Electromagnetically pure iron material coated with a wear-resistant coating and a heat treatment method

Abstract

The application discloses a kind of electromagnetic pure iron material and heat treatment method of surface coating wear-resistant coating, through vacuum heat treatment process under hydrogen, nitrogen condition, not only can prevent electromagnetic pure iron surface oxidation after coating, simultaneously reduce the adverse effects of electromagnetic pure iron caused by coating process under high temperature condition, such as abnormal grain growth, structure deformation, internal stress increase, which leads to the serious decline of electromagnetic pure iron magnetic properties;Effectively improve the coercive force, maximum permeability and other magnetic properties of electromagnetic pure iron material after coating, and can maintain the high hardness and strong wear resistance of electromagnetic pure iron after coating, finally obtain electromagnetic pure iron material with good magnetic properties, high hardness and strong wear resistance, further expand its application field. The pressure of hydrogen and nitrogen in the vacuum heat treatment furnace is kept constant, so that the surface of the electromagnetic pure iron coated with wear-resistant coating is in vacuum reduction condition, the coating will not oxidize, stress concentration, etc., thereby ensuring that the hardness and wear resistance of the coating will not decrease.

Description

Technical Field

[0001] This invention belongs to the field of heat treatment technology for soft magnetic materials, and relates to an electromagnetic pure iron material with a wear-resistant coating on its surface and a heat treatment method thereon. Background Technology

[0002] The main chemical component of industrial electromagnetic pure iron is iron. It is a high-quality steel with an iron content of over 99.5% and low carbon, sulfur, and phosphorus content. It has a high saturation magnetic induction intensity Bs and magnetic permeability H, low coercivity Hc, good cold and hot working performance, low price, and simple heat treatment process. It is widely used as a component of solenoid valves, such as the shell, valve core, and moving iron core, in industries such as electrical appliances, telecommunications, electronics, and defense.

[0003] However, the alloy element content in electromagnetic pure iron is almost zero, resulting in extremely low hardness and poor wear and corrosion resistance. Surface coating with TiN wear-resistant coating is an effective way to improve the hardness and wear and corrosion resistance of electromagnetic pure iron. However, because the high-hardness, excellent wear-resistant and corrosion-resistant TiN coating process is often completed under high-temperature conditions (chemical vapor deposition process, temperature 900-1000℃), although this coating improves the hardness and wear and corrosion resistance of electromagnetic pure iron, it easily causes grain growth and increased stress, leading to severe damage to its magnetic properties, such as a sharp increase in coercivity and a significant decrease in maximum magnetic flux. Therefore, it is impossible to achieve a balance between hardness, wear and corrosion resistance, and magnetic properties.

[0004] Studies have shown that metal heat treatment processes can eliminate internal stress in materials and prevent structural deformation, making them an effective means of restoring the magnetic properties of electromagnetic pure iron materials. However, existing heat treatment processes only meet the requirements for restoring the magnetic properties of electromagnetic pure iron materials treated under low-temperature conditions such as surface nitriding and nickel plating. Due to the lower process temperatures, surface nitriding and nickel plating cause relatively little damage to the magnetic properties of electromagnetic pure iron materials. In contrast, surface coating with wear-resistant coatings, due to the higher temperatures, severely damages the magnetic properties, and correspondingly effective heat treatment processes have not yet been reported.

[0005] Therefore, in response to the problem that the magnetic properties of electromagnetic pure iron materials coated with wear-resistant coatings on the surface decrease significantly under current high-temperature conditions, there is an urgent need in this field to develop a heat treatment process that can effectively improve the magnetic properties of electromagnetic pure iron materials coated with wear-resistant coatings. This would allow the coated electromagnetic pure iron materials to achieve a balance of hardness, corrosion and wear resistance, and magnetic properties, thereby extending the service life of electromagnetic pure iron materials and further expanding their application range. Summary of the Invention

[0006] The purpose of this invention is to solve the problem that the magnetic properties of electromagnetic pure iron materials are severely damaged due to the high temperature of the surface-coated wear-resistant coating, resulting in a significant decrease in the magnetic properties of the materials. This invention provides an electromagnetic pure iron material with a surface-coated wear-resistant coating and a heat treatment method.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] The present invention proposes a heat treatment method for electromagnetic pure iron materials with a surface coated with a wear-resistant coating, comprising the following steps:

[0009] Electromagnetic pure iron with a wear-resistant coating on its surface is placed into a heating device;

[0010] A protective gas is introduced into the heating device, and heating, heat preservation, and cooling are carried out in sequence.

[0011] Once the temperature in the heating device drops to the set temperature, the protective gas supply is stopped. After the temperature in the heating device cools down to room temperature, electromagnetic pure iron material is obtained.

[0012] Preferably, the wear-resistant coating is a TiN coating, which is prepared by chemical vapor deposition.

[0013] Preferably, the heating device is a vacuum heat treatment furnace, and the vacuum degree of the vacuum heat treatment furnace is 10. -1 Pa~10 -2 Pa.

[0014] Preferably, the protective gases are hydrogen and nitrogen; the hydrogen flow rate is 450 sccm to 700 sccm, and the nitrogen flow rate is 450 sccm to 700 sccm.

[0015] Preferably, the heating and heat preservation process is as follows: the temperature in the heating device is raised to 500℃ to 550℃ at a rate of 3℃ / min to 7℃ / min, and then raised to 720℃ to 820℃ at a heating rate of 2℃ / min to 6℃ / min, and a first heat preservation is performed for 30min to 60min; after the first heat preservation, the temperature is raised to 860℃ to 900℃ at a heating rate of 2℃ / min to 6℃ / min, and a second heat preservation is performed for 3.5h to 6h.

[0016] Preferably, the cooling process is as follows: after the second heat preservation is completed, the temperature inside the heating device is reduced to 650℃~700℃ at a cooling rate of 0.5℃ / min~1.5℃ / min; then it is reduced to 450℃~500℃ at a cooling rate of 3℃ / min~5℃ / min, and then cooled to 100℃~150℃ by furnace cooling, and the protective gas is stopped.

[0017] Preferably, the pressure inside the heating device is 2300Pa to 5000Pa.

[0018] Preferably, the pressure of the protective gas in the heating device is constant.

[0019] Preferably, the heat-treated electromagnetic pure iron has a hardness of 1500HV to 1700HV, a friction coefficient of 0.30 to 0.35 for the wear-resistant coating, a coercivity of 22.5A / m to 25.4A / m for the wear-resistant coating, and a magnetic permeability of 14.5mH / m to 16.3mH / m for the wear-resistant coating.

[0020] The present invention proposes an electromagnetic pure iron material, which is prepared by heat treatment of electromagnetic pure iron material with a surface coated with a wear-resistant coating.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention proposes a heat treatment method for electromagnetic pure iron materials with a wear-resistant coating. The method involves placing the wear-resistant coated electromagnetic pure iron into a heating device to prevent surface oxidation after coating and to mitigate the adverse effects of abnormal grain growth and increased internal stress caused by the high-temperature coating process, which can lead to a significant decrease in the magnetic properties of the electromagnetic pure iron. Through a unique heat treatment process design during heating and cooling, the internal stress of the wear-resistant coated electromagnetic pure iron is effectively reduced, thereby significantly restoring the coercivity, maximum permeability, and other magnetic properties of the coated electromagnetic pure iron material. Furthermore, the high hardness and strong wear resistance of the coated electromagnetic pure iron are maintained, ultimately obtaining an electromagnetic pure iron material with excellent magnetic properties, high hardness, and strong wear resistance, further expanding its application areas.

[0023] Furthermore, high vacuum conditions can prevent the wear-resistant coating on the surface of electromagnetic pure iron from oxidizing, and prevent oxygen from penetrating into the electromagnetic pure iron matrix and causing matrix oxidation, which would negatively affect the magnetic properties of the electromagnetic pure iron.

[0024] Furthermore, the presence of a protective gas can make the electromagnetic pure iron material heat up more uniformly; heating it to a certain temperature at a certain heating rate and holding it at that temperature, and then further increasing the temperature and holding it at that temperature, can make the grains grow fully and uniformly, further reduce the internal stress, further improve the soft magnetic properties, further reduce the coercivity and further increase the maximum permeability.

[0025] Furthermore, the slow heating and holding at high temperature in the high-temperature section allows the internal stress of the wear-resistant coating on the surface of the electromagnetic pure iron to be fully released. At the same time, it makes the internal structure of the electromagnetic pure iron more balanced, reduces the internal stress to a minimum, further reduces the coercivity, and increases the maximum permeability to a maximum value.

[0026] Furthermore, slow cooling can prevent stress concentration and coating cracking on the surface coating of electromagnetic pure iron caused by rapid cooling; at the same time, it can prevent drastic changes in the internal structure of electromagnetic pure iron, and the structural changes are stable and slow, so that its magnetic properties are minimized.

[0027] Furthermore, the accelerated cooling rate in the low-temperature section can prevent lattice distortion and reduced magnetic properties caused by dispersion strengthening due to the precipitation of dispersed phases in the matrix; at the same time, it can quickly bring the stress state of the wear-resistant coating on the surface into balance with the stress state of the electromagnetic pure iron substrate, thereby minimizing the impact on the magnetic properties of the electromagnetic pure iron.

[0028] Furthermore, by maintaining a constant pressure of hydrogen and nitrogen in the vacuum heat treatment furnace, the surface of the electromagnetic pure iron coated with a wear-resistant coating is kept under vacuum reduction conditions. This prevents oxidation and stress concentration of the coating, ensuring that the hardness and wear resistance of the coating are not reduced. Thus, the electromagnetic pure iron material coated with a wear-resistant coating achieves a balance between hardness, wear resistance, and magnetic properties. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A flowchart illustrating the heat treatment method for electromagnetic pure iron materials with a wear-resistant coating applied to their surface, as described in this invention.

[0031] Figure 2 This is a schematic diagram of the heat treatment process curve of Embodiment 1 of the present invention.

[0032] Figure 3 This is a hardness test diagram of the electromagnetic pure iron material in Embodiment 1 of the present invention.

[0033] Figure 4 This is a test diagram of the friction coefficient of the electromagnetic pure iron material in Embodiment 1 of the present invention.

[0034] Figure 5 This is a coercivity test diagram of the electromagnetic pure iron material in Embodiment 1 of the present invention.

[0035] Figure 6 This is a test diagram of the maximum magnetic permeability of the electromagnetic pure iron material in Embodiment 1 of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0038] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0039] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0040] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0042] As used in this article, the term "electromagnetic pure iron" refers to a high-quality steel with an iron content of over 99.5%, which is a low-carbon, low-sulfur, and low-phosphorus iron. The corresponding national standard is GB6983-2008 Electromagnetic Pure Iron.

[0043] As used herein, the terms “comprising,” “including,” and “containing” are interchangeable and include not only closed definitions but also semi-closed and open definitions. In other words, the terms include “consisting of” and “substantially consisting of”.

[0044] As used in this article, the term "vacuum heat treatment furnace" refers to a device used to perform heat treatments such as normalizing, annealing, tempering, and reheating on metallic materials in a vacuum environment.

[0045] As used in this article, the term "coercivity" refers to the magnetic field that, after a magnetic material has been saturated with magnetization, can be reduced to zero by applying a magnetic field of a certain magnitude in the opposite direction of the original magnetization field. This magnetic field is called the coercive magnetic field, also known as coercivity, and is symbolized as Hc.

[0046] As used in this article, the term "maximum permeability" refers to the maximum permeability at each point on the basic magnetization curve, denoted by μm.

[0047] As used in this article, the term "sccm" is a volumetric flow rate unit, which stands for standard-state cubic centimeter per minute.

[0048] As used in this article, the term "protective gas" refers to a gas with a purity of 99.99%.

[0049] The present invention will now be described in further detail with reference to the accompanying drawings:

[0050] This invention proposes a heat treatment method for electromagnetic pure iron materials with a surface coated with a wear-resistant coating, such as... Figure 1 As shown, it includes the following steps:

[0051] Step 1: Place the electromagnetic pure iron with a wear-resistant coating on its surface into the heating device;

[0052] The wear-resistant coating is a TiN coating, which is prepared by chemical vapor deposition.

[0053] The heating device is a vacuum heat treatment furnace, and the vacuum degree of the vacuum heat treatment furnace is 10. -1 Pa~10 -2 Pa.

[0054] The protective gases are hydrogen and nitrogen; the hydrogen flow rate is 450 sccm to 700 sccm, and the nitrogen flow rate is 450 sccm to 700 sccm.

[0055] Step 2: Introduce protective gas into the heating device and perform heating, heat preservation, and cooling treatments in sequence;

[0056] The heating and heat preservation process is as follows: The temperature in the heating device is increased to 500℃~550℃ at a rate of 3℃ / min~7℃ / min, and then increased to 720℃~820℃ at a heating rate of 2℃ / min~6℃ / min and heat preservation is carried out for the first time for 30min~60min; after the first heat preservation, the temperature is increased to 860℃~900℃ at a heating rate of 2℃ / min~6℃ / min and heat preservation is carried out for the second time for 3.5h~6h.

[0057] The cooling process is as follows: After the second heat preservation is completed, the temperature inside the heating device is reduced to 650℃~700℃ at a cooling rate of 0.5℃ / min~1.5℃ / min; then it is reduced to 450℃~500℃ at a cooling rate of 3℃ / min~5℃ / min, and then cooled to 100℃~150℃ by furnace cooling, and the protective gas is stopped.

[0058] Step 3: When the temperature in the heating device drops to the set temperature, stop the supply of protective gas and wait for the temperature in the heating device to cool to room temperature to obtain electromagnetic pure iron material.

[0059] The pressure inside the heating device is 2300Pa to 5000Pa.

[0060] The pressure of the protective gas in the heating device is constant.

[0061] The heat-treated electromagnetic pure iron has a hardness of 1500HV to 1700HV, a friction coefficient of 0.30-0.35 for the wear-resistant coating, a coercivity of 22.5A / m to 25.4A / m for the wear-resistant coating, and a magnetic permeability of 14.5mH / m to 16.3mH / m.

[0062] Example 1

[0063] S1, The electromagnetic pure iron material with a CVD TiN wear-resistant coating is placed into a vacuum heat treatment furnace. The vacuum system is turned on to pre-evacuate the furnace to a vacuum degree of 10. -1 Pa; High vacuum conditions can prevent the wear-resistant coating on the surface of electromagnetic pure iron from oxidizing, and prevent oxygen from penetrating into the electromagnetic pure iron matrix and causing matrix oxidation, which would have a negative impact on the magnetic properties of electromagnetic pure iron.

[0064] S2, 500 sccm of hydrogen and 450 sccm of nitrogen protective gases are introduced respectively to maintain the pressure inside the vacuum heat treatment furnace at 2300 Pa; the heating program is started and the temperature is increased to 500℃ at a rate of 3℃ / min; the presence of protective gases can make the electromagnetic pure iron material heat more uniformly; the heating rate in the low-temperature section is faster, the grain growth rate is faster, the grain boundaries are reduced, the stress is reduced, and the coercivity is reduced; then the temperature is increased to 720℃ at a heating rate of 2℃ / min and held for 30 min; further increasing the temperature and holding it can make the grain growth sufficient and uniform, further reduce the internal stress, further improve the soft magnetic properties, further reduce the coercivity, and further increase the maximum permeability.

[0065] S3, after the heat preservation is completed, the temperature is raised to 860℃ at a heating rate of 2℃ / min and kept at that temperature for 3.5h. The high-temperature section is slowly heated and kept at that temperature, which can fully release the internal stress of the wear-resistant coating on the surface of the electromagnetic pure iron. At the same time, the internal structure of the electromagnetic pure iron is more balanced, the internal stress is reduced to the minimum, the coercivity is further reduced, and the maximum permeability is increased to the maximum value.

[0066] S4. After the heat preservation is completed, the temperature is reduced to 650℃ at a cooling rate of 0.5℃ / min. Slow cooling can prevent stress concentration and coating cracking on the surface coating of electromagnetic pure iron caused by rapid cooling. At the same time, it can prevent drastic changes in the internal structure of electromagnetic pure iron. The structural changes are stable and slow, and the impact on its magnetic properties is minimized.

[0067] S5, then cool down to 450℃ at 3℃ / min; the accelerated cooling rate in the low-temperature section can prevent lattice distortion and reduced magnetic properties caused by dispersion strengthening due to the precipitation of dispersed phase in the matrix; at the same time, it can quickly bring the stress state of the wear-resistant coating on the surface into balance with the stress state of the electromagnetic pure iron on the substrate, thereby minimizing the impact on the magnetic properties of the electromagnetic pure iron.

[0068] S6, after cooling to 450℃, is cooled to 100℃ using a furnace-based cooling method. The introduction of hydrogen and nitrogen is stopped until it cools to room temperature, resulting in an electromagnetic pure iron material with a wear-resistant coating after heat treatment. The pressure of hydrogen and nitrogen in the vacuum heat treatment furnace is maintained constant, ensuring the surface of the electromagnetic pure iron with the wear-resistant coating is under vacuum reduction conditions. This prevents oxidation and stress concentration in the coating, thus ensuring that the hardness and wear resistance of the coating are not reduced. This achieves a balance between hardness, wear resistance, and magnetic properties in the electromagnetic pure iron material with the wear-resistant coating.

[0069] Tests: The hardness, coefficient of friction, and magnetic properties of the heat-treated electromagnetic pure iron material with a wear-resistant coating obtained in Example 1 were compared with those of the same electromagnetic pure iron material without heat treatment but with a wear-resistant coating. The results are as follows. Figure 2-6 As shown. Figure 2This is a schematic diagram of the heat treatment process curve for electromagnetic pure iron materials. The heat treatment process, under certain vacuum conditions and with hydrogen and nitrogen as protective gases, includes controllable heating, holding, and cooling processes.

[0070] Hardness test:

[0071] Method: The hardness of an electromagnetic pure iron material with a wear-resistant coating after heat treatment obtained in Example 1 was compared with that of the same electromagnetic pure iron material with a wear-resistant coating but without heat treatment.

[0072] Coating hardness test method: The hardness was tested using an MVS-1000D1 digital display microhardness tester with a diamond indenter, a load of 300mN, and a holding pressure of 10s. Eight points were measured and the average value was taken.

[0073] Result: As Figure 3 The hardness of the electromagnetic pure iron material with a wear-resistant coating on its surface obtained after heat treatment is 1700 HV.

[0074] Friction performance test:

[0075] Method: The frictional properties of an electromagnetic pure iron material with a wear-resistant coating after heat treatment obtained in Example 1 were compared with those of the same electromagnetic pure iron material with a wear-resistant coating but without heat treatment.

[0076] Friction performance testing method: The wear resistance of the samples was tested using an Rtec friction and wear testing machine. The test mode was as follows: the samples were subjected to bidirectional linear unlubricated reciprocating friction in the XY direction at room temperature using 6mm SiC grinding balls. The specific test parameters were: normal load 5-20N, friction speed 20mm / s, friction distance 5mm, time 20min, and frequency 2Hz. Each sample was tested 3 times, and the average value of the results was taken.

[0077] Result: As Figure 4 The friction coefficient of the electromagnetic pure iron material with a wear-resistant coating after heat treatment is 0.30.

[0078] Magnetic property test:

[0079] Method: The magnetic properties (coercivity Hc, maximum permeability μm) of an electromagnetic pure iron material with a wear-resistant coating on its surface after heat treatment obtained in Example 1 were compared with those of the same electromagnetic pure iron material with a wear-resistant coating on its surface but without heat treatment.

[0080] Magnetic property testing method: The coercivity Hc and maximum permeability μm of electromagnetic pure iron material with a wear-resistant coating on the surface after heat treatment are tested using a magnetic property tester.

[0081] Result: As Figure 5The coercivity Hc of the electromagnetic pure iron material with a wear-resistant coating after heat treatment is shown to be 22.5 A / m.

[0082] like Figure 6 The maximum magnetic permeability μm of the electromagnetic pure iron material with a wear-resistant coating after heat treatment is shown to be 16.3 mH / m.

[0083] Example 2

[0084] S1, The electromagnetic pure iron material with a CVD TiN wear-resistant coating is placed into a vacuum heat treatment furnace. The vacuum system is turned on to pre-evacuate the furnace to a vacuum degree of 10. -1 Pa; High vacuum conditions can prevent the wear-resistant coating on the surface of electromagnetic pure iron from oxidizing, and prevent oxygen from penetrating into the electromagnetic pure iron matrix and causing matrix oxidation, which would have a negative impact on the magnetic properties of electromagnetic pure iron.

[0085] S2, 600 sccm of hydrogen and 400 sccm of nitrogen protective gases are introduced respectively to maintain the pressure inside the vacuum heat treatment furnace at 3000 Pa; the heating program is started and the temperature is increased to 520℃ at a rate of 4℃ / min; the presence of protective gases can make the electromagnetic pure iron material heat more uniformly; the heating rate in the low-temperature section is faster, the grain growth rate is faster, the grain boundaries are reduced, the stress is reduced, and the coercivity is reduced; then the temperature is increased to 770℃ at a heating rate of 3℃ / min and held for 35 min; further increasing the temperature and holding it can make the grain growth sufficient and uniform, further reduce the internal stress, further improve the soft magnetic properties, further reduce the coercivity, and further increase the maximum permeability.

[0086] S3, after the heat preservation is completed, the temperature is raised to 870℃ at a heating rate of 3℃ / min and kept at that temperature for 4 hours; the high temperature section is slowly heated and kept at that temperature, which can fully release the internal stress of the wear-resistant coating on the surface of the electromagnetic pure iron, while making the internal structure of the electromagnetic pure iron more balanced, reducing the internal stress to the minimum, further reducing the coercivity, and increasing the maximum permeability to the maximum value.

[0087] S4. After the heat preservation is completed, the temperature is reduced to 670℃ at a cooling rate of 0.7℃ / min. Slow cooling can prevent stress concentration and coating cracking on the surface coating of electromagnetic pure iron caused by rapid cooling. At the same time, it can prevent drastic changes in the internal structure of electromagnetic pure iron. The structural changes are stable and slow, and the impact on its magnetic properties is minimized.

[0088] S5, then cool down to 470℃ at 5℃ / min; the accelerated cooling rate in the low-temperature section can prevent lattice distortion and reduced magnetic properties caused by dispersion strengthening due to the precipitation of dispersed phase in the matrix; at the same time, it can quickly bring the stress state of the wear-resistant coating on the surface into balance with the stress state of the electromagnetic pure iron on the substrate, thereby minimizing the impact on the magnetic properties of the electromagnetic pure iron.

[0089] S6, after cooling to 470℃, is cooled to 100℃ using a furnace-based cooling method. The introduction of hydrogen and nitrogen is stopped until it cools to room temperature, resulting in an electromagnetic pure iron material with a wear-resistant coating after heat treatment. The pressure of hydrogen and nitrogen in the vacuum heat treatment furnace is maintained constant, ensuring the surface of the wear-resistant coated electromagnetic pure iron is under vacuum reduction conditions. This prevents oxidation and stress concentration in the coating, thus ensuring that the hardness and wear resistance of the coating are not reduced. This achieves a balance between hardness, wear resistance, and magnetic properties in the electromagnetic pure iron material with the wear-resistant coating.

[0090] The results show that the hardness of the electromagnetic pure iron coated with the wear-resistant coating after heat treatment is 1500 HV; the coefficient of friction of the coating is 0.35; the coercivity Hc of the coating is 25.4 A / m; and the maximum permeability μm of the coating is 14.5 mH / m.

[0091] Example 3

[0092] S1, The electromagnetic pure iron material with a CVD TiN wear-resistant coating is placed into a vacuum heat treatment furnace. The vacuum system is turned on to pre-evacuate the furnace to a vacuum degree of 10. -1 Pa; High vacuum conditions can prevent the wear-resistant coating on the surface of electromagnetic pure iron from oxidizing, and prevent oxygen from penetrating into the electromagnetic pure iron matrix and causing matrix oxidation, which would have a negative impact on the magnetic properties of electromagnetic pure iron.

[0093] S2, 550 sccm of hydrogen and 500 sccm of nitrogen protective gases are introduced respectively to maintain the pressure inside the vacuum heat treatment furnace at 2500 Pa; the heating program is started and the temperature is increased to 530℃ at a rate of 5℃ / min; the presence of protective gases can make the electromagnetic pure iron material heat more uniformly; the heating rate in the low-temperature section is faster, the grain growth rate is faster, the grain boundaries are reduced, the stress is reduced, and the coercivity is reduced; then the temperature is increased to 780℃ at a heating rate of 5℃ / min and held for 35 min; further increasing the temperature and holding it can make the grain growth sufficient and uniform, further reduce the internal stress, further improve the soft magnetic properties, further reduce the coercivity, and further increase the maximum permeability.

[0094] S3, after the heat preservation is completed, the temperature is raised to 880℃ at a heating rate of 4℃ / min and kept at that temperature for 4 hours; the high temperature section is slowly heated and kept at that temperature, which can fully release the internal stress of the wear-resistant coating on the surface of the electromagnetic pure iron, while making the internal structure of the electromagnetic pure iron more balanced, reducing the internal stress to the minimum, further reducing the coercivity, and increasing the maximum permeability to the maximum value.

[0095] S4. After the heat preservation is completed, the temperature is reduced to 680℃ at a cooling rate of 0.8℃ / min. Slow cooling can prevent stress concentration and coating cracking on the surface coating of electromagnetic pure iron caused by rapid cooling. At the same time, it can prevent drastic changes in the internal structure of electromagnetic pure iron. The structural changes are stable and slow, and the impact on its magnetic properties is minimized.

[0096] S5, then cool down to 480℃ at 4℃ / min; the accelerated cooling rate in the low-temperature section can prevent lattice distortion and reduced magnetic properties caused by dispersion strengthening due to the precipitation of dispersed phase in the matrix; at the same time, it can quickly bring the stress state of the wear-resistant coating on the surface into balance with the stress state of the electromagnetic pure iron on the substrate, thereby minimizing the impact on the magnetic properties of the electromagnetic pure iron.

[0097] S6, after cooling to 480℃, is cooled to 120℃ using a furnace-based cooling method. The introduction of hydrogen and nitrogen is stopped until it cools to room temperature, resulting in an electromagnetic pure iron material with a wear-resistant coating after heat treatment. The pressure of hydrogen and nitrogen in the vacuum heat treatment furnace is maintained constant, ensuring the surface of the electromagnetic pure iron with the wear-resistant coating is under vacuum reduction conditions. This prevents oxidation and stress concentration in the coating, thus ensuring that the hardness and wear resistance of the coating are not reduced. This achieves a balance between hardness, wear resistance, and magnetic properties in the electromagnetic pure iron material with the wear-resistant coating.

[0098] The results show that the hardness of the electromagnetic pure iron coated with the wear-resistant coating after heat treatment is 1593 HV; the coefficient of friction of the coating is 0.34; the coercivity Hc of the coating is 25.1 A / m; and the maximum permeability μm of the coating is 14.9 mH / m.

[0099] Example 4

[0100] S1, The electromagnetic pure iron material with a CVD TiN wear-resistant coating is placed into a vacuum heat treatment furnace. The vacuum system is turned on to pre-evacuate the furnace to a vacuum degree of 10. -1 Pa; High vacuum conditions can prevent the wear-resistant coating on the surface of electromagnetic pure iron from oxidizing, and prevent oxygen from penetrating into the electromagnetic pure iron matrix and causing matrix oxidation, which would have a negative impact on the magnetic properties of electromagnetic pure iron.

[0101] S2, 600 sccm of hydrogen and 550 sccm of nitrogen protective gases are introduced respectively to maintain the pressure inside the vacuum heat treatment furnace at 3000 Pa; the heating program is started and the temperature is increased to 550℃ at a rate of 5℃ / min; the presence of protective gases can make the electromagnetic pure iron material heat more uniformly; the heating rate in the low-temperature section is faster, the grain growth rate is faster, the grain boundaries are reduced, the stress is reduced, and the coercivity is reduced; then the temperature is increased to 800℃ at a heating rate of 5℃ / min and held for 35 min; further increasing the temperature and holding it can make the grain growth sufficient and uniform, further reduce the internal stress, further improve the soft magnetic properties, further reduce the coercivity, and further increase the maximum permeability.

[0102] S3, after the heat preservation is completed, the temperature is raised to 900℃ at a heating rate of 4℃ / min and kept at that temperature for 4 hours; the high temperature section is slowly heated and kept at that temperature, which can fully release the internal stress of the wear-resistant coating on the surface of the electromagnetic pure iron, while making the internal structure of the electromagnetic pure iron more balanced, reducing the internal stress to the minimum, further reducing the coercivity, and increasing the maximum permeability to the maximum value.

[0103] S4. After the heat preservation is completed, the temperature is reduced to 690℃ at a cooling rate of 1.2℃ / min. Slow cooling can prevent stress concentration and coating cracking on the surface coating of electromagnetic pure iron caused by rapid cooling. At the same time, it can prevent drastic changes in the internal structure of electromagnetic pure iron. The structural changes are stable and slow, and the impact on its magnetic properties is minimized.

[0104] S5, then cool down to 500℃ at 4℃ / min; the accelerated cooling rate in the low-temperature section can prevent lattice distortion and reduced magnetic properties caused by dispersion strengthening due to the precipitation of dispersed phase in the matrix; at the same time, it can quickly bring the stress state of the wear-resistant coating on the surface into balance with the stress state of the electromagnetic pure iron on the substrate, thereby minimizing the impact on the magnetic properties of the electromagnetic pure iron.

[0105] S6, after cooling to 500℃, is cooled to 120℃ using a furnace-based cooling method. The introduction of hydrogen and nitrogen is stopped until it cools to room temperature, resulting in an electromagnetic pure iron material with a wear-resistant coating after heat treatment. The pressure of hydrogen and nitrogen in the vacuum heat treatment furnace is maintained constant, ensuring the surface of the wear-resistant coated electromagnetic pure iron is under vacuum reduction conditions. This prevents oxidation and stress concentration in the coating, thus ensuring that the hardness and wear resistance of the coating are not reduced. This achieves a balance between hardness, wear resistance, and magnetic properties in the electromagnetic pure iron material with the wear-resistant coating.

[0106] The results show that the hardness of the electromagnetic pure iron coated with the wear-resistant coating after heat treatment is 1579 HV; the coefficient of friction of the coating is 0.32; the coercivity Hc of the coating is 24.7 A / m; and the maximum permeability μm of the coating is 15.1 mH / m.

[0107] Example 5

[0108] S1, The electromagnetic pure iron material with a CVD TiN wear-resistant coating is placed into a vacuum heat treatment furnace. The vacuum system is turned on to pre-evacuate the furnace to a vacuum degree of 10. -1 Pa; High vacuum conditions can prevent the wear-resistant coating on the surface of electromagnetic pure iron from oxidizing, and prevent oxygen from penetrating into the electromagnetic pure iron matrix and causing matrix oxidation, which would have a negative impact on the magnetic properties of electromagnetic pure iron.

[0109] S2, 700 sccm of hydrogen and 600 sccm of nitrogen protective gases are introduced respectively to maintain the pressure inside the vacuum heat treatment furnace at 4000 Pa; the heating program is started and the temperature is increased to 550℃ at a rate of 7℃ / min; the presence of protective gases can make the electromagnetic pure iron material heat more uniformly; the heating rate in the low-temperature section is faster, the grain growth rate is faster, the grain boundaries are reduced, the stress is reduced, and the coercivity is reduced; then the temperature is increased to 820℃ at a heating rate of 5℃ / min and held for 60 min; further increasing the temperature and holding it can make the grain growth sufficient and uniform, further reduce the internal stress, further improve the soft magnetic properties, further reduce the coercivity, and further increase the maximum permeability.

[0110] S3, after the heat preservation is completed, the temperature is raised to 900℃ at a heating rate of 6℃ / min and kept at that temperature for 6 hours; the high temperature section is slowly heated and kept at that temperature, which can fully release the internal stress of the wear-resistant coating on the surface of the electromagnetic pure iron, while making the internal structure of the electromagnetic pure iron more balanced, reducing the internal stress to the minimum, further reducing the coercivity, and increasing the maximum permeability to the maximum value.

[0111] S4. After the heat preservation is completed, the temperature is reduced to 680℃ at a cooling rate of 1.5℃ / min. Slow cooling can prevent stress concentration and coating cracking on the surface coating of electromagnetic pure iron caused by rapid cooling. At the same time, it can prevent drastic changes in the internal structure of electromagnetic pure iron. The structural changes are stable and slow, and the impact on its magnetic properties is minimized.

[0112] S5, then cool down to 460℃ at 5℃ / min; the accelerated cooling rate in the low-temperature section can prevent lattice distortion and reduced magnetic properties caused by dispersion strengthening due to the precipitation of dispersed phase in the matrix; at the same time, it can quickly bring the stress state of the wear-resistant coating on the surface into balance with the stress state of the electromagnetic pure iron on the substrate, thereby minimizing the impact on the magnetic properties of the electromagnetic pure iron.

[0113] S6, after cooling to 500℃, is cooled to 150℃ using a furnace-based cooling method. The introduction of hydrogen and nitrogen is then stopped until it cools to room temperature, resulting in an electromagnetic pure iron material with a wear-resistant coating after heat treatment. The pressure of hydrogen and nitrogen in the vacuum heat treatment furnace is maintained constant, ensuring that the surface of the electromagnetic pure iron with the wear-resistant coating is under vacuum reduction conditions. This prevents oxidation and stress concentration in the coating, thus ensuring that the hardness and wear resistance of the coating are not reduced. This achieves a balance between hardness, wear resistance, and magnetic properties in the electromagnetic pure iron material with the wear-resistant coating.

[0114] The results show that the hardness of the electromagnetic pure iron coated with the wear-resistant coating after heat treatment is 1660 HV; the coefficient of friction of the coating is 0.32; the coercivity Hc of the coating is 23.5 A / m; and the maximum permeability μm of the coating is 15.5 mH / m.

[0115] Example 6

[0116] S1, The electromagnetic pure iron material with a CVD TiN wear-resistant coating is placed into a vacuum heat treatment furnace. The vacuum system is turned on to pre-evacuate the furnace to a vacuum degree of 10. -2 Pa; High vacuum conditions can prevent the wear-resistant coating on the surface of electromagnetic pure iron from oxidizing, and prevent oxygen from penetrating into the electromagnetic pure iron matrix and causing matrix oxidation, which would have a negative impact on the magnetic properties of electromagnetic pure iron.

[0117] S2, 600 sccm of hydrogen and 700 sccm of nitrogen protective gases are introduced respectively to maintain the pressure inside the vacuum heat treatment furnace at 2000 Pa; the heating program is started and the temperature is increased to 500℃ at a rate of 3℃ / min; the presence of protective gases can make the electromagnetic pure iron material heat more uniformly; the heating rate in the low-temperature section is faster, the grain growth rate is faster, the grain boundaries are reduced, the stress is reduced, and the coercivity is reduced; then the temperature is increased to 720℃ at a heating rate of 6℃ / min and held for 20 min; further increasing the temperature and holding it can make the grain growth sufficient and uniform, further reduce the internal stress, further improve the soft magnetic properties, further reduce the coercivity, and further increase the maximum permeability.

[0118] S3, after the heat preservation is completed, the temperature is raised to 860℃ at a heating rate of 3℃ / min and kept at that temperature for 3 hours; the high-temperature section is slowly heated and kept at that temperature, which can fully release the internal stress of the wear-resistant coating on the surface of the electromagnetic pure iron, while making the internal structure of the electromagnetic pure iron more balanced, reducing the internal stress to the minimum, further reducing the coercivity, and increasing the maximum permeability to the maximum value.

[0119] S4. After the heat preservation is completed, the temperature is reduced to 700℃ at a cooling rate of 0.5℃ / min. Slow cooling can prevent stress concentration and coating cracking on the surface coating of electromagnetic pure iron caused by rapid cooling. At the same time, it can prevent drastic changes in the internal structure of electromagnetic pure iron. The structural changes are stable and slow, and the impact on its magnetic properties is minimized.

[0120] S5, then cool down to 450℃ at 3℃ / min; the accelerated cooling rate in the low-temperature section can prevent lattice distortion and reduced magnetic properties caused by dispersion strengthening due to the precipitation of dispersed phase in the matrix; at the same time, it can quickly bring the stress state of the wear-resistant coating on the surface into balance with the stress state of the electromagnetic pure iron on the substrate, thereby minimizing the impact on the magnetic properties of the electromagnetic pure iron.

[0121] S6, after cooling to 450℃, is cooled to 100℃ using a furnace-based cooling method. The introduction of hydrogen and nitrogen is stopped until it cools to room temperature, resulting in an electromagnetic pure iron material with a wear-resistant coating after heat treatment. The pressure of hydrogen and nitrogen in the vacuum heat treatment furnace is maintained constant, ensuring the surface of the electromagnetic pure iron with the wear-resistant coating is under vacuum reduction conditions. This prevents oxidation and stress concentration in the coating, thus ensuring that the hardness and wear resistance of the coating are not reduced. This achieves a balance between hardness, wear resistance, and magnetic properties in the electromagnetic pure iron material with the wear-resistant coating.

[0122] The results show that the hardness of the electromagnetic pure iron coated with the wear-resistant coating after heat treatment is 1675 HV; the coefficient of friction of the coating is 0.33; the coercivity Hc of the coating is 23.2 A / m; and the maximum permeability μm of the coating is 15.6 mH / m.

[0123] Example 7

[0124] S1, The electromagnetic pure iron material with a CVD TiN wear-resistant coating is placed into a vacuum heat treatment furnace. The vacuum system is turned on to pre-evacuate the furnace to a vacuum degree of 10. -2 Pa; High vacuum conditions can prevent the wear-resistant coating on the surface of electromagnetic pure iron from oxidizing, and prevent oxygen from penetrating into the electromagnetic pure iron matrix and causing matrix oxidation, which would have a negative impact on the magnetic properties of electromagnetic pure iron.

[0125] S2, 700 sccm of hydrogen and 500 sccm of nitrogen protective gases are introduced respectively to maintain the pressure inside the vacuum heat treatment furnace at 2500 Pa; the heating program is started and the temperature is increased to 520℃ at a rate of 4℃ / min; the presence of protective gases can make the electromagnetic pure iron material heat more uniformly; the heating rate in the low-temperature section is faster, the grain growth rate is faster, the grain boundaries are reduced, the stress is reduced, and the coercivity is reduced; then the temperature is increased to 770℃ at a heating rate of 3℃ / min and held for 35 min; further increasing the temperature and holding it can make the grain growth sufficient and uniform, further reduce the internal stress, further improve the soft magnetic properties, further reduce the coercivity, and further increase the maximum permeability.

[0126] S3, after the heat preservation is completed, the temperature is raised to 870℃ at a heating rate of 4℃ / min and kept at that temperature for 4 hours; the high temperature section is slowly heated and kept at that temperature, which can fully release the internal stress of the wear-resistant coating on the surface of the electromagnetic pure iron, while making the internal structure of the electromagnetic pure iron more balanced, reducing the internal stress to the minimum, further reducing the coercivity, and increasing the maximum permeability to the maximum value.

[0127] S4. After the heat preservation is completed, the temperature is reduced to 690℃ at a cooling rate of 0.7℃ / min. Slow cooling can prevent stress concentration and coating cracking on the surface coating of electromagnetic pure iron caused by rapid cooling. At the same time, it can prevent drastic changes in the internal structure of electromagnetic pure iron. The structural changes are stable and slow, and the impact on its magnetic properties is minimized.

[0128] S5, then cool down to 470℃ at 3℃ / min; the cooling rate in the low-temperature section is accelerated, which can prevent lattice distortion and magnetic performance reduction caused by dispersion strengthening effect due to the precipitation of dispersed phase in the matrix; at the same time, it can quickly bring the stress state of the surface wear-resistant coating to a balance with the stress state of the electromagnetic pure iron of the substrate, thereby minimizing the impact on the magnetic performance of the electromagnetic pure iron.

[0129] S6, after cooling to 470℃, is cooled to 120℃ using a furnace-based cooling method. The introduction of hydrogen and nitrogen is stopped until it cools to room temperature, resulting in an electromagnetic pure iron material with a wear-resistant coating after heat treatment. The pressure of hydrogen and nitrogen in the vacuum heat treatment furnace is maintained constant, ensuring the surface of the wear-resistant coated electromagnetic pure iron is under vacuum reduction conditions. This prevents oxidation and stress concentration in the coating, thus ensuring that the hardness and wear resistance of the coating are not reduced. This achieves a balance between hardness, wear resistance, and magnetic properties in the electromagnetic pure iron material with the wear-resistant coating.

[0130] The results show that the hardness of the electromagnetic pure iron coated with the wear-resistant coating after heat treatment is 1682 HV; the coefficient of friction of the coating is 0.34; the coercivity Hc of the coating is 24.4 A / m; and the maximum permeability μm of the coating is 15.2 mH / m.

[0131] Example 8

[0132] S1, The electromagnetic pure iron material with a CVD TiN wear-resistant coating is placed into a vacuum heat treatment furnace. The vacuum system is turned on to pre-evacuate the furnace to a vacuum degree of 10. -2 Pa; High vacuum conditions can prevent the wear-resistant coating on the surface of electromagnetic pure iron from oxidizing, and prevent oxygen from penetrating into the electromagnetic pure iron matrix and causing matrix oxidation, which would have a negative impact on the magnetic properties of electromagnetic pure iron.

[0133] S2, 600 sccm of hydrogen and 700 sccm of nitrogen protective gases are introduced respectively to maintain the pressure inside the vacuum heat treatment furnace at 3000 Pa; the heating program is started and the temperature is increased to 530℃ at a rate of 5℃ / min; the presence of protective gases can make the electromagnetic pure iron material heat more uniformly; the heating rate in the low-temperature section is faster, the grain growth rate is faster, the grain boundaries are reduced, the stress is reduced, and the coercivity is reduced; then the temperature is increased to 790℃ at a heating rate of 5℃ / min and held for 45 min; further increasing the temperature and holding it can make the grain growth sufficient and uniform, further reduce the internal stress, further improve the soft magnetic properties, further reduce the coercivity, and further increase the maximum permeability.

[0134] S3, after the heat preservation is completed, the temperature is raised to 880℃ at a heating rate of 5℃ / min and kept at that temperature for 5 hours; the high-temperature section is slowly heated and kept at that temperature, which can fully release the internal stress of the wear-resistant coating on the surface of the electromagnetic pure iron, while making the internal structure of the electromagnetic pure iron more balanced, reducing the internal stress to the minimum, further reducing the coercivity, and increasing the maximum permeability to the maximum value.

[0135] S4. After the heat preservation is completed, the temperature is reduced to 680℃ at a cooling rate of 1.0℃ / min. Slow cooling can prevent stress concentration and coating cracking on the surface coating of electromagnetic pure iron caused by rapid cooling. At the same time, it can prevent drastic changes in the internal structure of electromagnetic pure iron. The structural changes are stable and slow, and the impact on its magnetic properties is minimized.

[0136] S5, then cool down to 490℃ at 4℃ / min; the accelerated cooling rate in the low-temperature section can prevent lattice distortion and reduced magnetic properties caused by dispersion strengthening due to the precipitation of dispersed phase in the matrix; at the same time, it can quickly bring the stress state of the wear-resistant coating on the surface into balance with the stress state of the electromagnetic pure iron on the substrate, thereby minimizing the impact on the magnetic properties of the electromagnetic pure iron.

[0137] S6, after cooling to 490℃, is further cooled to 130℃ using a furnace-based cooling method. The introduction of hydrogen and nitrogen is then stopped until it cools to room temperature, resulting in an electromagnetic pure iron material with a wear-resistant coating after heat treatment. The pressure of hydrogen and nitrogen in the vacuum heat treatment furnace is maintained constant, ensuring that the surface of the electromagnetic pure iron with the wear-resistant coating is under vacuum reduction conditions. This prevents oxidation and stress concentration in the coating, thus ensuring that the hardness and wear resistance of the coating are not reduced. This achieves a balance between hardness, wear resistance, and magnetic properties in the electromagnetic pure iron material with the wear-resistant coating.

[0138] The results show that the hardness of the electromagnetic pure iron coated with the wear-resistant coating after heat treatment is 1688 HV; the coefficient of friction of the coating is 0.32; the coercivity Hc of the coating is 23.1 A / m; and the maximum permeability μm of the coating is 15.7 mH / m.

[0139] Example 9

[0140] S1, The electromagnetic pure iron material with a CVD TiN wear-resistant coating is placed into a vacuum heat treatment furnace. The vacuum system is turned on to pre-evacuate the furnace to a vacuum degree of 10. -2 Pa; High vacuum conditions can prevent the wear-resistant coating on the surface of electromagnetic pure iron from oxidizing, and prevent oxygen from penetrating into the electromagnetic pure iron matrix and causing matrix oxidation, which would have a negative impact on the magnetic properties of electromagnetic pure iron.

[0141] S2, 500 sccm of hydrogen and 800 sccm of nitrogen protective gases are introduced respectively to maintain the pressure inside the vacuum heat treatment furnace at 4000 Pa; the heating program is started and the temperature is increased to 540℃ at a rate of 6℃ / min; the presence of protective gases can make the electromagnetic pure iron material heat more uniformly; the heating rate in the low-temperature section is faster, the grain growth rate is faster, the grain boundaries are reduced, the stress is reduced, and the coercivity is reduced; then the temperature is increased to 810℃ at a heating rate of 5℃ / min and held for 50 min; further increasing the temperature and holding it can make the grain growth sufficient and uniform, further reduce the internal stress, further improve the soft magnetic properties, further reduce the coercivity, and further increase the maximum permeability.

[0142] S3, after the heat preservation is completed, the temperature is raised to 890℃ at a heating rate of 5℃ / min and kept at that temperature for 4 hours; the high temperature section is slowly heated and kept at that temperature, which can fully release the internal stress of the wear-resistant coating on the surface of the electromagnetic pure iron, while making the internal structure of the electromagnetic pure iron more balanced, reducing the internal stress to the minimum, further reducing the coercivity, and increasing the maximum permeability to the maximum value.

[0143] S4. After the heat preservation is completed, the temperature is reduced to 670℃ at a cooling rate of 1.3℃ / min. Slow cooling can prevent stress concentration and coating cracking on the surface coating of electromagnetic pure iron caused by rapid cooling. At the same time, it can prevent drastic changes in the internal structure of electromagnetic pure iron. The structural changes are stable and slow, and the impact on its magnetic properties is minimized.

[0144] S5, then cool down to 460℃ at 4℃ / min; the accelerated cooling rate in the low-temperature section can prevent lattice distortion and reduced magnetic properties caused by dispersion strengthening due to the precipitation of dispersed phase in the matrix; at the same time, it can quickly bring the stress state of the wear-resistant coating on the surface into balance with the stress state of the electromagnetic pure iron on the substrate, thereby minimizing the impact on the magnetic properties of the electromagnetic pure iron.

[0145] S6, after cooling to 460℃, is cooled to 130℃ using a furnace-based cooling method. The introduction of hydrogen and nitrogen is stopped until it cools to room temperature, resulting in an electromagnetic pure iron material with a wear-resistant coating after heat treatment. The pressure of hydrogen and nitrogen in the vacuum heat treatment furnace is maintained constant, ensuring the surface of the electromagnetic pure iron with the wear-resistant coating is under vacuum reduction conditions. This prevents oxidation and stress concentration in the coating, thus ensuring that the hardness and wear resistance of the coating are not reduced. This achieves a balance between hardness, wear resistance, and magnetic properties in the electromagnetic pure iron material with the wear-resistant coating.

[0146] The results show that the hardness of the electromagnetic pure iron coated with the wear-resistant coating after heat treatment is 1684 HV; the coefficient of friction of the coating is 0.33; the coercivity Hc of the coating is 23.2 A / m; and the maximum permeability μm of the coating is 15.8 mH / m.

[0147] Example 10

[0148] S1, The electromagnetic pure iron material with a CVD TiN wear-resistant coating is placed into a vacuum heat treatment furnace. The vacuum system is turned on to pre-evacuate the furnace to a vacuum degree of 10. -2 Pa; High vacuum conditions can prevent the wear-resistant coating on the surface of electromagnetic pure iron from oxidizing, and prevent oxygen from penetrating into the electromagnetic pure iron matrix and causing matrix oxidation, which would have a negative impact on the magnetic properties of electromagnetic pure iron.

[0149] S2, 600 sccm of hydrogen and 900 sccm of nitrogen protective gases are introduced respectively to maintain the pressure inside the vacuum heat treatment furnace at 5000 Pa; the heating program is started and the temperature is increased to 550℃ at a rate of 7℃ / min; the presence of protective gases can make the electromagnetic pure iron material heat more uniformly; the heating rate in the low-temperature section is faster, the grain growth rate is faster, the grain boundaries are reduced, the stress is reduced, and the coercivity is reduced; then the temperature is increased to 820℃ at a heating rate of 6℃ / min and held for 60 min; further increasing the temperature and holding it can make the grain growth sufficient and uniform, further reduce the internal stress, further improve the soft magnetic properties, further reduce the coercivity, and further increase the maximum permeability.

[0150] S3, after the heat preservation is completed, the temperature is raised to 900℃ at a heating rate of 6℃ / min and kept at that temperature for 6 hours; the high temperature section is slowly heated and kept at that temperature, which can fully release the internal stress of the wear-resistant coating on the surface of the electromagnetic pure iron, while making the internal structure of the electromagnetic pure iron more balanced, reducing the internal stress to the minimum, further reducing the coercivity, and increasing the maximum permeability to the maximum value.

[0151] S4. After the heat preservation is completed, the temperature is reduced to 650℃ at a cooling rate of 1.5℃ / min. Slow cooling can prevent stress concentration and coating cracking on the surface coating of electromagnetic pure iron caused by rapid cooling. At the same time, it can prevent drastic changes in the internal structure of electromagnetic pure iron. The structural changes are stable and slow, and the impact on its magnetic properties is minimized.

[0152] S5, then cool down to 500℃ at 5℃ / min; the accelerated cooling rate in the low-temperature section can prevent lattice distortion and reduced magnetic properties caused by dispersion strengthening due to the precipitation of dispersed phase in the matrix; at the same time, it can quickly bring the stress state of the wear-resistant coating on the surface into balance with the stress state of the electromagnetic pure iron on the substrate, thereby minimizing the impact on the magnetic properties of the electromagnetic pure iron.

[0153] S6, after cooling to 500℃, is cooled to 150℃ using a furnace-based cooling method. The introduction of hydrogen and nitrogen is then stopped until it cools to room temperature, resulting in an electromagnetic pure iron material with a wear-resistant coating after heat treatment. The pressure of hydrogen and nitrogen in the vacuum heat treatment furnace is maintained constant, ensuring that the surface of the electromagnetic pure iron with the wear-resistant coating is under vacuum reduction conditions. This prevents oxidation and stress concentration in the coating, thus ensuring that the hardness and wear resistance of the coating are not reduced. This achieves a balance between hardness, wear resistance, and magnetic properties in the electromagnetic pure iron material with the wear-resistant coating.

[0154] The results show that the hardness of the electromagnetic pure iron coated with the wear-resistant coating after heat treatment is 1689 HV; the coefficient of friction of the coating is 0.32; the coercivity Hc of the coating is 23.0 A / m; and the maximum permeability μm of the coating is 15.9 mH / m.

[0155] Comparative Examples 1-5

[0156] An electromagnetic pure iron material with a surface-coated wear-resistant coating was prepared using a heat treatment process different from that in Example 1.

[0157] Electromagnetic pure iron materials with wear-resistant coatings as described in Comparative Examples 1-5 were prepared using a method similar to that of Example 1, except for the changes in parameters during the coating preparation process as shown in Table 1. The hardness, coefficient of friction, and magnetic properties of the materials were then measured.

[0158] Table 1 shows electromagnetic pure iron materials with surface-coated wear-resistant coatings that differ from the heat treatment process in Example 1.

[0159]

[0160] As can be seen from Table 1, the hardness of the electromagnetic pure iron material with a wear-resistant coating prepared by the heat treatment process used in the examples (the material hardness in Example 2 is 1500 HV) is significantly greater than the hardness of the electromagnetic pure iron material with a wear-resistant coating in Comparative Examples 1-5 (such as the material hardness in Comparative Example 5, which is 1270 HV).

[0161] As can be seen from Table 1, the coefficient of friction of the electromagnetic pure iron material with a wear-resistant coating prepared by the heat treatment process used in the examples (the coefficient of friction of the material in Example 2 is 0.35) is significantly less than the hardness of the electromagnetic pure iron material with a wear-resistant coating in Comparative Examples 1-5 (such as the coefficient of friction of the material in Comparative Example 1 is 0.41).

[0162] As can be seen from Table 1, the coercivity of the electromagnetic pure iron material with a wear-resistant coating prepared by the heat treatment process used in the examples (Hc = 25.4 A / m in Example 2) is significantly less than that of the electromagnetic pure iron material with a wear-resistant coating in Comparative Examples 1-5 (e.g., Hc = 29.5 A / m in Comparative Example 1).

[0163] As can be seen from Table 1, the maximum magnetic permeability of the electromagnetic pure iron material with a wear-resistant coating prepared by the heat treatment process used in the examples (material μm = 14.5 mH / m in Example 2) is significantly greater than the maximum magnetic permeability of the electromagnetic pure iron material with a wear-resistant coating in Comparative Examples 1-5 (e.g., material μm = 12.7 mH / m in Comparative Example 3).

[0164] Therefore, compared with Comparative Examples 1-5, the electromagnetic pure iron material with a wear-resistant coating prepared by the heat treatment process described in Example 1 of the present invention has excellent hardness, friction resistance and magnetic properties.

[0165] The present invention discloses a heat treatment method for electromagnetic pure iron materials with a wear-resistant coating. Through a vacuum heat treatment process under hydrogen and nitrogen conditions, this method not only prevents oxidation of the electromagnetic pure iron surface after coating but also reduces the adverse effects of abnormal grain growth, structural deformation, and increased internal stress caused by the high-temperature coating process, which can lead to a severe decrease in the magnetic properties of the electromagnetic pure iron. This method effectively improves the coercivity, maximum permeability, and other magnetic properties of the coated electromagnetic pure iron material while maintaining its high hardness and strong wear resistance. Ultimately, it yields an electromagnetic pure iron material with excellent magnetic properties, high hardness, and strong wear resistance, further expanding its application areas.

[0166] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A heat treatment method for electromagnetic pure iron material with a surface coated with a wear-resistant coating, characterized in that, Includes the following steps: Electromagnetic pure iron with a wear-resistant coating on its surface is placed into a heating device; A protective gas is introduced into the heating device, and heating, heat preservation, and cooling are carried out in sequence. When the temperature in the heating device drops to the set temperature, the protective gas supply is stopped, and the temperature in the heating device is allowed to cool to room temperature to obtain electromagnetic pure iron material. The heating and heat preservation process is as follows: the temperature in the heating device is increased to 500℃~550℃ at a rate of 3℃ / min~7℃ / min, then increased to 720℃~820℃ at a heating rate of 2℃ / min~6℃ / min and heat preservation is carried out for the first time for 30min~60min; after the first heat preservation, the temperature is increased to 860℃~900℃ at a heating rate of 2℃ / min~6℃ / min and heat preservation is carried out for the second time for 3.5h~6h; the wear-resistant coating is a TiN coating, which is prepared by chemical vapor deposition.

2. The heat treatment method for electromagnetic pure iron material with a wear-resistant coating on its surface according to claim 1, characterized in that, The heating device is a vacuum heat treatment furnace, and the vacuum degree of the vacuum heat treatment furnace is 10. -1 Pa ~10 -2 Pa.

3. The heat treatment method for electromagnetic pure iron material with a wear-resistant coating on its surface according to claim 1, characterized in that, The protective gases are hydrogen and nitrogen; the hydrogen flow rate is 450 sccm ~ 700 sccm, and the nitrogen flow rate is 450 sccm ~ 700 sccm.

4. The heat treatment method for electromagnetic pure iron material with a wear-resistant coating on its surface according to claim 1, characterized in that, The cooling process is as follows: After the second heat preservation is completed, the temperature inside the heating device is reduced to 650℃~700℃ at a cooling rate of 0.5℃ / min~1.5℃ / min; then it is reduced to 450℃~500℃ at a cooling rate of 3℃ / min~5℃ / min, and then cooled to 100℃~150℃ by furnace cooling, and the protective gas is stopped.

5. The heat treatment method for electromagnetic pure iron material with a wear-resistant coating on its surface according to claim 1, characterized in that, The pressure inside the heating device is 2300Pa~5000Pa.

6. The heat treatment method for electromagnetic pure iron material with a wear-resistant coating on its surface according to claim 1, characterized in that, The pressure of the protective gas in the heating device is constant.

7. The heat treatment method for electromagnetic pure iron material with a wear-resistant coating on its surface according to claim 1, characterized in that, The heat-treated electromagnetic pure iron has a hardness of 1500 HV ~ 1700 HV, a friction coefficient of 0.30-0.35 for the wear-resistant coating, a coercivity of 22.5 A / m ~ 25.4 A / m for the wear-resistant coating, and a magnetic permeability of 14.5 mH / m ~ 16.3 mH / m.

8. An electromagnetically pure iron material, characterized in that, The electromagnetic pure iron material with a surface-coated wear-resistant coating, as described in any one of claims 1 to 7, was prepared by heat treatment.

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