Method for forming an amorphous metal coating on a steel workpiece

Abstract

This invention provides a method for forming a coating on a steel workpiece and a coated steel workpiece prepared using this method. Compared with conventional methods, the comprehensive and innovative method provided by this invention for developing amorphous metal coatings can significantly improve the service life, efficiency, and overall performance of steel workpieces such as cutting tools.

Description

Technical Field

[0001] This invention relates to the field of metal coatings, and more particularly to a method for forming a coating on a steel workpiece and a coated steel workpiece prepared by the method. Background Technology

[0002] In food processing plants, cutting tools (such as knives and blades) face harsh operating conditions, which can lead to severe wear and corrosion, resulting in a decline in performance over time. The challenges facing food cutting tools include: (1) Wear and corrosion: Food cutting tools are frequently exposed to moisture, acidic substances, and salt in food, leading to severe corrosion and wear; (2) Durability: Due to the lack of high-performance coatings, cutting tools require frequent replacement and maintenance, thus increasing operating costs. Traditional coatings often fail to meet the durability and protection requirements of such applications.

[0003] Blade protective coatings are crucial for maintaining the performance and durability of blades used in a wide range of applications. These coatings act as a barrier against corrosion, abrasion, and other forms of degradation during blade operation. By providing a protective layer, blade coatings help extend blade life, thus ensuring long-term functionality and efficiency. Additionally, protective coatings enhance the blade's resistance to harsh environmental conditions, chemicals, and abrasive materials, reducing the need for frequent maintenance and replacement. Blade protective coatings play a key role in maintaining the integrity and performance of blades, ultimately leading to cost savings and improved operational efficiency.

[0004] Amorphous materials represent a new class of advanced materials, exhibiting attractive combined properties such as high strength / hardness and excellent wear / corrosion resistance. These superior properties primarily stem from the disordered atomic arrangement of amorphous materials, resulting in the absence of grain boundaries and defects in their microstructure. The non-equilibrium nature of amorphous materials contributes to their excellent properties but also presents significant challenges to their processing. Although rapid solidification (i.e., casting methods for processing amorphous alloys) is well-established, the necessity of simultaneous mold filling and rapid cooling rates limits the range of geometries that can be formed. These processing difficulties, along with low tensile ductility and toughness, may limit the application of amorphous materials as a bulk structural material. However, amorphous materials can serve as excellent candidates for wear-resistant / corrosion-resistant coatings on steel substrates.

[0005] Therefore, there is an urgent need for an innovative solution that can provide an amorphous metal coating on the surface of cutting tools such as blades, significantly extending their service life and improving their performance. Summary of the Invention

[0006] This invention aims to develop an innovative and robust amorphous metallic coating for steel workpieces, overcoming at least one limitation of existing coatings in the prior art. The inventors first employ three pretreatment methods to smooth the substrate and enhance compatibility; then, an intermediate layer is introduced as a bridge between the substrate and the final coating to further enhance coating adhesion; subsequently, an iron-based coating with optimized iron content and containing small amounts of additional elements such as chromium, molybdenum, and boron is selected, which improves the mechanical and chemical properties of the coating, thereby achieving this invention.

[0007] In one aspect, the present invention provides a method for forming a coating on a steel workpiece, comprising: (1) The steel workpiece is etched to obtain the etched steel workpiece; (2) Using the etched steel workpiece as the anode, electropolishing is performed on it to obtain an electropolished steel workpiece; (3) Plasma treatment is performed on the electropolished steel workpiece to obtain a plasma-treated steel workpiece; (4) An intermediate layer is deposited on the surface of the plasma-treated steel workpiece to obtain a steel workpiece with an intermediate layer; (5) Depositing an amorphous metal coating on a steel workpiece with an intermediate layer, wherein the amorphous metal coating is composed of an amorphous alloy selected from the following: zirconium-based amorphous alloy, copper-based amorphous alloy, nickel-based amorphous alloy, aluminum-based amorphous alloy, titanium-based amorphous alloy, iron-based amorphous alloy or palladium-based amorphous alloy.

[0008] A second aspect of the present invention provides a coated steel workpiece, comprising: steel base; The intermediate layer on the surface of the steel substrate; and An amorphous metal coating on the surface of a steel substrate with the intermediate layer; The coated steel workpiece is made by the method described in the first aspect.

[0009] In this invention, the inventors provide a novel and robust method for preparing an amorphous metallic coating on steel workpieces, aiming to improve the performance and service life of cutting tools. The method includes a comprehensive surface pretreatment process and a subsequent PVD coating process to form an intermediate layer and an amorphous metallic coating. Coated steel workpieces prepared using this method offer several advantages, such as: Enhanced bonding strength: The comprehensive three-step pretreatment process significantly improves surface energy and enhances the compatibility of the coating with the substrate, ensuring a strong and durable coating.

[0010] Exceptional durability: The intermediate layer and optimized alloy coating form provide excellent abrasion resistance and the ability to withstand harsh conditions.

[0011] Excellent corrosion and wear resistance: The iron-based coating with added elements such as chromium, molybdenum, and boron provides excellent corrosion and wear resistance, ensuring that steel workpieces maintain their performance over a long period of time.

[0012] Extremely low coefficient of friction: Nano-scratch tests show that the iron-based coating has an extremely smooth surface and a very low coefficient of friction. This not only enhances hardness and durability, but also significantly reduces heat generation during use, thereby minimizing wear and further extending the service life of the coating.

[0013] Strong antibacterial properties: According to ISO 22196 standard, this iron-based coating exhibits strong antibacterial activity against common bacteria such as Staphylococcus aureus and Escherichia coli, with an inhibition rate exceeding 99.99%. This indicates that the coating has a significant antibacterial effect, enhancing hygiene and safety in applications such as food processing.

[0014] In summary, this invention provides a comprehensive and innovative method for preparing amorphous metal coatings, which can significantly improve the service life, efficiency, and overall performance of steel workpieces such as cutting tools. Attached Figure Description

[0015] The accompanying drawings, included to provide a further understanding of the invention, are incorporated in and form part of this specification. The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0016] Figure 1 The appearance of the Fe-31 protective coating after 48 hours of exposure to a salt spray environment is shown. Figure 2 The adhesion test results of a coating according to one embodiment of the present invention, in accordance with the Daimler-Benz Rockwell-C (HRC-DB) test standard, are shown (left figure is the standard; right figure is the test results of the sample). Detailed Implementation

[0017] The present invention will now be clearly and completely described in conjunction with its embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention. Furthermore, the wording and terminology used in this specification are for descriptive purposes only and should not be considered as limiting the present invention.

[0018] Although the numerical ranges and parameters used to define the broad scope of the invention are approximate, the values ​​given in the specific embodiments are recorded as accurately as possible. However, any numerical value inherently contains some error due to the standard deviation of its respective test measurement.

[0019] Furthermore, it should be understood that any numerical range listed in this specification is intended to encompass all subranges it contains. For example, the range “1 to 10” should include all subranges between (inclusive) the minimum value of 1 and the maximum value of 10, i.e., the minimum value is equal to or greater than 1 and the maximum value is equal to or less than 10.

[0020] As used in this article, the singular forms “one” and “this” have plural meanings unless the context explicitly states otherwise or clearly implies otherwise. Expressions such as “first,” “second,” and “third” are used for distinction purposes only and do not define any order, priority, or rank.

[0021] As used herein, the terms “about” and “substantially” are used for measurable values ​​and their ranges due to expected errors or variations known to those skilled in the art (e.g., limitations and variability in measurement). The term “about” also indicates that the stated numerical value allows for a slight degree of imprecision (i.e., close to the exact value; approximately or reasonably close to the value; almost equal to the value). If those skilled in the art cannot understand the imperfection allowed by “about” in its ordinary sense, then “about” herein covers at least the variations that may arise from conventional measurement methods and the use of such parameters. Furthermore, disclosing a range of values ​​implies disclosing all specific values ​​within that range and further subdivisions of the overall range.

[0022] As used herein, the terms “comprising,” “having,” “including,” or “containing” are inclusive, open-ended expressions that do not exclude additional, unlisted elements or methodological steps.

[0023] As used herein, the term "consisting of" and its grammatical variations should be understood in the context of this invention to exclude any unspecified elements, ingredients, or method steps. As used herein, the term "substantially composed of" and its grammatical variations should be understood in the context of this invention to include the specified elements, materials, ingredients, or method steps, as well as any additional elements, materials, ingredients, or method steps that do not materially affect the essential and novel features of the content. It should be understood that when using the term "comprising" and its grammatical variations, if no additional elements, materials, ingredients, or method steps that would materially affect the essential and novel features of the content are included, "comprising" can be replaced with "consisting of" or "substantially composed of" and their grammatical variations.

[0024] While certain specific aspects of the invention will be described in detail, those skilled in the art will understand that various modifications or alternatives may be made to these details in light of the overall teachings of the invention. Therefore, the specific embodiments disclosed are for illustrative purposes only and are not intended to limit the scope of the invention; the scope of the invention should be determined by the appended claims and all their equivalents in their full breadth.

[0025] As previously stated, the present invention aims to provide an innovative and robust amorphous metal coating for steel workpieces to overcome at least one limitation associated with existing coatings described in the prior art.

[0026] A first aspect of the present invention provides a method for forming a coating on a steel workpiece, comprising: (1) The steel workpiece is etched to obtain the etched steel workpiece; (2) Using the etched steel workpiece as the anode, electropolishing is performed on it to obtain an electropolished steel workpiece; (3) Plasma treatment is performed on the electropolished steel workpiece to obtain a plasma-treated steel workpiece; (4) An intermediate layer is deposited on the surface of the plasma-treated steel workpiece to obtain a steel workpiece with an intermediate layer; (5) Depositing an amorphous metal coating on a steel workpiece with an intermediate layer, wherein the amorphous metal coating is composed of an amorphous alloy selected from the following: zirconium-based amorphous alloy, copper-based amorphous alloy, nickel-based amorphous alloy, aluminum-based amorphous alloy, titanium-based amorphous alloy, iron-based amorphous alloy or palladium-based amorphous alloy.

[0027] Those skilled in the art should understand that the method of this application is applicable to a variety of types of steel workpieces, i.e., steel substrates, including but not limited to carbon steel, high-speed steel, pearlitic steel and austenitic steel.

[0028] Those skilled in the art will understand that surface pretreatment is a crucial step in preparing the metal surface for subsequent coating processes, enhancing the adhesion, durability, and overall performance of the coating. In this invention, the inventors employ three pretreatment methods: etching, electropolishing, and plasma treatment, which collectively enhance the bonding strength and durability of the coating on the metal surface.

[0029] First, the steel substrate is etched, a chemical process in which the metal is immersed in an acidic or alkaline solution to selectively remove material from the surface to form a microstructure similar to the surface of a lotus leaf.

[0030] Subsequently, the steel substrate undergoes electropolishing, an electrochemical finishing process that removes a thin layer of material from the surface of metal parts. This process yields a smoother, cleaner surface. Electropolishing smooths out peaks and valleys, improving surface roughness. Unlike mechanical finishing, electropolishing does not cause smearing, bending, stress, or breakage on the crystalline metal surface. Simultaneously, surface defects are deburred and removed. Electropolishing can also remove small pieces of displaced surface material that may be stuck and broken at the microscopic level.

[0031] Finally, the steel substrate is subjected to plasma treatment, a surface modification process that enhances adhesion and increases its affinity for coatings or adhesives by altering the surface properties of the material. During plasma treatment in an air atmosphere, the active substances generated by the plasma clean the surface, remove contaminants, and activate the surface by forming functional groups that promote bonding.

[0032] In one embodiment, the etching process in (1) is carried out in an etching solution containing ferric chloride.

[0033] In the context of this invention, the term "amorphous metal" (also known as metallic glass) can be understood to refer to a unique class of materials with an amorphous atomic structure. Unlike traditional crystalline metals, which have atoms arranged in a regular, repeating lattice structure, the atoms of amorphous metals are arranged in a disordered manner. The lack of grain boundaries and dislocations endows amorphous metals with extremely high strength and hardness, while the disordered atomic structure enhances their wear resistance and corrosion resistance, making them ideal coating materials.

[0034] Ferro-based amorphous metal coatings are a type of metallic glass coating composed of Fe and other elements such as Ni, Cr, Co, Si, B, and Nb. Ferro-based amorphous metals can exhibit ultra-high strength. Appropriate composition can be optimized through fine-tuning the formulation. Amorphous metal coatings can be enhanced with Sn additives to reduce the coefficient of friction, improve tribological properties, and smooth the surface. The addition of chromium and molybdenum can improve corrosion resistance by forming a protective oxide layer, while copper or aluminum additives are used due to their antibacterial properties to effectively destroy bacterial cells. These additives play a crucial role in optimizing the performance of amorphous metal coatings in a variety of applications.

[0035] In one embodiment, the amorphous metal coating in (5) is composed of an iron-based amorphous alloy.

[0036] In one embodiment, the iron-based amorphous alloy comprises 30-50 at.% Fe, 10-25 at.% Cr, 10-20 at.% Mo, 10-20 at.% Ti, 5-15 at.% B, 5-15 at.% C, 3-8 at.% Si, 0-10 at.% Co, and 0-5 at.% Y (at.% = atomic percentage).

[0037] In this invention, the inventors selected various iron-based amorphous metal coatings based on the percentage of iron in the alloy to examine its properties, including Fe-31 (Fe 31 Cr 15 Mo 14 C 10 B 10 Si5Ti 15), Fe-41 (Fe 41 Cr 15 Co7Mo 14 C 12 B9Y2), Fe-44 (Fe 44 Cr 15 Mo 14 C 10 B5Si5Co7) and Fe-46 (Fe 46 Cr 23 Mo 14 (B5Si5Co7). Among the coatings mentioned above, the Fe-31 coating exhibits the most stable performance.

[0038] In one specific implementation, the iron-based amorphous alloy is composed of Fe 31 Cr 15 Mo 14 C 10 B 10 Si5Ti 15 composition.

[0039] In one specific implementation, the iron-based amorphous alloy is composed of Fe 41 Cr 15 Co7Mo 14 C 12 Composed of B9Y2.

[0040] In one specific implementation, the iron-based amorphous alloy is composed of Fe 44 Cr 15 Mo 14 C 10 Composition: B5Si5Co7.

[0041] In one specific implementation, the iron-based amorphous alloy is composed of Fe 46 Cr 23 Mo 14 Composition: B5Si5Co7.

[0042] A significant challenge in developing iron-based amorphous metal coatings is the adhesion between the coating and the substrate. Direct application of iron-based amorphous metal coatings to stainless steel surfaces results in poor adhesion, as evidenced by peeling during tape testing. Even with excellent coating properties, weak adhesion can lead to peeling, corrosion, and cracking. Therefore, an interlayer is crucial for ensuring a strong bond between the coating and the substrate. To improve coating adhesion, it is essential to match the properties of the interlayer with both the coating material and the substrate, including factors such as the coefficient of thermal expansion (TEC) and mechanical properties. TEC mismatch between the substrate and coating can generate significant stress during temperature changes, leading to coating debonding and failure. By selecting an interlayer with a TEC that matches both the coating and the substrate, such stress can be minimized, thereby improving bond strength and stability. Materials such as Ti and Al, due to their suitable TEC values, are often used as buffer or adhesive layers to help enhance the bond between the coating and the substrate and ensure long-term performance and durability.

[0043] In this application, the inventors evaluated the effect of Cu, Al, Ti, or TiO as interlayer materials on enhancing the adhesion of iron-based amorphous metal coatings based on the TEC of the substrate and the protective coating. The results showed that samples using Al and Ti interlayers exhibited significantly improved adhesion performance.

[0044] In one embodiment, the intermediate layer in (4) is composed of Cu, Al, Ti, or TiO (99.9% purity). In another embodiment, the intermediate layer in (4) is composed of Al or Ti. Given Ti's excellent corrosion resistance, it is preferably chosen as the optimal intermediate layer material for subsequent PVD processes in protective coating applications.

[0045] Physical vapor deposition (PVD), sometimes also called physical vapor transport (PVT), refers to various vacuum deposition methods that can produce thin films and coatings on a substrate. The PVD process is characterized by the material transitioning from a condensed phase to a gaseous phase and then back to a thin film condensed phase. It is widely used due to its ability to produce high-quality, durable coatings with excellent adhesion and performance characteristics. Compared to traditional chemical coating methods, PVD processes generate minimal hazardous waste.

[0046] In one embodiment, the intermediate layer and the amorphous metal coating are deposited on the plasma-treated steel workpiece using physical vapor deposition (PVD) methods.

[0047] Sputtering is one of the most commonly used PVD processes, in which atoms are ejected from a target (source) by bombardment with high-energy particles (typically ions of inert gases such as argon). The ejected atoms then pass through a vacuum chamber and deposit onto a substrate to form a thin film. Sputtering can provide uniform, high-quality multilayer coatings with excellent adhesion and controllable composition, making it well-suited for this application.

[0048] In one specific implementation, the PVD method is sputtering.

[0049] Those skilled in the art will understand that sputtering technologies include magnetron sputtering, radio frequency (RF) sputtering, direct current (DC) sputtering, reactive sputtering, and other types. RF sputtering is a process that uses radio frequency AC power to improve the efficiency and control of the sputtering process. Unlike traditional DC sputtering, which uses DC power, RF sputtering generates a magnetic field around the deposition source and ionizes the atoms of the process gas. Therefore, RF sputtering has a wider range of applications and is suitable for all conductive and non-conductive materials. However, RF sputtering is most commonly used for depositing dielectric sputtering targets. Compared to DC sputtered films, RF sputtered films are smoother and have better packing density. In this application, the intermediate layer is composed of Cu, Al, Ti, or TiO, which are not all conductive, making it more suitable for RF sputtering; however, if the intermediate layer is composed of a conductive material, it can also be deposited using DC sputtering.

[0050] In one embodiment, the intermediate layer is deposited on a plasma-treated steel workpiece by radio frequency (RF) sputtering or direct current (DC) sputtering. In a specific embodiment, the sputtering is performed in an argon atmosphere at 0.1-1 Pa and 2-4 W / cm² for 5-20 minutes; preferably, the sputtering is performed in an argon atmosphere at 0.3 Pa and 2.55 W / cm² for 10 minutes.

[0051] The amorphous metal coating, such as an iron-based amorphous metal protective coating, can be synthesized through various methods including laser irradiation and spraying. In some embodiments, the protective coating is deposited directly by direct current (DC) magnetron sputtering using an iron-based amorphous metal target (99.9% purity). As mentioned earlier, since all the materials involved are metallic, DC sputtering is more suitable. DC sputtering has a higher deposition rate, making it more efficient and economical with pure metal sputtering targets.

[0052] In one embodiment, the amorphous metal coating is deposited on a steel workpiece having the intermediate layer by direct current (DC) sputtering. In a specific embodiment, DC sputtering is performed in an argon atmosphere at 0.1-1 Pa and 2-4 W / cm² for 40-100 minutes; preferably, DC sputtering is performed in an argon atmosphere at 0.3 Pa and 2.55 W / cm² for 60 minutes.

[0053] In one embodiment, the steel workpiece is a cutting tool. In a specific embodiment, the cutting tool is a blade.

[0054] A second aspect of the present invention provides a coated steel workpiece, comprising: steel base; The intermediate layer on the surface of the steel substrate; and An amorphous metal coating on the surface of a steel substrate having the intermediate layer; The coated steel workpiece is made by the method described in the first aspect.

[0055] In one embodiment, the thickness of the intermediate layer is 0-100 nm.

[0056] In one embodiment, the thickness of the amorphous metal coating is 100-900 nm.

[0057] Example In this specification, the embodiments are written in a clear and precise particular manner; however, it should be understood and acknowledged that these embodiments can be combined or separated in various ways without departing from the invention. For example, all preferred features described herein are applicable to all aspects of the invention.

[0058] Example 1: Preparation of amorphous metal coating on steel workpiece The preparation of the protective coating on the blade surface involves three pretreatment steps: etching, electropolishing, and plasma treatment, followed by the deposition of an intermediate layer and a protective coating. The pretreatment steps increase surface energy and enhance the compatibility between the coating and the substrate. The intermediate layer improves coating adhesion by connecting the substrate and the coating. Amorphous protective coatings, with their corrosion resistance, high hardness, and good adhesion, are ideal for blade applications.

[0059] The method of this application can be applied to various types of steel substrates. In this embodiment, for testing purposes, a blade protective coating is prepared on a stainless steel plate. A stainless steel plate with dimensions of 50 mm × 50 mm × 1 mm is subjected to rigorous cleaning for subsequent use, including: ultrasonic cleaning with acetone for 10 minutes, ultrasonic cleaning with ethanol for 10 minutes, and ultrasonic cleaning with distilled water for 10 minutes. After cleaning, the stainless steel plate is dried in a thermostat at 70°C.

[0060] 1.1 Pretreatment Step 1: Etching The chemical etching solution was prepared according to the following proportions: 16 g ferric chloride, 60 mL distilled water, 2 mL hydrochloric acid, 2 mL phosphoric acid, and 2 mL hydrogen peroxide. The resulting solution was stirred until homogeneous using a magnetic stirrer. The prepared chemical etching solution can be stored in a glass container.

[0061] In the etching process, firstly, the stainless steel plate is immersed in the prepared chemical etching solution and kept in a 50°C water bath for 60 minutes. Then, the treated stainless steel plate is rigorously cleaned to remove the etching solution, including: ultrasonic cleaning with acetone for 10 minutes, ultrasonic cleaning with ethanol for 10 minutes, and ultrasonic cleaning with distilled water for 10 minutes. After cleaning, the stainless steel plate is dried in a 70°C thermostat.

[0062] In the etching process, iron readily reacts with hydrochloric acid and ferric chloride, corroding the stainless steel surface to form a microstructure similar to that of a lotus leaf. The stainless steel plate pretreated in this way can then be used for the subsequent two pretreatments.

[0063] 1.2 Pretreatment Step 2: Electrolytic Polishing The electrolyte used for pretreatment is typically a high-viscosity mixture of sulfuric acid and phosphoric acid. Specifically, before starting the preparation of the electrolyte, sufficient ice and ice water are needed to cool the acid during the mixing process to prevent accidents caused by boiling or splashing of the concentrated acid. First, 765 mL of 85% concentrated phosphoric acid is measured and slowly poured into a suitably sized glass container. Second, 435 mL of 95% concentrated sulfuric acid is measured and slowly poured into the concentrated phosphoric acid, stirring with a glass rod or magnetic stir bar as it is poured. This process is carried out in an ice bath, using ice water and ice to cool the outer wall of the container in a timely manner to prevent accidents. Third, when the acid is evenly mixed and the temperature has dropped to room temperature, 8.3424 g of polyethylene glycol 6000, 2.0856 g of hexamethylenetetramine, 10.428 g of citric acid, 0.20856 g of thiourea, 12 mL of glycerol, and 48 mL of water are added, and the mixture is stirred thoroughly until homogeneous. Finally, a clear and transparent electrolyte is obtained and stored in a glass container.

[0064] In the electropolishing process, the metal part serves as the positively charged anode. The stainless steel plate treated in the above pretreatment step 1 is connected to the positive terminal of a DC power rectifier. The negatively charged cathode, typically made of zirconium, is connected to the negative terminal of the DC power rectifier. Both the cathode and anode are immersed in a temperature-controlled bath of the electrolyte solution prepared above. In pretreatment step 2, the temperature is maintained below 70°C, the voltage is maintained at 5 V, and each stainless steel plate is treated for 40 seconds.

[0065] The microscopic smoothness of the stainless steel sheet is improved after the electropolishing process.

[0066] 1.3 Pretreatment Step 3: Plasma Treatment First, an electropolished stainless steel sheet is placed in a plasma chamber. Second, the plasma chamber is evacuated to create a low-pressure environment. Third, air is introduced to establish a plasma atmosphere, and radio frequency or microwave energy is applied to generate plasma. Finally, the stainless steel sheet is treated for 30 minutes to obtain the desired surface modification. This process results in improved adhesion by increasing surface energy and creating a more chemically active surface that bonds better with coatings or adhesives.

[0067] 1.4 Coating 1: Intermediate Layer The pretreated stainless steel sheet is placed inside the cavity to achieve a basic ambient pressure level of at least 1×10⁻⁻. 4 Pa. The pressure was then increased to 0.3 Pa with argon gas, and the argon flow rate was maintained at 80 sccm throughout the sputtering process. The sputtering FR power was maintained at 200 W.

[0068] 1.5 Coating 2: Protective Coating A pre-treated stainless steel plate with an intermediate layer is placed inside the cavity to achieve a basic ambient pressure level of at least 1×10⁻⁻. 4 Pa. The pressure was then increased to 0.3 Pa with argon gas, and the argon flow rate was maintained at 80 sccm throughout the sputtering process. The sputtering DC power was fixed at 200 W.

[0069] Table 1. Preferred parameters for sputtering

[0070] *Note: Fe-31 refers to Fe-31 (Fe 31 Cr 15 Mo 14 C 10 B 10 Si5Ti 15 ).

[0071] Example 2: Coating performance testing Following the steps in Example 1, an amorphous metal coating was prepared using an Fe-31 coating and a Ti interlayer according to the parameters mentioned in Table 1. The coating was then subjected to the following performance tests: Hardness test The hardness of the coating was tested by nanoindentation test according to ISO 14577-1:2015 standard, and the results are shown in Table 2.

[0072] The standard procedure for nanoindentation testing includes: preparing the sample surface by polishing, calibrating the indenter, calibrating by measuring the indentation depth while applying a controlled load, and finally analyzing the load-displacement data to extract the relevant mechanical properties.

[0073] The hardness data of all samples were systematically calculated to evaluate the effectiveness of the protective layer. To assess the performance of the selected protective layer, four different stainless steel samples (labeled A, B, C, and D) were studied in detail, each representing a different surface condition for industrial applications. A was 301 stainless steel, B was 420 stainless steel, C was one type of 440 stainless steel, and D was another type of 440 stainless steel. Furthermore, A, B, C, and D had different roughnesses, with A being the smoothest and D the roughest.

[0074] The results showed that sample A in its bare state exhibited an average hardness of 6.2 GPa (57 HRC), which increased to 13.5 GPa after the application of the protective coating. Sample B in its uncoated state showed an average hardness of 6.8 GPa (60 HRC), which increased to 13.1 GPa after coating. For sample C, the hardness increased from 5.6 GPa (54 HRC) to 12.5 GPa after coating, while sample D showed an increase in hardness from 4.9 GPa (49 HRC) to 12.3 GPa. Overall, the initial hardness values ​​of the samples ranged from 4 to 7 GPa, while the hardness values ​​significantly increased to 12-14 GPa after coating.

[0075] Table 2. Test results of nanoindentation

[0076] Corrosion resistance test The corrosion resistance tests in these examples followed the GB / T 10125 standard. The standard procedure for salt spray testing included: preparing the sample by washing and drying, placing it in a salt spray chamber, and exposing it to a continuous mist of a 5% sodium chloride solution at a specified temperature and humidity for a predetermined duration. After the exposure period, the sample was removed and evaluated for signs of corrosion such as rust formation and coating degradation to assess its corrosion resistance.

[0077] In the preliminary internal corrosion resistance evaluation, an Fe-31 protective coating (Fe 31 Cr 15 Mo 14 C 10 B 10 Si5Ti 15 The samples exhibited outstanding performance after 6 hours of exposure to a 5% sodium chloride corrosive solution, showing no visible signs of corrosion. After 24 hours of exposure, the samples maintained their structural integrity, demonstrating sustained protective effectiveness. Furthermore, in a third-party salt spray test conducted according to GB / T10125 standard, the samples coated with the Fe-31 protective coating maintained excellent condition even after 48 hours of exposure to a salt spray environment (e.g., ...). Figure 1(As shown). This performance verifies the effectiveness of the Fe-31 protective coating in improving corrosion resistance.

[0078] Adhesion test The adhesion test in this embodiment followed the Daimler-Benz Rockwell-C (HRC-DB) test standard. According to this standard, a 0.2 mm diameter conical indenter was used to apply a 1470 N load to the sample surface. During imaging, images were forced to be acquired at a consistent pixel size to ensure comparability. The indentation should be located near the center of the test image, and the scale bar was removed to maintain clarity. Furthermore, the minimum height or width of the image (whichever is smaller) should not be less than twice the diameter of the indentation to ensure sufficient resolution for analysis. The acquired images were compared with a standard reference image (…). Figure 2 Comparing the left and right images, coating adhesion can be classified into HF1, HF2, HF3, HF4, HF5, and HF6, with HF1 being the best and HF6 the worst. This provides a systematic framework for evaluating coating adhesion quality. Compared with the standard image, the protective coating's adhesion reaches the optimal level of the coating adhesion standard, HF=1. The results are as follows... Figure 2 As shown.

[0079] Sharpness and durability testing The sharpness test in this embodiment followed the ISO 8442-5:2004 standard. According to ISO 8442-5:2004, blade performance was measured by the distance the blade cut into the medium in each cycle, continuously tracked throughout the test. The blade needed to cut a sufficient amount of medium to complete the test. Two cutting performance indicators, ICP (Initial Cutting Performance) and CER (Cutting Edge Retention), were calculated based on accumulated data. ICP was measured by the depth of cut after three cuts, while CER was measured by the depth of cut after 200 cuts with the same cutting force. The ICP and CER of the bare blade were recorded as 16.61 mm and 72.57 mm, respectively; while the ICP and CER of the Fe-31 coated blade were recorded as 23.68 mm and 77 mm, respectively. The test results show that the sharpness and durability of the fruit knife with the protective coating are significantly improved.

[0080] Friction coefficient test The friction coefficient test in this embodiment was conducted according to the nano-scratch test procedure. Following this procedure, a nanoindenter was used to apply a controlled load to the sample surface through a sharp indenter, while simultaneously recording the lateral and normal forces. The friction coefficient was then calculated using the ratio of the lateral force to the normal load. The test results showed that the Fe-31 coating exhibited a friction coefficient of approximately 0.18, indicating a very smooth surface texture, which enhances its hardness and durability. The lower friction coefficient reduces heat generation during use, further extending the coating's lifespan by reducing wear.

[0081] Antibacterial performance test The antimicrobial tests in the examples followed ISO 22196. According to ISO 22196, the following values ​​were recorded: the common logarithmic mean (U0) of the number of viable bacteria recovered immediately after inoculation from untreated test samples; and the common logarithmic mean (U0) of the number of viable bacteria recovered 24 h after inoculation from untreated test samples. t The common logarithmic mean of the number of viable bacteria recovered from the treated test sample 24 h after inoculation (A) t Then the antibacterial activity R is calculated as: R = (U t − U0) − (A t − U0) = U t – A t The antibacterial rate is calculated as: (U t – A t ) / U t .

[0082] Test results show that the Fe-31 coating exhibits an antibacterial activity level (R) of 5.8 against Staphylococcus aureus, with an inhibition rate exceeding 99.99%; and an antibacterial activity level (R) of 6.1 against Escherichia coli, with an inhibition rate exceeding 99.99%. These test results indicate that the prepared coating has significant antibacterial properties against both Staphylococcus aureus and Escherichia coli.

[0083] Food-grade testing is crucial in blade applications to ensure safety, compliance, durability, hygiene, and effective performance during food processing. The food-grade testing was conducted according to US Food and Drug Administration (FDA) CFR 175.300, CPG 7117.05, and ICP-OES standards. First, chloroform extract was tested in 8% ethanol, water, and n-heptane, all below the limits. Second, soluble lead (Pb) was tested in 4% acetic acid, also meeting requirements. Third, the total chromium content percentage was 16.2%, meeting the requirement of greater than 10.5%. These food-grade test results demonstrate that the coating is safe for use in food-grade blade applications.

Claims

1. A method for forming a coating on a steel workpiece, comprising: (1) The steel workpiece is etched to obtain the etched steel workpiece; (2) Using the etched steel workpiece as the anode, electropolishing is performed on it to obtain an electropolished steel workpiece; (3) The electropolished steel workpiece is subjected to plasma treatment to obtain a plasma-treated steel workpiece; (4) An intermediate layer is deposited on the surface of the plasma-treated steel workpiece to obtain a steel workpiece with an intermediate layer; (5) Deposit an amorphous metal coating on the steel workpiece with the intermediate layer, wherein the amorphous metal coating is composed of an amorphous alloy selected from the following: zirconium-based amorphous alloy, copper-based amorphous alloy, nickel-based amorphous alloy, aluminum-based amorphous alloy, titanium-based amorphous alloy, iron-based amorphous alloy or palladium-based amorphous alloy.

2. The method according to claim 1, wherein the amorphous metal coating in (5) is composed of an iron-based amorphous alloy.

3. The method according to claim 2, wherein the iron-based amorphous alloy comprises 30-50 at.% Fe, 10-25 at.% Cr, 10-20 at.% Mo, 10-20 at.% Ti, 5-15 at.% B, 5-15 at.% C, 3-8 at.% Si, 0-10 at.% Co and 0-5 at.% Y.

4. The method according to claim 3, wherein the iron-based amorphous alloy is composed of Fe 31 Cr 15 Mo 14 C 10 B 10 Si5Ti 15 composition.

5. The method according to claim 3, wherein the iron-based amorphous alloy is composed of Fe 41 Cr 15 Co7Mo 14 C 12 Composed of B9Y2.

6. The method according to claim 3, wherein the iron-based amorphous alloy is composed of Fe 44 Cr 15 Mo 14 C 10 Composition: B5Si5Co7.

7. The method according to claim 3, wherein the iron-based amorphous alloy is composed of Fe 46 Cr 23 Mo 14 Composition: B5Si5Co7.

8. The method according to any one of claims 1-7, wherein the intermediate layer in (4) is composed of Cu, Al, Ti or TiO, preferably composed of Al or Ti, and most preferably composed of Ti.

9. The method according to any one of claims 1-8, wherein the etching process in (1) is carried out in an etching solution containing ferric chloride.

10. The method according to any one of claims 1-8, wherein the intermediate layer and the amorphous metal coating are deposited on the treated steel workpiece by physical vapor deposition (PVD), such as sputtering.

11. The method of claim 10, wherein the intermediate layer is deposited on the treated steel workpiece by radio frequency (RF) sputtering or direct current (DC) sputtering; preferably, the sputtering is performed in an argon atmosphere at 0.1-1 Pa and 2-4 W / cm² for 5-20 minutes; more preferably, the sputtering is performed in an argon atmosphere at 0.3 Pa and 2.55 W / cm² for 10 minutes.

12. The method of claim 10, wherein the amorphous metal coating is deposited on the treated steel workpiece by direct current (DC) sputtering; preferably, the DC sputtering is performed in an argon atmosphere at 0.1-1 Pa and 2-4 W / cm² for 40-100 minutes; more preferably, the DC sputtering is performed in an argon atmosphere at 0.3 Pa and 2.55 W / cm² for 60 minutes.

13. The method according to any one of claims 1-12, wherein the steel workpiece is a cutting tool, such as a blade.

14. A coated steel workpiece, comprising: steel base; The intermediate layer on the surface of the steel substrate; as well as The amorphous metal coating on the surface of the steel substrate with the intermediate layer; The coated steel workpiece is made by the method described in any one of claims 1-13.

15. The coated steel workpiece according to claim 14, wherein the thickness of the intermediate layer is 0-100 nm.

16. The coated steel workpiece according to claim 14 or 15, wherein the thickness of the amorphous metal coating is 100-900 nm.

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