Coated part and coating tool with coated part

Abstract

To provide a coated part that has high wear resistance and is resistant to adhesion of mating materials. [Solution] A coated part comprising a substrate and a hard film having multiple layers formed on the surface of the substrate, wherein the hard film has a diamond layer made of the polycrystalline diamond and a carbon layer made of hydrogen-free DLC laminated on the diamond layer, and the hardness of the diamond layer is configured to be equal to or greater than the hardness of the carbon layer.

Description

[Technical Field]

[0001] The present invention relates to a coated part having a hard film formed on the surface thereof and a coated tool having the coated part. [Background technology]

[0002] BACKGROUND ART Conventionally, there are tools whose surfaces are coated with polycrystalline diamond films in order to increase wear resistance and extend product life (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2012-232898 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since polycrystalline diamond films have unevenness on their surfaces due to their polycrystalline nature, there is a problem that when a soft material such as aluminum is cut using a tool such as that described above, the soft material adheres to the unevenness, resulting in a deterioration in processing accuracy.

[0005] The present invention has been made to solve the above-mentioned problems, and its main object is to provide a coated part that is highly wear-resistant and to which mating materials are less likely to adhere. [Means for solving the problem]

[0006] That is, the coated part according to the present invention has the following features: A coated part comprising a substrate and a hard film having a plurality of layers formed on a surface of the substrate, The hard film is a diamond layer made of the polycrystalline diamond; a carbon layer made of a carbon-based material and laminated on the diamond layer, The diamond layer has a hardness equal to or greater than the hardness of the carbon layer.

[0007] In a coated part configured in this manner, a hard film is formed by laminating a carbon layer on top of a diamond layer, so that the lower diamond layer ensures high wear resistance and cutting performance when used as a cutting tool, while the upper carbon layer fills in any irregularities in the diamond layer to smooth the surface of the hard film, preventing adhesion of mating materials when used as a cutting tool, for example. Furthermore, by covering the diamond layer with the carbon layer, peeling or falling off of the diamond layer is prevented, thereby extending the life of the tool or the like.

[0008] The carbon layer is preferably made of a carbonaceous material having an amorphous structure, such as diamond-like carbon (DLC). DLC with low hydrogen content and high hardness is preferred, and so-called hydrogen-free DLC (ta-C) with a hydrogen content of less than 5 at% is particularly preferred. Because the carbon layer is amorphous and has no crystalline structure, it is possible to form a smooth hard film surface. In addition, DLC, which is formed by covalent bonds, has the property of being resistant to adhesion with metals, which are formed by metallic bonds, making it advantageous for preventing adhesion. Hydrogen-free DLC can ensure sufficient hardness when used in cutting tools and is resistant to adhesion with aluminum and other materials.

[0009] It is preferable that the diamond layer and the carbon layer are formed continuously from top to bottom. In this case, the carbon layer is formed directly on the diamond layer, improving stability during the formation of the carbon layer.

[0010] The carbon layer is preferably formed as the outermost layer of the hard film.

[0011] Specifically, the hardness of the diamond layer is preferably equal to or greater than (1.0 times or greater than) the hardness of the carbon layer. The hardness of the diamond layer is preferably 25 GPa or greater. The hardness of the carbon layer is preferably 25 GPa or greater and 50 GPa or less. Here, "equivalent" means that the hardness of the diamond layer is, for example, about ±10% of the hardness of the carbon layer.

[0012] The hard film preferably has an underlayer made of a metal material between the surface of the substrate and the diamond layer. With this configuration, a base layer is formed between the surface of the substrate and the diamond layer, so even if the substrate is made of a material that does not adhere well to diamond (e.g., an iron-based material), it is possible to stably form a diamond layer.

[0013] The sum of the thickness of the diamond layer and the thickness of the carbon layer is preferably 1.5 μm or more. In addition, the thickness of the diamond layer is preferably equal to or greater than the thickness of the carbon layer. Specifically, the thickness of the diamond layer is preferably 1 μm or more, and the thickness of the carbon layer is preferably 0.1 μm to 0.5 μm. With this configuration, the carbon layer can adequately prevent the diamond layer from falling off, and since the carbon layer is thin, the diamond layer can be used as a functional layer for cutting.

[0014] The grain size of the polycrystalline diamond constituting the diamond layer is preferably 5 nm or more and 1000 nm or less. By forming the diamond layer using so-called nano-polycrystalline diamond having such a small grain size, it is possible to maintain the strength of the diamond layer and ensure the required hardness even when the diamond layer is thin.

[0015] In order to increase the crystallinity of the diamond, in Raman spectroscopy analysis with 325 nm excitation, the diamond layer preferably has a diamond peak intensity around 1333 cm-1 that is 1.0 times or more, more preferably 3.0 times or more, of the G band peak intensity around 1550 cm-1.

[0016] A coated tool according to the present invention includes the coated part described above. In this case, the same effects as those of the coated parts described above can be obtained. [Effects of the Invention]

[0017] According to the present invention configured as described above, it is possible to provide a coated component that has high wear resistance and is resistant to adhesion of mating materials. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view showing a structure of a coated part according to an embodiment of the present invention; [Figure 2] FIG. 4 is a schematic diagram showing the structure of a coated component according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of a coated part according to the present invention will now be described with reference to the drawings, in which: Figure 1 is a schematic cross-sectional view of a coated part according to the present invention.

[0020] 1. Configuration The coated part 100 of this embodiment is used in, for example, metal cutting tools such as drills and end mills, and as shown in Fig. 1, has a substrate 1 and a hard film C formed on the surface of this substrate 1. The coated part 100 may also be used as a sliding part such as a gear or a bearing.

[0021] The substrate 1 is made of a metal material, for example, tool steel, but may also be made of other materials such as glass, ceramics, plastic, silicon, iron, titanium, copper, cemented carbide, other alloy materials, SiC, GaN, AlN, BN, diamond, etc.

[0022] The substrate 1 may be subjected to a surface treatment such as a scratching treatment or a seeding treatment. For example, the substrate may be immersed in alcohol together with diamond fine particles and subjected to ultrasonic treatment to form irregularities on the surface. Furthermore, if the substrate 1 is a cemented carbide, the substrate may be immersed in an acidic solution such as a nitric acid solution to remove Co from the substrate 1, or the surface of tungsten carbide (WC) particles may be treated with an alkaline solution such as diluted NaOH before the seeding treatment.

[0023] The hard film C is a thin film formed to cover at least a portion of the surface of the substrate 1 and has the function of improving the wear resistance, heat resistance, etc. of the substrate 1. For example, if the coated component 100 is a cutting tool, the hard film C is formed on the friction portion (e.g., cutting edge) that rubs against the workpiece (counterpart).

[0024] The hard film C has multiple layers, and here has at least three layers. The first layer (lower layer) from the bottom (surface of the substrate 1) is a base layer 2 made of a metal material, the second layer (middle layer) from the bottom is a diamond layer 3 made of polycrystalline diamond, and the third layer (upper layer) from the bottom is a carbon layer 4 made of a carbon-based material. In other words, the carbon layer 4 is formed on the outermost layer that makes up the surface of the hard film C (corresponding to the friction portion), the base layer 2 is formed on the bottommost layer that comes into contact with the substrate 1, and the diamond layer 3 is formed between these two layers. In order to ensure sufficient wear resistance and life, the thickness of the hard film C is preferably 1.1 μm or more.

[0025] In the present invention, the diamond layer 3 and the carbon layer 4 are formed continuously one above the other, and are configured so that the hardness of the diamond layer 3 is equal to or greater than the hardness of the carbon layer 4. Specifically, the hardness of the diamond layer 3 is 1.0 times or more that of the carbon layer 4. Each layer will be described in more detail below.

[0026] The underlayer 2 is formed between the substrate 1 and the diamond layer 3 (here, on the surface of the substrate 1) and is made of a metal material such as Ti or Cr. Here, "made up of" means that 90% or more of the material making up the underlayer 2 is made up of the metal material. The underlayer 2 is an intermediate film that is coated on the substrate 1 as a pretreatment for coating the substrate 1 with the diamond layer 3, which will be described later.

[0027] The thickness of the base layer 2 is preferably 0.5 μm or less. The thickness of the base layer 2 is preferably 0.1 μm or more. Note that the thickness refers to the maximum thickness, and in the case where the coated part 100 is a cutting tool, it is the maximum thickness at the cutting edge.

[0028] The diamond layer 3 is a polycrystalline diamond film made of polycrystalline diamond, and is laminated on the underlayer 2 so as to cover the surface of the underlayer 2. Here, "made up of" means that 50% or more of the material making up the diamond layer 3 is made up of the polycrystalline diamond.

[0029] The polycrystalline diamond film is composed of so-called nano-polycrystalline diamond with grain sizes of 1000 nm or less. From a manufacturing standpoint, the grain size of the nano-polycrystalline diamond is preferably 5 nm or more. Then, irregularities corresponding to the grain size of this nano-polycrystalline diamond are formed on the surface of the diamond layer 3.

[0030] The hardness of the diamond layer 3 is preferably 25 GPa or more to ensure wear resistance and long life.

[0031] The diamond layer 3 covers the substrate 1 with a substantially constant thickness, and the thickness of the diamond layer 3 here is configured to be 1 μm or more. Again, the thickness here is a maximum thickness, measured at the cutting edge if the coated part 100 is a cutting tool.

[0032] Furthermore, in order to increase the crystallinity of the diamond, in Raman spectroscopy analysis with 325 nm excitation, the diamond layer 3 preferably has a diamond peak intensity around 1333 cm-1 that is 0.10 times or more, more preferably 3 times or more, of the peak intensity of the G band around 1550 cm-1.

[0033] The carbon layer 4 is a carbon film made of a carbon-based material, and is laminated on the diamond layer 3 so as to cover the surface of the diamond layer 3. Here, "made up of" means that 50% or more of the material making up the carbon layer 4 is made up of the carbon-based material.

[0034] The carbon-based material used in this embodiment has an amorphous structure and is DLC (Diamond-Like Carbon) in this example. The DLC used is preferably a so-called hydrogen-free DLC, which has high hardness and a hydrogen content of less than 5 at %, such as tetrahedral amorphous carbon (ta-C). The carbon-based material of the carbon layer 4 may be aC, which is another hydrogen-free DLC, or ta-C:H or aC:H, which is a hydrogen-containing DLC.

[0035] The hardness of the carbon layer 4 is preferably 25 GPa or more.

[0036] In addition, in view of the difficulty of film formation, the hardness of the carbon layer 4 is preferably 50 GPa or less.

[0037] The carbon layer 4 covers the substrate 1 with a substantially constant thickness, which is set to 0.1 μm or more and 0.5 μm or less in this example. Note that the thickness here is also the maximum thickness, and if the coated part 100 is a cutting tool, it is measured at the cutting edge.

[0038] The density of the carbon layer 4 is 1.5 g / cm 3 More than 2.5g / cm 3 The following is preferred:

[0039] 2. Film formation method The following describes a film forming apparatus for forming the hard film C consisting of the above three layers and coating the substrate 1 with the hard film C, and a method for manufacturing the coated component 100. However, the film forming method for the hard film C and the method for manufacturing the coated component 100 described below are merely examples, and the present invention is not limited to these.

[0040] 2-1. Deposition of Underlayer 2 The underlayer 2 is formed by, for example, an arc ion plating method using a conventional PVD apparatus. The PVD apparatus here includes an evaporation source having a cathode electrode mainly composed of the material to be evaporated, and a vacuum chamber that houses the evaporation source and functions as an anode electrode. A vacuum arc discharge is generated between these electrodes to evaporate the cathode electrode material and deposit it on the substrate 1. Here, a cathode electrode containing Cr as a main component is used to form an underlayer 2 on a substrate 1.

[0041] The underlayer 2 may be formed by other PVD methods such as sputtering, ionization vapor deposition, or ion plating, or may be formed by CVD or the like.

[0042] 2-2. Deposition of diamond layer 3 The diamond layer 3 is formed by, for example, a plasma CVD method using a conventional plasma CVD apparatus. The plasma CVD apparatus here includes a vacuum chamber that is evacuated and into which gas is introduced, a gas supply mechanism that supplies gas to the vacuum chamber, an antenna disposed within the vacuum chamber, and a high-frequency power supply that applies high-frequency waves to the antenna to generate inductively coupled plasma within the vacuum chamber.

[0043] In such a plasma CVD apparatus, a substrate 1 having the underlayer 2 formed on its surface is placed in a vacuum chamber, and a raw material gas containing C, H, and O is supplied into the vacuum chamber. Next, a high frequency is applied to an antenna from a high frequency power supply, causing a high frequency current to flow through the antenna, generating an inductive electric field within the vacuum chamber and generating inductively coupled plasma. Polycrystalline diamond is then synthesized by a plasma CVD method using this inductively coupled plasma, and a diamond layer 3 is formed to cover the surface of the underlayer 2.

[0044] 2-3. Deposition of carbon layer 4 The carbon layer 4 is formed by the arc ion plating method using the above-mentioned PVD apparatus. Here, a cathode electrode mainly composed of graphite is used to synthesize ta-C on the diamond layer 3 that covers the substrate 1, and the carbon layer 4 is formed so as to cover the surface of the diamond layer 3.

[0045] The carbon layer 4 may be formed by other PVD methods such as sputtering and ionization deposition, or may be formed by CVD or the like.

[0046] 3.Effects In this way, the coated part 100 of this embodiment is configured such that the diamond layer 3 that coats the substrate 1 is further coated with the carbon layer 4 made of DLC (ta-C) that is compatible with polycrystalline diamond. In this case, high wear resistance is ensured by the highly hard diamond layer 3, and the irregularities of this diamond layer 3 are filled in by the carbon layer 4, smoothing the surface of the hard film C, so that adhesion of the mating material can be prevented when used as, for example, a cutting tool. Preventing adhesion of the mating material improves processing accuracy and also reduces the cost required to remove the adhered mating material.

[0047] In addition, because it is made of ta-C with an amorphous structure, the outermost layer (friction area) of the hard film can be made flat. In addition, ta-C, which is made up of covalent bonds, has the property of being less likely to adhere to metals that are made up of metallic bonds, making it advantageous for preventing adhesion.

[0048] Furthermore, by covering with the carbon layer 4, the diamond layer 3 is prevented from peeling off or falling off, and therefore the life of the tool or the like can be extended. Since the outermost layer (sliding surface) of the hard film C is the carbon layer 4, it is possible to reduce the aggressiveness to the mating material compared to when the outermost layer is made of polycrystalline diamond.

[0049] Furthermore, since the diamond layer 3 is made of nanodiamonds with a grain size of 1000 nm or less, the diamond layer 3 can be thinned while maintaining the strength of the hard film C and ensuring the required hardness.

[0050] Furthermore, since the underlayer 2 is provided between the substrate 1 and the diamond layer 3, it becomes possible to stably form the diamond layer 3 on the substrate 1 made of a metal material.

[0051] <Example> The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples, and modifications can be made within the scope of the above and below-described aims, and all such modifications are within the technical scope of the present invention.

[0052] As the sample substrate 1, a carbide drill mainly made of SCM415 that had been subjected to Co removal processing was used.

[0053] In the example, first, the surface of the cemented carbide drill was ultrasonically cleaned using acetone.

[0054] Next, the underlayer 2 was formed on the surface of the cleaned carbide drill by the arc ion plating method described above under the following film forming conditions. ·Raw material: Cr Gas used: Ar 0.2 Pa Voltage condition: Bias -1000V ·Input power: 300W ·Temperature conditions: 100℃

[0055] On the underlayer 2 formed on the surface of the cemented carbide drill, a diamond layer 3 was formed by the above-mentioned plasma CVD method under the following film formation conditions. Frequency of supplied high frequency power: 13.56MHz Power density of supplied high frequency power: 6W / cm 2 Raw material gas: H220sccm, CH43sccm, CO28sccm Dilution gas: Ar 124sccm Pressure: 15Pa RF power: 3kW Bias voltage: 35V ·Temperature: 500℃

[0056] Then, a carbon layer 4 made of ta-C was formed on the diamond layer 3 formed on the surface of the cemented carbide drill by the above-mentioned arc ion plating method. The film formation conditions were as follows. Raw material: graphite target Gas used: Ar 100cc / min Voltage conditions: bias - 100V, arc current 40A ·Temperature conditions: 100℃ By forming the carbon layer under such relatively low temperature conditions, graphitization of the DLC forming this carbon layer can be avoided.

[0057] When the hardness of the sample formed under the above conditions was measured using a nanoindenter XP manufactured by MTS Corporation, the hardness of the diamond layer 3 was 80% or less of the hardness of the carbon layer 4. The hardness of the diamond layer 3 was 25 GPa or more, and the hardness of the carbon layer 4 was 25 to 50 GPa.

[0058] The crystallinity of the diamond layer of the sample formed under the above conditions was evaluated by laser Raman spectroscopy (325 nm excitation). Laser Raman instrument: LabRAM HR Evolution (HR-MT / ORS-TypeIII) / HORIBA Measurement conditions: Objective lens x40 (NUV) Neutral density filter 50% Confocal Hole 100 Grating 2400 (330 nm) 1333nm obtained for the sample ―1 Diamond peak intensity and m near 1550cm -1 The ratio of the G-band peak intensity to the diamond peak intensity (diamond / G-band (Raman)) was 1.0 or more. This confirmed that a diamond layer with high diamond crystallinity could be synthesized.

[0059] TEM observation of the carbon and diamond layers of the sample formed under the above conditions revealed that the carbon layer was amorphous, confirming the formation of DLC, and that diamond spots or ring-shaped diffraction gratings were observed in the diamond layer, confirming the formation of diamond crystals.

[0060] <Other embodiments> The coated part of the present invention is not limited to the above-described embodiment.

[0061] In the above embodiment, the hard film is composed of three layers, but the number of layers constituting the hard film is not limited to this. The hard film may have at least a carbon layer and a diamond layer formed directly on the carbon layer.

[0062] For example, as shown in Fig. 2, the hard film may have only two layers: a diamond layer 3 formed directly on the surface of the substrate 1, and a carbon layer 4 formed directly on the diamond layer 3. Even without providing an underlayer in this way, if the substrate 1 is a wafer or the like that has good adhesion to the diamond layer 3, a hard film C can be formed with high adhesion.

[0063] Although the diamond layer in the above embodiment is formed as the outermost layer of the coated part, a layer made of other material may be formed on the diamond layer, or an intermediate layer different from the above-mentioned base layer may be formed under the carbon layer.

[0064] It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, it will be understood by those skilled in the art that the above-described exemplary embodiments are specific examples of the following aspects. [Explanation of symbols]

[0065] 100···Coated parts 1...Base material C...dural membrane 2...base layer 3 Diamond layer 4 Carbon layer

Claims

1. A coated part comprising a substrate and a hard film having a plurality of layers formed on a surface of the substrate, The hard film is a diamond layer composed of polycrystalline diamond; a carbon layer made of hydrogen-free DLC laminated on the diamond layer, The coated component, wherein the diamond layer has a hardness equal to or greater than the hardness of the carbon layer.

2. The coated part according to claim 1 , wherein the hydrogen-free DLC contains less than 5 at % hydrogen.

3. 2. The coated part according to claim 1, wherein the diamond layer and the carbon layer are formed continuously one above the other.

4. 2. The coated part according to claim 1, wherein the carbon layer is formed as an outermost layer of the hard film.

5. 2. The coated part according to claim 1, wherein the diamond layer has a hardness of 20 GPa or more and 40 GPa or less.

6. 2. The coated part according to claim 1, wherein the hardness of the carbon layer is 25 GPa or more and 50 GPa or less.

7. 2. The coated part according to claim 1, wherein the hard film has an underlayer made of a metal material between the surface of the substrate and the diamond layer.

8. 2. The coated part according to claim 1, wherein the diamond layer has a thickness equal to or greater than the thickness of the carbon layer.

9. 2. The coated part according to claim 1, wherein the diamond layer has a thickness of 1 μm or more.

10. 2. The coated part according to claim 1, wherein the carbon layer has a thickness of 0.1 μm or more and 0.5 μm or less.

11. The diamond layer exhibited a Raman spectrum of 1333 nm in Raman spectroscopy with excitation at 325 nm. ―１ The peak intensity of diamond near m1550 cm －１ 2. The coated part according to claim 1, wherein the peak intensity of the G band is at least 1.0 times the peak intensity of the G band in the vicinity of the G band.

12. 2. The coated part according to claim 1, wherein the grain size of the polycrystalline diamond constituting the diamond layer is 5 nm or more and 1000 nm or less.

13. A coating tool comprising a coated part according to any one of claims 1 to 12.

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