CN115161580A

CN115161580A - Non-stick coating, preparation method thereof and cookware comprising non-stick coating

Info

Publication number: CN115161580A
Application number: CN202111051023.1A
Authority: CN
Inventors: 李超; 瞿义生; 袁华庭; 张明
Original assignee: Wuhan Supor Cookware Co Ltd
Current assignee: Wuhan Supor Cookware Co Ltd
Priority date: 2021-09-08
Filing date: 2021-09-08
Publication date: 2022-10-11
Anticipated expiration: 2041-09-08
Also published as: CN115161580B

Abstract

The application provides a non-stick coating, a preparation method thereof and a cooker comprising the non-stick coating, wherein the preparation method comprises the following steps: forming a thermal sprayed coating by thermally spraying alloy powder on a surface of a substrate; performing heat preservation on the thermal spraying coating; laser remelting is adopted to completely melt the surface layer of the thermal spraying coating after heat preservation, so that the thermal spraying coating is formed to comprise a melting layer and a transition layer; and rapidly cooling the melting layer, thereby forming a non-stick layer with an amorphous structure on the surface of the substrate. The non-stick coating obtained by the preparation method has good wear resistance, lasting non-stick property and good bonding force with a substrate, and has low requirements on the preparation process.

Description

Non-stick coating, preparation method thereof and cookware comprising non-stick coating

Technical Field

The application relates to the field of kitchen utensils, in particular to a non-stick coating, a preparation method thereof and a pot comprising the non-stick coating.

Background

Since the cooker never sticks to a pot, food can not stick to the pot bottom when the food is cooked, so that the phenomenon that the food sticks to the pot often in the cooking process of the traditional cooker can be avoided, the food is prevented from being burnt, and the problem of harmful substances caused by burnt food can be avoided. Moreover, the non-stick pan not only reduces the cleaning difficulty of the pan, but also can easily fry and fry food, and can avoid the problem that the traditional pan needs more grease to prevent the food from sticking to the pan, thereby reducing the oil consumption to the maximum extent, reducing the fat intake of people, and complying with the consumption trend of modern people pursuing low fat and low heat. Therefore, non-stick pans are the first choice for many households.

The cookware on the market is mainly non-stick by coating a non-stick layer on the inner surface of the cookware, wherein fluorine paint, ceramic paint and organic silicon resin paint are common non-stick layers. Although the fluorine paint, the ceramic paint and the organic silicon resin paint can be used as non-stick layers of cookware, the problems are obvious in the using process. For example, a non-stick layer formed of a fluorine paint is not wear-resistant and easily decomposes harmful substances at high temperatures; the non-stick layer formed by the ceramic coating has poor durability and non-stick property, and is easy to fall off after being used for 3 to 6 months; the non-stick layer formed by the organic silicon resin coating is easy to yellow or gray under the condition of high temperature or open fire, and the hardness of the non-stick layer is reduced at high temperature, so that the phenomenon of 'back sticking' is easy to generate.

Disclosure of Invention

To address one or more of the above-mentioned problems, the present invention provides a non-stick coating having durable non-stick properties and wear resistance.

To this end, a first aspect of the present application is to provide a method of preparing a non-stick coating.

A second aspect of the present application is to provide a non-stick coating.

A third aspect of the present application is to provide a cookware comprising a non-stick coating.

To achieve the above object, embodiments of the first aspect of the present application provide a method for preparing a non-stick coating, comprising the steps of: forming a thermal sprayed coating by thermally spraying an alloy powder on a surface of a substrate; preserving the heat of the thermal spraying coating; laser remelting is adopted to completely melt the surface layer of the thermal spraying coating after heat preservation, so that the thermal spraying coating is formed to comprise a melting layer and a transition layer; and rapidly cooling the molten layer to form a non-stick layer with an amorphous structure on the surface of the substrate. The preparation method can avoid the crystallization phenomenon of the amorphous structure in the process of forming the non-stick coating containing the amorphous structure by adopting the alloy powder containing the amorphous structure through thermal spraying, reduces the requirements of the thermal spraying process and the requirements on the selection of raw material alloy powder, reduces the preparation cost to a certain extent, has simple preparation process of the non-stick coating, and is easy to realize batch production.

In some embodiments, the rapid cooling step may be performed using liquid nitrogen, wherein, in the rapid cooling step, the cooling rate may be not less than 10 ⁴ K/s. Under the condition, atoms in the melting layer can be quickly frozen, and the atoms in the melting layer are prevented from crystallizing, so that an amorphous state in the melting layer is cooled to form an amorphous structure, and finally the non-stick layer containing the amorphous structure is obtained.

In some embodiments, in the maintaining step, the maintaining temperature may be 350 ℃ to 450 ℃ and the maintaining time may be at least 20min. Through the mode of heat preservation, make the thermal stress in the thermal spraying coating reduce, avoid the thermal spraying coating can not expand and contract freely that the thermal stress is too big in the thermal spraying coating to prevent that the thermal spraying coating from producing the crackle when the non-stick layer is formed in the cooling of melting layer, avoid the non-stick coating that obtains to take place fracture and drop scheduling problem finally.

In some embodiments, the thickness of the thermal spray coating may be 100 μm to 800 μm, wherein the melting layer may be formed to have a thickness of 30% to 60% of the thickness of the thermal spray coating. In this embodiment, laser only remelts the top layer of hot spraying coating, and the top layer after the remelting forms the melting layer, and the great problem that leads to hot spraying coating and base member to warp of the difference in temperature between melting layer and the base member when avoiding the melting layer cooling to form the non-stick layer, consequently, the thickness of melting layer is less than the thickness of hot spraying coating and can prevent to a certain extent that the cohesion between hot spraying coating and the base member reduces the problem that the non-stick coating that leads to forming drops in the use.

In some embodiments, the alloy powder may have a particle size of 300 to 800 mesh. The alloy powder in the particle size range can be heated and melted during thermal spraying to form a thermal spraying coating, and the formed thermal spraying coating has good compactness and low impurity content.

In some embodiments, the alloy powder may include at least one of stainless steel powder, zr alloy powder, cu alloy powder, al alloy powder, mg alloy powder, ti alloy powder, and isoatomic ratio high-entropy alloy powder.

In some embodiments, the alloy powder may include stainless steel powder and/or zirconium alloy powder. The alloy powder in the embodiment has strong non-crystallizing capability, is beneficial to obtaining a non-stick layer with high content of an amorphous structure, further reduces the surface energy of the non-stick layer, and enables the obtained non-stick coating to show excellent non-stick property.

In some embodiments, the base may be a base of a cookware.

Embodiments of a second aspect of the present application provide a non-stick coating comprising: a transition layer on a surface of the substrate, the transition layer having a crystalline structure; the non-stick layer is located on the surface of the transition layer and has an amorphous structure, the thickness of the non-stick layer is 30% -60% of the total thickness of the non-stick layer, and the transition layer and the non-stick layer have the same constituent elements. The embodiment is provided with the transition layer between on-stick layer and base member, and the transition layer forms the buffering to the difference in temperature between melting layer and the base member when the melting layer cools off and forms on-stick layer to avoid the too big deformation that takes place between hot spraying coating and the base member that leads to of difference in temperature, consequently, keep the cohesion between hot spraying coating and the base member not changing to a certain extent, prolong the life of the on-stick coating of preparation.

In some embodiments, the thickness of the thermal spray coating may be 100 to 800 μm. The non-stick coating formed by the thermal spraying coating in the range has good wear resistance, and can avoid the problem that the thermal expansion coefficient of the substrate and the coating is inconsistent and cracks are easily caused due to large temperature difference when the melting layer is cooled and converted into the non-stick coating, and also avoid the defects of cracks and the like caused by thermal stress generated by the fact that the coating thickness is too thick and heat is easily accumulated.

Embodiments of a third aspect of the present application provide a non-stick coating comprising a substrate and the above-described non-stick coating.

Drawings

Fig. 1 shows a schematic view of the preparation of a non-stick coating according to the present application.

Description of reference numerals:

110-thermal spray coating, 120-liquid nitrogen, 130-substrate.

Detailed Description

The concepts of the present invention will now be described more fully hereinafter.

The principle of realizing non-stick of the non-stick pan mainly comprises three aspects: (1) the surface of the cookware itself has low surface energy; (2) A microscopic concave-convex structure is formed on the surface of the pot, and the concave-convex structure forms a hydrophobic and oleophobic surface similar to a lotus leaf; (3) The surface of the pot is coated with the porous oil storage material to form a stable oil film, and the formed oil film is utilized to realize non-sticking of the pot.

The inventor finds that the amorphous alloy (namely, the liquid metal with an amorphous structure) has lower surface energy and shows good non-stick property compared with the common material in the research process of different materials; the inventor further analyzes the reasons for the generation and finds that the low surface energy of the amorphous alloy is caused by the amorphous structure of the amorphous alloy, and the amorphous alloy has the characteristics of long-range disorder and short-range order.

In contrast, the non-stick property of the cookware is realized by attaching a layer of coating with an amorphous structure on the inner surface of the cookware. Experiments show that the alloy powder with the amorphous structure can be sprayed on the inner surface of a cooker by a thermal spraying mode to form the non-stick coating with the amorphous structure, but the non-stick property of the formed non-stick coating can be changed along with the thermal spraying condition, and the non-stick property of the non-stick coating can be reduced to a certain extent. Further research on the reason why the non-stick property of the non-stick coating formed by thermal spraying is reduced shows that the amorphous structure in the alloy generally has the tendency of crystallization along with the increase of the temperature of the thermal spraying and the prolonging of the spraying time in the process of the thermal spraying, so that the proportion of the amorphous structure in the non-stick coating is reduced, the surface energy of the non-stick coating is increased, and the non-stick property of the non-stick coating is reduced; therefore, the requirement on the thermal spraying process is higher when the alloy powder containing the amorphous structure is sprayed on the surface of the cookware base body in a thermal spraying manner to form the non-stick coating.

The application provides a preparation method of a non-stick coating. The method of making the non-stick coating according to the present application will be described in detail below with reference to fig. 1. Fig. 1 shows a schematic diagram of the preparation of a non-stick coating.

According to the present application, the method of preparing the non-stick coating may comprise the steps of: spraying alloy powder on the surface of the substrate by adopting a thermal spraying process, thereby forming a thermal spraying coating on the surface of the substrate; preserving the heat of the formed thermal spraying coating; laser remelting is adopted to completely melt the surface layer of the thermal spraying coating after heat preservation so as to form a melting layer; the melted layer is rapidly cooled to form a non-stick coating having an amorphous structure on the surface of the substrate.

In an embodiment of the application, the base may be a base of a pot. The surface of the substrate may be pretreated, e.g., cleaned, prior to performing the thermal spray to roughen the surface of the substrate to enhance the bonding force between the substrate and the non-stick layer to be formed.

According to the embodiments of the present application, the alloy powder forming the thermal spray coating may be crystalline alloy powder or amorphous alloy powder. According to some embodiments of the present application, the alloy powder may include at least one of stainless steel powder, zr alloy powder, cu alloy powder, al alloy powder, mg alloy powder, ti alloy powder, and isoatomic high-entropy alloy powder. According to the present application, the thermal spray coating may be formed on the inner surface of the pot base by thermal spraying. Preferably, the alloy powder may use stainless steel powder and/or Zr alloy powder. The non-crystallization cooling speed is low if the non-crystallization capacity of the alloy powder is strong; the stronger the amorphizing ability of the alloy powder, the easier it is to obtain an alloy with a high amorphous content. The thermal spray process may include plasma spraying, however, the application is not limited thereto and one skilled in the art may select a suitable thermal spray process to form the thermal spray coating in light of the teachings of the present inventive concept.

According to embodiments of the present application, the alloy powder may have a particle size of 300 to 800 mesh. Specifically, if the alloy powder is too coarse, the powder is insufficiently melted by heat during flight during thermal spraying, and is less deformed when reaching the surface of the substrate, resulting in incompact thermal spray coating and easy occurrence of defects such as poor wear resistance and durability non-stick property of the thermal spray coating; on the other hand, if the alloy powder is too fine, the alloy powder is easily excessively oxidized during thermal spraying, and thus a large amount of oxide impurities may be introduced into the formed thermal spray coating to degrade the performance of the thermal spray coating.

According to embodiments of the present application, the thickness of the thermal spray coating formed on the surface (e.g., inner surface) of the substrate (e.g., cookware substrate) may be in the range of 100 μm to 800 μm. Since thermal stress generally exists in a coating formed by thermal spraying, if the thermal spraying coating is too thick, the coating is easy to generate heat accumulation during the preparation process and the use process of a pot tool to generate thermal stress, so that the thermal spraying coating has defects of cracks and the like, and therefore, the thickness of the thermal spraying coating cannot exceed 800 mu m. On the other hand, if the thickness of the thermal spray coating is less than 100 μm, chipping is likely to occur due to inconsistency in the thermal expansion coefficients of the substrate and the coating due to a large temperature difference when the coating is quenched for amorphization, since the thickness of the coating is too thin and the wear life is poor. Further, in the present embodiment, the thermal spraying process may be a plasma spraying process.

According to embodiments of the present application, after forming a thermal spray coating on a surface forming a substrate and before performing laser remelting, the coating needs to be incubated. In particular, thermal stress is weakened in the thermal spray coating by means of heat preservation because the thermal spray coating usually has thermal stress, and the thermal stress causes the thermal spray coating not to freely expand and contract, so that the thermal spray coating cracks and falls off. That is, the thermal spray coating is maintained for a period of time after the thermal spray coating is formed, so that thermal stress in the thermal spray coating is slowly released during the thermal maintenance, thereby finally completely or substantially releasing or minimizing thermal stress in the thermal spray coating, and further preventing cracks from being generated in the thermal spray coating when a molten layer formed by laser remelting is subsequently cooled to form an anti-stick layer. According to embodiments of the present application, the thermal spray coating may be held for at least 20 minutes to release thermal stresses in the thermal spray coating as much as possible.

In some embodiments of the present application, the incubation temperature may be controlled at 350 ℃ to 450 ℃. Specifically, according to the application, the temperature of the just-formed thermal spray coating can be 550-650 ℃, and if the heat preservation temperature is lower than 350 ℃, the surface of the thermal spray coating dissipates heat quickly due to the large temperature difference between the heat preservation temperature and the temperature of the thermal spray coating, so that the difference of the thermal expansion rate between the surface of the thermal spray coating and the inner part of the thermal spray coating is large, and the thermal stress in the thermal spray coating cannot be eliminated finally; and if the holding temperature is too high (higher than 650 ℃), the economy is poor. Thus, the temperature used to thermally insulate the thermal spray coating may range from 350 ℃ to 450 ℃.

According to an embodiment of the present application, after the thermal spray coating formed on the surface of the substrate is thermally insulated, laser remelting may be performed. Specifically, the laser is mainly used for remelting the surface layer of the thermal spraying coating, so that the remelted surface layer in the coating forms a melting layer which is converted into an amorphous tissue layer in the subsequent process, and the bottom layer of the coating is an unmelted area which serves as a transition layer. In this embodiment, the original crystalline structure in the surface layer of the thermal spray coating is destroyed by laser remelting to make it amorphous, and the molten layer in the amorphous state is cooled to form a non-stick layer containing an amorphous structure. Because the thermal spraying coating with a certain thickness is reserved as the transition layer during laser remelting, the transition layer can form buffer between the melting layer and the substrate when the melting layer is cooled, so that the problem that the thermal spraying coating and the substrate deform due to large temperature difference is avoided, and therefore, the transition layer at least allows heat to keep the binding force between the thermal spraying coating and the substrate unchanged to a certain extent, so that the formed non-stick coating is prevented from falling off in the using process.

In some embodiments according to the present application, the thickness of the melt layer may optionally be controlled to be 30% to 60% of the total thickness of the thermal spray coating. If the thickness of the melting layer is too large, the thickness of the transition layer is too small, resulting in a less obvious cushioning effect; if the thickness of the melting layer is too small, the thickness of the amorphous layer is too small, so that the wear-resisting service life of the non-stick coating is poor, and the transition layer with the thickness avoids the problem that the buffer effect is not obvious because the thickness of the transition layer is too small.

According to a preferred embodiment of the present application, the step of laser remelting the surface layer of the thermally sprayed coating may employ the following parameters: the laser power is 500W-2 KW, the diameter of a light spot is 3 mm-10 mm, the lap joint rate is 40% -50%, the gas protection method is argon protection, and the scanning speed is 10 m/min-15 m/min.

According to the embodiment of the application, after the surface of the thermal spray coating is formed into the molten layer, the molten layer is subjected to rapid cooling (i.e., rapid cooling), and in the process, atoms in the molten layer gradually lose kinetic energy along with the reduction of the temperature, so that the molten layer is prevented from crystallizing, and finally the atoms in the molten layer are frozen down to form the non-stick layer with an amorphous structure. According to some embodiments of the present application, the step of rapidly cooling the molten layer may be performed using liquid nitrogen. According to a preferred embodiment of the present invention, the cooling rate for cooling the molten layer may be controlled to be 10 or more ⁴ K/s. As shown in FIG. 1, thermal spray formed on substrate 130 may be utilized with liquid nitrogen 120The melted layer on the surface of the coating layer 110 is quenched. However, the present application is not limited thereto, and those skilled in the art may select other media to quench the molten layer under the teachings of the present application. Here, when liquid nitrogen is selected for cooling the melt layer, the cooling conditions for the melt layer include: the flow rate of the liquid nitrogen is 6-12L/min, and the pressure is 0.1MPa, wherein the flow rate of the liquid nitrogen refers to the flow rate of the liquid nitrogen sprayed from a nozzle with the diameter of 10 mm.

The non-stick coating formed on the surface (e.g., inner surface) of the base body according to the above method includes an alloy coating (i.e., a transition layer) on the surface of the base body which is not remelted and a non-stick layer having an amorphous structure on the transition layer which is formed by cooling the melt layer, so that the obtained non-stick coating produces a non-stick effect.

According to the method, the problem of amorphous turning crystallization in the process of forming the non-stick coating with the amorphous structure by adopting the amorphous alloy powder through thermal spraying can be avoided, so that the non-stick layer prepared by adopting the method is high in amorphous content, low in surface energy and excellent in non-stick property, and the requirement on a thermal spraying process is reduced. Further, an amorphous alloy (i.e., a liquid metal having an amorphous structure) is a disordered structure having no structural defects such as grain boundaries, twin crystals, lattice defects, dislocations, and dislocations, as in a crystal alloy, and having no fluctuation in phase difference, precipitates, segregation, and other components, and has a high degree of chemical uniformity, no plastic deformation such as grain boundary slip when subjected to an external force, and a high strength. Thus, the non-stick coating obtained exhibits excellent wear resistance as well as long-lasting non-stick properties.

The present application provides a non-stick coating that can be formed on the inner surface of a cookware. Referring to fig. 1, the non-stick coating may include: a transition layer (not shown) on a surface of the base 130, the transition layer having a crystalline structure; and a non-stick layer (not shown) on the surface of the transition layer, the non-stick layer having an amorphous structure, the thickness of the non-stick layer being 30% to 60% of the total thickness of the non-stick layer, wherein the transition layer and the non-stick layer have the same constituent elements. According to the application, through set up the transition layer between on-stick layer and base member, can form the buffering when preparing on-stick layer, avoid forming on-stick layer's melting layer because of the too big coating that leads to hot spraying to form of difference in temperature takes place to warp with the base member when rapid cooling, keeps the cohesion between hot spraying coating and the base member not to change to a certain extent, prolongs the life of the on-stick coating of preparation. In addition, the non-stick layer and the transition layer are formed by the same thermal spraying coating, so the non-stick layer and the transition layer are integrated.

The following detailed description is provided to illustrate embodiments of the invention.

Example 1

The preparation method of the non-stick coating specifically comprises the following steps:

step C1, preparation of thermal spray coating

Firstly, a substrate is cleaned by a surfactant Acksu 226SA, then dried, and then the surface of the substrate is subjected to sand blasting, wherein the roughness Ra of the surface of the substrate after the sand blasting is 3 mu m.

Secondly, preheating the matrix subjected to sand blasting treatment by using a heating furnace to 260 ℃.

Finally, stainless steel powder (which is commercially available common 316 stainless steel powder) with the particle size of 300 meshes is sprayed on the inner surface of the substrate in a plasma spraying mode to form a thermal spraying coating with the thickness of 160 mu m, and the parameters during plasma spraying are as follows: the powder feeding speed is 35g/min; the spraying distance is 148mm; arc current 520A; the hydrogen pressure is 0.5MPa, and the flow is 7.5L/min; the argon pressure is 0.8MPa, and the flow is 50L/min.

Step C2, preparation of non-stick layer

Firstly, the formed thermal spray coating is kept at the temperature of 350 ℃ for 20min.

Secondly, performing laser remelting on the surface layer of the thermal spraying coating after heat preservation, wherein the thickness of the melting layer is 30% of that of the thermal spraying coating; the laser remelting conditions are as follows: laser power: 1.1KW; spot size: the diameter of the light spot is 7mm; the lap joint rate: 45%, gas protection method: argon protection; scanning rate: 12m/min.

Finally, the molten layer was melted with liquid nitrogen at 2.1X 10 ⁴ The cooling speed of K/s is used for cooling, and the non-stick layer with an amorphous structure is formed, so that the non-stick coating comprising the transition layer and the non-stick layer is obtained.

Example 2

A non-stick coating was prepared in the same manner as in example 1, except that the following conditions were different: the granularity of the stainless steel powder used in the step C1 is 800 meshes, and the thickness of the formed thermal spraying coating is 790 mu m; the thermal spraying coating in the step C2 has the heat preservation temperature of 420 ℃, the heat preservation time of 75min, the thickness of the melting layer of 58 percent of that of the thermal spraying coating, and the liquid nitrogen is used for heating to 3.4 multiplied by 10 ⁴ The melt layer is cooled at a cooling rate of K/s.

Example 3

A non-stick coating was prepared in the same manner as in example 1, except that the following conditions were different: the granularity of the stainless steel powder in the step C1 is 600 meshes, and the thickness of the formed thermal spraying coating is 500 mu m; the heat preservation temperature of the thermal spraying coating in the step C2 is 400 ℃, the heat preservation time is 75min, and the thickness of the melting layer is 45% of that of the thermal spraying coating.

Example 4

A non-stick coating was prepared in the same manner as in example 1, except that the following conditions were different: the granularity of the stainless steel powder in the step C1 is 600 meshes, and the thickness of the formed thermal spraying coating is 650 mu m; the heat preservation temperature of the thermal spraying coating in the step C2 is 370 ℃, the heat preservation time is 60min, the thickness of the melting layer is 50 percent of that of the thermal spraying coating, and the liquid nitrogen is used for heating at 2.4 multiplied by 10 ⁴ The melt layer is cooled at a cooling rate of K/s.

Comparative example 1

A non-stick coating was prepared in the same manner as in example 4, except that the thermal spray coating was not incubated in step C2.

Comparative example 2

Except that in step C2 liquid nitrogen is used to control the reaction at 0.7X 10 ⁴ Cooling the molten layer at a cooling rate of K/sA non-stick coating was prepared in the same manner as in example 4.

Comparative example 3

The non-stick coating was prepared in the same manner as in example 4, except that the thermal spray coating was entirely remelted by the laser in step C2.

Comparative example 4

Preparation of the first coating:

firstly, the substrate is cleaned by an alkaline solvent, cleaned and dried, and then the surface of the substrate is subjected to sand blasting treatment, wherein the roughness Ra of the surface of the substrate after the sand blasting treatment is 3 mu m.

Secondly, preheating the pot body matrix subjected to sand blasting by using a heating furnace to 260 ℃.

Finally, stainless steel powder with the grain size of 600 meshes was sprayed on the surface of the substrate by means of plasma spraying, thereby forming a first coating on the surface of the substrate, the thickness of the formed first coating being 325 μm, and the parameters during plasma spraying were the same as those in example 1.

Preparation of the second coating:

after the temperature of the first coating is reduced to 280 ℃, fe40-Zr25-Cr9-B6-Cu15-Y5 amorphous alloy with the granularity of 600 meshes is sprayed on the surface of the first coating in a plasma mode, a second coating with an amorphous structure is formed on the surface of the first coating, the thickness of the second coating is 325 mu m, and finally the non-stick coating comprising the first coating and the second coating is obtained.

Performance index testing

The non-stick coatings prepared in examples 1-4 and comparative examples 1-4 were tested for their performance and the results are reported in table 1 below.

(1) Non-tackiness detection

The non-stick property of the non-stick coating is detected by adopting a non-stick property test method for the non-stick coating in the national standard GB/T32095 according to the non-stick property test of the fried egg. The adhesion between the omelette and the coating was examined and the non-stick properties of the coating were classified into the following three grades:

excellent (∘): the eggs can be taken out without damage by a plastic shovel and no residue is left.

Good (excellent): the eggs could not be removed without injury with a plastic spatula, but the residue was removed by gentle rubbing with a wet sponge.

Poor (×): residue was not removed by light wiping with a wet sponge.

(2) Permanent tack free test

The permanent non-adhesiveness detection is carried out according to a GB/T32095.2 middle plane wear-resistant test method, the egg frying test is carried out once every 1000 times of grinding, the test is finished when the 'poor (x)' grade appears in the egg frying for two continuous times, and the wear-resistant times are recorded.

(3) Abrasion resistance test

And (4) recording the wear-resisting times of the non-stick coating worn through the exposed bottom by referring to a plane wear-resisting test method in GB/T32095.2.

(4) Binding Strength detection

The bonding strength between the non-stick coatings prepared in the above examples and comparative examples and the substrate was analyzed by the hot and cold impact method, and the specific test method is as follows: the substrate with the non-stick coating was first heated to 260 ℃ and held for 30min and then immediately placed in cold water at 20 ℃ with heating, holding and cooling as a cycle. The standard of the cookware of the enterprise is that the coating and the matrix are still not damaged and qualified after being subjected to 50 times of cold and hot impact.

TABLE 1 Performance index test results

As can be seen from example 4 and comparative example 1 in Table 1, the bonding force between the non-stick coating formed after the thermal spraying coating is insulated and the cookware substrate is better. It can be seen from example 4 and comparative example 2 in table 1 that, when the cooling rate is too low, the abrasion resistance and the permanent non-tackiness of the formed non-stick coating are significantly reduced, because when the cooling rate is too low, the disordered atoms in the melted layer are crystallized, and the crystal structure content in the formed non-stick layer is high, resulting in the reduction of the abrasion resistance and the permanent non-tackiness of the prepared non-stick coating. As can be seen from example 4 and comparative example 3 in table 1, the bonding strength between the non-stick coating formed after the thermal spray coating is completely remelted by the laser and the substrate is small because there is no transition layer as a buffer when the laser remelted coating is cooled, and the bonding force between the obtained non-stick coating and the substrate becomes weak because the coating and the substrate are deformed due to a large temperature difference.

As can be seen from example 4 and comparative example 4 in table 1, the non-stick coating prepared by the present application has better durable non-stick property, wear resistance and bonding strength with the substrate than the non-stick coating prepared by comparative example 4, and the reason is mainly two-fold, on one hand, the transition layer and the non-stick layer in the non-stick coating prepared by the present application are formed by the same thermal spray coating, while the first coating and the second coating in the non-stick coating in the comparative example are separately formed by plasma spraying, resulting in poorer bonding strength between the non-stick coating and the substrate in the comparative example 4; on the other hand, the non-stick layer in the non-stick coating in the present application is formed by cooling the melt layer and has a higher amorphous content, while the second coating in comparative example 4 is formed by plasma spraying, in which a part of the amorphous structure in the alloy powder is crystallized, resulting in a decrease in both wear resistance and permanent non-stick property of the formed non-stick coating.

In summary, as can be seen from the above table 1, the non-stick coating prepared by the method of the present application shows excellent non-stick property, wear resistance, durable non-stick property and better bonding strength with the substrate. The reason is that the bonding force between the non-stick coating provided with the transition layer and the substrate is better, because the transition layer reduces the deformation of the coating and the substrate caused by the larger temperature difference between the coating and the substrate when the non-stick layer is prepared, so that the bonding force between the thermal spraying coating and the substrate is at least kept unchanged to a certain extent by the transition layer, and the formed non-stick coating has more excellent bonding strength with the substrate. In addition, the thermal stress in the thermal spraying coating is reduced by heat preservation, and the non-stick coating in service is observed, so that the non-stick coating prepared after heat preservation is not easy to crack.

According to the above description, the non-stick coating and the preparation method thereof of the present application have the following advantages:

(1) Remelting the surface layer of the formed thermal spraying coating, cooling the melting layer to form a non-stick layer with an amorphous structure, wherein the formed non-stick layer has high amorphous content and low surface energy, good non-stick effect is achieved, and meanwhile, the requirement on a plasma spraying process is reduced. In addition, the preparation of the non-stick coating in the application also has the characteristics of simple process and easy realization of batch production.

(2) The non-stick coating also comprises a transition layer, and the transition layer is arranged between the non-stick layer and the base body, so that the deformation of the thermal spraying coating and the base body caused by the large temperature difference between the thermal spraying coating and the base body during the preparation of the non-stick coating is reduced, and the formed non-stick coating is firmly attached to the base body. In addition, the preparation process of the non-stick coating also adopts a heat preservation mode to reduce the thermal stress in the thermal spraying coating, prevent the thermal spraying coating from generating cracks when the melting layer is cooled to form the non-stick coating, and prolong the service time of the non-stick coating.

While the foregoing is directed to embodiments of the present application, and certain embodiments shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments (e.g., where different features described in different embodiments may be combined), and that such changes and modifications may be made without departing from the principles and spirit of the application, the scope of which is defined in the claims and their equivalents.

Claims

1. A method for preparing a non-stick coating, characterized in that it comprises the following steps:

forming a thermal sprayed coating by thermally spraying alloy powder on a surface of a substrate;

performing heat preservation on the thermal spraying coating;

laser remelting is adopted to completely melt the surface layer of the thermal spraying coating after heat preservation, so that the thermal spraying coating is formed to comprise a melting layer and a transition layer;

and rapidly cooling the melting layer, thereby forming a non-stick layer with an amorphous structure on the surface of the substrate.

2. The production method according to claim 1, wherein the rapid cooling step is performed using liquid nitrogen, and wherein, in the rapid cooling step, the cooling rate is not less than 10 ⁴ K/s。

3. The method according to claim 1, wherein in the keeping step, the keeping temperature is 350 ℃ to 450 ℃ and the keeping time is at least 20min.

4. The production method according to claim 1, wherein the thickness of the thermal spray coating is 100 to 800 μm, and wherein the thickness of the melt layer formed is 30 to 60% of the thickness of the thermal spray coating.

5. The production method according to claim 1, wherein the particle size of the alloy powder is 300 to 800 mesh.

6. The production method according to claim 1, characterized in that the alloy powder includes at least one of stainless steel powder, zr alloy powder, cu alloy powder, al alloy powder, mg alloy powder, ti alloy powder, and isoatomic ratio high-entropy alloy powder.

7. The production method according to claim 6, characterized in that the alloy powder includes stainless steel powder and/or Zr alloy powder.

8. The method of claim 1, wherein the base is a base of a pot.

9. A non-stick coating, characterized in that it comprises:

a transition layer on a surface of the substrate, the transition layer having a crystalline structure;

the non-stick layer is positioned on the surface of the transition layer, the non-stick layer has an amorphous structure, the thickness of the non-stick layer is 30-60% of the total thickness of the non-stick coating,

wherein the transition layer and the non-stick layer have the same constituent elements.

10. The non-stick coating according to claim 9, characterized in that it has a thickness comprised between 100 and 800 μm.

11. A cookware, characterized in that it comprises a base and a non-stick coating according to claim 9.