Non-stick coating for non-stick pans and method for making same

Abstract

The present application relates to a kind of non-stick pot anti-sticking coating and its preparation method, anti-sticking coating includes the surface of metal pot matrix (1) chromium transition layer (2) and chromium oxide layer (3) on chromium transition layer (2);Chromium transition layer (2) oxygen content is 0.1~2at.%, the rest is chromium;Chromium oxide layer (3) chromium content is 40~50at.%, oxygen content is 25~35at.%, the rest is nitrogen;Preparation by radio frequency reaction magnetron sputtering method deposition, obtain chromium / chromium oxynitride coating;Method includes metal pot matrix (1) pretreatment, environment preparation, metal pot matrix (1) ion etching cleaning, chromium transition layer (2) deposition and chromium oxynitride layer (3) deposition.Compared with prior art, the present application not only has good corrosion resistance, wear resistance, not easy to decompose at high temperature, temperature resistance can reach 600 DEG C, and coating has excellent non-stick performance, meet the long-term safe use requirements of non-stick pot coating.

Description

Technical Field

[0001] This invention belongs to the field of surface modification and coating materials technology, and relates to an anti-stick coating for non-stick pans and its preparation method. Background Technology

[0002] As people's living standards improve, their demands for various cookware are also increasing. Non-stick pans, as common kitchen utensils, play an important role in the preparation of many dishes. However, the non-stick pans currently on the market do not fully meet people's needs. Currently, the non-stick pan market faces issues regarding the safety and anti-adhesion properties of coating materials, significantly impacting its development. Most non-stick pans used in daily life employ substrate coating technology. If the temperature is raised above 300℃, some non-stick materials will decompose, generating gases harmful to the human body. Other non-stick materials will fail at high temperatures, losing their anti-adhesion properties. Therefore, finding a suitable non-stick coating material to solve these problems is an important application of coating technology in practical life.

[0003] Patent CN114875271A discloses a non-stick coating, its application, and a preparation method thereof. The non-stick coating comprises the following layers connected in sequence: a titanium layer, a titanium-silicon layer, and a titanium-silicon-copper-iron-zinc layer connected to a substrate; the titanium-silicon layer contains 0.1-20 at.% silicon, with the remainder being titanium; the titanium-silicon-copper-iron-zinc layer contains 0.1-5 at.% copper, 0.1-5 at.% iron, 0.1-5 at.% silicon, and 0.1-5 at.% zinc, with the remainder being titanium. Although this patent employs a multi-titanium-based coating structure design, improving the corrosion and wear resistance of non-stick pans, the anti-adhesion ability of this non-stick coating is not high.

[0004] Patent CN1851038A discloses a method for preparing a chromium oxide composite coating. It proposes using an unbalanced radio frequency reactive magnetron sputtering system and chromium, which has strong corrosion resistance and high hardness in its oxide form. A single chromium metal target is used to prepare the composite coating. During preparation, chromium metal is first sputtered as a transition layer, then oxygen is introduced, and the oxygen flow rate and sputtering power are continuously adjusted. When the oxygen flow rate reaches its maximum value, a DC negative bias is applied. While this patent uses unbalanced radio frequency reactive magnetron sputtering to prepare the chromium oxide composite coating, the high oxygen content due to the use of oxygen as the reactant gas, coupled with the fact that the coating's main component is chromium oxide, results in low hardness and thermal stability. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one defect of the existing non-stick pan coating, such as easy peeling, poor thermal stability, and generation of harmful gases when heated, and to provide a non-stick pan coating and its preparation method. This invention not only has good corrosion resistance and wear resistance, and is not easily decomposed at high temperatures, but its temperature resistance can reach 600℃. Moreover, the coating has excellent non-stick properties, meeting the requirements for long-term safe use of non-stick pan coatings.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a non-stick coating for a non-stick pan, the non-stick coating comprising a chromium transition layer on the surface of a metal pan substrate and chromium oxynitride (CrO) on the chromium transition layer. x N y )layer;

[0008] The oxygen content of the chromium transition layer is 0.1-2 at.%, with the remainder being chromium, wherein the oxygen element comes from the residual oxygen in the furnace cavity;

[0009] The chromium oxide layer has a chromium content of 40-50 at.%, an oxygen content of 25-35 at.%, and the remainder is nitrogen;

[0010] High-hardness, high-corrosion-resistant, and high-anti-stickiness chromium / chromium oxynitride (Cr / CrO) was prepared by radio frequency reactive magnetron sputtering deposition. x N y )coating.

[0011] Chromium oxynitride coatings are widely used in cutting tools, molds, and other fields as surface protective materials to extend the service life of workpieces due to their excellent properties such as high hardness, corrosion resistance, oxidation resistance, thermal stability, bonding strength, and low coefficient of friction. Tools coated with this material exhibit good anti-adhesion properties during cutting, preventing chips from sticking together. Furthermore, the dense chromium trioxide (Cr2O3) oxide layer formed by the coating prevents the release of nitrogen atoms at elevated temperatures, giving the coating excellent high-temperature resistance, meeting the requirements for non-stick cookware coatings.

[0012] Furthermore, the chromium oxynitride layer comprises chromium oxide and nitride in a mass ratio of 2:(4-5).

[0013] Furthermore, the total thickness of the anti-stick coating is 8.2–9.5 μm.

[0014] Furthermore, the thickness of the chromium transition layer is 0.1–0.3 μm, and the thickness of the chromium oxynitride layer is 7.9–9.2 μm.

[0015] One of the technical solutions of the present invention is to provide a method for preparing a non-stick coating for a non-stick pan, the method comprising the following steps:

[0016] (1) Pretreatment of metal pot substrate: The metal pot substrate is roughened, then cleaned and dried;

[0017] (2) Environmental preparation: Place the metal pot base in the vacuum chamber and heat it up to make the temperature of the metal pot base uniform.

[0018] (3) Ion etching cleaning of metal pot substrate: A constant flow of ionized gas is introduced to bombard the metal pot substrate and remove the oxide scale on the surface of the metal pot substrate.

[0019] (4) Chromium transition layer deposition: Open the Cr target and perform deposition;

[0020] (5) Deposition of chromium oxide layer: Introduce reaction gas, turn on Cr2O3 target, and carry out deposition.

[0021] Furthermore, in step (1), the roughness of the roughened surface is 0.2–5.6 μm, the cleaning solution is water or ethanol, and the drying gas is nitrogen or dry air.

[0022] Furthermore, the vacuum chamber pressure in step (2) is 1.4 × 10⁻⁶. -4 ~1.5×10 -4 Pa, temperature is 380~400℃.

[0023] Furthermore, in step (3), the ionizing gas is argon or krypton, with a flow rate of 50-60 sccm and a vacuum degree of 0.2-0.4 Pa;

[0024] The substrate bias voltage is -750 to -700V, the ion ionization voltage is 900 to 1200V, and the bombardment time is 5 to 10 minutes.

[0025] Furthermore, the temperature in step (4) is 420–430°C;

[0026] The Cr target power is 100-110W, the deposition bias voltage is -25 to -20V, and the time is 20-25min.

[0027] Furthermore, in step (5), the temperature is 420–430°C, the reaction gas is nitrogen, the flow rate is 80–90 sccm, and the vacuum degree is 0.5–0.7 Pa;

[0028] The Cr2O3 target power is 120-125W, the deposition bias voltage is -25--20V, and the deposition time is 6-6.2h.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] (1) The non-stick coating of the present invention for non-stick pans is made of Cr / CrO x N y The coating has a strong bond with the substrate and exhibits high hardness, wear resistance, and anti-adhesion properties.

[0031] (2) The present invention uses transition metal nitrides as coatings. The coatings have high temperature resistance, with a heat resistance temperature of up to 600°C. They can work continuously in high-temperature environments and have excellent service life.

[0032] (3) This invention does not contain organic components such as polytetrafluoroethylene, and will not decompose into harmful gases at high temperatures, thus having high safety.

[0033] (4) The present invention uses transition metal oxides as coatings, and the coatings have high corrosion resistance. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the non-stick coating structure of the non-stick pan in an embodiment of the present invention.

[0035] Explanation of markings in the diagram:

[0036] 1—Metal pot substrate, 2—Chromium transition layer, 3—Chromium oxynitride layer. Detailed Implementation

[0037] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0038] Unless otherwise specified, the equipment used in the following embodiments is conventional equipment in the art; unless otherwise specified, the reagents used are commercially available products or prepared by conventional methods in the art. In the following embodiments, unless otherwise described in detail, conventional experimental methods in the art can be used.

[0039] Example:

[0040] A non-stick coating for pans, such as Figure 1 As shown, it includes a chromium transition layer 2 on the surface of the stainless steel metal pot substrate 1 and chromium oxynitride (CrO) on the chromium transition layer 2. x N y Layer 3 was prepared by radio frequency reactive magnetron sputtering to obtain a high-hardness, high-corrosion-resistant, and high-anti-sticking chromium / chromium oxynitride (Cr / CrO) layer. x N yThe coating consists of a chromium transition layer 2 with an oxygen content of 1 at.%, the remainder being chromium, and a chromium oxynitride layer 3 with a chromium content of 45 at.%, an oxygen content of 30 at.%, and the remainder being nitrogen. The chromium oxynitride layer 3 comprises chromium oxides and nitrides in a mass ratio of 2:4.5. The thickness of the chromium transition layer 2 is 0.2 μm, the thickness of the chromium oxynitride layer 3 is 8.3 μm, and the total thickness of the anti-stick coating is 8.5 μm.

[0041] A method for preparing a non-stick coating for a non-stick pan, the specific steps of which are as follows:

[0042] (1) Pretreatment of metal pot substrate 1: The metal pot substrate 1 is roughened to achieve a surface roughness of 3.5 μm, then cleaned with plasma water, and dried with nitrogen (purity of 99.95%).

[0043] (2) Environmental preparation: Place the metal pot base 1 into the vacuum chamber and evacuate the vacuum chamber to 1.5 × 10⁻⁶. -4 Pa, the temperature rises to 400℃, so that the temperature of the metal pot base 1 is uniform throughout;

[0044] (3) Ion etching cleaning of metal pot substrate 1: Argon gas (purity 99.95%) with a constant flow rate of 50 sccm is introduced, the vacuum degree is 0.2 Pa, the substrate bias voltage is -700 V, and the metal pot substrate 1 is bombarded for 5 min at argon ion ionization voltages of 900 V, 1100 V, and 1200 V respectively to remove the oxide scale on the surface of the metal pot substrate 1.

[0045] (4) Deposition of chromium transition layer 2: The temperature in the deposition chamber is 420℃, the Cr target (purity is 99.99%) is turned on, the power of the Cr target is 100W, the deposition bias voltage is -20V, and the time is 20min.

[0046] (5) Deposition of chromium oxide layer 3: The temperature in the deposition chamber is 420℃, nitrogen gas (purity is 99.95%) is introduced, the flow rate is 80sccm, the vacuum degree is 0.5Pa, the Cr2O3 target (purity is 99.99%) is turned on, the power of the Cr2O3 target is 120W, the deposition is carried out, the deposition bias voltage is -20V, and the time is 6h.

[0047] The hardness test of the non-stick coating of a non-stick pan is conducted using the following steps:

[0048] The hardness of the anti-stick coating was measured using a nanoindenter (MTS-Nano Indenter II). A continuous stiffness test was conducted. Five points were randomly selected on the surface of the anti-stick coating sample. A constant pressure was applied and held for a certain time before being released. The average hardness was then calculated. The indentation load was set to 15 mN, the thermal drift rate to 0.05 nm / s, and the load holding time to 5 s. Five measurements were taken, and the arithmetic mean was calculated. The results are shown in Table 1. The final measured average hardness of the anti-stick coating was 22.53 GPa, indicating that the anti-stick coating possesses high hardness.

[0049] Table 1 Hardness of the Examples

[0050] Test location 1 2 3 4 5 Hardness / GPa 23.12 21.21 25.36 21.12 21.84

[0051] The wear resistance test of the non-stick coating of a non-stick pan is conducted using the following steps:

[0052] The test method for the wear resistance of the anti-stick coating is GB1768-1979. A 250g weight was used to polish the anti-stick coating sample for 200 revolutions. The mass loss of the anti-stick coating was measured and used as the wear resistance value. Three tests were conducted, and the average value was taken to avoid errors. The results are shown in Table 2. The final measured average mass loss of the anti-stick coating was 0.0012g, indicating that the anti-stick coating has good wear resistance.

[0053] Table 2 Loss Quality in Examples

[0054] Number of tests 1 2 3 Loss of mass / g 0.0011 0.0013 0.0012

[0055] The specific steps for testing the film-substrate adhesion of an anti-stick coating for a non-stick pan are as follows:

[0056] The film-substrate adhesion of the anti-stick coating was measured using the scratch method. The anti-stick coating sample was fixed, and a scratching needle with a smooth conical tip was used to scratch the surface of the anti-stick coating, perpendicular to the surface. Pressure was gradually increased on the scratching needle at a rate of 20 N / min, with a maximum pressure of 100 N and a sliding distance of 4 mm, until cracks appeared in the anti-stick coating. The minimum force applied at this point was the film-substrate adhesion of the anti-stick coating. Three tests were performed, and the average value was taken to avoid errors. The results are shown in Table 3. The final measured average film-substrate adhesion of the anti-stick coating was 84 N, indicating a strong bond between the anti-stick coating and the substrate, making it difficult to peel off.

[0057] Table 3. Membrane-substrate bonding strength in the examples

[0058] Number of tests 1 2 3 bonding force / N 85 82 85

[0059] The temperature resistance test of the non-stick coating of a non-stick pan is conducted using the following steps:

[0060] The anti-stick coating samples were placed in a muffle furnace for damage temperature testing. First, the anti-stick coating was placed in a muffle furnace in an atmospheric environment. Then, the temperatures were set to 550℃, 600℃, and 650℃ for 15 hours. After heat treatment, the samples were removed and the damage and oxidation of the anti-stick coating were observed. This temperature was used as the anti-stick coating's withstand temperature. The results are shown in Table 4. Multiple measurements showed that the anti-stick coating's withstand temperature was 600℃, indicating that the anti-stick coating has high high-temperature resistance.

[0061] Table 4 Breakage Temperature of Examples

[0062] Number of tests 1 2 3 Damage temperature / ℃ 550 (Undamaged) 600 (damaged) 650 (damaged)

[0063] The high-temperature working time test of the non-stick coating of a non-stick pan is conducted, and the specific steps are as follows:

[0064] The anti-stick coating sample was heat-treated at 500℃ in an atmospheric environment. The time until the hydrophobic properties of the anti-stick coating failed was recorded, and this time was taken as the continuous working time of the anti-stick coating at 500℃. The average value of three tests was taken to avoid errors. The results are shown in Table 5. Finally, the average continuous working time of the anti-stick coating at 500℃ was measured to be 69 hours, indicating that the anti-stick coating has high high-temperature resistance.

[0065] Table 5. Continuous working time at high temperature in the embodiments

[0066] Number of tests 1 2 3 Time / h 69 70 68

[0067] The Cr / CrO in this embodiment x N y The coating can operate continuously for over 60 hours in high-temperature environments, thus avoiding damage under conditions such as dry burning or overheating, and exhibiting excellent service life. Furthermore, Cr / CrO... x N y The coating does not contain organic components such as polytetrafluoroethylene and will not decompose into harmful gases at temperatures above 300°C, thus exhibiting high safety.

[0068] The specific steps for testing the chromium nitride / chromium oxide content of the chromium nitride / chromium oxide layer in the non-stick coating of a non-stick pan are as follows:

[0069] The mass content of chromium oxide and chromium nitride in the chromium nitride layer was analyzed using EPMA (Electron Probe Meta-Analysis). An EOM810Q electron probe microanalyzer was used to test the chromium nitride layer; the electron beam accelerating voltage was 20 kV, and the beam diameter was [missing information]. The mass ratio of chromium nitride to chromium oxide in the chromium nitride layer is shown in Table 6, with an average value of 0.448.

[0070] Table 6 shows the ratio of chromium nitride to chromium oxide mass content in the chromium nitride layer of the examples.

[0071] Number of tests 1 2 3 Chromium oxide: Chromium nitride 1:2 4:9 2:5

[0072] The Cr / CrO in this embodiment x N y The coating contains chromium oxide and nitride in a mass ratio of 2:4.5. The high hardness and high melting point of chromium nitride give the coating high hardness and good thermal stability, while the presence of chromium oxide gives the coating good corrosion resistance.

[0073] Comparative Example 1:

[0074] I bought the 304 stainless steel pot directly.

[0075] Comparative Example 2:

[0076] The aluminum alloy pot was purchased directly.

[0077] The specific steps for testing the corrosion resistance of a metal pot are as follows:

[0078] Tafel curve tests were performed on Comparative Examples 1 and 2 and the Examples using a 3.5 wt.% sodium chloride (NaCl) solution. The self-corrosion potentials obtained are shown in Table 7.

[0079] Table 7 Self-corrosion potentials of Comparative Examples 1 and 2 and Examples

[0080]

[0081] A higher self-corrosion potential in the Tafel curve results indicates better corrosion resistance. The results in the table show that the Cr / CrO ratio in this embodiment... x N y The self-corrosion potential of coated non-stick pans is significantly higher than that of the other two. A comparison of 304 stainless steel pans and aluminum alloy pans illustrates that, relative to the uncoated pan substrate, the Cr / CrO ratio... x N y The coating has good corrosion resistance.

[0082] The hydrophobic properties of the non-stick coating on a non-stick pan were tested, and the specific steps are as follows:

[0083] The hydrophobic angle and roll-off angle were measured using a contact angle meter (DSA-100). Hydrophobic angle measurement: A 5 μL drop of water was placed on the surface of the anti-stick coating sample at a random location. After standing for 1 minute, the contact angle was measured using the contact angle meter, and the average value was taken to reduce the influence of error. Roll-off angle measurement: A 5 μL drop of water was placed on the surface of the anti-stick coating sample at a random location. The stage containing the anti-stick coating was tilted until the water droplet rolled. The roll-off angle was measured, and the average value was taken to reduce the influence of error. Five measurements were taken, and the arithmetic mean was used. The results are shown in Table 8. The final measured average hydrophobic angle of the anti-stick coating was 132°, and the average roll-off angle was 10°.

[0084] Table 8 shows the hydrophobicity angle and roll-off angle of the embodiments.

[0085] Test location 1 2 3 4 5 Hydrophobic angle / ° 125 130 132 135 138 Roll angle / ° 10 12 12 8 8

[0086] The Cr / CrO in this embodiment x N y The coating has good hydrophobicity. The hydrophobic angle of the coating is 110°≤θ≤150° and the roll-off angle is α≤15°. The larger the hydrophobic angle and the smaller the roll-off angle, the better the hydrophobic and non-stick properties.

[0087] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A non-stick coating for a non-stick pan, characterized in that, The non-stick coating includes a chromium transition layer (2) on the surface of the metal pot substrate (1) and a chromium oxynitride layer (3) on the chromium transition layer (2); The oxygen content of the chromium transition layer (2) is 0.1~2 at.%, with the remainder being chromium; The chromium oxide layer (3) has a chromium content of 40-50 at.%, an oxygen content of 25-35 at.%, and the remainder is nitrogen; A chromium / chromium oxynitride coating was prepared by radio frequency reactive magnetron sputtering deposition. (3) Deposition of chromium oxide layer: Introduce reaction gas, open the Cr2O3 target, and carry out deposition; The reaction gas is nitrogen, with a flow rate of 80-90 sccm and a vacuum degree of 0.5-0.7 Pa; The power of the Cr2O3 target is 120~125 W; The anti-stick coating contains chromium oxide and nitride. The high hardness and high melting point of chromium nitride give the coating high hardness and thermal stability, while the presence of chromium oxide gives the coating good corrosion resistance. The non-stick coating has good hydrophobicity, with a hydrophobic angle of 110°≤θ≤150° and a roll-off angle of α≤15°, exhibiting good hydrophobic and non-stick properties.

2. A non-stick coating for a non-stick pan according to claim 1, wherein The anti-stick coating comprises chromium oxide and nitride in a mass ratio of 2:(4-5).

3. A non-stick coating for a non-stick pan according to claim 1, wherein The total thickness of the anti-stick coating is 8.2~9.5 μm.

4. A non-stick coating for a non-stick pan according to claim 3, wherein The thickness of the chromium transition layer (2) is 0.1~0.3 μm, and the thickness of the chromium oxynitride layer (3) is 7.9~9.2 μm.

5. A method for preparing an anti-stick coating for a non-stick pan as described in any one of claims 1 to 4, characterized in that, The method includes the following steps: (1) Pretreatment of metal pot substrate (1): The metal pot substrate (1) is roughened, then cleaned and dried; (2) Environmental preparation: Place the metal pot base (1) into the vacuum chamber and heat it; (3) Ion etching cleaning of metal pot substrate (1): A constant flow of ionized gas is introduced to bombard the metal pot substrate (1); (4) Chromium transition layer (2) deposition: Open the Cr target and perform deposition; (5) Nitrogen oxide chromium layer (3) deposition.

6. A method of making a non-stick coating for a non-stick pan according to claim 5, wherein, In step (1), the roughness of the roughened surface is 0.2~5.6 μm, the cleaning solution is water or ethanol, and the drying gas is nitrogen or dry air.

7. A method of making a non-stick coating for a non-stick pan according to claim 5, wherein, The pressure in the vacuum chamber in step (2) is 1.4 x 10 -4 ~1.5 x 10 -4 Pa, and the temperature is 380~400 ℃.

8. A method of making a non-stick coating for a non-stick pan according to claim 5, wherein, In step (3), the ionizing gas is argon, with a flow rate of 50~60 sccm and a vacuum degree of 0.2~0.4 Pa; The matrix bias voltage is -750~-700 V, the ion ionization voltage is 900~1200 V, and the bombardment time is 5~10 min.

9. The method for preparing an anti-stick coating for a non-stick pan according to claim 5, characterized in that, The temperature in step (4) is 420~430 ℃; The Cr target power is 100~110 W, the deposition bias voltage is -25~-20 V, and the time is 20~25 min.

10. The method of claim 5, wherein the non-stick coating is prepared by a process comprising: The temperature in step (5) is 420~430 ℃; The deposition bias was -25 to -20 V, and the time was 6 to 6.2 h.

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