Metal-free coating film containing tetrahedral amorphous carbon without hydrogen

Abstract

The present invention relates to a coated substrate (preferably a coated tool) including a coated surface for a manufacturing process (for example, a machining process or a forming process), wherein the coated surface is formed by a substrate surface formed of a first material (1) and a coating film system (preferably an arc PVD deposition coating film system) applied to the substrate surface, the coating film system includes an amorphous carbon film (100), and the amorphous carbon film (100) has an sp 3 bonding ratio exceeding the sp 2 bonding ratio and is a tetrahedral hydrogen-free amorphous carbon film. Furthermore, the present invention relates to a method for manufacturing a coated substrate.

Description

Technical Field

[0001] The present invention relates to a coated substrate (in particular, a coated tool) having a metal-free coating film including a tetrahedral hydrogen-free amorphous carbon film having excellent hardness, and a method for manufacturing the coated substrate.

Background Art

[0002] Ohtani et al. propose in European Patent No. 1266979 B1 to manufacture an amorphous carbon coated tool by specifying the components of the substrate and the thickness of the amorphous carbon film. The method proposed in European Patent No. 1266979 B1 for manufacturing an amorphous carbon coated tool includes the steps of supporting a substrate of WC-based cemented carbide in a vacuum chamber, applying a zero or negative DC bias to the substrate, and evaporating graphite as a raw material to form an amorphous carbon film. The maximum thickness of the amorphous carbon film at the cutting corner is controlled to be from 0.05 μm to 0.8 μm. The use of graphite as a material source for forming an amorphous carbon film by physical vapor deposition in an atmosphere without hydrogen is proposed, and as a result, the amorphous carbon film contains 5% or less hydrogen atoms. Further, the cathode arc ion plating method and use at a temperature between 50 °C and 350 °C are particularly proposed.

[0003] Furthermore, Ohtani et al. proposed using appropriate measures to prevent particle scattering from graphite materials, for example, by growing the film using low energy or using a filter under a magnetic field to improve the surface roughness of the amorphous carbon film. The proposed roughness is between 0.002 μm and 0.05 μm in Ra. The proposed Knoop hardness is between 20 GPa and 50 GPa. The amorphous carbon film is transparent in the visible region, exhibits interference colors, and the color of the coating film can be iridescent corresponding to multiple color tones instead of a single color. The coating tool has an intermediate layer provided between the substrate and the amorphous carbon film to enhance the adhesion of the amorphous carbon film. Here, the intermediate layer can use at least one type of element selected from the group consisting of elements from Group IVa, Va, VIa, and IIIb of the periodic table, and elements from Group IVb of the periodic table excluding C, or carbides of at least one type of element selected from the group consisting of these elements. In particular, the intermediate layer includes at least one type of element selected from the group consisting of the elements Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Si, or carbides of at least one type of element selected from the group consisting of these elements, and it is proposed that the thickness of the intermediate layer is between 0.5 nm and 10 nm.

[0004] Becker et al. proposed a method for producing a hydrogen-free amorphous carbon coating film in International Publication No. WO 2021 / 019084A1, which has a lower hardness near the substrate and on the outer surface of the coating film, and a higher hardness anywhere between these two regions. To obtain these desired coating transitions, Becker et al. proposed controlling the bias voltage and substrate temperature, and using the cathode arc evaporation technique, and applying a low target current in the range of 25 A to 35 A for the deposition of the hydrogen-free amorphous carbon coating film. Furthermore, Becker et al. proposed depositing a metal layer as an adhesion layer to enhance the adhesion between the substrate and the hydrogen-free amorphous carbon coating film. Such a coating solution is very suitable for components used in automotive applications, but not suitable for tools used in cutting or forming applications.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The main object of the present invention is a coated substrate (especially a coated tool) that exhibits tribological properties comparable to those of an anhydrous tetrahedral amorphous carbon coating film, preferably having higher toughness than the prior art, and is used in cutting or forming applications regardless of the hardness of the substrate. In particular, for tools used in such applications, the present invention aims to provide a coated substrate that achieves high performance and increased lifespan (i.e., in the case of a coated tool, increased tool performance and increased lifespan).

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0007] The present invention provides a method for forming a coating film, particularly, as a first aspect, a coated substrate, and as a second aspect, a method for manufacturing the coated substrate of the invention.

[0008] The main embodiment of the coated substrate according to the present invention is the coated substrate according to claim 1, preferably a coating tool including a coated surface for a manufacturing process (for example, a machining process or a forming process), wherein the coated surface is formed by a substrate surface formed of a first material and a coating film system (preferably, an arc PVD deposition coating film system (PVD = physical vapor deposition)) applied to the substrate surface, the coating film system includes an amorphous carbon film, and the amorphous carbon film is a tetrahedral hydrogen-free amorphous carbon film in which the ratio of the sp3 bonding ratio of C-C bonds exceeds the ratio of the sp2 bonding ratio, providing a coated substrate.

[0009] According to the present invention, preferably, the amorphous carbon film 100 is designed to include various ratios of the ratio of the sp 2 bonding ratio of C-C bonds to the ratio of the sp 3 bonding ratio, and the ratios continuously and / or stepwise increase from the lower part to the upper part of the amorphous carbon film 100, the lower part being the region of the amorphous carbon film 100 closest to the substrate, and the upper part being the region of the amorphous carbon film 100 farthest from the substrate.

[0010] According to a preferred embodiment, the amorphous carbon film 100 is formed as a multilayer film including at least two tetrahedral hydrogen-free amorphous carbon layers, and the at least two layers are a lower layer 120 including the region of the amorphous carbon film 100 closest to the substrate, and an upper layer 150 including the region of the amorphous carbon film 100 farthest from the substrate, wherein the ratio of the ratio of the sp 2 bonding ratio of C-C bonds to the ratio of the sp 3 bonding ratio is higher for the upper layer 150 than for the ratio along the thickness of the lower layer 120 is.

[0011] In the most preferred embodiment, the upper layer 150 is the outermost layer of the amorphous carbon film 100. Thereby, particularly when the coated tool is used for cutting and forming applications, the very high tool performance of the thus-coated tool can be particularly achieved.

[0012] To enhance the adhesion of the amorphous carbon film 100 to the substrate, preferably, the amorphous carbon film 100 is attached to the substrate surface in such a way that an interface layer 10 is formed between the first material 1 of this substrate surface and the amorphous carbon film 100. The interface layer 10 is made of a carbon-containing material, and the carbon-containing material is formed of the first material and carbon implanted into the first material. The thickness of the interface layer 10 is at least 3 nm.

[0013] To further enhance the adhesion of the amorphous carbon film 100 to the substrate, a transition layer 30 is attached between the interface layer 10 and the amorphous carbon film 100. The transition layer 30 is a carbon layer that improves the interface transition between the interface layer 10 and the amorphous carbon film 100.

[0014] Preferably, the transition layer 30 is a tetrahedral amorphous hydrogen-free carbon layer.

[0015] According to a very preferred embodiment of the present invention, the amorphous carbon film 100 has a low residual compressive stress corresponding to a value with an absolute value of 5.5 GPa or less, preferably in the range of 2.8 GPa to 5.5 GPa, more preferably in the range of 3 GPa to 5 GPa, as measured by using, in particular, Micro-Epsilon film internal stress measurement.

[0016] Furthermore, preferably, the amorphous carbon film 100 includes at least a portion (e.g., a layer) exhibiting both characteristics in the range of 7 to 13, preferably in the range of 8 to 12, of the ratio of the average Young's modulus of the amorphous carbon film measured in GPa to the average hardness of the amorphous carbon film, as measured by using standard nanoindentation techniques.

[0017] Preferably, the lower layer 120 has a hardness in the range of 30 GPa to 50 GPa, preferably in the range of 30 GPa to 45 GPa, and preferably, the upper layer 150 has a hardness in the range of 50 GPa to 80 GPa, more preferably in the range of 55 GPa to 80 GPa, particularly in the range of 55 GPa to 75 GPa.

[0018] Preferably, the lower layer 120 has a Young's modulus in the range of 250 GPa to 350 GPa, and preferably, the upper layer 150 has a Young's modulus in the range of 500 GPa to 800 GPa.

[0019] Preferably, the transition layer 30 has a hardness in the range of 50 GPa to 80 GPa, preferably in the range of 55 GPa to 80 GPa, or in the range of 55 GPa to 75 GPa, and / or a Young's modulus in the range of 500 GPa to 800 GPa.

[0020] Depending on the application, an amorphous carbon film (100) having a specific color or combination of colors can be produced.

[0021] Therefore, in some cases, for example, in the presence of visible light, an amorphous carbon film 100 having an iridescent appearance showing a plurality of color tones instead of a single color to the human eye can be produced, and in other cases, for example, in the presence of visible light, an amorphous carbon film 100 showing a single color having a black or gray appearance to the human eye can be produced.

[0022] According to a further preferred embodiment of the present invention, the amorphous carbon film 100 has at least one layer including the highest ratio of the sp 2 bonding ratio of C-C bonds to the ratio of the sp 3 bonding ratio along the thickness of the entire amorphous carbon film 100. Preferably, for example, in order to obtain maximum cutting or forming performance, the sp 2 bonding ratio of C-C bonds to the ratio of the sp 3 bonding ratio along the thickness of the entire amorphous carbon film 100. At least one layer including the highest ratio is the upper layer 150.

[0023] To achieve the desired performance, preferably, the interface layer 10 is in the range of 3 nm to 200 nm, more preferably in the range of 3 nm to 100 nm, and even more preferably in the range between 3 nm and 50 nm, and / or the thickness of the transition layer 30 is in the range of 10 nm to 200 nm, preferably in the range of 15 nm to 100 nm, and more preferably in the range of 15 nm to 70 nm.

[0024] Similarly, more preferably, the thickness of the lower layer 120 is in the range of 30 nm to 2000 nm, preferably in the range of 30 nm to 500 nm, and more preferably in the range of 50 nm to 300 nm, and / or the thickness of the upper layer 150 is in the range of 50 nm to 1000 nm, preferably in the range of 50 nm to 500 nm, and more preferably in the range of 70 nm to 350 nm.

[0025] To achieve excellent wear resistance and toughness, preferably, the average hardness of the amorphous carbon film 100 is in the range between 50 GPa and 80 GPa, preferably in the range between 50 GPa and 70 GPa, and / or the average Young's modulus of the amorphous carbon film 100 is in the range between 500 GPa and 800 GPa, more preferably in the range between 600 GPa and 750 GPa.

[0026] Preferably, the amorphous carbon film according to the present invention exhibits a coefficient of friction measured by a ball-on-disk test in the range between 0.05 and 0.15.

[0027] The present invention includes not only the above-described embodiments in separate forms, but also all possible combinations of the above-described embodiments.

[0028] A preferred method for manufacturing a coated substrate according to any of the above-described embodiments and combinations of the above-described embodiments includes the following steps ·Providing a substrate having a surface formed of a first material 1 to be coated; ·Depositing an amorphous carbon film 100 by using a PVD process, the PVD process including cathodic arc evaporation of one or more graphite targets and application of a negative bias voltage to the substrate to be coated, the ratio of the sp3 bonding ratio of C-C bonds to the sp2 bonding ratio along the thickness of the amorphous carbon film having a minimum value at the beginning of the deposition of the amorphous carbon film 100 and a minimum value at the end of the deposition of the amorphous carbon film, and changing the ratio of the sp3 bonding ratio of C-C bonds to the sp2 bonding ratio along the thickness of the amorphous carbon film in such a way that the absolute value of the bias voltage is changed during the deposition of the amorphous carbon film 100, and the absolute value of the applied bias voltage at the beginning of the deposition process of the amorphous carbon film 100 is lower than the absolute value of the applied bias voltage at the end of the deposition process of the amorphous carbon film 100; including.

[0029] The absolute bias voltage applied during the deposition of the amorphous carbon film 100 is preferably selected to vary in the range from 0 V to 200 V, more preferably in the range from 10 V to 180 V, and even more preferably in the range from 10 V to 150 V.

[0030] In the case of depositing different layers within the amorphous carbon film 100, the inventor recommends maintaining as constant a bias voltage value as possible for the deposition of each different layer so as to have the same defined characteristics.

[0031] The arc current applied to one or more graphite targets during the deposition of the amorphous carbon film 100 is preferably selected to be a value in the range from 50 A to 110 A.

[0032] During the deposition of the amorphous carbon film 100, preferably, the lower layer 120 is first deposited and then the upper layer 150 is deposited. The absolute value of the bias voltage used during the deposition of the lower layer 120 is lower than the absolute value of the bias voltage used during the deposition of the upper layer 150. More preferably, · For the deposition of the lower layer (120), a negative bias voltage in the range of an absolute value from 0 V to 50 V and an arc current in the range of 50 A to 110 A are used, and / or · For the deposition of the upper layer (150), a negative bias voltage in the range of an absolute value from 50 V to 200 V, preferably in the range of 50 V to 180 V, more preferably in the range of 50 V to 150 V, and an arc current in the range of 50 A to 110 A are used.

[0033] The manufacturing method preferably includes the following steps when forming the interface layer 10. · Before depositing the amorphous carbon film 100, the interface layer 10 is manufactured by colliding carbon ions generated from at least one carbon target (preferably, at least one carbon target is a graphite target) with the first material 1. In this way, it is a processing step of forming the carbon implantation material constituting the interface layer 10. Here, preferably, a PVD process including an arc evaporation technique is used. The PVD process preferably generates carbon ions by applying an arc current in the range of 30 A to 50 A and using a bias voltage in the range between 400 V and 1000 V. including.

[0034] The manufacturing method preferably includes the following steps when forming the transition layer 30. ·A processing step of manufacturing a transition layer (30) by using a PVD process after the adhesion of the interface layer (10) and before the adhesion of the amorphous carbon film (100), wherein the PVD process includes cathode arc evaporation of one or more graphite targets and application of a negative bias voltage to the substrate to be coated, changing the absolute value of the bias voltage during the adhesion of the transition layer (30), preferably, at the beginning of the adhesion process of the transition layer (30), the absolute value of the applied bias voltage is the same as the absolute value used for the formation of the interface layer (10), and is decreased to an absolute value in the range of 150V to 200V including.

[0035] Preferably, the amorphous carbon film (100) is deposited by maintaining the processing temperature in the range of 70 to 180, preferably in the range of 80°C to 170°C, more preferably in the range of 100°C to 140°C.

[0036] A method of forming an interface layer between a first material on the substrate surface and the amorphous carbon film, and depositing the amorphous carbon film on this substrate surface, the interface layer is composed of a first material implanted with carbon, and the thickness of the interface layer is at least 3nm.

[0037] Therefore, according to the present invention, it is as follows. The amorphous carbon film is designed such that the ratio of the sp3 bonding rate of C-C bonds to the ratio of the sp2 bonding rate varies along the thickness of the amorphous carbon film, preferably, this ratio is considered to increase from the lower part to the upper part of the amorphous carbon film. The amorphous carbon film is considered to include at least one layer in which the ratio of the sp3 bonding rate of C-C bonds to the ratio of the sp2 bonding rate is maximized along the thickness of the amorphous carbon film. At least one layer in which the ratio of the sp3 bonding rate of C-C bonds to the ratio of the sp2 bonding rate is maximized along the thickness of the amorphous carbon film is preferably deposited as the outermost layer 150 (also called the upper layer 150) of the amorphous carbon film 100. Preferably, the amorphous carbon film 100 can be deposited as a multilayer (i.e., including at least two layers), and these at least two layers are considered to be designed in such a way that an excellent combination of toughness and low residual compressive stress can be achieved. In order to have this technical effect, these at least two layers are the lower layer 120 and the upper layer 150, and the ratio of the sp3 bonding ratio of C-C bonds to the sp2 bonding ratio along the thickness of the upper layer 150 is higher than the ratio of the sp3 bonding ratio of C-C bonds to the sp2 bonding ratio along the thickness of the lower layer 120. The amorphous carbon film 100 is transparent in the visible region and can include at least a portion (e.g., a layer) that exhibits an interference color. The color of the amorphous carbon film can be iridescent corresponding to a plurality of color tones instead of a single color, or it is considered that the amorphous carbon film 100 can include at least a portion (e.g., a layer) that exhibits a specified color (e.g., a black appearance). Preferably, the amorphous carbon film is considered to include at least a portion (e.g., a layer) that exhibits both characteristics in the range of 7 to 13, preferably in the range of 8 to 12, of the ratio of the average Young's modulus of the amorphous carbon film measured in GPa by using a standard nanoindentation technique corresponding to the average hardness of the amorphous carbon film. The thickness of the interface layer is considered to be in the range of 3 nm to 200 nm, preferably in the range of 3 nm to 100 nm. More preferably, the thickness of the interface layer can be considered to be in the range between 3 nm and 50 nm. It is also considered that the interface layer does not contain droplets. The average hardness of the amorphous carbon film is considered to be in the range between 50 GPa and 80 GPa, preferably in the range between 50 GPa and 70 GPa. The average Young's modulus of the amorphous carbon film can be in the range between 500 GPa and 800 GPa, preferably in the range between 600 GPa and 750 GPa. The amorphous carbon film may be formed as a multilayer film including at least two tetrahedral hydrogen-free amorphous carbon layers, preferably more than two tetrahedral hydrogen-free amorphous carbon layers. The amorphous carbon film can exhibit a coefficient of friction measured by a ball-on-disk test in the range between 0.05 and 0.15. In another aspect of the present invention, it is contemplated to provide a method for manufacturing a coated substrate according to the present invention. A material for forming an interface layer is produced by carbon ion collision of a first material forming a substrate surface of a tool to be coated without a metal layer, and an amorphous carbon film is directly attached to a second material by using a PVD process, where the PVD process includes cathode arc evaporation of a graphite target and application of a negative bias voltage to the substrate to be coated, and the absolute value of the bias voltage at the beginning of the deposition process of the amorphous carbon film 100 is higher than the absolute value of the bias voltage at the end of the deposition process of the amorphous carbon film, and the absolute value of the bias voltage is changed during the deposition of the amorphous carbon film. It is contemplated that the absolute value of the bias voltage changes stepwise. It is also contemplated that the absolute value change of the bias voltage is in the range from 0 V to 600 V, preferably in the range from 10 V to 500 V. It is further contemplated that the absolute value change of the arc current is in the range from 35 A to 80 A, preferably in the range from 40 A to 70 A. The amorphous carbon film can be deposited by maintaining the processing temperature in the range from 80 °C to 170 °C, preferably in the range from 100 °C to 140 °C. During the deposition process of the amorphous carbon film, it is contemplated to adjust the coating film parameters so as to reduce droplets in the amorphous carbon film.

[0038] To explain the present invention in more detail, several examples are described below, and the details are illustrated in FIGS. 1 to 10. The examples and illustrations should not be understood as limitations of the present invention.

Examples

[0039] Examples of Coating Film Adhesion According to the Present Invention A coating film made of hydrogen-free tetrahedral amorphous carbon was coated on a substrate.

[0040] Different types of substrates and materials were cleaned and introduced into a vacuum coating chamber, which is a coating site of types DOMINO SC and DOMINO L of Oerlikon.

[0041] In particular, the following substrates were coated and the following substrates were inspected and / or tested. 1) Quality reference specimens formed as follows a. Steel types: 90MnCrV8 and 1.2842 having a hardness higher than 62HRC, an arithmetic mean roughness Ra ≦ 0.05 μm, and dimensions of φ22 mm × 5.6 mm b. Cemented carbide SPGN 120308 6wt% Co, dimensions 12 mm × 12 mm, thickness: 3.18 mm, and 2) Cutting tools and forming tools of the following types a. Drills, mills, reamers, taps, punches, cutters, dies, molds, trimming b. Shoulder tools made of carbide, high-speed steel, D2 steel, H13 steel, and CuBe tools, etc.

[0042] Vacuum was generated in the vacuum coating chamber until a vacuum condition corresponding to a pressure of 0.08 Pa was achieved.

[0043] Thereafter, an argon gas flow in the range of 50 sccm to 300 sccm was used as a processing gas. Preferably, the argon flow was maintained at a value in the range of 150 sccm to 250 sccm. The argon gas flow was introduced into the vacuum coating chamber and the argon gas flow was changed during the process according to the adjusted processing pressure, that is, the process was performed at a controlled pressure.

[0044] The total processing pressure during the deposition of the amorphous carbon coating film was maintained at a pressure value in the range of 0.05 Pa to 1.5 Pa.

[0045] Formation of Carbon-Rich Interface (Interface Layer 10) By including an adhesive layer between the substrate surface and the coating film, without degrading the tool performance, in order to enhance the adhesion of the coating film to the substrate surface, prior to the deposition of the coating film, carbon ions that generate carbon implantation at the interface between the substrate surface to be coated and the coating film to be deposited on the substrate are collided with the substrate surface to be coated.

[0046] During the collision of the carbon ions, it was achieved that the carbon ions penetrate into the substrate surface to be coated to a depth in the range of 3 nm to 30 nm. Thus, a carbon-rich interface layer was fabricated and observed in the SEM images described below that clearly show carbon embedded in the substrate material (e.g., carbon embedded in a steel matrix).

[0047] After forming the interface layer, the processing parameters were adjusted to start the formation of the amorphous carbon film. In the case of forming the amorphous carbon film, the carbon from the graphite target was evaporated by using the cathodic arc ion plating method in an atmosphere containing argon gas as the only processing gas entering the vacuum coating chamber, with the graphite target used as the coating film raw material.

[0048] The inventors found that the absence of a metal intermediate layer (e.g., the absence of a Cr intermediate layer that is usually deposited to enhance the adhesion between the substrate and the coating film) significantly led to a substantial increase in the adhesion of the coating film to the substrate. The inventors can achieve this additional substantial increase due to the fact that no droplets are formed at the interface between the substrate surface to be coated and the coating film when the metal intermediate layer is not formed. Thus, it is presumed that the absence of droplets leads to an increase in adhesion. This is because during the deposition of the metal intermediate layer, droplets are generated together with the metal intermediate layer and the droplets adhere to the metal intermediate layer.

[0049] A coating film made of hydrogen-free tetrahedral amorphous carbon was deposited later by using the cathodic arc evaporation technique.

[0050] A more detailed description of the method used to coat the substrate in the above-described embodiments of the invention is as follows. After being cleaned, it was introduced into the interior of a vacuum coating chamber, and the above-described substrate was subjected to the following additional processing steps under vacuum.

[0051] Preheating The substrate was heated to a maximum of about 100 °C in the same vacuum coating chamber used for carbon implantation. For the preheating step, a radiant heater present in the vacuum coating chamber was used.

[0052] Etching The surface of the substrate to be coated was etched with argon ions. The etching was performed by the so-called "advanced energy glow discharge" (AEGD) technique. In the vacuum coating chamber, a titanium target was activated at the rear of the shutter by an arc having a target current of 80 A. The generated titanium ions were captured by the shutter. The electrons generated by this process were conducted by a positive potential applied to a rod in the chamber, and the surface of the substrate to be coated was etched. During this stage, an argon flow was supplied to the vacuum coating chamber, and the pressure was controlled at a pressure value of about 1 Pa. The argon ions (Ar+) thus generated were directed towards the surface of the substrate to be coated by applying a negative bias voltage to the substrate whose absolute value was in the range of 50 V to 200 V. Next, the etching of the surface of the substrate to be coated was thus performed by ion collision.

[0053] A more detailed specific example of the carbon ion collision step for forming the carbon-rich interface (interface layer 10) of the invention as already described above is Carbon doping of a steel or cemented carbide substrate is carried out by using an argon flow in the range of 50 sccm to 300 sccm (for example, about 250 sccm) at a processing pressure in the range of 0.01 Pa to 0.02 Pa (for example, about 0.015 Pa). Argon is introduced by a gas shower immediately in front of a carbon-containing target (for example, a graphite target). The carbon-containing target is ignited by a trigger wire and operated at a target current in the range of 40 A to 55 A (for example, 45 A). Next, the obtained carbon ions (C+) are accelerated on the substrate surface to be coated by applying a negative bias voltage in the range of absolute values in the range of 500 V to 700 V (for example, about 500 V). This resulted in a low implantation of carbon ions into the substrate under the substrate surface to be coated.

[0054] Adhesion of a carbon transition layer (transition layer 30) The absolute value of the negative bias voltage was decreased, for example, from 500 V to 250 V or to an even lower value.

[0055] Adhesion of an hydrogen-free tetrahedral amorphous carbon film (also called ta-C film or amorphous carbon film 100). The hydrogen-free tetrahedral amorphous carbon film (ta-C film) was generated at the same processing pressure used in the previous processing step by using an argon flow in the range of 50 sccm to 80 sccm (for example, between 60 sccm and 70 sccm). In this case, the carbon-containing target (for example, a graphite target) was operated at a higher target current (for example, in the range of 60 A to 90 A). The absolute value of the negative bias voltage was increased at a given rate (for example, an execution increment describing a slope, or stepwise (for example, in two steps forming two different layers (for example, lower layer 120 and upper layer 150))) over the total coating processing time (here meaning the total adhesion processing of amorphous carbon film 100) in the range from 10 V to 250 V or in the range from 10 V to 100 V or less.

[0056] The target current of the carbon-containing target was kept constant.

[0057] Applying a lower bias voltage at the beginning of the coating process had the advantage of producing a ta-C layer (e.g., the lower layer 120) with a lower hardness.

[0058] Subsequently, further increasing the absolute value of the bias voltage enabled the deposition of a ta-C layer (i.e., a harder ta-C layer, e.g., the upper layer 150) with a higher hardness, where the hardness measured by using a known nanoindentation method (e.g., the method using a Fischerscope nanoindentation device) was in the range of, for example, 50 GPa to 80 GPa.

[0059] By using a negative bias voltage of about -80 V and a substrate temperature close to 120 °C, a significant increase in the ratio of sp3 bonds and a simultaneous decrease in the ratio of sp2 bonds could be achieved. As a result, a very hard diamond-like upper layer with a hardness significantly higher than the rest of the coating film in the range of about 60 GPa to 80 GPa (i.e., in the range of 60 GPa to 80 GPa) was obtained. This upper layer with a significantly high hardness was found to provide significant advantages for cutting applications and shaping applications.

[0060] For the analysis of the properties of the coating film of the invention, various standard characterization tests or characterization techniques as follows were used, for example. Scanning electron microscopy (SEM) Nano scratching test for comparison of coating film adhesion properties Secondary ion mass spectrometry Transmission electron microscopy (TEM) Micro-Epsilon (Micro Epsilon) measurement of the internal stress of the coating film (by using the known calculation of the residual stress (also called internal stress) of a thin elongated piece in accordance with DIN Technical Report 30 {in German: DIN-Fachbericht 39}, see particularly page 163)

[0061] The residual stress values shown in Fig. 10 (in all these cases, residual compressive stress values) are values from the coatings of three different inventions, all having a multilayer structure as shown in Fig. 4a and a total coating thickness of 600 nm. The residual compressive stresses of the modified examples of the coatings of the three inventions are each -4.2 GPa, which is quite low compared to the residual compressive stress of a state-of-the-art comparative coating that does not have the structure of the present invention. For example, the residual compressive coating of a state-of-the-art coating having the structure shown in Fig. 1 and a total coating thickness of 400 nm has a residual compressive stress of -6.128 GPa, which is very high compared to the modified example of the present invention whose stress measurement value is shown in Fig. 10.

[0062] The present invention is suitable, for example, for attaching very thin films that enable precision tools and coatings of components for different applications as follows. Cutting tools having sharp blades and / or complex shapes, and forming tools such as dies that require ultra-high precision (e.g., those with unchanging shapes) Components or surfaces used in semiconductor applications

[0063] Furthermore, the present invention enables coatings on a very wide range of substrate materials (e.g., aluminum Al and Al alloys), copper-beryllium (Cu-Be and Cu-Be alloys), all steel types, all carbide types, and cermet alloys, etc.).

Claims

1. 1. A coated substrate, preferably a coated tool, comprising a coated surface for a manufacturing process (e.g., a machining or forming process), The coating surface is formed by a substrate surface made of a first material (1) and a coating system (preferably an arc PVD-deposited coating system) applied to the substrate surface, The coating system includes an amorphous carbon film (100), and the amorphous carbon film (100) has sp C—C bonds. ３ The bonding rate is sp ２ It is a tetrahedral hydrogen-free amorphous carbon film with a bonding rate exceeding the The amorphous carbon film (100) has the sp along the thickness of the amorphous carbon film. ２ The sp of the C-C bond relative to the ratio of bonding ratio ３ The amorphous carbon film (100) is designed to include various ratios of the bonding ratios, the ratio increasing (e.g., increasing continuously and / or stepwise) from the bottom to the top of the amorphous carbon film (100), the bottom being the region of the amorphous carbon film (100) closest to the substrate, and the top being the region of the amorphous carbon film (100) farthest from the substrate. characterized in that Coated substrate.

2. The amorphous carbon film (100) is formed as a multilayer film including at least two tetrahedral hydrogen-free amorphous carbon layers, the at least two layers being: an underlayer (120) including the region of the amorphous carbon film (100) closest to the substrate; and an upper layer (150) including the region of the amorphous carbon film (100) farthest from the substrate, ２ The sp of the C-C bond relative to the ratio of bonding ratio ３ an upper layer (150) in which the ratio of the bonding ratios is higher along the thickness of the upper layer (150) than along the thickness of the lower layer (120); 2. The coated substrate of claim 1.

3. The upper layer (150) is the outermost layer of the amorphous carbon film (100).

3. The coated substrate of claim 2.

4. The amorphous carbon film (100) is applied to the substrate surface in such a way that an interface layer (10) is formed between the first material (1) on the substrate surface and the amorphous carbon film (100); The interface layer (10) is made of a carbon-injected material, and the carbon-injected material is formed of a first material and carbon injected into the first material; The thickness of said interface layer (10) is at least 3 nm The coated substrate according to any one of claims 1 to 3, characterized in that it is

5. a transition layer (30) is deposited between the interface layer (10) and the amorphous carbon film (100); The transition layer (30) is a carbon layer that improves the interfacial transition between the interface layer (10) and the amorphous carbon film (100).

5. The coated substrate of claim 4.

6. The transition layer (30) is a tetrahedral hydrogen-free amorphous carbon layer.

6. The coated substrate of claim 5.

7. The amorphous carbon film (100) has a low residual compressive stress corresponding to an absolute value of 5.5 GPa or less, preferably in the range of 2.8 GPa to 5.5 GPa, more preferably in the range of 3 GPa to 5 GPa.

2. The coated substrate of claim 1.

8. The amorphous carbon film (100) includes at least a portion (e.g., layer) exhibiting both properties, wherein the ratio of the average Young's modulus of the amorphous carbon film to the average hardness of the amorphous carbon film measured in GPa by using standard nanoindentation techniques is in the range of 7 to 13, preferably in the range of 8 to 12.

2. The coated substrate of claim 1.

9. the underlayer (120) has a hardness in the range of 30 GPa to 50 GPa, preferably in the range of 30 GPa to 45 GPa; The upper layer (150) has a hardness in the range of 50 GPa to 80 GPa, preferably in the range of 55 GPa to 80 GPa, or in the range of 55 GPa to 75 GPa.

3. The coated substrate of claim 2.

10. the underlayer (120) has a Young's modulus in the range of 250 GPa to 350 GPa; The upper layer (150) has a Young's modulus in the range of 500 GPa to 800 GPa.

3. The coated substrate of claim 2.

11. The transition layer (30) a hardness in the range of 50 GPa to 80 GPa, preferably in the range of 55 GPa to 80 GPa or in the range of 55 GPa to 75 GPa, and / or Has a Young's modulus in the range of 500 GPa to 800 GPa 6. The coated substrate of claim 5.

12. the amorphous carbon film (100) exhibits multiple hues instead of a single color, e.g., has a rainbow appearance to the human eye in the presence of visible light; 2. The coated substrate of claim 1.

13. The amorphous carbon film (100) exhibits a monochromatic color, e.g., a black or gray appearance to the human eye in the presence of visible light.

2. The coated substrate of claim 1.

14. The amorphous carbon film (100) has the sp along the thickness of the entire amorphous carbon film (100). ２ The sp of the C-C bond relative to the ratio of bonding ratio ３ At least one layer containing the highest ratio of said bonding ratios 2. The coated substrate of claim 1.

15. The sp along the thickness of the entire amorphous carbon film (100) ２ The sp of the C-C bond relative to the ratio of bonding ratio ３ The at least one layer containing the highest proportion of the percentage of bonding is the top layer (150).

15. The coated substrate of claim 14.

16. the thickness of said interface layer (10) is in the range of 3 nm to 200 nm, preferably in the range of 3 nm to 100 nm, more preferably in the range between 3 nm and 50 nm; and / or The thickness of the transition layer (30) is in the range of 10 nm to 200 nm, preferably in the range of 15 nm to 100 nm, more preferably in the range of 15 nm to 70 nm.

5. The coated substrate of claim 4.

17. the thickness of said underlayer (120) is in the range of 30 nm to 2000 nm, preferably in the range of 30 nm to 500 nm, more preferably in the range of 50 nm to 300 nm; and / or The thickness of said upper layer (150) is in the range of 50 nm to 1000 nm, preferably in the range of 50 nm to 500 nm, more preferably in the range of 70 nm to 350 nm.

5. The coated substrate of claim 4.

18. The average hardness of the amorphous carbon film (100) is in the range between 50 GPa and 80 GPa, preferably in the range between 50 GPa and 70 GPa.

2. The coated substrate of claim 1.

19. The average Young's modulus of the amorphous carbon film (100) is in the range between 500 Gpa and 800 Gpa, preferably in the range between 600 Gpa and 750 Gpa.

2. The coated substrate of claim 1.

20. The amorphous carbon film exhibits a coefficient of friction, as measured by a ball-on-disk test, ranging between 0.05 and 0.

15.

2. The coated substrate of claim 1.

21. 10. A method for producing the coated substrate of claim 1, comprising the steps of: a processing step of providing a substrate having a surface made of a first material (1) to be coated; A process step of depositing an amorphous carbon film (100) by using a PVD process, the PVD process comprising cathodic arc evaporation of one or more graphite targets and application of a negative bias voltage to the substrate to be coated, in such a manner that the ratio of the proportion of sp3 bonding of C-C bonds to the proportion of sp2 bonding along the thickness of the amorphous carbon film has a minimum value at the beginning of deposition of the amorphous carbon film (100) and a minimum value at the end of deposition of the amorphous carbon film. a process step in which the absolute value of the bias voltage is varied during deposition of the amorphous carbon film (100) in such a way that the ratio of the proportion of sp3 bonding of the C-C bonds to the proportion of sp2 bonding along the thickness of the amorphous carbon film is varied, and the absolute value of the applied bias voltage at the beginning of the deposition process of the amorphous carbon film (100) is less than the absolute value of the applied bias voltage at the end of the deposition process of the amorphous carbon film (100); 1. A method for producing a coated substrate, comprising:

22. The absolute value of the bias voltage applied during deposition of the amorphous carbon film (100) is varied in the range of 0 V to 200 V, preferably in the range of 10 V to 180 V, more preferably in the range of 10 V to 150 V.

22. A method for producing a coated substrate according to claim 21.

23. During deposition of the amorphous carbon film (100), an arc current in the range of 50 A to 110 A is applied to the one or more graphite targets.

23. A method for producing a coated substrate according to claim 21 or 22, characterized in that

24. During deposition of the amorphous carbon film (100), at least a lower layer (120) and then an upper layer (150) are deposited, and the absolute value of the bias voltage used during deposition of the lower layer (120) is lower than the absolute value of the bias voltage used during deposition of the upper layer (150), preferably: For the deposition of the underlayer (120), a negative bias voltage with an absolute value ranging from 0 V to 50 V and an arc current ranging from 50 A to 110 A is used; and / or For the deposition of the upper layer (150), a negative bias voltage with an absolute value in the range of 50 V to 200 V, preferably in the range of 50 V to 180 V, more preferably in the range of 50 V to 150 V, and an arc current in the range of 50 A to 110 A are used.

23. A method for producing a coated substrate according to claim 21 or 22, characterized in that

25. Prior to the deposition of the amorphous carbon film (100), a process step of producing an interface layer (10) by bombarding the first material (1) with carbon ions generated from at least one carbon target (preferably the at least one carbon target is a graphite target), thus forming the carbon-infused material constituting the interface layer (10), preferably using a PVD process including an arc evaporation technique, applying an arc current preferably ranging from 30 A to 50 A, and using a bias voltage preferably ranging between 400 V and 1000 V to generate the carbon ions.

23. A method for producing a coated substrate according to claim 21 or 22, comprising:

26. a process step of producing a transition layer (30) by using a PVD process after the deposition of the interface layer (10) and before the deposition of the amorphous carbon film (100), the PVD process comprising cathodic arc evaporation of one or more graphite targets and the application of a negative bias voltage to the substrate to be coated, the absolute value of the bias voltage being varied during the deposition of the transition layer (30), preferably the absolute value of the applied bias voltage being reduced at the beginning of the deposition process of the transition layer (30) to an absolute value in the range of 150 V to 200 V, the same as the absolute value used to form the interface layer (10).

26. The method of claim 25, comprising:

27. The amorphous carbon film (100) is deposited by maintaining a processing temperature in the range of 70 to 180°C, preferably in the range of 80 to 170°C, and more preferably in the range of 100 to 140°C.

23. The method according to claim 21 or 22.

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