Coating part and coating tool including coating part

Abstract

To provide a coating part with a high-durability diamond film when used, the diamond film with a high-adhesion being stably deposited in production.SOLUTION: A coating part includes a base material, and a hard film that is formed on a surface of the base material and has multiple layers. The hard film is constituted so as to have a diamond layer constituted of polycrystalline diamond, and a carbon layer that is formed between the surface of the base material and the diamond layer, constituted of a carbon-based material, and has a hardness higher than that of the diamond layer.SELECTED DRAWING: Figure 1

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] Conventionally, there are tools in which a polycrystalline diamond film is coated on the surface of a substrate (for example, Patent Document 1). In the process of manufacturing such tools, in order to stably form a polycrystalline diamond film, an underlayer (for example, a metal film containing Ti or Cr) is sometimes formed on the surface of the substrate to improve adhesion between the substrate and the polycrystalline diamond. [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, if a polycrystalline diamond film is formed on an underlayer that is less hard than diamond, such as a metal film containing Ti or Cr, the polycrystalline diamond film will become distorted when used as a tool, resulting in the problem that the diamond film will be more likely to peel off.

[0005] The present invention has been made to solve the above-mentioned problems, and its main objective is to provide a coated part that can be coated with a diamond film with high adhesion and stability during manufacturing, and that has a diamond film that is highly durable during use. [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 composed of polycrystalline diamond; The carbon layer is a layer formed between the surface of the substrate and the diamond layer, and is made of a carbon-based material and has a higher hardness than the diamond layer.

[0007] In a coated part constructed in this way, the diamond layer is formed on a carbon layer made of a carbon-based material that is compatible with diamond, so the diamond layer can be formed stably with high adhesion during the manufacturing process. Furthermore, because a carbon layer with a higher hardness than the diamond layer is formed below the diamond layer, when the coated part is used as a tool or sliding part, the diamond layer is less likely to be distorted and peeled off, improving durability. Furthermore, since a diamond layer made of polycrystalline diamond, which has a rougher surface than DLC and is more aggressive to mating materials, can be formed as the outermost layer, cutting performance can be improved.

[0008] The carbon layer is preferably made of a carbonaceous material having an amorphous structure, such as diamond-like carbon (DLC). DLC with a low hydrogen content and high hardness is preferred, and so-called hydrogen-free DLC (ta-C) with a hydrogen content of 5% or less is particularly preferred. By forming a carbon layer made of a carbon-based material with an amorphous structure that has better adhesion than diamond as a layer below the diamond layer, it is possible to improve adhesion between the hard film and the substrate. Furthermore, with DLC, it is possible to form a carbon layer that is harder than the diamond layer.

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

[0010] The diamond layer is preferably formed as the outermost layer of the hard film. This allows for improved wear resistance compared to coated parts whose outermost surface is covered with a nitride film or DLC.

[0011] Specifically, the hardness of the diamond layer is preferably 80% or less of the hardness of the carbon layer, the hardness of the diamond layer is preferably 20 GPa or more and 40 GPa or less, and the hardness of the carbon layer is preferably 25 GPa or more and 50 GPa or less.

[0012] The hard film preferably has an underlayer made of a metal material between the surface of the substrate and the carbon layer. With this configuration, because the underlayer is formed between the surface of the substrate and the carbon layer, it is possible to stably form the carbon layer even if the substrate is made of a material that does not adhere well to carbon-based materials (for example, an iron-based material). Also, because the carbon layer, which is harder than the underlayer and diamond layer, is provided between the underlayer and diamond layer, when this coated part is used as a tool or sliding part, the diamond layer is less likely to be distorted and peeled off, improving durability.

[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, even when the present invention is applied to a substrate that is prone to wear, such as a drill, the hard film can have sufficient wear resistance and life.

[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, the strength of the diamond layer can be maintained even if the diamond layer is made 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 form a diamond film with high adhesion and stability during manufacturing, and to provide a coated part in which the diamond film has high durability during use. [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. 2 is a diagram showing the manufacturing conditions of each sample in the examples. [Figure 3] 1 is a diagram summarizing the thickness of the hard film of each sample produced in the examples. [Figure 4] 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, plastic, silicon, iron, titanium, copper, metals such as cemented carbide, other alloy materials, SiC, GaN, AlN, BN, diamond, etc. The substrate 1 here is a cemented carbide drill.

[0022] The substrate 1 may be subjected to a surface treatment such as a scratching treatment or a seeding treatment. For example, if the substrate 1 is a cemented carbide alloy, the substrate 1 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, followed by the above-mentioned seeding treatment. Furthermore, if the substrate 1 is silicon, the substrate 1 may be immersed in alcohol together with diamond microparticles and subjected to a scratching treatment or a seeding treatment in which irregularities are formed on the surface by ultrasonic 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 cutting edge.

[0024] The hard film C has multiple layers, and here has at least three layers. The first layer from the bottom (lower layer) is a base layer 2 made of a metal material, the second layer from the bottom (middle layer) is a carbon layer 3 made of a carbon-based material, and the third layer from the bottom (upper layer) is a diamond layer 4 made of polycrystalline diamond. In other words, the diamond layer 4 is formed on the outermost layer that forms the surface of the hard film C, the base layer 2 is formed on the bottom layer that contacts the substrate 1, and the carbon 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 1.5 μm or more.

[0025] In the present invention, the carbon layer 3 and the diamond layer 4 are formed continuously from top to bottom, and the carbon layer 3 is configured to have a higher hardness than the diamond layer 4. Each layer will be described in more detail below.

[0026] The underlayer 2 is formed between the substrate 1 and the carbon 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 carbon layer 3, which will be described later.

[0027] The thickness of the underlayer 2 is preferably 0.5 μm or less, and more preferably 0.1 μm or more. The thickness means 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 carbon layer 3 is formed between the substrate 1 and the diamond layer 4 (here, on the underlayer 2), and is a carbon film made of a carbon-based material. Here, "made of" means that 50% or more of the material making up the carbon layer 3 is made of the carbon-based material.

[0029] 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 so-called hydrogen-free DLC (ta-C: Tetrahedral Amorphous Carbon), which has high hardness and a hydrogen content of 5% or less. The carbon-based material of the carbon layer 3 may also contain hydrogen (ta-C:H, aC:H, etc.).

[0030] Since the hardness of the diamond layer is 20 to 40 GPa, in order to ensure that the hardness of the underlying carbon layer is sufficient, the hardness of the carbon layer 3 is preferably 25 GPa or more.

[0031] In addition, in view of the difficulty of film formation, the hardness of the carbon layer 3 is preferably 50 GPa or less.

[0032] The carbon layer 3 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.

[0033] The diamond layer 4 is formed on the carbon layer 3 and is a polycrystalline diamond film made of polycrystalline diamond. The polycrystalline diamond film here is made of so-called nano-polycrystalline diamond with grain sizes of 5 nm to 1000 nm. From a manufacturing standpoint, the grain size of the nano-polycrystalline diamond is preferably 5 nm or more.

[0034] The hardness of the diamond layer 4 is preferably 20 GPa or more to ensure wear resistance and long life, and is preferably 40 GPa or less to prevent excessive aggressiveness toward the mating material.

[0035] The diamond layer 4 covers the substrate 1 with a substantially constant thickness, which is preferably equal to or greater than the thickness of the carbon layer. The thickness of the diamond layer here is set to 1 μm or greater. The thickness here is also the maximum thickness, measured at the cutting edge if the coated part 100 is a cutting tool.

[0036] Furthermore, in order to increase the crystallinity of the diamond, in Raman spectroscopy analysis with 325 nm excitation, the diamond layer 4 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 2-2. Deposition of carbon layer 3 The carbon layer 3 is also formed by the arc ion plating method using the above-mentioned PVD apparatus. Here, the underlayer 2 is formed on the substrate 1 using a cathode electrode containing graphite as its main component.

[0041] The carbon layer 3 may be formed by other PVD methods such as sputtering and ionization deposition, or may be formed by CVD or the like.

[0042] 2-3. Deposition of diamond layer 4 The diamond layer 4 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 placed inside the vacuum chamber, and a high-frequency power supply that applies high-frequency waves to the antenna to generate inductively coupled plasma inside the vacuum chamber.

[0043] In such a plasma CVD apparatus, a component having the base layer 2 formed on the surface of the substrate 1 is placed in a vacuum chamber, and a source gas containing C, H, and O is supplied into the vacuum chamber. Next, a high frequency is applied to the antenna from the high frequency power supply, causing a high frequency current to flow through the antenna, generating an inductive electric field in the vacuum chamber and generating inductively coupled plasma. A diamond layer 4 is then synthesized by plasma CVD using this inductively coupled plasma, and the component is coated with the diamond layer 4.

[0044] 3.Effects As described above, in the coated part 100 of this embodiment, the diamond layer 4 that coats the substrate 1 is formed on the carbon layer 3 that has a higher hardness than the diamond layer 4. In this case, the diamond layer 4 is formed on the carbon layer 3 made of DLC, which is compatible with diamond, so the diamond layer 4 can be formed stably with high adhesion during the manufacturing process. Furthermore, because the carbon layer 3, which has a higher hardness than the diamond layer 4, is formed below the diamond layer 4, when the coated part 100 is used as a tool or sliding part, the diamond layer 4 is less likely to be distorted and peeled off, improving durability.

[0045] Since the substrate 1 is coated with the diamond layer 4, the wear resistance of the substrate 1 can be improved compared to a substrate 1 coated with a nitride film or DLC.

[0046] Furthermore, since the diamond layer 4 is made of nanodiamonds with a grain size of 5 nm to 1000 nm, the hard film C can be made thin while maintaining its strength.

[0047] Furthermore, because the underlayer 2 is provided between the substrate 1 and the carbon layer 3, it is possible to stably form the carbon layer 3 on the substrate 1 made of a metal material. Furthermore, because the carbon layer 3, which is harder than the underlayer 2 and the diamond layer 4, is provided between these two layers, when the coated component 100 is used as a tool or sliding component, the diamond layer 4 is less likely to be distorted and peeled off, improving durability.

[0048] <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.

[0049] In this example, three sample substrates 1 (No. 1 to No. 3) were prepared, and for each sample substrate 1, the underlayer 2 and carbon layer 3 were formed under the same conditions, and the diamond layer 4 was formed under mutually different conditions.

[0050] As the sample substrate 1, a carbide drill mainly made of SCM415 that had been subjected to Co removal processing was used.

[0051] In the example, first, the surfaces of the plurality of cemented carbide drills were ultrasonically cleaned using acetone.

[0052] Next, the underlayer 2 was formed on the surface of each cleaned cemented carbide drill by the arc ion plating method described above. The film formation conditions were as follows. ·Raw material: Cr Gas used: Ar 0.2 Pa Voltage condition: Bias -1000V ·Input power: 300W ·Temperature condition: 100℃

[0053] On the underlayer 2 formed on the surface of each cemented carbide drill, a carbon layer 3 was further formed by the arc ion plating method described above. The film formation conditions were as follows. Raw material: graphite target Gas used: Ar 100cc / min Voltage conditions: bias - 100V, arc current 40A ·Temperature condition 100℃ By forming the carbon layer under such relatively low temperature conditions, graphitization of the DLC forming this carbon layer can be avoided.

[0054] Then, a diamond layer 4 was formed on the carbon layer 3 formed on the surface of each cemented carbide drill by the plasma CVD method described above. For three sample substrates 1 (No. 1 to No. 3), diamond layers 4 were formed by changing the raw material gas composition, substrate temperature, and Ar gas flow rate ratio. The raw material gas flow rate, raw material gas composition, Ar gas flow rate ratio, substrate temperature, and vacuum chamber pressure during film formation for each sample are as shown in Figure 2. Other film formation conditions were as follows: Frequency of supplied high frequency power: 13.56MHz Power density of supplied high frequency power: 6W / cm2

[0055] The hardness of each sample formed under the above conditions was measured using a Nanoindenter XP manufactured by MTS Corp. The measured hardness of each sample is shown in Figure 2.

[0056] The crystallinity of each 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 x 40 (NUV) Neutral density filter 50% Confocal Hall 100 Grating 2400 (330 nm) The 1333nm obtained for each sample ―1 Diamond peak intensity and m near 1550cm -1 The ratio of the peak intensity of the G band to that of the nearby G band (diamond / G band (Raman)) is shown in FIG. The diamond / G band ratio of all samples was 1.0 or more, and in particular, samples No. 1 and No. 2 had a ratio of 3 or more, confirming that a diamond layer with high diamond crystallinity could be synthesized.

[0057] The thickness of the hard film C of each sample formed under the above conditions was measured by observing the cross section using a scanning electron microscope. The measured thickness of the hard film C of each sample is shown in FIG.

[0058] <Other embodiments> The coated part of the present invention is not limited to the above-described embodiment.

[0059] 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.

[0060] For example, as shown in Fig. 4, the hard film may have only two layers: a carbon layer 3 formed directly on the surface of the substrate 1, and a diamond layer 4 formed directly on the carbon layer 3. Even without providing an underlayer in this way, if the substrate 1 has good adhesion to the carbon layer 3, such as a wafer, a hard film C can be formed with high adhesion.

[0061] 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.

[0062] 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]

[0063] 100···Coated parts 1...Base material C...dural membrane 2...base layer 3 Carbon layer 4 Diamond 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 formed between the surface of the substrate and the diamond layer, the carbon layer being made of a carbon-based material and having a higher hardness than the diamond layer.

2. 2. The coated part according to claim 1, wherein the carbon layer is made of a carbon-based material having an amorphous structure.

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 diamond layer is formed as the 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 carbon 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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