Non-stick pan and process for its preparation

Abstract

The present application relates to the field of non-stick pot, especially to a non-stick pot and its preparation process, comprising the following steps: forming a micron rough surface on the inner surface of the pot body, wherein the copper content in the pot body is 4-5wt%, the carbon content is less than 0.25wt%, and the balance is iron; under inert atmosphere, using corrosive liquid to corrode the micron rough surface to obtain a nano-porous structure; sequentially performing nitrogenization treatment and oxidation treatment on the surface of the nano-porous structure to obtain a non-stick pot. The present application first corrodes nano-sized holes by corrosive liquid before constructing the oxide film, so that nano-sized holes can be uniformly and effectively formed, ensuring the physical non-stick effect. Finally, the micron and nano micro rough film layers have the functions of oil storage and oil locking during actual cooking, thereby realizing the physical non-stick function.

Description

Technical Field

[0001] This invention relates to the field of non-stick cookware, and more particularly to a non-stick cookware and its manufacturing process. Background Technology

[0002] Currently, conventional non-stick pans require a chemical non-stick coating sprayed onto the inner surface. This chemical coating is prone to decomposition and failure at high temperatures, and it is quickly damaged by the use of metal spatulas. To achieve non-stick pans that are non-stick, easy to clean, and provide rapid and even heating, various solutions are available on the market. For example, CN201020591079.7 represents a solution where multiple grooves are created on the top surface of the pan's bottom to form a textured pattern, with a Teflon non-stick layer placed within these grooves. Another solution, CN201310455227.0, further refines the design of the groove texture, specifying the length, width, and height of the groove stripes, as well as the size and height of the raised dots. A non-stick coating is then sprayed onto this base, and the final product is achieved through further processes such as polishing the pan's surface.

[0003] While the solutions mentioned above achieve a non-stick effect to some extent, they all share the same problem: they use chemical non-stick coatings. As is well known, the chemical non-stick coating on non-stick pans is prone to losing its non-stick properties or peeling off easily when cooking at high temperatures, leading to food sticking to the pan and the risk of accidentally ingesting the chemical coating.

[0004] To address the aforementioned issues, a prior Chinese invention patent with publication number "CN111493648B" discloses a physically non-stick pan and its preparation method. The pan includes a body, the inner surface of which is made of iron or stainless steel and has a physically non-stick layer. This layer comprises a rough surface at least on the micrometer scale, further forming a nano-scale rough porous oxide film on the rough surface. The pore size of the oxide film can expand or contract with changes in heating temperature. The surface structure mimics that of a lotus leaf, taking into account the environment in which the non-stick pan is located, achieving a physically non-stick effect by combining the oxide film on the rough surface.

[0005] The above-mentioned method involves oxidizing the pot body after it has reached the hardening standard, further forming a nano-scale rough porous oxide film on the rough surface of the pot body. The nano-scale roughness of the oxide film is mainly generated by oxide particles produced during the oxidation process. Examples include the oxide (iron oxide) of iron pots and the oxide film of stainless steel (mainly composed of chromium trioxide, etc.).

[0006] In actual production, it was found that the nanoscale roughness formed by oxide film is difficult to guarantee the formation of porous structures and needs further improvement. Summary of the Invention

[0007] To address the aforementioned problems, the primary objective of this invention is to provide a non-stick pan manufacturing process. This method involves first etching nanoscale pores using a corrosive liquid before constructing the oxide film. This uniformly and effectively forms nanoscale pores, ensuring a physically non-stick effect. Finally, the micron- and nano-scale rough film layer possesses oil-retaining and oil-locking properties during actual cooking, thereby achieving the physically non-stick function.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A non-stick pan manufacturing process includes the following steps:

[0010] A micron-level rough surface is formed on the inner surface of the pot body, wherein the copper content in the pot body is 4-5 wt%, the carbon content is less than 0.25 wt%, and the balance is iron;

[0011] Nanoporous structures are obtained by etching the micron-scale rough surface with a corrosive liquid under an inert atmosphere.

[0012] The surface of the nanoporous structure is subjected to nitriding and oxidation treatments in sequence to obtain a non-stick pan.

[0013] This invention employs the aforementioned technical solution, which relates to a non-stick pan manufacturing process. This process requires first forming a micron-level rough surface on the inner surface of the pan. The construction of the micron-level rough surface can be referenced from the steps disclosed in the prior Chinese invention patent with publication number "CN111493648B". Then, under an inert atmosphere, a corrosive liquid is used to etch the micron-level rough surface to obtain a nanoporous structure, ensuring that uniformly distributed nano-sized pores are formed on the pan surface. Finally, nitriding and oxidation treatments are performed to obtain the non-stick pan.

[0014] Compared to the prior patent solutions cited in the background art, this solution first uses a corrosive liquid to etch nanoscale pores before constructing the oxide film. This ensures the uniform and effective formation of nanoscale pores, guaranteeing a physical non-stick effect. Finally, the micron and nano-scale rough film layer has an oil-retaining and oil-locking function during actual cooking, thereby achieving the physical non-stick function.

[0015] The specific principle is as follows: when the user heats the pot, the pores of the oxide film expand, facilitating the entry of grease. When the heating of the pot is stopped, the pot temperature gradually cools down, the pores of the oxide film shrink, and the grease that has entered the pores is locked inside, thus achieving the oil-locking function.

[0016] Furthermore, before forming a micron-level roughness on the inner surface of the pot, the method further includes etching an uneven structure on the inner surface of the pot.

[0017] In the specific design, the diameter of the groove structure is 0.2 to 0.4 mm, the depth of the groove structure is 20 to 60 micrometers, and the center distance between adjacent grooves is 0.4 to 0.8 mm.

[0018] Preferably, the area of ​​the groove structure accounts for 10-25% of the inner surface of the pot body.

[0019] The uneven structure made on the inner surface of the pot can store and retain oil during cooking, and as described in the background technical solution, it can also form an air cushion layer inside the concave points, thereby improving the physical non-stick effect at a macro level.

[0020] In a further embodiment, obtaining a nanoporous structure by etching the micron-scale rough surface with a corrosive liquid under an inert atmosphere includes:

[0021] In an inert atmosphere, at a pressure of 0.05–0.1 MPa and a temperature of 400–580°C, a corrosive liquid is atomized or vaporized and applied to a micron-scale rough surface to corrode and obtain a nanoporous structure; and / or,

[0022] The corrosion depth is 1 to 3 micrometers extending perpendicularly from the inner surface of the pot towards the pot body.

[0023] Under the aforementioned conditions, this method atomizes or vaporizes the corrosive liquid and then applies it to a micron-level rough surface to corrode and obtain a nanoporous structure. Because the corrosive liquid is atomized or vaporized, the corrosive atomized liquid or gas is more evenly distributed during the processing and has stronger penetrability, thereby making the corrosion depth extend 1 to 3 microns perpendicular to the inner surface of the pot towards the pot body.

[0024] In the specific formulation, the corrosive liquid includes any one or more of the following: hydrochloric acid with a concentration of 30-40 wt%, nitric acid with a concentration of 10-15 wt%, and hydrofluoric acid with a concentration of 40-50 wt%. After being atomized by a stirring fan, the liquid is directed to the inner surface of the pot body and corroded at an environment of 400-580 degrees Celsius for 0.5-2 hours, creating micro- and nano-sized pores on the inner surface of the pot body with a corrosion depth of 1-3 micrometers.

[0025] Preferably, the nitriding treatment includes: introducing nitriding gas at 450-570°C, with a nitriding gas flow rate of 5-15 times the nitriding furnace volume per hour, and performing surface nitriding for 6-20 hours to form a nitrided layer.

[0026] Preferably, the oxidation treatment includes: introducing an oxidizing liquid at 450-550°C with a flow rate of 15-25 liters / hour, and oxidizing the inner surface of the pot body for 1-2 hours after atomization to form an oxide film on the infiltration layer.

[0027] Preferably, the pot body is made of low-carbon steel plate with a copper content of 4-5 wt% or low-carbon cold-rolled steel plate with a copper content of 4-5 wt%.

[0028] The second objective of this invention is to provide a non-stick pan, characterized in that it is prepared using the above-described non-stick pan preparation process. Detailed Implementation

[0029] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0030] This embodiment relates to a non-stick pan, which adopts the following non-stick pan manufacturing process, including the following steps:

[0031] Step 1: The pot body is made of low-carbon steel plate with a copper content of 4-5 wt% or low-carbon cold-rolled steel plate with a copper content of 4-5 wt%; wherein the copper content in the pot body is 4-5 wt%, the carbon content is less than 0.25 wt%, and the balance is iron.

[0032] Step 2: Etch an uneven structure on the inner surface of the pot body. In the uneven structure, the diameter of the groove is 0.2–0.4 mm, the depth is 20–60 micrometers, and the center-to-center distance between adjacent grooves is 0.4–0.8 mm; the area of ​​the groove structure occupies 10–25% of the inner surface of the pot body.

[0033] Step 3: Form a micron-level rough surface on the inner surface of the pot body. Specifically, select 46-80 mesh brown or white corundum abrasive, use 0.4-0.8 MPa compressed air as power, and use a high-speed jetting device to spray the abrasive onto the inner surface of the pot body, so that the surface of the pot body is formed by multiple protrusions at least at the micron level.

[0034] Step 4: The pot body is placed in a nitriding furnace. Under an inert atmosphere, a corrosive liquid is used to etch a nanoporous structure onto the micron-level rough surface. Specifically, the furnace environment is maintained at a pressure of 0.05–0.1 MPa and a temperature of 400–580°C. The corrosive liquid is atomized or vaporized and applied to the micron-level rough surface to etch the nanoporous structure. The etching depth is 1–3 microns perpendicular to the inner surface of the pot body and extending towards the pot body. In this method, under the above-mentioned conditions, the corrosive liquid is atomized or vaporized and then applied to the micron-level rough surface to etch the nanoporous structure. Because the corrosive liquid is atomized or vaporized, the corrosive atomized liquid or gas is more evenly distributed during the process and has stronger penetrability, thus making the etching depth 1–3 microns perpendicular to the inner surface of the pot body and extending towards the pot body. In the specific formulation, the corrosive liquid includes any one or more of the following: hydrochloric acid with a concentration of 30-40 wt%, nitric acid with a concentration of 10-15 wt%, and hydrofluoric acid with a concentration of 40-50 wt%. After being atomized by a stirring fan, the liquid is directed to the inner surface of the pot body and corroded at an environment of 400-580 degrees Celsius for 0.5-2 hours, creating micro- and nano-sized pores on the inner surface of the pot body with a corrosion depth of 1-3 micrometers.

[0035] Step 5: The surface of the nanoporous structure is subjected to nitriding treatment, which includes: passing nitriding gas at 450-570℃, with a nitriding gas flow rate of 5 to 15 times the nitriding furnace volume per hour, and performing surface nitriding for 6 to 20 hours to form a nitrided layer.

[0036] Step 6: The surface of the nanoporous structure is subjected to oxidation treatment, which includes: passing an oxidation liquid through at 450-550℃, with a flow rate of 15-25 liters / hour, and oxidizing the inner surface of the pot body for 1-2 hours after atomization, thereby forming an oxide film on the infiltration layer.

[0037] Step 7: Cool and remove from the oven to obtain a non-stick pan.

[0038] Based on the non-stick pan manufacturing process described above, experimental groups 1-9 and control groups 1-7 were set up. Each experimental and control group was tested according to the general egg-frying standard. The unit in the table is the average number of eggs fried. The test method is as follows: 50 non-stick pans were set up in each experimental group, and the number of eggs fried continuously in the non-stick pans without oil was measured, and the average number of eggs fried was calculated.

[0039]

[0040]

[0041]

[0042] The above experiments included experimental groups 1-9 and control groups 1-13. The following conclusions were drawn: 1. Control group 13 did not employ step 4 in its technical approach, i.e., it did not use corrosive liquid to etch the nanoporous structure. It can be seen that, compared with the other experimental and control groups, control group 13 had significantly fewer consecutively fried eggs in the oil-free state, and localized sticking occurred. This can be inferred to be due to the uneven and insufficient distribution of the nanoporous structure. In contrast, the experimental and control groups that added step 4 significantly increased the number of consecutively fried eggs in the oil-free state, demonstrating a positive effect.

[0043] 2. Comparing experimental groups 1-3 with control groups 1 and 2, it was found that when hydrochloric acid was used as the corrosive liquid, controlling the parameters to a concentration of 30-40 wt% and corrosion in an environment of 400-580 degrees Celsius for 0.5-2 hours resulted in significant effects. Compared with control groups 3-4, experimental group 1 required a suitable concentration of hydrochloric acid to obtain a product with a relatively appropriate number and uniform distribution of nanoporous structures. Furthermore, the inventors speculated that a suitable concentration of hydrochloric acid was necessary to obtain nanoporous structures of a specific depth, and that the combination of nanoporous structures of a specific depth with micron-level uneven and rough structures would result in a better non-stick effect.

[0044] 3. Comparing experimental groups 4-6 with control groups 5 and 6, it was found that when using nitric acid as the corrosive liquid, controlling the parameters to a concentration of 10-15 wt% and a corrosion effect of 0.5-2 hours in an environment of 400-580 degrees Celsius was significant. Compared with control groups 7-8, experimental group 4 showed that controlling the appropriate nitric acid concentration was necessary to obtain a product with a relatively suitable number and relatively uniform distribution of nanoporous structures. Furthermore, the inventors speculate that an appropriate nitric acid concentration is needed to corrode nanoporous structures to a specific depth, and that the combination of nanoporous structures at a specific depth with micron-level unevenness and roughness can achieve a better non-stick effect.

[0045] 4. Comparing experimental groups 7-9 with control groups 9 and 10, it was found that when hydrofluoric acid was used as the corrosive liquid, controlling the parameters to a concentration of 40-50 wt% and corrosion at 400-580 degrees Celsius for 0.5-2 hours yielded significant results. Compared to control groups 11-12, experimental group 7 demonstrated that controlling the appropriate hydrofluoric acid concentration was necessary to obtain a product with a relatively suitable number and uniform distribution of nanoporous structures. Furthermore, the inventors hypothesize that a suitable hydrofluoric acid concentration is required to corrode nanoporous structures to a specific depth, and that this specific depth of nanoporous structure, combined with a micron-level rough texture, results in a better non-stick effect.

[0046] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0047] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A non-stick pan manufacturing process, characterized in that: Includes the following steps: A micron-level rough surface is formed on the inner surface of the pot body, wherein the copper content in the pot body is 4~5wt%, the carbon content is less than 0.25wt%, and the balance is iron; Nanoporous structures are obtained by etching the micron-scale rough surface with a corrosive liquid under an inert atmosphere. The surface of the nanoporous structure is subjected to nitriding and oxidation treatments in sequence to obtain a non-stick pan; The method of obtaining a nanoporous structure by etching the micron-scale rough surface with a corrosive liquid under an inert atmosphere includes: Under an inert atmosphere, at a pressure of 0.05~0.1 MPa, and at a temperature of 400~580℃, a corrosive liquid is atomized or vaporized and applied to a micron-scale rough surface for corrosion for 0.5~2 hours to obtain a nanoporous structure; the corrosion depth is 1~3 microns perpendicular to the inner surface of the pot and extending towards the pot body. The corrosive liquid includes any one or more of the following: hydrochloric acid with a concentration of 30-40 wt%, nitric acid with a concentration of 10-15 wt%, and hydrofluoric acid with a concentration of 40-50 wt%.

2. The non-stick pan preparation process according to claim 1, characterized in that, Before forming a micron-level roughness on the inner surface of the pot, the method further includes etching an uneven structure on the inner surface of the pot.

3. The non-stick pan preparation process according to claim 2, characterized in that, In the concave-convex structure, the diameter of the groove structure is 0.2~0.4 mm, the depth of the groove structure is 20~60 micrometers, and the center distance between adjacent grooves is 0.4~0.8 mm.

4. The non-stick pan preparation process according to claim 2 or 3, characterized in that, The area of ​​the groove structure occupies 10-25% of the inner surface of the pot body.

5. The non-stick pan preparation process according to claim 1 or 2, characterized in that, The nitriding treatment includes: introducing nitriding gas at 450-570°C, with a nitriding gas flow rate of 5-15 times the nitriding furnace volume per hour, and performing surface nitriding for 6-20 hours to form a nitrided layer.

6. The non-stick pan preparation process according to claim 1 or 2, characterized in that, The oxidation treatment includes: introducing an oxidizing liquid at 450-550℃ with a flow rate of 15-25 liters / hour, and oxidizing the inner surface of the pot body for 1-2 hours after atomization to form an oxide film on the infiltration layer.

7. A non-stick pan, characterized in that, It is prepared using the non-stick pan preparation process described in any one of claims 1 to 6.

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