A cutting tool with submicron diamond coating and its preparation method and application

Abstract

The present application relates to the technical field of diamond tools, and specifically discloses a tool with a submicron diamond coating, its preparation method, and application. The method for preparing a tool with a submicron diamond coating disclosed in the present application comprises the following steps: preparing a tool substrate, soft abrasive sandblasting, surface roughening, Co removal treatment, and coating deposition; the soft abrasive sandblasting treatment is as follows: soft rubber with a particle size of 0.5-1.5 μm and diamond micropowder with a particle size of 0.1-0.5 μm are uniformly mixed at the softening temperature of the soft rubber in a weight ratio of 100:(1-5) to obtain sand material, and the surface of the tool substrate is sandblasted and polished using a directional jet of air as a medium. The tool with a submicron diamond coating obtained in the present application has high wear resistance and low roughness; in graphite processing, it can reduce the number of tool changes and machine tool downtime, reduce tool use costs, and improve processing efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of diamond cutting tools, and in particular to a cutting tool with a submicron diamond coating, a preparation method thereof, and an application thereof. Background Art

[0002] Graphite, with its physical and chemical properties such as high hardness, excellent conductivity, high-temperature resistance, and stable chemical properties, is widely used in industries such as molds, chemicals, metallurgy, nuclear industry, aerospace, and semiconductors. However, from a processing perspective, graphite is a typical non-metallic, brittle and fragile material with poor mechanical strength. It easily breaks during processing, generating fine dust and chips that easily adhere to the front and rear cutting edges of the tool and the machined surface, causing severe friction and impact on the cutting edge, leading to premature tool breakage, rapid wear, and even chipping and failure. This results in poor surface quality and dimensional accuracy of the workpiece, significantly increasing processing costs and time.

[0003] Currently, diamond-coated tools are commonly used for graphite machining. Diamond coatings deposit a diamond film with a specific structure on the tool surface to extend tool life. Diamonds are categorized into micron and nanocrystals based on their structure and size. Micron crystals are tetrahedral, columnar crystals with larger particles (>3μm). They significantly improve wear resistance, but have poor finish and are primarily used for rough machining. Nanocrystals are spherical or cauliflower-shaped crystals with small particles (1-100nm) that grow in stacks. They offer excellent finish and high precision, but suffer from poor wear resistance and are primarily used for finishing.

[0004] For example, in the machining of graphite electrodes, microcrystalline coated tools are typically first used to increase material removal rates. Small-particle nanocrystalline coatings are then used for pre-finishing and post-finishing. During the post-finishing process, the electrode's final, precise geometry is milled from the graphite blank. This overall process is complex, requiring frequent tool changes and resulting in high time costs. Summary of the Invention

[0005] In order to solve the above technical problems, the present application provides a cutting tool with a submicron diamond coating, a preparation method thereof, and an application thereof.

[0006] In a first aspect, the present application provides a method for preparing a tool with a submicron diamond coating, which specifically comprises the following steps: preparing a tool substrate, soft abrasive sandblasting, surface roughening, Co removal treatment, and coating deposition;

[0007] The method specifically includes the following steps: preparing a tool base, soft abrasive sandblasting treatment, surface roughening, Co removal treatment, and coating deposition; the soft abrasive sandblasting treatment is as follows: soft rubber with a particle size of 0.5-1.5 μm and diamond micropowder with a particle size of 0.1-0.5 μm are uniformly mixed at a weight ratio of 100:(1-5) under the condition of the softening temperature of the soft rubber to obtain sand material, and the surface of the tool base is sandblasted and ground using a directional jet of air as a medium.

[0008] This application utilizes soft rubber and diamond micropowder in the above-mentioned weight ratio as soft abrasives, and controls the particle size of the two, then sandblasts the tool base, uses a directional jet of airflow as a medium, impacts the surface of the tool, and performs micro-passivation on the tool edge, which can remove the surface micro-serrations that are inevitably generated on the tool edge during the grinding process.

[0009] During the preparation process, the inventors found that if the tool substrate is first subjected to Co removal treatment, the tool surface will become too smooth, making it impossible to grow sand on the tool substrate surface during the subsequent sandblasting process.

[0010] Optionally, the tool substrate is made of WC-Co cemented carbide, the particle size of the WC particles is 0.5-2.5 μm, and the Co content is 6-9 wt%; the micro-serrations at the cutting edge of the tool substrate are ≤0.003 mm; the surface roughness parameters are: the arithmetic mean deviation of the surface profile Ra ≤0.2 mm, the maximum height of the surface profile Rz ≤0.8 mm, and the average width of the surface profile unit Rsm ≤0.3 mm.

[0011] The tool substrate is prepared by controlling the grinding process to achieve a surface roughness that is consistent with no visible grinding marks. The technical solution described in this application effectively removes microscopic sawtooth formations during the grinding process, reduces stresses generated during deposition and machining, and effectively maintains cutting edge sharpness, lowering cutting resistance and improving performance and life.

[0012] Optionally, the soft rubber is selected from any one or both of butadiene rubber and styrene-butadiene rubber.

[0013] Optionally, the purity of the diamond powder is ≥99.999%.

[0014] Optionally, the specific process parameters of the soft abrasive sandblasting treatment are: the nozzle diameter of the sandblasting equipment is 10-30 mm, the angle between the nozzle and the tool axis is 30-45°, the distance between the nozzle and the tool axis is 30-80 mm, and the pressure of the soft abrasive flow ejected from the nozzle is 0.1-0.4 MPa; during the sandblasting impact process, the nozzle moves up and down along the tool axis at a speed of 0.5-6 mm / s, and the tool is driven by a motor to alternately rotate forward and reverse, with a speed range of 20-40 r / min; the forward and reverse time ratio range is 1:2-2:1.

[0015] In a specific embodiment, the cutting edge of the tool after the soft abrasive sandblasting treatment is smooth, has no serrations when detected under an 80-120 times optical microscope, and has a micro-bluntness of 0.002-0.004 mm.

[0016] The specific process parameters of the surface roughening are: using walnut or olive shell particles with a particle size of 0.5-2 mm, the surface of the tool is roughened for 50-70 seconds; the tool is driven by a motor to alternately rotate forward and reverse in the abrasive barrel, the speed range is 20-40 r / min, and the forward and reverse time ratio range is 1:2-2:1.

[0017] Using a drag-type tool treatment method, the tool is clamped upside down and placed in a drum of crushed walnut or olive shell particles. A motor drives the tool to rotate, creating friction with the abrasive, creating surface scratches. This is done for different tool sizes, with smaller tools requiring slower rotation and shorter rotation times. The forward and reverse rotations primarily affect the shape of the cutting edge, which is primarily related to the tool structure.

[0018] The present application forms uniform scratches with a depth of μm on the surface of the tool through a surface roughening method, which can effectively roughen the surface, reduce the surface energy, effectively increase the nucleation density, and improve the growth rate.

[0019] A more uniform surface contributes to the uniformity and uniformity of growth due to the competing growth mechanism, reducing grain boundary stresses caused by grain size differences.

[0020] This application quantitatively characterizes the surface state of the tool after edge treatment and surface roughness treatment by quantifying the surface roughness characteristic values ​​of the tool after edge treatment, thereby improving the repeatability and stability of the solution in industrial production.

[0021] Optionally, the surface roughness parameters of the tool after the surface roughening treatment are: arithmetic mean deviation of the surface profile Ra≤0.1 mm, maximum height of the surface profile Rz≤0.5 mm, and average width of the surface profile unit Rsm≤0.2 mm.

[0022] Optionally, the Co removal treatment method is an acid-base two-step method.

[0023] Optionally, the acid-base two-step method is specifically as follows: immersing the tool in an alkaline solution for ultrasonic treatment for 15-30 minutes to remove WC on the tool surface, and then immersing the tool in an acid solution for corrosion for 0.5-1.5 minutes to remove the cobalt element on the tool surface.

[0024] Optionally, the alkaline solution is potassium ferrocyanide, potassium hydroxide and purified water in a weight ratio of 1:1:10.

[0025] Optionally, the acid solution is hydrochloric acid and hydrogen peroxide in a volume ratio of 3:10.

[0026] In a specific embodiment, the tool after the Co removal treatment should meet the following characteristics: the surface Co content is 0.2-0.5%, and there is no pit caused by local Co loss.

[0027] Optionally, the Co removal treatment method further comprises placing the tool treated by the acid-base two-step method in a crystal planting solution and ultrasonically shaking for 30 minutes.

[0028] Optionally, the crystal planting solution is a mixed suspension of diamond powder and acetone in a weight ratio of (3-5):100.

[0029] The loose layer is removed and the diamond powder in the crystal planting solution remains on the surface, providing growth sites and increasing the initial growth density.

[0030] Optionally, the coating is deposited as follows: 4 groups of auxiliary anodes are arranged on the outside of the tool base, the auxiliary anodes are negatively charged compared to the hot wire and positively charged compared to the tool, the bias voltage between the auxiliary anode and the tool is 18-22V, and then the hot wire CVD method is used to deposit a diamond coating on the tool surface.

[0031] The specific process parameters of the hot-filament CVD method are: background vacuum ≤ 1 Pa, hot-filament temperature 2000-2200°C, tool substrate temperature 750-900°C, total gas flow rate 1000-3000 sccm, methane flow concentration 2%-6%, chamber pressure 1000-5000 Pa, and deposition time 8-16 hours. High vacuum levels are prone to impurities, while low vacuum levels place high demands on equipment. Low temperatures result in the growth of carbon ash, while high temperatures do not allow for growth. High pressures tend to grow larger diamonds, while low pressures produce smaller particles. Excessive or insufficient flow rates result in uneven growth.

[0032] This application adopts an auxiliary anode deposition method, which effectively reduces the coating cracking caused by tip discharge between the hot wire / tool ​​due to the sharp cutting edge, and uniformizes the flow field temperature field where the tool is located through the auxiliary anode, making the deposition effect more uniform.

[0033] The auxiliary anode deposition method is used to form a low-intensity stable directional electric field between the auxiliary anode and the tool, which promotes the ionization of CH3 + The groups are deposited on the tool surface, which increases the deposition rate.

[0034] In a second aspect, the present application provides a cutting tool with a submicron diamond coating, which is produced using the above-mentioned preparation method.

[0035] This application discloses a cutting tool with a submicron diamond coating, suitable for graphite roughing and finishing. The technical approach involves: first, a carbide cutting tool substrate with a defined roughness range and edge condition is obtained; then, the cutting tool is micro-passivated using a soft abrasive flow to remove microscopic sawtooth on the cutting edge; then, crushed walnut or olive shell particles are used as an abrasive to roughen the cutting tool surface, forming uniform, fine wear marks of a defined depth; finally, a dense, highly uniformly crystalline, and low-stress submicron diamond coating is deposited on the cutting tool surface using a hot-wire CVD method combined with multiple auxiliary anodes.

[0036] In a third aspect, the present application provides the use of the above-mentioned cutting tool with submicron diamond coating in graphite processing.

[0037] The present application can obtain a diamond-coated tool with both wear resistance and processing precision, and can perform rough and fine processing of graphite by changing processing parameters without changing the tool. It has a wide range of applicability and is applicable to tools of any shape. It has convenient, efficient and stable technical characteristics, and has broad market prospects and significant economic benefits.

[0038] In summary, the technical solution of this application has the following effects:

[0039] This application proposes a diamond coating with a submicron (500-1000nm) structure that is directly deposited on the surface of a tool. The coating particles are small but tightly arranged tetrahedral crystals. Due to the small particle size and relatively uniform arrangement, the surface roughness is significantly less than that of traditional micron coatings. At the same time, the growth mode is still columnar growth, and it has good adhesion ability.

[0040] The technical solution of the present application can achieve the purpose of simultaneously taking into account high wear resistance and low roughness. During use, it can reduce the number of tool changes and machine tool downtime, reduce tool use costs, improve processing efficiency, and improve economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a microscopic diagram of the initial structure of the tool substrate after grinding in Example 1 and a local diagram of the cutting edge.

[0042] Figure 2 Schematic diagram of the tool edge obtained after surface roughening in Example 1 ( Figure 2 a) and the cutting edge arc size test results ( Figure 2 b).

[0043] Figure 3 This is a surface morphology of the submicron diamond coating of the finished tool in Example 1.

[0044] Figure 4 This is the surface Raman spectrum detection result of the finished tool in Example 1.

[0045] Figure 5 Schematic diagram of tool edge wear after continuous graphite processing for 2 hours using the finished tool in Example 1. DETAILED DESCRIPTION

[0046] The present application is further described in detail below in conjunction with examples, comparative examples and performance testing experiments. These examples should not be construed as limiting the scope of protection claimed in this application.

[0047] Example

[0048] Example 1

[0049] Example 1 provides a method for preparing a cutting tool with a submicron diamond coating.

[0050] The method for preparing a tool with a submicron diamond coating in this embodiment comprises: preparing a tool substrate, performing soft abrasive sandblasting, surface roughening, Co removal, and coating deposition; the specific steps are:

[0051] (1) Preparation of tool substrate: The tool material used in this embodiment is K05, and the tool substrate is made of WC-Co cemented carbide. The particle size of the WC particles is 0.5-2.5 μm, and the Co content is 6-9 wt%. The tool shape is ground using a five-axis grinder and a fine-grained grinding wheel. The specifications after grinding are D4×20×60×SD4, which means a blade diameter of 4 mm, a blade length of 20 mm, a total length of 60 mm, and a shank diameter of 4 mm.

[0052] Check the tool after grinding, Figure 1This is a microscopic diagram of the initial structure of the tool substrate after grinding in Example 1 of the present application and a local diagram of the cutting edge (120×). The cutting edge of the tool substrate has no serrations or chips, and there are no visible grinding marks on the macro scale; the microscopic serrations at the cutting edge of the tool substrate are ≤0.003mm; the surface roughness parameters are: the arithmetic mean deviation of the surface profile Ra≤0.2mm, the maximum height of the surface profile Rz≤0.8mm, and the average width of the surface profile unit Rsm≤0.3mm. As can be seen from the microscopic diagram, after 120 times optical microscopy magnification, the cutting edge has obvious discontinuous serrated defects, which are caused by the abrasive grains of the grinding wheel during the grinding process and cannot be avoided. The serrations will further become larger during the acid-base corrosion process, resulting in microscopic local chipping, which will further cause the thermal stress to be concentrated at the chipping position during the deposition process, and the deposited coating will be locally discontinuous, which will lead to large thermal stress during the processing, high local temperature, and thus coating peeling and failure.

[0053] (2) Soft abrasive sandblasting: According to the weight ratio of 100:2.5, 1±0.1μm cis-butadiene rubber and 0.2±0.1μm diamond powder were uniformly mixed at 50°C to obtain sand material; the tool was clamped vertically and fixed on the tool disk of the sandblasting machine using a fixture, the nozzle diameter was selected to be 15mm, the angle between the nozzle and the tool axis was adjusted to 35°, and the distance between the nozzle and the tool axis was 40mm; the sandblasting pressure was set to 0.2MPa, and the nozzle was set to The up and down movement positions allow the tool blade to be completely covered; the sandblasting equipment is started, and the sand material is used as the medium, sucked into the compressed air pipe and sprayed from the nozzle onto the rotating tool surface. During the sandblasting impact process, the nozzle moves up and down along the tool axis at a speed of 3 mm / s. The tool is driven by a motor to alternately rotate forward and reverse, with a speed range of 30 r / min and a forward and reverse time ratio range of 1:2; it plays the role of grinding and polishing, and then the tool is taken out and the tool surface is wiped with anhydrous ethanol to remove residual diamond powder dust.

[0054] (3) Surface roughening: including primary roughening and secondary roughening, using olive shell particles with a particle size of 0.5-2 mm as abrasives; using a drag tool (equivalent to placing the tool head down in the sand and letting the tool rotate and revolve to stir the sand) processing method, using a fixture to clamp the tool, and placing the tool end down, lowering the tool position so that the blade is completely under the abrasive, starting the roughening equipment to control the tool rotation and the abrasive to produce relative friction to form scratches; the abrasive used in the primary roughening is walnut shell with a particle size of 1.5-2 mm, the tool relative to the abrasive speed is 20-40 r / min; the surface roughening time is 30 s; the abrasive used in the secondary roughening is olive shell with a particle size of 0.5-1 mm, the tool relative to the abrasive speed is 20-40 r / min; the surface roughening time is 30 s.

[0055] The tool was then taken out and the continuity and shape of the cutting edge were checked using Keyence's tool 3D profile measuring instrument. Figure 2 Schematic diagram of the tool edge obtained after surface roughening in Example 1 of the present application ( Figure 2 a) and the cutting edge arc size test results ( Figure 2 b). This treatment effectively eliminates serrations on the tool's cutting edge. The surface roughness parameters of the roughened tool are: surface profile arithmetic mean deviation Ra ≤ 0.1mm, maximum profile height Rz ≤ 0.5mm, and average width of surface profile units Rsm ≤ 0.2mm. As can be seen from the figure, the tool's cutting edge is remarkably continuous and smooth, with no discernible serrations. This effectively prevents stress concentration during machining caused by microscopic serrations, which can lead to coating peeling. Edge radius testing reveals a distinct 3μm radius transition on the treated cutting edge, ensuring sharpness while effectively enhancing edge strength and extending tool life.

[0056] (4) Co removal treatment: The tool was ultrasonically cleaned in an acetone solution, then taken out and dried. The tool was immersed in an alkaline solution (potassium ferrocyanide, potassium hydroxide and pure water in a weight ratio of 1:1:10) and ultrasonically treated for 30 minutes to remove WC on the tool surface. The tool was then immersed in an acid solution (hydrochloric acid and hydrogen peroxide in a volume ratio of 3:10) and corroded for 1 minute to remove the cobalt element on the tool surface. The tool was placed in a crystal planting solution (a mixed suspension of diamond micropowder and acetone in a weight ratio of 4:100) and ultrasonically vibrated for 30 minutes to remove the loose layer and allow the diamond micropowder in the crystal planting solution to remain on the surface, providing growth sites and increasing the initial growth density. The tool was then taken out and cleaned in anhydrous ethanol and acetone respectively, and then taken out and dried.

[0057] (5) Deposition coating: The tool is placed in the coating cavity and the coating is prepared. The complete coating preparation process is divided into two parts. The first part is the nucleation stage. The main reaction process in this stage is that the tool surface captures the ionized C-containing groups, and the attachment, surface diffusion, agglomeration and film formation are carried out based on the nucleation sites remaining in the crystal planting process. The main process parameters are: the first part is the initial growth, the background vacuum is ≤1Pa, the nucleation growth time is 0.5h, the hydrogen flow rate is 1200sccm, the methane flow rate is 40sccm, the reaction pressure is 2000Pa, and the tool substrate temperature is 750-900℃; the second part is the stable growth stage. The main reaction process is the columnar growth of diamond particles. The main process parameters are: growth time 12h, total gas flow rate 1200sccm, hydrogen flow rate 1000sccm, methane flow rate 48sccm (concentration 4%), reaction pressure 4000Pa, and tool substrate temperature 780-850℃.

[0058] Example 2-3

[0059] Examples 2-3 respectively provide a method for preparing a cutting tool having a submicron diamond coating.

[0060] The difference between the above embodiment and embodiment 1 is that the preparation method of the sand material in the soft abrasive sandblasting process is as follows:

[0061] In Example 2, butadiene rubber soft rubber with a particle size of 0.6±0.1 μm and diamond powder with a particle size of 0.3±0.1 μm were uniformly mixed at 50° C. in a weight ratio of 100:1 to obtain sand material.

[0062] In Example 3, butadiene rubber soft rubber with a particle size of 1.4±0.1 μm and diamond powder with a particle size of 0.4±0.1 μm were uniformly mixed at a weight ratio of 100:5 at 50° C. to obtain sand material.

[0063] In Example 4, styrene-butadiene rubber soft rubber with a particle size of 1±0.1 μm and diamond powder with a particle size of 0.2±0.1 μm were uniformly mixed at 50° C. in a weight ratio of 100:2.5 to obtain sand material.

[0064] The remaining steps of the above embodiment are the same as those of embodiment 1.

[0065] Examples 5-11

[0066] Examples 5-11 respectively provide a method for preparing a cutting tool having a submicron diamond coating.

[0067] The difference between the above embodiment and embodiment 1 is that the coating deposition process is different, specifically:

[0068] In Example 5, a hot-filament CVD method was used to deposit a diamond coating on the surface of the tool (without combining multiple auxiliary anodes).

[0069] In Example 6, the bias voltage between the auxiliary anode and the tool is 16V.

[0070] In Example 7, the bias voltage between the auxiliary anode and the tool is 24V.

[0071] In Example 8, the total gas flow rate is 1200 sccm, the hydrogen flow rate is 1000 sccm, and the methane flow rate is 24 sccm (concentration 4%).

[0072] In Example 9, the total gas flow rate is 1200 sccm, the hydrogen flow rate is 1000 sccm, and the methane flow rate is 72 sccm (concentration 6%).

[0073] In Example 10: the total gas flow rate is 1200 sccm, the hydrogen flow rate is 1000 sccm, and the methane flow rate is 78 sccm (concentration 6%).

[0074] In Example 11: the total gas flow rate is 1200 sccm, the hydrogen flow rate is 1000 sccm, and the methane flow rate is 18 sccm (concentration 1.5%).

[0075] The remaining steps of the above embodiment are the same as those of embodiment 1.

[0076] Comparative Example

[0077] Comparative Examples 1-3

[0078] Comparative Examples 1-3 respectively provide a method for preparing a cutting tool.

[0079] The difference between the comparative example and Example 1 is that the preparation method of the sand material in the soft abrasive sandblasting treatment is as follows:

[0080] In Comparative Example 1, diamond micropowder with a particle size of 5-10 μm and resin particles with a particle size of 60-80 mesh were uniformly mixed in a weight ratio of 1:4, and ultrasonically treated in glycerol for 45 minutes to obtain a sand material.

[0081] In Comparative Example 2, butadiene rubber soft rubber with a particle size of 1±0.1 μm and diamond powder with a particle size of 0.2±0.1 μm were uniformly mixed at a weight ratio of 100:0.5 at 50° C. to obtain sand material.

[0082] In Comparative Example 3, butadiene rubber soft rubber with a particle size of 1±0.1 μm and diamond powder with a particle size of 0.2±0.1 μm were uniformly mixed at a weight ratio of 100:5.5 at 50° C. to obtain sand material.

[0083] The remaining steps of the above comparative example are the same as those of Example 1.

[0084] Performance testing

[0085] (1) Surface morphology detection: EmCrafts CUBE-ⅡPlus electron microscope and energy dispersive spectrometer.

[0086] Figure 3 This is a surface morphology image (SEM) of the submicron diamond coating of the finished tool in Example 1 of the present application.

[0087] Depend on Figure 3 From the morphology diagram, it can be seen that the diamond morphology on the surface of the tool is uniform, the arrangement is tight, the crystal orientation is uniform, and they all have obvious 111 face orientation. The particles are tightly arranged without gaps or agglomerations, indicating that the tool with submicron diamond coating prepared in this application has good wear resistance and impact resistance.

[0088] (2) Spectral detection: Swiss Metrohm laser Raman spectrometer.

[0089] The diamond composition on the tool surface was detected based on Raman spectroscopy. The results are as follows: Figure 4 As shown, Figure 4 This is the surface Raman spectrum detection result of the finished tool in Example 1 of the present application.

[0090] As can be seen from the figure, a sharp indicator peak is only observed near the diamond standard peak 1332, indicating that the coating contains significant SP3 content, high purity, and excellent wear resistance. The small offset from the standard peak indicates that the coating has low internal stress. Raman spectroscopy is an important technical method for characterizing the quality of diamond coatings. The spectral results show that within the wide wavenumber range of 1-1800, there is only a sharp indicator peak near the diamond standard peak 1332, indicating that the coating contains high-purity diamond components. The small offset from the standard peak indicates that the coating has low internal stress and good impact resistance and toughness.

[0091] (3) Schematic diagram of tool edge wear in tool processing test

[0092] After checking that there are no appearance defects such as chipping on the surface, a processing test is carried out. The test machine model is CARVER 600T, the rough machining parameters are ap=1mm, ae=3mm, the speed is 6500r / min, the feed is 2200mm / min, and the continuous machining time is 2 hours. After that, the surface finishing is carried out without changing the tool. The rough machining parameters are ap=1mm, ae=3mm, the speed is 6500r / min, and the feed is 2200mm / min. After that, the surface finishing is carried out with the machining parameters of ap=0.1mm, ae=3mm, the speed is 12000r / min, and the feed is 4000mm / min.

[0093] After the processing, the surface of the graphite block is checked to be smooth and the tool edge is worn. Figure 5 As shown, Figure 5 Schematic diagram of tool edge wear after continuous graphite processing for 2 hours using the finished tool in Example 1.

[0094] As shown in the figure, after machining graphite using the finished tool of Example 1, the tool wear is uniform and free of chipping. The wear position is continuous and smooth, with no coating peeling or chipping. The wear loss is only 0.02 mm, far less than the normal wear standard of 0.2. This shows that the tool with a submicron diamond coating obtained according to this application can effectively perform rough and fine machining of graphite, reduce the number of tool changes, and improve machining efficiency.

[0095] (4) The surface roughness, mechanical properties and friction properties of the tool samples prepared in the examples and comparative examples were tested:

[0096] The surface roughness (Ra) of the cutting tool samples was measured using an Axio CSM700 Zeiss white light confocal microscope with a measurement area of ​​2.5×10 5 μm 2 .

[0097] The NanoTest Vantage system was used to test the surface hardness (H) of the tool samples. The indentation depth did not exceed 10% of the coating thickness. Six points were randomly selected and the average value was taken.

[0098] The friction force and friction coefficient of the tool sample coating were detected using the reciprocating mode of the friction and wear testing machine. The loading force was 5N, the frequency was 200Hz, the reciprocating length was 10mm, and the experimental test time was 5min.

[0099] Test results: as shown in Table 1.

[0100] Table 1 Performance test results of the cutting tools in Examples 1-11 and Comparative Examples 1-3

[0101]

[0102] It can be seen from the test results in Table 1 that using the preparation method provided in this application, a tool with a submicron diamond coating having a surface roughness of ≤0.495 μm, a surface hardness of ≥75.721 GPa, and a friction coefficient of 0.032-0.056 was prepared, indicating that the tool prepared in this application has better surface hardness and wear resistance.

[0103] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for preparing a cutting tool with a submicron diamond coating, characterized in that: The specific steps include: Preparation of tool substrate, soft abrasive sandblasting, surface roughening, Co removal, and coating deposition; The soft abrasive sandblasting treatment comprises: uniformly mixing butadiene rubber with a particle size of 0.5-1.5 μm and diamond micropowder with a particle size of 0.1-0.5 μm at a weight ratio of 100:(1-5) at the softening temperature of the butadiene rubber to obtain abrasive material, and sandblasting the surface of the tool substrate using a directional jet of air as a medium; The coating deposition is as follows: 4 groups of auxiliary anodes are arranged on the outside of the tool base, the auxiliary anodes are at a negative potential compared to the hot wire and at a positive potential compared to the tool, the bias voltage between the auxiliary anodes and the tool is 18-22V, and then a hot wire CVD method is used to deposit a diamond coating on the tool surface; the specific process parameters of the hot wire CVD method are: background vacuum ≤1Pa, hot wire temperature 2000-2200℃, tool substrate temperature 750-900℃, total gas flow 1000-3000sccm, methane flow concentration 2%-6%, pressure in the reaction chamber 1000-5000Pa, and deposition time 8-16h.

2. The method for preparing a cutting tool having a submicron diamond coating according to claim 1, characterized in that: The tool substrate is made of WC-Co cemented carbide, the WC particle size is 0.5-2.5μm, and the Co content is 6-9wt%; the micro-serrations at the cutting edge of the tool substrate are ≤0.003mm; the surface roughness parameters are: the arithmetic mean deviation of the surface profile Ra≤0.2mm, the maximum height of the surface profile Rz≤0.8mm, and the average width of the surface profile unit Rsm≤0.3mm.

3. The method for preparing a cutting tool having a submicron diamond coating according to claim 1, characterized in that: The specific process parameters of the soft abrasive sandblasting treatment are as follows: the nozzle diameter of the sandblasting equipment is 10-30 mm, the angle between the nozzle and the tool axis is 30-45 degrees, the distance between the nozzle and the tool axis is 30-80 mm, and the pressure of the soft abrasive flow ejected through the nozzle is 0.1-0.4 MPa; during the sandblasting impact process, the nozzle moves up and down along the tool axis at a speed of 0.5-6 mm / s, the tool is driven by a motor to alternately rotate forward and reverse, and the speed range is 20-40 r / min; the forward and reverse time ratio range is 1:2-2:

1.

4. The method for preparing a cutting tool with a submicron diamond coating according to claim 1, characterized in that: The specific process parameters of the surface roughening are: using walnut or olive shell particles with a particle size of 0.5-2 mm, the surface of the tool is roughened for 50-70 seconds; the tool is driven by a motor to alternately rotate forward and reverse in the abrasive barrel, the speed range is 20-40 r / min, and the forward and reverse time ratio range is 1:2-2:

1.

5. The method for preparing a cutting tool with a submicron diamond coating according to claim 1, characterized in that: The surface roughness parameters of the tool after the surface roughening treatment are: surface profile arithmetic mean deviation Ra≤0.1mm, surface profile maximum height Rz≤0.5mm, and surface profile unit average width Rsm≤0.2mm.

6. A cutting tool with a submicron diamond coating, characterized in that: The method is prepared according to any one of claims 1 to 5.

7. Use of the cutting tool with submicron diamond coating as claimed in claim 6 in graphite processing.

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