Cutter composite coating, preparation method and cutter

Abstract

The invention discloses a cutter composite coating, a preparation method and a cutter, and relates to the technical field of material surface treatment. An AlTiTaN base serves as a base layer attached to a tool base body, a tetrahedron amorphous carbon film layer serves as a functional top layer, and a transition layer with the AlTiTaN base / carbon element proportion gradually changing is arranged between the base layer and the top layer and serves as a supporting and combining part. The problem that in the prior art, due to the fact that the interface bonding force between a tool base body and a strengthening coating is weak, and the internal stress is large, the service life of a tool is short or the machining quality of the tool is poor is effectively solved. Besides, an innovative low-temperature deposition process is further developed for the coating, temperature contradiction in the deposition process is effectively coordinated, firm combination with the top layer can be achieved on the premise that the performance of the AlTiTaN base layer is not sacrificed, and the service life of the AlTiTaN base layer is prolonged. Therefore, the comprehensive performance coating with ultrahigh wear resistance, excellent lubricity, high bonding strength and long service life and the corresponding cutter are obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material surface treatment, in particular to a tool composite coating, a preparation method thereof and a tool. BACKGROUND

[0002] There is a big problem in processing printed circuit board. The ordinary micro-PCB tool has a fast wear speed and a large wear amount in processing printed circuit board, and the service life of the PCB tool is short. In addition, the cutting chips are easy to be blocked in the chip removal groove of the PCB tool in processing, which can seriously reduce the hole wall quality of the printed circuit board. In order to improve the service life of the PCB tool and the quality of processing printed circuit board, the surface of the micro-PCB tool needs to be treated, which can greatly improve the service life of the PCB tool. However, other problems are brought, such as low bonding force between the coating and the micro-PCB tool substrate, easy peeling of the coating and loss of the protection function, or poor drilling quality of the coated tool edge. SUMMARY

[0003] The main purpose of the present application is to improve the bonding of amorphous tetrahedral carbon coating and hard alloy substrate, and to prepare a tool composite coating with high surface coating hardness, good lubricity and strong bonding force between the coating and the tool substrate, and a corresponding tool.

[0004] To achieve the above purpose, the present application provides a tool composite coating, which comprises a base layer, a transition layer and a top layer arranged in sequence; wherein the base layer is arranged in adhesion with the tool substrate; the top layer is a tetrahedral amorphous carbon film layer; the composition of the base layer comprises AlTiTaN; the composition of the transition layer comprises AlTiTaN and carbon element, and the content of the carbon element in the transition layer increases from one end close to the base layer to one end close to the top layer.

[0005] In an embodiment, the thickness of the top layer is 0.2-1 μm.

[0006] In an embodiment, the thickness of the base layer is 0.5-2 μm.

[0007] In an embodiment, the thickness of the transition layer is 0.1-0.5 μm.

[0008] In an embodiment, the mole percentage of the N element in the base layer is 45-55%.

[0009] In an embodiment, the mole percentage of the Al element in the base layer is 25-35%.

[0010] In an embodiment, the mole percentage of the Ta element in the base layer is 5-20%.

[0011] In one embodiment, the top layer comprises a tetrahedral amorphous carbon film layer with a molar percentage of 75% or more sp. 3 Bonded carbon atoms.

[0012] In one embodiment, the molar percentage of carbon in the transition layer is not less than 20%.

[0013] The present invention also proposes a method for preparing the aforementioned composite coating for cutting tools, comprising the following steps: S1. Perform plasma etching on the cleaned tool substrate; S2. Deposit a base layer on the surface of the tool substrate after etching in step S1: Turn on the AlTiTa alloy arc target and introduce the reactive gas to perform deposition and obtain the base layer. S3. Turn on the magnetically filtered arc carbon target and continue deposition, while increasing the arc current of the carbon target from a certain value and correspondingly decreasing the arc current of the AlTiTa alloy arc target. When the arc current of the carbon target increases to another value, stop deposition to obtain a transition layer. S4. Stop the flow of reactive gas and shut off the AlTiTa alloy arc target, maintain the arc current of the carbon target unchanged, continue deposition to obtain the top layer, and complete the preparation of the tool composite coating.

[0014] In one embodiment, in step S1, the tool substrate is placed on a rotating support in a vacuum chamber, and the vacuum chamber is evacuated to a pressure of 5.0 × 10⁻⁶. -3 Pa ~ 9.0 × 10 -3 The vacuum chamber is heated to 400℃~550℃ and then cooled to 90℃~120℃. Argon gas is introduced to fill the vacuum chamber to 1.5Pa~3.5Pa. The ion source is then activated to perform plasma etching on the surface of the tool substrate for 20min~35min.

[0015] In one embodiment, a reactive gas is introduced to maintain the gas pressure at 0.4 Pa to 5.0 Pa, the rotation speed of the tool substrate support is controlled at 0.5 r / min to 5 r / min, the AlTiTa alloy arc target is turned on, and the initial target current density is controlled at 1.2 A / cm². 2 ~1.8A / cm 2 The bias voltage was set from -150V to -100V, and deposition was carried out for 8 to 15 minutes. Afterward, the target current density was linearly reduced to 0.6 A / cm². 2 ~0.9A / cm 2 The bias voltage is linearly reduced to (-80V) to (-50V), and deposition continues for 6 min to 12 min until the substrate temperature reaches 165℃ to 205℃, thus completing the preparation of the substrate.

[0016] In one embodiment, in step S3, the reaction temperature and the partial pressure of the reactant gas are kept constant, the magnetically filtered arc carbon target is turned on, and the arc current density is set to 0.5 A / cm². 2 ~0.8A / cm 2 Vapor deposition continued, and during the deposition process, the arc current of the carbon target was linearly increased to 1.2 A / cm. 2 ~1.6A / cm 2 Accordingly, the arc current of the AlTiTa alloy arc target is reduced from 0.6 A / cm. 2 ~0.9A / cm 2 Linearly decrease to 0.3 A / cm 2 ~0.5A / cm 2 Deposition time: 10-18 minutes; In one embodiment, in step S4, the reaction gas is stopped and the AlTiTa target is turned off. The current density and bias voltage of the carbon target are kept constant, and deposition continues for 15 min to 25 min. The target is then cooled to below 80°C in the furnace and removed from the furnace to complete the preparation of the tool composite coating.

[0017] In one embodiment, the reactant gas includes nitrogen.

[0018] The present invention also proposes a cutting tool, the cutting tool comprising a cutting tool substrate, the surface of which is provided with the cutting tool composite coating.

[0019] This invention designs a coating for PCB machining tools, using an AlTiTaX base as the base layer to adhere to the tool substrate, and a tetrahedral amorphous carbon film as the functional top layer. A gradient transition layer with a varying AlTiTaX base / carbon element ratio is placed between the base and top layers as a support and bonding area. This effectively solves the problems of weak interfacial bonding and high internal stress between the tool substrate and the reinforcing coating in existing technologies, which lead to short tool life or poor machining quality. Furthermore, this invention develops an innovative low-temperature deposition process for this coating, effectively coordinating the temperature imbalance during deposition. This allows for a strong bond between the AlTiTaX base layer and the top layer without sacrificing the performance of the AlTiTaX base layer, resulting in a comprehensive coating with ultra-high wear resistance, excellent lubricity, high bonding strength, and long lifespan, along with its corresponding tool. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 This is a comparison chart of the mechanical property test results of Example 1 and Comparative Example 1 in this invention; Figure 2 This is a comparison chart of the scratch test results of Example 1 and Comparative Example 2 in this invention; Figure 3 This is a comparison chart of the service life of Example 1 and Comparative Example 3 in this invention; Figure 4 This is a schematic diagram of the coating structure according to an embodiment of the present invention.

[0022] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0025] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0026] The technical problem solved by this application is that in order to improve the bonding force between the tetrahedral amorphous carbon film and the tool substrate, a transition layer needs to be introduced between them. However, since the transition layer itself has low hardness and poor wear resistance, it will become the weak link of the entire coating system during the wear process and fail first.

[0027] In related technologies, AlTiN-based coatings are used as hard coatings, but AlTiN-based coatings have a relatively high coefficient of friction and insufficient lubricity. During their research, the inventors explored a method to combine the advantages of tetrahedral amorphous carbon films and AlTiN-based coatings to prepare a "hard-slip" composite coating. Specifically, the bottom AlTiN-based coating provides strong support and wear resistance, while the top ta-C layer provides lubrication. However, the research revealed that combining these two technologies requires addressing the following technical challenges: First, AlTiN-based and tetrahedral amorphous carbon films differ greatly in crystal structure and coefficient of thermal expansion. Direct bonding between them will generate huge internal stress at the interface, becoming the source of crack initiation and propagation. Second, tetrahedral amorphous carbon films need to be deposited below 200℃ while AlTiN-based films need to be deposited above 400℃. The different requirements for process temperature during the preparation process can easily lead to the coating structure of either one failing to obtain optimal mechanical properties.

[0028] To solve the above technical problems, refer to Figure 4 This invention proposes a composite coating for cutting tools, comprising a base layer, a transition layer, and a top layer stacked sequentially; wherein the base layer is bonded to the cutting tool substrate; the top layer is a tetrahedral amorphous carbon film layer; the base layer is composed of AlTiTaN; the transition layer is composed of AlTiTaN and carbon, and the carbon content of the transition layer increases from the end near the base layer to the end near the top layer.

[0029] It should be noted that, in the preparation process of the substrate, the present invention enhances the bombardment of the substrate by introducing Ta elements with a large atomic mass, and supplements this with plasma parameter control, thereby enabling the coating to achieve a relatively dense structure at a lower temperature.

[0030] Furthermore, the addition of Ta (tantalum) to AlTiN-based materials can further refine the grains, which is beneficial for obtaining a dense, high-performance nanocrystalline structure, thereby improving the thermal stability, oxidation resistance, and red hardness of the substrate and making the substrate more supportive.

[0031] It should also be noted that during the deposition of the transition layer, the arc current of the carbon target is increased while the arc current of the AlTiTa alloy target is decreased accordingly. This allows for the alternating deposition of AlTiTaN layers and amorphous carbon layers, forming a layered structure with alternating AlTiTaN and amorphous carbon layers in the transition layer. On the side of the transition layer closer to the substrate, the amorphous carbon layer and the AlTiTaN layer form a coherent interface, effectively improving the bonding strength between the substrate and the transition layer. The side of the transition layer closer to the top layer contains almost no AlTiTaN nanocrystals, and the coating structure changes from columnar crystalline to amorphous. Therefore, the transition layer achieves a smooth transition from AlTiTaN nanocrystalline layers to amorphous carbon layers, effectively reducing interfacial stress distribution. Secondly, the transition layer acts as a temperature buffer in the process, allowing the deposition process to smoothly transition from a high-temperature range to a low-temperature range, rather than undergoing a sudden temperature switch. This helps reduce the additional thermal stress introduced into the entire coating system due to drastic temperature changes.

[0032] In one embodiment, the thickness of the top layer is 0.2 μm to 1 μm. The top layer is a tetrahedral amorphous carbon film layer, prepared using magnetically filtered arc technology to ensure high sp2. 3 Bond content.

[0033] In one embodiment, the thickness of the substrate is 0.5 μm to 2 μm. The substrate is based on AlTiN material, and the bombardment of the substrate is enhanced by introducing Ta elements with a large atomic mass, and supplemented by plasma parameter control, so that the coating can achieve a relatively dense structure at a lower temperature.

[0034] In one embodiment, the thickness of the transition layer is 0.1 μm to 0.5 μm. This layer achieves continuous compositional variation by precisely controlling the evaporation rates of the AlTi and C targets, forming a buffer zone with a smooth transition in mechanical properties.

[0035] By controlling the thickness range of different coatings, a more balanced stress distribution can be achieved, ensuring the bonding strength between the entire coating system and the tool substrate.

[0036] In one embodiment, the molar percentage of N element in the base layer is 45% to 55%; and / or, the molar percentage of Al element is 25% to 35%; and / or, the molar percentage of Ta element is 5% to 20%.

[0037] By controlling the elemental ratios in the base material, the thermal stability, oxidation resistance, and red hardness of the base layer were further enhanced, resulting in stronger support. By limiting the proportion of Ta, the densification effect of Ta on the base layer and its strengthening effect on the transition layer were further strengthened.

[0038] In one embodiment, the top layer comprises a tetrahedral amorphous carbon film layer with a molar percentage of 75% or more sp. 3 Bonded carbon atoms.

[0039] In one embodiment, the molar percentage of carbon in the transition layer is not less than 20%.

[0040] The present invention also proposes a method for preparing the aforementioned composite coating for cutting tools, comprising the following steps: S1. Perform plasma etching on the cleaned tool substrate; S2. Deposit a base layer on the surface of the tool substrate after etching in step S1: Turn on the AlTiTa alloy arc target and introduce the reactive gas to perform deposition and obtain the base layer. S3. Turn on the magnetically filtered arc carbon target and continue deposition, while increasing the arc current of the carbon target from a certain value and correspondingly decreasing the arc current of the AlTiTa alloy arc target. When the arc current of the carbon target increases to another value, stop deposition to obtain a transition layer. S4. Stop the flow of reactive gas and shut off the AlTiTa alloy arc target, maintain the arc current of the carbon target unchanged, continue deposition to obtain the top layer, and complete the preparation of the tool composite coating.

[0041] In one embodiment, in step S1, the tool substrate is placed on a rotating support in a vacuum chamber, and the vacuum chamber is evacuated to a pressure of 5.0 × 10⁻⁶. -3 Pa ~ 9.0 × 10 -3 The vacuum chamber is heated to 400℃~550℃ and then cooled to 90℃~120℃. Argon gas is introduced to fill the vacuum chamber to 1.5Pa~3.5Pa. The ion source is then activated to perform plasma etching on the surface of the tool substrate for 20min~35min.

[0042] In one embodiment, in step S2, during the initial stage of deposition, a high target current and a high substrate bias voltage are used to achieve dense nucleation and growth of the thin film at low temperatures by utilizing the strong ion bombardment effect. As deposition progresses, the substrate temperature gradually increases due to the accumulated deposition heat. In the later stage of deposition, to avoid excessively high temperatures, the AlTiTa current and substrate bias voltage are gradually and linearly reduced, forming a gradient process from high-energy bombardment to gentle growth.

[0043] In a specific embodiment, in step S2, a reactive gas is introduced to maintain the gas pressure at 0.4 Pa to 5.0 Pa, the rotation speed of the tool substrate support is controlled at 0.5 r / min to 5 r / min, the AlTiTa alloy arc target is turned on, and the initial target current density is controlled at 1.2 A / cm². 2 ~1.8A / cm 2Bias voltage (-150V) ~ (-100V); deposition time 8 min ~ 15 min; then target current density linearly reduced to 0.6 A / cm² over 4 min ~ 8 min. 2 ~0.9A / cm 2 The bias voltage is linearly reduced to (-80V) to (-50V), and deposition continues for 6 min to 12 min until the substrate temperature reaches 165℃ to 205℃, thus completing the preparation of the substrate.

[0044] It should be noted that step S2 employs a gradient preparation process with high-energy bombardment in the early stage and gradual energy reduction in the later stage, combined with heavy ion bombardment with large atomic numbers, to prepare a high-performance AlTiN-based substrate at low temperature, thus resolving the process contradiction between substrate performance and top layer temperature.

[0045] In one specific embodiment, in step S3, the magnetically filtered arc carbon target is turned on and the arc current density is set to 0.5 A / cm. 2 ~0.8A / cm 2 During deposition, the arc current of the carbon target was linearly increased to 1.2 A / cm. 2 ~1.6A / cm 2 Accordingly, the arc current of the AlTiTa alloy arc target is reduced from 0.6 A / cm. 2 ~0.9A / cm 2 Linearly decrease to 0.3 A / cm 2 ~0.5A / cm 2 Deposition time is 10-18 minutes to complete the preparation of the transition layer.

[0046] In a more specific embodiment, in step S3, during the deposition process, the arc current of the carbon target is linearly increased to 1.2 A / cm² within 6 to 10 minutes. 2 ~1.6A / cm 2 Accordingly, the arc current of the AlTiTa alloy arc target is reduced from 0.6 A / cm. 2 ~0.9A / cm 2 Linearly decrease to 0.3 A / cm 2 ~0.5A / cm 2 In one embodiment, in step S4, the incoming reactive gas is stopped and the AlTiTa target is turned off. The current density and bias voltage of the carbon target are kept constant, and deposition continues for 15 min to 25 min. The target is then cooled to below 80°C in the furnace and removed from the furnace to complete the preparation of the tool composite coating.

[0047] In one embodiment, the reactant gas includes nitrogen.

[0048] The present invention also proposes a cutting tool, comprising a cutting tool substrate, wherein the surface of the cutting tool substrate is provided with the above-mentioned cutting tool composite coating, the thickness of the cutting tool composite coating being 1μm~3μm.

[0049] The present invention will be further illustrated below through specific embodiments: The raw materials, reagents, or devices used in the embodiments of this invention are all commercially available. Unless otherwise specified, this invention does not impose any restrictions on the source of raw materials.

[0050] Example 1 The tool composite coating in Example 1 comprises layers sequentially stacked from the tool substrate: The substrate is made of AlTiTaN with a thickness of 0.5 μm; the transition layer is made of AlTiTaN / C with a thickness of 0.2 μm; and the top layer is made of tetrahedral amorphous carbon with a thickness of 0.3 μm.

[0051] The preparation method of the composite coating for the cutting tool in Example 1 includes the following steps: S1. Place the cemented carbide PCB micro-drill into a PVD coating equipment equipped with a magnetically filtered arc source, heat to 450℃, and evacuate to 6.0×10⁻⁶. -3 Pa, then cooled to 100℃; argon gas was introduced to fill the vacuum chamber to 0.1Pa~1.0Pa, the ion source was started, and plasma etching was performed for 25min; S2. Turn off Ar gas and introduce nitrogen gas, maintaining the gas pressure at 2.0 Pa. Turn on the AlTiTa alloy arc target, with an initial target current density of 1.5 A / cm² and a substrate bias voltage of -120 V. Deposit for 15 min, then linearly reduce the target current density to 0.8 A / cm² within 5 min, and linearly reduce the bias voltage to -80 V before continuing deposition for 10 min. The substrate temperature is 185±10℃, completing the preparation of the substrate. S3. Turn on the magnetically filtered arc carbon target. Within 6 minutes, the arc current density increases linearly from 0.6 A / cm² to 1.2 A / cm², while the AlTiTa target current density decreases linearly from 0.8 A / cm² to 0.5 A / cm² and then continues deposition for 4 minutes; the preparation of the transition layer is completed. S4. Turn off the nitrogen source and AlTiTa target, magnetically filter the carbon target with a current density of 1.2 A / cm², bias voltage of -80 V, and deposit for 15 min; complete the preparation of the top layer, cool it in the furnace to below 80°C and remove it from the furnace to obtain the tool coating.

[0052] In Example 1, the molar percentages of Al, Ti, and Ta in the AlTiTa alloy target are 60:30:10.

[0053] Example 2 The tool composite coating in Example 2 comprises layers sequentially stacked from the tool substrate: The substrate is made of AlTiTaN with a thickness of 0.6 μm; the transition layer is made of AlTiTaN / C with a thickness of 0.3 μm; and the top layer is made of tetrahedral amorphous carbon with a thickness of 0.6 μm.

[0054] The preparation method of the composite coating for the cutting tool in Example 2 includes the following steps: S1. Place the cemented carbide PCB micro-drill into a PVD coating equipment equipped with a magnetically filtered arc source, heat to 500℃, and evacuate to 8.0×10. -3 Pa, then cooled to 120℃; argon gas was introduced to fill the vacuum chamber to 0.1Pa~1.0Pa, the ion source was started, and plasma etching was performed for 35min; S2. Turn off Ar gas and introduce nitrogen gas, maintaining the gas pressure at 3.5 Pa. Turn on the AlTiTa alloy arc target with an initial target current density of 1.8 A / cm² and a substrate bias voltage of -150 V. After deposition for 15 min, linearly reduce the target current density to 0.9 A / cm² within 8 min and linearly reduce the bias voltage to -80 V. Continue deposition for another 12 min at a substrate temperature of 195±10°C. The preparation of the substrate is now complete. S3. Turn on the magnetically filtered arc carbon target. Within 8 minutes, the arc current density increases linearly from 0.8 A / cm² to 1.6 A / cm², while the AlTiTa target current density decreases linearly from 0.9 A / cm² to 0.5 A / cm² and then continues deposition for 6 minutes; the preparation of the transition layer is completed. S4. Turn off the nitrogen source and AlTiTa target, magnetically filter the carbon target with a current density of 1.6 A / cm², bias voltage of -100 V, and deposit for 25 min; complete the preparation of the top layer, cool it in the furnace to below 80°C and remove it from the furnace to obtain the tool coating.

[0055] In Example 2, the molar percentages of Al, Ti, and Ta in the AlTiTa alloy target are 50:40:10.

[0056] Example 3 The composite coating for the cutting tool in Example 3 comprises layers sequentially stacked from the cutting tool substrate: The substrate is made of AlTiTaN with a thickness of 0.4 μm; the transition layer is made of AlTiTaN / C with a thickness of 0.5 μm; and the top layer is made of tetrahedral amorphous carbon with a thickness of 0.4 μm.

[0057] The preparation method of the composite coating for the cutting tool in Example 3 includes the following steps: S1. Place the cemented carbide PCB micro-drill into a PVD coating equipment equipped with a magnetically filtered arc source, heat to 420℃, and evacuate to 5.5×10⁻⁶. -3 Pa, then cooled to 90℃; argon gas was introduced to fill the vacuum chamber to 0.1Pa~1.0Pa, the ion source was started, and plasma etching was performed for 20min; S2. Turn off Ar gas and introduce nitrogen gas, maintaining the gas pressure at 1.5 Pa. Turn on the AlTiTa alloy arc target with an initial target current density of 1.2 A / cm² and a substrate bias voltage of -100 V. After deposition for 10 min, linearly reduce the target current density to 0.6 A / cm² within 4 min and linearly reduce the bias voltage to -50 V. Continue deposition for another 6 min at a substrate temperature of 175±10°C. The preparation of the substrate is now complete. S3. Turn on the magnetically filtered arc carbon target. Within 10 min, the arc current density increases linearly from 0.5 A / cm² to 1.4 A / cm², while the AlTiTa target current density decreases linearly from 0.6 A / cm² to 0.3 A / cm² and then continues deposition for 8 min; the preparation of the transition layer is completed. S4. Turn off the nitrogen source and AlTiTa target, magnetically filter the carbon target with a current density of 1.4 A / cm², bias voltage of -120 V, and deposit for 18 min; complete the preparation of the top layer, cool it in the furnace to below 80°C and remove it from the furnace to obtain the tool coating.

[0058] In Example 4, the molar percentages of Al, Ti, and Ta in the AlTiTa alloy target were 45:45:10.

[0059] Example 4 The tool composite coating in Example 4 comprises layers sequentially stacked from the tool substrate: The substrate is made of AlTiTaN with a thickness of 0.3 μm; the transition layer is made of AlTiTaN / C with a thickness of 0.4 μm; and the top layer is made of tetrahedral amorphous carbon with a thickness of 0.5 μm.

[0060] The preparation method of the composite coating for the cutting tool in Example 4 includes the following steps: S1. Place the cemented carbide PCB micro-drill into a PVD coating equipment equipped with a magnetically filtered arc source, heat to 480℃, and evacuate to 7×10. -3 Pa, then cooled to 110℃; argon gas was introduced to fill the vacuum chamber to 0.1Pa~1.0Pa, the ion source was started, and plasma etching was performed for 30min; S2. Turn off Ar gas and introduce nitrogen gas, maintaining the gas pressure at 2.8 Pa. Turn on the AlTiTa alloy arc target with an initial target current density of 1.6 A / cm² and a substrate bias voltage of -130 V. After deposition for 8 min, linearly reduce the target current density to 0.7 A / cm² within 6 min and linearly reduce the bias voltage to -65 V. Continue deposition for another 6 min at a substrate temperature of 190±10°C. The preparation of the substrate is now complete. S3. Turn on the magnetically filtered arc carbon target. Within 7 minutes, the arc current density increases linearly from 0.7 A / cm² to 1.5 A / cm², while the AlTiTa target current density decreases linearly from 0.7 A / cm² to 0.5 A / cm² and then continues deposition for 5 minutes; the preparation of the transition layer is completed. S4. Turn off the nitrogen source and AlTiTa target, magnetically filter the carbon target with a current density of 1.5 A / cm², bias voltage of -80 V, and deposit for 20 min; complete the preparation of the top layer, cool it in the furnace to below 80°C and remove it from the furnace to obtain the tool coating.

[0061] In Example 4, the molar percentages of Al, Ti, and Ta in the AlTiTa alloy target were 40:50:10.

[0062] Comparative Example 1 The tool coating in Comparative Example 1 has a 2 μm thick AlTiTaN layer on the surface of the tool substrate; the preparation process of this coating is the same as in Example 1.

[0063] Comparative Example 2 In Comparative Example 2, the tool coating consists of a 0.5 μm thick AlTiTaN base layer and a 0.3 μm thick tetrahedral amorphous carbon top layer, layered sequentially on the tool substrate surface. The preparation process is the same as in Example 1.

[0064] Comparative Example 3 In Comparative Example 3, the tool coating consists of the following layers stacked sequentially on the tool substrate surface: a base layer of AlTiN with a thickness of 0.5 μm; a transition layer of AlTiTaN / C with a thickness of 0.2 μm; and a top layer of tetrahedral amorphous carbon with a thickness of 0.3 μm.

[0065] Performance testing: (1) The instrumented indentation hardness and elastic modulus of the tool coatings prepared in Example 1 and Comparative Example 1 were measured. The results are shown in the figure. Figure 1 ; (2) The tool coatings prepared in Example 1 and Comparative Example 2 were subjected to scratch tests, and the results are shown in the figure. Figure 1 ; (3) When the coated cutting tools prepared in Example 1 and Comparative Example 3 were used to process PCB circuit boards, their service life was compared. The test results are shown in [the table below].Figure 3 .

[0066] Through the Figure 1 Analysis showed that the composite coating of the cutting tool in Example 1 had a hardness of 32.8 ± 1.2 GPa, while the thickness of the 2 μm AlTiN single coating in Comparative Example 1 was 28.5 ± 1.1 GPa. Therefore, the composite coating of the cutting tool of the present invention has sufficiently high hardness; combined with Figure 2 In Comparative Example 2, the double-layer coating without a gradient transition layer exhibited interlayer peeling when the loading force increased to approximately 24 N, and peeling from the substrate occurred when the loading force increased to approximately 38 N. In contrast, the tool composite coating in Example 1 only showed interlayer peeling when the loading force increased to approximately 42 N, and peeling from the substrate occurred when the loading force increased to approximately 58 N. Combined with... Figure 3 The tool composite coating in Example 1 has a service life of approximately 22% longer when micro-drilling PCB circuit boards compared to Comparative Example 3.

[0067] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A cutting tool composite coating, characterized by, The tool composite coating comprises a base layer, a transition layer and a top layer which are sequentially stacked; The top layer is a tetrahedral amorphous carbon film layer; The base layer comprises AlTiTaN; The transition layer comprises AlTiTaN and carbon elements, and the content of the carbon elements in the transition layer increases from one end close to the base layer to one end close to the top layer.

2. The tool composite coating according to claim 1, characterized in that The thickness of the top layer is 0.2-1 μm; And / or, the thickness of the base layer is 0.5-2 μm; And / or, the thickness of the transition layer is 0.1-0.5 μm.

3. The tool composite coating according to claim 1, wherein In the base layer, the mole percentage of the N element is 45-55%; And / or, in the base layer, the mole percentage of the Al element is 25-35%; And / or, in the base layer, the mole percentage of the Ta element is 5-20%.

4. The tool composite coating according to claim 1, wherein In the top layer, the tetrahedral amorphous carbon film layer includes sp 3 bonded carbon atoms.

5. The tool composite coating according to claim 1, wherein In the transition layer, the mole percentage of the carbon element is not less than 20%.

6. A method of producing a tool composite coating as claimed in any of claims 1 to 5, characterized in that The preparation method of the tool composite coating comprises the following steps: S1, plasma etching the cleaned tool base body; S2, depositing a base layer on the surface of the tool base body etched in the step S1: turning on an AlTiTa alloy arc target and inputting a reaction gas to deposit a base layer; S3, turning on a magnetic filter arc carbon target to continue depositing, and increasing the arc current of the carbon target from a value, and correspondingly gradually reducing the arc current of the AlTiTa alloy arc target, stopping depositing when the arc current of the carbon target is increased to another value, and preparing a transition layer; S4, stopping inputting the reaction gas and turning off the AlTiTa alloy arc target, maintaining the arc current of the carbon target unchanged, and continuing depositing to prepare a top layer, and completing the preparation of the tool composite coating.

7. The method of producing a cutting tool composite coating according to claim 6, wherein In an embodiment, in the step S1, the tool base is arranged on a rotating support in a vacuum chamber, the vacuum chamber is vacuumized to a pressure of 5.0x10 -3 Pa~9.0x10 -3 Pa, heated to 400℃~550℃, and then cooled to 90℃~120℃; argon is introduced to fill the cavity of the vacuum chamber to a pressure of 1.5Pa~3.5Pa, the ion source is started, and the surface of the tool base is plasma etched for 20min~35min.

8. The method of producing a cutting tool composite coating according to claim 7, wherein In the step S2, the reaction gas is introduced to maintain the gas pressure at 0.4 Pa to 5.0 Pa, the rotating speed of the holder of the tool base is controlled at 0.5 r / min to 5 r / min, the AlTiTa alloy arc target is turned on, the initial target current density is controlled at 1.2 A / cm 2 ~1.8 A / cm 2 , the bias voltage is controlled at (-150 V) to (-100 V), and the deposition is performed for 8 min to 15 min; then the target current density is linearly reduced to 0.6 A / cm 2 ~0.9 A / cm 2 , the bias voltage is linearly reduced to (-80 V) to (-50 V), the deposition is continuously performed for 6 min to 12 min, the base temperature reaches 165 ℃ to 205 ℃, and the preparation of the base layer is completed. and / or, in the step S3, the magnetic filtered arc carbon target is turned on and the arc current density is set to 0.5 A / cm 2 ~0.8 A / cm 2 , the gas phase deposition is continued, and during the deposition, the arc current of the carbon target is linearly increased to 1.2 A / cm 2 ~1.6 A / cm 2 , and the arc current of the AlTiTa alloy arc target is linearly decreased from 0.6 A / cm 2 ~0.9 A / cm 2 to 0.3 A / cm 2 ~0.5 A / cm 2 , and the deposition is performed for 10 min~18 min; And / or, in the step S4, stopping inputting the reaction gas and turning off the AlTiTa target, maintaining the current density and bias of the carbon target unchanged, continuing depositing for 15-25 min, cooling in the furnace to below 80℃, and completing the preparation of the tool composite coating.

9. The method of claim 7, wherein the coating is formed by a physical vapor deposition process. The reaction gas comprises nitrogen.

10. A cutting tool characterized by The tool comprises a tool base body, and the surface of the tool base body is provided with the tool composite coating according to any one of claims 1-5.

Images