Coated part and coating tool with coated part

Abstract

The present invention aims to provide a coated part in which the adhesion between the substrate and the polycrystalline diamond film is high and high temperature conditions can be used as film-forming conditions for the polycrystalline diamond film. [Solution] A coated component comprising a substrate and a hard film having multiple layers formed on the surface of the substrate, wherein the hard film comprises a diamond layer made of polycrystalline diamond and 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 hardness lower than that of the diamond 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] There have been tools in which the surface of a substrate is coated with a polycrystalline diamond film (for example, Patent Document 1). Some of these tools have a base film containing a metal such as Ti or Cr formed between the substrate and the polycrystalline diamond film. Such a base film improves the adhesion between the substrate and the polycrystalline diamond, preventing the polycrystalline diamond from peeling or falling off, thereby contributing to a longer product life. [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, when a polycrystalline diamond film is formed on such an underlayer under high temperature conditions, for example by plasma CVD, the underlayer is oxidized by the oxygen component contained in the raw material gas, reducing adhesion, resulting in a problem in which the adhesion between the substrate and the polycrystalline diamond is not improved.

[0005] The present invention has been made to solve the above-mentioned problems, and its main objective is to provide a coated part that has high adhesion between the substrate and the polycrystalline diamond film and that allows the use of high temperature conditions for forming the polycrystalline diamond film. [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 hardness lower than that of the diamond layer.

[0007] In a coated part constructed in this way, the carbon layer formed between the substrate and the diamond layer is made of a carbon-based material that is compatible with crystalline diamond and maintains adhesion even when oxidized, resulting in strong adhesion between the substrate and the polycrystalline diamond film, and allowing the use of high temperature conditions for the polycrystalline diamond film deposition, which prevents the polycrystalline diamond from peeling or falling off and extends the product's lifespan. Furthermore, since a carbon layer having a lower hardness than the diamond layer is formed beneath the diamond layer, when this coated part is used as a tool or sliding part, external impacts applied to the diamond layer can be absorbed by the carbon layer, improving impact resistance.

[0008] The carbon layer is preferably made of a carbonaceous material having an amorphous structure, such as diamond-like carbon (DLC). Among such carbonaceous materials, those containing hydrogen are preferred, and so-called hydrogen-containing DLC ​​(aC:H or ta-C:H) with a hydrogen content of 5 at% or more 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. In addition, if hydrogen-containing DLC ​​is used, it is possible to form a carbon layer with a lower hardness than the diamond layer.

[0009] It is preferable that the carbon layer and the diamond 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, for example, a coated part whose outermost surface is covered with a nitride film or DLC.

[0011] Specifically, the hardness of the carbon layer is preferably 80% or less of the hardness of the diamond layer. The hardness of the carbon layer is preferably 40% or more of the hardness of the diamond layer. The hardness of the diamond layer is preferably 10 GPa or more and 90 GPa or less. The hardness of the carbon layer is preferably 8 GPa or more and 40 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, a base layer is formed between the surface of the substrate and the carbon layer, so even if the substrate is made of a material (e.g., an iron-based material) that does not adhere well to carbon-based materials, it is possible to stably form a carbon layer.

[0013] The sum of the thickness of the diamond layer and the thickness of the carbon layer is preferably 2.0 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 equal to or greater than 1 μm, and the thickness of the carbon layer is preferably equal to or greater than 1 μm and equal to or less than 2 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 in this manner, it is possible to provide a coated part in which the adhesion between the substrate and the polycrystalline diamond film is high and high temperature conditions can be used as film-forming conditions for the polycrystalline diamond film. [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, 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 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 carbon layer 3 made of a carbon-based material, and the third layer (upper layer) from the bottom is a diamond layer 4 made of polycrystalline diamond. In other words, the diamond layer 4 is formed on the outermost layer constituting the surface of the hard film C (corresponding to the friction portion), the base layer 2 is formed on the bottommost layer in contact with 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 2.0 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 are configured so that the hardness of the carbon layer 3 is lower than the hardness of the diamond layer 4. Specifically, the hardness of the carbon layer 3 is 80% or less of that of 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 a so-called hydrogen-containing DLC ​​having a hydrogen content of 5 at% or more, such as aC:H (Hydrogenated Amorphous Carbon). The carbon-based material of the carbon layer 3 may be another hydrogen-containing DLC, such as ta-C:H, or a hydrogen-free DLC, such as ta-C or aC.

[0030] The hardness of the carbon layer 3 is preferably 8 GPa or more.

[0031] In addition, in view of the difficulty of film formation, the hardness of the carbon layer 3 is preferably 40 GPa or less.

[0032] The carbon layer 3 covers the substrate 1 with a substantially constant thickness, which is set to 1 μm or more and 2 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 a polycrystalline diamond film made of polycrystalline diamond, and is laminated on the carbon layer 3 so as to cover the surface of the carbon layer 3. Here, "made up of" means that 50% or more of the material making up the diamond layer 4 is made up of the polycrystalline diamond.

[0034] The polycrystalline diamond film is made of so-called nano-polycrystalline diamond, which has a grain size of 1000 nm or less. From the viewpoint of manufacturing, the grain size of the nano-polycrystalline diamond is preferably 5 nm or more.

[0035] The hardness of the diamond layer 4 is preferably 10 GPa or more to ensure wear resistance and long life, and is preferably 90 GPa or less to prevent excessive aggressiveness toward the mating material.

[0036] The diamond layer 4 covers the substrate 1 with a substantially constant thickness, and the thickness of the diamond layer 4 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 2-2. Deposition of carbon layer 3 The carbon 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 to a vacuum and into which a gas is introduced, a gas supply mechanism that supplies gas to the vacuum chamber, an antenna disposed in the vacuum chamber, and a high-frequency power supply that applies high-frequency waves to the antenna to generate inductively coupled plasma in the vacuum chamber.

[0042] 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 source gas containing C and H is supplied into the vacuum chamber. Next, a high frequency current is applied to an antenna from a high frequency power supply, generating an inductive electric field in the vacuum chamber and generating inductively coupled plasma. Then, a-C:H is synthesized by a plasma CVD method using this inductively coupled plasma, and a carbon layer 3 is formed so as to cover the surface of the underlayer 2. Since no oxygen is added to the material gas and the film is formed at a low temperature, oxidation of the underlayer can be suppressed.

[0043] The carbon layer 3 may be formed by a PVD method such as arc ion plating, sputtering, or ionization deposition using a PVD apparatus.

[0044] 2-3. Deposition of diamond layer 4 The diamond layer 4 is formed by the plasma CVD method using the above-mentioned CVD apparatus. Specifically, in the plasma CVD apparatus, the substrate 1 having the underlayer 2 and carbon layer 3 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 the antenna from a 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. Polycrystalline diamond is then synthesized by the plasma CVD method using this inductively coupled plasma, and the diamond layer 4 is formed so as to cover the surface of the carbon layer 3.

[0045] 3.Effects As described above, in the coated part 100 of this embodiment, the diamond layer 4 covering the substrate 1 is formed on the carbon layer 3 made of DLC (a-C:H), which is compatible with polycrystalline diamond. In this case, even if the diamond layer 4 is formed under high temperature conditions by, for example, plasma CVD, the adhesive strength of the carbon layer 3 does not decrease, so that the adhesiveness between the substrate 1 and the diamond layer 4 can be ensured. Furthermore, since the carbon layer 3 having a lower hardness than the diamond layer 4 is formed under the diamond layer 4, when the coated part 100 is used as a tool or a sliding part, the carbon layer 3 can absorb the external impact applied to the diamond layer 4, improving the impact resistance.

[0046] Since the outermost layer of the hard film C is the diamond layer 4, the wear resistance of the coated component 100 can be improved compared to when the outermost layer is a nitride film or DLC.

[0047] Furthermore, since the diamond layer 4 is made of nanodiamonds with a grain size of 1000 nm or less, the strength of the hard film C can be maintained while the diamond layer 4 is made thin.

[0048] Furthermore, since the underlayer 2 is provided between the substrate 1 and the carbon layer 3, it becomes possible to stably form the carbon layer 3 on the substrate 1 made of a metal material.

[0049] <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.

[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 surface of the cemented carbide drill was ultrasonically cleaned using acetone.

[0052] 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℃

[0053] On the underlayer 2 formed on the surface of the carbide drill, a carbon layer 3 made of a-C:H was formed by the above-mentioned plasma CVD method. The film formation conditions were as follows: · Raw material gas: C2H2 20sccm, Dilution gas: Ar 50sccm Pressure: 1Pa ·Discharge current: 10~20A Bias voltage: -600V ·Temperature: 150℃ In the case of the CVD method, it is easy to make the carbon layer 3 contain hydrogen by using H2 gas.

[0054] Then, a diamond layer 4 was formed on the carbon layer 3 formed on the surface of the cemented carbide drill by the above-mentioned plasma CVD method under the following film forming conditions. Frequency of supplied high frequency power: 13.56MHz Power density of supplied high frequency power: 6W / cm 2 Raw material gas: H2 20sccm, CH4 1sccm, CO2 12sccm Dilution gas: Ar 132 sccm Pressure: 15Pa RF power: 3kW Bias voltage: 35V ·Temperature: 600℃

[0055] 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 carbon layer 3 was 80% or less of the hardness of the diamond layer 4. The hardness of the carbon layer 3 was 8 to 40 GPa, and the hardness of the diamond layer 4 was 10 to 90 GPa.

[0056] 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.

[0057] 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.

[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. 2, 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 hardness lower than that of 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 10 GPa or more and 90 GPa or less.

6. 2. The coated part according to claim 1, wherein the hardness of the carbon layer is 8 GPa or more and 40 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 1 μm or more and 2 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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