A method for preparing a surface-hardened zirconium material sphere, a zirconium material sphere and application

Abstract

The application discloses a surface-hardened zirconium material sphere preparation method and the zirconium material sphere and application, wherein the preparation method comprises the following steps: firstly, annealing treatment is performed on a zirconium material raw material and rough machining is performed; then, high-temperature stress relief annealing is performed on the rough-machined sphere blank; after the stress relief annealing is completed, the sphere surface is polished, ultrasonic cleaning, anhydrous ethanol cleaning and drying are sequentially performed; finally, the sphere is placed into an ion nitriding furnace to perform ion nitriding, so that a finished product of the surface-hardened zirconium material sphere is obtained. The surface hardness of the zirconium material sphere prepared by the method disclosed by the application is significantly improved, the wear resistance is greatly enhanced, when the zirconium material sphere is applied to preparation of a ball valve sphere, the deformation of the ball valve sphere can be effectively controlled, the sealing performance is guaranteed, the ball valve sphere can meet the use requirements of light load, wear resistance and corrosion resistance working conditions, and the service life is prolonged.

Description

Technical Field

[0001] This application relates to the field of zirconium material surface treatment technology, and in particular to a method for preparing surface-hardened zirconium spheres, as well as the zirconium spheres and their applications. Background Technology

[0002] Zirconium and zirconium alloys possess moderate density and excellent corrosion resistance in most inorganic acids, organic acids, strong alkalis, and molten salts. They also exhibit good comprehensive mechanical properties, processability, and thermal conductivity, making them extremely important corrosion-resistant materials in the chemical industry. In the production of MMA, acetic acid, and other chemicals, zirconium materials have become the preferred material for equipment.

[0003] However, in practical applications, the low hardness, poor wear resistance, and tendency to clump together of zirconium often lead to surface wear on zirconium products, affecting their functionality. For example, when zirconium is used in the manufacture of valve cores, it can easily result in short valve life, poor precision, and unsatisfactory operational stability. Therefore, improving the surface hardness of zirconium and enhancing its wear resistance is of great significance for extending its service life, ensuring the stable operation of workpieces made from it, and broadening its application range.

[0004] Currently, there is limited research on technologies to improve the surface hardness and wear resistance of zirconium materials, mainly focusing on surface heating oxidation and thermal spraying. While these methods can increase the surface hardness of zirconium products, they either have low bonding strength with the substrate material, leading to easy coating peeling, or are difficult to implement for large-sized workpieces.

[0005] In summary, there is a need for a more ideal surface treatment technology for zirconium materials and their products to enhance their practical application value and effectiveness. Summary of the Invention

[0006] This application provides a method for preparing a surface-hardened zirconium sphere, which solves the problems of unstable effects caused by easy peeling of the hardened coating in current processes for improving the surface hardness of zirconium materials, and the difficulty in applying the method to large workpieces. It achieves excellent and stable surface hardening effect, long service life of the workpiece, and the ability to fully adapt to high-intensity working environments. This application also discloses a zirconium sphere obtained according to the above preparation method, and a ball valve using the zirconium sphere.

[0007] According to a first aspect of the embodiments of this application, a method for preparing surface-hardened zirconium spheres is provided, comprising the following steps:

[0008] S1. Heat the zirconium material to 700~750℃, hold it at the same temperature for 1~3 hours, and then remove it from the furnace and air cool it.

[0009] S2. Process the cooled zirconium material to obtain a spherical blank;

[0010] S3. The spherical blank is heated to 500°C at a rate of 1.5~2.5°C / min, and after uniform heating, it is heated to 750~800°C at a rate of 1~1.5°C / min. After uniform heating, it is kept at the temperature for 1~3 hours, and then cooled to obtain a stress-relieved blank.

[0011] S4. The stress-relief blank is cleaned and then subjected to nitriding treatment to obtain a surface-hardened zirconium sphere.

[0012] In one possible implementation,

[0013] The zirconium material mentioned in S1 is metallic zirconium or a zirconium alloy.

[0014] In one possible implementation,

[0015] In S3, the cooling method is to first cool it to below 100°C in the furnace after heat preservation, and then air cool it after it is taken out of the furnace.

[0016] In the above possible implementations, further,

[0017] In S3, a vacuum environment is maintained before air cooling after the furnace is discharged, with a vacuum level below 0.33 Pa.

[0018] In one possible implementation,

[0019] In step S4, before cleaning the stress-relief blank, the stress-relief blank is precision machined to achieve the target product size; the cleaning process consists of ultrasonic cleaning, anhydrous ethanol cleaning, and drying.

[0020] In one possible implementation,

[0021] In S4, the process for performing the nitriding treatment includes:

[0022] The stress-relief blank is fixed inside a sealed nitriding furnace, and nitriding gas is continuously introduced into the nitriding furnace.

[0023] When the vacuum inside the nitriding furnace is reduced to below 10Pa, turn on the power supply and ignite the glow discharge; then maintain the gas supply for nitriding at 0.5~0.7L / min, the working current at 40~60A, and the working voltage at 750~850W.

[0024] After the temperature of the stress-relief blank exceeds 400℃, reduce the gas supply for nitriding to 0.2~0.4 L / min, reduce the working current to 10~30A, and control the heating rate to 1.5℃ / min until the temperature of the stress-relief blank reaches 700~750℃, and then keep it at that temperature for 3~6 hours.

[0025] After the heat preservation is completed, a nitriding blank is obtained. The working power is cut off, the gas supply for nitriding is stopped, and the gas inside the nitriding furnace is continuously evacuated until the nitriding blank is cooled to below 100°C with the furnace. Then, it is taken out of the furnace and air-cooled.

[0026] In the above possible implementations, further,

[0027] The gas used for nitriding is ammonia, with an NH3 content of ≥99.8%.

[0028] According to a second aspect of the present application, a surface-hardened zirconium sphere is provided, which is obtained according to the steps of the above-described surface-hardened zirconium sphere preparation method;

[0029] The sphericality of the zirconium sphere is within 0.04 mm, the surface of the zirconium sphere has a nitriding layer with a depth ≥100 μm, and the surface hardness of the nitriding layer is 500 HV ~ 900 HV.

[0030] According to a third aspect of the embodiments of this application, an application of the above-mentioned zirconium ball is provided, specifically a ball valve including a valve body, a ball valve ball, a valve seat and a valve stem, wherein the ball valve ball is made of the above-mentioned surface-hardened zirconium ball.

[0031] In one possible implementation,

[0032] The surface roughness of the ball in the ball valve is no greater than 1.6 μm;

[0033] The ball valve body is specifically a straight-through ball valve body with a diameter of DN25~DN500 and a ball diameter of 40~700mm.

[0034] Compared with the prior art, the present invention has at least the following advantages:

[0035] (1) The preparation method provided by the present invention can form a nitrided hardened layer on the surface of the zirconium sphere. The hardened layer can effectively improve the corrosion resistance and wear resistance of the parts, and improve the functionality and service life of the zirconium sphere.

[0036] (2) The preparation method provided by the present invention can effectively control the deformation of zirconium spheres during the preparation of the hardened layer, stabilize the sphere roundness, and ensure sealing performance.

[0037] (3) The processing method of the present invention has a relatively simple process flow and good economic efficiency.

[0038] (4) The zirconium spheres obtained by the preparation method provided by the present invention have good hardness, wear resistance and corrosion resistance, so they are very suitable for the valve core spheres of ball valves, which can improve the valve's life, accuracy and stability. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a side sectional view of a ball valve ball provided in Embodiment 1 of this application;

[0041] Figure 2 This is a microstructure diagram of the nitrided layer of the zirconium sphere provided in Example 3 of this application;

[0042] Figure 3 This is a gradient hardness diagram of the nitrided layer section of the zirconium sphere provided in Embodiment 3 of this application. Detailed Implementation

[0043] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of this application and for 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. Therefore, they should not be construed as limitations on the present invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0045] In a first aspect, this embodiment discloses a method for preparing surface-hardened zirconium spheres, which includes the following steps:

[0046] S1. Heat the zirconium material at 700~750℃, hold it at the temperature for 1~3 hours after it is uniformly heated, and then remove it from the furnace and air cool it.

[0047] S2. Process the cooled zirconium material to obtain a spherical blank;

[0048] S3. The spherical blank is heated to 500°C at a rate of 1.5~2.5°C / min, and after uniform heating, it is heated to 750~800°C at a rate of 1~1.5°C / min. After uniform heating, it is kept at the temperature for 1~3 hours, and then cooled to obtain a stress-relieved blank.

[0049] S4. The stress-relief blank is cleaned and then subjected to nitriding treatment to obtain a surface-hardened zirconium sphere.

[0050] In a preferred technical solution

[0051] The zirconium material mentioned in S1 is metallic zirconium or a zirconium alloy.

[0052] In a preferred technical solution

[0053] In S3, the cooling method is to first cool it to below 100°C in the furnace after heat preservation, and then air cool it after it is taken out of the furnace.

[0054] In the above preferred technical solution, further,

[0055] In S3, a vacuum environment is maintained before air cooling after the furnace is discharged, with a vacuum level below 0.33 Pa.

[0056] In a preferred technical solution

[0057] In step S4, before cleaning the stress-relief blank, the stress-relief blank is precision machined to achieve the target product size; the cleaning process consists of ultrasonic cleaning, anhydrous ethanol cleaning, and drying.

[0058] In a preferred technical solution

[0059] In S4, the process for performing the nitriding treatment includes:

[0060] The stress-relief blank is fixed inside a sealed nitriding furnace, and nitriding gas is continuously introduced into the nitriding furnace.

[0061] When the vacuum inside the nitriding furnace is reduced to below 10Pa, turn on the power supply and ignite the glow discharge; then maintain the gas supply for nitriding at 0.5~0.7L / min, the working current at 40~60A, and the working voltage at 750~850W.

[0062] After the temperature of the stress-relief blank exceeds 400℃, reduce the gas supply for nitriding to 0.2~0.4 L / min, reduce the working current to 10~30A, and control the heating rate to 1.5℃ / min until the temperature of the stress-relief blank reaches 700~750℃, and then keep it at that temperature for 3~6 hours.

[0063] After the heat preservation is completed, a nitriding blank is obtained. The working power is cut off, the gas supply for nitriding is stopped, and the gas inside the nitriding furnace is continuously evacuated until the nitriding blank is cooled to below 100°C with the furnace. Then, it is taken out of the furnace and air-cooled.

[0064] In the above preferred technical solution, further,

[0065] The gas used for nitriding is ammonia, with an NH3 content of ≥99.8%.

[0066] Secondly, this embodiment provides a surface-hardened zirconium sphere, which is obtained according to the steps of the above-described surface-hardened zirconium sphere preparation method;

[0067] The sphericality of the zirconium sphere is within 0.04 mm, the surface of the zirconium sphere has a nitriding layer with a depth ≥100 μm, and the surface hardness of the nitriding layer is 500 HV ~ 900 HV.

[0068] Thirdly, this embodiment provides an application of the surface-hardened zirconium ball described above, specifically a ball valve, including a valve body, a ball valve ball, a valve seat, and a valve stem, wherein the ball valve ball is made of the surface-hardened zirconium ball described above.

[0069] In a preferred technical solution

[0070] The surface roughness of the ball in the ball valve is no greater than 1.6 μm;

[0071] The ball valve body is specifically a straight-through ball valve body with a diameter of DN25~DN500 and a ball diameter of 40~700mm.

[0072] The following provides several more specific implementation examples to further illustrate the technical effects of this application. Example 1

[0073] The zirconium ball valve body with a diameter of DN25 is made of R60702, a zirconium-containing alloy.

[0074] (1) First, the bar stock of R60702 was annealed at 700℃ for 1 hour and then air-cooled to obtain the annealed forging.

[0075] (2) After rough machining of the annealed forging, a spherical blank is obtained. The spherical blank is subjected to vacuum stress relief treatment with a vacuum degree of less than 0.33 Pa. The temperature is raised to 500°C at a rate of 1.5°C / min, and then raised to 750°C at a rate of 1°C / min. The temperature is held for 1 hour. After the holding is completed, the blank is cooled to below 100°C in the furnace and then air-cooled to obtain a stress-relieved blank.

[0076] (3) The stress-relief blanks are ultrasonically cleaned in sequence, cleaned with anhydrous ethanol, and then dried.

[0077] (4) The stress-relief blank after cleaning is subjected to ion nitriding treatment. The stress-relief blank is fixed in the nitriding furnace by tooling. The vacuum degree is evacuated to 8Pa and the power is turned on to ignite the glow discharge. During the heating stage, the gas supply is increased to 0.5L / min, the current is increased to 40A and the voltage is 750V. When the temperature of the stress-relief blank is greater than 400℃, the gas supply is reduced to 0.2L / min and the current is reduced to 20A. The heating rate is controlled to 1.5℃ / min to 700℃ and held for 3h. After nitriding, the glow discharge power is cut off, the valve is closed and the gas supply is stopped. The vacuum side pump continues to pump gas so that the workpiece is cooled to below 100℃ in the vacuum environment. After being removed from the furnace and air-cooled, the ball valve ball is obtained.

[0078] The obtained ball valve ball was tested, and the test results showed that its nitriding layer depth was 122μm, the surface hardness was 675HV0.2, which is about 3.8 times the hardness of R60702 substrate (178HV0.2), and the sphericality of the ball was 0.01mm. Example 2

[0079] The zirconium ball valve body with a diameter of DN150 is made of alloy R60705, which is a zirconium-containing alloy.

[0080] (1) First, the R60705 bar stock was annealed at 720℃ for 1.5h and then air-cooled to obtain the annealed forging.

[0081] (2) After annealing, the forging is rough machined to obtain a spherical blank. The spherical blank is subjected to vacuum stress relief treatment with a vacuum degree of less than 0.33 Pa. The temperature is raised to 500°C at a rate of 1.5°C / min, and then raised to 750°C at a rate of 1°C / min. The temperature is held for 1.5 hours. After the holding is completed, the temperature is cooled to below 100°C in the furnace and then air-cooled to obtain a stress-relieved blank.

[0082] (3) The stress-relief blanks are ultrasonically cleaned in sequence, cleaned with anhydrous ethanol, and then dried.

[0083] (4) The stress-relief blank after cleaning is subjected to ion nitriding treatment. The stress-relief blank is fixed in the nitriding furnace by tooling. The vacuum degree is evacuated to 7Pa and the power is turned on to ignite the glow discharge. During the heating stage, the gas supply is increased to 0.5L / min, the current is increased to 45A and the voltage is 780V. When the temperature of the stress-relief blank is greater than 400℃, the gas supply is reduced to 0.2L / min and the current is reduced to 20A. The heating rate is controlled to 1.5℃ / min to 720℃ and held for 4h. After nitriding, the glow discharge power is cut off, the valve is closed and the gas supply is stopped. The vacuum side pump continues to pump gas so that the workpiece is cooled to below 100℃ in the vacuum environment. After being removed from the furnace and air-cooled, the ball valve ball is obtained.

[0084] The obtained ball valve ball was tested, and the test results showed that its nitriding layer depth was 139μm, the surface hardness was 847HV0.2, which is about 4.3 times the hardness of R60705 substrate (197HV0.2), and the ball roundness was 0.02mm. Example 3

[0085] The alloy raw material used to prepare the DN300 zirconium ball valve body is grade R60702, which is a zirconium-containing alloy;

[0086] (1) The bar stock of R60702 was annealed at 750℃ for 2 hours and then air-cooled to obtain the annealed forging.

[0087] (2) After annealing, the forging is rough machined to obtain a spherical blank. The spherical blank is subjected to vacuum stress relief treatment with a vacuum degree of less than 0.33 Pa. The temperature is raised to 500°C at a rate of 2°C / min, and then raised to 780°C at a rate of 1.5°C / min. The temperature is held for 2 hours. After the holding is completed, the temperature is cooled to below 100°C in the furnace and then air-cooled to obtain a stress-relieved blank.

[0088] (3) The stress-relief blanks are subjected to ultrasonic cleaning in sequence, followed by cleaning with anhydrous ethanol and drying.

[0089] (4) The stress-relief blank after cleaning is subjected to ion nitriding treatment. The stress-relief blank is fixed in the nitriding furnace by tooling. The vacuum degree is evacuated to 5Pa and the power is turned on to ignite the glow discharge. During the heating stage, the gas supply is increased to 0.6L / min, the current is increased to 50A, and the voltage is 780V. When the temperature of the stress-relief blank is greater than 400℃, the gas supply is reduced to 0.3L / min and the current is reduced to 20A. The heating rate is controlled to 1.5℃ / min to 750℃ and held for 5h. After nitriding, the glow discharge power is cut off, the valve is closed and the gas supply and evacuation are stopped. The workpiece is cooled to below 100℃ in the nitriding atmosphere and then air-cooled after being taken out of the furnace to obtain the ball valve ball.

[0090] The obtained ball valve ball was tested, and the test results showed that its nitriding layer depth was 148μm, the surface hardness was 753HV0.2, which is about 4.2 times the hardness of R60702 substrate (178HV0.2), and the sphericality of the ball was 0.03mm. Example 4

[0091] The alloy raw material used to prepare the DN500 zirconium ball valve ball is grade R60702, which is a zirconium-containing alloy.

[0092] (1) First, the 60702 bar stock was annealed at 750℃ for 3 hours and then air-cooled to obtain the annealed forging.

[0093] (2) After annealing, the forging is rough machined to obtain a spherical blank. The spherical blank is subjected to vacuum stress relief treatment with a vacuum degree of less than 0.33 Pa. The temperature is raised to 500°C at a rate of 2.5°C / min, and then raised to 800°C at a rate of 1.5°C / min. The temperature is held for 3 hours. After the holding is completed, the temperature is cooled to below 100°C in the furnace and then air-cooled to obtain a stress-relieved blank.

[0094] (3) The stress-relief blanks are subjected to ultrasonic cleaning in sequence, followed by cleaning with anhydrous ethanol and drying.

[0095] (4) The stress-relief blank is subjected to ion nitriding treatment. The stress-relief blank is fixed in the nitriding furnace by tooling. The vacuum degree is evacuated to 5Pa and the power is turned on to ignite the glow discharge. During the heating stage, the gas supply is increased to 0.7 L / min, the current is increased to 60A and the voltage is 850V. When the temperature of the stress-relief blank is greater than 400℃, the gas supply is reduced to 0.4 L / min and the current is reduced to 30A. The heating rate is controlled to 1.5℃ / min to 750℃ and held for 6h. After nitriding, the glow discharge power is cut off and the valve is closed to stop the gas supply and evacuation. The workpiece is cooled to below 100℃ in the nitriding atmosphere and then air-cooled after being taken out of the furnace to obtain the ball valve ball.

[0096] The obtained ball valve ball was tested, and the test results showed that its nitriding layer depth was 159μm, the surface hardness was 773HV0.2, which is about 4.2 times the hardness of R60702 substrate (178HV0.2), and the ball roundness was 0.04mm.

[0097] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0098] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application 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 therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A method for preparing surface-hardened zirconium spheres, characterized in that, Includes the following steps: S1. Heat the zirconium material to 700~750℃, hold it at the same temperature for 1~3 hours, and then remove it from the furnace and air cool it. S2. Process the cooled zirconium material to obtain a spherical blank; S3. The spherical blank is heated to 500°C at a rate of 1.5~2.5°C / min, and after uniform heating, it is heated to 750~800°C at a rate of 1~1.5°C / min. After uniform heating, it is kept at the temperature for 1~3 hours, and then cooled to obtain a stress-relieved blank. In S3, the cooling method is to first cool the furnace to below 100°C after heat preservation, and then air cool after removal from the furnace; before air cooling after removal from the furnace, a vacuum environment is maintained with a vacuum degree below 0.33Pa; S4. The stress-relief blank is cleaned and then nitrided to obtain a surface-hardened zirconium sphere. In S4, the process for performing the nitriding treatment includes: The stress-relief blank is fixed inside a sealed nitriding furnace, and nitriding gas is continuously introduced into the nitriding furnace. When the nitriding furnace is evacuated to below 10Pa, turn on the power supply and ignite the glow discharge; then maintain the gas supply for nitriding at 0.5~0.7L / min, the working current at 40~60A, and the working voltage at 750~850W. After the temperature of the stress-relief blank exceeds 400℃, reduce the gas supply for nitriding to 0.2~0.4 L / min, reduce the working current to 10~30A, and control the heating rate to 1.5℃ / min until the temperature of the stress-relief blank reaches 700~750℃, and then keep it at that temperature for 3~6 hours. After the heat preservation is completed, a nitriding blank is obtained. The working power is cut off, the gas supply for nitriding is stopped, and the gas inside the nitriding furnace is continuously evacuated until the nitriding blank is cooled to below 100°C with the furnace. Then, it is taken out of the furnace and air-cooled.

2. The method for preparing surface-hardened zirconium spheres according to claim 1, characterized in that, The zirconium material mentioned in S1 is metallic zirconium or a zirconium alloy.

3. The method for preparing surface-hardened zirconium spheres according to claim 1, characterized in that, In step S4, before cleaning the stress-relief blank, the stress-relief blank is precision machined to achieve the target product size; the cleaning process consists of ultrasonic cleaning, anhydrous ethanol cleaning, and drying.

4. The method for preparing surface-hardened zirconium spheres according to claim 1, characterized in that, The gas used for nitriding is ammonia, with an NH3 content of ≥99.8%.

5. A surface-hardened zirconium sphere, characterized in that, It is obtained by the steps of the method for preparing surface-hardened zirconium spheres according to any one of claims 1 to 4; The sphericality of the zirconium sphere is within 0.04 mm, the surface of the zirconium sphere has a nitriding layer with a depth ≥100 μm, and the surface hardness of the nitriding layer is 500 HV ~ 900 HV.

6. A ball valve, comprising a valve body, a ball, a seat, and a stem, characterized in that, The ball valve body is made of the surface-hardened zirconium material ball as described in claim 5.

7. A ball valve according to claim 6, characterized in that, The surface roughness of the ball in the ball valve is no greater than 1.6 μm; The ball valve body is specifically a straight-through ball valve body with a diameter of DN25~DN500 and a ball diameter of 40~700mm.

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