Preparation method of cemented carbide bionic coating tool material for high-speed railway turnout processing

Abstract

The present invention discloses a method for preparing a cemented carbide biomimetic coating tool material for high-speed railway turnout machining, the method comprising: selecting a WC-12Co coarse-grained cemented carbide tool blank as a substrate, performing a surface ion source-assisted magnetron sputtering treatment after surface cleaning to obtain a biomimetic coating on the substrate; and subjecting the prefabricated cemented carbide tool with the biomimetic coating to a diffusion heat treatment to obtain a final coated tool material. The cemented carbide coating obtained by the present invention has a biomimetic "brick-mud" layered structure, a coating / substrate interface bonding strength of ≥22MPa, a coating thickness of 3.1 to 3.7 microns, a coating surface room temperature hardness of ≥26GPa, and a coating surface hardness of ≥17GPa at 1000°C.

Description

Technical Field

[0001] The invention belongs to the technical field of cemented carbide coating tool preparation, and in particular relates to a method for preparing a cemented carbide bionic coating tool material for high-speed railway turnout processing. Background Art

[0002] The cemented carbide coated tool material is based on cemented carbide and is coated with a wear-resistant thin layer through physical or chemical vapor deposition technology. The coating material is mainly refractory metal compounds, such as titanium carbide, tantalum carbide and zirconium carbide, which have excellent high-temperature resistance and wear resistance, and can improve the processing accuracy and life of cemented carbide tools. However, due to the large differences in the composition and structure of the coating material and the cemented carbide substrate, the coating / substrate interface bonding is weak, the coating is easy to fall off, and it is difficult for the coating to fully exert its effectiveness. Therefore, finding a new method to solve the problem of weak cemented carbide coating / substrate interface bonding is crucial to improving its performance.

[0003] By using bionic structure coating design and interface diffusion heat treatment to improve the coating / substrate interface bonding performance and coating toughness, and give full play to the coating's high temperature resistance and wear resistance advantages, it is a key means to extend the life of cemented carbide coating tools and improve their processing accuracy. Summary of the Invention

[0004] In view of this, the main purpose of the present invention is to provide a method for preparing a cemented carbide bionic coating tool material for high-speed railway turnout processing.

[0005] In order to achieve the above objectives, the present invention is implemented by adopting the following technical solutions:

[0006] An embodiment of the present invention provides a method for preparing a cemented carbide bionic coating tool material for high-speed railway turnout machining, the method comprising:

[0007] WC-12Co coarse-grained carbide tool blank was selected as the substrate, and after surface cleaning, it was subjected to surface ion source assisted magnetron sputtering treatment to obtain a bionic coating on the substrate.

[0008] The cemented carbide tool with prefabricated bionic coating is subjected to diffusion heat treatment to obtain the final coating tool material.

[0009] In the above solution, the WC-12Co coarse-grained cemented carbide tool blank is selected as the matrix, specifically: the average size of tungsten carbide grains in the WC-12Co coarse-grained cemented carbide tool blank is 13 to 24 microns, and the bending strength is 3400 to 3780 MPa.

[0010] In the above scheme, the surface cleaning treatment is followed by surface ion source assisted magnetron sputtering treatment, specifically: the surface cleaning treatment uses an ultrasonic cleaner, the medium is anhydrous ethanol, and the ultrasonic frequency is 45 to 60 Hz; pure metal target materials and high-purity graphite target materials are used, and a composite sputtering treatment is performed by regulating the anode radio frequency ion beam to prepare a bionic "brick-mud" layered structure composed of WC-Co and diamond-like carbon film.

[0011] In the above solution, the pure metal target materials are W and Co, with a purity of ≥99.5%, and the purity of the high-purity graphite target material is ≥99.9%.

[0012] In the above scheme, the composite sputtering treatment is specifically as follows: the anode RF ion beam current is 1500~1650mA, the cathode target electric power is 310~350W for W, 130~150W for Co and 160~180W for graphite, the electric power for W and Co gradually decreases at a rate of 0.3~0.5W per minute, and the electric power for graphite gradually increases at a rate of 0.7~0.9W per minute; a mixed gas of methane and argon is used, the volume ratio of methane:argon is 1:6~11, and the continuous sputtering time is 26 minutes to 53 minutes.

[0013] In the above scheme, the diffusion heat treatment is carried out in a vacuum furnace with a vacuum degree of ≤5×10 -4 , temperature 220℃~310℃, keep warm for 6~9 minutes, and the heating / cooling rate is 3~5℃ / min.

[0014] In the above scheme, the cemented carbide coating has a bionic "brick-mud" layered structure, the coating / substrate interface bonding strength is ≥22MPa, the coating thickness is 3.1-3.7 microns, the coating surface room temperature hardness is ≥26GPa, and the coating surface hardness at 1000℃ is ≥17GPa.

[0015] Compared with the existing technology, the cemented carbide coating prepared by the present invention has a bionic "brick-mud" layered structure, the coating / substrate interface bonding strength is ≥22MPa, the coating thickness is 3.1-3.7 microns, the coating surface room temperature hardness is ≥26GPa, and the coating surface hardness at 1000℃ is ≥17GPa. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, article, or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, article, or device comprising the element.

[0018] An embodiment of the present invention provides a method for preparing a cemented carbide bionic coating tool material for high-speed railway turnout machining, comprising the following steps:

[0019] S101: selecting a WC-12Co coarse-grained carbide tool blank as a substrate, performing surface ion source assisted magnetron sputtering treatment after surface cleaning treatment, and obtaining a bionic coating on the substrate;

[0020] Specifically, a WC-12Co coarse-grained carbide tool blank with an average tungsten carbide grain size of 13 to 24 microns and a bending strength of 3400 to 3780 MPa was selected as the substrate. The surface was cleaned using an ultrasonic cleaner in an anhydrous ethanol medium at an ultrasonic frequency of 45 to 60 Hz. Then, pure W and Co metals with a purity of ≥99.5% and high-purity graphite with a purity of ≥99.9% were used as targets for surface ion source-assisted magnetron sputtering. The anode RF ion beam current was set to 1500 to 1650 mA, and the cathode target power was set to W( The electric power of the W and Co cathode targets was gradually reduced at a rate of 0.3 to 0.5 watts per minute, and the electric power of the graphite cathode target was gradually increased at a rate of 0.7 to 0.9 watts per minute; a methane + argon mixed gas with a methane:argon volume ratio of 1:6 to 11 and a continuous sputtering time of 26 to 53 minutes was used to prepare a bionic "brick-mud" layered structure bionic coating composed of WC-Co and diamond-like carbon film on a WC-12Co coarse-grained cemented carbide substrate.

[0021] S102: Performing diffusion heat treatment on the cemented carbide tool with the prefabricated bionic coating to obtain a final coated tool material.

[0022] Specifically, the carbide coated tool is placed in a vacuum furnace for diffusion heat treatment with a vacuum degree of ≤5×10 -4 , temperature 220℃~310℃, keep warm for 6~9 minutes, heating / cooling rate is 3~5℃ / min, and obtain the final coating tool material.

[0023] The present invention first selects a WC-12Co coarse-grained cemented carbide tool blank as a substrate, performs surface ion source assisted magnetron sputtering treatment after surface cleaning treatment, selects pure metal and high-purity graphite target materials for the ion source assisted magnetron sputtering treatment, and prepares a bionic "brick-mud" layered structure composed of WC-Co and diamond-like film by regulating process parameters such as anode radio frequency ion beam, protective atmosphere and continuous sputtering time, obtains a bionic coating on the cemented carbide tool substrate, and finally performs diffusion heat treatment on the cemented carbide tool with prefabricated bionic coating; wherein the selection of pure metal and high-purity graphite target materials is, on the one hand, conducive to the precise regulation of coating components and element distribution through ion source assisted magnetron sputtering technology, and on the other hand, facilitates the formation of a bionic "brick-mud" layered structure composed of WC-Co and diamond-like film; the diffusion heat treatment is used to improve the metallurgical bonding at the interface of the substrate coating on the one hand, and to remove the internal stress of the bionic "brick-mud" layered structure on the other hand, thereby further improving the interface bonding performance and coating toughness.

[0024] The hard alloy coating prepared by the present invention has a bionic "brick-mud" layered structure, a coating / substrate interface bonding strength ≥22MPa, a coating thickness of 3.1-3.7 microns, a coating surface room temperature hardness ≥26GPa, and a coating surface hardness at 1000°C ≥17GPa.

[0025] Furthermore, in the process of preparing cemented carbide-coated tool materials, the present invention addresses the problem of weak cemented carbide coating / substrate interface bonding by employing a biomimetic structural coating design and interface diffusion heat treatment. The research examines the relationship between the cemented carbide substrate structure and properties, ion-source-assisted magnetron sputtering treatment, diffusion heat treatment process, and the hardness, interface bonding strength, and high-temperature mechanical properties of the cemented carbide-coated tool materials. Specifically, the present invention identifies the optimal cemented carbide substrate structure and properties, ion-source-assisted magnetron sputtering treatment, and diffusion heat treatment process for cemented carbide-coated tool materials, which maintain high hardness, interface bonding strength, and high-temperature mechanical properties. This method offers high composition control precision, strong process stability and repeatability, and can achieve a long life for the cemented carbide-coated tool materials.

[0026] The properties of the gold cemented carbide coated tool materials prepared in the following examples are shown in Table 1.

[0027] Example 1

[0028] A WC-12Co coarse-grained carbide tool blank with an average tungsten carbide grain size of 13 μm and a flexural strength of 3400 MPa was selected as the substrate. The surface was cleaned using an ultrasonic cleaner in anhydrous ethanol medium at an ultrasonic frequency of 45 Hz. Then, pure W and Co metals with a purity of ≥99.5% and high-purity graphite with a purity of ≥99.9% were used as targets for surface ion source-assisted magnetron sputtering. The anode RF ion beam current was set to 1500 mA, and the cathode target power was set to 200 Hz. W (310 W), Co (130 W) and graphite (160 W). The electric power of the W and Co cathode targets was gradually reduced at a rate of 0.3 to 0.5 W per minute, and the electric power of the graphite cathode target was gradually increased at a rate of 0.7 W per minute. A methane + argon mixed gas with a methane:argon volume ratio of 1:6 was used for a continuous sputtering time of 26 minutes to prepare a bionic "brick-mud" layered structure bionic coating composed of WC-Co and diamond-like carbon film on a WC-12Co coarse-grained cemented carbide substrate.

[0029] Finally, the carbide coated tool was placed in a vacuum furnace for diffusion heat treatment with a vacuum degree of 4×10 -4 , temperature 220℃, holding temperature for 6 minutes, heating / cooling rate of 3℃ / min, and the final coating tool material was obtained.

[0030] Example 2

[0031] A WC-12Co coarse-grained carbide tool blank with an average tungsten carbide grain size of 24 μm and a flexural strength of 3780 MPa was selected as the substrate. The surface was cleaned using an ultrasonic cleaner in anhydrous ethanol medium at an ultrasonic frequency of 60 Hz. Then, pure W and Co metals with a purity of ≥99.5% and high-purity graphite with a purity of ≥99.9% were used as targets for surface ion source-assisted magnetron sputtering. The anode RF ion beam current was set to 1650 mA, and the cathode target power was set to 200 Hz. The electric power of the W and Co cathode targets was gradually reduced at a rate of 0.5 watts per minute, and the electric power of the graphite cathode target was gradually increased at a rate of 0.9 watts per minute. A methane + argon mixed gas with a methane:argon volume ratio of 1:11 and a continuous sputtering time of 53 minutes was used to prepare a bionic "brick-mud" layered structure bionic coating composed of WC-Co and diamond-like carbon film on a WC-12Co coarse-grained cemented carbide substrate.

[0032] Finally, the carbide coated tool was placed in a vacuum furnace for diffusion heat treatment with a vacuum degree of 4×10 -4 , temperature 310℃, holding time 9 minutes, heating / cooling rate 5℃ / min, to obtain the final coating tool material.

[0033] Example 3

[0034] A WC-12Co coarse-grained carbide tool blank with an average tungsten carbide grain size of 18 μm and a bending strength of 3650 MPa was selected as the substrate. The surface was cleaned using an ultrasonic cleaner in anhydrous ethanol medium at an ultrasonic frequency of 50 Hz. Then, pure W and Co metals with a purity of ≥99.5% and high-purity graphite with a purity of ≥99.9% were used as targets for surface ion source-assisted magnetron sputtering. The anode RF ion beam current was set to 1600 mA, and the cathode target power was set to 200 Hz. W (330 W), Co (140 W) and graphite (170 W). The electric power of the W and Co cathode targets was gradually reduced at a rate of 0.3 to 0.5 W per minute, and the electric power of the graphite cathode target was gradually increased at a rate of 0.8 W per minute. A methane + argon mixed gas with a methane:argon volume ratio of 1:8 was used. The sputtering time was continuous for 43 minutes to prepare a bionic "brick-mud" layered structure bionic coating composed of WC-Co and diamond-like carbon film on a WC-12Co coarse-grained cemented carbide substrate.

[0035] Finally, the carbide coated tool was placed in a vacuum furnace for diffusion heat treatment with a vacuum degree of 5×10 -4 , temperature 260℃, holding temperature for 8 minutes, heating / cooling rate of 4℃ / min, and the final coating tool material was obtained.

[0036] Example 4

[0037] A WC-12Co coarse-grained carbide tool blank with an average tungsten carbide grain size of 21 μm and a bending strength of 3620 MPa was selected as the substrate. The surface was cleaned using an ultrasonic cleaner in anhydrous ethanol medium at an ultrasonic frequency of 55 Hz. Then, pure W and Co metals with a purity of ≥99.5% and high-purity graphite with a purity of ≥99.9% were used as targets for surface ion source-assisted magnetron sputtering. The anode RF ion beam current was set to 1650 mA, and the cathode target power was set to 200 Hz. W (340 W), Co (150 W) and graphite (160 W), the electric power of the W and Co cathode targets was gradually reduced at a rate of 0.3 to 0.5 W per minute, and the electric power of the graphite cathode target was gradually increased at a rate of 0.7 W per minute; a methane + argon mixed gas with a methane:argon volume ratio of 1:7 and a continuous sputtering time of 33 minutes was used to prepare a bionic "brick-mud" layered structure bionic coating composed of WC-Co and diamond-like carbon film on a WC-12Co coarse-grained cemented carbide substrate;

[0038] Finally, the carbide coated tool was placed in a vacuum furnace for diffusion heat treatment with a vacuum degree of 5×10 -4 , temperature 290℃, holding temperature for 8 minutes, heating / cooling rate of 5℃ / min, and the final coating tool material was obtained.

[0039] The performance parameters of the cemented carbide coating tool materials prepared in Examples 1 to 4 are shown in Table 1:

[0040] Table 1

[0041]

[0042] It can be concluded from the above table that the cemented carbide coating prepared by the present invention has a bionic "brick-mud" layered structure, the coating / substrate interface bonding strength is ≥22 MPa, the coating thickness is 3.1 to 3.7 microns, the coating surface room temperature hardness is ≥26 GPa, and the coating surface hardness at 1000°C is ≥17 GPa.

[0043] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a cemented carbide bionic coating tool material for high-speed railway turnout processing, characterized in that: The method comprises: WC-12Co coarse-grained carbide tool blank was selected as the substrate, and after surface cleaning, it was subjected to surface ion source assisted magnetron sputtering treatment to obtain a bionic coating on the substrate. Among them, after surface cleaning, pure metal targets and high-purity graphite targets were used, and composite sputtering treatment was performed by regulating the anode radio frequency ion beam to prepare a bionic "brick-mud" layered structure composed of WC-Co and diamond-like carbon film; The composite sputtering process is specifically as follows: the anode RF ion beam current is 1500-1650 mA, the cathode target power is 310-350 watts for W, 130-150 watts for Co, and 160-180 watts for graphite, respectively. The power for W and Co is gradually reduced at a rate of 0.3-0.5 watts per minute, and the power for graphite is gradually increased at a rate of 0.7-0.9 watts per minute. A methane and argon mixed gas is used, with a volume ratio of methane to argon of 1:6-11, and the sputtering time is 26 minutes to 53 minutes. The cemented carbide tool with prefabricated bionic coating is subjected to diffusion heat treatment to obtain the final coating tool material.

2. The method for preparing a cemented carbide bionic coating tool material for high-speed railway turnout processing according to claim 1, characterized in that: The WC-12Co coarse-grained cemented carbide tool blank is selected as the matrix, specifically: the average size of tungsten carbide grains in the WC-12Co coarse-grained cemented carbide tool blank is 13-24 microns, and the bending strength is 3400-3780 MPa.

3. The method for preparing a cemented carbide bionic coating tool material for high-speed railway turnout machining according to claim 1 or 2, characterized in that: After the surface cleaning treatment, the surface is subjected to a surface ion source assisted magnetron sputtering treatment, specifically: the surface cleaning treatment adopts an ultrasonic cleaner, the medium is anhydrous ethanol, and the ultrasonic frequency is 45-60 Hz.

4. The method for preparing a cemented carbide bionic coating tool material for high-speed railway turnout machining according to claim 3, characterized in that: The pure metal target materials are W and Co, with a purity of ≥99.5%, and the purity of the high-purity graphite target material is ≥99.9%.

5. The method for preparing a cemented carbide bionic coating tool material for high-speed railway turnout processing according to claim 4, characterized in that: The diffusion heat treatment is carried out in a vacuum furnace with a vacuum degree of ≤5×10 -4 , temperature 220℃~310℃, keep warm for 6~9 minutes, and the heating / cooling rate is 3~5℃ / min.

6. The method for preparing a cemented carbide bionic coating tool material for high-speed railway turnout machining according to claim 5, characterized in that: The cemented carbide coating has a bionic "brick-mud" layered structure, a coating / substrate interface bonding strength ≥22 MPa, a coating thickness of 3.1-3.7 microns, a coating surface room temperature hardness ≥26 GPa, and a coating surface hardness at 1000°C ≥17 GPa.

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