Metallic cooking utensil and method for manufacturing the same

Abstract

The present application relates to the technical field of kitchen utensils, in particular to a metal cooking utensil and a preparation method thereof. The present application provides a metal cooking utensil, which comprises a metal base layer, a nanoparticle layer and a hydrophobic material layer. The metal base layer has a concave-convex texture structure in the form of bionic leaf vein morphology, which comprises a plurality of convex rib units and recessed units formed between the convex rib units, and the vertical projection shapes of any two adjacent convex rib units on the surface of the metal base layer are different from each other; the nanoparticle layer is randomly shaped and covers the concave-convex texture surface; and the hydrophobic material layer covers the surface of the nanoparticle layer. The metal cooking utensil has the concave-convex texture structure in the form of bionic leaf vein morphology, and the synergistic effect of the nanoparticle layer and the hydrophobic material layer reduces linear wear through the irregularly distributed convex rib units, and the nano structure enhances the hydrophobicity, which has the advantages of improving the surface hydrophobicity to enhance the anti-sticking performance and prolonging the service life of the texture structure.

Description

Technical Field

[0001] This invention relates to the field of kitchen utensils technology, and in particular to a metal cooking utensil and its preparation method. Background Technology

[0002] In existing technologies, metal cooking utensils suffer from insufficient hydrophobicity due to the high surface energy of the metal material, which easily leads to problems such as food sticking (e.g., rice sticking to the pot, stir-frying vegetables burning) and discoloration at high temperatures. Existing solutions prevent sticking by processing the metal surface to form a matrix of uneven dots or textures.

[0003] However, the existing techniques for creating textured structures are limited to the micrometer level due to process constraints, resulting in limited improvement in surface hydrophobicity and thus less than ideal non-stick performance. Furthermore, these matrix-distributed textured structures typically exhibit a distinct directional arrangement. In practical use, the strength of this textured structure is relatively low, especially when repeatedly rubbed with utensils (such as spatulas), easily producing linear scratches. With increased use, the textured structure gradually deteriorates, causing a significant decrease in its non-stick performance in the short term, making it difficult to meet the needs of non-stick cookware. Summary of the Invention

[0004] The main objective of this invention is to provide a metal cooking utensil and its preparation method, which aims to improve the problem of insufficient non-stick durability of existing pots and pans with textured surfaces.

[0005] To achieve the above objectives, an embodiment of the present invention provides a metal cooking utensil, comprising:

[0006] The metal substrate layer is provided with a textured structure in the shape of a biomimetic leaf vein. The textured structure includes a number of raised rib units and recessed units formed between the raised rib units. The planar projection shapes of any two adjacent raised rib units in the vertical direction on the surface of the metal substrate layer are different.

[0007] A nanoparticle layer conformally covers the surface of the textured structure.

[0008] A hydrophobic material layer is conformally coated on the surface of the nanoparticle layer.

[0009] In some embodiments, the depth of the recessed unit does not exceed one-quarter of the thickness of the metal substrate layer; and / or, the depth of the recessed unit ranges from 10 μm to 100 μm.

[0010] In some embodiments, the nanoparticle layer comprises nanoparticles, the nanoparticles being made of at least one of elemental silicon, silicon oxide, silicon nitride, tungsten nitride, and zirconium nitride, and the nanoparticles having a particle size range of 50 nm to 1000 nm.

[0011] In some embodiments, the nanoparticles cover 20%-90% of the projected area of ​​the textured surface along the vertical direction.

[0012] In some embodiments, the thickness of the nanoparticle layer ranges from 0.05 μm to 2 μm; and / or, the thickness of the hydrophobic material layer ranges from 0.05 μm to 5 μm.

[0013] In some embodiments, the material of the hydrophobic layer includes at least one of silicone polymers, fluoropolymers, and ceramics.

[0014] In some embodiments, the metal substrate layer is made of at least one of iron, stainless steel, aluminum, copper, and titanium; and / or, the metal substrate layer comprises a multilayer structure.

[0015] In some embodiments, the textured structure includes a microstructure distributed on the surface of the metal substrate layer; the nanoparticle layer covers at least a portion of the microstructure to form a micro / nanostructure; wherein the hydrophobic material layer and the micro / nanostructure include polar covalent bonds.

[0016] On the other hand, embodiments of this application also provide a method for preparing a metal cooking utensil, comprising the following steps:

[0017] A textured structure resembling leaf veins is formed on the surface of a metal substrate through one of the following processes: embossing, etching, laser processing, or roughening.

[0018] A nanoparticle layer is deposited on the surface of the textured structure.

[0019] A hydrophobic material layer is formed on the surface of the nanoparticle layer by deposition through one of the following methods: spraying, dip coating, or evaporation deposition.

[0020] In some embodiments, in the step of depositing a nanoparticle layer on the surface of the textured structure, the deposition conditions include: vacuum degree 0.01Pa-0.2Pa, substrate bias voltage 150V-600V; target current 70-90A, and temperature 100-200℃.

[0021] In summary, the metal cooking utensil provided in this application features an irregular, textured structure resembling biomimetic leaf veins on the inner surface of the metal substrate layer. Combined with the synergistic effect of the nanoparticle layer and the hydrophobic material layer, the irregularly distributed raised rib units reduce linear wear. Here, "irregularly distributed" means that the planar projection shapes of any two adjacent raised rib units in the vertical direction on the surface of the metal substrate layer are different. Simultaneously, the nanostructure of the nanoparticle layer and the textured surface of the nanoparticle layer combine to form a micro / nano structure to enhance hydrophobicity. This provides the advantages of improved surface hydrophobicity to enhance non-stick properties and extend the service life of the textured structure. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the hierarchical structure of metal cooking utensils according to some embodiments of this application;

[0024] Figure 2 This is a partial schematic diagram of the surface of the raised and recessed texture structure of some embodiments of this application;

[0025] Figure 3 This is a partial cross-sectional schematic diagram of the raised and recessed texture structure of some embodiments of this application;

[0026] 10 - Metal substrate layer; 20 - Nanoparticle layer; 30 - Hydrophobic material layer. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0029] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0030] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0031] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0032] In the development of non-stick cooking utensils, coating technology and metal material innovation are the two main paths. In recent years, the use of pure metal materials such as stainless steel and titanium alloys to manufacture "zero-coating" cookware has become a trend, as it is welcomed by the market due to its advantages such as health, durability, corrosion resistance, and no risk of chemical coating peeling. However, the inherent high surface energy of metal materials results in poor hydrophobicity, which can easily cause food to stick during cooking (such as rice sticking to the pot and stir-frying vegetables burning) and discoloration at high temperatures.

[0033] To improve the non-stick properties of pure metal cookware, the current mainstream approach is to create a matrix-distributed lattice or textured structure on the surface of the cookware through mechanical stamping, etching, or laser processing. This structure aims to use the recesses to trap water or oil, forming a protective layer that supports food and reduces its contact area with the metal substrate, thus achieving a certain degree of non-stick performance. However, this type of structure has a directional arrangement, making it prone to linear scratches under mechanical friction. This leads to rapid wear and tear of the texture, and the non-stick performance decreases significantly with repeated use.

[0034] Based on this, this application proposes a metal cooking utensil, such as Figure 1 As shown, it comprises a metal substrate layer, a nanoparticle layer, and a hydrophobic material layer. The metal substrate layer is provided with a textured structure resembling biomimetic leaf veins. The textured structure includes several raised rib units and recessed units formed between the raised rib units. The planar projection shapes of any two adjacent raised rib units in the vertical direction on the surface of the metal substrate layer are different from each other. The nanoparticle layer conformally covers the surface of the textured structure. The hydrophobic material layer covers the surface of the nanoparticle layer.

[0035] like Figure 2 As shown, the biomimetic leaf vein-like textured structure refers to a three-dimensional structure that simulates the branching morphology of plant leaf veins. This can be achieved through embossing or laser processing. The phrase "the planar projection shapes of any two adjacent rib units are different in the vertical direction" means that when viewed from a direction perpendicular to the cookware surface, the contours of any two adjacent rib units on the two-dimensional plane are not repeated. Here, the vertical direction refers to the direction of the normal along any point on the cookware surface. In three-dimensional geometry, the normal is a straight line tangent to a given curve or surface and perpendicular to the tangent. For example, rib A may present a branching tree-like contour; its adjacent rib B may have an earthworm-like contour; and its adjacent rib C may have an irregular polygonal island-like contour. Thus, the shape and spatial arrangement of the rib units exhibit an irregular three-dimensional distribution. This arrangement breaks the regularity of existing traditional matrix textures (such as dot matrix, parallel stripes, or other regular intervals and sizes), forming a disordered network structure similar to plant leaf veins, which can effectively disperse the mechanical stress on the cookware surface. This "bionic leaf vein morphology texture structure" means that it imitates the vein network of plant leaves. It not only imitates the two-dimensional pattern of leaf veins, but more importantly, it imitates the three-dimensional undulating structure formed by the influence of leaf veins on the mesophyll tissue in three-dimensional space. The raised parts correspond to the leaf veins (as a supporting framework), and the concave parts correspond to the mesophyll area between the leaf veins. The final result is a three-dimensional microstructure surface structure with a specific spatial distribution pattern (such as dendritic, network, or hierarchical distribution).

[0036] Specifically, in the biomimetic leaf vein-shaped concave-convex texture structure, the concave units formed between the convex rib units include multiple interconnected grooves, which extend along irregular paths and have a bifurcated structure; wherein, the planar projection shapes of any two adjacent convex rib units in the vertical direction are different from each other, and there are interconnected bifurcated grooves between adjacent convex rib units, so that water vapor channels are formed on the inner surface of the grooves on the surface of the cookware.

[0037] In some embodiments, such as when the inner pot of a cooking appliance is used for cooking rice, the water vapor generated by the boiling inside the pot will accumulate in the upper area and, under external cooling conditions, will condense into water and flow downwards along the side wall of the pot. However, the surface of the inner pot, which is usually smooth or has an independent groove texture, will be blocked by the expanding rice, and the water cannot flow evenly along the inner wall to the fully heated bottom. This often results in the rice at the bottom being dry and hard, while the rice on the upper side and surface is soft and mushy, affecting the taste of the rice.

[0038] In this embodiment, irregularly distributed bifurcated grooves form interconnected steam channels, dividing the cookware surface into adjacent, differently shaped rib units. These interconnected steam channels establish multi-directional steam transport paths on the inner surface of the cookware, effectively guiding steam flow during cooking while reducing the possibility of blockages, thus improving heating uniformity and moisture distribution.

[0039] The irregular path extension refers to the groove orientation mimicking the natural diffusion trajectory of liquid, resulting in an irregular distribution of the ribbed units resembling the branching pattern of plant leaf veins. The water vapor channels formed by the grooves create a capillary effect, guiding condensate from the top to the bottom of the pot. The branching structure allows water flow to choose alternative paths when encountering local resistance, avoiding flow interruption caused by blockage of a single groove. The curved edges of the ribbed units reduce linear contact with the rice, lowering the probability of sticking. When water vapor condenses on the sidewalls, the irregular groove network provides multi-directional flow options, automatically adjusting the water flow distribution according to temperature differences to achieve a dynamic balance in moisture supply to the bottom and sides.

[0040] Compared to existing technologies, traditional solutions use independent straight grooves or smooth surfaces, resulting in a single water flow path that is easily blocked. In this embodiment, the grooves form a biomimetic water vapor interconnection network, establishing redundant flow paths. Their branching structure enhances the moisture regulation capability between areas, and combined with differently shaped rib units, they increase the heating area while reducing surface adhesion, achieving a more efficient dynamic moisture balance. This improves the non-stick performance and wear resistance of the cookware's inner surface.

[0041] Furthermore, the depth of the groove increases gradually along the side area, the arc transition area, and the bottom area of ​​the inner surface of the pot, and / or the width of the groove decreases gradually along the side area, the arc transition area, and the bottom area of ​​the inner surface, to guide the water flow on the inner surface of the pot in a dispersed manner. Preferably, the depth of the groove ranges from 10μm to 100μm, and the width of the groove ranges from 0.01mm to 4mm. The size of the groove is set according to the shape of the pot and should meet the following conditions: the average depth of the groove in the side area ≤ the average depth of the groove in the arc transition area ≤ the average depth of the groove in the bottom area, or the average width of the groove in the side area ≥ the average width of the groove in the arc transition area ≥ the average width of the groove in the bottom area.

[0042] The depth of the groove refers to the vertical distance between the bottom of the groove and the inner surface of the inner pot. The average depth of the groove is the arithmetic mean of measurements taken at different locations along the length of the groove. The side area refers to the entire vertical or near-vertical cylindrical wall surface of the inner pot, from the bottom to the opening. It can be formed into a continuous curved surface using a stamping process; its shallow groove structure helps control water flow speed and prevents excessive evaporation. The arc transition area refers to the transition surface connecting the side and bottom. A gradual curvature can be formed using a spinning process; a medium-depth groove maintains water flow continuity. The bottom area refers to the flat or spherical area at the bottom of the inner pot that directly contacts the heating element. The deepest groove is formed using laser etching to collect and store condensate flowing there. The gradient increasing distribution indicates that the groove depth exhibits a non-uniform spatial variation; depth differences can be achieved through segmented processing or parametric molds.

[0043] When condensation forms on the surface of the inner pot, the shallower grooves on the sides preferentially guide the water flow to form a thin liquid film, which then flows downwards under gravity. As the water flows through the arc-shaped transition area, the medium-depth grooves maintain flow continuity through capillary action, preventing the liquid film from breaking. Upon reaching the bottom area, the deepest grooves form a water storage space, allowing the water to evaporate fully in the high-temperature zone. This depth gradient avoids insufficient water retention time in the side areas due to excessively deep grooves, while also preventing flow resistance in the bottom area due to excessively shallow grooves, thus achieving an orderly migration of water from the top to the heating zone. This design establishes a depth gradient relationship, matching the groove structure to the thermodynamic conditions of each area, forming a water vapor channel that conforms to the laws of fluid dynamics.

[0044] Specifically, the average depth h1 of the grooves in the side area refers to the average depth of the grooves in the side area of ​​the inner pot. This can be achieved through laser engraving or chemical etching processes, used to form an initial condensation collection path on the side wall, while avoiding excessive depth that could cause rice to stick together or reduce structural strength. The average depth h2 of the grooves in the arc transition area refers to the average depth of the grooves in the transition area between the inner pot's side wall and bottom. This can be achieved using gradient processing parameters, used to enhance the water flow guidance ability in the curved area and prevent water vapor retention. The average depth h3 of the grooves in the bottom area refers to the average depth of the grooves in the bottom area of ​​the inner pot. This can be achieved through zoned control of processing depth, used to accelerate the transport of moisture to the high-temperature area, while limiting the ratio of h3 to h1 to no more than 1.5 times to prevent excessive depth differences from causing capillary imbalance.

[0045] A gradient distribution of groove depth is used to establish a continuous flow path from the sidewall to the bottom of the pot. The shallower grooves in the side areas allow condensate to initially collect on the sidewall without affecting the moisture content of the rice. The transition depth in the arc-shaped transition area accelerates the water flow in the curved area, while the greater depth in the bottom area promotes contact between moisture and the high-temperature area. The depth ratio of each area is strictly controlled to both facilitate the increasing gradient of capillary force and avoid water flow turbulence or structural weakness caused by abrupt changes in local depth.

[0046] This solution achieves dynamic balance of water flow through regionalized depth gradients and upper limit constraints, enabling precise control of water diversion capacity in different areas of the inner pot. This further reduces the difference in moisture content between the bottom and sidewall areas of the rice, resulting in a more uniform texture. Simultaneously, the limited depth ratio avoids problems such as turbulent flow or reduced structural strength caused by excessive local depth, thus improving the long-term reliability of the inner pot.

[0047] In this embodiment, the width of the groove is defined as follows: when fluid flows in a complex-shaped channel, a certain channel region is equivalent to a circular pipe in terms of flow characteristics, and the diameter of this assumed circular pipe is the width of the groove. A gradient decreasing width distribution of the groove means that the groove width gradually decreases as it extends from the side region to the bottom region. This can be achieved by designing a stepped width for the groove during mold processing or by adjusting the tool path segment by segment using CNC engraving technology. This distribution adapts to differences in fluid flow characteristics by adjusting the width ratio of different regions.

[0048] Specifically, the groove width in the bottom area is set to a minimum, the groove width in the arc transition area is slightly larger than that in the bottom area, and the groove width in the side area is the largest, forming a flow acceleration zone. During the flow of condensate, the width gradient leads to differences in fluid pressure distribution, driving the water flow from the side area to the bottom area. The decreasing width distribution of the grooves further enhances fluid mixing through turbulence, avoiding local stagnation, while optimizing the flow path to reduce resistance. Therefore, by setting a gradient change in the water vapor channels (depth and / or width of the grooves) on the inner surface of the cookware, better water vapor flow is achieved, further improving the non-stick performance. The biomimetic texture of the metal substrate layer, together with the nanoparticle layer and the hydrophobic material layer, achieves a durable non-stick effect.

[0049] The nanoparticle layer refers to a nanoscale particle coating layer formed by physical or chemical vapor deposition. It can be prepared using silicon-based or nitride materials, and its rough surface can enhance the adhesion of hydrophobic materials. The hydrophobic material layer refers to a polymer coating with low surface energy properties, which is formed as a continuous coating layer by chemical vapor deposition, effectively reducing surface wettability.

[0050] Specifically, the biomimetic texture of the metal substrate layer forms a multi-directional support structure through irregular rib units. When subjected to external forces, the irregular ribs disperse stress and prevent directional scratches. The recessed units and rib units form liquid storage spaces, storing oil films and forming an isolation layer during cooking. The nanoparticle layer forms nanoscale protrusions on the basis of micron-level texture, increasing the specific surface area and making the hydrophobic material bond more firmly. The hydrophobic material layer reduces surface energy, allowing the liquid to form a high contact angle and roll off quickly. The three elements work together to form a multi-level composite structure with macroscopic support, microscopic liquid storage, and nanoscale roughness.

[0051] Compared to existing technologies, the regularly arranged micron-scale lattice structure of current solutions is prone to scratches along the arrangement direction under friction, leading to damage to the texture integrity. The irregular vein texture of this solution has no fixed directionality; external forces are dispersed and absorbed by the irregular veins, significantly improving scratch resistance. The composite coating of nanoparticles and hydrophobic materials further reduces surface energy on the basis of the micron-structure, forming a more stable superhydrophobic interface.

[0052] Through the above technical solution, this application reduces the wettability of the metal surface, allowing the oil film to stably cover the textured liquid storage space, significantly reducing direct contact between food and the metal substrate. The irregularly distributed rib structure resists linear damage caused by utensil friction through multi-directional support, extending the service life of the textured structure. The synergistic effect of the nanoscale rough surface and the low surface energy coating achieves a durable anti-stick effect.

[0053] In some embodiments, the depth of the recessed units on the inner surface of the metal substrate layer does not exceed one-quarter of the thickness of the metal substrate layer.

[0054] Among them, such as Figure 3 As shown, the depth of a recessed unit refers to the vertical distance from the top to the bottom of the recessed portion in the textured structure. This depth can be controlled through etching or embossing processes to achieve the desired penetration. This parameter is directly related to the mechanical integrity of the metal substrate; shallower recesses can prevent stress concentration that could weaken the substrate structure.

[0055] The thickness of the metal substrate layer refers to the remaining material thickness of the substrate in the area where the recessed unit is located. It can be achieved by selecting the initial sheet thickness in combination with the surface machining allowance. By limiting the ratio between the recess depth and the substrate thickness, the metal substrate can still have sufficient resistance to deformation after processing.

[0056] Specifically, the depth of the recessed units is constrained by the thickness of the metal substrate layer. By controlling the recess depth within one-quarter of the substrate thickness, the metal substrate retains sufficient mechanical strength after texturing. During cooking, when the metal substrate is subjected to external mechanical friction or thermal stress, the shallower recessed units do not significantly weaken the substrate structure, thus preventing the textured structure from failing due to substrate deformation or damage. Simultaneously, the depth maintained by the recessed units still creates liquid storage spaces, maintaining the continuity of the oil or water film through capillary action, achieving dynamic isolation between the food and the metal surface.

[0057] If the depth of the depression often exceeds one-third of the substrate thickness, it results in excessively thin material in localized areas of the substrate. During repeated rubbing with a spatula, cracks easily propagate from the edges of these deep depressions, eventually leading to the overall peeling off of the texture. This solution establishes a correlation control mechanism between depth and substrate thickness, further improving the damage resistance of the textured structure while preserving its liquid storage function.

[0058] Through the above technical solution, this application further solves the problem of decreased mechanical strength caused by excessively deep recesses in the surface texture of the metal substrate, and avoids texture failure caused by cracking in weak areas of the substrate. At the same time, reasonable control of the recess depth ensures that the liquid storage space remains stable under high-temperature cooking conditions, extending the duration of the non-stick effect.

[0059] In some embodiments, the depth of the recessed unit ranges from 10 μm to 100 μm. Too shallow a recess will result in insufficient liquid storage, making it difficult to form a good insulating layer; too deep a recess will weaken the structural strength of the metal substrate. Specifically, when the depth is controlled within the range of 10 to 100 micrometers, the recessed unit can both form an insulating layer by storing liquid to reduce contact between the food and the metal substrate, and avoid localized stress concentration or a decrease in overall mechanical strength of the metal substrate due to excessive depth.

[0060] In some alternative embodiments, the depth of the recessed unit ranges from 30 μm to 60 μm. When the depth range is controlled between 30 μm and 60 μm, the recessed unit can further stabilize and store oil or water films during cooking, while the metal substrate can maintain its structural integrity when subjected to spatula friction or high-temperature thermal stress, further preventing scratches from spreading or texture from collapsing.

[0061] Compared to existing technologies, the recessed units in existing technologies typically employ a uniformly distributed micron-sized pit structure, with the depth set solely based on anti-sticking requirements without considering the compatibility with the mechanical properties of the metal substrate. This results in the pits being easily scratched or crushed during actual use. In contrast, this solution, by limiting the depth range, achieves a synergistic optimization between the liquid storage function and structural strength of the recessed unit.

[0062] Through the above technical solution, this application achieves stable maintenance of the liquid isolation layer during cooking, while avoiding the problem of reduced substrate strength caused by excessively deep depressions, so that the metal substrate can further maintain the integrity of the texture structure and the durability of the non-stick performance under repeated friction and high temperature environments.

[0063] In some embodiments, the nanoparticle layer comprises nanoparticles, the nanoparticles being made of at least one of elemental silicon, silicon oxide, silicon nitride, tungsten nitride, and zirconium nitride, and the nanoparticles having a particle size range of 50 nm to 1000 nm.

[0064] The nanoparticle layer refers to a composite structural layer formed on the surface of a metal substrate through physical or chemical deposition processes. Specifically, it can be achieved using magnetron sputtering or plasma-enhanced chemical vapor deposition (PECVD). Its function is to construct a composite interface between micron-level uneven structures and nanon-level roughness. Elemental silicon and silicon oxide possess high hardness, which can increase surface mechanical strength to resist scratch damage; for example, amorphous silicon particles can be deposited using radio frequency magnetron sputtering. Tungsten nitride and zirconium nitride possess high chemical inertness and can be synthesized using reactive magnetron sputtering in a nitrogen atmosphere. Their function is to inhibit oxidation and corrosion under high-temperature cooking conditions. The particle size range of 50nm-1000nm can synergistically interact with the micron-level uneven structure of the substrate. This can be achieved by adjusting the target power and gas flow rate during the deposition process. Its function is to balance the dispersion and packing density of the nanoparticles, avoiding agglomeration due to excessively small particle size or structural collapse due to excessively large particle size.

[0065] Specifically, by controlling the material composition and particle size distribution of nanoparticles, a uniformly covering nanoscale rough layer is formed on a micron-scale textured surface. Elemental silicon or silicon nitride particles form anchoring nodes on the substrate surface, enhancing the adhesion of subsequent hydrophobic material layers through mechanical interlocking effects. Particles with a diameter in the range of 50nm-1000nm form submicron-scale secondary protrusions, which, in conjunction with the micron-scale recessed units of the substrate, construct a multi-level composite structure, increasing the interfacial energy barrier at the solid-liquid interface. Tungsten nitride particles, through their high hardness, improve the surface wear resistance and preferentially withstand shear stress during spatula friction, thereby protecting the substrate texture structure from damage.

[0066] In some embodiments, the particle size of the nanoparticles ranges from 100 nm to 500 nm. This further facilitates the formation of micro-nano rough surfaces and enhances hydrophobicity.

[0067] Compared to existing technologies, traditional methods rely solely on single-scale micron-level uneven structures, resulting in insufficient surface roughness to form a stable gas-liquid interface and limited mechanical strength, making them prone to linear scratches. This solution introduces a nanoparticle layer to construct a micro / nano composite structure, maintaining the function of the liquid-retaining groove while enhancing surface hydrophobicity through nanoscale secondary roughness. The hard nanoparticles act as a physical barrier to disperse external loads, further blocking the continuous propagation path of scratches on the substrate.

[0068] Through the above technical solution, this application can significantly improve the surface hydrophobicity without damaging the micron-level liquid storage structure, reducing the direct contact area between food and the metal substrate during cooking. The nanoparticle layer, as a transition layer, enhances the interfacial bonding strength and reduces the risk of peeling of hydrophobic materials due to differences in thermal expansion coefficients. The introduction of hard particles gives the surface resistance to plastic deformation, maintaining the integrity of the multi-level rough structure even after long-term use, thereby extending the duration of the non-stick performance.

[0069] In some embodiments, the projected area coverage of nanoparticles on the surface of the textured structure along the vertical direction is 20%-90%.

[0070] The projected area coverage refers to the proportion of the area covered by nanoparticles per unit area. This can be controlled using magnetron sputtering or vapor deposition processes by adjusting parameters such as deposition time, target power, or substrate bias. This feature, by controlling the distribution density of nanoparticles, achieves both the filling effect of gaps in micron-scale uneven structures and avoids excessive deposition leading to particle stacking.

[0071] Specifically, the coverage ratio of nanoparticles on the textured surface is limited to a specific range. When the coverage is insufficient, the nanoparticles cannot effectively fill the gaps formed by the micron-sized structures, resulting in insufficient reduction of surface energy. When the coverage is too high, particle accumulation will block the liquid storage function of the micron-sized recessed units and weaken the anti-friction performance of the matrix structure. By controlling the coverage rate between 20% and 90%, the nanoparticles can both form local hydrophobic regions and retain the liquid storage space of the recessed units.

[0072] In some embodiments, the projected area coverage of the nanoparticles on the textured surface is 50%-80%.

[0073] The preferred coverage range of 50%-80% refers to the uniform distribution of nanoparticles on the surface of the uneven structure through optimized process parameters, which can be achieved by segmented deposition or dynamic scanning deposition. This range can balance hydrophobicity and structural stability, improving the synergistic effect between the nanoparticle layer and the micron structure while maintaining the mechanical support properties of the matrix texture.

[0074] When the particle density is preferably between 50% and 80%, a critical state is reached, which allows for the formation of a continuous hydrophobic layer on the surface of the micron-level ribbed units, while avoiding complete closure of the recessed units. This range has been experimentally verified to maintain the bonding strength between the particle layer and the matrix during dynamic friction.

[0075] If the nanoparticle coating method for metal cooking utensils typically involves uniform deposition across the entire surface, resulting in a near 100% coverage, it may over-cover the micron-level uneven texture, causing it to lose its liquid retention function. This solution, however, limits the coverage range, preserving the liquid retention capacity of the micron-structure while leveraging the hydrophobic properties of the nanoparticles to reduce surface energy, forming a dual anti-stick mechanism. No existing technology discloses any method for achieving synergistic effects between micro and nanostructures through coverage control.

[0076] Through the above technical solution, this application solves the problems of fluctuations in hydrophobic properties and decreased structural strength caused by insufficient or excessive nanoparticle coverage. During cooking, the synergistic effect of the nanoparticle layer and the micron-level recessed liquid storage structure can form a stable gas-liquid isolation layer, reducing direct contact between food and the metal substrate; at the same time, the appropriate coverage of nanoparticles avoids interlayer stress caused by excessive deposition, further improving the substrate texture from being easily damaged by friction.

[0077] In some embodiments, the thickness of the nanoparticle layer ranges from 0.05 μm to 2 μm.

[0078] The role of the nanoparticle layer is to increase surface roughness and provide an adhesion substrate for hydrophobic materials. The thickness range refers to the size of the nanoparticle layer in the direction perpendicular to the substrate surface, which can be controlled by adjusting the deposition time or process parameters. The selection of this range can balance coverage continuity and structural stability.

[0079] When the nanoparticle layer is within the aforementioned thickness range, a uniform and continuous surface coverage can be formed, avoiding localized exposure due to excessive thinness or stress concentration caused by excessive thickness. When cooking utensils experience temperature changes or mechanical friction, the particle layer at this thickness can better buffer external forces, preventing interlayer delamination due to insufficient bonding between particles. Simultaneously, this thickness range provides a more suitable three-dimensional roughness to the surface, offering better support for the subsequent construction of the hydrophobic material layer's microstructure.

[0080] This solution, by limiting a specific thickness range, ensures that the particle layer maintains interfacial bonding stability even under differences in thermal expansion coefficients at high temperatures, overcoming the problem of low wear resistance caused by inappropriate thickness in traditional structures. Through the above technical solution, this application achieves reliable bonding between the nanoparticle layer and the substrate structure under high-temperature cooking environments, further preventing surface defects caused by particle detachment, while maintaining a stable surface roughness state, providing structural protection for the long-term maintenance of hydrophobic properties.

[0081] In some embodiments, the thickness of the hydrophobic material layer ranges from 0.05 μm to 5 μm.

[0082] The thickness of the hydrophobic material layer refers to the vertical dimension of the organic or inorganic material covering the surface of the nanoparticle layer. This thickness can be achieved using plasma-enhanced chemical vapor deposition, spraying, or spin coating processes. This thickness range ensures hydrophobic properties while avoiding internal stress concentration caused by material accumulation. The continuous coverage of the hydrophobic material layer refers to the complete microscopic coverage of the undulating structure of the nanoparticle layer surface. This can be achieved by adjusting the deposition rate or solution concentration to avoid localized uncovering that could lead to increased surface energy.

[0083] Setting the thickness of the hydrophobic material layer to be greater than 0.05 μm helps to cover the surface protrusions of the nanoparticle layer, thereby forming a continuous interface layer with low surface energy. When the thickness is controlled within 5 μm, it helps to alleviate the interfacial cracking problem caused by the difference in the thermal expansion coefficients between layers. If the hydrophobic layer is too thick, cracks may appear under high-temperature thermal shock conditions; while if the coating is too thin, it is difficult to fully cover the microstructure of the substrate, thus affecting the stability of the hydrophobic properties. By limiting the thickness range of the hydrophobic material layer, a balance can be achieved between adapting to the three-dimensional morphology of the substrate and mechanical strength and interfacial stress distribution.

[0084] In some embodiments, the thickness of the hydrophobic material layer ranges from 0.5 μm to 2 μm. By further limiting the thickness of the hydrophobic material layer, the balance between the mechanical strength of the hydrophobic material layer and the interfacial stress distribution is further improved.

[0085] Through the above technical solution, this application can form a stable low surface energy interface, reducing direct contact between food and metal substrate during cooking. The hydrophobic material layer of this thickness can withstand repeated scratching, preventing a decrease in non-stick performance due to mechanical damage, while also preventing coating peeling caused by thermal cycling, further extending the service life of the cooking appliance.

[0086] In some embodiments, the material of the hydrophobic layer includes at least one of silicone polymers, fluoropolymers, and ceramics.

[0087] Organosilicon polymers refer to high molecular weight compounds containing silicon-oxygen bonds in their main chain. Specifically, they can be achieved using polydimethylsiloxane or silicone rubber. Through the flexibility of their molecular chains and low surface energy, they form a continuous coating film on the surface of nanoparticle layers. Fluoropolymers are synthetic polymers containing fluorine atoms in their main chain or side chains. Specifically, they can be achieved using polytetrafluoroethylene or fluorinated ethylene-propylene copolymers. The strong electronegativity of fluorine atoms reduces the surface energy of the material. Ceramics are inorganic non-metallic materials formed through high-temperature sintering. Specifically, they can be achieved using alumina or silicon carbide ceramic coatings. High hardness and thermal stability enhance the surface's resistance to mechanical friction.

[0088] Organosilicon polymers, through the flexibility of their molecular chains, form a uniform coating on the surface of nanoparticles, reducing the generation of surface microcracks; fluoropolymers, through the directional arrangement of fluorine atoms at the interface, form a low-adhesion surface; ceramic materials, through the densification of their crystal structure, enhance the stability of their textured structure at high temperatures. These three types of materials can be used alone or in combination to form multilayer composite structures, improving scratch resistance while reducing surface energy.

[0089] Through the above technical solutions, the surface of metal cooking utensils has better low surface energy characteristics, further improving the non-stick effect, and also further extending the service life of the textured structure, which can reduce the impact of mechanical scratches on the non-stick performance to a certain extent.

[0090] In some embodiments, the material of the metal substrate layer includes at least one of iron, stainless steel, aluminum, copper, and titanium.

[0091] The metal substrate layer refers to the metal material layer that constitutes the main structure of the cooking utensil, which can be one or a combination of iron, stainless steel, aluminum, copper, or titanium. Iron is alloyed to improve corrosion resistance, stainless steel is passivated with chromium to enhance structural strength, aluminum is pretreated with anodizing to improve surface adhesion, copper is treated with an anti-oxidation process to inhibit oxidation, and titanium is activated by plasma to improve deposition.

[0092] In some specific embodiments, the materials used may include metals such as iron, stainless steel, aluminum, copper, and titanium.

[0093] In some embodiments, the metal substrate layer includes a multilayer structure, i.e., a multilayer metal composite structure, such as a steel-aluminum-steel three-layer composite, a steel-aluminum two-layer composite, or a steel-aluminum-titanium combined inner pot structure. These materials or composite forms can be selected and applied according to actual needs.

[0094] In some embodiments, the textured structure includes a microstructure distributed on the surface of a metal substrate layer; a nanoparticle layer covers at least a portion of the microstructure to form a micro / nanostructure; wherein a hydrophobic material layer and the micro / nanostructure include polar covalent bonds.

[0095] Specifically, when the nanoparticle layer includes a nanocrystalline silicon layer, the silicon nanoparticles are randomly distributed on a biomimetic leaf vein textured surface (the uneven textured structure on the surface of the metal substrate layer) with a micron-scale rough structure to form a rough surface with micron-nano structures that are interlocked, further improving the hydrophobic properties of the original uneven textured surface. In addition, the silicon crystal layer can play a "rooting" role on the surface of the metal substrate layer, providing an anchor point for the strong bond between the metal substrate layer and the low surface energy hydrophobic material layer (especially the ceramic layer or the silicon-oxygen bonded material layer).

[0096] Specifically, when the hydrophobic material layer includes a silicon-oxygen layer, the "polar covalent bond" refers to the silicon-oxygen bond. In this bond, silicon atoms (electronegativity 1.90) and oxygen atoms (electronegativity 3.44) are bonded through shared electron pairs, but the electrons are biased towards the oxygen atom, resulting in polarity. The silicon-oxygen bonds within the silicon crystal layer form a three-dimensional network structure, creating a stable covalent crystal that enhances the hardness, scratch resistance, corrosion resistance, and thermal stability of the cookware surface coating.

[0097] The nanoparticle layer provides the silicon atom framework for the hydrophobic material layer, forming strong silicon-oxygen bonds with the hydrophobic material layer.

[0098] Fluorine- or silicon-containing low surface energy polymers are deposited on the surface of micro- or nanostructures using spraying, dip coating, or evaporation deposition methods. These polymers combine with the silicon crystal anchoring particles on the original surface and undergo a crystal catalytic reaction during heating, thereby improving the surface properties of the cookware and ultimately achieving extremely strong adhesion and non-stick properties.

[0099] On the other hand, embodiments of this application also provide a method for preparing a metal cooking utensil, comprising the following steps:

[0100] A textured structure resembling leaf veins is formed on the surface of a metal substrate through one of the following processes: embossing, etching, laser processing, or roughening.

[0101] A nanoparticle layer is deposited on the surface of the textured structure.

[0102] A hydrophobic material layer is formed on the surface of the nanoparticle layer by deposition through one of the following methods: spraying, dip coating, or evaporation deposition.

[0103] Among them, the biomimetic leaf vein-like textured structure refers to the formation of intersecting raised and recessed units on the metal surface by simulating the irregular branching shape of plant leaf veins, with a multidirectional spatial distribution. Specifically, leaf vein patterns can be pre-engraved using molds in embossing processes, or fractal paths can be formed by adjusting laser parameters to break the unidirectionality of traditional matrix arrangements, thereby dispersing frictional stress.

[0104] The deposition of nanoparticle layers refers to the formation of micro-nano composite structures composed of silicon-based or nitride materials on textured surfaces through physical vapor deposition, chemical vapor deposition, or electroplating. Magnetron sputtering can be used to control particle size and coverage, utilizing the rough surface of nanoparticles to increase the adhesion area of ​​hydrophobic materials while avoiding excessive particle accumulation that could bury the textured structure.

[0105] In this context, the deposition of hydrophobic materials refers to the formation of a continuous, low-surface-energy coating layer on the surface of a nanoparticle layer through spraying or vapor deposition processes. Organosilicon prepolymers can be cross-linked and cured under vacuum conditions, allowing the hydrophobic material to tightly fill the gaps between nanoparticles, forming a mechanically interlocked structure, thereby reducing interfacial energy and preventing oil film rupture.

[0106] Specifically, in the metal substrate processing stage, a combination of embossing and laser micro-engraving processes is used to first form the macroscopic leaf vein outline, and then refine the depth of local depressions, giving the texture both biomimetic morphology and mechanical strength. Subsequently, in a vacuum environment, by adjusting the substrate bias voltage and target current, nanoparticles are controlled to deposit on the texture surface in an oblique incident manner, forming a gradient-distributed rough layer. Finally, a fluoropolymer solution is sprayed at low temperature, utilizing capillary action to allow hydrophobic materials to penetrate into the gaps between the nanoparticles. After curing, a protective layer conforming to the texture is formed. "Conformal" means that the coating or film completely adheres to the shape of the substrate (here, the texture surface). This process sequence ensures that each functional layer is constructed sequentially, avoiding damage to the already formed structure during subsequent high-temperature processing.

[0107] The biomimetic leaf vein texture of this technical solution features a multi-directional branching structure that disperses frictional stress to the ridges in different directions, reducing the risk of linear failure. Furthermore, this solution increases the interfacial bonding area through a nanoparticle layer, extending the bonding between the hydrophobic material and the substrate from a two-dimensional plane to a three-dimensional anchor, significantly improving the coating's durability.

[0108] Through the above technical solution, this application solves the problems of poor scratch resistance caused by the obvious directionality of the micron-structure on the surface of pure metal cooking utensils, and the decline in non-stick performance caused by the easy peeling of the hydrophobic layer. The biomimetic leaf vein texture disperses frictional stress through multi-directional convex ribs, reducing the generation of linear scratches; the gradient deposition of the nanoparticle layer and the hydrophobic material forms a mechanically interlocking interface, preventing the coating from delaminating and peeling off during use. As a result, the hydrophobic properties of the metal substrate surface can be maintained for a long time, reducing the probability of direct contact between food and metal, thereby extending the non-stick life of the cooking utensils.

[0109] In some embodiments, the deposition conditions in the step of depositing a nanoparticle layer on the surface of the textured structure include: vacuum degree of 0.01 Pa-0.2 Pa, substrate bias voltage of 150 V-600 V, target current of 70-90 A, and temperature of 100-200 °C.

[0110] Specifically, taking the process of forming silicon-based nanoparticles on the surface of a metal texture layer as an example, it includes the following steps:

[0111] (1) Matrix ion cleaning: In an inert gas atmosphere (such as argon or helium), maintain a vacuum of 0.01Pa-0.1Pa, apply a matrix bias voltage of 500V-800V and a duty cycle of 60%-80% to perform plasma bombardment, remove surface contaminants and activate the metal matrix.

[0112] (2) Silicon-based particle deposition: using magnetron sputtering or chemical vapor deposition, maintaining a vacuum of 0.1Pa-0.5Pa in an inert gas environment, and generating silicon-based particles with a particle size of 50-1000nm at a substrate temperature of 100-250℃ by adjusting the substrate bias voltage of 100V-200V and the target current of 70A-90A, with the layer thickness controlled in the range of 0.05μm-2μm.

[0113] (3) In-situ surface functionalization: Nitrogen, oxygen or carbon source gas is introduced and plasma is used to bombard the surface particles under vacuum of 0.1Pa-0.3Pa to transform them into functional compounds such as silicon nitride, silicon oxide or silicon carbide.

[0114] The following description is based on specific embodiments.

[0115] Example 1

[0116] This embodiment provides a metal cooking utensil, the metal substrate layer of which is a 304-Al-430 three-layer composite inner pot, and its preparation steps are as follows:

[0117] (1) Biomimetic leaf vein texture processing: A biomimetic leaf vein texture structure is formed on the inner surface of the metal substrate layer (304 stainless steel surface) by embossing process. The raised rib units are irregularly distributed and have different projection shapes. The depth of the recessed units is 40μm. The surface is mechanically sanded.

[0118] (2) Nanoparticle layer deposition:

[0119] Ion cleaning: Argon atmosphere, vacuum degree 0.01Pa, Ar flow rate 200 sccm, matrix bias voltage 600V, duty cycle 70%, bombardment for 2 min;

[0120] Silicon particle deposition: The silicon target was turned on, Ar gas was used to maintain a vacuum of 0.15 Pa, substrate bias voltage was 150 V, duty cycle was 60%, target current was 80 A, temperature was 150 °C, and deposition was carried out for 10 min. Elemental silicon particles with a diameter of approximately 400 nm were formed, irregularly covering the textured surface, with a projected area coverage of 70% and a particle layer thickness of approximately 0.3 μm.

[0121] Surface nitriding: Nitrogen gas is introduced, vacuum degree 0.2 Pa, plasma bombardment causes silicon nitride phase to form on the surface of silicon particles;

[0122] (3) Hydrophobic material layer deposition: a siloxane-based ceramic coating is sprayed on the surface, with a thickness of 1.8 μm, to form a hydrophobic material layer; wherein, the hydrophobic material layer and the nanoparticle layer form a micro-nano structure on the textured surface.

[0123] Example 2

[0124] This embodiment provides a metal cooking utensil, which differs from Embodiment 1 in that:

[0125] (1) Metal substrate layer: 304 stainless steel substrate, the inner surface is laser-engraved to form a biomimetic leaf vein texture, the raised rib unit is irregularly branched and the projected shape is different, and the depth of the recessed unit is 50μm.

[0126] (2) Nanoparticle layer: Elemental silicon particles with a particle size of 300 nm, a coverage of 80%, and a layer thickness of 0.8 μm were deposited on the textured surface by magnetron sputtering; process parameters: vacuum degree 0.1 Pa, bias voltage 200 V, target current 75 A, temperature 150 °C.

[0127] (3) Hydrophobic material layer: sprayed polytetrafluoroethylene, with a layer thickness of 1.2μm.

[0128] Example 3

[0129] This embodiment provides a metal cooking utensil, which differs from Embodiment 1 in that the coverage of the nanoparticle projected area is 25%.

[0130] Example 4

[0131] This embodiment provides a metal cooking appliance, which differs from Embodiment 1 in that the silicon nitride material of the nanoparticle layer has a particle size of 200nm.

[0132] Example 5

[0133] This embodiment provides a metal cooking utensil, which differs from Embodiment 1 in that the hydrophobic material layer is replaced with an organosilicon polymer.

[0134] Example 6

[0135] This embodiment provides a metal cooking appliance, which differs from Embodiment 1 in that the silicon particles are not nitrided after deposition.

[0136] Comparative Example 1

[0137] The difference between this comparative example and Example 1 is that the hydrophobic material layer is directly sprayed onto the textured surface, without a nanoparticle layer.

[0138] Comparative Example 2

[0139] The difference between this comparative example and Example 1 is that the inner surface of the metal substrate layer is processed with regular matrix concave dots (non-biomimetic leaf veins).

[0140] Comparative Example 3

[0141] The difference between this comparative example and Example 1 is that the inner surface of the metal substrate layer has no surface texture.

[0142] Performance testing

[0143] To verify the progressiveness of the embodiments of this application, the samples of the embodiments and comparative examples were subjected to the following tests:

[0144] 1. Rice non-stick lifespan test

[0145] Test method: Take 2 cups of rice into each pot (3 cups for 30-type and 5 cups for 40-type / 50-type with silkscreened inner pot). Cook rice according to the normal method, adding the appropriate amount of rice and water, and turn on the power to cook rice (using the standard pot bottom temperature product and the standard rice-to-water ratio). After cooking, keep warm for 10 minutes. Invert the pot and check whether all the rice falls down when you use gravity or gently shake the inner pot to check the amount of rice residue in the inner pot. Continue cooking rice and count the number of times until it drops to level 2 non-stick or below (judgment standard: rice weight ≤ 50g is level 2 non-stick).

[0146] Test results are shown in Table 1.

[0147] Table 1

[0148]

[0149] Test Results Analysis: The three comparative examples show that both surface texture and the nanoparticle layer (silicon crystal layer) contribute to improving the non-stick lifespan of the inner pot. Surface texture primarily provides wear-resistant protection, while the silicon crystal layer enhances performance through strong bonding. The hardened silicon crystal layer can further improve the surface non-stick lifespan. Comparative Examples 2 and 3 also indicate that the irregularly distributed biomimetic leaf vein-shaped texture structure outperforms the regularly distributed texture structure in terms of non-stick performance. Therefore, by comprehensively utilizing the irregularly distributed microstructure, nanoparticle layer, and hydrophobic material layer, a longer-lasting non-stick effect can be achieved.

[0150] 2. Abrasion resistance test

[0151] Test method: Prepare a 5% detergent solution using dish soap. Use a 3M (7447C) scouring pad with a load of 2.5 kgf. Swing left and right for one stroke. Replace the scouring pad every 250 strokes. Check whether the coating exposes the substrate every 250 strokes (non-filled type: the test ends when ≥10 lines are exposed; filled type: the test ends when the coating peels off in flakes). Record the number of times the coating exposes the substrate.

[0152] Test results are shown in Table 2.

[0153] Table 2

[0154]

[0155] Test results analysis: Comparison of Example 3 and Comparative Example 4 shows that surface texture significantly improves wear resistance, while the hard silicon crystal layer also plays a role in wear resistance and scratch prevention.

[0156] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A metal cooking appliance characterized by, Comprise: A metal matrix layer provided with a concave-convex texture structure in the form of a biomimetic leaf vein, the concave-convex texture structure comprising a plurality of convex rib units and recessed units formed between the convex rib units, the planar projection shape of any two adjacent convex rib units in the vertical direction of the metal matrix layer surface is different; wherein the recessed unit comprises a plurality of interconnected grooves, the grooves extend along an irregular path and have a bifurcation structure; the depth of the grooves is distributed in a gradient increasing along the side area, the circular arc transition area to the bottom surface area of the inner surface of the pot, and / or the width of the grooves is distributed in a gradient decreasing along the side area, the circular arc transition area to the bottom surface area of the inner surface, so as to guide the water flow on the inner surface of the pot to be dispersed. A nanoparticle layer conformally covering the surface of the concave-convex texture structure; A hydrophobic material layer conformally covering the surface of the nanoparticle layer; Wherein, the concave-convex texture structure comprises a microstructure distributed on the surface of the metal matrix layer; the nanoparticle layer covers at least part of the microstructure to form a micro-nano structure; wherein the hydrophobic material layer and the micro-nano structure comprise a polar covalent bond.

2. The metal cooking appliance of claim 1, wherein, The depth of the recessed unit is not more than one-fourth of the thickness of the metal matrix layer; and / or the depth of the recessed unit ranges from 10μm to 100μm.

3. The metal cooking appliance of claim 1, wherein, The nanoparticle layer contains nanoparticles, the material of the nanoparticles includes at least one of elemental silicon, silicon oxide, silicon nitride, tungsten nitride, and zirconium nitride, and the particle size of the nanoparticles ranges from 50nm to 1000nm.

4. The metal cooking appliance of claim 3, wherein, The projection area coverage rate of the nanoparticles on the surface of the concave-convex texture structure in the vertical direction is 20%-90%.

5. The metal cooking appliance of claim 1, wherein, The thickness of the nanoparticle layer ranges from 0.05μm to 2μm; and / or the thickness of the hydrophobic material layer ranges from 0.05μm to 5μm.

6. The metal cooking appliance of claim 1, wherein, The material of the hydrophobic material layer includes at least one of organic silicon polymer, fluorine-containing polymer, and ceramic.

7. The metal cooking appliance of claim 1, wherein, The material of the metal matrix layer includes at least one of iron, stainless steel, aluminum, copper, and titanium, and / or the metal matrix layer comprises a multi-layer structure.

8. A method of producing a metal cooking appliance according to any one of claims 1 to 7, characterized in that, Comprise the following steps: Form a concave-convex texture structure in the form of a biomimetic leaf vein on the surface of a metal matrix by one of embossing, etching, laser, or roughening process; Depositing a nanoparticle layer on the surface of the concave-convex texture structure; Depositing a hydrophobic material layer on the surface of the nanoparticle layer by one of spraying, dipping, or evaporation plating.

9. The method for preparing the metal cooking utensil as described in claim 8, characterized in that, In the step of depositing a nanoparticle layer on the surface of the concave-convex texture structure, the deposition conditions include: vacuum degree 0.01Pa-0.2Pa, substrate bias 150V-600V; target current 70-90A, temperature 100-200℃.

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