amounts of titanium boride and silicon boride, and put them into a material mixer for preparation and mixing; the mixing speed is 550 r / min, and the mixing lasts for 17.5 min; Cobalt sulfate, nickel sulfate, sodium molybdate, and a brightener are added, followed by mixing of the blended materials. After washing with water, a nano-organic ceramic coating is obtained.

[0023] S2. After sanding the inner pot of the metal electric air fryer with sandpaper, ultrasonically clean it in petroleum ether for 12.5 minutes and dry it at room temperature. S3. Spray the nano-water-based coating and nano-organic ceramic coating onto the polished metal inner liner surface at a film thickness of 1.5:1. S3.1 Apply nano-water-based coating and let stand at room temperature for 1.75 hours; The material is fed into an adiabatic furnace, filled with protective gas, and a high-energy laser beam generated by a carbon dioxide laser is used to scan the coating. After air cooling, a single-layer nano-aqueous coating is obtained. The laser wavelength is 10.3 μm, the scanning rate is 10 mm / s, the laser power is 200 W, and the overlap rate is 3.5%.

[0024] S3.2. Take out the inner liner coated with nano-water-based coating under high temperature, apply nano-organic ceramic coating to the inner liner by ultra-high speed laser cladding, and cure at high temperature to obtain a single layer of nano-organic ceramic coating. S3.3 Repeat steps S3, S3.1 and S3.2 according to the production grade of the inner liner until the corresponding thickness is achieved, and at least two layers of nano-water-based coating and nano-organic ceramic coating are alternately superimposed. The nano-water-based coating is applied to the contact side of the inner liner, and the outermost part of the non-contact side of the inner liner is always the nano-organic ceramic coating.

[0025] S4. Inspect the integrity and gloss of the coating on the inner liner surface. Example

[0026] The protective coating for the inner liner of an electric air fryer includes a composite film structure formed by alternately applying nano-waterborne coatings and nano-organic ceramic coatings to create a nano-waterborne coating and a nano-organic ceramic coating.

[0027] The nano-waterborne coating is prepared by weight of 30 parts PDMS solution, 10 parts xylene, 12 parts silica sol, 5 parts silicon nitride, 5 parts FJ-14 powder, 4 parts nano titanium carbide, and 7 parts hydroxyl silicone oil. The PDMS solution has a molecular weight of 780, a relative density of 0.92, and the molecular formula [Si(CH3)2-O-]n.

[0028] The nano-organic ceramic coating is prepared by weight of 3 parts cobalt sulfate, 15 parts nickel sulfate, 12 parts titanium boride, 12 parts silicon boride, 7 parts sodium molybdate, and 5 parts brightener. Among them, cobalt sulfate, nickel sulfate, titanium boride, silicon boride, and sodium molybdate are all pre-coarsely ground powders with a particle size of 100 μm, and the brightener is a food-grade silicone oil brightener.

[0029] The steps for applying a protective coating to the inner liner of an electric air fryer are as follows: S1. Prepare nano-waterborne coatings and nano-organic ceramic coatings according to the formula; Stir the PDMS solution and xylene in the prescribed amount thoroughly and then ultrasonically disperse for 10 minutes. Silicon nitride, FJ-14 powder, and nano-titanium carbide were sequentially added into the cavity of the supersonic particle bombardment and thoroughly crushed. After being removed, a mixed solution of PDMS and xylene was added and mixed. The supersonic particle bombardment was set with a gas pressure of 1 MPa, a jet velocity of 270 m / s, a bombardment angle of 57°, and a bombardment duration of 3 min. Silica sol and hydroxyl silicone oil are rapidly added during the mixing process, and the mixture is continuously stirred to obtain a nano-waterborne coating.

[0030] Add sufficient water to the prescribed amounts of titanium boride and silicon boride, and put them into a material mixer for preparation and mixing; the mixing speed is 500 r / min, and the mixing lasts for 15 minutes; Cobalt sulfate, nickel sulfate, sodium molybdate, and a brightener are added, followed by mixing of the blended materials. After washing with water, a nano-organic ceramic coating is obtained.

[0031] S2. After sanding the inner pot of the metal electric air fryer with sandpaper, ultrasonically clean it in petroleum ether for 10 minutes and dry it at room temperature. S3. Spray the nano-water-based coating and nano-organic ceramic coating onto the polished metal inner liner surface at a film thickness of 1:1. S3.1 Apply nano-water-based coating and let stand at room temperature for 1.5 hours; The material is fed into an adiabatic furnace, filled with protective gas, and a high-energy laser beam generated by a carbon dioxide laser is used to scan the coating. After air cooling, a single-layer nano-aqueous coating is obtained. The laser wavelength is 10.2 μm, the scanning rate is 8 mm / s, the laser power is 200 W, and the overlap rate is 3%.

[0032] S3.2. Take out the inner liner coated with nano-water-based coating under high temperature, apply nano-organic ceramic coating to the inner liner by ultra-high speed laser cladding, and cure at high temperature to obtain a single layer of nano-organic ceramic coating. S3.3 Repeat steps S3, S3.1 and S3.2 according to the production grade of the inner liner until the corresponding thickness is achieved, and at least two layers of nano-water-based coating and nano-organic ceramic coating are alternately superimposed. The nano-water-based coating is applied to the contact side of the inner liner, and the outermost part of the non-contact side of the inner liner is always the nano-organic ceramic coating. Example

[0033] The protective coating for the inner liner of an electric air fryer includes a composite film structure formed by alternately applying nano-waterborne coatings and nano-organic ceramic coatings to create a nano-waterborne coating and a nano-organic ceramic coating.

[0034] The nano-waterborne coating is prepared by weight of 40 parts PDMS solution, 15 parts xylene, 18 parts silica sol, 10 parts silicon nitride, 10 parts FJ-14 powder, 12 parts nano titanium carbide, and 8 parts hydroxyl silicone oil. The PDMS solution has a molecular weight of 13400, a relative density of 0.97, and the molecular formula [Si(CH3)2-O-]n.

[0035] The nano-organic ceramic coating is prepared by weight of 5 parts cobalt sulfate, 30 parts nickel sulfate, 20 parts titanium boride, 20 parts silicon boride, 8 parts sodium molybdate, and 8 parts brightener. Among them, cobalt sulfate, nickel sulfate, titanium boride, silicon boride, and sodium molybdate are all pre-coarsely ground powders with a particle size of 150 μm, and the brightener is a food-grade silicone oil brightener.

[0036] The steps for applying a protective coating to the inner liner of an electric air fryer are as follows: S1. Prepare nano-waterborne coatings and nano-organic ceramic coatings according to the formula; Stir the PDMS solution and xylene in the prescribed amount thoroughly and then ultrasonically disperse for 20 minutes. Silicon nitride, FJ-14 powder, and nano-titanium carbide were sequentially added into the cavity of the supersonic particle bombardment and thoroughly crushed. After being removed, a mixed solution of PDMS and xylene was added and mixed. The supersonic particle bombardment was set with a gas pressure of 1.2 MPa, a jet velocity of 300 m / s, a bombardment angle of 57°, and a bombardment duration of 5 min. Silica sol and hydroxyl silicone oil are rapidly added during the mixing process, and the mixture is continuously stirred to obtain a nano-waterborne coating.

[0037] Add sufficient water to the prescribed amounts of titanium boride and silicon boride, and put them into a material mixer for preparation and mixing; the mixing speed is 600 r / min, and the mixing lasts for 20 minutes; Cobalt sulfate, nickel sulfate, sodium molybdate, and a brightener are added, followed by mixing of the blended materials. After washing with water, a nano-organic ceramic coating is obtained.

[0038] S2. After sanding the inner pot of the metal electric air fryer with sandpaper, ultrasonically clean it in petroleum ether for 15 minutes and dry it at room temperature. S3. Spray the nano-water-based coating and nano-organic ceramic coating onto the polished metal inner liner surface at a film thickness ratio of 2:1. S3.1 Apply nano-water-based coating and let stand at room temperature for 2 hours; The material is fed into an adiabatic furnace, filled with protective gas, and a high-energy laser beam generated by a carbon dioxide laser is used to scan the coating. After air cooling, a single-layer nano-aqueous coating is obtained. The laser wavelength is 10.5 μm, the scanning rate is 12 mm / s, the laser power is 200 W, and the overlap rate is 4%.

[0039] S3.2. Take out the inner liner coated with nano-water-based coating under high temperature, apply nano-organic ceramic coating to the inner liner by ultra-high speed laser cladding, and cure at high temperature to obtain a single layer of nano-organic ceramic coating. S3.3 Repeat steps S3, S3.1 and S3.2 according to the production grade of the inner liner until the corresponding thickness is achieved, and at least two layers of nano-water-based coating and nano-organic ceramic coating are alternately superimposed. The nano-water-based coating is applied to the contact side of the inner liner, and the outermost part of the non-contact side of the inner liner is always the nano-organic ceramic coating. Test case Following the steps and quantities of Example 1, two layers of nano-waterborne coating and nano-organic ceramic coating were alternately coated on the inner liner surface.

[0040] Comparative Example 1 Following the steps and dosage of Example 1, only two layers of nano-waterborne coating were applied to the inner liner surface.

[0041] Comparative Example 2 Following the steps and dosage of Example 1, only two layers of nano-organic ceramic coating were applied to the inner liner surface.

[0042] Comparative Example 3 Select an inner liner that already has a conventional ceramic coating.

[0043] The coating thickness of Experimental Example 1 and Comparative Examples 1-3 was kept consistent, i.e., the two coating thicknesses of Experimental Example 1 were halved. Comparative Example 3 was coated with a conventional ceramic coating to a predetermined thickness. Coating resistance tests were conducted on the four samples. The corrosion resistance of the inner liner was tested by ethanol immersion; the high-temperature and high-pressure resistance of the inner liner was tested by high-temperature and high-pressure vibration; and the grease resistance of the inner liner was tested by detecting surface grease residue after rinsing and settling. The results are shown in the table below. Ethanol soaking, 98% ethanol soaking for 300 hours 200℃, 35kPa, vibration amplitude 0.3mm, vibration motor 750r / min After rinsing and inverting for 10 minutes, the amount of residual grease... Experimental Example 1 No significant changes No significant changes 0.7% Comparative Example 1 No significant changes No significant changes 0.8% Comparative Example 2 No significant changes No significant changes 1% Comparative Example 3 The coating is easy to peel off Partial coating peeling 1.5% Since this mainly involves performance testing of ceramic coatings, Comparative Example 2 is excluded. Only Example 1, Comparative Example 2, and Comparative Example 3 are tested for surface hardness and impact resistance using the Vickers hardness test and drop weight test methods. The results are shown in the figure. Figure 3 As shown in the graph, it can be seen that Test Example 1 had the highest number of impacts and the highest surface hardness.

[0044] Based on the results of the two batches of experiments, it can be concluded that the composite protective coating structure obtained by the coating method and coating formulation of this application has superior performance in terms of corrosion resistance, high pressure resistance, high temperature resistance, grease resistance, surface hardness, and impact resistance.

[0045] It should be noted that this specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A protective coating for the inner liner of an electric air fryer, characterized in that: This includes alternating the application of nano-waterborne coatings and nano-organic ceramic coatings to form a composite film structure of nano-waterborne coating and nano-organic ceramic coating, with the non-contact side of the inner liner being an organic ceramic coating. The formulation of the nano-waterborne coating includes dimethylsiloxane PDMS solution, xylene, silica sol, silicon nitride, FJ-14 powder, nano titanium carbide, and hydroxyl silicone oil; The formulation of nano-organic ceramic coatings includes cobalt sulfate, nickel sulfate, titanium boride, silicon boride, sodium molybdate, and a brightener.

2. The protective coating and coating method for the inner liner of an electric air fryer according to claim 1, characterized in that: The nano-waterborne coating is prepared by weight of 30-40 parts PDMS solution, 10-15 parts xylene, 12-18 parts silica sol, 5-10 parts silicon nitride, 5-10 parts FJ-14 powder, 4-12 parts nano titanium carbide and 7-8 parts hydroxyl silicone oil.

3. The protective coating and coating method for the inner liner of an electric air fryer according to claim 2, characterized in that: The molecular weight of PDMS solution ranges from 780 to 13400, the relative density ranges from 0.92 to 0.97, and the molecular formula is [Si(CH3)2-O-]. n .

4. The protective coating and coating method for the inner liner of an electric air fryer according to claim 1, characterized in that: The nano-organic ceramic coating is prepared by weight of 3-5 parts cobalt sulfate, 15-30 parts nickel sulfate, 12-20 parts titanium boride, 12-20 parts silicon boride, 7-8 parts sodium molybdate and 5-8 parts brightener.

5. The protective coating and coating method for the inner liner of an electric air fryer according to claim 4, characterized in that: Cobalt sulfate, nickel sulfate, titanium boride, silicon boride, and sodium molybdate are all pre-ground powders with a particle size of 100-150 μm, and the brightener is a food-grade silicone oil brightener.

6. A method for applying a protective coating to the inner liner of an electric air fryer, characterized in that: The steps are as follows: S1. Prepare nano-waterborne coatings and nano-organic ceramic coatings according to the formulations described in any one of claims 1 to 5; S2. After sanding the inner pot of the metal electric air fryer with sandpaper, ultrasonically clean it in petroleum ether for 10-15 minutes and dry it at room temperature. S3. Spray the nano-water-based coating and nano-organic ceramic coating onto the polished metal inner liner surface at a film thickness of 1:1 to 2:

1. S3.1 Apply nano-water-based coating and let stand at room temperature for 1.5~2 hours; The coating is fed into an adiabatic furnace and filled with protective gas. A high-energy laser beam generated by a carbon dioxide laser is used to scan the coating. After air cooling, a single-layer nano-aqueous coating is obtained. S3.

2. Take out the inner liner coated with nano-water-based coating under high temperature, apply nano-organic ceramic coating to the inner liner by ultra-high speed laser cladding, and cure at high temperature to obtain a single layer of nano-organic ceramic coating. S3.3 Repeat steps S3, S3.1 and S3.2 according to the production grade of the inner liner until the corresponding thickness is achieved; S4. Inspect the integrity and gloss of the coating on the inner liner surface.

7. The method for applying the protective coating to the inner liner of an electric air fryer according to claim 6, characterized in that: In step S1, the prescribed amount of PDMS solution and xylene are thoroughly stirred and ultrasonically dispersed for 10-20 minutes; Silicon nitride, FJ-14 powder, and nano-titanium carbide were sequentially added into the cavity of the supersonic particle bombardment device and thoroughly crushed. After being removed, a mixed solution of PDMS and xylene was added and mixed. The supersonic particle bombardment is set with a gas pressure of 1~1.2MPa, a jet velocity of 270~300m / s, a bombardment angle of 57°, and a bombardment duration of 3~5min. Silica sol and hydroxyl silicone oil are rapidly added during the mixing process, and the mixture is continuously stirred to obtain a nano-waterborne coating.

8. The method for applying the protective coating to the inner liner of an electric air fryer according to claim 6, characterized in that: In step S1, the prescribed amounts of titanium boride and silicon boride are added to a sufficient amount of water and fed into a material mixer for preparation and mixing; the mixing speed is 500~600 r / min and the mixing lasts for 15~20 min. Cobalt sulfate, nickel sulfate, sodium molybdate, and a brightener are added, followed by mixing of the blended materials. After washing with water, a nano-organic ceramic coating is obtained.

9. The method for applying the protective coating to the inner liner of an electric air fryer according to claim 6, characterized in that: The laser wavelength in step S3.1 is 10.2~10.5μm, the scanning rate is 8~12mm / s, the laser power is 200w, and the overlap rate is 3~4%.

10. The method for applying the protective coating to the inner liner of an electric air fryer according to claim 6, characterized in that: In step S3.3, at least two layers of nano-waterborne coating and nano-organic ceramic coating are alternately superimposed. The nano-waterborne coating is applied to the contact side of the inner liner, while the outermost layer of the non-contact side of the inner liner is always the nano-organic ceramic coating.

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