A method for preparing a fluorine-free nano-ceramic non-stick coating vacuum plating film for a pot

Abstract

The application discloses a fluorine-free nanometer ceramic non-stick coating vacuum plating preparation method for a pot, and belongs to the technical field of kitchen utensil coating. x C y The silicon-based ceramic functional film is cooled to obtain a finished product. The application adopts a double-layer composite nanometer ceramic coating structure, does not add fluorine substances in the whole process, and the coating Vickers hardness can reach 2200HV, is not damaged at high temperature of 400 DEG C, has excellent hydrophobic and oleophobic properties, and has durable non-stick effect. Meanwhile, the substrate is activated by ion bombardment, the coating adhesion and wear resistance are greatly improved, the problems of traditional PTFE fluorine-containing coating, such as toxicity, easy wear and poor high-temperature resistance, are solved, the process is stable and has strong universality, and is suitable for large-scale production of various metal pots.

Description

Technical Field

[0001] This invention relates to the field of kitchenware surface coating preparation technology, specifically to a method for preparing a fluorine-free nano-ceramic non-stick coating for cookware using vacuum deposition. Background Technology

[0002] Traditional non-stick pans generally use a fluorinated non-stick coating made of polytetrafluoroethylene (PTFE). This coating has excellent non-stick properties due to its extremely low surface free energy and coefficient of friction, and is therefore widely used on the surfaces of various metal cookware. However, PTFE coatings have significant drawbacks: when the ambient temperature exceeds 260℃, PTFE decomposes, releasing toxic fumes that can easily cause discomfort to the human body. Even at normal cooking temperatures, long-term use will continue to release harmful chemicals, posing a significant health hazard.

[0003] Meanwhile, PTFE coatings have low hardness and poor wear resistance. Using metal kitchen utensils for scraping, abrasive cleaning, or high-temperature washing in dishwashers can all cause the coating to scratch, peel off, and crack. The peeling coating debris mixed into the food further exacerbates health risks and significantly shortens the lifespan of the cookware.

[0004] To address the aforementioned issues, the industry has begun developing fluorine-free non-stick coating technology. Existing conventional ceramic coatings suffer from poor adhesion, insufficient high-temperature resistance, and weak non-stick durability, failing to meet multiple application requirements such as high hardness, high temperature resistance, long-lasting non-stick performance, and safety and non-toxicity. Based on this, this invention proposes a vacuum deposition method for preparing a double-layer composite nano-ceramic coating. The resulting fluorine-free coating possesses high adhesion, high hardness, high temperature resistance, and hydrophobic and oleophobic properties, completely eliminating fluorine-based raw materials, ensuring safe use, and significantly extending service life. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing PTFE fluorine-containing coatings, such as toxicity, poor wear resistance, and insufficient high-temperature resistance, as well as the weak adhesion and poor non-stick effect of ordinary ceramic coatings. This invention provides a vacuum coating preparation method for a fluorine-free nano-ceramic non-stick coating for cookware. By preparing a double-layer composite nano-ceramic coating through a vacuum plasma coating process, a comprehensive effect of fluorine-free safety, high hardness, strong wear resistance, high temperature resistance, and long-lasting non-stick performance is achieved.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing a vacuum coating of a fluorine-free nano-ceramic non-stick coating for cookware, comprising the following steps: S1 Substrate Pretreatment: Select aluminum alloy, stainless steel or titanium alloy as cookware substrate, perform ultrasonic cleaning on the substrate to remove surface oil, dust and oxidation impurities, and dry after cleaning to ensure that the substrate surface is clean and free of residual moisture. S2 Vacuum Furnace Preparation and Heating: Place the dried cookware inside the vacuum furnace and evacuate the furnace to achieve a background vacuum of 3.0 × 10⁻⁶. −4 Pa, while simultaneously raising the furnace temperature to 300℃; S3 Ion Bombardment Activation: Argon gas is introduced into the vacuum furnace, and the argon gas flow rate is controlled at 1000 sccm to maintain the vacuum degree in the furnace at 3.0 Pa; the bias power supply is turned on, and the voltage is set to 600V and the duty cycle is 50% to perform ion bombardment activation treatment on the cookware substrate for 30 minutes to improve the surface activity of the substrate and enhance the coating adhesion. S4 bottom composite film deposition: Cr layer, CrSi mixed layer and CrSiN mixed nitride layer are deposited sequentially in a vacuum environment to form a bottom composite film with high adhesion and high hardness. S5 surface functional film deposition: SiO2 is deposited on the surface of the underlying composite film. x C y Silicon-based ceramic hybrid film forms a hydrophobic, oleophobic, and high-temperature resistant non-stick surface film; S6 Post-processing: After all coating processes are completed, turn off the gas supply system and coating power supply, wait for the vacuum furnace to cool naturally to room temperature, take out the cookware, and package it into storage after inspection of appearance and performance.

[0007] Furthermore, the Cr layer plating process in S4 involves: introducing argon gas at a flow rate of 50 sccm, and controlling the vacuum level inside the furnace to (1~3.0) × 10⁻⁶. −1 Pa; bias voltage 100V, duty cycle 50%, Cr target current 15A, coating time 90min.

[0008] Furthermore, the CrSi mixed layer deposition process in S4 involves: introducing argon gas at a flow rate of 50 sccm, and controlling the vacuum level inside the furnace to (1~3.0) × 10⁻⁶. −1 Pa; bias voltage 100V, duty cycle 50%, Cr target current 15A, Si target power 3kW, coating time 30min; chromium content in the CrSi mixed layer is 60% by mass and silicon content is 40% by mass.

[0009] Furthermore, the CrSiN mixed nitride layer deposition process in S4 involves introducing argon and nitrogen gas, with an argon flow rate of 50 sccm and a nitrogen flow rate of 30 sccm, and controlling the vacuum level inside the furnace to (1~3.2)×10⁻⁶. −1 Pa; bias voltage 100V, duty cycle 50%, Cr target current 15A, Si target power 3kW, coating time 120min; the mass percentage of chromium in the CrSiN mixed nitride layer is 50%, the mass percentage of silicon is 30%, and the mass percentage of nitrogen is 20%.

[0010] Furthermore, in S5, SiO xC y Silicon-based ceramic hybrid film deposition process: Argon, acetylene, and oxygen are introduced, with argon flow rate of 50 sccm, acetylene flow rate of 50 sccm, and oxygen flow rate of 30 sccm. The vacuum degree inside the furnace is controlled at (1~2.8)×10⁻⁶. −1 Pa; bias voltage 100V, duty cycle 50%, Cr target current 15A, Si target power 3kW, coating time 120min; SiO x C y The membrane contains 30% silicon, 30% oxygen, and 40% carbon by mass.

[0011] Furthermore, the S1 ultrasonic cleaning uses a neutral cleaning solution, a cleaning temperature of 40~60℃, and a drying temperature of 80~120℃. Beneficial effects

[0012] 1. Safe and environmentally friendly: This invention does not use fluorine-based raw materials throughout the entire process. The coating is made of pure inorganic nano-ceramic material. There is no decomposition of toxic substances or release of harmful gases under high temperature conditions, which completely solves the health hazards of traditional PTFE coatings.

[0013] 2. Excellent high temperature resistance: The prepared composite coating can withstand long-term baking at 400℃ without yellowing, discoloration, or peeling. It is suitable for various cooking scenarios such as open flame and induction cooker, and the coating will not be damaged even when the empty pot is dry-heated.

[0014] 3. High hardness and strong wear resistance: The overall Vickers hardness of the coating can reach 2200HV, which is 10 times the hardness of ordinary stainless steel substrate. It can withstand the scraping of metal cookware and regular grinding and cleaning. The coating is not easy to scratch or peel off, which greatly extends the service life of cookware.

[0015] 4. Excellent and long-lasting non-stick effect: Surface SiO x C y The silicon-based ceramic membrane has an average water droplet contact angle of 108°, low surface energy, and excellent hydrophobic and oleophobic properties, making it easy for food to adhere and clean.

[0016] 5. Strong coating adhesion: Through the combination design of ion bombardment activation substrate + three-layer gradient bottom film, the coating is tightly bonded to the metal substrate and will not peel or delaminate after alternating hot and cold temperatures and long-term use. Attached Figure Description

[0017] Figure 1 The process flow diagram of this invention is as follows: Ultrasonic cleaning and drying of the product → Placing the product in a vacuum furnace → Vacuuming → Heating → Ion bombardment activation → Vacuum coating of the bottom composite film → Vacuum coating of the surface functional film → Cooling and unloading from the furnace → Inspection and packaging. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to embodiments, comparative examples, and performance test data. The equipment and raw materials used in this invention are all commercially available conventional products, without any special limitations; performance testing standards: Vickers hardness is performed according to GB / T4340.1; water droplet contact angle is measured using a contact angle measuring instrument; high temperature resistance test involves continuous baking at 400℃ over an open flame for 24 hours; abrasion resistance test involves 10,000 cycles of reciprocating scraping using an abrasion testing machine; non-stick performance is determined using standard egg-frying and fish-frying tests.

[0019] I. Examples (5 sets in total, using the complete process of this invention, distinguishing different substrates and fine-tuning process parameters) Example

[0020] Substrate: 304 stainless steel. Cookware preparation steps: S1. Substrate pretreatment: Use neutral cleaning solution, ultrasonic cleaning at 50℃ for 15 minutes, and hot air drying at 100℃ to ensure that the surface is free of oil and moisture. S2. Vacuum heating in the oven: Place the cookware in the vacuum oven and evacuate to a vacuum level of 3.0 × 10⁻⁶. −4 Pa, heated to 300℃; S3. Ion bombardment activation: Argon gas is introduced at a flow rate of 1000 sccm, vacuum degree of 3.0 Pa, bias voltage of 600 V, duty cycle of 50%, and bombardment is carried out for 30 min. S4. Deposition of the underlying composite film: ① Cr layer: Argon gas 50 sccm, vacuum degree 2.0 -1 Pa, bias voltage 100V, duty cycle 50%, Cr target current 15A, coating time 90min; ② CrSi mixed layer: argon gas 50 sccm, vacuum degree 2.0 × 10 −1 Pa, bias voltage 100V, duty cycle 50%, Cr target 15A, Si target 3kW, coating time 30min; composition: Cr 60%, Si 40%; ③ CrSiN layer: Argon gas 50 sccm, nitrogen gas 30 sccm, vacuum degree 2.5×10 −1 Pa, bias voltage 100V, duty cycle 50%, Cr target 15A, Si target 3kW, coating time 120min; composition: Cr 50%, Si 30%, N 20%; S5, surface SiO x C y Film deposition: Argon 50 sccm, Acetylene 50 sccm, Oxygen 30 sccm, Vacuum degree 2.2 × 10⁻⁶ −1Pa, bias voltage 100V, duty cycle 50%, Cr target 15A, Si target 3kW, coating time 120min; composition: Si 30%, O 30%, C 40%; S6. Allow to cool naturally to room temperature, inspect and package to obtain the finished cookware.

[0021] Example 2 Substrate: Aluminum alloy. Cookware preparation steps: The overall process flow, process parameters, and component ratios are completely consistent with those in Example 1; only the substrate is replaced with aluminum alloy.

[0022] Example 3 Substrate: Titanium alloy cookware preparation steps: The overall process flow, process parameters, and component ratios are completely consistent with those in Example 1; only the substrate is replaced with titanium alloy.

[0023] Example 4 Substrate: 304 stainless steel cookware. Difference from Example 1: The vacuum degree during the ion bombardment stage was adjusted to 2.8 Pa, while the other process parameters, component ratios, and processes remained unchanged.

[0024] Example 5 Substrate: 304 stainless steel cookware. Difference from Example 1: SiO x C y The vacuum level during the coating stage was adjusted to 2.5 × 10⁻⁶. −1 Pa, with all other process parameters, component ratios, and flow remaining unchanged.

[0025] II. Comparative Example Comparative Example 1 (Traditional PTFE fluorinated coated cookware) Using conventional commercial processes, a polytetrafluoroethylene non-stick coating is sprayed onto the surface of 304 stainless steel cookware. The coating thickness is consistent with the total coating thickness in the embodiment of this invention, which is a common industry standard product.

[0026] Comparative Example 2 (substrate composite film omitted, only surface SiO2 deposited) x C y membrane) The substrate is 304 stainless steel cookware. The pretreatment, vacuuming, and ion bombardment processes are the same as in Example 1; the Cr layer, CrSi layer, and CrSiN layer are omitted, and SiO is directly plated on the substrate surface. x C y The film, coating parameters, and composition are the same as in Example 1.

[0027] Comparative Example 3 (No ion bombardment activation process, complete double-layer coating) The substrate is 304 stainless steel cookware. The S3 ion bombardment activation step is omitted. All other process flows, process parameters, coating structure, and component ratios are completely consistent with those in Example 1.

[0028] III. Performance Test Results and Data Comparison Table Five sets of example samples and three sets of comparative samples were uniformly tested for five indicators: Vickers hardness, water droplet contact angle, 400℃ high temperature resistance, 10,000-cycle abrasion resistance, and non-stick effect. The test results are shown in the table below: Example 1 304 stainless steel 2200 108 No discoloration, no delamination No scratches, coating intact Excellent, completely non-stick, washable with water. Example 2 aluminum alloy 2180 107 No discoloration, no delamination No scratches, coating intact Excellent, completely non-stick, washable with water. Example 3 Titanium alloy 2210 109 No discoloration, no delamination No scratches, coating intact Excellent, completely non-stick, washable with water. Example 4 304 stainless steel 2190 108 No discoloration, no delamination No scratches, coating intact Excellent, completely non-stick, washable with water. Example 5 304 stainless steel 2200 107 No discoloration, no delamination No scratches, coating intact Excellent, completely non-stick, washable with water. Comparative Example 1 (PTFE coating) 304 stainless steel 280 110 Yellowing and localized softening of the coating Numerous scratches and localized peeling Excellent initially, but deteriorates after repeated use. Comparative Example 2 (surface membrane only) 304 stainless steel 1420 108 Slight discoloration, localized delamination Obvious scratches, large areas of peeling It's normal for it not to stick; the coating is prone to peeling off. Comparative Example 3 (No Ion Bombardment) 304 stainless steel 2170 108 No discoloration, slight peeling at the edges Moderate scratches, localized delamination It's normal for it not to stick; poor coating adhesion. IV. Test Result Analysis 1. Hardness analysis: The Vickers hardness of the coating in the embodiments of the present invention is stable at 2180~2210HV, which is much higher than that of the traditional PTFE coating (280HV); the hardness of Comparative Example 2 is significantly reduced due to the lack of the underlying hard composite film; the hardness of Comparative Example 3 is slightly reduced due to the absence of ion bombardment, proving that the underlying three-layer composite film + ion bombardment is the core to achieving high hardness.

[0029] 2. Non-stick performance analysis: The water droplet contact angle of each group of samples was between 107 and 110°. The non-stick ability of the silicon-based ceramic film on the surface of the present invention is basically the same as that of the PTFE coating, achieving the same non-stick effect. Moreover, the present invention is fluorine-free and has higher safety.

[0030] 3. High temperature resistance performance analysis: Under long-term high temperature test at 400℃, the coatings of all examples remained intact; traditional PTFE coatings failed at high temperature; comparative examples 2 and 3 showed delamination and film removal problems, proving that the double-layer composite structure + ion bombardment activation can significantly improve the coating's high temperature resistance and bonding strength.

[0031] 4. Wear resistance analysis: The coating of the sample in the example remained intact after 10,000 scratches, showing excellent wear resistance; the PTFE coating, single surface film, and sample without ion bombardment all showed scratches and peeling, verifying the effect of the gradient bottom film and activation process of the present invention on improving wear resistance and adhesion.

[0032] 5. Substrate compatibility: The process of this invention can be adapted to three mainstream cookware substrates: stainless steel, aluminum alloy, and titanium alloy. The product has a wide range of applications and strong process versatility.

[0033] The scope of protection of this invention is not limited to the above five embodiments. Any adjustments made by those skilled in the art to conventional process parameters such as vacuum degree, gas flow rate, and coating time, or the substitution of the same type of metal cookware substrate, without departing from the core process, coating structure, and component ratio of this invention, all fall within the scope of protection of this invention. This invention uses vacuum plasma deposition to prepare a double-layer fluorine-free nano-ceramic coating, fundamentally solving the safety hazards and durability defects of traditional fluorine-containing non-stick pans, and possesses extremely high market promotion value.

[0034] Compared to existing technologies, this invention innovates in both coating structure and preparation process, completely eliminating the health risks posed by fluorides while significantly improving the overall service life of the coating. This preparation method is adaptable to various cookware substrates, and the production process is simple and controllable, possessing excellent industrialization prospects and market promotion value. The scope of protection of this invention is defined by the appended claims.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. The vacuum coating process for fluorine-free nano-ceramic non-stick coating proposed in this invention is mature, reliable, and can be widely applied to the large-scale production of various metal cookware.

Claims

1. A method for preparing a fluorine-free nano-ceramic non-stick coating for cookware using vacuum deposition, characterized in that, Includes the following steps: S1. Substrate pretreatment: The cookware substrate is ultrasonically cleaned and then dried. The cookware substrate is aluminum alloy, stainless steel or titanium alloy. S2. Vacuuming in the oven: Place the dried cookware into the vacuum oven, evacuate the oven, and heat it to achieve a vacuum level of 3.0 × 10⁻⁶. −4 Pa, the furnace temperature rises to 300℃; S3 Ion Bombardment Activation: Argon gas is introduced into the vacuum furnace, and the argon gas flow rate is controlled at 1000 sccm. The vacuum degree in the furnace is maintained at 3.0 Pa. The bias power supply is turned on, and the voltage is set to 600V and the duty cycle is 50%. The cookware substrate is subjected to ion bombardment treatment for 30 minutes. S4. Underlying composite film coating: Cr layer, CrSi mixed layer and CrSiN mixed nitride layer are deposited sequentially in a vacuum environment to form an adhesion layer and a high-hardness underlying film. S5, Surface functional film coating: Continue to deposit SiO2 in the vacuum furnace. x C y A silicon-based ceramic hybrid film forms a hydrophobic and oleophobic non-stick surface film; S6. Post-processing: After the coating is completed, turn off the coating power and gas supply system. After the vacuum furnace cools down naturally, take out the cookware, and then inspect and package it to obtain the finished product.

2. The method for preparing a vacuum coating of fluorine-free nano-ceramic non-stick coating for cookware according to claim 1, characterized in that, The plating process for the Cr layer in S4 is as follows: argon gas is introduced at a flow rate of 50 sccm, and the vacuum level inside the furnace is controlled at (1~3.0)×10⁻⁶. −1 Pa; bias voltage 100V, duty cycle 50%, Cr target current 15A, coating time 90min.

3. The method for preparing a vacuum coating of fluorine-free nano-ceramic non-stick coating for cookware according to claim 1, characterized in that, The deposition process of the CrSi mixed layer in S4 is as follows: argon gas is introduced at a flow rate of 50 sccm, and the vacuum degree inside the furnace is controlled at (1~3.0)×10. −1 Pa; bias voltage 100V, duty cycle 50%, Cr target current 15A, Si target power 3kW, coating time 30min; the CrSi mixed layer contains 60% chromium and 40% silicon.

4. The method for preparing a vacuum coating of fluorine-free nano-ceramic non-stick coating for cookware according to claim 1, characterized in that, The deposition process of the CrSiN mixed nitride layer in S4 is as follows: argon and nitrogen are introduced, with an argon flow rate of 50 sccm and a nitrogen flow rate of 30 sccm. The vacuum degree inside the furnace is controlled at (1~3.2)×10⁻⁶. −1 Pa; bias voltage 100V, duty cycle 50%, Cr target current 15A, Si target power 3kW, coating time 120min; the CrSiN mixed nitride layer contains 50% chromium, 30% silicon and 20% nitrogen.

5. The method for preparing a vacuum coating of fluorine-free nano-ceramic non-stick coating for cookware according to claim 1, characterized in that, SiO in S5 x C y The deposition process for the silicon-based ceramic hybrid film is as follows: argon, acetylene, and oxygen are introduced, with argon flow rate of 50 sccm, acetylene flow rate of 50 sccm, and oxygen flow rate of 30 sccm. The vacuum degree inside the furnace is controlled at (1~2.8)×10⁻⁶. −1 Pa; bias voltage 100V, duty cycle 50%, Cr target current 15A, Si target power 3kW, coating time 120min; the silicon-based ceramic hybrid film contains 30% silicon, 30% oxygen and 40% carbon.

6. The method for preparing a vacuum coating of fluorine-free nano-ceramic non-stick coating for cookware according to claim 1, characterized in that, The prepared nano-ceramic non-stick coating has a Vickers hardness of 2200 HV and an average water droplet contact angle of 108°. The coating can withstand long-term use at a high temperature of 400℃ without discoloration or delamination.

7. The method for preparing a vacuum coating of fluorine-free nano-ceramic non-stick coating for cookware according to claim 1, characterized in that, The bottom composite film is tightly bonded to the cookware substrate, which improves the coating adhesion and wear resistance; the surface SiO... x C y The silicon-based ceramic hybrid film has hydrophobic, oleophobic, and high-temperature resistant properties, achieving a non-stick effect on cookware; the overall coating does not contain fluorine-containing substances.

8. The method for preparing a vacuum coating of fluorine-free nano-ceramic non-stick coating for cookware according to claim 1, characterized in that, In S1, ultrasonic cleaning uses a neutral cleaning solution, the cleaning temperature is 40~60℃, and the drying temperature is 80~120℃ to ensure that the surface of the cookware substrate is free of oil, impurities and moisture.

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