Coating, mold, and method for manufacturing the mold

Abstract

To provide a film capable of preventing damage from occurring even when machining a metal material, such as a titanium based material.SOLUTION: A film is formed on the surface of a metal member using tungsten and carbon as a main component. In the X-ray diffraction analysis of the film by a θ-2θ method using Cu-K α rays as an X-ray source, a first diffraction line having a peak within 33.3°-35.5° and a half value width within 0.5°-2.0°, a second diffraction line having a peak within 37.5°-41.5° and a half value width within 1.0°-4.0° and a third diffraction line having a peak within 72.5°-75.5° and a half value width 1.6°-5.0° are detected.SELECTED DRAWING: Figure 7

Description

Technical Field

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[0001] The present disclosure relates to a film, a mold, and a method for manufacturing a mold. <0000​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​To solve the above problems, a coating according to one aspect of this disclosure is a coating mainly composed of tungsten and carbon formed on the surface of a metal member, wherein in X-ray diffraction analysis of the coating using the θ-2θ method with Cu-Kα rays as the X-ray source, a first diffraction line is detected with a peak in the range of 33.3° to 35.5° and a full width at half maximum in the range of 0.5° to 2.0°, a second diffraction line is detected with a peak in the range of 37.5° to 41.5° and a full width at half maximum in the range of 1.0° to 4.0°, and a third diffraction line is detected with a peak in the range of 72.5° to 75.5° and a full width at half maximum in the range of 1.6° to 5.0°.

[0007] Furthermore, a mold relating to one aspect of this disclosure is a mold comprising a substrate and a film formed to cover the surface of the substrate, wherein in X-ray diffraction analysis of the film using the θ-2θ method with Cu-Kα rays as the X-ray source, the diffraction results obtained by X-ray diffraction show the detection of a first diffraction line with a peak in the range of 33.3° to 35.5°, a second diffraction line with a peak in the range of 37.5° to 41.5°, and a third diffraction line with a peak in the range of 72.5° to 75.5°.

[0008] Furthermore, a method for manufacturing a mold relating to one aspect of the present disclosure is a method for manufacturing the above-mentioned mold, wherein the substrate is held on a table in a vacuum chamber so as to face a cathode material made of tungsten carbide, a predetermined bias voltage is applied to the table, and a magnetic field is generated on the cathode material from a magnetic field generating unit located on the back side of the cathode material, and a predetermined current is passed through the cathode material to generate an arc discharge from the cathode material and form the film on the surface of the substrate. [Effects of the Invention]

[0009] According to one aspect of this disclosure, it is possible to provide a coating that can suppress damage even when processing metallic materials such as titanium-based materials. [Brief explanation of the drawing]

[0010] [Figure 1] This figure illustrates a coating and a mold using the coating according to an embodiment of the present disclosure. [Figure 2] This diagram illustrates the schematic configuration of the manufacturing apparatus used to form the above-mentioned coating. [Figure 3] This is a flowchart illustrating the manufacturing method of the above-mentioned coating. [Figure 4] This figure illustrates the state of the vicinity of the cathode material during the formation process shown in step S4 of Figure 3. [Figure 5] This diagram illustrates the direction of magnetic field lines on the surface of the cathode material. [Figure 6] This graph shows the results of X-ray diffraction analysis of the coating in Example 1. [Figure 7] This is an enlarged view showing the first, second, and third diffraction lines in the graph of Figure 6. [Figure 8] This graph shows the results of X-ray diffraction analysis of the coating in Example 2. [Figure 9] This is an enlarged view showing the first, second, and third diffraction lines in the graph of Figure 8. [Figure 10] This graph shows the results of X-ray diffraction analysis of the substrate. [Figure 11] This table shows the maximum diffraction intensity of each diffraction line in Example 1 and Example 2. [Figure 12] This table shows the ratio of the maximum intensity of each diffraction line to the maximum intensity of the second diffraction line in Examples 1 and 2. [Figure 13] This graph illustrates the ratio of the maximum intensity of each diffraction line to the maximum intensity of the second diffraction line in Examples 1 and 2. [Figure 14] This table shows the measured full width at half maximum (FWHM) for Example 1 and Example 2, and the calculated crystallite sizes for Example 1 and Example 2. [Figure 15] This table shows the upper and lower limits of the full width at half maximum (FWHM) as disclosed herein, and the calculated values ​​for each crystal size at the upper and lower limits. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to FIG. 1. FIG. 1 is a diagram for explaining films 12 and 22 according to an embodiment of the present disclosure and molds 1 and 2 using the films 12 and 22, respectively. In the following description, the case where the present disclosure is applied to molds 1 and 2 for performing press working on a work material S which is a metal material such as a titanium-based material or an iron-based material such as a steel plate will be exemplified and described. Further, in the following description, "N1 to N2" indicates that it is N1 or more and N2 or less.

[0012] <Molds 1 and 2> As shown in FIG. 1, the molds 1 and 2 of the present embodiment each include a base material 11, 12 and the films 12, 22 of the present disclosure. The base materials 11 and 12 are each constituted by using a metal member H (FIG. )such as high-speed steel or cemented carbide such as molybdenum-based high-speed tool steel (for example, SKH51). The films 12 and 22 each have tungsten and carbon as main components. Here, having tungsten and carbon as main components means that the weight percentage of tungsten is 90 wt% or more, the weight percentage of carbon is 2 wt% or more, and the weight percentage of each impurity such as nickel or cobalt other than tungsten and carbon is less than 1 wt%.

[0013] As shown in FIG. 1, for example, the mold 1 has a convex portion 1A, and the mold 2 has a concave portion 2A that fits into the convex portion 1A. The mold 1 is pushed down against the mold 2 by a press working machine (not shown) in the press direction indicated by the arrow P in FIG. 1 with the work material S disposed on the mold 2 so as to cover the concave portion 2A. As a result, press working is performed on the plate-shaped work material S shown by the dotted line in FIG. 1 to form a desired shape by the molds 1 and 2.

[0014] <Manufacturing method of films 12 and 22> Next, the manufacturing method of the films 12 and 22 of the present embodiment will be specifically described with reference to FIGS. 2 to 5. The films 12 and 22 are formed on the surfaces of the substrates 11 and 12 so as to cover at least a part of the surfaces of the substrates 11 and 12 by the manufacturing method of the present disclosure. FIG. 2 is a diagram for explaining the schematic configuration of the manufacturing apparatus 30 for forming the films 12 and 22. FIG. 3 is a flowchart for explaining the manufacturing method of the films 12 and 22. FIG. 4 is a diagram for explaining the state in the vicinity of the cathode material 10 in the forming step shown in step S4 of FIG. 3. FIG. 5 is a diagram for explaining the direction of magnetic field lines on the surface of the cathode material.

[0015] <Manufacturing Apparatus 30 and Manufacturing Process> First, the manufacturing apparatus 30 and manufacturing process of the films 12 and 22 of the present embodiment will be specifically described with reference to FIGS. 2 and 3.

[0016] As shown in FIG. 2, the manufacturing apparatus 30 includes a vacuum chamber 31, an arc evaporation source 32, and a vacuum exhaust device 33. Inside the vacuum chamber 31, a table St on which a metal member H is placed is provided. In the manufacturing apparatus 30, a bias power supply Sp is provided outside the vacuum chamber 31 and is configured to apply a predetermined DC bias voltage to the table St. Further, the vacuum chamber 31 is provided with a gas supply port 31a, and a predetermined processing gas such as argon gas is supplied into the vacuum chamber 31 as indicated by an arrow G1 in FIG. 2. Furthermore, in the vacuum chamber 31, the vacuum exhaust device 33 is configured to maintain the inside at a predetermined degree of vacuum by performing an exhaust operation of exhausting from the inside of the vacuum chamber 31 as indicated by an arrow G2 in FIG. 2.

[0017] The arc-type evaporation source 32 comprises a flange 32a, an insulating sealant 32b, and an arc power supply 32c. The flange 32a is made of, for example, a non-magnetic metal material and is capable of supporting the cathode material (arc evaporation source) 10, made of tungsten carbide (WC), by a fixing ring R inside the vacuum vessel 31. The flange 32a is hermetically attached to the side surface of the vacuum vessel 31 with the insulating sealant 32b interposed therebetween. Furthermore, the negative electrode of the arc power supply 32c is connected to the flange 32a, and a predetermined DC voltage is applied from the arc power supply 32c to the cathode material 10 as the cathode. The positive electrode of the arc power supply 32c and the vacuum vessel 31 are electrically grounded, as shown in Figure 2.

[0018] Furthermore, a permanent magnet Mg is placed on the back of the cathode material 10, and a predetermined current can be passed through the cathode material 10 from the arc power supply 32c while a magnetic field G (Figure 4) is generated from the permanent magnet Mg. This causes an arc discharge to occur between the surface of the cathode material 10 and the trigger electrode TE. The arc discharge ignites between the trigger electrode TE and the cathode material 10 and then persists between the inner wall surface of the vacuum container 31 (Figure 2) and the cathode material 10. A melted portion is created on the surface of the cathode material 10 due to the arc discharge, and then the melted portion evaporates, and as indicated by arrow K, the evaporated material is scattered toward the metal member H, forming a film on the surface of the metal member H. Details of the arrangement of the permanent magnet Mg will be described later.

[0019] In the film manufacturing method of this embodiment, the heating step (step S2), cleaning step (step S3), and forming step (step S4) of the process shown in Figure 3, excluding the washing step (step S1), are sequentially performed inside the vacuum container 31. In other words, the arc ion plating process, including the heating step, cleaning step, and forming step, can be carried out using the manufacturing apparatus 30. As the manufacturing apparatus 30, for example, the "iDS-mini" manufactured by ITF Corporation Japan can be used. Figure 2 illustrates the case in which the forming step shown in step S4 of the manufacturing process shown in Figure 3 is carried out using the manufacturing apparatus 30.

[0020] First, before the cleaning process, the metal member H may be prepared by removing rust and oxidized parts from its surface using a polishing machine or grinding machine (not shown). Next, in the cleaning process (step S1), the metal member H is immersed in a cleaning tank (not shown). The cleaning tank is filled with a predetermined cleaning solution, such as an organic solvent or an alkaline cleaning agent, to wash away inorganic and organic dirt adhering to the surface of the metal member H. The metal member H, now clean, is then dried outside the cleaning tank, and the cleaning process is completed.

[0021] Next, the metal member H is transferred into the vacuum container 31. Then, the manufacturing apparatus 30 first performs a heating process (step S2). Specifically, in order to perform the heating process, the metal member H is fixed to a table St inside the vacuum container 31 using a jig (not shown). Next, the vacuum exhaust device 33 evacuates the inside of the vacuum container 31 so that the pressure is, for example, 0.01 Pa or less. Then, inside the vacuum container 31, the heating process is performed by operating a heater (not shown) for 60 minutes or more so that the temperature of the metal member H reaches, for example, 400°C or higher.

[0022] Next, a cleaning process (step S3) is performed. When the pressure inside the vacuum vessel 31 is, for example, 0.01 Pa or less, argon gas is introduced into the vacuum vessel 31 at a pressure of 0.1 to 5 Pa through the gas supply port 31a. Then, a negative DC bias voltage, for example, 100 to 1000 V, is applied to the table St from the bias power supply Sp. As a result, plasma is generated inside the vacuum vessel 31 around the metal member H and the table St, and the surface of the metal member H is cleaned by ion bombardment, thus completing the cleaning process. In addition to this description, a pulsed bias voltage may also be applied.

[0023] Next, the forming process (step S4) is carried out. Specifically, in the manufacturing apparatus 30, a negative DC bias voltage, for example, 10 to 200V, is applied to the table St from the bias power supply Sp. Also, in the arc-type evaporation source 32, a current of, for example, 50 to 250A is passed through the cathode material 10 from the arc power supply 32c. At this time, as shown in Figure 4, a permanent magnet Mg, which serves as a magnetic field generating unit, is positioned at a predetermined angle on the back side of the cathode material 10.

[0024] As shown in Figure 4, the cathode material 10 is attached to a fixing ring R provided at the tip of the flange 32a (Figure 2) and supported by the flange 32a. The permanent magnet Mg is, for example, a cylindrical isotropic ferrite magnet with magnetic poles at both ends. Furthermore, multiple permanent magnets, for example 45, are arranged in a ring shape with the magnetic poles of each permanent magnet Mg facing the discharge surface 10a (Figure 5) of the cathode material 10 opposite the metal member H, so as to be directed 45° outward from the cathode material 10, generating a magnetic field G at the periphery of the cathode material 10. The magnetic field G is, for example, about 20 gauss.

[0025] In Figure 5, at each point on the discharge surface 10a, the direction toward the center of the cathode material 10 is defined as the central direction C1. Near the periphery of the discharge surface 10a, if the angle between the central direction C1 and the magnetic field line Y1 is θ1, then magnetic field lines Y1 are generated such that the angle θ1 is acute.

[0026] Furthermore, at the outermost periphery of the discharge surface 10a of the cathode material 10, if the angle between the central direction C1 and the magnetic field line Y2 is θ2, then magnetic field lines Y2 are generated such that the angle θ2 is approximately right-angle.

[0027] Furthermore, in the portion of the discharge surface 10a of the cathode material 10 that is close to the center C, if the angle between the central direction C1 and the magnetic field line Y3 is θ3, then magnetic field lines Y3 are generated such that the angle θ3 is acute.

[0028] Furthermore, in Figure 5, the direction perpendicular to the discharge surface 10a and extending from the inside to the outside of the cathode material 10 is defined as the substrate direction C2. On the outer circumferential surface 10b of the cathode material 10, if the angle between the substrate direction C2 and the magnetic field lines Y4 is angle θ3, then magnetic field lines Y4 are generated such that angle θ4 is acute.

[0029] As described above, when a magnetic field G is generated, magnetic field lines with an acute angle θ1 (e.g., magnetic field line Y1) are generated at each point near the outermost edge of the discharge surface 10a. Also, magnetic field lines with an acute angle θ3 (e.g., magnetic field line Y3) are generated at each point near the center of the discharge surface 10a. Furthermore, magnetic field lines with an obtuse angle greater than 90° with respect to the discharge surface 10a (e.g., magnetic field line Y4) are generated at each point on the outer peripheral surface 10b outside the discharge surface 10a. As a result, when a magnetic field G is generated, magnetic field lines are generated surrounding the discharge surface 10a.

[0030] When an arc discharge AK occurs between the discharge surface 10a of the cathode material 10 and the trigger electrode TE, the arc of the arc discharge AK is affected by these magnetic field lines near the outermost edge of the discharge surface 10a. Arc spots have the property of moving in the direction in which the magnetic field becomes acute. As a result, arc spots tend to remain within the range sandwiched between, for example, magnetic field lines Y1 and Y3, and are sequentially formed only on the discharge surface 10a, and not on the outer surface 10b. In other words, arc spots do not move to the outer surface 10b, but remain on the discharge surface 10a and are sequentially formed and moved over a wide area inside the discharge surface 10a.

[0031] As a result, at the discharge surface 10a of the cathode material 10, the arc spot of the arc discharge AK causes evaporation of the cathode material 10 to occur at the discharge surface 10a. This evaporation is then scattered and deposited on the surface of the metal member H, as shown by arrow K in Figure 4. As a result, the cathode material 10 can be utilized more efficiently, and the coatings 12 and 22 can be formed more efficiently.

[0032] Specifically, if the movement of the arc spot is slow, the arc spot melts deeply, and the melted cathode material 10 scatters as droplets. These are called droplets or macro-particles (hereinafter collectively referred to as "coarse particles"). When the scattered coarse particles are incorporated into the film growing on the workpiece (for example, the surface of a mold), it becomes a defect in the film, which is undesirable. For example, in the arc evaporation source disclosed in Japanese Patent No. 6074573, a method of moving a magnet on the back surface of the cathode so that the arc spot moves at high speed inside the discharge surface has been proposed. By doing so, the movement speed of the arc spot can be increased, the scattering of coarse particles can be reduced, and the incorporation of coarse particles into the growing film can be prevented.

[0033] Also, by using such an evaporation source, the size of the evaporated particles becomes fine and the ionization rate becomes high. The ionization rate generally refers to the number ratio of charged particles among the evaporated particles. Further, it is defined here that the smaller the evaporated particles, the higher the ionization rate. The high-speed movement of the arc spot makes the evaporated particles smaller, and as a result, the ionization rate becomes high. The evaporated matter with a high ionization rate is attracted to the substrate to which a bias voltage is applied, and the growing film grows while receiving a stronger ion impact.

[0034] As a result of these, in the present disclosure, films 12 and 22 with uniformly small crystallite sizes and large lattice strains can be formed on the surfaces of the metal members H (substrates 11 and 21).

[0035] <Results of X-ray diffraction analysis> The inventors of the present disclosure performed X-ray diffraction analysis on the surfaces of the molds 1 and 2 on which the films 12 and 22 were respectively formed. In this X-ray diffraction analysis, D8 DISCOVER manufactured by Bruker AXS was used as the X-ray diffractometer (XRD; X-Ray Diffraction). The measurement conditions are as follows. Scanning axis: 2θ-θ, X-ray source: Cu-Kα ray, Detector: 1-dimensional detector, Tube voltage: 40 kV, Tube current: 40mA, Step: 0.03° Cumulative time: 0.3 seconds (1 measurement per sample, approximately 20 minutes), and Scan range (2θ): 10°~120°

[0036] In the molds 1 and 2 of this embodiment, when the above-described X-ray diffraction analysis was performed on the coatings 12 and 22, all diffraction lines were detected: a first diffraction line with a peak in the range of 33.3° to 35.5°, a second diffraction line with a peak in the range of 37.5° to 41.5°, and a third diffraction line with a peak in the range of 72.5° to 75.5°. In particular, the peak of the third diffraction line was in the range of 73° to 75°. Thus, the coatings 12 and 22 were films having a structure containing crystallites with a specific composition and orientation, as defined by the inclusion of the above-described first to third diffraction lines in the X-ray diffraction analysis.

[0037] On the other hand, a film that does not contain the three diffraction lines of this embodiment, that is, a film consisting of only two or one of the above diffraction lines, corresponds to a case where growth in a specific crystal orientation is dominant. Growth in a specific orientation tends to result in larger crystallites, which deviates from the aim of this embodiment. A characteristic example of this embodiment is that the crystallites become smaller by involving growth in moderately random orientations.

[0038] Furthermore, the full width at half maximum (FMAX) of the first diffraction line was in the range of 0.5° to 2.0°, the FMAX of the second diffraction line was in the range of 1.0° to 4.0°, and the FMAX of the third diffraction line was in the range of 1.6° to 5.0°. Thus, the films 12 and 22 were composed of films with very broad FMAXs in each diffraction line and containing very small crystallites.

[0039] Here, we will specifically verify that the coatings 12 and 22 of this embodiment and the molds 1 and 2 using them are composed of moderately fine crystallites and possess robust properties. In X-ray diffraction, the full width at half maximum (FWHM) of the diffraction lines is known to have the following relationship with respect to crystallite size and lattice strain. That is, crystallite size is inversely proportional to FWHM. Also, lattice strain is generally known to be large in films produced as aggregates of small crystallites. In this embodiment, the values ​​within the FWHM range for each of the first to third diffraction lines are relatively large, as described above.

[0040] Therefore, in this embodiment, as will be described later, the crystallite size is small, and the lattice strain is large. Thus, in this embodiment, the coatings 12 and 22 consist of fine crystallites, and relatively large lattice strain is generated due to compressive residual stress inside the material, similar to prestressed concrete. For this reason, the coatings 12 and 22 in this embodiment are tough films that are less susceptible to damage accompanied by cleavage, which occurs in films composed of single crystals or large crystallites. Furthermore, when used as a surface protective film for molds 1 and 2, they can effectively exhibit excellent protective effects, i.e., abrasion resistance. In addition, unlike the conventional example described above, the coatings 12 and 22 can significantly reduce the possibility of titanium adhering to the surface due to a chemical reaction between the titanium contained in the titanium-based material and the coating. For this reason, molds 1 and 2 can be made suitable for processing metallic materials such as titanium-based materials.

[0041] Furthermore, in each of the first to third diffraction lines, if the full width at half maximum exceeds the upper limit of the corresponding range, the crystallite size becomes smaller. As a result, the film approaches a non-crystalline structure, i.e., amorphous, from an aggregate of small crystals. Such amorphous materials, as exemplified by glass, tend to develop cracks rapidly, and the toughness of the film is lost. On the other hand, in this embodiment, since the full width at half maximum is below the upper limit of the corresponding range in each of the first to third diffraction lines, a film with a moderately large crystallite size is formed, suppressing amorphous formation and ensuring toughness.

[0042] Furthermore, in each of the first to third diffraction lines, if the full width at half maximum falls below the lower limit of the corresponding range, the crystallite size becomes larger. As a result, the brittleness inherent in single crystals, i.e., the ease of cleavage, becomes more pronounced in the coating. On the other hand, in this embodiment, since the full width at half maximum is above the lower limit of the corresponding range in each of the first to third diffraction lines, it is possible to suppress the crystallite size from becoming excessively large and to suppress the appearance of ease of cleavage. Moreover, in this embodiment, having crystallites of an appropriate size in the coatings 12 and 22 also leads to the presence of an appropriate number of grain boundaries where crystallites are in contact with each other, and crack propagation is hindered by the grain boundaries, thereby improving the toughness of the coatings 12 and 22.

[0043] <Examples> The present disclosure will be described in more detail below based on examples. In the examples, Examples 1 and 2 were prepared as the disclosed products. However, the present disclosure is not limited to Examples 1 and 2. Comparative Examples 1 to 4 were also prepared below as comparative products.

[0044] (Example 1) A mold for Example 1 was created by forming a 1.5 μm thick film mainly composed of tungsten and carbon on a substrate made of SKH51 using the manufacturing method shown in Figure 3.

[0045] (Example 2) A mold for Example 1 was created by forming a 2.8 μm thick film, mainly composed of tungsten and carbon, on a substrate made of SKH51 using the manufacturing method shown in Figure 3.

[0046] (Results of X-ray diffraction analysis of Example 1) Figure 6 is a graph showing the results of X-ray diffraction analysis of the film of Example 1. Figure 7 is an enlarged view showing the first, second, and third diffraction lines in the graph of Figure 6.

[0047] As shown in Figure 6, in Example 1, for a diffraction angle 2θ, the first diffraction line K11, the second diffraction line K21, and the third diffraction line K31 were detected at 33.3°~35.5°, 37.5°~41.5°, and 72.5°~75.5°, respectively, as indicated by the reference numeral 701 in Figure 7.

[0048] In detail, as shown by reference numeral 701 in Figure 7, the first diffraction line K11 was found to have a peak in the range of 33.3° to 35.5°. The peak value of 314, which is the maximum intensity of this first diffraction line K11, was 33.95°. The measured half-width of this first diffraction line K11 was 0.73.

[0049] Furthermore, as shown by reference numeral 702 in Figure 7, it was found that the second diffraction line K21 has a peak in the range of 37.5° to 41.5°. The peak value of 3163, which is the maximum intensity of this second diffraction line K21, was 39.30°. The measured value of the full width at half maximum of this second diffraction line K21 was 1.56.

[0050] Furthermore, as shown by reference numeral 703 in Figure 7, it was found that the third diffraction line K31 has a peak in the range of 72.5° to 75.5°. The peak value of 679, which is the maximum intensity of this third diffraction line K31, was 74.01°. The measured half-width of this third diffraction line K31 was 1.72.

[0051] (Results of X-ray diffraction analysis of Example 2) Figure 8 is a graph showing the results of X-ray diffraction analysis of the film in Example 2. Figure 9 is an enlarged view of the first, second, and third diffraction lines in the graph of Figure 8.

[0052] As shown in Figure 8, in Example 2, similar to Example 1, the first diffraction line K12, the second diffraction line K22, and the third diffraction line K32 were detected at diffraction angles 2θ, i.e., peaks around 34°, 39°, and 74°, respectively.

[0053] In detail, as shown by reference numeral 901 in Figure 9, the first diffraction line K12 was found to have a peak in the range of 33.3° to 35.5°. The peak value of 1172, which is the maximum intensity of this first diffraction line K12, was 33.98°. The measured half-width of this first diffraction line K12 was 0.57.

[0054] Furthermore, as shown by reference numeral 902 in Figure 9, it was found that the second diffraction line K22 has a peak in the range of 37.5° to 41.5°. The peak value of 1478, which is the maximum intensity of this second diffraction line K22, was 39.05°. The measured full width at half maximum of this second diffraction line K22 was 1.25.

[0055] Furthermore, as shown by reference numeral 903 in Figure 9, it was found that the third diffraction line K32 has a peak in the range of 72.5° to 75.5°. The peak value of 1429, which is the maximum intensity of this third diffraction line K32, was 73.92°. The measured value of the full width at half maximum of this third diffraction line K32 was 1.70.

[0056] (Results of X-ray diffraction analysis of substrates 11 and 21) Figure 10 is a graph showing the results of X-ray diffraction analysis of the substrate.

[0057] As shown in Figure 10, the X-ray diffraction analysis of the substrate revealed that diffraction lines around a diffraction angle of 45° were strongly present. Therefore, the diffraction lines around 45° in Figures 6 and 8 were found to originate from the substrate. Furthermore, the first to third diffraction lines shown in Figures 6 and 8 were not detected from the substrate, confirming that these first to third diffraction lines originated from the film of this disclosure. Moreover, as is clear from Figure 10, Figures 6 and 8, it was confirmed that the influence of the substrate was evident in the X-ray diffraction analysis results in Example 1, which had a smaller film thickness compared to Example 2.

[0058] (Diffraction intensity results) Next, the diffraction intensity results for Examples 1 and 2 will be specifically explained using Figures 11 to 13. Figure 11 is a table showing the maximum diffraction intensity of each diffraction line in Examples 1 and 2. Figure 12 is a table showing the ratio of the maximum intensity of each diffraction line to the maximum intensity of the second diffraction line in Examples 1 and 2. Figure 13 is a graph illustrating the ratio of the maximum intensity of each diffraction line to the maximum intensity of the second diffraction line in Examples 1 and 2. Note that the maximum intensity of a diffraction line is also called the peak intensity of the diffraction line.

[0059] As shown in Figure 11, the diffraction intensities for Example 1 were 314, 3160, and 695 at the first diffraction line with a peak around 34°, the second diffraction line with a peak around 39°, and the third diffraction line with a peak around 74°, respectively. The diffraction intensities for Example 2 were 1172, 1478, and 1429 at the first diffraction line with a peak around 34°, the second diffraction line with a peak around 39°, and the third diffraction line with a peak around 74°, respectively.

[0060] In Examples 1 and 2, the relative intensities of the first and third diffraction lines with respect to the maximum intensity of the second diffraction line with a peak around 39° were as shown in Figures 12 and 13. Specifically, as shown by reference numeral 1501 in Figures 12 and 13, in Example 1, the relative intensities of the first and third diffraction lines with respect to the maximum intensity of the second diffraction line were 10% and 22%, respectively. Also, as shown by reference numeral 1502 in Figures 12 and 13, in Example 2, the relative intensities of the first and third diffraction lines with respect to the maximum intensity of the second diffraction line were 79% and 97%, respectively.

[0061] Thus, in this disclosure, it was confirmed that the ratio of the maximum intensity of the third diffraction line to the maximum intensity of the second diffraction line was 20% or more. In other words, in this disclosure, it was confirmed that the third diffraction line was significantly present.

[0062] (Full width at half maximum and crystallite size) Next, we will specifically describe Example 1, Example 2, and the full width at half maximum (FWHM) and crystallite size of this disclosure using Figures 14 and 15. Figure 14 is a table showing the measured FWHM values ​​and calculated crystallite sizes of Example 1 and Example 2. Figure 15 is a table showing the upper and lower limits of the FWHM and the calculated crystal sizes for each of the upper and lower limits of this disclosure.

[0063] In Examples 1 and 2, the measured values ​​of the full width at half maximum (FMAX) for the first, second, and third diffraction lines are shown in Figure 14. The crystallite size (nm) can be determined using the following equation (1).

[0064] L = Kλ / (βcosθ) ----(1)

[0065] Here, equation (1) above is the equation by P. Scherrer, and the crystallite size (crystallite diameter) L satisfies the relationship in equation (1) above when the peak broadening is expressed by 2θ (full width at half maximum, β), which corresponds to the point where the intensity is half. Also, in equation (1), K is a constant, and according to P. Scherrer, its value is 0.9. The value of λ is 1.5418 (angstroms).

[0066] In Examples 1 and 2, the crystallite sizes of the first, second, and third diffraction lines calculated using the above equation (1) were the values ​​shown in Figure 14.

[0067] Furthermore, in the films 12 and 22 of this disclosure, as described above, the upper and lower limits of the full width at half maximum (FWHM) for the first, second, and third diffraction lines are set to the values ​​shown in Figure 15. Using these upper and lower limits, the crystallite sizes for the first, second, and third diffraction lines were calculated, resulting in the calculated values ​​shown in Figure 15. In other words, it was demonstrated that the crystallite size of the films 12 and 22 of this disclosure ranges from a maximum of several tens of nm to a minimum of 2 nm. Thus, it was confirmed that the films 12 and 22 of this disclosure are films composed of extremely fine crystallites.

[0068] (Comparative Example 1) A mold for Comparative Example 1 was prepared by forming a 1.5 μm thick film mainly composed of tungsten and carbon on a substrate made of SKH51 using a manufacturing method that utilizes a conventional arc evaporation source (for example, the arc evaporation source described in Patent Document 1).

[0069] (Results of X-ray diffraction analysis of Comparative Example 1) In Comparative Example 1, diffraction lines H31, H32, and H33 were detected at peaks of 36.0°, 61.5°, and 73.0°, respectively. The measured full width at half maximum (FWHM) of diffraction line H31 was 4.2°, and its peak intensity was 4300. The measured FWHM of diffraction line H32 was 3.3°, and its peak intensity was 300. The measured FWHM of diffraction line H33 was 4.2°, and its peak intensity was 500.

[0070] (Comparison of this disclosure with Comparative Example 1) The present disclosure illustrated in Examples 1 and 2 was found to differ from Comparative Example 1 in terms of peak position and full width at half maximum. Specifically, Comparative Example 1 was found to have a significantly larger full width at half maximum than the present disclosure, and its peak position differed from that of the present disclosure. Furthermore, it was confirmed that while Comparative Example 1 had a relatively fine crystallite size, its film structure was coarse, resulting in inferior density and increased abrasion compared to the film of the present disclosure.

[0071] Furthermore, unlike the present disclosure, as in Comparative Example 1 described in Patent Document 1, when a film is formed using the cathode material without generating a magnetic field from a magnetic field generating unit positioned at a predetermined angle on the back side of the cathode material, coarse particles generated due to the slow movement speed of the arc spot, which occurred when using the conventional arc evaporation source described in Patent Document 1, were incorporated into the film. As a result, it was confirmed that in Comparative Example 1, the film structure was coarse and lacked density.

[0072] (Comparative Example 2) A mold for Comparative Example 2 was prepared by forming a tungsten and carbon-based film with a thickness of 1.5 μm on a substrate made of SKH51 using a sputtering method with a target made of tungsten carbide (WC) at a substrate temperature of 300°C or less.

[0073] (Results of X-ray diffraction analysis of Comparative Example 2) In Comparative Example 2, diffraction line H41 was detected at a peak of 36.0°. The measured full width at half maximum of diffraction line H41 was 4.0°, and the peak intensity was 1000.

[0074] (Comparison of this disclosure with Comparative Example 2) The present disclosure illustrated in Examples 1 and 2 was found to differ from Comparative Example 2 in peak position and full width at half maximum. Furthermore, while Comparative Example 2 had a relatively fine crystallite size, the film was nearly amorphous and was found to be more brittle and prone to wear compared to the film of the present disclosure.

[0075] (Comparative Example 3) A mold for Comparative Example 3 was prepared by sputtering a substrate made of SKH51 with a target made of tungsten carbide (WC) at a substrate temperature of 400°C, forming a film mainly composed of tungsten and carbon with a thickness of 1.5 μm.

[0076] (Results of X-ray diffraction analysis of Comparative Example 3) In Comparative Example 3, diffraction lines H51, H52, H53, and H54 were detected at peaks of 37.0°, 42.0°, 62.0°, and 74.0°, respectively. The measured full width at half maximum (FWHM) of diffraction line H51 was 2.5°, and its peak intensity was 5000. The measured FWHM of diffraction line H52 was 3.0°, and its peak intensity was 3000. The measured FWHM of diffraction line H53 was 3.3°, and its peak intensity was 2000. The measured FWHM of diffraction line H54 was 3.5°, and its peak intensity was 2500.

[0077] (Comparison of this disclosure with Comparative Example 3) The present disclosure illustrated in Examples 1 and 2 was found to differ from Comparative Example 3 in peak position and full width at half maximum. Furthermore, while Comparative Example 3 had a relatively fine crystallite size, the film was nearly amorphous and was found to be more brittle and prone to wear compared to the film of the present disclosure.

[0078] (Comparative Example 4) A mold for Comparative Example 4 was prepared by forming a 1.5 μm thick coating, mainly composed of tungsten and carbon, on a substrate made of SKH51 using a thermal spraying method with a powder containing approximately 12% by weight of cobalt (Co).

[0079] (Results of X-ray diffraction analysis of Comparative Example 4) In Comparative Example 4, diffraction lines H61, H62, H63, and H64 were detected at peaks of 31.5°, 35.6°, 48.3°, and 64.0°, respectively. The measured full width at half maximum (FWHM) of diffraction line H61 was 1.0°, and its peak intensity was 2000. The measured FWHM of diffraction line H62 was 1.3°, and its peak intensity was 5000. The measured FWHM of diffraction line H63 was 1.5°, and its peak intensity was 4000. The measured FWHM of diffraction line H64 was 2.0°, and its peak intensity was 1200.

[0080] (Comparison of this disclosure with Comparative Example 4) The present disclosure illustrated in Examples 1 and 2 was found to have different peak positions compared to Comparative Example 4. Furthermore, it was confirmed that Comparative Example 4 had a relatively large crystallite size and was more prone to burning compared to the film of the present disclosure.

[0081] 〔summary〕 To solve the above problems, the coating of the first aspect of this disclosure is a coating mainly composed of tungsten and carbon formed on the surface of a metal member, wherein in X-ray diffraction analysis of the coating using the θ-2θ method with Cu-Kα rays as the X-ray source, a first diffraction line is detected with a peak in the range of 33.3° to 35.5° and a full width at half maximum in the range of 0.5° to 2.0°, a second diffraction line is detected with a peak in the range of 37.5° to 41.5° and a full width at half maximum in the range of 1.0° to 4.0°, and a third diffraction line is detected with a peak in the range of 72.5° to 75.5° and a full width at half maximum in the range of 1.6° to 5.0°.

[0082] According to the above configuration, it is possible to provide a coating that can suppress damage even when processing metallic materials such as titanium-based materials. Specifically, the inventors of this disclosure have found that by configuring a coating mainly composed of tungsten and carbon such that all of the first, second, and third diffraction lines are detected as a result of the above-mentioned X-ray diffraction analysis, it is possible to form a tough coating consisting of appropriately fine crystallites. This disclosure was completed based on this finding, and even when the coating is in direct contact with a metallic material such as a titanium-based material and undergoes predetermined metal processing, it is possible to suppress the occurrence of damage such as cleavage and cracks in the coating.

[0083] In the second embodiment, the coating may have a third diffraction line peak in the range of 73.0° to 75.0° in the coating of the first embodiment.

[0084] According to the above configuration, by limiting the peak of the third diffraction line to a narrow range, it is possible to provide a coating that can more reliably suppress damage even when processing metallic materials such as titanium-based materials.

[0085] In the third embodiment, the coating may have a ratio of 20% or more of the maximum intensity of the third diffraction line to the maximum intensity of the second diffraction line in the coating of the first or second embodiment.

[0086] According to the above configuration, the relative intensity of the third diffraction line to the maximum intensity of the second diffraction line is set to 20% or more, so it is possible to provide a coating that can more reliably suppress damage even when processing metallic materials such as titanium-based materials.

[0087] A mold according to a fourth aspect of the present disclosure comprises a substrate and a film formed to cover the surface of the substrate, wherein X-ray diffraction analysis of the film using the θ-2θ method with Cu-Kα radiation as the X-ray source detects a first diffraction line with a peak in the range of 33.3° to 35.5°, a second diffraction line with a peak in the range of 37.5° to 41.5°, and a third diffraction line with a peak in the range of 72.5° to 75.5°.

[0088] According to the above configuration, it is possible to provide a mold that can suppress damage even when processing metallic materials such as titanium-based materials. Specifically, the inventors of this disclosure have found that in a mold comprising a base material and a coating formed to cover the surface of the base material, by configuring the mold so that any of the first, second, and third diffraction lines are detected as a result of the above-mentioned X-ray diffraction analysis of the coating, it is possible to construct a mold with a tough coating made of appropriately fine crystallites. This disclosure was completed based on this finding, and even when the mold is in direct contact with metallic materials such as titanium-based materials to perform predetermined metal processing, it is possible to suppress the occurrence of damage such as cleavage and cracks in the coating of the mold.

[0089] The mold of the fifth embodiment may be such that, in the mold of the fourth embodiment, the full width at half maximum of the first diffraction line is in the range of 0.5° to 2.0°, the full width at half maximum of the second diffraction line is in the range of 1.0° to 4.0°, and the full width at half maximum of the third diffraction line is in the range of 1.6° to 5.0°.

[0090] According to the above configuration, since the range of the full width at half maximum is defined for the first, second, and third diffraction lines, the crystallite size of the mold coating can be made appropriately fine, thereby reliably improving the toughness of the coating. As a result, even when the mold is in direct contact with a metal material such as titanium-based material to perform a predetermined metal processing, the occurrence of damage such as cleavage and cracks in the mold coating can be more reliably suppressed.

[0091] In the mold of the sixth embodiment, the ratio of the maximum intensity of the third diffraction line to the maximum intensity of the second diffraction line may be 20% or more in the mold of the fourth or fifth embodiment.

[0092] According to the above configuration, the relative intensity of the third diffraction line to the maximum intensity of the second diffraction line is set to 20% or more, so it is possible to provide a mold that can more reliably suppress damage even when processing metallic materials such as titanium-based materials.

[0093] The mold of the seventh embodiment may be subjected to a predetermined molding process on a titanium-based material in any of the molds of the fourth to sixth embodiments.

[0094] According to the above configuration, even when a predetermined molding process is performed on a titanium-based material, damage to the mold can be suppressed.

[0095] A mold manufacturing method relating to one aspect of the present disclosure is a mold manufacturing method for manufacturing the above-mentioned mold, wherein the substrate is held on a table in a vacuum chamber so as to face a cathode material made of tungsten carbide, a predetermined bias voltage is applied to the table, and a magnetic field is generated on the cathode material from a magnetic field generating unit located on the back side of the cathode material, and a predetermined current is passed through the cathode material to generate an arc discharge from the cathode material and form the above-mentioned film on the surface of the substrate.

[0096] According to the above configuration, a predetermined bias voltage is applied to the table on which the mold substrate is placed. Furthermore, an arc discharge is initiated by applying a predetermined current to a cathode material made of tungsten carbide, while a magnetic field is generated from a magnetic field generating unit placed on its back side. This makes it possible to deposit a film on the surface of the substrate in which the crystal lattice distortion of the film material is large, with a uniformly small crystallite size and a high ionization rate. As a result, it is possible to provide a mold that can suppress damage even when processing metallic materials such as titanium-based materials.

[0097] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of this disclosure. [Explanation of Symbols]

[0098] 1, 2 molds 11, 21, H base material 12, 22 coating K11, K12 First diffraction line K21, K22: Second diffraction line K31, K32: Third diffraction line 31 Vacuum container St Table 10 Cathode Materials Mg permanent magnet (magnetic field generating part) G magnetic field

Claims

1. A coating formed on the surface of a metal component, mainly composed of tungsten and carbon, In the X-ray diffraction analysis of the aforementioned film using the θ-2θ method with Cu-Kα radiation as the X-ray source, The first diffraction line has a peak in the range of 33.3° to 35.5° and a full width at half maximum in the range of 0.5° to 2.0°, A second diffraction line has a peak in the range of 37.5° to 41.5° and a full width at half maximum in the range of 1.0° to 4.0°, All of the third diffraction lines, with peaks in the range of 72.5° to 75.5° and full width at half maximum in the range of 1.6° to 5.0°, were detected. A coating in which the ratio of the maximum intensity of the third diffraction line to the maximum intensity of the second diffraction line is 20% or more.

2. The coating according to claim 1, wherein the peak of the third diffraction line is in the range of 73.0° to 75.0°.

3. Substrate and The substrate comprises a coating mainly composed of tungsten and carbon, formed to cover the surface of the substrate, In the X-ray diffraction analysis of the aforementioned film using the θ-2θ method with Cu-Kα radiation as the X-ray source, The first diffraction line has a peak in the range of 33.3° to 35.5° and a full width at half maximum in the range of 0.5° to 2.0°, A second diffraction line has a peak in the range of 37.5° to 41.5° and a full width at half maximum in the range of 1.0° to 4.0°, All of the third diffraction lines, with peaks in the range of 72.5° to 75.5° and full width at half maximum in the range of 1.6° to 5.0°, were detected. A mold in which the ratio of the maximum intensity of the third diffraction line to the maximum intensity of the second diffraction line is 20% or more.

4. The mold according to claim 3, wherein the peak of the third diffraction line is in the range of 73.0° to 75.0°.

5. A mold according to claim 3 or 4, which performs a predetermined molding process on a titanium-based material.

6. A base material and A mold comprising a film formed to cover the surface of the substrate, In the X-ray diffraction analysis of the aforementioned film using the θ-2θ method with Cu-Kα radiation as the X-ray source, The first diffraction line has a peak in the range of 33.3° to 35.5° and a full width at half maximum in the range of 0.5° to 2.0°, A second diffraction line has a peak in the range of 37.5° to 41.5° and a full width at half maximum in the range of 1.0° to 4.0°, A method for manufacturing a mold, which produces a mold in which any of the third diffraction lines, having a peak in the range of 72.5° to 75.5° and a full width at half maximum in the range of 1.6° to 5.0°, can be detected. The substrate is held on a table in a vacuum chamber so as to face a cathode material made of tungsten carbide, and a predetermined bias voltage is applied to the table, The method is characterized by generating a magnetic field from a magnetic field generating unit positioned on the back side of the cathode material, and then applying a predetermined current to the cathode material to generate an arc discharge from the cathode material, thereby forming the film on the surface of the substrate. A method for manufacturing a mold, wherein the magnetic field generating unit is configured such that, near the outer periphery of the discharge surface of the cathode material, the angle between a first direction toward the center of the cathode material, along the discharge surface, and magnetic field lines outside the cathode material is acute, and near the center of the discharge surface, the angle between a second direction opposite to the first direction toward the discharge surface and magnetic field lines outside the cathode material is acute.

7. The method for manufacturing a mold according to claim 6, wherein the ratio of the maximum intensity of the third diffraction line to the maximum intensity of the second diffraction line is 20% or more.

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