Titanium alloy cutting hard coating and method for manufacturing the same

Abstract

The application discloses a hard coating for titanium alloy cutting, characterized in that the hard coating comprises a bottom layer, an intermediate layer and a top layer; the bottom layer adopts a single-layer coating structure and is made of pure titanium carbide or molybdenum nitride to provide a simple and uniform tool surface coating; the intermediate layer adopts a multi-layer coating structure, an intermediate layer is introduced between the bottom layer and the top layer, and the material is titanium carbide or titanium nitride to build a composite geometric shape or combined structure; the top layer adopts a gradient coating structure, and the material is a titanium nitride-tungsten carbide composite coating, and the composition or property of the top layer gradually changes along the thickness direction. The hard coating for titanium alloy cutting provided by the application has excellent cutting performance, improved coating adhesion strength, improved structure and thickness distribution and other beneficial effects, and has a wide application prospect in the field of titanium alloy machining, has technical innovation and competitive advantage, and can promote the development of the titanium alloy manufacturing field.

Description

Technical Field

[0001] This invention relates to the technical field, specifically to a hard coating for titanium alloy cutting and its preparation method. Background Technology

[0002] In the field of titanium alloy machining, titanium alloy cutting tools are widely used in advanced manufacturing sectors such as aerospace and automotive. While titanium alloys possess high strength, low density, and good corrosion resistance, they also exhibit high hardness and difficulty in machining. This leads to titanium alloy cutting tools being prone to wear, high temperatures, and vibrations during the cutting process, ultimately affecting cutting quality and tool life.

[0003] To overcome the machinability of titanium alloys and improve the performance of titanium alloy cutting tools, a common method is to coat the tool surface with a hard coating. This hard coating can effectively reduce friction and wear between the tool and the workpiece during cutting, thereby increasing cutting speed and tool life.

[0004] However, existing coating technologies still have some limitations. First, some coating preparation methods require high temperatures and pressures, which may cause tool deformation or weak adhesion between the substrate and the coating. Second, the impact of the selection and mixing ratio of coating materials on the final coating performance is still unclear, and there is room for improvement in the coating's hardness, wear resistance, and cutting performance. Furthermore, the coating's structure and thickness distribution also need further optimization to improve its overall performance. Summary of the Invention

[0005] To address the aforementioned issues, this patent provides a method for preparing a hard coating for titanium alloy cutting. This method employs a specific coating preparation process, including bottom layer preparation, intermediate layer preparation, top layer preparation, transition region treatment, and structural improvement. Through this preparation method, a hard coating with a uniform structure, high adhesion strength, and excellent performance can be obtained, thereby improving the cutting performance, wear resistance, and lifespan of titanium alloy cutting tools.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a hard coating for cutting titanium alloys, comprising: the hard coating includes a bottom layer, an intermediate layer, and a top layer;

[0007] The bottom layer adopts a single-layer coating structure, and the material is pure titanium carbide or molybdenum nitride to provide a simple and uniform coating on the tool surface, with high hardness and wear resistance.

[0008] The intermediate layer adopts a multi-layer coating structure, introducing an intermediate layer between the bottom and top layers. The material is titanium carbide or titanium nitride to construct a composite geometry or combination structure, giving the tool complex wear resistance and cutting performance.

[0009] The top layer adopts a gradient coating structure, and the material is a titanium nitride-tungsten carbide composite coating. The composition or properties of the top layer gradually change along the thickness direction to achieve a gradual transition in performance.

[0010] Preferably, the thickness of the bottom layer is in the range of 0.3 to 0.6 μm, the thickness of the intermediate layer is in the range of 0.3 to 0.5 μm, and the thickness of the top layer gradually varies in the range of 1.5 to 2.0 μm.

[0011] Preferably, in the transition region from the intermediate layer to the top layer, the transition from high adhesion to high hardness is achieved by gradually adjusting the carbon content, nitrogen content, or the percentage of added titanium or tungsten elements, thereby reducing stress concentration between the coating and the substrate and improving the toughness and durability of the overall coating system.

[0012] A method for preparing a hard coating for cutting titanium alloys, characterized by comprising the following steps:

[0013] Step 1: Substrate preparation:

[0014] A1. Prepare pure titanium carbide or molybdenum nitride powder as raw material;

[0015] B1. A uniform coating of 0.3–0.6 μm thickness is formed on the surface of titanium alloy cutting tools using physical vapor deposition or chemical vapor deposition;

[0016] Step 2: Preparation of the intermediate layer:

[0017] A2. Prepare titanium carbide or titanium nitride powder, as well as powdered raw materials of other elements;

[0018] B2. Through multiple processes, using physical vapor deposition, chemical vapor deposition, or thermal spraying, the intermediate layer material is uniformly deposited on the bottom layer to form a composite coating structure of 0.3–0.5 μm.

[0019] Step 3: Top Layer Preparation

[0020] A3. Prepare the raw material powder for the titanium nitride-tungsten carbide composite coating;

[0021] B3. Using a gradual variation method, a titanium nitride-tungsten carbide composite coating is gradually deposited using physical vapor deposition and chemical vapor deposition coating processes to form a gradient structure that gradually varies within the range of 1.5 to 2.0 μm;

[0022] Step 4: Transition Area Processing

[0023] A4. For the transition area from the middle layer to the top layer, it is necessary to adjust the carbon content, nitrogen content, or add the percentage of titanium or tungsten elements. The transition from higher adhesion to higher hardness can be achieved by controlling the mixing atmosphere and deposition rate.

[0024] Step 5: Structural Improvement

[0025] A5. Post-treatment of the obtained coating, including annealing and surface treatment, to improve the bonding strength between the coating and the substrate and the overall performance.

[0026] Preferably, in step one, the underlying layer is prepared as follows:

[0027] The particle size of titanium carbide powder is between 1 and 10 micrometers, and the particle size of molybdenum nitride powder should be between 0.1 and 10 micrometers.

[0028] For physical vapor deposition:

[0029] The vacuum level is controlled within the range of 10^-3 to 10^-6 Pa to ensure a suitable working atmosphere;

[0030] The substrate temperature is set to 200-400℃ to promote the adhesion and growth of the coating material;

[0031] The film formation rate is controlled at 0.1-1 micrometer / minute to ensure the uniformity and density of the coating.

[0032] For chemical vapor deposition:

[0033] The temperature of the chemical reaction chamber is set at 800-1000℃ to activate the reaction of the raw material gases;

[0034] The coating growth rate is 0.5-2 micrometers / minute and needs to be adjusted according to requirements.

[0035] Preferably, step two, preparation of the intermediate layer:

[0036] The particle size range of titanium carbide powder and titanium nitride powder is selected to be 1-10 micrometers;

[0037] For physical vapor deposition and chemical vapor deposition:

[0038] The vacuum level is set to 10^-3 to 10^-6 Pa to ensure a suitable working atmosphere;

[0039] Determine the substrate temperature to be between 200-400°C to promote the adhesion and growth of the coating material;

[0040] Control the film formation rate to a range of 0.1-1 μm / min to ensure coating uniformity;

[0041] For thermal spraying:

[0042] The nozzle temperature is set at 2000-3000℃, depending on the material.

[0043] Control the gas flow rate to 30-50 sccm, adjusting according to specific nozzle parameters and powder characteristics;

[0044] Adjust the spraying distance to between 40-60mm to achieve uniform coating deposition.

[0045] Preferably, in step three, the top layer is prepared:

[0046] The particle size range of titanium nitride and tungsten carbide powders is selected to be 1-10 micrometers;

[0047] For physical vapor deposition and chemical vapor deposition:

[0048] The vacuum level is set to 10^-3 to 10^-6 Pa to ensure a suitable working atmosphere;

[0049] Determine the substrate temperature to be between 200-400°C to promote the adhesion and growth of the coating material.

[0050] Control the film formation rate to a range of 0.1-1 μm / min to ensure coating uniformity.

[0051] Preferably, in step four, the transition region is processed:

[0052] Adjust the percentage settings for carbon content, nitrogen content, or added titanium and tungsten elements:

[0053] For changing carbon content: gradually reduce carbon source flow rate, and in the transition region, gradually reduce the carbon source flow rate from the initial value of 30 sccm to 10 sccm;

[0054] To change the nitrogen content: gradually increase the nitrogen flow rate, and in the transition region, gradually increase the nitrogen flow rate from the initial value of 40 sccm to 70 sccm;

[0055] For the addition of titanium or tungsten: gradually increase the flow rate of the corresponding element, and adjust the flow rate ratio of the titanium or tungsten source to achieve the expected content change;

[0056] Set the initial flow rate of the titanium or tungsten source to 50 sccm;

[0057] Within the transition region, gradually increase the flow rate of the titanium or tungsten source by 5 sccm every 10 minutes until the desired content change is achieved.

[0058] Controlling the mixing atmosphere in the transition region:

[0059] Adjust the flow rate and pressure of the mixed gas to control the changes in the content of the desired elements;

[0060] Set the initial flow rate and pressure of the mixed gas to meet the requirements of the intermediate and top layers;

[0061] Within the transition zone, the flow rate and pressure of the mixed gas are gradually adjusted, with the flow rate of the mixed gas increased by 5 sccm every 10 minutes to control the changes in the content of the required elements.

[0062] Gradually adjust the deposition rate:

[0063] As the transition zone progresses, the deposition rate is gradually increased from 0.1 μm / min to 0.5 μm / min.

[0064] The present invention provides a hard coating for titanium alloy cutting and its preparation method, which has the following advantages:

[0065] 1. Improved cutting performance: By adopting a specific coating preparation process, the coating can effectively reduce friction and wear between titanium alloy tools and workpieces, improve cutting speed and tool life. The tool coating prepared by this method has excellent wear resistance, can significantly reduce cutting force and machining temperature, and improve cutting surface quality.

[0066] 2. Improved Coating Adhesion Strength: By optimizing the preparation of the substrate, treatment of the transition region, and structural improvement, the bonding strength between the coating and the substrate is enhanced, reducing the risk of coating peeling and failure. Experimental data show that the bonding strength between the coating and the substrate after annealing and surface treatment reaches an ideal level, capable of withstanding high cutting forces and vibrations.

[0067] 3. Improved Coating Structure and Thickness Distribution: By adjusting parameters such as the coating's constituent materials, carbon content, nitrogen content, and the addition of other elements, and employing a gradient structure design, the coating's thickness and structural distribution were optimized. Experimental data show that the gradually changing gradient structure formed between the top and intermediate layers provides better interface matching and stress distribution, further enhancing the overall performance of the coating.

[0068] In summary, the method for preparing hard coatings for titanium alloy cutting provided by this invention has beneficial effects such as excellent cutting performance, improved coating adhesion strength, and improved structure and thickness distribution. This method has broad application prospects in the field of titanium alloy processing, possesses technological innovation and competitive advantages, and can promote the development of the titanium alloy manufacturing field. Detailed Implementation

[0069] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0070] Example 1: This invention provides a technical solution: a hard coating for titanium alloy cutting, comprising:

[0071] Bottom layer: Made of pure titanium carbide with a thickness of 0.5μm, providing a uniform coating on the tool surface with high hardness and wear resistance;

[0072] Intermediate layer: Made of titanium carbide with a thickness of 0.4μm, it constructs a composite geometry or combination structure to provide complex wear resistance and machinability;

[0073] Top layer: A titanium nitride-tungsten carbide composite coating is used, with the thickness gradually varying in the range of 1.8 to 2.0 μm to achieve a gradual transition in performance changes.

[0074] A method for preparing a hard coating for cutting titanium alloys includes the following steps:

[0075] Step 1: Substrate preparation:

[0076] A1. Prepare pure titanium carbide or molybdenum nitride powder as raw material;

[0077] B1. A uniform coating of 0.5 μm thickness is formed on the surface of titanium alloy cutting tools using physical vapor deposition or chemical vapor deposition.

[0078] Substrate preparation:

[0079] The particle size of titanium carbide powder is 1 micrometer, and the particle size of molybdenum nitride powder is 0.1 micrometer.

[0080] For physical vapor deposition:

[0081] The vacuum level is controlled within the range of 10^-3 Pa to ensure a suitable working atmosphere;

[0082] The substrate temperature is set to 200°C to promote the adhesion and growth of the coating material;

[0083] The film formation rate was controlled at 0.1 micrometers / minute to ensure the uniformity and density of the coating.

[0084] For chemical vapor deposition:

[0085] The temperature of the chemical reaction chamber was set at 800℃ to activate the reaction of the raw material gases;

[0086] The coating growth rate is 0.5 micrometers per minute and needs to be adjusted according to requirements.

[0087] Step 2: Preparation of the intermediate layer:

[0088] A2. Prepare titanium carbide or titanium nitride powder, as well as powdered raw materials of other elements;

[0089] B2. Through multiple processes, using physical vapor deposition, chemical vapor deposition or thermal spraying, the intermediate layer material is uniformly deposited on the bottom layer to form a 0.4μm composite coating structure;

[0090] Step 2: Preparation of the intermediate layer:

[0091] The particle size range of titanium carbide powder and titanium nitride powder is selected to be 1-10 micrometers;

[0092] For physical vapor deposition and chemical vapor deposition:

[0093] The vacuum level is set to 10^-3 Pa to ensure a suitable working atmosphere;

[0094] The substrate temperature was determined to be within 200°C to promote the adhesion and growth of the coating material;

[0095] The film formation rate was controlled and determined to be within the range of 0.1 μm / min to ensure the uniformity of the coating.

[0096] For thermal spraying:

[0097] The nozzle temperature is set at 2000℃, but may vary depending on the material.

[0098] Control the gas flow rate to 30 sccm, and adjust it according to the specific nozzle parameters and powder characteristics;

[0099] Adjust the spraying distance to 40mm to achieve uniform coating deposition.

[0100] Step 3: Top Layer Preparation

[0101] A3. Prepare the raw material powder for the titanium nitride-tungsten carbide composite coating;

[0102] B3. Using a gradual variation method, a titanium nitride-tungsten carbide composite coating is gradually deposited using physical vapor deposition and chemical vapor deposition coating processes to form a gradient structure that varies gradually within the range of 1.8 to 2.0 μm.

[0103] Top layer preparation:

[0104] The particle size of the titanium nitride and tungsten carbide powders was selected to be 1 micrometer;

[0105] For physical vapor deposition and chemical vapor deposition:

[0106] The vacuum level is set to 10^-3 Pa to ensure a suitable working atmosphere;

[0107] The substrate temperature was determined to be within 200°C to promote the adhesion and growth of the coating material;

[0108] The film formation rate was controlled and determined to be within the range of 0.1 μm / min to ensure the uniformity of the coating.

[0109] Step 4: Transition Area Processing

[0110] A4. For the transition area from the middle layer to the top layer, it is necessary to adjust the carbon content, nitrogen content, or add the percentage of titanium or tungsten elements. The transition from higher adhesion to higher hardness can be achieved by controlling the mixing atmosphere and deposition rate.

[0111] Transition region processing:

[0112] Adjust the percentage settings for carbon content, nitrogen content, or added titanium and tungsten elements:

[0113] For changing carbon content: gradually reduce carbon source flow rate, and in the transition region, gradually reduce the carbon source flow rate from the initial value of 30 sccm to 10 sccm;

[0114] To change the nitrogen content: gradually increase the nitrogen flow rate, and in the transition region, gradually increase the nitrogen flow rate from the initial value of 40 sccm to 70 sccm;

[0115] For the addition of titanium or tungsten: gradually increase the flow rate of the corresponding element, and adjust the flow rate ratio of the titanium or tungsten source to achieve the expected content change;

[0116] Set the initial flow rate of the titanium or tungsten source to 50 sccm;

[0117] Within the transition region, gradually increase the flow rate of the titanium or tungsten source by 5 sccm every 10 minutes until the desired content change is achieved.

[0118] Controlling the mixing atmosphere in the transition region:

[0119] Adjust the flow rate and pressure of the mixed gas to control the changes in the content of the desired elements;

[0120] Set the initial flow rate and pressure of the mixed gas to meet the requirements of the intermediate and top layers;

[0121] Within the transition zone, the flow rate and pressure of the mixed gas are gradually adjusted, with the flow rate of the mixed gas increased by 5 sccm every 10 minutes to control the changes in the content of the required elements.

[0122] Gradually adjust the deposition rate:

[0123] As the transition zone progresses, the deposition rate is gradually increased from 0.1 μm / min to 0.5 μm / min.

[0124] Step 5: Structural Improvement

[0125] A5. Post-treatment of the obtained coating, including annealing and surface treatment, to improve the bonding strength between the coating and the substrate and the overall performance.

[0126] Example 2: A hard coating for cutting titanium alloys, comprising:

[0127] Bottom layer: Made of pure titanium carbide with a thickness of 0.6μm, providing a simple and uniform coating for the tool surface with high hardness and wear resistance.

[0128] Intermediate layer: Made of titanium carbide and titanium nitride, with a thickness of 0.5μm, it constructs a composite geometry or combination structure to provide complex wear resistance and machinability.

[0129] Top layer: A titanium nitride-tungsten carbide composite coating is used, with the thickness gradually varying in the range of 1.5 to 1.8 μm to achieve a gradual transition in performance changes.

[0130] A method for preparing a hard coating for cutting titanium alloys includes the following steps:

[0131] Step 1: Substrate preparation:

[0132] A1. Prepare pure titanium carbide or molybdenum nitride powder as raw material;

[0133] B1. A uniform coating of 0.6 μm thickness is formed on the surface of titanium alloy cutting tools using physical vapor deposition or chemical vapor deposition.

[0134] Substrate preparation:

[0135] The particle size of titanium carbide powder is between 10 micrometers, and the particle size of molybdenum nitride powder should be between 10 micrometers.

[0136] For physical vapor deposition:

[0137] The vacuum level is controlled within the range of 10^-6 Pa to ensure a suitable working atmosphere;

[0138] The substrate temperature was set to 400°C to promote the adhesion and growth of the coating material;

[0139] The film formation rate is controlled at 1 micrometer / minute to ensure the uniformity and density of the coating;

[0140] For chemical vapor deposition:

[0141] The temperature of the chemical reaction chamber was set at 1000℃ to activate the reaction of the raw material gases;

[0142] The coating growth rate is 2 micrometers per minute and needs to be adjusted according to requirements.

[0143] Step 2: Preparation of the intermediate layer:

[0144] A2. Prepare titanium carbide or titanium nitride powder, as well as powdered raw materials of other elements;

[0145] B2. Through multiple processes, using physical vapor deposition, chemical vapor deposition or thermal spraying, the intermediate layer material is uniformly deposited on the bottom layer to form a 0.5μm composite coating structure.

[0146] Intermediate layer preparation:

[0147] The particle size range of titanium carbide powder and titanium nitride powder is selected to be 10 micrometers;

[0148] For physical vapor deposition and chemical vapor deposition:

[0149] The vacuum level is set to 10^-6 Pa to ensure a suitable working atmosphere;

[0150] The substrate temperature was determined to be within 400°C to promote the adhesion and growth of the coating material;

[0151] The film formation rate was controlled and kept within the range of 1 μm / min to ensure the uniformity of the coating.

[0152] For thermal spraying:

[0153] The nozzle temperature is set at 3000℃, but this may vary depending on the material.

[0154] Control the gas flow rate to 50 sccm, and adjust it according to the specific nozzle parameters and powder characteristics;

[0155] Adjust the spraying distance to 60mm to achieve uniform coating deposition.

[0156] Step 3: Top Layer Preparation

[0157] A3. Prepare the raw material powder for the titanium nitride-tungsten carbide composite coating;

[0158] B3. Using a gradual variation method, a titanium nitride-tungsten carbide composite coating is gradually deposited using physical vapor deposition and chemical vapor deposition coating processes to form a gradient structure that gradually varies within the range of 1.5 to 2.0 μm;

[0159] Step 4: Transition Area Processing

[0160] A4. For the transition area from the middle layer to the top layer, it is necessary to adjust the carbon content, nitrogen content, or add the percentage of titanium or tungsten elements. The transition from higher adhesion to higher hardness can be achieved by controlling the mixing atmosphere and deposition rate.

[0161] Step 5: Structural Improvement

[0162] A5. Post-treatment of the obtained coating, including annealing and surface treatment, to improve the bonding strength between the coating and the substrate and the overall performance.

[0163] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A hard coating for cutting titanium alloys, characterized in that, include: The hard coating comprises a base layer, an intermediate layer, and a top layer; The bottom layer adopts a single-layer coating structure, and the material is pure titanium carbide or molybdenum nitride to provide a simple and uniform coating on the tool surface, with high hardness and wear resistance. The intermediate layer adopts a multi-layer coating structure, introducing an intermediate layer between the bottom and top layers. The material is titanium carbide or titanium nitride to construct a composite geometry or combination structure, giving the tool complex wear resistance and cutting performance. The top layer adopts a gradient coating structure, and the material is a titanium nitride-tungsten carbide composite coating. The composition or properties of the top layer gradually change along the thickness direction to achieve a gradual transition in performance. In the transition region from the intermediate layer to the top layer, the transition from high adhesion to high hardness is achieved by gradually adjusting the carbon content, nitrogen content, or the percentage of added titanium or tungsten elements. This reduces stress concentration between the coating and the substrate, and improves the toughness and durability of the overall coating system.

2. The hard coating for titanium alloy cutting according to claim 1, characterized in that: The thickness of the bottom layer is in the range of 0.3 to 0.6 μm, the thickness of the middle layer is in the range of 0.3 to 0.5 μm, and the thickness of the top layer gradually varies in the range of 1.5 to 2.0 μm.

3. The method for preparing a hard coating for titanium alloy cutting according to claim 2, characterized in that: Includes the following steps: Step 1: Substrate preparation: A1. Prepare pure titanium carbide or molybdenum nitride powder as raw material; B1. A uniform coating of 0.3–0.6 μm thickness is formed on the surface of titanium alloy cutting tools using physical vapor deposition or chemical vapor deposition; Step 2: Preparation of the intermediate layer: A2. Prepare titanium carbide or titanium nitride powder, as well as powdered raw materials of other elements; B2. Through multiple processes, using physical vapor deposition, chemical vapor deposition or thermal spraying, the intermediate layer material is uniformly deposited on the bottom layer to form a composite coating structure of 0.3~0.5 μm; Step 3: Top Layer Preparation A3. Prepare the raw material powder for the titanium nitride-tungsten carbide composite coating; B3. Using a gradual variation method, a titanium nitride-tungsten carbide composite coating is gradually deposited using physical vapor deposition and chemical vapor deposition coating processes to form a gradient structure that gradually varies within the range of 1.5 to 2.0 μm; Step 4: Transition Area Processing A4. For the transition area from the middle layer to the top layer, it is necessary to adjust the carbon content, nitrogen content, or add the percentage of titanium or tungsten elements. The transition from higher adhesion to higher hardness can be achieved by controlling the mixing atmosphere and deposition rate. Step 5: Structural Improvement A5. Post-treatment of the obtained coating, including annealing and surface treatment, to improve the bonding strength between the coating and the substrate and the overall performance.

4. The method for preparing a hard coating for titanium alloy cutting according to claim 3, characterized in that: In step one, the underlying layer is prepared as follows: The particle size of titanium carbide powder is between 1 and 10 micrometers, and the particle size of molybdenum nitride powder should be between 0.1 and 10 micrometers. For physical vapor deposition: The vacuum level is controlled within the range of 10^-3 to 10^-6 Pa to ensure a suitable working atmosphere; The substrate temperature is set to 200-400℃ to promote the adhesion and growth of the coating material; The film formation rate is controlled at 0.1-1 micrometer / minute to ensure the uniformity and density of the coating. For chemical vapor deposition: The temperature of the chemical reaction chamber is set at 800-1000℃ to activate the reaction of the raw material gases; The coating growth rate is 0.5-2 micrometers / minute and needs to be adjusted according to requirements.

5. The method for preparing a hard coating for titanium alloy cutting according to claim 4, characterized in that: Step 2: Preparation of the intermediate layer: The particle size range of titanium carbide powder and titanium nitride powder is selected to be 1-10 micrometers; For physical vapor deposition and chemical vapor deposition: The vacuum level is set to 10^-3 ~ 10^-6 Pa to ensure a suitable working atmosphere; Determine the substrate temperature to be between 200-400°C to promote the adhesion and growth of the coating material; Control the film formation rate to a range of 0.1-1 μm / min to ensure coating uniformity; For thermal spraying: The nozzle temperature is set at 2000-3000℃, depending on the material. Control the gas flow rate to 30-50 sccm, adjusting according to specific nozzle parameters and powder characteristics; Adjust the spraying distance to between 40-60 mm to achieve uniform coating deposition.

6. The method for preparing a hard coating for titanium alloy cutting according to claim 5, characterized in that: In step three, the top layer is prepared: The particle size range of titanium nitride and tungsten carbide powders is selected to be 1-10 micrometers; For physical vapor deposition and chemical vapor deposition: The vacuum level is set to 10^-3~10^-6 Pa to ensure a suitable working atmosphere; Determine the substrate temperature to be between 200-400°C to promote the adhesion and growth of the coating material; Control the film formation rate to a range of 0.1-1 μm / min to ensure coating uniformity.

7. The method for preparing a hard coating for titanium alloy cutting according to claim 6, characterized in that: Step four involves processing the transition region: Adjust the percentage settings for carbon content, nitrogen content, or added titanium and tungsten elements: For changing carbon content: gradually reduce carbon source flow rate, and gradually reduce carbon source flow rate from the initial value of 30 sccm to 10 sccm in the transition region; To change the nitrogen content: gradually increase the nitrogen flow rate, and gradually increase the nitrogen flow rate from the initial value of 40 sccm to 70 sccm in the transition region; For the addition of titanium or tungsten: gradually increase the flow rate of the corresponding element, and adjust the flow rate ratio of the titanium or tungsten source to achieve the expected content change; Set the initial flow rate of the titanium or tungsten source to 50 sccm; Within the transition region, gradually increase the flow rate of the titanium or tungsten source by 5 sccm every 10 minutes until the desired content change is achieved. Controlling the mixing atmosphere in the transition region: Adjust the flow rate and pressure of the mixed gas to control the changes in the content of the desired elements; Set the initial flow rate and pressure of the mixed gas to meet the requirements of the intermediate and top layers; Within the transition zone, the flow rate and pressure of the mixed gas are gradually adjusted, with the flow rate of the mixed gas increased by 5 sccm every 10 minutes to control the changes in the content of the required elements. Gradually adjust the deposition rate: As the transition zone progresses, the deposition rate is gradually increased from 0.1 μm / min to 0.5 μm / min.