Preparation method of HiPIMS coating adaptive to multi-grain-size hard alloy and hard alloy cutting tool of HiPIMS coating

Abstract

The invention relates to the technical field of hard alloy coating preparation, and discloses a preparation method of a HiPIMS coating adaptive to multi-grain-size hard alloy and a hard alloy cutting tool thereof. The preparation method of the HiPIMS coating adaptive to the multi-grain-size hard alloy comprises the main steps of vacuumizing, heating and heat preservation, argon glow discharge plasma etching and cleaning, arc electron source auxiliary cleaning and activation, and metal nitride coating deposition on the surface of a base material through the high-power pulse magnetron sputtering technology. According to the preparation method disclosed by the invention, the preparation of the metal nitride coatings on the hard alloy substrates with different grain sizes is realized, and the prepared metal nitride coatings have relatively high hardness and adhesive force, so that the problem that process parameters of hard alloys with different grain sizes need to be independently optimized in the prior art is solved; and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coating preparation, and in particular to a HiPIMS coating preparation method adapted for multi-grain-size cemented carbide and a cemented carbide cutting tool thereof. Background Art

[0002] Due to its excellent hardness, wear resistance and high-temperature stability, cemented carbide is widely used in cutting tools, molds and wear-resistant parts. However, due to the differences in the grain size of traditional cemented carbide workpieces, the surface energy, porosity and chemical activity of the coating will show significant differences. Traditional physical vapor deposition (PVD) technology faces significant limitations when processing cemented carbide with multiple grain sizes. On the one hand, it needs to optimize the process parameters according to the different grain sizes of the cemented carbide, resulting in low production efficiency. On the other hand, due to the difference in surface energy between the coating and the cemented carbide substrate with larger grain size, stress concentration at the grain boundary leads to a large dispersion of the coating hardness, resulting in uneven adhesion during coating deposition, easy coating peeling, large hardness fluctuations and other problems. High-power impulse magnetron sputtering (HiPIMS) is a novel magnetron sputtering technology that combines magnetron sputtering with pulsed discharge. It can achieve non-melting of the target material and high ionization of the sputtered particles under conditions of extremely high transient applied power density. The dense and smooth coatings deposited using HiPIMS have led to its continued development in recent years. However, the process parameters of HiPIMS are sensitive to substrate grain size, making it difficult to adapt existing HiPIMS processes to cemented carbide substrates of varying grain sizes within a single process window.

[0003] Currently, coating technologies for multi-grain carbide often rely on step-by-step or composite processes, but these methods suffer from complex processes, high costs, and poor coating consistency. Therefore, there is an urgent need to develop a simple HiPIMS coating preparation method suitable for multi-grain carbide. This method can achieve uniform nucleation and growth of the coating on hard substrates with different grain sizes, while ensuring high hardness and strong adhesion. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing HiPIMS coatings suitable for cemented carbide with multiple grain sizes.

[0005] The technical solution of the present invention is:

[0006] A method for preparing a HiPIMS coating adapted to cemented carbide with multiple grain sizes, characterized by comprising the following steps:

[0007] S1. Vacuuming and heating

[0008] The substrate surface is ultrasonically cleaned and dried, placed on a sample turntable in the chamber, vacuumed, and heated;

[0009] S2, Argon Glow Discharge Plasma Etching Cleaning

[0010] Ar is introduced into the cavity, the pressure in the cavity is maintained at 0.5-1.5 Pa, a pulse bias power supply is started, the bias voltage is 700V-1000V, the bias duty cycle is 50%-80%, and the cleaning time is 15-20 minutes. The substrate is etched and cleaned by using argon ions generated under high bias voltage;

[0011] S3, arc electron source assisted cleaning and activation

[0012] Maintain the pressure in the chamber at 0.5-1.5 Pa, turn on the main power supply of the arc electron source, set the parameters of the arc power supply and bias power supply, use the electron flow to activate the argon atoms to generate plasma, and activate the workpiece surface;

[0013] S4. Metal nitride coating deposition

[0014] A working gas is introduced into the cavity to maintain a stable gas pressure in the cavity, and a HiPIMS system power supply is applied to the target material. The HiPIMS system power supply parameters include: a target voltage of 400V to 600V, a target current of 150A to 250A, an average power of 4.0 to 8.0kW, a frequency of 350 to 550Hz, and a pulse width of 100 to 300μs. The substrate is treated with a metal nitride coating using HiPIMS technology for a coating time of 1 to 4 hours to obtain a metal nitride coating on the surface of the substrate.

[0015] The metal nitride coating is a nitride layer of one or more of Ti, Al, Si, Ta, Cr, Zr, and C;

[0016] S5. Cooling sampling

[0017] After the coating is completed, turn off the power, cool the furnace to room temperature under vacuum and then take out the workpiece sample.

[0018] Furthermore, the substrate is a YG cemented carbide substrate with different grain sizes, which includes:

[0019] An ultrafine-grained YG cemented carbide substrate, wherein the WC grain size of the ultrafine-grained YG cemented carbide substrate is 0.3-0.5 μm; a fine-grained YG cemented carbide substrate, wherein the WC grain size of the fine-grained YG cemented carbide substrate is 0.5-0.8 μm; and a medium-grained YG cemented carbide substrate, wherein the WC grain size of the medium-grained YG cemented carbide substrate is 0.8-1.5 μm.

[0020] Furthermore, during the vacuuming and heating in step S1, the temperature is heated to 300-400° C. and kept warm for 15-25 minutes.

[0021] Furthermore, in the S3 arc electron source assisted cleaning and activation step, the arc electron source main power current is 70A~100A, the arc electron source auxiliary anode current is 30A~40A, the bias is 100V~300V, the bias duty cycle is 50%~80%, and the cleaning time is 15~20min.

[0022] Furthermore, in the S4 metal nitride coating deposition step, the target material includes one or more of a TiAl target and a TiSi target.

[0023] Furthermore, in step S4, the working gases are N2 and Ar, the flow ratio of N2 to Ar is (0.3-0.8:1), the total flow range of the working gases is 200-300 SCCM, and the gas pressure in the cavity is maintained at 0.5 Pa.

[0024] Furthermore, the thickness of the metal nitride coating of the workpiece sample is 700-800 nm, the hardness of the metal nitride coating is ≥30 GPa, and the adhesion of the metal nitride coating is ≥120N.

[0025] The present invention provides a hardware alloy cutting tool, characterized in that it is prepared by using any of the above-mentioned methods for preparing a HiPIMS coating adapted to multi-grain-size cemented carbide.

[0026] Furthermore, the hardware alloy cutting tool comprises a cemented carbide substrate, and the cemented carbide substrate is plated with a metal nitride coating;

[0027] The cemented carbide substrate is WC-Co cemented carbide, wherein the Co content is 10% and the WC grain size is 0.3 to 1.5 μm;

[0028] The metal nitride coating is a nitride layer of one or more of Ti, Al, and Si.

[0029] Furthermore, the metal nitride coating is a TiAlN coating, the thickness of the TiAlN coating is 700-800 nm, and the TiAlN coating comprises 18-22% Ti, 28-34% Al, and 44-50% N in atomic percentage.

[0030] The beneficial technical effects of the present invention are:

[0031] 1. The HiPIMS coating preparation method provided by the present invention is suitable for the preparation of metal nitride coatings on cemented carbides with different grain sizes, and the prepared metal nitride coating has high hardness and adhesion, overcoming the problem in the prior art of requiring separate optimization of process parameters for cemented carbides with different grain sizes, thereby improving production efficiency.

[0032] 2. The present invention adopts a two-stage plasma cleaning and activation method. First, the oxide layer on the substrate surface is removed by high-bias argon ion etching. Then, the surface of the cemented carbide substrate is activated by low-temperature, high-density plasma generated by an arc electron source. This creates a uniform, atomically clean surface on the substrate. At the same time, the plasma bombardment causes the surface of the cemented carbide substrate to heat up and produce pit-like points, which is conducive to the uniform nucleation of coating atoms on the surface of the cemented carbide substrate and reduces the influence of the grain size differences of the cemented carbide substrate itself on the nucleation of coating ions.

[0033] 3. The present invention achieves a high ionization rate of the sputtering target by controlling the power supply parameters of the HiPIMS system. At the same time, by controlling the total flow rate of the working gas N2 / Ar and the flow ratio of N2 and Ar, and maintaining the gas pressure in the chamber at 0.5Pa, the chemical adsorption balance on the surface of cemented carbide substrates with different grain sizes is achieved, the kinetic energy of the sputtered ions flying to the surface of the cemented carbide substrate is ensured to be stable, and the coating ion penetration depth is adapted to the interface bonding requirements of submicron to micron grains, so as to achieve ultrafine-grained cemented carbide substrates (WC grain size of 0.3~0.5μm), fine-grained cemented carbide substrates (WC grain size of 0.5~0.8μ) and medium-grained cemented carbide substrates (WC grain size of 0.8~1.5μm) under the same HiPIMS coating preparation process conditions provided by the present invention. A metal nitride layer with high hardness (≥30GPa) and high adhesion (≥120N) can be plated. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 (a) is the surface morphology of the TiAlN coating in Example 1;

[0035] Figure 1 (b) is the surface morphology of the TiAlN coating of Example 2;

[0036] Figure 1 Middle (c) is the surface morphology of the TiAlN coating of Example 3;

[0037] Figure 1 Middle (d) is the surface morphology of the TiAlN coating of comparative example 1;

[0038] Figure 1 Middle (e) is the surface morphology of the TiAlN coating of comparative example 2;

[0039] Figure 1Middle (f) is the surface morphology of the TiAlN coating of comparative example 3;

[0040] Figure 2 1 is a comparison chart of the microhardness of the coatings of Examples 1-3 and Comparative Examples 1-3 measured by nanoindentation testing;

[0041] Figure 3 (a) is a surface scratch test image of the TiAlN coating in Example 1;

[0042] Figure 3 (b) is a surface scratch test image of the TiAlN coating in Example 2;

[0043] Figure 3 Middle (c) is a surface scratch test image of the TiAlN coating of Example 3;

[0044] Figure 3 Middle (d) is a surface scratch test image of the TiAlN coating of Comparative Example 1;

[0045] Figure 3 Middle (e) is a surface scratch test image of the TiAlN coating of comparative example 2;

[0046] Figure 3 Middle (f) is a surface scratch test picture of the TiAlN coating of comparative example 3. DETAILED DESCRIPTION

[0047] In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0048] Example 1

[0049] This embodiment 1 provides a method for preparing a HiPIMS coating adapted to cemented carbide with multiple grain sizes, comprising the following steps:

[0050] S1. Vacuuming and heating

[0051] In Example 1, an ultrafine-grained YG cemented carbide substrate was selected, wherein the WC grain size in the ultrafine-grained YG cemented carbide substrate was 0.4 μm and the Co content was 10%;

[0052] The surface of the substrate was cleaned with an ultrasonic cleaner at a frequency of 40 kHz for 20 min, the substrate was taken out, and the surface of the substrate was blown dry with compressed argon gas with a purity of 99.999%. The substrate after the above treatment was placed on the sample rotating rack in the cavity, and the cavity was evacuated to a vacuum degree of 3.0×10 -3Pa, heated to 400 ° C and kept warm for 20 minutes, the sample turret adopts a planetary turret, the revolution speed is 1.5 r / min, and the sample rotation speed is 8 r / min.

[0053] S2, Argon Glow Discharge Plasma Etching Cleaning

[0054] Argon gas is introduced into the cavity to maintain the gas pressure in the cavity at 1.2 Pa, and a pulse bias voltage of 800 V is applied with a duty cycle of 80%. The substrate is etched and cleaned using argon ion plasma generated under the high bias voltage.

[0055] S3, arc electron source assisted cleaning and activation

[0056] The pressure in the cavity was adjusted to 0.6 Pa, the arc electron source was turned on, the main current was set to 80 A, the auxiliary anode current was set to 35 A, a bias voltage of 200 V was applied, the duty cycle was 80%, and the electron flow was used to activate argon atoms to generate plasma to perform surface activation on the substrate for 20 minutes.

[0057] S4. Metal nitride coating deposition

[0058] A working gas is introduced into the cavity, where the total flow rate of the two working gases is 260 SCCM, of which N2 accounts for 50%. A HiPIMS system power supply is applied to the target material, and the target material is a TiAl target material with an equimolar ratio. The parameters of the HiPIMS system power supply applied to the TiAl target material include: power supply mode medium frequency, target voltage 500 V, target current 200 A, average power 6.2 kW, pulse frequency 500 Hz, pulse width 150 μs, and deposition for 2 h under a gas pressure of 0.5 Pa to obtain a TiAlN coating on the surface of the substrate.

[0059] S5. Cooling sampling

[0060] After the coating is completed, the power is turned off and the workpiece sample is removed after cooling to room temperature in a vacuum state. The workpiece sample can be used as a cemented carbide cutting tool. The thickness of the TiAlN coating on the workpiece sample was measured to be 730nm. The TiAlN coating includes 20% Ti, 30% Al and 50% N in atomic percentage. The hardness of the TiAlN coating is 34.54GPa (measured by a nanoindenter). The scratch load is 150N without peeling. The surface morphology and cross-sectional view of the TiAlN coating are shown in the figure below. Figure 1 As shown in (a).

[0061] Example 2

[0062] Compared with Example 1, Example 2 differs in that the selected substrate is different, and the other process conditions are the same. The substrate selected in Example 2 is: a fine-grained YG cemented carbide substrate, the WC grain size in the fine-grained YG cemented carbide substrate is 0.8 μm, and the Co content is 10%; the TiAlN coating thickness of Example 2 is 719 nm, and the TiAlN coating includes 18% Ti, 32% Al, and 50% N in atomic percentage. The hardness of the TiAlN coating is 32.68 GPa, and it does not peel off under a scratch load of 150 N. The cross-sectional morphology of the coating surface is shown in FIG. Figure 1 (b) shown.

[0063] Example 3

[0064] Compared with Example 1, Example 3 differs in that the selected substrate is different, and the other process conditions are the same. The substrate selected in Example 3 is: a medium-grained YG cemented carbide substrate, wherein the WC grain size in the medium-grained YG cemented carbide substrate is 1.2 μm and the Co content is 10%; the thickness of the TiAlN coating in Example 3 is 704 nm, and the TiAlN coating includes 22% Ti, 30% Al and 48% N in atomic percentage. The hardness of the TiAlN coating is 32.59 GPa, and it does not peel off under a scratch load of 150 N. The cross-sectional morphology of the coating surface is shown in FIG. Figure 1 (c) shown.

[0065] Example 4

[0066] Example 4 differs from Example 1 in that, during the S4 metal nitride coating deposition step, the HiPIMS system power parameters applied to the TiAl target include: medium frequency power mode, target voltage of 600 V, target current of 250 A, average power of 7.5 kW, pulse frequency of 550 Hz, pulse width of 200 μs, and deposition for 3 hours at a gas pressure of 0.5 Pa, to form a TiAlN coating on the substrate surface. The TiAlN coating in Example 4 has a thickness of 800 nm and comprises, by atomic percentage, 22% Ti, 34% Al, and 44% N. The TiAlN coating has a hardness of 34.50 GPa and withstands a scratch load of 150 N without peeling.

[0067] Example 5

[0068] Example 5 differs from Example 1 in that, during the S3 arc electron source-assisted cleaning and activation step, the chamber pressure was adjusted to 1.0 Pa, the arc electron source was activated, the main current was set to 100 A, the auxiliary anode current was set to 40 A, a 250 V bias voltage was applied, and a duty cycle was set to 50%. Electrons were used to activate argon atoms to generate plasma, and the substrate surface was activated for 20 minutes. The TiAlN coating in Example 5 had a thickness of 730 nm and comprised, by atomic percentage, 20% Ti, 30% Al, and 50% N. The TiAlN coating had a hardness of 34.60 GPa and did not peel off after a scratch load of 150 N.

[0069] Example 6

[0070] Compared with Example 1, Example 6 differs in that: in the S4 metal nitride coating deposition step, the target material is a TiSi target material with an equimolar ratio, the thickness of the TiSiN coating in Example 4 is 740 nm, the TiSiN coating includes 37.8% Ti, 9.8% Si and 52.4% N in atomic percentage, the hardness of the TiSiN coating is 36 GPa, and it does not peel off under a scratch load of 150 N.

[0071] Comparative Example 1

[0072] Comparative Example 1 differs from Example 1 in that: there is no S3 arc electron source assisted cleaning and activation step, and the other process conditions are consistent with Example 1. The thickness of the TiAlN coating in Comparative Example 1 is 730 nm, and the TiAlN coating includes 20% Ti, 30% Al and 50% N in atomic percentage. The hardness of the TiAlN coating is 23.31 GPa. During the linear loading process of the scratch load of 100 N, the coating peels off at 92 N. The cross-sectional morphology of the coating surface is shown in the figure. Figure 1 (d) shown.

[0073] Comparative Example 2

[0074] Comparative Example 2 differs from Example 2 in that the working gases include N2 and Ar, with a total flow rate of 350 SCCM, of which N2 accounts for 25%. The remaining process conditions are consistent with those described in Example 2. The thickness of the TiAlN coating in Comparative Example 2 is 650 nm. The TiAlN coating includes 31% Ti, 40% Al, and 29% N in atomic percentage. The hardness of the TiAlN coating is 19.25 GPa. During a linear scratch load of 100 N, the coating peels off at 95 N. The cross-sectional morphology of the coating surface is shown in the figure below. Figure 1 (e) shown.

[0075] Comparative Example 3

[0076] Comparative Example 3 is different from Example 3 in that, in the deposition of the metal nitride coating in step S4, the HiPIMS power parameters applied to the target include: medium frequency power mode, target voltage 500V, target current 100A, average power 3.3kW, pulse frequency 500Hz, pulse width 150μs, and the other process conditions are the same. The thickness of the TiAlN coating in the comparative example is 486nm. The TiAlN coating includes 15% Ti, 25% Al and 60% N in atomic percentage. The hardness of the TiAlN coating is 18.88GPa. During the linear loading process of the scratch load of 100N, the coating peels off at 90N. The cross-sectional morphology of the coating surface is shown in the figure. Figure 1 (f) shown.

[0077] Figure 2 This is a comparison chart of the nanoindentation microhardness of the coatings of Examples 1-3 and Comparative Examples 1-3, which are measured using a nanoindenter. In the nanoindentation continuous stiffness mode, the indentation depth does not exceed one tenth of the coating.

[0078] Figure 3 (ac) correspond to the surface scratch morphology of the TiAlN coating of Examples 1-3, respectively. Figure 3 (df) correspond to the surface scratch morphology images of the TiAlN coatings of Comparative Examples 1-3, respectively. The scratch test was performed using a multifunctional surface tester with a Rockwell indenter HRC-3, a scratch length of 5 mm, a loading rate of 70 N / min, and load termination according to the coating adhesion. The loads included 150 N and 100 N. In the automatic continuous loading mode, when the scratch was loaded until the coating peeled off, the load value was considered to be the adhesion of the coating. This quantitatively evaluated the adhesion of the TiAlN coatings of Examples 1-3 and Comparative Examples 1-3.

[0079] from Figure 1 From the cross-sectional morphology of the TiAlN coatings of Examples 1-3 in (ac), it can be seen that the grain size of the substrate has a certain influence on the microscopic morphology of the coating. As the grain size of the substrate increases, the coating is more likely to show grain morphology. Figure 1 As shown in (ac), although the grain sizes of the cemented carbide substrates used in Examples 1-3 are quite different, the grain sizes of the coatings deposited on the cemented carbide substrates in Examples 1-3 are all small and evenly distributed. Figure 1 As shown in (df), the coating grain nucleation distribution in Comparative Example 1 is uniform, but the average particle size is larger. The coating grains in Comparative Example 2 are flat, agglomerated particles with a larger particle size and a more uniform distribution. The coating grains in Comparative Example 3 are evenly distributed, but the coating grain morphology is transformed into a conical flake, and the coating grain state changes significantly.

[0080] Combined with the above Figure 2 and Figure 3 The test results show that the hardness difference between the TiAlN coatings of Examples 1-3 is not obvious, and all have a high hardness (>30GPa). In addition, the TiAlN coatings of Examples 1-3 do not peel off when scratched under a load of 150N, and all three TiAlN coatings have a high adhesion (>120N). This shows that the HiPIMS coating preparation method of the present application takes into account the preparation of coatings adapted to cemented carbides with multiple grain sizes, and the mechanical properties of the coatings prepared are excellent and stable, overcoming the disadvantage of the prior art that different process parameters need to be adjusted for cemented carbides with different grain sizes, thereby improving production efficiency.

[0081] Combining the performance test results of Comparative Example 1 and Example 1, it can be seen that Comparative Example 1 cancels the arc electron source plasma cleaning and activation step, resulting in poor hardness and adhesion of the TiAlN coating of Comparative Example 1, and its TiAlN coating hardness is 23.31GPa; during the linear loading process of the scratch load 100N, the coating peels off at 92N. The reason for this is analyzed to be that: the bombardment of the plasma during the arc electron source plasma cleaning and activation process causes the surface of the cemented carbide substrate to heat up and produce pit-like points, which is conducive to the uniform nucleation of coating atoms on the surface of the cemented carbide substrate, reducing the influence of the grain size difference of the cemented carbide substrate itself on the coating ion nucleation, and ultimately helping to improve the adhesion and hardness of the coating.

[0082] Combining the performance test results of Comparative Example 2 and Example 2, it can be seen that the total working gas flow rate of 350 SCCM in Comparative Example 2 is too large, and the proportion of N2 is low, which also makes the coating hardness and adhesion poor. The hardness of its TiAlN coating is 19.25 GPa. During the linear loading process of 100N scratch load, the coating peels off at 95N. The reason is analyzed as follows: the total flow rate of working gas N2 / Ar and the flow ratio of N2 and Ar affect the percentage of Ti, Al and N in the TiAlN coating. Only when the percentage of Ti, Al and N in the TiAlN coating are all within a specific composition range (Ti 18-22%, Al 28-34% and N 44-50%), the TiAlN coating can have a higher hardness.

[0083] Combining the performance test results of Comparative Example 3 and Example 3, it can be seen that the hardness of the TiAlN coating in Comparative Example 3 is 18.88 GPa. During the linear loading process of the scratch load of 100 N, the coating peels off at 90 N. The reason for this is that the target current in Comparative Example 3 is 100 A and its average power is 3.3 kW, both of which are outside the HiPIMS system power supply parameter range defined in the present invention. That is, the target current and average power values ​​are both low, which makes the target material sputtering ability weak, and the kinetic energy of the sputtering ions flying to the surface of the cemented carbide substrate is unstable, which makes the target material ion penetration depth not compatible with the interface bonding requirements of the grains, which directly leads to poor coating hardness and adhesion.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit 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 technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a HiPIMS coating suitable for cemented carbide with multiple grain sizes, characterized in that: The steps include: S1. Vacuuming and heating The substrate surface is ultrasonically cleaned and dried, placed on a sample turntable in the chamber, vacuumed, and heated; S2, Argon Glow Discharge Plasma Etching Cleaning Ar is introduced into the cavity, the pressure in the cavity is maintained at 0.5-1.5 Pa, a pulse bias power supply is started, the bias voltage is 700V-1000V, the bias duty cycle is 50%-80%, and the cleaning time is 15-20 minutes. The substrate is etched and cleaned by using argon ions generated under high bias voltage; S3, arc electron source assisted cleaning and activation Maintain the pressure in the chamber at 0.5-1.5 Pa, turn on the main power supply of the arc electron source, set the parameters of the arc power supply and bias power supply, use the electron flow to activate the argon atoms to generate plasma, and activate the workpiece surface; S4. Metal nitride coating deposition A working gas is introduced into the cavity to maintain a stable gas pressure in the cavity, and a HiPIMS system power supply is applied to the target material. The HiPIMS system power supply parameters include: a target voltage of 400V to 600V, a target current of 150A to 250A, an average power of 4.0 to 8.0kW, a frequency of 350 to 550Hz, and a pulse width of 100 to 300μs. The substrate is treated with a metal nitride coating using HiPIMS technology for a coating time of 1 to 4 hours to obtain a metal nitride coating on the surface of the substrate. The metal nitride coating is a nitride layer of one or more of Ti, Al, Si, Ta, Cr, Zr, and C; S5. Cooling sampling After the coating is completed, turn off the power, cool the furnace to room temperature under vacuum and then take out the workpiece sample.

2. The method for preparing a HiPIMS coating adapted to cemented carbide with multiple grain sizes according to claim 1, characterized in that: The substrate is a YG cemented carbide substrate with different grain sizes, including: an ultrafine-grained YG cemented carbide substrate, the WC grain size of the ultrafine-grained YG cemented carbide substrate is 0.3-0.5 μm; a fine-grained YG cemented carbide substrate, the WC grain size of the fine-grained YG cemented carbide substrate is 0.5-0.8 μm; and a medium-grained YG cemented carbide substrate, the WC grain size of the medium-grained YG cemented carbide substrate is 0.8-1.5 μm.

3. The method for preparing a HiPIMS coating suitable for cemented carbide with multiple grain sizes according to claim 1, characterized in that: During the vacuuming and heating in S1, the temperature is heated to 300-400° C. and kept warm for 15-25 minutes.

4. The method for preparing a HiPIMS coating suitable for cemented carbide with multiple grain sizes according to claim 1, characterized in that: In the S3 arc electron source assisted cleaning and activation step, the arc electron source main power current is 70A~100A, the arc electron source auxiliary anode current is 30A~40A, the bias voltage is 100V~300V, the bias duty cycle is 50%~80%, and the cleaning time is 15~20min.

5. The method for preparing a HiPIMS coating suitable for cemented carbide with multiple grain sizes according to claim 1, characterized in that: In the S4 metal nitride coating deposition step, the target material includes one or more of a TiAl target and a TiSi target.

6. The method for preparing a HiPIMS coating adapted to cemented carbide with multiple grain sizes according to claim 1, characterized in that: In step S4, the working gases are N2 and Ar, the flow ratio of N2 to Ar is (0.3-0.8:1), the total flow range of the working gases is 200-300 SCCM, and the pressure in the cavity is maintained at 0.5 Pa.

7. The method for preparing a HiPIMS coating adapted to cemented carbide with multiple grain sizes according to claim 1, characterized in that: The thickness of the metal nitride coating of the prepared workpiece sample is 700-800 nm, the hardness of the metal nitride coating is ≥30 GPa, and the adhesion of the metal nitride coating is ≥120 N.

8. A hardware alloy cutting tool, characterized in that: The HiPIMS coating is prepared by the method for preparing a multi-grain-size cemented carbide according to any one of claims 1 to 7.

9. The hardware alloy cutting tool according to claim 8, characterized in that: The hardware alloy cutting tool comprises a cemented carbide substrate, on which a metal nitride coating is plated; The cemented carbide substrate is WC-Co cemented carbide, wherein the Co content is 10% and the WC grain size is 0.3 to 1.5 μm; The metal nitride coating is a nitride layer of one or more of Ti, Al, Si, Ta, Cr, Zr, and C.

10. The hardware alloy cutting tool according to claim 9, characterized in that: The metal nitride coating is a TiAlN coating with a thickness of 700-800 nm. The TiAlN coating comprises 18-22% Ti, 28-34% Al and 44-50% N in atomic percentage.

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