Manufacturing method of composite cutting tool

Abstract

The invention relates to the technical field of cutter manufacturing, in particular to a manufacturing method of a composite cutter, which comprises the following steps: S1, preparing a hard alloy matrix by adopting a positive carbon sintering technology, so that the cobalt content of the hard alloy matrix is gradually reduced from inside to outside; s2, chemical cobalt removal treatment is conducted on the surface of the hard alloy matrix, and a cobalt-poor area is formed on the surface of the hard alloy matrix; s3, seed crystal planting is conducted on the hard alloy matrix; and S4, the hard alloy matrix is plated with a multi-layer composite structure diamond coating through a chemical deposition technology, a micron diamond coating, a gradient diamond coating and a nano diamond coating are formed from inside to outside, and preparation of the composite cutting tool is completed. The bonding strength of the hard alloy and the artificial diamond can be improved, and the service life of the cutter is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of tool manufacturing, and particularly relates to a manufacturing method for a composite tool. Background Art

[0002] Cemented carbide tools are known as the "teeth of industry" and are widely used in various fields of the national economy. Diamond-coated tools have excellent hardness, wear resistance and thermal conductivity, and are irreplaceable in the processing of difficult-to-cut materials such as graphite, high-silicon aluminum alloy, carbon fiber reinforced plastic, etc. in high-precision application fields such as military and aerospace.

[0003] The binder cobalt element in cemented carbide has a solid solubility for diamond, which will inhibit the nucleation of diamond during the deposition process and catalyze the growth of the intermediate graphite layer, resulting in the spontaneous separation of the diamond coating from the substrate. This is the main factor affecting the film-substrate bonding performance. Directly plating an artificial diamond coating on cemented carbide is likely to fall off, resulting in the failure of the composite tool combining cemented carbide and artificial diamond.

[0004] Therefore, a manufacturing method for a composite tool is needed to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a manufacturing method for a composite tool, which can improve the bonding strength between cemented carbide and artificial diamond and extend the service life of the tool.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] A manufacturing method for a composite tool includes the following steps:

[0008] S1. Prepare a cemented carbide substrate by using a positive carbon sintering technique, so that the cobalt content of the cemented carbide substrate gradually decreases from the inside to the outside;

[0009] S2. Perform chemical decobaltization treatment on the surface of the cemented carbide substrate to form a cobalt-depleted area on the surface of the cemented carbide substrate;

[0010] S3. Perform seed crystal implantation on the cemented carbide substrate;

[0011] S4. Use a chemical deposition technique to deposit a multi-layer composite structure diamond coating on the cemented carbide substrate, and form a micron diamond coating, a gradient diamond coating and a nano diamond coating from the inside to the outside to complete the preparation of the composite tool.

[0012] Further, preparing the cemented carbide substrate by using a positive carbon sintering technique includes the following steps:

[0013] S11. Take tungsten carbide with a total carbon content 0.1%-0.4% lower than the stoichiometric content as raw material, mix it with cobalt powder and ball mill to prepare a WC-Co hard alloy mixture, and press it into a button bit blank. The mass fraction of cobalt powder is 1%-12%.

[0014] S12. Pre-sinter the button bit blank in a nitrogen atmosphere for 0.5 h - 2 h, and the pre-sintering temperature is 700°C - 1000°C.

[0015] S13. Conduct final sintering at a sintering temperature of 1300°C - 1500°C to obtain a hard alloy button bit with uniformly distributed fine-grained η phase.

[0016] S14. Bury the sintered hard alloy button bit in a crucible filled with graphite powder and Al2O3 powder, place the crucible in a pusher furnace, and heat-treat it at 1450°C for 2 h in a carbon-containing atmosphere to obtain the hard alloy substrate.

[0017] Further, the carbon-containing atmosphere includes methane and carbon monoxide gases.

[0018] Further, in step S11, the mass fraction of cobalt powder is 6%.

[0019] Further, step S2 includes the following steps:

[0020] S21. Ultrasonically clean the hard alloy substrate.

[0021] S22. Immerse it in an acidic solution for 1 min - 6 min; immerse it in an alkaline solution for 2 min - 8 min, and finally immerse it in an acidic solution for 2 min - 10 min.

[0022] Further, step S3 includes the following steps:

[0023] S31. Place the hard alloy substrate in a suspension containing a mixture of nanocrystalline and microcrystalline diamond particles, ultrasonically treat it and dry it. The mass fraction of the diamond mixture particles is 0.01% - 0.05%; the ultrasonic treatment time is 5 min - 30 min.

[0024] Further, in step S4, the deposition parameters for coating the microcrystalline diamond are as follows: the percentage of the carbon-containing gas in the total gas mass flow rate in the furnace is 0.5% - 3%, the deposition temperature is 700°C - 1000°C, the deposition pressure is 10 3 -10 4 Pa, and the deposition time is 1 h - 3 h.

[0025] Further, in the step S4, the deposition parameters of the gradient diamond coating are as follows: the percentage of carbon-containing gas in the total gas mass flow rate in the furnace is 0.5%-10%, the deposition temperature is 500°C-1000°C, and the deposition pressure is 10 3 -10 4 Pa, the deposition time is 0.5 h-1 h, the gas flow rate, temperature, and deposition pressure change linearly with time, and the micron diamond coating transitions to the nano diamond coating.

[0026] Further, in the step S4, the deposition parameters of the nano diamond coating are as follows: the percentage of carbon-containing gas in the total gas mass flow rate in the furnace is 3%-10%, the deposition temperature is 500°C-800°C, and the deposition pressure is 10 3 -10 4 Pa, the deposition time is 3 h-12 h.

[0027] Further, the single-layer thickness of the micron diamond coating is 1 μm-5 μm; the single-layer thickness of the nano diamond coating is 3 μm-10 μm; the single-layer thickness of the gradient diamond coating is 1 μm-5 μm.

[0028] Advantages of the present invention:

[0029] A manufacturing method of a composite tool provided by the present invention uses a positive carbon sintering technique to prepare a cemented carbide substrate, so that the cobalt content of the cemented carbide substrate gradually decreases from the inside to the outside. Then, chemical decobalt treatment is performed on the surface of the cemented carbide substrate to form a cobalt-depleted area on the surface of the cemented carbide substrate. After seed crystal implantation on the cemented carbide substrate, a multi-layer composite structure diamond coating is plated, and a micron diamond coating, a gradient diamond coating, and a nano diamond coating are formed from the inside to the outside to complete the preparation of the composite tool. In this way, by using the positive carbon sintering technique and combining chemical decobalt treatment, the cobalt on the surface of the cemented carbide substrate is reduced, providing more nucleation sites for the growth of diamond, helping to enhance the riveting force between the diamond coating and the substrate, and improving the bonding strength between the cemented carbide and the synthetic diamond. By forming a micron diamond coating, a gradient diamond coating, and a nano diamond coating on the cemented carbide body, the micron diamond coating has good film-substrate bonding performance, and the nano diamond coating has excellent fracture toughness. The diamond composite coating not only obtains a relatively smooth surface but also further improves the bonding performance of the film. Depositing a gradient diamond coating between the micron diamond coating and the nano diamond coating makes the bonding between diamond grains closer, helps to relieve the residual stress between the film layers, effectively relieves the mechanical impact force and thermal stress during the tool processing, and prolongs the tool life. Description of the drawings

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments of the present invention. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to the content of the embodiments of the present invention and these drawings.

[0031] Figure 1 It is a flowchart of a manufacturing method of a composite tool of the present invention. Detailed implementation manners

[0032] Before explaining any embodiment of the present application in detail, it should be understood that the present application is not limited to the structural details and component arrangements described in the following description or shown in the above drawings.

[0033] In the present application, the terms "include", "comprise", "have" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the presence of another identical element in the process, method, article or device including that element.

[0034] In the present application, the terms "connect", "combine", "couple", "mount" can be direct connection, combination, coupling or mounting, or can be indirect connection, combination, coupling or mounting. Among them, by way of example, direct connection means that two parts or components are connected together without the need for an intermediate member, and indirect connection means that two parts or components are respectively connected to at least one intermediate member, and these two parts or components are connected through the intermediate member. In addition, "connection" and "coupling" are not limited to physical or mechanical connection or coupling, and can include electrical connection or coupling.

[0035] In this application, those of ordinary skill in the art will understand that relative terms used in connection with quantities or conditions (e.g., "about", "approximately", "substantially", etc.) are intended to include the recited value and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances resulting from manufacturing, assembly, use, etc. associated with a particular value. Such terms should also be considered to disclose ranges defined by the absolute values of two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values that do not employ relative terms should also be disclosed as specific values having tolerances. In addition, "substantially" when expressing relative angular positional relationships (e.g., substantially parallel, substantially perpendicular) may refer to plus or minus a certain number of degrees (e.g., 1 degree, 5 degrees, 10 degrees or more) from the indicated angle.

[0036] In this application, those of ordinary skill in the art will understand that the functions performed by components can be performed by one component, multiple components, one part, or multiple parts. Similarly, the functions performed by parts can also be performed by one part, one component, or a combination of multiple parts.

[0037] In this application, the orientation terms such as "upper", "lower", "left", "right", "front", "rear", etc. are described based on the orientation and positional relationship shown in the drawings, and should not be construed as limiting the embodiments of this application. In addition, in the context, it should also be understood that when it is mentioned that one element is connected "above" or "below" another element, it can not only be directly connected "above" or "below" another element, but also be indirectly connected "above" or "below" another element through an intermediate element. It should also be understood that the orientation terms such as the upper side, the lower side, the left side, the right side, the front side, the rear side, etc. not only represent the positive orientation, but can also be understood as the side orientation. For example, the lower side can include directly below, lower left, lower right, lower front, and lower rear, etc.

[0038] In the process of manufacturing a composite tool, in order to improve the bonding strength between cemented carbide and synthetic diamond and extend the service life of the tool, as Figure 1 shown, the present invention provides a method for manufacturing a composite tool. The method for manufacturing a composite tool includes the following steps:

[0039] S1. Prepare a cemented carbide substrate using a positive carbon sintering technique, such that the cobalt content of the cemented carbide substrate gradually decreases from the inside to the outside;

[0040] S2. Perform a chemical decobalt treatment on the surface of the cemented carbide substrate to form a cobalt-depleted zone on the surface of the cemented carbide substrate;

[0041] S3. Perform seed crystal implantation on the cemented carbide substrate;

[0042] S4. Use chemical deposition technology to deposit a multi-layer composite structure diamond coating on the cemented carbide substrate, forming a micron diamond coating, a gradient diamond coating, and a nano diamond coating from the inside out to complete the preparation of the composite tool.

[0043] Through the above method, using positive carbon sintering technology combined with chemical decobalt treatment reduces the cobalt on the surface of the cemented carbide substrate, providing more nucleation sites for the growth of diamond, helping to enhance the riveting force between the diamond coating and the substrate, and improving the bonding strength between the cemented carbide and synthetic diamond. By forming a micron diamond coating, a gradient diamond coating, and a nano diamond coating on the cemented carbide body, the micron diamond coating has good film-substrate bonding performance, and the nano diamond coating has excellent fracture toughness. The diamond composite coating not only obtains a relatively smooth surface but also further improves the bonding performance of the film. Depositing a gradient diamond coating between the micron diamond coating and the nano diamond coating makes the bonding between diamond grains closer, helps to relieve the residual stress between the film layers, effectively reduces the mechanical impact force and thermal stress during the tool processing, and prolongs the tool life.

[0044] Furthermore, the preparation of the cemented carbide substrate by positive carbon sintering technology includes the following steps:

[0045] S11. Take tungsten carbide with a total carbon content 0.1%-0.4% lower than the stoichiometric content as the raw material, mix it with cobalt powder, and prepare a WC-Co cemented carbide mixture by ball milling and press it into a button blank. The mass fraction of cobalt powder is 1%-12%.

[0046] S12. Pre-sinter the button blank in a nitrogen atmosphere for 0.5h - 2h, and the pre-sintering temperature is 700°C - 1000°C.

[0047] S13. Conduct the final sintering, and the sintering temperature is 1300°C - 1500°C to obtain a cemented carbide button with uniformly distributed fine-grained η phase.

[0048] S14. Bury the sintered cemented carbide button in a crucible filled with graphite powder and Al2O3 powder, put the crucible into a pusher furnace, and heat-treat it at 1450°C for 2h in a carbon-containing atmosphere to obtain the cemented carbide substrate. Through the above method, the surface layer of the WC-Co gradient structure cemented carbide substrate prepared by positive carbon sintering technology is a cobalt-depleted normal structure (WC + γ), which inhibits the reduction of the mechanical properties of the cemented carbide due to the migration and diffusion of elements during the CVD diamond coating deposition process and improves the film-substrate bonding force between the cemented carbide substrate and the CVD diamond coating; the core is a cobalt-rich abnormal structure (WC + γ + η) containing uniformly distributed fine η phase, which helps to improve the material toughness.

[0049] Further, the carbon-containing atmosphere includes methane and carbon monoxide gases. Carburizing heat treatment is achieved by heat-treating the cemented carbide button teeth in the carbon-containing atmosphere at 1450 °C.

[0050] Further, in step S11, the mass fraction of cobalt powder is 6%. When the mass fraction of cobalt powder is 6%, it is the optimal mass fraction of cobalt powder for the preparation of cemented carbide.

[0051] Further, step S2 includes the following steps:

[0052] S21. Ultrasonically clean the cemented carbide substrate;

[0053] S22. Immerse it in an acidic solution for 1 min - 6 min; immerse it in an alkaline solution for 2 min - 8 min, and finally immerse it in an acidic solution for 2 min - 10 min. Specifically, the volume ratio of the acid solution is V HNO3 :V HCl :V H2O =(1 - 5):(5 - 20):100, immerse it in the alkaline solution for 2 - 8 min, and the mass ratio of the alkaline solution is w K3[Fe(CN)6] :w NaOH :w H2O =1:(3 - 5):10, and finally obtain a cobalt-depleted zone with a uniform surface layer, with a thickness of 2 - 3 μm.

[0054] Further, step S3 includes the following steps:

[0055] S31. Place the cemented carbide substrate in a suspension containing a mixture of nanocrystalline and microcrystalline diamond particles, ultrasonically treat it and dry it; the mass fraction of the diamond mixture particles is 0.01% - 0.05%; the ultrasonically treating time is 5 min - 30 min.

[0056] Further, in step S4, the deposition parameters for depositing the microcrystalline diamond coating are: the percentage of the carbon-containing gas in the total gas mass flow rate in the furnace is 0.5% - 3%, the deposition temperature is 700 °C - 1000 °C, the deposition pressure is 10 3 -10 4 Pa, and the deposition time is 1 h - 3 h. The microcrystalline diamond has good film-substrate bonding performance and can further improve the bonding performance of the film.

[0057] Further, in step S4, the deposition parameters for depositing the gradient diamond coating are: the percentage of the carbon-containing gas in the total gas mass flow rate in the furnace is 0.5% - 10%, the deposition temperature is 500 °C - 1000 °C, the deposition pressure is 10 3 -10 4At a deposition time of 0.5 h - 1 h, the gas flow rate, temperature, and deposition pressure change linearly with time, transitioning from a micron diamond coating to a nano diamond coating. By depositing a gradient diamond coating, the bonding between diamond grains becomes tighter, which helps to alleviate the residual stress between the film layers, effectively reducing the mechanical impact force and thermal stress during the tool machining process and extending the tool life.

[0058] Further, in step S4, the deposition parameters for the nano diamond coating are as follows: the percentage of the carbon-containing gas in the total gas mass flow rate in the furnace is 3% - 10%, the deposition temperature is 500 °C - 800 °C, and the deposition pressure is 10 3 -10 4 Pa, and the deposition time is 3 h - 12 h. Nano diamond has excellent fracture toughness, which can reduce the surface roughness of the composite tool and obtain a relatively smooth surface.

[0059] Further, the single-layer thickness of the micron diamond coating is 1 μm - 5 μm; the single-layer thickness of the nano diamond coating is 3 μm - 10 μm; the single-layer thickness of the gradient diamond coating is 1 μm - 5 μm. The composite tool manufactured in the above manner can be applied to the laminated machining of various composite materials such as carbon fiber, glass fiber, high-silicon aluminum alloy, titanium alloy, and graphite.

[0060] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A manufacturing method of a composite tool, characterized in that, It includes the following steps: S1. Prepare a cemented carbide substrate by using a positive carbon sintering technique, such that the cobalt content of the cemented carbide substrate gradually decreases from the inside to the outside; S2. Conduct a chemical decobalt treatment on the surface of the cemented carbide substrate to form a cobalt-depleted zone on the surface of the cemented carbide substrate; S3. Conduct seed crystal implantation on the cemented carbide substrate; S4. Use a chemical deposition technique to deposit a multi-layer composite structure diamond coating on the cemented carbide substrate, and form a micron diamond coating, a gradient diamond coating, and a nano diamond coating from the inside to the outside, thus completing the preparation of the composite tool.

2. The manufacturing method of the composite tool according to claim 1, characterized in that, The preparation of the cemented carbide substrate by using a positive carbon sintering technique includes the following steps: S11. Take tungsten carbide with a total carbon content 0.1%-0.4% lower than the stoichiometric content as raw material, mix it with cobalt powder and ball mill to prepare a WC-Co cemented carbide mixture, and press it into a button blank. The mass fraction of cobalt powder is 1%-12%; S12. Pre-sinter the button blank in a nitrogen atmosphere for 0.5h-2h, and the pre-sintering temperature is 700°C-1000°C; S13. Conduct final sintering, and the sintering temperature is 1300°C-1500°C to obtain a cemented carbide button with uniformly distributed fine-grained η phase; S14. Bury the sintered cemented carbide button in a crucible filled with graphite powder and Al2O3 powder, place the crucible in a pusher furnace, and conduct heat treatment at 1450°C for 2h in a carbon-containing atmosphere to obtain the cemented carbide substrate.

3. The manufacturing method of the composite tool according to claim 2, characterized in that, The carbon-containing atmosphere contains methane and carbon monoxide gases.

4. The manufacturing method of the composite tool according to claim 2, characterized in that, In the step S11, the mass fraction of cobalt powder is 6%.

5. The manufacturing method of the composite tool according to claim 1, characterized in that, The step S2 includes the following steps: S21. Ultrasonically clean the cemented carbide substrate; S22. Immerse it in an acidic solution for 1min-6min; immerse it in an alkaline solution for 2min-8min, and finally immerse it in an acidic solution for 2min-10min.

6. The manufacturing method of the composite tool according to claim 1, characterized in that, The step S3 includes the following steps: S31. Place the cemented carbide substrate in a suspension containing a mixture of nanocrystalline and microcrystalline diamond particles, conduct ultrasonic treatment and dry it. The mass fraction of the diamond mixture particles is 0.01%-0.05%; the ultrasonic treatment time is 5min-30min.

7. The manufacturing method of the composite tool according to claim 1, characterized in that In the step S4, the deposition parameters for the micron diamond coating are as follows: the percentage of the carbon-containing gas in the total gas mass flow rate in the furnace is 0.5%-3%, the deposition temperature is 700°C-1000°C, the deposition pressure is 10 3 -10 4 Pa, and the deposition time is 1h-3h.

8. The manufacturing method of the composite tool according to claim 1, characterized in that, In the step S4, the deposition parameters for the gradient diamond coating are as follows: the percentage of carbon-containing gas in the total gas mass flow rate in the furnace is 0.5%-10%, the deposition temperature is 500°C-1000°C, and the deposition pressure is 10 3 -10 4 Pa, the deposition time is 0.5 h-1 h, and the gas flow rate, temperature, and deposition pressure change linearly with time, transitioning from the micron diamond coating to the nano diamond coating.

9. The manufacturing method of the composite tool according to claim 8, characterized in that, In the step S4, the deposition parameters for the nano-diamond coating are as follows: the percentage of the carbon-containing gas in the total gas mass flow rate in the furnace is 3% - 10%, the deposition temperature is 500°C - 800°C, the deposition pressure is 10 3 - 10 4 Pa, and the deposition time is 3 h - 12 h.

10. The manufacturing method of the composite tool according to claim 1, characterized in that The single-layer thickness of the micron diamond coating is 1μm-5μm; the single-layer thickness of the nano diamond coating is 3μm-10μm; the single-layer thickness of the gradient diamond coating is 1μm-5μm.

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