Antioxidant coating and surface-modified metal material
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- IND TECH RES INST
- Filing Date
- 2025-03-06
- Publication Date
- 2026-05-29
AI Technical Summary
Existing metallic materials are prone to oxidation in high-temperature and warm-humidity environments, leading to a decline in performance. Furthermore, existing anti-oxidation coatings leave residues during high-temperature sintering, limiting their processing applications.
A coating layer of chlorinated, fluorinated, and alkyl-substituted poly(p-xylene) was used as an antioxidant coating, with a weight ratio of 1–10:6–27:2–15, and was formed on the surface of a metal material by chemical vapor deposition.
It effectively prevents metal materials from oxidizing at high temperatures, avoids coating residue, ensures stable material performance, and is suitable for subsequent processing.
Smart Images
Figure CN122104013A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an antioxidant coating and a surface-modified metallic material having said antioxidant coating. Background Technology
[0002] Most metallic materials exhibit high surface activity. In high-temperature, warm-humidity, electrochemical, and oxygen-containing environments, their surfaces readily absorb oxygen and moisture, leading to oxidation and corrosion, which degrades certain properties. For example, oxidation of the NdFeB material surface results in a decrease in magnetic properties. Therefore, NdFeB materials require vacuum or inert atmosphere protection throughout the entire preparation process, and an anti-oxidation coating must be applied immediately after preparation to prevent surface oxidation. Currently, a common method is to form Al, Zn, Ni, Cu, or their alloys on the surface of the metallic material, making it less prone to oxidation during storage after preparation and ensuring its performance.
[0003] Since the metal material needs to be processed or formed in the future, this coating must be removed by high temperature. However, if there are residues of the aforementioned anti-oxidation coating during the high-temperature sintering process, it will limit the processing application of the metal material. Summary of the Invention
[0004] According to an embodiment of the present invention, an antioxidant coating is provided. The antioxidant coating comprises: chlorinated parylene, fluorinated parylene, and alkyl-substituted parylene. The weight ratio of chlorine:fluorine:alkyl in the antioxidant coating is 1–10:6–27:2–15.
[0005] According to another embodiment of the present invention, a surface-modified metal material is provided. The surface-modified metal material comprises: a metal material body and a coating layer covering the surface of the metal material body. The coating layer is the aforementioned anti-oxidation coating. Attached Figure Description
[0006] Figure 1 This is a scanning electron microscope (SEM) image of the surface-modified NdFeB alloy powder from Experiment Example 2.
[0007] Figure 2 This is the thermogravimetric (TGA) curve of freshly produced NdFeB alloy powder without surface modification.
[0008] Figure 3 This is a differential thermal analysis (DTA) curve of the surface-modified NdFeB alloy powder prepared in Experimental Example 4. Detailed Implementation
[0009] The following provides many different embodiments for implementing various features of the invention. However, these embodiments are merely illustrative and are not intended to limit the scope and application of the invention.
[0010] An antioxidant coating is provided according to embodiments of the present disclosure. The antioxidant coating comprises: chlorinated parylene, fluorinated parylene, and alkyl-substituted parylene.
[0011] The weight ratio of chlorine:fluorine:alkyl in the antioxidant coating is 1–10:6–27:2–15. In some embodiments, the weight ratio of chlorine:fluorine:alkyl in the antioxidant coating is 1–8:6–25:2–10. In some embodiments, the weight ratio of chlorine:fluorine:alkyl in the antioxidant coating is 1–8:8–25:4–10.
[0012] In some embodiments, the alkyl group in the aforementioned alkyl-substituted parylene may be a C1-C6 straight-chain or branched alkyl group, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl, or 1,2-dimethylbutyl, or their isomers.
[0013] In some embodiments, the chlorinated poly(p-xylene) is Where n is an integer between 100 and 10000.
[0014] In some embodiments, the fluorinated poly(p-xylene) is Where n is an integer between 100 and 10000.
[0015] In some embodiments, the alkyl-substituted poly(p-xylene) is Where n is an integer between 100 and 10000.
[0016] According to the embodiments disclosed in this invention, the present invention provides a surface-modified metal material. The surface-modified metal material includes a metal material body and a coating layer covering the surface of the metal material body to prevent oxidation of the metal material body. The coating layer is the aforementioned anti-oxidation coating.
[0017] In some embodiments, the metal material body can be a metal material that is easily oxidized, such as an iron-containing metal material, an aluminum-containing metal material, a cobalt-containing metal material, a nickel-containing metal material, or a copper-containing metal material. Iron-containing metal materials can be, for example, neodymium iron boron or samarium iron nitrogen; aluminum-containing metal materials can be, for example, AlNiCo. The aforementioned metal materials can be, for example, pure metals or alloys.
[0018] In some embodiments, the weight ratio of the metal material body to the cladding layer may be 9 to 19, for example 10 to 17 or 10 to 15.
[0019] In some embodiments, the metal material body can be a powder with a particle size between 1 μm and 70 μm, for example, between 1 μm and 50 μm or between 1 μm and 20 μm. Metal material powders generally exhibit irregular shapes or tend to be flaky; therefore, "particle size" in this disclosure refers to the median diameter. The median diameter is the diameter of the particle at the 50% height of the cumulative distribution curve (number basis) of the particle size (also known as the D50 value). The smaller the particle size of the powder, the thinner the coating layer tends to be to avoid excessive impurities interfering with subsequent processing. In some embodiments, if the surface-modified metal material is NdFeB powder, the particle size of the resulting surface-modified NdFeB material can be between 2 μm and 80 μm, for example, between 2 μm and 50 μm or between 2 μm and 20 μm. The thickness of the coating layer is, for example, between 0.2 μm and 1.2 μm.
[0020] In other embodiments, the metal material body may be a block. The block may be, for example, a block formed by pressing metal powder into a block and then sintering it, and the block may have various shapes and sizes according to design requirements.
[0021] Based on the above, the surface-modified metal material of the present invention utilizes a poly(p-xylene) polymer to coat the metal material body, which not only effectively achieves the effect of anti-oxidation, but also utilizes the low boiling point of the polymer to achieve the effect of no polymer residue during high-temperature sintering.
[0022] The following are several experiments to verify the effectiveness of the present invention, but these experiments and their results are not intended to limit the scope of application of the present invention.
[0023] Metallic material raw materials:
[0024] 1. Pure neodymium, pure iron, and ferroborone (neodymium, iron, and boron in a weight ratio of approximately 30:69:1) are placed in a melting crucible and melted into a liquid using vacuum induction melting. The molten neodymium-iron-boron alloy is then rapidly solidified into thin sheets using strip casting. These sheets are then subjected to hydrogen absorption and air jet milling processes to form neodymium-iron-boron alloy powder. The resulting neodymium-iron-boron alloy powder has a particle size D50 of approximately 2–10 μm.
[0025] 2. Maximum Magnetic Energy Product Analysis of Unoxidized NdFeB Alloy Powder: Freshly produced NdFeB alloy powder was immediately processed into circular blocks with a diameter of 8-10 mm and a thickness of approximately 5 mm. Subsequent maximum magnetic energy product analysis showed a value of 350 kJ / m. 3 That is, the maximum magnetic energy product of freshly produced, unmodified NdFeB alloy powder is 350 kJ / m³. 3 .
[0026] 3. Maximum Magnetic Energy Product Analysis of Accelerated Oxidation NdFeB Alloy Powder: Freshly produced NdFeB alloy powder was placed in a constant temperature and humidity environment (85℃ / 85%) for 120 hours, then formed into bulk materials. Subsequent maximum magnetic energy product analysis revealed a maximum magnetic energy product of 203 kJ / m². 3 Therefore, as can be seen from the previous analysis, the magnetic properties of the bulk material will be affected by the high degree of surface oxidation and corrosion of the unmodified NdFeB powder after being subjected to a constant temperature and humidity environment. Its maximum magnetic energy product loss rate reaches -42% (=(203-350) / 350×100%).
[0027] Antioxidant coating material for the coating layer:
[0028] 1. Raw material for chlorinated parylenes: parylene C dimer (purchased from Jingming Chemical, product name dichloro-p-cyclophane).
[0029] 2. Raw material for fluorinated parylenes: parylene F dimer (purchased from Jingming Chemical, product name α-Perfluorodi-p-xylene).
[0030] 3. Raw material for alkyl-substituted parylene: parylene AM-2 dimer (purchased from Jingming Chemical, product name α,α'-dimethoxy-p-xylene).
[0031] <Experimental Examples 1-6> Surface-modified NdFeB alloy materials were prepared by vapor phase chemical deposition.
[0032] The vapor phase chemical deposition (VPD) film formation process involves first placing the antioxidant coating material into an evaporation chamber. The amounts of coating material used in Examples 1-6 are shown in Table 1 below. Then, freshly produced NdFeB alloy powder is placed into the deposition chamber, and the entire reaction apparatus is evacuated. Next, the temperature of the pyrolysis furnace is controlled at 680-700°C, and the vapor chamber is heated to 150°C. This causes the antioxidant coating material to evaporate into a gas, which is then sent to the pyrolysis furnace to be pyrolyzed into monomers. These monomers are then sent to the deposition chamber at room temperature, where they polymerize and deposit on the surface of the NdFeB alloy powder, resulting in the surface-modified NdFeB alloy materials obtained in Examples 1-6. The entire VPD film formation process takes approximately one hour.
[0033] <Comparative Examples 1-3>
[0034] Using the same preparation method as the above experimental examples, but with the antioxidant coating raw material replaced by a single component from Table 2, surface-modified NdFeB materials as prepared in Comparative Examples 1-3 were obtained.
[0035] <Comparative Examples 4-14>
[0036] Using the same preparation method as the above experimental examples, but with the antioxidant coating raw materials prepared according to the components and amounts in Table 3, the surface-modified NdFeB materials prepared in Comparative Examples 4 to 14 were obtained.
[0037] <Analysis Method>
[0038] 1. Thickness
[0039] The particle size D50 of the final product was obtained using SEM (JEOL-manufactured JSM-6330TF). For example... Figure 1 The image shown is a SEM image of the surface-modified NdFeB material in Experimental Example 2. The NdFeB alloy powder exhibits an irregular shape, while the anti-oxidation coating on the surface of the NdFeB powder has a roughly uniform thickness, ranging from 814.3 nm to 651.4 nm. The measured anti-oxidation coating thickness D50 of Experimental Example 2 is 0.74 μm.
[0040] 2. Decomposition temperature
[0041] Thermogravimetric analysis (TGA 2 manufactured by Mettler Toledo) was used to measure the sample. The sample was placed in a permeable, process-controlled heating and cooling furnace, air was introduced, and the sample was heated from room temperature to 400°C. The change in sample weight over temperature and time was recorded. For example... Figure 2 The displayed curve is the TGA curve of freshly produced NdFeB alloy powder without an anti-oxidation coating. Figure 2It was observed that the weight of the newly produced NdFeB alloy powder sample without an anti-oxidation coating increased positively throughout the testing process, indicating that NdFeB powder without an anti-oxidation coating is easily oxidized, causing its weight to increase with temperature.
[0042] Thermogravimetric analysis (TGA) can also be used to measure the DTA curve, and the decomposition temperature of the coating layer in the sample can be obtained from the changes in the DTA curve. For example... Figure 3 The figure shows the DTA changes of the surface-modified NdFeB composite material prepared in Experimental Example 4. There is a significant endothermic peak at 360°C, indicating that the coating layer of Experimental Example 4 decomposes at this temperature. Subsequently, the DTA curve of NdFeB will increase again due to oxidation.
[0043] 3. Constant temperature and humidity test
[0044] The sample was placed in an environment with a temperature of 85℃ and a humidity of 85% for 120 hours.
[0045] 4. Maximum magnetic energy product
[0046] Each sample (powder) that has undergone the above constant temperature and humidity test is made into a round block with a diameter of 8-10 mm and a thickness of about 5 mm. Then, according to the IEC 60404-5 magnetic test method for permanent magnet (hard magnet) materials, the hysteresis curve of the aforementioned block is measured using a vibrating sample magnetometer (VSM).
[0047] The VSM cavity contains a fixed-direction electromagnet with a magnetic field strength ranging from 0 to 3T, a temperature range from 50K to 400K, and a magnetic field resolution of 10. -6 emu. When the block vibrates inside the cavity, it has different magnetization intensities under different magnetic fields. By measuring the degree of change of magnetic field lines through an induction coil and converting it into an induced voltage, the magnetic moment of the block can be measured. The maximum magnetic energy product can be obtained by dividing the block volume by the magnetic moment.
[0048] The results obtained from the above analysis of the raw materials used in all experimental and comparative examples and the surface-modified NdFeB composite materials are listed in Tables 1 to 3 below.
[0049] Table 1
[0050]
[0051] In Table 1, C represents Parylene C raw material dichloro-p-cyclophane; AM2 represents Parylene AM-2 raw material α,α'-dimethoxy-p-xylene; and F represents Parylene F raw material α-Perfluorodi-p-xylene.
[0052] As shown in Table 1, Experimental Examples 1-6 of the present invention, by adjusting the proportions of chlorine, fluorine, and alkyl groups in the vapor deposition formulation, can produce surface-modified NdFeB composite materials with good water and gas barrier effects, thin vapor deposition thickness, and low decomposition temperature. Specifically, the surface-modified NdFeB alloy materials prepared in Experimental Examples 1-6 have a strength greater than 300 kJ / m³. 3 The maximum magnetic energy product and the coating thickness is less than 1.2 μm.
[0053] Table 2
[0054]
[0055] As can be seen from Table 2, the surface-modified NdFeB composite materials with a single-component coating layer (Comparative Examples 1-3) have problems such as excessively high decomposition temperature or small maximum magnetic energy product.
[0056] Table 3
[0057]
[0058] In Table 3, C represents Parylene C raw material dichloro-p-cyclophane; AM2 represents Parylene AM-2 raw material α,α'-dimethoxy-p-xylene; and F represents Parylene F raw material α-Perfluorodi-p-xylene.
[0059] The surface-modified NdFeB composite materials prepared in Comparative Examples 7-9 and 12 were not measured for subsequent magnetic energy product because the coating thickness was too high, which was not conducive to subsequent processing and use.
[0060] Table 3 shows that the surface-modified NdFeB alloy materials prepared by Comparative Examples 4-6 with a coating layer lacking alkyl-substituted parylene generally have a low maximum magnetic energy product; the surface-modified NdFeB alloy materials prepared by Comparative Examples 7-9 with a coating layer lacking fluorine-substituted parylene generally have a large coating layer thickness; the surface-modified NdFeB alloy materials prepared by Comparative Examples 10 and 11 with a coating layer lacking chlorine-substituted parylene have a low maximum magnetic energy product and a slightly higher decomposition temperature than other samples. The surface-modified NdFeB alloy material prepared by Comparative Example 12 with a coating layer lacking chlorine-substituted parylene and having a low fluorine-substituted parylene content has a large coating layer thickness. The surface-modified NdFeB alloy material prepared by Comparative Example 13 with a coating layer containing excessive chlorine-substituted parylene has both a large coating layer thickness and a low maximum magnetic energy product. Comparative Example 14, which uses a coating layer with a low alkyl-substituted poly(p-xylene) content, results in a surface-modified NdFeB alloy material with a low maximum energy product.
[0061] <Experimental Example 7>
[0062] Freshly produced NdFeB powder was pressed into compacts with a diameter of 14 mm and a height of 15 mm, and aligned under a magnetic field of up to 2 Tesla. Subsequently, cold isothermal pressing (CIP) was performed at a pressure of 300 MPa. The compacts were then subjected to 10... -3 NdFeB bulk material was obtained by sintering at 1060℃ for 4 hours under vacuum of Pa.
[0063] Then, using the coating composition and vapor deposition method of Experimental Example 2, a coating layer was formed on the surface of the NdFeB bulk material.
[0064] The above analysis yielded a coating thickness of 0.72 μm and a decomposition temperature of 340 °C. After constant temperature and humidity testing, the maximum magnetic energy product was 338 kJ / m². 3 Therefore, since the NdFeB body is a bulk NdFeB material, the coating layer can also effectively achieve the effect of anti-oxidation.
[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. An antioxidant coating, characterized in that, include: Chlorinated parylene, fluorinated parylene, and alkyl-substituted parylene, and The weight ratio of chlorine:fluorine:alkyl in the antioxidant coating is 1-10:6-27:2-15.
2. The antioxidant coating according to claim 1, characterized in that, The alkyl group is a C1-C6 straight-chain or branched alkyl group.
3. The antioxidant coating according to claim 1, characterized in that, The weight ratio of chlorine:fluorine:alkyl in the antioxidant coating is 1-8:6-25:2-10.
4. The antioxidant coating according to claim 1, characterized in that, The chlorinated poly(p-xylene) is Where n is an integer between 100 and 10000.
5. The antioxidant coating according to claim 1, characterized in that, The fluorinated poly(p-xylene) is Where n is an integer between 100 and 10000.
6. The antioxidant coating according to claim 1, characterized in that, The alkyl-substituted poly(p-xylene) is Where n is an integer between 100 and 10000.
7. A surface-modified metallic material, characterized in that, include: Metal material body; as well as A coating layer is applied to the surface of the metal material body, wherein the coating layer is an anti-oxidation coating according to any one of claims 1 to 6.
8. The surface-modified metallic material according to claim 7, characterized in that, The material body is made of a metal or alloy containing iron, aluminum, cobalt, nickel, or copper.
9. The surface-modified metallic material according to claim 8, characterized in that, The metal material body is neodymium iron boron, aluminum nickel cobalt, or samarium iron nitrogen.
10. The surface-modified metallic material according to claim 7, characterized in that, The metal material body is a powder material with a particle size D50 between 1μm and 80μm.
11. The surface-modified metallic material according to claim 7, characterized in that, The thickness of the coating layer is between 0.2 μm and 1.2 μm.