CN108968701B - Non-stick coating, preparation method thereof, pot and cooking equipment - Google Patents
Non-stick coating, preparation method thereof, pot and cooking equipment Download PDFInfo
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- CN108968701B CN108968701B CN201710405527.6A CN201710405527A CN108968701B CN 108968701 B CN108968701 B CN 108968701B CN 201710405527 A CN201710405527 A CN 201710405527A CN 108968701 B CN108968701 B CN 108968701B
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- A—HUMAN NECESSITIES
- A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
- A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
- A47J36/00—Parts, details or accessories of cooking-vessels
- A47J36/02—Selection of specific materials, e.g. heavy bottoms with copper inlay or with insulating inlay
- A47J36/025—Vessels with non-stick features, e.g. coatings
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/62—Plasma-deposition of organic layers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
- B05D5/08—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface
- B05D5/083—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface involving the use of fluoropolymers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
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Abstract
The invention relates to the technical field of electric heating appliances, and discloses a non-stick coating, a preparation method thereof, a pot and cooking equipment. The method comprises the following steps: (1) pretreating a substrate; (2) carrying out optional preheating treatment on the surface of the substrate obtained in the step (1); (3) taking ceramic powder and fluorine-containing resin powder as raw materials, and forming a non-stick coating on the surface of a substrate through plasma spraying treatment; wherein, in the step of the plasma spraying treatment, a flame flow formed by a plasma spray gun is adopted, and ceramic powder is fed in the formed flame flow at a distance D1 from an outlet of the spray gun, fluorine-containing resin powder is fed at a distance D2 from the outlet of the spray gun, wherein D2 is larger than D1, and the weight ratio of the powder feeding amount of the fluorine-containing resin powder to the powder feeding amount of the ceramic powder is 0.14-0.3: 1. the non-stick coating has the advantages of high surface hardness, high coating binding force and the like.
Description
Technical Field
The invention relates to the technical field of electric heating appliances, in particular to a non-stick coating, a preparation method thereof, a pot and cooking equipment.
Background
The existing non-stick coating is mainly a Teflon PTFE non-stick coating or a ceramic non-stick coating, the conventional forming modes of the coatings are all formed by air pressure spraying, electrostatic spraying and high-temperature sintering and curing, the service life of the coating is generally only half a year to one year, the coating is low in hardness (the Vickers hardness of the PTFE non-stick coating is 100-200HV, the Vickers hardness of the ceramic non-stick coating is 200-350HV), the coating is small in adhesive force (the binding force of the PTFE non-stick coating is 2-10MPa, the binding force of the ceramic non-stick coating is 2-5MPa), the coating is small in thickness (the thickness of the PTFE non-stick coating is 20-50 mu m, the thickness of the ceramic non-stick coating is 20-40 mu m), and the acid-alkali resistance and salt resistance are common, and the coating can not avoid peeling off caused by scraping, abrasion and corrosion in the long-term use process, And when the surface coating fails, the non-stick coating does not have non-stick property, which causes great limitation to the service life and application of the coating.
The existing cooking appliances, including woks, electric cookers, pressure cooker liners and the like, use non-stick coatings in a large range, and the provision of a durable non-stick coating with excellent performance becomes a key problem in the cooker industry.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide a non-stick coating, a preparation method thereof, a cooker and cooking equipment, wherein the non-stick coating has the advantages of high surface hardness, high coating binding force, good hydrophobic non-stick property and the like.
The inventor of the present invention has conducted extensive research on raw materials and forming methods of a non-stick coating in order to improve the performance of the non-stick coating, and found that, for two materials, namely ceramic powder and fluorine-containing polyester powder, each has advantages, and if the two materials can be combined together to form the non-stick coating, the comprehensive effect of the non-stick coating is expected to be improved, based on this starting point, the inventor has conducted extensive research again, and found that the fluorine-containing polyester material has a low melting point and is easily atomized under heating, and when the fluorine-containing polyester material is atomized, molten droplets of the ceramic particles are made to pass through the atomized substance of the fluorine-containing polyester material, so that the atomized substance of the fluorine-containing polyester material can be attached to the surface of the ceramic particles, and further, the fluorine-containing polyester material can be relatively uniformly distributed on the surface of the ceramic particles even if the amount of the fluorine-containing polyester material is small, so as to improve the functional characteristics of the non-stick coating, such as hydrophobic non-stick property (large wetting angle of the surface of the coating) while maintaining the hardness of the non-stick coating formed by stacking the ceramic particles; meanwhile, the non-stick coating is formed by adopting the special mode of plasma spraying, which is beneficial to greatly improving the bonding strength of the non-stick coating; in addition, the combination of specific equipment and a specific process can simultaneously improve the scratch resistance, the corrosion resistance, the coating compactness (low porosity) and the service life of the non-stick coating.
Accordingly, in order to achieve the above object, the present invention provides, in one aspect, a method for preparing a non-stick coating, the method comprising:
(1) pretreating a substrate;
(2) carrying out optional preheating treatment on the surface of the substrate obtained in the step (1);
(3) taking ceramic powder and fluorine-containing resin powder as raw materials, and forming a non-stick coating on the surface of a substrate through plasma spraying treatment;
wherein, in the step of the plasma spraying treatment, a flame flow formed by a plasma spray gun is adopted, and ceramic powder is fed in the formed flame flow at a distance D1 from an outlet of the spray gun, fluorine-containing resin powder is fed at a distance D2 from the outlet of the spray gun, wherein D2 is larger than D1, and the weight ratio of the powder feeding amount of the fluorine-containing resin powder to the powder feeding amount of the ceramic powder is 0.14-0.3: 1.
in a second aspect, the invention provides a non-stick coating prepared by the method of the invention.
The invention provides a pan, which comprises a base body and a non-stick coating formed on the base body, wherein the non-stick coating comprises ceramic particles and fluorine-containing resin dispersed among the ceramic particles, and the non-stick coating comprises the following components by taking the total weight of the non-stick coating as a reference: 80-95 wt% of ceramic particles and 5-20 wt% of a fluorine-containing polyester material.
In a fourth aspect the invention provides a cooking apparatus comprising a pan according to the invention.
The method for preparing the non-stick coating comprises the steps of feeding ceramic powder and fluorine-containing resin powder at different positions of flame flow formed by a plasma spray gun, so that molten drops of the ceramic particles penetrate through a mist of the fluorine-containing resin material and then impact the surface of a substrate, further forming particles of the fluorine-containing resin material coated ceramic particles, and forming the non-stick coating based on the accumulation of the particles; the non-stick coating formed by the method has the following beneficial effects:
1) although the fluorine-containing resin is added into the formed non-stick coating, the content of the fluorine-containing resin material is less, and the non-stick coating still mainly comprises ceramic particles, so that the formed non-stick coating can more easily show the hardness property of the ceramic particles;
2) in the formed non-stick coating, although the content of the fluorine-containing polyester material is less, the fluorine-containing resin material is relatively uniformly dispersed or coated on the surface of the ceramic particles by a special method, so that the wetting angle of the surface of the formed non-stick coating is enlarged, the hydrophobic non-stick property of the non-stick coating is further improved, the scratch resistance and the corrosion resistance of the non-stick coating are also improved, and the service life of the non-stick coating is further prolonged;
3) in the process of forming the coating by plasma spraying (i.e. the process of accumulating molten particles), all the particles are connected together in a molten state, so that the coating is compact (small in porosity) and the bonding among the particles is very firm (high in bonding force); the non-stick coating and the substrate form mechanical bonding on the rough surface through high-speed molten particles, which is much higher than the bonding strength of the coating formed by sintering after air spraying;
4) the formed non-stick coating is formed by piling up flat particles with basically the same structure, so that the formed non-stick coating has relatively uniform and stable structure from inside to outside, and even when the surface is partially worn in the use process, the inner layer structure is consistent with the surface structure, the hardness, hydrophobic non-stick property, bonding force, scraping resistance and corrosion resistance of the non-stick coating can be still maintained, and the service life of the non-stick coating is prolonged.
Drawings
Fig. 1 is a schematic structural view of the pot of the present invention.
Description of the reference numerals
1 is a non-stick coating and 2 is a substrate.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
In order to improve the surface hardness, coating adhesion, and hydrophobic non-stick properties of the non-stick coating, there is provided in the present invention a method of preparing a non-stick coating, the method comprising: (1) pretreating a substrate; (2) carrying out optional preheating treatment on the surface of the substrate obtained in the step (1); (3) taking ceramic powder and fluorine-containing resin powder as raw materials, and forming a non-stick coating on the surface of a substrate through plasma spraying treatment; wherein, in the step of the plasma spraying treatment, a flame flow formed by a plasma spray gun is adopted, and ceramic powder is fed in the formed flame flow at a distance D1 from an outlet of the spray gun, fluorine-containing resin powder is fed at a distance D2 from the outlet of the spray gun, wherein D2 is larger than D1, and the weight ratio of the powder feeding amount of the fluorine-containing resin powder to the powder feeding amount of the ceramic powder is 0.14-0.3: 1.
according to the method provided by the invention, by controlling the powder feeding amount ratio of the ceramic powder to the fluorine-containing resin powder, the content of the ceramic powder is 95-80 wt% and the content of the fluorine-containing polyester powder is 5-20 wt% of the formed non-stick coating based on the total weight of the ceramic powder and the fluorine-containing polyester powder, so that the content of fluorine-containing resin materials is less and ceramic particles are still the main content in the formed non-stick coating although fluorine-containing resin is added, and the formed non-stick coating can more easily show the specific hardness performance of the ceramic particles; meanwhile, in the formed non-stick coating, although the content of the fluorine-containing polyester material is low, the fluorine-containing resin material is relatively uniformly dispersed on the surface of the ceramic particles by a special method, so that the wetting angle of the surface of the formed non-stick coating is enlarged, the hydrophobic non-stick property of the non-stick coating is further improved, the scratch resistance and the corrosion resistance of the non-stick coating are also favorably improved, and the service life of the non-stick coating is further prolonged.
According to the process of the invention, the flame length is preferably 1/6 ≦ D2-D1 ≦ 1/2 of the flame length, more preferably 1/4 ≦ D2-D1 of the flame length 1/3, wherein the flame length is preferably 14-18 cm.
According to the method of the invention, preferably, in the step of plasma spraying treatment, the spraying power is 30-50kW, and the spraying current is 600-650A; the flow rate of main gas (such as argon) in the working gas is 35-55L/min, and the flow rate of auxiliary gas (such as hydrogen) is 2-6L/min; the D1 is 1/4-1/3 of the flame flow length, and the D2 is 1/2-2/3 of the flame flow length. More preferably, in the step of plasma spraying treatment, the spraying power is 35-45kW, and the spraying current is 620-630A; the flow rate of the main gas in the working gas is 40-50L/min, and the flow rate of the auxiliary gas is 3-5L/min.
Preferably, in the step of plasma spraying treatment, the spraying angle is 70-90 °;
according to the method of the present invention, preferably, in the step of plasma spraying treatment, the spraying distance is 60 to 100mm, preferably 75 to 85 mm; the lance movement speed is 60 to 100mm/s, preferably 75 to 85 mm/s.
According to the method of the present invention, preferably, the powder feeding amount of the ceramic powder is 5 to 7 g/min; the powder feeding amount of the fluorine-containing resin powder is 1-1.5 g/min. In the plasma spraying process, a part of raw material of fluorine-containing resin is lost in the process of atomizing and attaching fluorine-containing resin particles on the surface of the ceramic particle core, and the prepared non-stick coating is measured by a chemical analysis method, and the powder feeding amount is controlled in the above range, so that the prepared non-stick coating comprises the following components by taking the total weight as a reference: 80-95 wt% of ceramic powder and 5-20 wt% of fluorine-containing polyester powder.
According to the process of the invention, the alumina powder preferably has a particle size D50 of 5-80 μm, preferably 20-50 μm, and a flowability of 10-30s/50 g; the particle diameter D50 of the fluorine-containing resin powder is 20-100 μm, preferably 40-100 μm, and more preferably 45-60 μm; the flowability of the fluorine-containing resin powder is less than 30s/50g, preferably 10 to 25s/50g, and more preferably 10 to 20s/50 g. Wherein the particle diameter D50 is the volume average diameter, which refers to the equivalent diameter of the largest particle in the particle size distribution curve with a cumulative distribution of 50 vol%.
According to the method of the present invention, in selecting the fluorine-containing resin powder, if the flowability of the commercially available fluorine-containing resin powder cannot satisfy the requirement, the fluorine-containing resin powder may be modified to obtain a fluorine-containing resin powder having the required flowability, and in a preferred case, the modified fluorine-containing resin powder is prepared by a method comprising the steps of: (a) mixing fluorine-containing resin powder, a binder, a lubricant and water to prepare slurry; (b) and (4) carrying out spray drying treatment on the slurry.
Preferably, in the step (a), the fluorine-containing resin powder is contained in an amount of 30 to 60% by weight, more preferably 38 to 55% by weight, based on the weight of the slurry; the content of the binder is 0.2 to 2% by weight, more preferably 0.2 to 0.5% by weight; the content of the lubricant is 0.5 to 3% by weight, more preferably 1 to 3% by weight; the content of water is 35 to 68% by weight, more preferably 42 to 60% by weight.
Preferably, in the step (a), the binder is at least one of polyvinyl alcohol, polyvinyl chloride and polyacrylate.
Preferably, in step (a), the lubricant is at least one of glycerol, paraffin and graphite.
Preferably, in step (b), the spray drying process is carried out by gas-flow spray drying under the conditions comprising: the atomization pressure is 0.3-0.6MPa, and the optimized pressure is 0.3-0.5 MPa; the flow rate of the atomized air flow is 1-4m3H, more preferably 1 to 3m3H; the inlet temperature is 200-400 ℃, and the more preferable inlet temperature is 300-350 ℃; the temperature of the air outlet is 50-200 ℃, and the preferable temperature is 50-150 ℃.
According to the method of the present invention, preferably, the ceramic powder is alumina and/or titania, preferably a mixture of alumina and titania, more preferably the weight ratio of alumina to titania is 2.5-10: 1.
according to the method of the present invention, preferably, the fluorine-containing resin powder is Polytetrafluoroethylene (PTFE) and/or tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (PFA), and preferably the melting point of the fluorine-containing resin powder is 350-420 ℃, more preferably 400-420 ℃.
According to the method of the present invention, the substrate may be a metal substrate such as a stainless steel substrate, an aluminum alloy substrate, a titanium alloy substrate, or a multi-layer (including two or more layers) metal composite substrate. Wherein, the multi-layer metal composite substrate can be a stainless steel/aluminum substrate, a stainless steel/copper substrate, a stainless steel/aluminum/copper substrate, and the like. Preferably, the thickness of the substrate is 0.5-6 mm.
According to the method of the present invention, the pretreatment method of step (1) may preferably include a sand blasting treatment and a degreasing treatment, and the methods of the sand blasting treatment and the degreasing treatment are not particularly limited and may be various methods commonly used in the art, respectively. For example, the method of blasting includes: adopting sand grains (such as glass sand, brown steel sand, black brown jade, white corundum, carborundum, etc.) with 60-150 meshes, controlling the pressure of the air-jet to be 0.2-0.9MPa, and obtaining the roughness of Ra2-8 μm. After the sandblasting, the residual fine powder particles on the inner surface of the substrate are removed, and the method for removing is not particularly limited, and the residual fine powder particles can be removed by blowing them clean with a high-pressure gas flow or by washing them with water, which are well known to those skilled in the art and will not be described herein. For example, the degreasing treatment may sequentially comprise alkali washing, acid washing, water washing and high-temperature drying (e.g. drying at 200-.
According to the method of the present invention, preferably, in the step (2), the surface of the substrate obtained in the step (1) is preheated to 80 to 150 ℃.
In a second aspect, the invention provides a non-stick coating prepared by the above method.
In a third aspect, as shown in fig. 1, the present invention provides a pot comprising a base 2 and a non-stick coating 1 formed on the base 2, wherein the non-stick coating comprises ceramic particles and fluorine-containing resin dispersed among the ceramic particles, and the non-stick coating comprises, based on the total weight of the non-stick coating: 80-95 wt% of ceramic powder and 5-20 wt% of fluorine-containing polyester powder.
Preferably, the ceramic particles comprise alumina particles and/or titanium oxide particles, preferably a mixture of alumina particles and titanium oxide particles, more preferably the weight ratio of the alumina particles to the titanium oxide particles is 2.5-10: 1.
preferably, the fluorine-containing resin powder is PTFE and/or PFA.
Preferably, said non-stick coating 1 is a non-stick coating according to the invention.
In a fourth aspect, the invention provides a cooking apparatus comprising a pan according to the invention. Preferably, the cooking device is a wok, a frying pan, an air fryer, a frying and baking machine, a bread maker, an electric cooker, an electric pressure cooker or a soybean milk maker.
The non-stick coating of the present invention and its method of preparation are described in detail by way of examples below. In the following examples, unless otherwise specified, each material used was commercially available, and each method used was a method commonly used in the art.
In the following examples, the measurement methods involved are illustrated below:
the particle diameter D50 of the PFA powder was measured by a laser particle size analyzer (available from xiamen kowang electronics ltd., model number KW 510).
The flowability of the PFA powder was determined according to GB1482-84 using a Hall flow meter.
The purity of the PFA powder was determined using an automatic polarimeter (purchased from ITUP China, model number AP-300).
The melting point of the PFA powder was measured using a micro melting point apparatus (available from Atlantic Hainan instruments, Inc., model No. MP-300).
The surface roughness Ra of the PFA powder was measured by a surface roughness meter (model TIME3201, available from Peak technologies, Inc., of Beijing TIME).
The original and post-friction contact angles were measured using a contact angle measuring instrument (model XHSCAZ-2, from Shenzhen, Xinhensen, Inc.) over a range of 0-180 deg..
In the following examples, the starting materials involved are illustrated below:
the alumina powder was purchased from Beijing Yao science and technology development Co., Ltd, and had a particle size D50 of 32 μm and a flowability of 12s/50 g.
The titanium oxide powder was purchased from Beijing Yao science and technology development Co., Ltd, and had a particle size D50 of 38 μm and a flowability of 18s/50 g.
A conventional PFA powder was purchased from Dajin fluorine coating (Shanghai) Co., Ltd., particle diameter D50 was 15 μm, sphericity of 95% powder was 18%, fluidity was 78s/50g, purity was 94%, melting point was 345 ℃ and surface roughness was Ra0.6. mu.m.
Modified PFA powder a1, preparation method comprising: (1) mixing 47.6kg of ordinary PFA powder, 0.4kg of polyvinyl alcohol (available from Shanghai Fusi Chunshiki technology, Inc., model No. PVA1788), 2kg of glycerin and 50kg of water to prepare a slurry; (2) and carrying out airflow atomization drying treatment on the slurry, wherein the airflow atomization drying conditions comprise: the atomization pressure is 0.4MPa, and the atomization airflow flow is 2m3And h, the inlet temperature is 320 ℃, and the outlet temperature is 100 ℃, so that the modified PFA powder A1 is obtained. The modified PFA powder A1 was found to have a particle diameter D50 of 52 μm, a flowability of 15s/50g, a purity of 99.9%, a melting point of 410 ℃ and a surface roughness of Ra0.2. mu.m.
Modified PFA powder a2, preparation method comprising: (1) mixing 54.8kg of ordinary PFA powder, 0.2kg of polyvinyl chloride (purchased from Shanghai Jinning industries, Ltd., type K55-59), 3kg of paraffin wax and 42kg of water to prepare a slurry; (2) and carrying out airflow atomization drying treatment on the slurry, wherein the airflow atomization drying conditions comprise: the atomization pressure is 0.3MPa, and the atomization airflow flow is 1m3And h, the inlet temperature is 300 ℃, and the outlet temperature is 60 ℃, so that the modified PFA powder A2 is obtained. The modified PFA powder was found to have a particle diameter D50 of 46 μm, a flowability of 13s/50g, a purity of 99.5%, a melting point of 405 ℃ and a surface roughness Ra 0.15. mu.m.
Example 1
This example illustrates the preparation of a non-stick coating by plasma spraying.
(1) Pretreating an aluminum pot substrate (with the thickness of 2.5mm), wherein the pretreatment method comprises the following steps: a) deoiling at 55 deg.C for 8 min; b) washing with deionized water; c) oven drying at 100 deg.C for 5 min; d) adopting 60-80 mesh brown steel sand, carrying out sand blasting treatment on the inner surface of the aluminum pot base body under the air jet flow pressure of 0.6MPa to ensure that the surface roughness is Ra3 mu m, and then blowing the residual powder particles on the inner surface of the pot body base body by using air flow (air); e) alkali washing with 40 wt% NaOH solution at 80 deg.C for 1 min; f) neutralizing with 20 wt% nitric acid solution for 3 min; g) washing with deionized water, and drying at 300 deg.C for 12 min;
(2) preheating the surface of the substrate obtained in the step (1) to 120 ℃;
(3) mixing 5: 1 and modified PFA powder A1 as raw materials, and forming a non-stick coating on the surface of a substrate through plasma spraying treatment; wherein, the plasma spraying treatment conditions comprise: the spraying power of the plasma spray gun is 40kW, the spraying current is 625A, the argon flow in the working gas is 45L/min, and the hydrogen flow is 4L/min; the spraying distance of the plasma spray gun from the substrate is 80mm, the spraying angle is 80 degrees +/-1 degree, and the moving speed of the spray gun is 80 mm/s; feeding a mixture of alumina powder and titania powder into a flame stream formed by a plasma torch at a distance D1 (1/4 of the length of the flame stream) from the torch outlet, the powder feeding amount being 6g/min, and feeding modified PFA powder A1 at a distance D2 (1/2 of the length of the flame stream) from the torch outlet, the powder feeding amount being 1.2 g/min; a non-stick coating with a thickness of 200 μm was formed.
Example 2
This example illustrates the preparation of a non-stick coating by plasma spraying.
(1) An aluminum pan substrate (thickness 2.5mm) was pretreated according to the method of example 1;
(2) preheating the surface of the substrate obtained in the step (1) to 100 ℃;
(3) mixing the alumina powder and the titanium oxide powder in a weight ratio of 2.5: 1, and modified PFA powder A2 serving as raw materials are subjected to plasma spraying treatment to form a non-stick coating on the surface of a substrate; wherein, the plasma spraying treatment conditions comprise: the spraying power of the plasma spray gun is 35kW, the spraying current is 620A, the argon flow in the working gas is 40L/min, and the hydrogen flow is 3L/min; the spraying distance of the plasma spray gun from the substrate is 85mm, the spraying angle is 80 degrees +/-1 degree, and the moving speed of the spray gun is 85 mm/s; feeding a mixture of alumina powder and titania powder into a flame stream formed by a plasma torch at a distance D1 (1/3 of the length of the flame stream) from the torch outlet, the powder feeding amount being 5g/min, and feeding modified PFA powder A2 at a distance D2 (1/3 of the length of the flame stream) from the torch outlet, the powder feeding amount being 1.5 g/min; a non-stick coating with a thickness of 200 μm was formed.
Example 3
This example illustrates the preparation of a non-stick coating by plasma spraying.
(1) An aluminum pan substrate (thickness 2.5mm) was pretreated according to the method of example 1;
(2) preheating the surface of the substrate obtained in the step (1) to 150 ℃;
(3) mixing 10 of alumina powder and titanium oxide powder in a weight ratio: 1, and modified PFA powder A1 serving as raw materials are subjected to plasma spraying treatment to form a non-stick coating on the surface of a substrate; wherein, the plasma spraying treatment conditions comprise: the spraying power of the plasma spray gun is 45kW, the spraying current is 630A, the argon flow in the working gas is 50L/min, and the hydrogen flow is 5L/min; the spraying distance of the plasma spray gun from the substrate is 75mm, the spraying angle is 80 degrees +/-1 degree, and the moving speed of the spray gun is 75 mm/s; feeding a mixture of alumina powder and titania powder into a flame stream formed by a plasma torch at a distance D1 (1/4 of the length of the flame stream) from the torch outlet, the powder feeding amount being 7g/min, and feeding modified PFA powder A1 at a distance D2 (1/2 of the length of the flame stream) from the torch outlet, the powder feeding amount being 1 g/min; a non-stick coating with a thickness of 200 μm was formed.
Example 4
The process of example 1 was followed except that in step (3), alumina powder was fed into the flame stream formed by the plasma torch at a distance D1 (1/4 of the length of the flame stream) from the torch outlet, and modified PFA powder A1 was fed at a distance D2 (2/3 of the length of the flame stream); a non-stick coating with a thickness of 200 μm was formed.
Example 5
The process of example 1 was followed except that in step (3), alumina powder was fed into the flame stream formed by the plasma torch at a distance D1 (flame stream length 1/3) from the torch outlet, and modified PFA powder A1 was fed at a distance D2 (flame stream length 1/2) from the torch outlet; a non-stick coating with a thickness of 200 μm was formed.
Example 6
The process of example 1 was followed except that in step (3), alumina powder was fed into the flame stream formed by the plasma torch at a distance D1 (1/4 of the length of the flame stream) from the torch outlet, and modified PFA powder A1 was fed at a distance D2 (5/6 of the length of the flame stream); a non-stick coating with a thickness of 200 μm was formed.
Example 7
The method according to example 1 except that in the step (3), alumina powder of the same powder feeding amount was used in place of the mixture of alumina powder and titania powder; a non-stick coating with a thickness of 200 μm was formed.
Example 8
The process of example 1 was followed except that, in step (3), the plasma spray gun was operated at a spray power of 30kW, a spray current of 600A, an argon gas flow rate of 35L/min and a hydrogen gas flow rate of 2L/min in the working gas, to form a non-stick coating having a thickness of 200. mu.m.
Example 9
The process of example 1 was followed except that, in step (3), the plasma spray gun was set to spray a power of 50kW, a spray current of 650A, an argon gas flow rate of 55L/min in the working gas and a hydrogen gas flow rate of 6L/min, to form a non-stick coating having a thickness of 200. mu.m.
Comparative example 1
The procedure of example 1 was followed except that in step (3), the modified PFA powder A1 was not added to form a non-stick coating having a thickness of 200 μm.
Comparative example 2
The process of example 1 was followed except that the non-stick coating was formed in steps (3) to (4) by: an electrostatic spray treatment was performed using a conventional PFA powder (ACX-33 powder commercially available from macropoly PFA) to form a PFA non-stick coating D1 on the surface of the substrate, wherein the conditions of the electrostatic spray treatment included: powder spraying is carried out by adopting an electrostatic spray gun, the voltage is 35kV, the electrostatic current is 15 muA, the flow velocity pressure is 0.45MPa, the atomization pressure is 0.4MPa, the thickness of the sprayed coating is 40μm, after the spraying is finished, the sprayed coating is dried in an infrared furnace, the dried coating is dried at the low temperature of 120 ℃ for 10min, and the heat is preserved at the high temperature of 400 ℃ for 20 min.
Comparative example 3
Spraying a PTFE non-stick coating by adopting an air pressure spraying mode, wherein the coating comprises a bottom layer and a surface layer; the base oil comprises fluororesin, a binder, pigment and an auxiliary agent, and the surface oil comprises fluororesin, wear-resistant particles and a film-forming auxiliary agent. The method comprises the following specific steps:
(1) pretreating an aluminum pot substrate according to the step (1) of the embodiment 1;
(2) preheating the surface of the matrix obtained in the step (1) to 85 ℃;
(3) spraying base oil: spraying pressure of 0.3MPa, spraying angle of 70 degrees, spraying distance of 30cm, film thickness of 20 μm, drying temperature of 130 deg.C, and keeping temperature for 12 min;
(4) surface oil spraying: the spraying pressure is 0.4MPa, the spraying angle is 70 degrees, the spraying distance is 35 mu m, the film thickness is 30 mu m, the drying and curing temperature is 420 ℃, and the temperature is kept for 15 min.
Comparative example 4
Spraying a ceramic non-stick coating by adopting an air pressure spraying mode, wherein the coating comprises a bottom layer and a surface layer; the base oil comprises a binder, a pigment and an auxiliary agent, and the surface oil comprises silicon oxide and aluminum oxide. The method comprises the following specific steps:
(1) pretreating an aluminum pot substrate according to the step (1) of the embodiment 1;
(2) preheating the surface of the substrate obtained in the step (1) to 60 ℃;
(3) spraying base oil: spraying pressure of 0.3MPa, spraying angle of 70 degrees, spraying distance of 25cm, film thickness of 25 μm, pre-drying temperature of 70 deg.C, and keeping temperature for 10 min;
(4) surface oil spraying: the spraying pressure is 0.3MPa, the spraying distance is 25cm, the spraying angle is 70 degrees, the thickness of the film layer is 10 microns, the 280 ℃ sintering is carried out after the spraying is finished, and the temperature is kept for 15 min.
Test examples
1. Coating surface hardness: the Vickers hardness of each coating was measured according to GB/T9790-1988 using a Vickers hardness tester (model HX-1000 available from Shanghai rectangular optics, Inc.). The results are shown in Table 1.
2. Coating binding force: the coating cohesion is determined according to G98642-88. The results are shown in Table 1.
3. Porosity of the coating: and (3) determining the porosity of the coating according to the mechanical industry standard JB/T7509-94 of the people's republic of China. The results are shown in Table 1.
4. Coating spraying efficiency: according to the formula: the spraying efficiency was calculated as (weight of workpiece after spraying-weight of workpiece before spraying)/(powder feeding amount-deposition rate), wherein the deposition rate was fixed at 70%. The calculation results are shown in Table 1.
5. Scratch resistance of the coating: washing water with the concentration of 5 weight percent and 3M (7447C) scouring pad with the load of 2.5kgf are prepared by using the scouring liquid, the left-right swinging is carried out for 1 time, the scouring pad is replaced every 250 times, whether the coating falls off or the base material is exposed after each scraping is checked (the test is ended by exposing more than or equal to 10 lines), and the abrasion resistance times are recorded. The results are shown in Table 1.
6. Acid, alkali and salt resistance:
acid resistance: adding an acetic acid solution with the concentration of 5 weight percent into the inner pot until the position of the maximum scale water level of the inner wall of the inner pot, putting the inner pot into the corresponding pot, continuously heating and boiling (keeping the boiling state) for 10 minutes by electrifying the closing cover, then preserving heat and soaking for 24 hours at 100 ℃, cleaning the inner pot after the test is finished, and visually checking the change condition of the surface of the coating, wherein the result is shown in table 2.
Alkali resistance: adding 0.5 wt% sodium hydroxide solution into the inner pot until the inner wall of the inner pot reaches the maximum scale water level, putting the inner pot into the corresponding pot, continuously heating and boiling (keeping the boiling state) for 10 minutes by electrifying the closing cover, then preserving heat and soaking for 24 hours at 100 ℃, cleaning the inner pot after the test is finished, and visually checking the change condition of the coating surface, wherein the result is shown in table 2.
Salt tolerance: adding a sodium chloride solution with the concentration of 5 weight percent into the inner pot until the position of the maximum scale water level of the inner wall of the inner pot, putting the inner pot into a corresponding pot, electrifying and closing the cover, continuously heating and boiling for 8 hours (replenishing water for 1 time every 2 hours, keeping the liquid level at the position of the beginning of the test), keeping the temperature at 80 ℃ for 16 hours to form a period, visually checking the change condition of the surface of the coating after the test of each period, and recording the period number of the coating with the undesirable phenomena of foaming, salient points and the like, wherein the results are shown in Table 2.
7. Abrasion resistance and wettability: a frictional wear test was performed according to GB/T1768-79(89), the contact angles (original contact angle and contact angle after friction, respectively) before and after the frictional wear test were measured and weighed, and the weight loss ratio was calculated according to the formula, where the weight loss ratio is (weight before friction-weight after friction)/weight before friction, and the results are shown in table 3. Wherein, the test result shows that: the non-stick coating still has good wettability after the surface is abraded, the wettability of the non-stick coating is kept good as long as a substrate is not exposed, and friction abrasion tests are carried out on three samples of a PTFE non-stick coating, a ceramic non-stick coating and the non-stick coating, so that the following results can be found: the non-stick coating of the invention only partially falls off in powder form in the friction and wear process, the use performance is not affected, and the PTFE non-stick coating and the ceramic non-stick coating both fall off between flaky layers, so the difference is large.
TABLE 1
TABLE 2
| Acid resistance | Alkali resistance | Salt tolerance | |
| Example 1 | No whitening and foaming | No whitening and foaming | 20 period |
| Example 2 | No whitening and foaming | No whitening and foaming | 20 period |
| Example 3 | No whitening and foaming | No whitening and foaming | 20 period |
| Example 4 | No whitening and foaming | No whitening and foaming | 20 period |
| Example 5 | No whitening and foaming | No whitening and foaming | 18 cycles |
| Example 6 | No whitening and foaming | No whitening and foaming | 20 period |
| Example 7 | No whitening and foaming | No whitening and foaming | 20 period |
| Example 8 | No whitening and foaming | No whitening and foaming | 12 period |
| Example 9 | No whitening and foaming | No whitening and foaming | 20 period |
| Comparative example 1 | No whitening and foaming | No whitening and foaming | 10 cycles |
| Comparative example 2 | No whitening and foaming | No whitening and foaming | 6 cycles |
| Comparative example 3 | No whitening and foaming | No whitening and foaming | 4 period |
| Comparative example 4 | No whitening and foaming | No whitening and foaming | 2 period |
TABLE 3
| Number of rubs | Loss ratio (%) | Original contact Angle (°) | Contact Angle after Friction (°) | |
| Example 1 | 1000 | 1.1 | 104 | 101 |
| Example 1 | 2000 | 2.0 | 104 | 98 |
| Example 1 | 3000 | 2.9 | 104 | 95 |
| Example 2 | 1000 | 1.5 | 108 | 104 |
| Example 3 | 1000 | 1.0 | 99 | 95 |
| Example 4 | 1000 | 1.3 | 108 | 103 |
| Example 5 | 1000 | 1.2 | 98 | 92 |
| Example 6 | 1000 | 1.6 | 111 | 105 |
| Example 7 | 1000 | 1.3 | 102 | 98 |
| Example 8 | 1000 | 2.6 | 105 | 100 |
| Example 9 | 1000 | 0.9 | 96 | 91 |
| Comparative example 1 | 1000 | 0.8 | 20 | 20 |
| Comparative example 2 | 1000 | 6.0 | 125 | 90 |
| Comparative example 3 | 1000 | 8.9 | 121 | 87 |
| Comparative example 4 | 1000 | 4.8 | 110 | 78 |
As can be seen from the results in tables 1-3, in the method for preparing the non-stick coating by using the plasma spraying technology, the mixture of the PFA powder and the ceramic powder can be used for spraying a layer of non-stick coating on the surface of the substrate, so that the non-stick coating with excellent performance can be obtained, and the obtained non-stick coating has the advantages of high surface hardness, high coating binding force, good scratch resistance, good corrosion resistance, good wettability, long service life and the like.
Wherein, comparing the results of example 1 with examples 4-6, it can be seen that the surface hardness and wettability of the non-stick coating can be optimized comprehensively by adding the ceramic powder and the fluorine-containing resin powder in a specific interval (i.e., 1/6-D2-D1-1/2 of flame length, preferably 1/4-D2-D1 of flame length-1/3).
In particular, comparing the results of example 1 and example 7, it can be seen that the use of a mixture of alumina and titania (particularly a mixture in a weight ratio of 2.5 to 10: 1) as the ceramic powder contributes to further increasing the surface hardness of the non-stick coating.
Wherein, comparing the results of the embodiment 1 and the embodiments 8-9, it can be known that under the specific plasma spraying treatment conditions (i.e. the spraying power is 35-45kW, the spraying current is 620-630A; the flow rate of the main gas in the working gas is 40-50L/min, and the flow rate of the auxiliary gas is 3-5L/min), the surface hardness, the coating bonding force, the scratch resistance, the corrosion resistance, the wettability and the service life of the non-stick coating can be further improved.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (19)
1. A method of making a non-stick coating, comprising:
(1) pretreating a substrate;
(2) carrying out optional preheating treatment on the surface of the substrate obtained in the step (1);
(3) taking ceramic powder and fluorine-containing resin powder as raw materials, and forming a non-stick coating on the surface of a substrate through plasma spraying treatment;
wherein, in the step of the plasma spraying treatment, a flame flow formed by a plasma spray gun is adopted, and ceramic powder is fed in the formed flame flow at a distance D1 from an outlet of the spray gun, fluorine-containing resin powder is fed at a distance D2 from the outlet of the spray gun, wherein D2 is larger than D1, and the weight ratio of the powder feeding amount of the fluorine-containing resin powder to the powder feeding amount of the ceramic powder is 0.14-0.3: 1;
1/4-D2-D1-1/3 of the flame flow length,
the flowability of the fluorine-containing resin powder is less than 30s/50 g.
2. The method as claimed in claim 1, wherein in the step of plasma spraying treatment, the spraying power is 30-50kW, and the spraying current is 600-; the flow rate of main gas in the working gas is 35-55L/min, and the flow rate of auxiliary gas is 2-6L/min; the D1 is 1/4-1/3 of the flame flow length, and the D2 is 1/2-2/3 of the flame flow length.
3. The method as claimed in claim 2, wherein in the step of plasma spraying treatment, the spraying power is 35-45kW, and the spraying current is 630A; the flow rate of main gas in the working gas is 40-50L/min, and the flow rate of auxiliary gas is 3-5L/min.
4. The method according to claim 1, wherein in the step of plasma spray-treating, the spray distance is 60-100 mm; the moving speed of the spray gun is 60-100 mm/s.
5. The method according to claim 4, wherein in the step of plasma spray-treating, the spray distance is 75-85 mm; the moving speed of the spray gun is 75-85 mm/s.
6. The method according to claim 1, wherein the fluorine-containing resin powder has a particle size D50 of 20 to 100 μm.
7. The method according to claim 6, wherein the fluorine-containing resin powder has a particle size D50 of 40 to 100 μm; the flowability of the fluorine-containing resin powder is 10-25s/50 g.
8. The method according to claim 7, wherein the fluorine-containing resin powder has a particle size D50 of 45 to 60 μm; the flowability of the fluorine-containing resin powder is 10-20s/50 g.
9. The method according to any one of claims 1 to 8, wherein the ceramic powder is fed in an amount of 5 to 7 g/min; the powder feeding amount of the fluorine-containing resin powder is 1-1.5 g/min.
10. The method according to any one of claims 1 to 8, wherein the surface of the substrate obtained in step (1) is preheated to 80 to 150 ℃ in step (2).
11. The method according to any one of claims 1 to 8, wherein the ceramic powder is alumina and/or titania and the fluorine-containing resin powder is PTFE and/or PFA.
12. The method of claim 11, wherein the ceramic powder is a mixture of alumina and titania.
13. The method as claimed in claim 12, wherein the alumina powder has a particle size D50 of 5-80 μm and a flowability of 10-30s/50 g.
14. The method of claim 13, wherein the alumina powder has a particle size D50 of 20-50 μ ι η.
15. The method of claim 12, wherein the weight ratio of alumina to titania is from 2.5-10: 1.
16. a non-stick coating prepared by the method of any one of claims 1 to 15.
17. A cookware, characterized in that it comprises a base (2) and a non-stick coating (1) formed on the base (2), wherein said non-stick coating is a non-stick coating obtained by a method according to any one of claims 1 to 15.
18. A cooking appliance, characterized in that it comprises a pot according to claim 17.
19. The cooking device of claim 18, wherein the cooking device is a wok, a frying pan, an air fryer, a toaster, an electric cooker, an electric pressure cooker, or a soymilk maker.
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| KR1020180046009A KR102090639B1 (en) | 2017-04-25 | 2018-04-20 | Cookware and cooking equipment |
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| US4386112A (en) * | 1981-11-02 | 1983-05-31 | United Technologies Corporation | Co-spray abrasive coating |
| US4696855A (en) * | 1986-04-28 | 1987-09-29 | United Technologies Corporation | Multiple port plasma spray apparatus and method for providing sprayed abradable coatings |
| US6123999A (en) * | 1997-03-21 | 2000-09-26 | E. I. Du Pont De Nemours And Company | Wear resistant non-stick resin coated substrates |
| CN101280405B (en) * | 2008-04-30 | 2011-12-14 | 中国科学院上海硅酸盐研究所 | Lanthanum oxide-aluminum oxide composite coating prepared by plasma spraying method |
| CN105801178A (en) * | 2014-12-29 | 2016-07-27 | 佛山市顺德区美的电热电器制造有限公司 | Ceramic inner pot and preparation method thereof |
| CN104962144B (en) * | 2015-06-10 | 2017-12-01 | 李吉学 | A kind of high-temperature wearable non-sticking lining material and preparation method thereof |
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