Diamond coating

Abstract

Provided is a diamond-coated body comprising: a substrate that is formed from a material having a larger thermal expansion coefficient than diamond and that has a surface region extending in a first direction and a second direction which are mutually intersecting; a plurality of grooves in the surface region of the substrate, the grooves extending in the first direction and being spaced from each other in the second direction; and a coating layer that includes diamond as a constituting material and that covers the surface region of the substrate and the grooves; and a low density section which is formed on the bottom portion of each of the grooves and for which the density of diamond is lower than that of the coating layer.

Description

Technical Field

[0006] ,

[0001] The present invention relates to a diamond-coated body having a diamond coating layer formed on the surface of a base material.

Background Art

[0002] Conventionally, a diamond-coated body having a diamond coating layer formed on the surface of a base material has been used for a member that requires wear resistance like a tool.

[0003] In this type of diamond-coated body, when the base material is made of a material having a larger coefficient of thermal expansion than diamond, the coating layer may be easily peeled off due to the influence of stress generated during the formation process of the coating layer. Therefore, in recent years, a technique has been proposed to improve the adhesion between the base material and the coating layer by coating the surface region with diamond together with the groove portion formed on the base material side (see Patent Document 1).

Prior Art Documents

Patent Documents

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[0007] To solve the above problems, the first phase is a diamond coating comprising: a substrate made of a material having a larger coefficient of thermal expansion than diamond, and having surface regions extending along a first direction and a second direction that intersect with each other; a plurality of grooves formed in the surface region of the substrate, extending along the first direction and spaced apart in the second direction; a coating layer made of diamond, covering the surface region of the substrate together with each of the grooves; and a low-density portion formed on the inner side of each of the grooves, where the density of diamond is lower than that of the coating layer.

[0008] Furthermore, in this situation, the second position shown below may also be adopted. In the second phase, the low-density portion is formed as a void where no diamond exists.

[0009] Furthermore, in each of the above situations, the third situation shown below may also be adopted. In the third phase, the low-density portion occupies 10% to 80% of the area of ​​the groove portion in a cross-sectional view along a direction intersecting the first direction.

[0010] Furthermore, in each of the above situations, the fourth situation shown below may also be adopted. In the fourth phase, the coating layer is a layer formed by vapor phase growth, and the groove portion has a groove width w corresponding to the distance between the contact points with the surface region of the substrate in each of the two virtual circles, each having a diameter equal to the thickness t of the coating layer, when viewed in cross-section along a direction intersecting the first direction, and positioned so as to be in contact with the groove portion along the axis along which the groove portion extends. The groove width w is defined by the formula [w≦t+t×cosθ] based on the angle θ formed between the virtual line from the contact point with the surface region of the substrate to the center in each virtual circle and the second direction.

[0011] Furthermore, in each of the above situations, the fifth situation shown below may also be adopted. In the fifth phase, the base material is made of cemented carbide and is used in a tool having a rake face and a flank face, and the groove and the coating layer are formed on the surface region that becomes the rake face. [Effects of the Invention]

[0012] Each of the diamond-coated surfaces described above has a low-density area at the back of each groove, where the diamond density is lower than that of the coating layer. This low-density area is more susceptible to contraction from surrounding pressure than the area formed within the groove in the coating layer. Therefore, even if residual stress is generated around the groove, this contraction can alleviate the residual stress. This prevents damage to the area formed within the groove in the coating layer due to residual stress around the groove, thus preventing the coating layer from peeling off. [Brief explanation of the drawing]

[0013] [Figure 1] Perspective view of a diamond-coated body in one embodiment of the present disclosure [Figure 2] Front view of a diamond-coated body in one embodiment of the present disclosure. [Figure 3] Perspective view of a substrate in one embodiment of the present disclosure [Figure 4] Front cross-sectional view of a groove in one embodiment of the present disclosure [Figure 5] Front cross-sectional view of a groove in another embodiment of the present disclosure [Figure 6] A front cross-sectional view showing the contraction of a low-density area in one embodiment of the present disclosure. [Modes for carrying out the invention]

[0014] Embodiments for carrying out the present invention will be described in detail with reference to the drawings. (1) Overall structure As shown in FIGS. 1 and 2, the diamond coating 1 includes a substrate 10 made of a material having a coefficient of thermal expansion greater than that of diamond, a plurality of groove portions 20 formed in the surface region of the substrate 10 respectively, a coating layer 30 covering the surface region of the substrate 10 together with each of the groove portions 20, and a low-density portion 40 formed on the back side of each of the groove portions 20.

[0015] The substrate 10 has a surface region extending along the first direction and the second direction intersecting each other. In the present embodiment, as shown in FIG. 3, the substrate 10 is used as a tool having a relief surface 11 and a rake surface 13, and this rake surface 13 forms a surface region extending along the first direction and the second direction. Further, the substrate 10 in the present embodiment is made of cemented carbide as a material.

[0016] The groove portions 20 each extend along the first direction on the rake surface 13 of the substrate 10 and are formed at intervals in the second direction. In the present embodiment, the groove portions 20 are formed as grooves extending straight in the third direction intersecting the rake surface 13.

[0017] More specifically, the groove portions 20 each having a width of 1 to 50 μm (preferably 2 to 20 μm) and a depth of 4 to 100 μm (preferably 5 to 50 μm) are formed at intervals of 4 to 200 μm (preferably 10 to 100 μm) (the distance between the axes in the groove portions 20). The groove portions 20 are formed such that the aspect ratio (= depth / width) of the depth and the width is 1.2 or more.

[0018] Also, in the present embodiment, the groove portions 20 are formed by scanning a femtosecond laser with a predetermined output along the surface of the substrate 10.

[0019] Further, as shown in FIG. 4, in a cross-sectional view along a direction intersecting the first direction, when two virtual circles C each having the film thickness t of the coating layer 30 as the diameter are arranged in a positional relationship sandwiching the groove portion 20 and in contact with the axis s along which the groove portion 20 extends, the groove width w corresponds to the distance (t+(t / 2)cosθ+(t / 2)cosθ=t+t·cosθ) between the contact points p1 of the substrate 10 with the virtual circle C and the scooping surface 13.

[0020] Specifically, the groove width w is within a range defined by the mathematical formula [w≦t+t·cosθ] based on the angle θ formed between the virtual line extending from the contact point p1 of the substrate 10 with the virtual circle C to the center p2 and the axis extending in the second direction in the virtual circle C.

[0021] The coating layer 30 is made of diamond as a material and covers the scooping surface 13 of the substrate 10 together with each of the groove portions 20. This coating layer 30 is formed so as to fill the groove portions 20 to a predetermined depth. In the present embodiment, the coating layer 30 is formed with a film thickness of 1 to 50 μm (preferably 30 μm or less).

[0022] The low-density portion 40 is formed as a region having a lower diamond density than the coating layer 30 on the back side of each of the groove portions 20. In the present embodiment, the low-density portion 40 is formed as a void in which diamond does not exist.

[0023] Further, the low-density portion 40 occupies 10% to 80% (preferably 20% to 70%) of the area of the groove portion 20 in a cross-sectional view along a direction intersecting the first direction.

[0024] In the diamond-coated body 1 described above, the coating layer 30 is a layer of diamond formed on the surface area of ​​the substrate 10 by a vapor phase growth method (specifically, microwave plasma CVD or thermal filament CVD) after applying diamond particles to the surface area of ​​the substrate 10. In this embodiment, prior to the formation of the coating layer 30, a predetermined surface treatment such as etching is performed on the surface area of ​​the substrate 10 in which the grooves 20 are formed. The coating layer 30 then fills the grooves 20 in the process of reaching a predetermined film thickness t. At this time, because the grooves 20 have the groove width w described above, the coating layer 30 fills the grooves 20 before it can completely fill the inside of the grooves 20, resulting in the formation of a low-density area 40 as a void where no diamond exists on the inside of the grooves 20. The diamond-coated body 1 in which the coating layer 30 has been formed is then smoothed on the surface of the coating layer 30 according to the required performance as a tool. For smoothing in this case, a method is employed in which the laser irradiation area is displaced along the surface of the coating layer 30 (for example, the laser processing method described in Japanese Patent No. 6562536; Pulse Laser Grinding).

[0025] (2) Variant Although embodiments of the present invention have been described above, it goes without saying that the present invention is not limited in any way to the above embodiments and can take various forms as long as they fall within the technical scope of the present invention.

[0026] For example, in the above embodiment, a diamond-coated body 1 is provided as an example in which a coating layer 30 is formed on a tool having a relief surface 11 and a rake surface 13 as the base material 10. However, the diamond-coated body 1 may also be a base material 10 used for purposes other than tools, on which the coating layer 30 is formed.

[0027] Furthermore, in the above embodiment, the groove portion 20 was exemplified as a groove that extends straight in a third direction intersecting the rake face 13. However, the groove portion 20 may also be formed as a V-shaped groove in which the groove width w gradually narrows in the depth direction, as shown in Figures 5(a) and 5(b).

[0028] Furthermore, in the above embodiment, a configuration in which the low-density portion 40 is formed as a void where diamond is absent was illustrated. However, the low-density portion 40 may be formed from a component with a lower Young's modulus than the material of the base material 10.

[0029] Furthermore, in the above embodiment, each groove 20 is shown as extending along the first direction, that is, formed as a single groove extending in the first direction. However, the groove 20 does not necessarily have to be formed as a single groove; multiple grooves or holes may be formed along the first direction, thereby creating a pseudo-groove that extends in the first direction as a whole.

[0030] (3) Effects The diamond coating 1 of the above embodiment includes a low-density portion 40 with a lower diamond density than the coating layer 30, located at the back of each groove 20. Since this low-density portion 40 is more susceptible to contraction from surrounding pressure than the region formed within the groove 20 in the coating layer 30, even if residual stress is generated around the groove 20, it can be relieved by contracting in response to this pressure (see Figure 6).

[0031] This prevents the occurrence of defects such as damage to the area formed within the groove 20 in the coating layer 30 due to residual stress around the groove 20, and suppresses peeling of the coating layer 30 caused by this defect.

[0032] Furthermore, the applicant has found that when the low-density portion 40 occupies 10% to 80% (preferably 20 to 70%) of the area of ​​the groove portion 20 in a cross-sectional view along a direction intersecting the first direction, it is possible to improve the adhesion between the substrate 10 and the coating layer 30 due to the groove portion 20 while simultaneously mitigating residual stress caused by the low-density portion 40. Therefore, in the diamond coating 1 of the above embodiment, it is possible to achieve both improved adhesion between the substrate 10 and the coating layer 30 due to the groove portion 20 and mitigation of residual stress caused by the low-density portion 40. [Industrial applicability]

[0033] The diamond coating of the present invention can be used in components that require wear resistance, such as tools. [Explanation of symbols]

[0034] 1...Diamond coating, 10...Substrate, 11...Flap surface, 13...Scoop surface, 20...Groove, 30...Coating layer, 40...Low density area.

Claims

1. A substrate composed of a material with a greater coefficient of thermal expansion than diamond, having surface regions extending along a first and second intersecting direction, Each of the surface regions of the substrate comprises a plurality of grooves extending along the first direction and spaced apart in the second direction, A coating layer made of diamond material that covers the surface area of ​​the substrate together with each of the grooves, Each of the grooves is formed on the inner side and comprises a low-density portion where the diamond density is lower than that of the coating layer, The low-density portion occupies 10% to 80% of the area of ​​the groove portion in a cross-sectional view along a direction intersecting the first direction. The coating layer is formed with a thickness of 1 to 50 μm. moreover, The groove portion is In a cross-sectional view along a direction intersecting the first direction, when two virtual circles, each having a diameter equal to the thickness t of the coating layer, are positioned so as to straddle the groove and contact each other along the axis extending from the groove, the groove width w corresponds to the distance between the contact points with the surface area of ​​the substrate in each of the virtual circles. The groove width w is defined by the formula [w ≤ t + t × cosθ], which is based on the angle θ formed between the virtual line from the point of contact with the surface region of the substrate to the center in the virtual circle and the second direction. The low-density portion is formed as a void where diamond is not present. Diamond-coated material.

2. The aforementioned base material is made of cemented carbide and is used in tools that have a rake face and a flank face. The groove and the coating layer are formed on the surface region that forms the scooping surface. The diamond coating according to claim 1.

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