Preparation method of self-hardening PVD film

Abstract

The invention provides a preparation method of a self-hardening PVD (Physical Vapor Deposition) film. The method comprises the following steps: S1, pretreating a substrate in multi-arc ion plating equipment; s2, nitrogen is introduced into the multi-arc ion plating equipment, preset pressure is kept in the multi-arc ion plating equipment, an electric arc TiAl target is started, and a TiAlN transition layer with the preset thickness is deposited on the surface of the pretreated base body; s3, mixed gas of nitrogen and carbon source gas with the preset mass flow ratio is introduced, the total flow of the mixed gas is kept unchanged, a TiAlCN film with the preset thickness is deposited on the TiAlN transition layer, and surface liquid drop proportion control is conducted on the TiAlCN film; s4, carrying out detection analysis on the TiAlCN thin film; and S5, the TiAlCN thin film meeting the requirement is subjected to aftertreatment. The preparation method of the self-hardening PVD film provided by the invention at least can solve the problem of poor self-hardening effect of the film prepared by the preparation method of the PVD film in the prior art.

Description

Technical Field

[0001] The present invention relates to thin film preparation technology, and more particularly, to a method for preparing a self-hardening PVD thin film. Background Art

[0002] A self-hardening PVD thin film refers to a thin film material with self-hardening characteristics prepared by physical vapor deposition (PVD, Physical Vapor Deposition) technology, that is, during or after deposition, without additional heat treatment or chemical treatment, the thin film itself realizes hardness improvement through structural evolution, stress accumulation or composition reaction.

[0003] Currently, in the field of traditional PVD thin films, the hardness of the thin film is mainly improved by increasing the hardness and toughness of the thin film, adjusting the interlayer structure or doping heterogeneous elements, etc. However, the self-hardening effect of the thin film prepared by the foregoing method is not significant or the thin film does not have a self-hardening effect, resulting in a decrease in the mechanical properties of the thin film, weakening of the binding force between the base film and heat, causing peeling and flaking of the thin film, and affecting the service life of tools or components. Summary of the Invention

[0004] The main object of the present invention is to provide a method for preparing a self-hardening PVD thin film to solve the problem of poor self-hardening effect of the thin film prepared by the existing method for preparing a PVD thin film.

[0005] To achieve the above object, according to one aspect of the present invention, there is provided a method for preparing a self-hardening PVD thin film, including:

[0006] Step S1: Pretreating the substrate in a multi-arc ion plating equipment;

[0007] Step S2: Introducing nitrogen into the multi-arc ion plating equipment and maintaining a predetermined pressure in the multi-arc ion plating equipment, and turning on the arc TiAl target to deposit a TiAlN transition layer with a predetermined thickness on the surface of the pretreated substrate;

[0008] Step S3: Introducing a mixed gas of nitrogen and a carbon source gas with a predetermined mass flow ratio and keeping the total flow rate of the mixed gas unchanged to deposit a TiAlCN thin film with a predetermined thickness on the TiAlN transition layer and controlling the surface droplet ratio of the TiAlCN thin film;

[0009] Step S4: Detecting and analyzing the TiAlCN thin film;

[0010] Step S5: Post-treating the TiAlCN thin film that meets the requirements.

[0011] Further, in the step S3, the mass flow ratio of the nitrogen gas to the carbon source gas is 10:1 - 100:1.

[0012] Further, in the step S3, the carbon source gas includes acetylene.

[0013] Further, in the step S3, the nitrogen gas leads to the surface of the arc cathode inside the multi-arc ion plating equipment through a gas pipe; and / or,

[0014] The acetylene is introduced into the multi-arc ion plating equipment through a gas pipe on the furnace wall of the multi-arc ion plating equipment.

[0015] Further, the hardness of the TiAlCN thin film in the step S3 is 30 GPa - 38 GPa.

[0016] Further, in the step S4, the detection and analysis include measuring the atomic ratio of the C element, the atomic ratio of the C element + N element, and the surface droplet ratio in the TiAlCN thin film.

[0017] Further, in the step S5, the atomic ratio of the C element in the qualified TiAlCN thin film is 5 at% - 20 at%; and / or,

[0018] The atomic ratio of the C element + N element in the qualified TiAlCN thin film is 40 at% - 60 at%; and / or,

[0019] The surface droplet ratio of the qualified TiAlCN thin film is less than or equal to 2.0%.

[0020] Further, in the step S5, the post-treatment method includes polishing or stamping.

[0021] Further, the thickness of the TiAlN transition layer is 0.2 μm - 2.0 μm; and / or,

[0022] The thickness of the TiAlCN thin film is 1.0 μm - 10 μm.

[0023] Further, the process temperature in the preparation method of the self-hardening PVD thin film is 400 °C - 600 °C.

[0024] Applying the technical solution of the present invention, a preparation method of a self-hardening PVD thin film is provided. By reasonably designing the gas flow rate, bias voltage parameters, and target combination, a TiAlCN thin film with low defects and high hardness is successfully prepared. Moreover, the work hardening phenomenon of this thin film is remarkable, indicating that the coating has excellent surface strengthening potential. Combining its composition and structural advantages, it has broad application prospects in the fields of high-end cutting tools, wear-resistant molds, and aerospace.

[0025] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The present invention will be further described in detail below with reference to the drawings. Description of the Drawings

[0026] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0027] Figure 1 A flowchart showing a method for preparing a self-hardening PVD film disclosed according to an embodiment of the present invention is shown. Detailed Embodiments

[0028] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0029] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so as to describe the embodiments of the present invention here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] As mentioned in the background art, currently, in the field of traditional PVD thin films, the hardness of thin films is mainly improved by increasing the hardness and toughness of the thin films, adjusting the interlayer structure, or doping heterogeneous elements, etc. However, the self-hardening effect of the thin films prepared by the aforementioned methods is not significant or the thin films do not have a self-hardening effect, resulting in a decline in the mechanical properties of the thin films, a weakening of the binding force between the base films, heat causing the thin films to peel off, flake, and affecting the service life of tools or components to decrease. Therefore, the present application provides a method for preparing a self-hardening PVD thin film, and this method for preparing a self-hardening PVD thin film can solve the problem of poor self-hardening effect of the thin films prepared by the existing methods for preparing PVD thin films.

[0033] As Figure 1 shown, according to an embodiment of the present application, a method for preparing a self-hardening PVD thin film is provided.

[0034] Among them, the PVD thin film is formed by physically evaporating and ionizing a metal or other coating material in a vacuum environment and then depositing it on the surface of a substrate. The self-hardening principle of the self-hardening PVD thin film is usually related to the composition and microstructure of the thin film material. For example, some thin films containing elements such as carbon and nitrogen will undergo changes in atomic arrangement or chemical reactions during the deposition process or in the subsequent use environment, causing their hardness to gradually increase over time or under specific conditions. Taking the diamond-like carbon (DLC) thin film as an example, it contains carbon atoms with sp³ and sp² bonds. Under certain conditions, an increase in the proportion of sp³ bonds will increase the hardness of the thin film, showing a self-hardening effect.

[0035] Specifically, the method for preparing the self-hardening PVD thin film includes:

[0036] Step S1: Pretreat the substrate in a multi-arc ion plating equipment.

[0037] In the present application, the pretreatment includes first performing cutting, polishing, cleaning, and drying on the surface of the substrate. Among them, the cleaning method can be ultrasonic cleaning, chemical cleaning, and plasma cleaning. The drying method can be nitrogen blowing, centrifugal drying, etc. Exemplarily, in the present application, the substrate material can be alloy steel, high-speed steel, stainless steel, etc. In the present application, it is preferred that the substrate is a high-temperature tempered alloy steel with a hardness greater than or equal to 58HRC, and this alloy steel has high hardness. Then, place the dried substrate in the multi-arc ion plating equipment for ion etching to clean the surface of the substrate, which can further remove the adsorbed substances, oxide layers, and slightly contaminated layers on the surface of the substrate, thereby obtaining a clean surface at the atomic level. In addition, in the present application, the process temperature in the multi-arc ion plating equipment is in the range of 400°C - 600°C.

[0038] Furthermore, multi-arc ion plating belongs to a type of physical vapor deposition (PVD). Through arc discharge, the target material is evaporated and ionized, and the ions are deposited on the substrate surface under the action of an electric field to form a thin film.

[0039] Step S2: Introduce nitrogen gas into the multi-arc ion plating equipment and keep a predetermined pressure inside the multi-arc ion plating equipment. Turn on the arc TiAl target to deposit a TiAlN transition layer with a predetermined thickness on the surface of the pretreated substrate.

[0040] This step belongs to the underlayer deposition process of multi-arc ion plating and is a basic link for hard thin films. In this step, by depositing a TiAlN transition layer with a thickness of 0.2 μm - 2.0 μm on the pretreated substrate, the adhesion, hardness, and comprehensive performance of the subsequent TiAlCN thin film can be significantly improved. Precise control of the nitrogen pressure, optimization of the arc parameters and substrate bias voltage, and reasonable selection of the TiAl target composition are required in this step. Exemplarily, the thickness of the TiAlN transition layer can be 0.2 μm, 1.0 μm, 2.0 μm, etc., and the specific thickness depends on the final application requirements and is not specifically limited in this application.

[0041] Specifically, in this application, nitrogen gas with a pressure of 1 Pa - 8 Pa is introduced into the multi-arc ion plating equipment. Exemplarily, the nitrogen pressure can be 1 Pa, 3 Pa, 5 Pa, 8 Pa, etc. In this application, the preferred nitrogen pressure is 3 Pa - 8 Pa. When the nitrogen pressure is within this range, the densification of the TiAlN transition layer can be enhanced, the uniformity of the TiAlN transition layer can be improved, the adhesion between the TiAlN transition layer and the substrate can be improved, and the content of N element in the TiAlN transition layer can be controlled, thereby increasing the hardness of the TiAlN transition layer. In this application, the proportion of Al element in the TiAl target is 40 at% - 70 at%, and the proportion of N element in the TiAlN transition layer is 40% - 60 at%. Such settings are beneficial to ensuring the hardness of the TiAlCN thin film. At the same time, in this step, the pulsed bias voltage needs to be maintained between 0 V and 200 V, the target current needs to be maintained between 60 A and 120 A, and the reaction temperature needs to be maintained between 400 °C and 600 °C to promote the ion bombardment effect and further improve the densification and adhesion of the TiAlN transition layer.

[0042] That is to say, in this application, multi-arc ion plating is adopted, and a TiAlN transition layer is set between the substrate and the subsequently deposited TiAlCN thin film, which can enhance the bonding force between the TiAlCN thin film and the substrate, improve the surface morphology and uniformity of the substrate, and avoid affecting the hardness of the thin film due to fluctuations in the thin film thickness caused by surface non-uniformity.

[0043] Step S3: Introduce a mixed gas of nitrogen and a carbon source gas with a predetermined mass flow ratio, and keep the total flow rate of the mixed gas unchanged, so as to deposit a TiAlCN thin film with a predetermined thickness on the TiAlN transition layer, and control the surface droplet ratio of the TiAlCN thin film.

[0044] Specifically, the range of the mass flow ratio of nitrogen to the carbon source gas is 10:1 - 100:1. Exemplarily, the mass flow ratio of nitrogen to the carbon source gas can be 10:1, 50:1, 80:1, 100:1, etc. The specific ratio is determined according to the actual production process and is not specifically limited in this application. If the proportion of the carbon source gas is too high (i.e., carbon is in excess), it is easy to form amorphous carbon or graphite phase. Such structures have a layered arrangement, resulting in a decrease in the hardness of the TiAlCN thin film. If the proportion of nitrogen is too high, the carbon content in the formed TiAlCN thin film is insufficient, and it is difficult to produce an obvious self-hardening effect.

[0045] Furthermore, in this application, the carbon source gas is acetylene. In the preparation of physical vapor deposition (PVD) thin films, acetylene decomposes under the bombardment of high-energy particles (such as electrons, ions), releasing carbon-containing active groups (such as C⁺, CH X radicals), which react with metal elements (such as Ti, Cr, Ta) or other gases (such as H2, N2) to deposit a carbon-containing thin film, and this carbon-containing thin film has a high hardness.

[0046] Furthermore, in this application, nitrogen is led to the surface of the arc cathode in the multi-arc ion plating equipment through a gas pipe; acetylene is introduced into the multi-arc ion plating equipment through a gas pipe on the furnace wall of the multi-arc ion plating equipment. Among them, leading nitrogen directly to the surface of the arc cathode helps to form a protective atmosphere around the target. Introducing acetylene from the furnace wall can ensure the uniform distribution of the gas in the entire chamber and reduce the contamination of the cathode area and the target by carbon particles generated by the decomposition of acetylene, maintaining the purity of the process environment. In addition, in this application, directly applying nitrogen to the surface of the arc cathode can suppress the droplet ratio on the surface of the TiAlCN thin film, thereby improving the performance of the thin film. Of course, in other embodiments of this application, controlling the droplet ratio can also be used in the step of depositing the TiAlN transition layer to further improve the hardness and self-hardening effect of the thin film.

[0047] Further, in the present application, the thickness of the TiAlCN thin film is 1.0 μm - 10 μm. Exemplarily, the thickness of the TiAlCN thin film can be 1.0 μm, 2.0 μm, 5.0 μm, 10 μm, etc. When the thickness of the TiAlCN thin film is within the above range, the thin film can maintain a relatively high hardness. If the thin film is too thin (less than 1.0 μm), it may not be able to form a sufficiently continuous and uniform protective layer, resulting in uneven hardness distribution and difficulty in exerting its due wear-resistant performance. On the contrary, an overly thick thin film (exceeding 10 μm) may cause cracks or peeling of the thin film due to increased internal stress, thereby reducing the effective hardness. In addition, when the thickness of the thin film is within the range of 1.0 μm - 10 μm, the thin film can better maintain the integrity of its microstructure, such as grain size, phase composition, etc., which has a direct impact on hardness. And as the thickness of the thin film increases, the residual stress generated inside the thin film will also increase. That is to say, when the thickness of the thin film is within the range of 1.0 μm to 10 μm, these stresses can be controlled by optimizing process parameters to ensure that the thin film neither lacks a protective effect due to being too thin nor generates excessive internal stress due to being too thick, resulting in a decrease in hardness or thin film failure.

[0048] Further, in the step of preparing the TiAlCN thin film, it is necessary to control the droplet ratio on the surface of the TiAlCN thin film to improve the quality and performance of the TiAlCN thin film. If the droplet ratio on the surface of the TiAlCN thin film is too large, it will lead to a reduction or even disappearance of the self-hardening effect on the surface of the thin film. During the multi-arc ion plating process, the droplet ratio can be mainly controlled by adjusting the nitrogen partial pressure, increasing the arc spot rotation speed, and enhancing the cathode cooling capacity. Among them, in terms of using the nitrogen partial pressure, nitrogen can dilute the metal vapor concentration in the plasma environment, thereby reducing the probability of droplet formation. In addition, nitrogen can also participate in the reaction to form nitrides, which helps to improve the thin film structure and reduce droplet defects.

[0049] Further, in the present application, during the deposition process of the TiAlCN thin film, the substrate bias voltage is set within the range of 80 V - 200 V. Such a setting is beneficial to enhancing the ion bombardment effect, improving the crystallization quality, and controlling the internal stress, thereby improving the self-hardening effect of the thin film. In addition, when the substrate bias voltage is within the range of 80 V - 200 V, the hardness of the thin film generally shows an upward trend, mainly because the high-energy ion bombardment not only cleans the surface but also promotes the closer packing of thin film atoms, forming a more dense and hardened structure.

[0050] Step S4: Detect and analyze the TiAlCN thin film.

[0051] Specifically, in this application, the detection and analysis mainly include the determination of the atomic ratio of C element, the atomic ratio of C element + N element, and the surface droplet ratio in the TiAlCN thin film. Among them, the C content in the TiAlCN thin film directly affects the hardness of the TiAlCN thin film. By accurately measuring the ratio of C element, the expected physical properties of the thin film can be ensured. The determination of the atomic ratio of C element + N element is mainly because C element and N element jointly act on the mechanical properties and chemical properties of the thin film. By measuring the atomic ratio of C element + N element, the synergistic effect between the two can be better understood, and then the preparation of the thin film can be optimized. In addition, the determination of the surface droplet ratio helps to monitor the production quality of the thin film and ensure the smooth surface of the thin film to improve the hardness of the thin film.

[0052] Furthermore, the atomic ratio of C element in the TiAlCN thin film meeting the requirements is 5 at% - 20 at%. Exemplarily, the atomic ratio of C element in the TiAlCN thin film meeting the requirements can be 5 at%, 15 at%, 20 at%, etc., and no specific limitation is made in this application. When the C content is too low (<5 at%), insufficient carbide phases (such as TiC, AlC) cannot be formed, resulting in insufficient hardness of the thin film; when the C content is too high (>20 at%), amorphous carbon or graphite structure (sp² hybridization) is easily generated, reducing the hardness and affecting the denseness of the thin film.

[0053] Furthermore, the atomic ratio of C element + N element in the TiAlCN thin film meeting the requirements is 40 at% - 60 at%. Exemplarily, the atomic ratio of C element + N element in the TiAlCN thin film meeting the requirements can be 40 at%, 50 at%, 55 at%, 60 at%, etc., and no specific limitation is made to the numerical value in this application. In the Ti - Al - C - N system, high strength is mainly provided by hard phases such as TiC, TiN, Ti(C, N), and AlN. Controlling the atomic ratio of C element + N element within this range can ensure the full formation of these functional phases, thereby improving the hardness of the thin film.

[0054] Furthermore, the surface droplet ratio of the TiAlCN film meeting the requirements is less than or equal to 2.0%. Exemplarily, the droplet ratio can be 0.1%, 0.5%, 1.5%, 2.0%, etc., and specific numerical limitations are not imposed in this application. When the droplet ratio on the film surface ≤ 2.0%, the defect sources can be reduced, and the consistency of the film surface hardness can be improved. The presence of droplets may weaken the overall structure of the film because they may become the starting points of crack propagation or the weaker parts. By restricting the droplet ratio, it can be ensured that the film has higher overall hardness and maintains the self-hardening effect. Restricting the droplet ratio reduces the weak links, enabling the film to better resist external pressure and wear. In addition, a low droplet ratio helps to form a more uniform and dense microstructure, thereby increasing the hardness of the film. That is to say, controlling the droplet ratio at ≤ 2% can not only directly increase the hardness of the TiAlCN film, making it more uniform, but also enhance its self-hardening effect by improving the microstructure and surface quality of the film, ultimately achieving better mechanical properties and durability.

[0055] Furthermore, in this application, a nanoindentation hardness tester is used to measure the film hardness, and the hardness of the TiAlCN film is 30 GPa - 38 GPa. The hardness of the TiAlCN film deposited according to the above preparation method is measured to be in the range of 30 GPa - 38 GPa. Exemplarily, the hardness of the TiAlCN film can be 30 GPa, 32 GPa, 34 GPa, 36 GPa, 38 GPa, etc. That is to say, the TiAlCN film deposited by using the film preparation method provided in this application has a relatively high hardness.

[0056] Step S5: Post-treat the TiAlCN film meeting the requirements.

[0057] Furthermore, the post-treatment method can be polishing or stamping. In this application, polishing or stamping is performed on the TiAlCN film meeting the requirements to achieve work hardening, so as to further improve the hardness, wear resistance, and other mechanical properties of the film, and enhance its performance in specific applications. Through experimental verification, the hardness of the initially deposited TiAlCN film is 30 GPa - 38 GPa, and the hardness of the film can be increased by 5 GPa - 10 GPa on the original basis after post-treatment. Of course, in other embodiments of this application, ion implantation or shot peening can also be used to improve the work hardening effect of the TiAlCN film. Among them, ion implantation is to inject specific ions (such as nitrogen, carbon) into the surface layer of the film, which can effectively increase its hardness and wear resistance. Shot peening is to impact the film surface by high-speed spraying of small particles, causing plastic deformation and forming a layer of compressive stress zone, thereby increasing the surface hardness and fatigue strength. As long as it is other embodiments under the deformation of the concept of this application, they are all within the protection scope of this application.

[0058] Specifically, work hardening, also known as cold working hardening, refers to the phenomenon that during the plastic deformation process of metal materials at normal temperature or below the recrystallization temperature, as the amount of deformation increases, the strength and hardness of the material increase, while the plasticity and toughness decrease. The plastic deformation of metal materials is mainly achieved through the movement of dislocations inside the crystal. For metal materials that cannot be strengthened by heat treatment (such as pure metals, austenitic stainless steels, deformed aluminum alloys, etc.), work hardening is an important strengthening method.

[0059] The TiAlCN thin film prepared by this application can be widely used in the following fields due to its excellent hardness and wear resistance: Cutting tools: turning tools, milling cutters, drills, especially suitable for dry machining and high-speed cutting; Die manufacturing: injection molds, stamping dies, drawing dies, to extend the service life; Automotive parts: surface strengthening of components such as piston rings, camshafts, gears, etc.; Aerospace: wear protection of lightweight and high-strength parts; and Medical devices: surgical instruments, implants, etc. in occasions with high requirements for biocompatibility and wear resistance.

[0060] To verify the technical effects of this application, the following specific embodiments are provided in this application:

[0061] Example 1

[0062] First, polish the M2 high-speed steel test block to a surface roughness Ra < 0.1μm, clean it, and place it in a multi-arc ion plating equipment. Heat it to 500°C and clean the surface with argon ion etching.

[0063] Then, introduce 800 sccm of nitrogen, control the nitrogen pressure to 3 Pa, turn on the arc TiAl5050 target, with a cathode current of 100 A and a substrate bias voltage of 40 V, to deposit a TiAlN layer with a thickness of 0.5μm.

[0064] Next, set the nitrogen to 785 sccm to the surface of the target, and set the acetylene to 15 sccm to be introduced into the furnace through the furnace wall gas pipe. Keep the cathode current at 100 A and the substrate bias voltage at 120 V, and deposit a TiAlCN layer with a thickness of 2μm.

[0065] Detect and analyze the TiAlCN layer: The atomic ratio of C element is 6 at%, the atomic ratio of C element + N element is 51 at%, and the surface droplet area is 1.1%. Use a nano-indentation hardness tester to measure the hardness of the thin film. The nano-hardness is 32.5 GPa. After high-speed polishing of the thin film, measure the nano-hardness again, which is 41 GPa. After polishing, significant work hardening occurs in TiAlCN, and the nano-hardness increases by about 8.5 GPa.

[0066] Example 2

[0067] First, polish the SKD11 material test block and the stamping die to a surface roughness Ra < 0.1 μm. After cleaning, place them in a multi-arc ion plating equipment, heat to 500 °C, and clean the surface with argon ion etching.

[0068] Then introduce 1000 sccm of nitrogen, with a reaction pressure of 5 Pa. Turn on the arc TiAl4060 target, with a cathode current of 80 A and a substrate bias voltage of 60 V to deposit a TiAlN layer with a thickness of 1.2 μm.

[0069] Next, set the nitrogen to 750 sccm and lead it to the surface of the target, and set the acetylene to 50 sccm and introduce it into the furnace through the gas pipe on the furnace wall. Keep the cathode current at 80 A and the substrate bias voltage at 100 V to deposit a TiAlCN layer with a thickness of 3.5 μm.

[0070] Detect and analyze the TiAlCN layer: The atomic ratio of C element is 13%, the atomic ratio of C + N element is 52%, and the surface droplet area is 1.8%. Use a nano-indentation hardness tester to measure the hardness of the film. The nano-hardness is 35 GPa. After high-speed polishing the film on the sample block, re-measure the nano-hardness to be 44 GPa. After polishing, significant work hardening occurs in TiAlCN, and the nano-hardness increases by about 9 GPa. Install the stamping die on the stamping equipment to work normally. After processing 200 products, take it down and measure the hardness of the film on the die surface to be 41 GPa, and the hardness increases by 6 GPa, indicating that obvious work hardening occurs in the film at the initial stage of being subjected to pressure. After the hardness is increased, the wear resistance of the die can be effectively improved, and thus its service life can be extended, especially suitable for the processing field of ultra-high-strength plates.

[0071] In addition, after static treatment of the hardened TiAlCN films on the test blocks in Example 1 and Example 2 for 120 hours, re-measure the nano-hardness again. The measured hardnesses are 40.5 GPa and 43 GPa respectively. Although the hardness is slightly lower than that when it was just prepared, there is still a significant hardening effect compared to the initial state. That is to say, the TiAlCN film obtained by using the self-hardening PVD film preparation method provided by this application can significantly improve its hardness and work hardening effect. [[ID=**]]

[0072] From the above examples, it can be known that by using the self-hardening PVD film preparation method provided by this application, through reasonable design of gas flow rate, bias voltage parameters and target material combination, a TiAlCN film with low defects and high hardness is successfully prepared. And the work hardening phenomenon of this film is significant, indicating that the coating has excellent surface strengthening potential. Combining its composition and structural advantages, it has broad application prospects in the fields of high-end tools, wear-resistant dies and aerospace.

[0073] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific values should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, further discussion thereof is not required in subsequent drawings.

[0074] For the sake of convenience of description, spatial relative terms such as "above", "over", "on the upper surface", "upper" etc. may be used herein to describe the spatial positional relationship of one device or feature shown in the drawings with other devices or features. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the drawings. For example, if the device in the drawing is inverted, the device described as "above" or "over" other devices or structures will then be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations of the spatial relative descriptions used herein will be made.

[0075] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by orientation terms such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" etc. are generally based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. Without contrary description, these orientation terms do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present invention; the orientation terms "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0076] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a self-hardening PVD thin film, characterized in that, The preparation method of the self-hardening PVD film includes: Step S1: Pretreat the substrate in a multi-arc ion plating equipment; Step S2: Introduce nitrogen into the multi-arc ion plating equipment and keep a predetermined pressure in the multi-arc ion plating equipment, and turn on the arc TiAl target to deposit a TiAlN transition layer with a predetermined thickness on the surface of the pretreated substrate; Step S3: Introduce a mixed gas of nitrogen and a carbon source gas with a predetermined mass flow ratio and keep the total flow rate of the mixed gas unchanged to deposit a TiAlCN film with a predetermined thickness on the TiAlN transition layer, and control the surface droplet ratio of the TiAlCN film; Step S4: Detect and analyze the TiAlCN film; Step S5: Post-treat the qualified TiAlCN film.

2. The method for preparing a self-hardening PVD film according to claim 1, characterized in that, In the step S3, the mass flow ratio of the nitrogen and the carbon source gas is 10:1 - 100:

1.

3. The method for preparing a self-hardening PVD film according to claim 2, wherein In the step S3, the carbon source gas includes acetylene.

4. The method for preparing a self-hardening PVD film according to claim 3, wherein, In the step S3, the nitrogen is led to the surface of the arc cathode in the multi-arc ion plating equipment through a gas pipe; and / or, The acetylene is introduced into the multi-arc ion plating equipment through a gas pipe on the furnace wall of the multi-arc ion plating equipment.

5. The preparation method of the self-hardening PVD thin film according to claim 1, wherein, The hardness of the TiAlCN film in the step S3 is 30 GPa - 38 GPa.

6. The method for preparing a self-hardening PVD film according to claim 1, characterized in that, In the step S4, the detection and analysis include measuring the atomic ratio of C element, the atomic ratio of C element + N element and the surface droplet ratio in the TiAlCN film.

7. The method for preparing a self-hardening PVD film according to claim 1, wherein In the step S5, the atomic ratio of C element in the qualified TiAlCN film is 5 at% - 20 at%; and / or, The atomic ratio of C element + N element in the qualified TiAlCN film is 40 at% - 60 at%; and / or, The surface droplet ratio of the qualified TiAlCN film is less than or equal to 2.0%.

8. The method for preparing a self-hardening PVD film according to claim 1, characterized in that, In the step S5, the post-treatment method includes polishing or stamping.

9. The method for preparing a self-hardening PVD film according to any one of claims 1 to 8, characterized in that, The thickness of the TiAlN transition layer is 0.2 μm - 2.0 μm; and / or, The thickness of the TiAlCN film is 1.0 μm - 10 μm.

10. The method for preparing a self-hardening PVD thin film according to any one of claims 1 to 8, characterized in that, The process temperature in the preparation method of the self-hardening PVD film is 400 °C - 600 °C.

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