Coated component and bearing with coated component

Abstract

To provide a coated part that has high abrasion resistance and low attack on mating materials. [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 has a diamond layer made of the polycrystalline diamond and a carbon layer made of hydrogen-containing DLC ​​laminated on the diamond layer, and the hardness of the diamond layer is configured to be higher than the hardness of the carbon layer.

Description

[Technical Field]

[0001] The present invention relates to a coated component having a hard film formed on its surface and a bearing including the coated component. [Background technology]

[0002] Conventional sliding parts include those whose surfaces are coated with polycrystalline diamond films to improve wear resistance and extend product life (see, 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, polycrystalline diamond films have high hardness and, because they are polycrystalline, have uneven surfaces, so when they are used to coat the surfaces of sliding parts, they become more aggressive to the mating material.

[0005] The present invention has been made to solve the above-mentioned problems, and its main object is to provide a coated part that has high wear resistance and low attack on mating materials. [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 higher hardness than 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 hard diamond layer, so that the lower diamond layer ensures high wear resistance, while the upper carbon layer fills in any irregularities in the diamond layer to smooth the surface of the hard film, making it less aggressive to mating materials when used as a sliding part or tool than when a diamond layer is formed on the surface. Furthermore, by covering the diamond layer with a carbon layer, peeling or falling off of the diamond layer is prevented, thereby extending the life of the sliding parts and tools.

[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 does not have a crystalline structure and can form a smooth surface on top of the diamond layer, it is possible to fill in the irregularities in the diamond layer and smooth the surface of the hard film.In addition, if hydrogen-containing DLC ​​is used, it is possible to form a carbon layer that is less hard than the diamond layer and less aggressive to the mating material.

[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 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. Furthermore, 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 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 2 μm or more. Specifically, the thickness of the diamond layer is preferably 1 μm or more and 2 μm or less, and the thickness of the carbon layer is preferably 1 μm or more and 2 μm or less. Here, the diamond layer and the carbon layer are formed to have approximately the same thickness. "Similar" means, for example, that the thickness of the carbon layer is about ±10% of the thickness of the underlying diamond layer. This configuration ensures that the carbon layer is thick enough to blend in with the diamond layer, and also ensures overall hardness because the carbon layer is not too thick relative to the diamond layer.

[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 bearing according to the present invention includes the above-described coated component. 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 part that has high wear resistance and is less aggressive to 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 1, the coated part 100 of this embodiment has a substrate 1 and a hard film C formed on the surface of this substrate 1. More specifically, the coated part 100 here is, for example, a rolling element of a bearing, and the hard film C is formed on the sliding surface (or friction portion) on the surface of the rolling element that slides against a raceway. The coated part 100 may be a raceway or another sliding part such as a gear. The coated part 100 may also be a tool part such as a drill or end mill that moves while contacting a workpiece. In other words, the coated part 100 may be any part that has a friction part that rubs against another object and has a hard film C formed on the friction part.

[0021] The substrate 1 is made of a metal material, for example, high carbon chromium bearing steel, but may also be made of other materials such as glass, ceramics, plastic, silicon, iron, titanium, copper, stainless steel, 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 so as to cover at least a part of the surface of the substrate 1 and has the function of improving the wear resistance, heat resistance, etc. of the substrate 1.

[0024] The hard film C has multiple layers, and in this case, it has at least three layers. The first layer (lower layer) from the bottom (surface of the substrate 1) is an underlayer 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 (the sliding surface of the rolling element), the underlayer 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 2.0 μm or more.

[0025] In the present invention, the diamond layer 3 and the carbon layer 4 are formed continuously from top to bottom, and are configured so that the hardness of the diamond layer 3 is higher than the hardness of the carbon layer 4. Specifically, the hardness of the carbon layer 4 is 80% or less of that of the diamond layer 3. 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 underlayer 2 is preferably 0.5 μm or less, and more preferably 0.1 μm or more. Note that the thickness refers to the maximum thickness.

[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 10 GPa or more to ensure wear resistance and a long life. The hardness of the diamond layer 3 is also preferably 90 GPa or less to prevent excessive aggressiveness toward the mating material. Within this range, sufficient hardness can be ensured for use as a sliding component.

[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. The thickness here is also the maximum thickness.

[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-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 4 may be another hydrogen-containing DLC, such as ta-C:H, or a hydrogen-free DLC, such as ta-C or aC.

[0035] The hardness of the carbon layer 4 is preferably 8 GPa or more.

[0036] In addition, in view of the difficulty of film formation, the hardness of the carbon layer 4 is preferably 40 GPa or less.

[0037] The carbon layer 4 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.

[0038] The density of the carbon layer 4 is 1.5 g / cm 3 More than 2.5g / cm 3 The following is preferable: This allows the formation of a coating suitable for coating the surface of a sliding part.

[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 plasma CVD method using the CVD apparatus described above. Specifically, in the plasma CVD apparatus, the substrate 1 having the underlayer 2 and diamond layer 3 formed on its surface is placed in a vacuum chamber, and a raw material gas containing C and H 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 induced electric field in the vacuum chamber and generating inductively coupled plasma. Then, a-C:H is synthesized by the plasma CVD method using this inductively coupled plasma, 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 CVD methods such as thermal CVD, or by PVD methods such as arc ion plating, sputtering, and ionization deposition using a PVD apparatus.

[0046] 3.Effects In this way, the coated part 100 of this embodiment is configured such that the diamond layer 3 covering the substrate 1 is further coated with the carbon layer 4 made of DLC (a-C:H) which is compatible with polycrystalline diamond. In this case, high wear resistance is ensured by the diamond layer 3 having high hardness, and the irregularities of this diamond layer 3 are filled in by the carbon layer 4, making the surface of the hard film C smooth, thereby reducing the aggressiveness to mating materials when used as a sliding part or tool. 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 sliding part or tool can be extended.

[0047] Furthermore, by removing the excess carbon layer 4 that fills in the irregularities in the diamond layer 3 caused by polishing or wear during use, the outermost layer of the hard film C can be made into an intermediate layer where polycrystalline diamond and a-C:H are mixed together. This makes it possible to achieve both high wear resistance and low aggressiveness at the outermost surface of the hard film C.

[0048] 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, the raceway, 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 rolling element of a bearing whose main component is high carbon chromium bearing steel was used.

[0053] In the example, first, the surface of the rolling element was ultrasonically cleaned using acetone.

[0054] Next, the underlayer 2 was formed on the surface of the cleaned rolling element 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 conditions: 100℃

[0055] On the underlayer 2 formed on the surface of the rolling element, 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: H2 20sccm, CH4 1sccm, CO2 12sccm Dilution gas: Ar 132 sccm Pressure: 15Pa RF power: 3kW Bias voltage: 35V ·Temperature: 600℃

[0056] Then, a carbon layer 4 made of a-C:H was formed on the diamond layer 3 formed on the surface of the rolling element by the plasma CVD method described above. 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 4 contain hydrogen by using H2 gas.

[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 carbon layer 4 was 80% or less of the hardness of the diamond layer 3. The hardness of the diamond layer 3 was 10 to 90 GPa, and the hardness of the carbon layer 4 was 8 to 40 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 x 40 (NUV) Neutral density filter 50% Confocal Hall 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 C 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, the 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 made of the polycrystalline diamond; a carbon layer formed on the diamond layer and composed of hydrogen-containing DLC; The coated component, wherein the diamond layer has a hardness greater than the hardness of the carbon layer.

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

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

4. 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.

5. 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.

6. 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.

7. 2. The coated part according to claim 1, wherein the thickness of the carbon layer is approximately the same as the thickness of the diamond layer.

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

9. 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.

10. 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.

11. 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.

12. A bearing comprising a coated component according to any one of claims 1 to 11.

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