Bite tool, and manufacturing method of bite tool

Abstract

To provide a bite tool which is superior in processing accuracy as a bite tool, and with which high adhesivity to a base can be obtained, and to provide a manufacturing method of the bite tool.SOLUTION: A bite tool comprises a base 30, and a cutting edge 20 brazed to the base. The cutting edge comprises an HPHT single crystal diamond base plate 21; and a CVD single crystalline diamond layer 22 deposited on the HPHT single crystal diamond base plate. The cutting edge and the base are adhered to each other such that the CVD single crystalline diamond layer of the cutting edge and the base are mutually opposed.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a turning tool for grinding and cutting a workpiece, and a method for manufacturing the turning tool. [Background technology]

[0002] Diamond is the hardest material and is used in machining tools for various materials such as silicon. In recent years, cutting tools with single-crystal diamond cutting edges have been attracting attention.

[0003] Single crystal diamonds include natural diamonds and synthetic diamonds. Most natural diamonds are type Ia, with nitrogen in the lattice or interstitial spaces. Although type IIa natural diamonds exist, there is a large variation in the impurity content and crystalline structure, resulting in inconsistent quality and performance, and unstable supply. Furthermore, the price of natural diamonds fluctuates depending on the amount mined, making stable supply an issue, and they are expensive and difficult to obtain. On the other hand, synthetic diamonds can be produced with a consistent quality more consistently than natural diamonds, and their supply is stable.

[0004] Therefore, in recent years, synthetic diamonds that are inexpensive and exhibit high durability have been studied. For example, Patent Document 1 proposes a tool using a single-crystal diamond that combines high hardness and high toughness, is easy to process during tool manufacturing, is as resistant to cracking or chipping as or more resistant to cracking than tools using natural products or high-temperature, high-pressure synthetic Ib products, and has a long life and high chipping resistance during cutting. Patent Document 1 also discloses a technology in which CVD single-crystalline diamond is epitaxially grown by chemical vapor deposition (hereinafter referred to as "CVD") on a seed substrate produced by high-pressure and high-temperature (hereinafter referred to as "HPHT"), and the CVD single-crystalline diamond layer separated from the seed substrate is used.

[0005] Patent Document 2 discloses a tool using a single crystal diamond suitable for diamond products, which suppresses the stress that accumulates between the epitaxially grown single crystal and the substrate. To solve this problem, the invention described in Patent Document 2 investigates alleviating the stress caused by depositing single crystal diamond on the side surfaces as well as the main surface of the HPHT substrate by CVD. This document states that forming a carbonaceous layer on the side surfaces of the HPHT substrate can alleviate the stress on the CVD single crystal diamond layer. Patent Document 2 also discloses separating the HPHT single crystal diamond substrate from the CVD single crystal diamond layer deposited thereon, and using the CVD single crystal diamond layer in a tool.

[0006] Meanwhile, Patent Document 3 discloses a technique of using a HPHT single crystal diamond substrate to improve the toughness and / or wear resistance of a tool. Specifically, the patent discloses a tool in which at least a portion of the HPHT diamond tool piece contains a ratio of aggregate nitrogen centers to C-nitrogen centers of more than 30%. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2014 / 003110 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-34114 [Patent Document 3] Special Publication No. 2019-523741 Summary of the Invention [Problem to be solved by the invention]

[0008] It is known that a CVD single-crystalline diamond layer has a relatively rough surface because stress with the substrate cannot be avoided during epitaxial growth. For this reason, the inventions described in Patent Documents 1 and 2 investigate the relaxation of stress in a CVD single-crystalline diamond layer deposited on an HPHT single-crystalline diamond substrate.

[0009] However, even if the CVD single-crystalline diamond layers described in Patent Documents 1 and 2 are used in tools, it cannot be said that stress is sufficiently alleviated. Even if the methods discussed in these documents are used, there is a limit to the stress alleviation, and stress remains in the CVD single-crystalline diamond. In particular, in the case of cutting tools, further study is required because high machining accuracy is required for workpieces in recent years.

[0010] Furthermore, CVD single-crystalline diamond layers are known to be more difficult to process than HPHT single-crystalline diamond substrates, and as mentioned above, CVD single-crystalline diamond layers tend to have relatively poor processing accuracy due to the influence of stress during epitaxial growth.

[0011] Furthermore, since the cutting edge of the cutting tool needs to be polished after use to maintain processing accuracy, a thick plate is preferable. However, obtaining a thick single-crystal diamond using HPHT is time-consuming and expensive.

[0012] On the other hand, paragraph 0019 of Patent Document 3 states that when the ratio of aggregated nitrogen center to C-nitrogen center is more than 30%, aggregated nitrogen center reduces the lattice distortion of diamond compared with the diamond crystal lattice that consists only of C-center.This is because both the time and temperature of annealing affect the ratio of aggregated nitrogen center to C-center.

[0013] Here, paragraph 0014 of Patent Document 3 discloses that a diamond tool is formed by brazing a diamond tool piece to a carrier. However, since the surface of an HPHT single crystal diamond substrate is smooth, it is difficult to obtain a strong adhesive force even when brazed.

[0014] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a cutting tool that is excellent in machining accuracy as a cutting tool and that can obtain high adhesive strength with a base, and a method for manufacturing the cutting tool. [Means for solving the problem]

[0015] Conventionally, turning tools using either a CVD single-crystalline diamond layer or an HPHT single-crystalline diamond substrate have been used, as disclosed in Patent Documents 1 to 3. For this reason, it has been difficult to combine the advantages of both.

[0016] From the viewpoint of improving grinding accuracy and good processability, the inventors first used HPHT single crystal diamond substrates and investigated whether high adhesive strength could be achieved by conventional brazing. Although silver brazing or Cu brazing is used for brazing, which is the process of bonding the cutting edge to the base, it may be worthwhile to investigate brazing materials that can further improve adhesive strength.

[0017] However, because single-crystal diamond is not a metal, it is not easy to improve adhesive strength by brazing, especially in the case of HPHT single-crystal diamond substrates. This is presumably because single-crystal diamond is not only chemically stable but also thermally stable, making it difficult for the constituent elements to interdiffuse near the bonding interface between the brazing material and the single-crystal diamond.

[0018] Therefore, the inventors came up with the idea of ​​improving the adhesive strength physically, rather than metallurgically, and after further investigation, came up with the idea of ​​using the CVD single-crystalline diamond layer as a cutting edge, without separating it from the HPHT single-crystalline diamond substrate as in the conventional method.

[0019] In addition, problems such as crystal quality and difficulty in processing the cutting edge itself have been considered. This is thought to be due to the fact that stress is applied when a CVD single-crystalline diamond layer is deposited by epitaxial growth on an HPHT single-crystalline diamond substrate, resulting in a relatively large amount of surface irregularities. Therefore, the inventors came up with the idea of ​​bonding a CVD single-crystalline diamond layer deposited on an HPHT single-crystalline diamond substrate to a base.

[0020] It has been known that single crystal diamonds formed by depositing a CVD single crystal diamond layer on an HPHT single crystal diamond substrate suffer from various degradation characteristics due to internal stress, and for this reason, the use of single crystal diamonds formed by depositing a CVD single crystal diamond layer on an HPHT single crystal diamond substrate for cutting tools has been avoided.

[0021] However, the present inventors decided to use a cutting edge made by depositing a CVD single-crystalline diamond layer on an HPHT single-crystalline diamond substrate, which has traditionally been avoided. Furthermore, the present inventors brazed the cutting edge to the base so that the CVD single-crystalline diamond layer faced the base. As a result, a cutting tool using a cutting edge made of single-crystalline diamond with high grinding accuracy and adhesive strength to the base was obtained, and the present invention was completed. The present invention, which was made based on these findings, is as follows.

[0022] (1) A tool having a base and a cutting edge brazed to the base, the cutting edge comprises a HPHT single crystal diamond substrate and a CVD single crystal diamond layer deposited on the HPHT single crystal diamond substrate; The cutting edge and base are bonded together so that the CVD single-crystalline diamond layer on the cutting edge faces the base. A turning tool characterized by:

[0023] (2) The turning tool according to (1) above, wherein the thickness of the HPHT single crystal diamond substrate is 0.3 to 3.0 mm.

[0024] (3) The turning tool according to (1) or (2) above, wherein the thickness of the CVD single-crystalline diamond layer is 0.1 to 2.0 mm.

[0025] (4-5) The turning tool according to any one of (1) to (3) above, wherein the CVD single-crystalline diamond layer is transparent or yellow in color.

[0026] (6-9) The cutting tool according to any one of (1) to (5) above, wherein the surface-nearby region of the CVD single-crystalline diamond layer exhibits a color different from that of the region other than the surface-nearby region of the CVD single-crystalline diamond layer.

[0027] (10) A manufacturing method of a cutting tool having a base and a cutting edge brazed to the base, a CVD single-crystalline diamond layer deposition step of depositing a CVD single-crystalline diamond layer on a pre-prepared HPHT single-crystalline diamond substrate by a CVD method in an atmosphere gas containing an additive gas composed of at least one of oxygen, nitrogen, and / or nitrogen oxides; A method for manufacturing a cutting tool, comprising: a cutting edge bonding step of bonding a cutting edge formed by depositing a CVD single-crystalline diamond layer on an HPHT single-crystalline diamond substrate in a CVD single-crystalline diamond layer deposition step to a base by brazing so that the CVD single-crystalline diamond layer faces the base.

[0028] (11) A method for manufacturing a cutting tool as set forth in (10) above, wherein the amount of additive gas introduced is increased to 2 to 200 times the amount of additive gas introduced in a time period from the last 20 to 0.5% of the process time of the CVD single-crystalline diamond layer deposition step onward.

[0029] (12) The method for manufacturing a cutting tool according to (10) above, wherein the additive gas is introduced only during the last 20 to 0.5% or later of the process time of the CVD single-crystalline diamond layer deposition step.

[0030] (13) A method for manufacturing a turning tool according to any one of (10) to (12) above, comprising a grinding and flattening step of grinding and flattening the deposition surface of the CVD single-crystalline diamond layer deposited in the CVD single-crystalline diamond layer deposition step so that the deposition surface is at least partially parallel to the surface of the HPHT single-crystalline diamond substrate.

[0031] (14) A cutting tool according to any one of (1) to (9) above, wherein a plurality of convex portions are formed on the surface of the CVD single-crystalline diamond layer, and the difference in height from the lowest to the highest of the convex portions is 0.05 mm or more.

[0032] (15) A cutting tool according to any one of (1) to (9) above, wherein the area of ​​the surface of the CVD single-crystalline diamond layer that is parallel to the HPHT single-crystalline diamond substrate is 30 to 95% of the surface area of ​​the CVD single-crystalline diamond layer.

[0033] (16) The turning tool according to any one of (1) to (9) above, wherein the interval between the protruding portions of abnormal growth is at least half the width of the CVD single-crystalline diamond layer. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 is a perspective view of a cutting tool according to this embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the turning tool according to this embodiment. [Figure 3] FIG. 3 is a perspective view of a cutting edge that constitutes the turning tool according to this embodiment. [Figure 4] Figure 4 is a perspective view showing the manufacturing process of the cutting tool according to this embodiment, in which Figure 4(a) is a perspective view of a pre-prepared HPHT single crystal diamond substrate, Figure 4(b) is a perspective view of the HPHT single crystal diamond substrate on which a CVD single crystalline diamond layer has been deposited by the CVD method, and Figure 4(c) is a perspective view of the cutting edge of the HPHT single crystal diamond substrate on which the CVD single crystalline diamond layer has been deposited, with the CVD single crystalline diamond layer and base bonded together. [Figure 5] FIG. 5 is a profile showing the relationship between gas species and deposition time (%), illustrating an example of deposition conditions for CVD single-crystalline diamond in the manufacturing process for the cutting tool according to this embodiment. [Figure 6]Figure 6 is a cross-sectional view of a cutting edge manufactured by the method for manufacturing a cutting tool according to this embodiment, showing the state before and after grinding and flattening the surface of the cutting edge so that it is parallel to the HPHT single crystal diamond substrate of the cutting edge. Figure 6(a) is a cross-sectional view of the cutting edge before grinding and flattening, and Figure 6(b) is a cross-sectional view of the cutting edge after grinding and flattening. [Figure 7] Figure 7 is an optical microscope photograph of the cutting edge of the cutting tool according to this embodiment, in which Figure 7(a) is the HPHT single crystal diamond substrate before the CVD single crystal diamond layer is deposited in Example 2, and Figure 7(b) is the CVD single crystal diamond layer deposited on the HPHT single crystal diamond substrate in Example 2. [Figure 8] Figure 8 shows photographs of the cutting edge of Example 2, in which the CVD single-crystalline diamond layer was deposited under the deposition conditions where the amount of nitrogen introduced was increased from 0.05 volume parts to 0.20 volume parts when the amount of hydrogen introduced was 100 volume parts for the final 5 hours of the total deposition time, Figure 8(a) is an optical microscope photograph of the cutting edge, and Figure 8(b) is an SEM photograph of the cutting edge after grinding and flattening. [Figure 9] Figure 9 shows photographs of the cutting edge of Example 3, in which the CVD single-crystalline diamond layer was deposited under the deposition conditions where the amount of nitrogen introduced was increased from 0.10 volume parts to 0.50 volume parts when the amount of hydrogen introduced was 100 volume parts for the last 3 hours of the total deposition time, Figure 9(a) is an optical microscope photograph of the cutting edge, and Figure 9(b) is an SEM photograph of the cutting edge after grinding and flattening. DETAILED DESCRIPTION OF THE INVENTION

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments. Furthermore, the present invention may be implemented in a combination of the embodiments.

[0036] 1. Tool bits (1) Overview of tool bits FIG. 1 is a perspective view of a cutting tool 1 according to this embodiment. FIG. 2 is an exploded perspective view of the cutting tool 1 according to this embodiment. The cutting tool 1 shown in FIGS. 1 and 2 is composed of a cutting edge 20 and a base 30 to which the cutting edge 20 is fixed with brazing material. It may be used as the cutting tool 1 as is, but depending on the grinding device, the cutting edge portion 10 composed of the cutting edge 20 and the base 30 to which the cutting edge 20 is fixed may be detachably attached to a shank 34 with a fastening bolt 38.

[0037] The shank 34 is formed of stainless steel in the shape of a square pillar, as shown in Fig. 1, and has a tapered mounting portion 341 at its tip (lower end). It may be cylindrical, and may have any shape that suits the specifications of the grinding machine (not shown). A female screw hole 343 is formed in a mounting surface 342 of the mounting portion 341, as shown in Fig. 2.

[0038] The base 30 is formed from a hard material such as tungsten carbide, and includes a mounting portion 301 having a mounting surface 301a that is detachably mounted on the shank 34, and a tip mounting portion 302 to which the cutting edge 20 is brazed. Note that, although the illustrated embodiment shows an example in which the mounting portion 301 and the tip mounting portion 302 that constitute the base 30 are integrally molded, the mounting portion 301 and the tip mounting portion 302 may be formed separately and then brazed together.

[0039] The base 30 formed in this manner has a tip mounting portion 302 to which the cutting edge 20 is brazed, which protrudes from the front surface 301b of the mounting portion 301, and the cutting edge 20 is brazed to the tip mounting surface 302a, which is the front surface of this tip mounting portion 302, using a brazing material such as silver-tin.

[0040] The distance between the front surface 301b of the mounting portion 301 constituting the base 30 and the chip mounting surface 302a is set to 5 mm in the illustrated embodiment, for example, but is not particularly limited as long as it is about 3 to 10 mm.

[0041] The thickness of the cutting edge 20 is set to 2 mm in the illustrated embodiment, but may be approximately 0.5 to 5 mm. A bolt insertion hole 303 is provided in the mounting portion 301 of the base 30. The fastening bolt 38 is inserted into the bolt insertion hole 303 and threaded into the bolt insertion hole 303 formed in the shank 34, thereby attaching the base 30 to the shank 34. The cutting tool 1 configured as above, or the shank 34 to which the cutting tool 1 is attached, is attached to a grinding device (not shown).

[0042] (2) Cutting edge 3 is a perspective view of a cutting edge portion 10 constituting the cutting tool according to this embodiment. The cutting edge 20 according to the present invention is a single crystal diamond, and is composed of an HPHT single crystal diamond substrate 21 and a CVD single crystal diamond layer 22 deposited on the HPHT single crystal diamond substrate. The cutting edge 20 and base 30 are brazed together with a brazing material 23 so that the CVD single crystal diamond layer 22 constituting the cutting edge portion 10 faces the base 30.

[0043] The HPHT single crystal diamond substrate 21 is either type Ib or type IIa, with type Ib being preferred. Furthermore, from the viewpoint of reusing the cutting edge of the cutting tool by grinding and polishing it after use, the plate thickness is preferably 0.3 mm or more, more preferably 0.5 mm or more, and may be 1.5 mm or more. There is no particular upper limit, but within the manufacturable range, it is sufficient if it is 3.0 mm or less, and may be 2.0 mm or less.

[0044] Since the CVD single-crystalline diamond layer 22 is deposited using the CVD method, a thickness greater than necessary is undesirable from the standpoint of cost. For this reason, in this embodiment, the upper limit is preferably 2.0 mm or less. The lower limit should be a thickness sufficient to form the irregularities described below, so a thickness of 0.05 mm or more is sufficient, and 0.10 mm or more is preferable.

[0045] If the HPHT single crystal diamond substrate 21 is thick, the CVD single crystalline diamond layer 22 may be thin. If the HPHT single crystal diamond substrate 21 is thin, the CVD single crystalline diamond layer 22 may be thick. Generally, it takes a long time to thicken the HPHT single crystal diamond substrate 21, so the CVD single crystalline diamond may be thick. If the CVD single crystalline diamond layer 22 is thick, at least the CVD single crystalline diamond layer 22 or its surface may be of low quality, and the CVD single crystalline diamond may have large irregularities on its surface.

[0046] Considering the life of the cutting edge, it is better to have a thick HPHT single crystal diamond substrate 21. In this case, the CVD single crystal diamond layer 22 may be thin within the above range, as long as it has enough irregularities to prevent peeling from the base 30.

[0047] The surface of the CVD single crystalline diamond layer 22 is rougher than that of the HPHT single crystal diamond substrate 21. This allows for stronger adhesion compared to when the HPHT single crystal diamond substrate 21 is directly brazed to the base 30. The reason why strong adhesion is possible is presumed to be as follows: Because the brazing filler metal 23 is molten during bonding, the molten brazing filler metal 23 penetrates into recesses in the CVD single crystalline diamond layer 22. Therefore, the surface with irregularities has a larger specific surface area than a smooth surface, and so the contact area between the brazing filler metal 23 and the CVD single crystalline diamond layer 22 after solidification increases, allowing for stronger adhesion. The irregularities will be described later.

[0048] In order for the CVD single crystalline diamond layer 22 to be more firmly bonded to the base 30, it is better for the CVD single crystalline diamond layer 22 to have poorer crystal quality. Conventionally, the CVD single crystalline diamond layer 22 epitaxially deposited on the HPHT single crystal diamond substrate 21 has been peeled off from the HPHT single crystal diamond substrate 21 and used alone. For this reason, the HPHT single crystal diamond substrate on which the CVD single crystalline diamond layer 22 has been deposited has not conventionally been used as is for tools or the like.

[0049] However, in the cutting tool according to this embodiment, the CVD single crystalline diamond layer 22 is configured based on a technical concept that is the exact opposite of conventional ones in order to strengthen the brazing to the base 30. In other words, it is preferable to use a CVD single crystalline diamond layer 22 with a rough surface and a crystal quality equal to or lower than that of the HPHT single crystalline diamond substrate 21. The color of the CVD single crystalline diamond layer 22 may be transparent or yellow, with yellow being preferred.

[0050] The inclusion of nitrogen in the cutting edge 20 strengthens the bond at the homoepitaxial growth interface between the HPHT single crystal diamond substrate 21 and the CVD single crystalline diamond layer 22, and reduces crystal stress caused by deposition. Furthermore, the nitrogen incorporated into the diamond crystal reduces the quality of the diamond crystal, and when deposition of the CVD single crystalline diamond layer 22 is completed, the entire CVD single crystalline diamond layer 22 or the surface of the CVD single crystalline diamond layer 22 becomes rough. As a result, the bond strength with the brazing material 23 increases, and peeling from the base 30 can be suppressed.

[0051] In the present invention, the near-surface region of the CVD single-crystalline diamond layer 22 may have a different color from the remaining regions of the CVD single-crystalline diamond layer 22. In other words, even if the CVD single-crystalline diamond layer 22 is deposited under conventional deposition conditions aiming for high quality, if the crystalline quality of the near-surface region is degraded, the near-surface region and the remaining regions will have different colors. If the color of the near-surface region of the CVD single-crystalline diamond layer 22 is darker than the color of the remaining regions, the crystalline quality of the bonding surface of the CVD single-crystalline diamond layer 22 will be more degraded, and surface irregularities and pores will be more pronounced, resulting in stronger brazing adhesion. Furthermore, the crystalline quality of the CVD single-crystalline diamond layer 22 will be degraded due to the inclusion of nitrogen compared to a crystal without nitrogen inclusion, making it easier to machine the cutting edge itself.

[0052] In the present invention, as mentioned above, although the colours of these regions are different in a preferred embodiment, the amount of nitrogen is increased during deposition to deteriorate the crystal quality of the near-surface region of CVD single crystalline diamond layer 22. For this reason, the colour of the near-surface region of CVD single crystalline diamond layer 22 may be a deeper yellow than the colour of the other regions, or may have changed to a colour other than yellow, such as purple or brown. Naturally, although at least the near-surface region of CVD single crystalline diamond layer 22 has a colour different from the other regions, it is not colourless.

[0053] The darker the yellow, the higher the nitrogen content and the poorer the crystal quality. Yellow can be distinguished, for example, based on the GIA Color Scale D to Z. Colors darker than Z can be determined using a dark color scale distinguished as fancy colors. Fancy colors include dark yellow, green, red, green, orange, pink, blue, purple, navy blue, and black. Colors are classified in order of lightness as faint, very light, light, fancy light, fancy, fancy dark, and fancy deep. In the present invention, the darker the color, the poorer the crystal quality, which strengthens the brazing and prevents separation between the base 30 and the cutting edge 20. Color classification can also be performed visually.

[0054] Alternatively, the crystal quality of the CVD single crystalline diamond layer 22 may be defined by the half-width of the Raman spectrum. When the Raman spectrum of the CVD single crystalline diamond layer 22 is used to define the crystal quality, the FWHM, which is the half-width of the peak of the CVD single crystalline diamond layer 22, is set to 1.0 to 5.0 cm. -1 Furthermore, the peak shift amount may be determined by shifting the peak of a type Ia natural diamond containing an extremely small amount of nitrogen or an artificial type IIa diamond to 1333.0 cm. -1 The peak shift amount of the CVD single crystalline diamond layer 22 is −1.0 to +1.0 cm -1The surface of the CVD single-crystalline diamond layer 22 that satisfies at least one or all of these conditions will be rough, improving the adhesive strength of the brazing material. In some cases, if pores are formed, even stronger adhesion will be possible.

[0055] In the present invention, the "near-surface region of the CVD single-crystalline diamond layer" refers to a depth of up to 0.1 mm from the surface of the CVD single-crystalline diamond layer 22. For example, if the film thickness of the CVD single-crystalline diamond layer 22 is 0.1 mm, the overall crystal quality of the CVD single-crystalline diamond layer 22 will be poor.

[0056] Furthermore, the CVD single crystalline diamond layer 22 constituting the cutting edge 20 may have recesses 22-1 or protrusions 22-2 formed by roughening the surface, as shown in Figure 6(b), for example. Recesses 22-1 may be formed when holes are formed in the flat surface of the CVD single crystalline diamond layer 22. Protrusions 22-2 correspond to the tops of abnormally grown areas. The formation of protrusions 22-2 also forms recesses 22-1 at the same time.

[0057] In this embodiment, the greater the height difference 50 from the bottom end of the recess 22-1 to the top end of the protrusion 22-2, the greater the specific surface area of ​​the CVD single crystalline diamond layer 22, and the more the brazing material flows into the recess 22-1 when melted, enabling stronger adhesion. When grinding is performed for smoothing after depositing the CVD single crystalline diamond layer 22, the height difference is the difference between the bottom end of the recess 22-1 and the highest point of the protrusion 22-2 after grinding and flattening. The height difference 50 is preferably more than 0.05 mm but not more than 0.5 mm, and most preferably more than 0.1 mm. The height difference can be obtained by observing the cross section of the cutting edge 20 with an optical microscope.

[0058] Furthermore, if the spacing 60 between the protrusions 22-2 on the ground surface as shown in Figure 6(b) is at least 1 / 2 of the width 70 of the CVD single-crystalline diamond layer 22, the cutting edge 20 can be stably placed on the base 30. More preferably, the spacing 60 is at least 3 / 5 of the width 70, and most preferably at least 7 / 10. As shown in Figure 6(b), grinding flattens the tips of the protrusions 22-2. In this case, as shown in Figure 6(b), the spacing 60 may be measured on the parallel surface 22-4 using the portion 22-3 near the outside of the cutting edge 20 as a reference.

[0059] In addition, as shown in Figure 6(b), it is preferable that the surface of the CVD single crystalline diamond layer 22 has a surface 22-4 parallel to the HPHT single crystal diamond substrate 21. The presence of such parallel surface 22-4 allows the layer to be stably mounted on the base 30. The area of ​​surface 22-4 parallel to the HPHT single crystal diamond substrate on the surface of the CVD single crystalline diamond layer is preferably 30 to 95% of the surface area of ​​the CVD single crystalline diamond layer.

[0060] When the area ratio is 30 to 49%, and the parallel faces 22-4 are biased toward the end of the CVD single-crystalline diamond layer, it is preferable that the cutting edge 20 be placed more stably. In this case, it is preferable that the spacing 60 between the protrusions 22-2 is within the above-mentioned range.

[0061] As mentioned above, conventionally, after a CVD single-crystalline diamond layer 22 is deposited on an HPHT single-crystal diamond substrate 21, the CVD single-crystalline diamond layer 22 is separated from the HPHT single-crystal diamond substrate 21 and used as a cutting edge. This is because there is a concern that the CVD single-crystalline diamond layer 22 deposited on the HPHT single-crystal diamond substrate 21 is prone to breakage during machining because a state in which the CVD single-crystalline diamond layer 22 remains stressed. Furthermore, because the quality of the CVD single-crystalline diamond layer 22 differs from the crystalline quality of the HPHT single-crystal diamond substrate 21, it is difficult to achieve machining precision equivalent to that of the HPHT single-crystal diamond substrate 21. Therefore, conventionally, the HPHT single-crystal diamond substrate 21 and the CVD single-crystalline diamond layer 22 have had to be separated.

[0062] However, CVD requires a long time to deposit a thick single-crystal diamond, and the separation process also requires time, so the cost is undeniably high. On the other hand, if only the HPHT single-crystal diamond substrate 21 is used for the cutting edge 20, the high quality of the HPHT single-crystal diamond substrate 21 will actually result in a poor adhesive strength with the brazing material 23.

[0063] In consideration of these circumstances, the cutting tool 1 of the present invention solves the above-mentioned problems by using a single crystal diamond as the cutting edge 20, which is a single crystal diamond having a CVD single crystal diamond layer 22 deposited on an HPHT single crystal diamond substrate 21, something that has been avoided in the past.

[0064] 2. Manufacturing method of cutting tools The manufacturing method of the cutting tool according to the present invention will be described with reference to Fig. 4. Fig. 4 is a perspective view showing the manufacturing process of the cutting tool according to this embodiment.

[0065] The manufacturing method of the cutting tool according to the present invention comprises a CVD single crystalline diamond layer deposition step of depositing a CVD single crystalline diamond layer 22 on an HPHT single crystalline diamond substrate 21 by a CVD method, and a cutting edge bonding step of brazing the cutting edge 20, on which the CVD single crystalline diamond layer 22 has been deposited on the HPHT single crystalline diamond substrate 21 by the CVD single crystalline diamond layer deposition step, to a base 30 using a brazing filler 23 so that the CVD single crystalline diamond layer 22 faces the base 30. The steps will be explained below in order with reference to FIG.

[0066] (1) CVD single-crystalline diamond layer deposition process As shown in FIG. 4(a), a HPHT single-crystal diamond substrate 21 manufactured by a conventional method is prepared. Then, as shown in FIG. 4(b), a CVD single-crystalline diamond layer 22 is deposited on the HPHT single-crystal diamond substrate 21 to form a cutting edge 20. In the manufacturing method according to the present invention, the CVD single-crystalline diamond layer 22 is deposited by epitaxial growth using, for example, a microwave plasma CVD apparatus. Any conventional CVD method, such as microwave CVD or DC plasma CVD, can be used. The deposition conditions may be, for example, a deposition temperature of 700 to 1300°C, an atmosphere of approximately 50 to 300 Torr, and an additive gas composed of at least one of oxygen, nitrogen, and / or nitrogen oxides in addition to the main gases of hydrogen and methane.

[0067] Furthermore, from the viewpoint of improving the adhesive strength with the brazing material 23, the CVD single crystalline diamond layer 22 constituting the present invention preferably has many irregularities formed on the surface thereof at the end of deposition.

[0068] Furthermore, it is preferable to deposit the CVD single crystal diamond layer 22 with a larger amount of additive gas introduced than in the past, in order to avoid deteriorating the crystal quality of the CVD single crystal diamond layer 22. For example, in the past, a CVD single crystal diamond layer was deposited with an additive gas introduction amount of less than 0.1 parts by volume, assuming that hydrogen, which constitutes the main gas, is 100 parts by volume, but if the additive gas introduction amount is increased to 0.1 to 2.0 parts by volume, as in this embodiment, the adhesive strength of the brazing material is improved and interfacial fracture at the HPHT single crystal diamond substrate 21 is also suppressed.

[0069] The atmospheric gas used in the CVD single-crystalline diamond layer deposition process may contain, in addition to the main gases hydrogen and methane, additive gases such as nitrogen, oxygen, and nitrogen oxides. When the atmospheric gas is composed of a mixture of these gases, the amount of each gas introduced is determined by assuming the amount of hydrogen introduced is 100 parts by volume. The amounts of methane and additive gas that constitute the main gas introduced may be methane introduced: additive gas introduced = 10.0-2.0 parts by volume: 0.0-2.0 parts by volume, preferably 10.0-2.0 parts by volume: 0.01-2.0 parts by volume. The volume ratio of the amount of additive gas introduced to the amount of methane introduced may be 0.00-40.00%. When the amount of additive gas introduced is increased during the CVD single-crystalline diamond layer deposition process, it may be 0.00-2.00% initially, and may be increased to 0.50-40.00% partway through. This volume ratio is the percentage (%) obtained by multiplying the amount of additive gas introduced divided by the amount of methane introduced by 100.

[0070] If the crystal quality of the CVD single-crystalline diamond layer 22 is significantly degraded, it is preferable to increase the proportion of the added gas. 3 The methane intake is 5m 3 The amount of added gas introduced was 0.05 m 3 In this case, the amount of methane introduced: the amount of added gas introduced = 5 parts by volume: 0.05 parts by volume, resulting in a volume ratio of 5:0.05. The added gas is preferably at least one of oxygen, nitrogen, and / or an oxide of nitrogen, and more preferably nitrogen, NO2, or NO.

[0071] In addition, in order to further deteriorate the crystalline quality of the surface of the CVD single-crystalline diamond layer 22, it is preferable to increase the additive gas concentration in a time range of 20.0 to 0.5% of the deposition time of the CVD single-crystalline diamond layer 22, this time range being the time range up to the end of the deposition time, and to increase the additive gas concentration in this time range to 2 to 200 times the additive gas concentration in other time ranges. For example, if the deposition time is 50 hours, the additive gas concentration in the atmospheric gas is 10 hours, which is 20% of the deposition time, and the additive gas concentration increases to 2 to 200 times the previous level 10 hours before the end of deposition. For example, the temperature profile shown in Figure 5 may be used.

[0072] In this embodiment, the atmospheric gas conditions at the start of the CVD single-crystalline diamond layer deposition process may be referred to as the “first stage,” and the atmospheric gas conditions in the time region after the additive gas is newly introduced or the amount of additive gas introduced is increased may be referred to as the “second stage.” In Figure 5, the first stage covers 0 to 80% of the volume time (%), and the second stage covers 80 to 100%.

[0073] In the manufacturing method according to the present invention, rather than increasing the amount of additive gas introduced from the second stage onwards, it is also possible to introduce a larger amount of additive gas than conventionally introduced from the first stage and maintain that amount throughout. In this case, the crystal quality of the entire CVD single crystalline diamond layer 22 will be inferior. For this reason, if the volume ratio of the amount of additive gas introduced to the amount of methane introduced is 1.1% or more from the beginning of the CVD single crystalline diamond layer deposition process, it is not necessary to increase the concentration of the additive gas midway through. Naturally, even if the volume ratio is within this range, the concentration of the additive gas may be increased midway through.

[0074] Furthermore, if the CVD single-crystalline diamond layer deposition step is started in an atmosphere to which no additive gas is added, the additive gas may be introduced only during the aforementioned time period.

[0075] In this embodiment, the additive gas may be introduced or the amount of additive gas introduced may be increased at any time. By doing so, even if a high-quality CVD single-crystalline diamond layer 22 is deposited partway through, the crystal quality of the surface of the CVD single-crystalline diamond layer 22 will be poor, and large irregularities will occur in the surface of the CVD single-crystalline diamond layer 22, resulting in differences in height. This makes it possible to suppress peeling from the base 30.

[0076] The cutting tool according to this embodiment is manufactured so that the quality of the CVD single crystalline diamond layer 22 deteriorates. As a result, abnormal growth occurs in places on the deposition surface of the CVD single crystalline diamond layer 22. In this embodiment, even if there are areas of abnormal growth, forming unevenness on the growth surface can suppress peeling from the base 30. However, if the areas of abnormal growth are left as they are, stable brazing to the base 30 may not be possible.

[0077] Therefore, the manufacturing method of the cutting tool according to this embodiment may include a grinding and flattening step in which the deposition surface of the CVD single crystalline diamond layer 22 is ground and flattened before the cutting edge bonding step described below. The grinding and flattening step is a step in which the abnormally grown areas 22-2 are ground and flattened so that the deposition surface of the CVD single crystalline diamond layer 22 is partially parallel to the surface of the HPHT single crystal diamond substrate 21. The grinding and flattening step makes it possible to join the cutting edge 20 and the base 30 on parallel surfaces 22-4, thereby enabling extremely strong brazing.

[0078] FIG. 6 is a cross-sectional view of a cutting edge manufactured by the method for manufacturing a cutting tool according to this embodiment, showing the cutting edge surface before and after grinding and flattening so that the cutting edge is parallel to the HPHT single crystal diamond substrate. FIG. 6(a) is a cross-sectional view of the cutting edge before grinding and flattening, and FIG. 6(b) is a cross-sectional view of the cutting edge after grinding and flattening. As shown in FIG. 6(a), the deposition surface of the CVD single crystalline diamond layer 22 may have abnormally grown areas 22-2. For this reason, in the method for manufacturing a cutting tool according to this embodiment, the grinding and flattening step may grind the abnormally grown protrusions 22-2 along a line 40 parallel to the surface of the HPHT single crystal diamond substrate 21, as shown in FIG. 6. The grinding and flattening step at least partially forms a surface parallel to the surface of the HPHT single crystal diamond substrate 21.

[0079] The area of ​​these parallel surfaces is adjusted as appropriate depending on the number, locations and growth rate of the protrusions 22-2 formed in the CVD single crystal diamond layer. In the grinding flattening step, it is sufficient to perform the minimum amount of grinding necessary to obtain a surface parallel to the surface of the HPHT single crystal diamond substrate 21.

[0080] Here, in this embodiment, "minimum grinding to obtain a surface parallel to the base" means minimum grinding to obtain a surface parallel to the base 30 to the extent that the cutting edge 20 does not tilt when the cutting edge 20 is placed on the base 30. In other words, if the convex portion 22-2 is biased toward the end of the CVD single-crystalline diamond layer, for example, it is necessary to grind away all of the abnormally grown portions to prevent the cutting edge 20 from tilting when placed on the base 30.

[0081] However, the protrusions 22-2 are often present on the entire surface of the CVD single-crystalline diamond layer, and therefore, as shown in Figure 6(b), by grinding the vicinity of the apex of the protrusions 22-2, the cutting edge 20 will not tilt when placed on the base 30, and the cutting edge 20 can be placed stably.

[0082] A more preferable example of "minimum grinding to obtain a surface parallel to the base" is grinding such that, on the ground surface as shown in FIG. 6(b), the spacing 60 between the protrusions 22-2 is at least half the width 70 of the CVD single-crystalline diamond layer 22, as described above. Such grinding allows the cutting edge 20 to be stably placed on the base 30. More preferably, the spacing 60 is at least 3 / 5 of the width 70, and most preferably at least 7 / 10. As shown in FIG. 6(b), grinding flattens the tips of the protrusions 22-2. In this case, the spacing 60 may be measured using the portion 22-3 near the outside of the cutting edge 20 as a reference point on the flat portion, as shown in FIG. 6(b).

[0083] As one indicator, grinding of the surface of the CVD single crystalline diamond layer 22 may be carried out so as to obtain such a gap 60. Even after the surface of the CVD single crystalline diamond layer 22 has been ground, it is preferable that the height difference 50 on the surface of the CVD single crystalline diamond layer 22 is within the aforementioned range.

[0084] In the CVD single-crystalline diamond layer 22, the convex portions 22-2, which are abnormally grown portions, are ground away in the grinding flattening step, thereby forming surfaces 22-4 parallel to the surfaces of the HPHT single-crystalline diamond substrate 21, as shown in Figure 6(b). The area of ​​the parallel surfaces 22-4 is preferably 30 to 95% of the area of ​​the HPHT single-crystalline diamond substrate.

[0085] Furthermore, when the CVD single-crystalline diamond layer deposition step is carried out as described above, the cutting edge may become covered with polycrystalline CVD diamond and / or diamond-like carbon (hereinafter referred to as "DLC" as appropriate). A step of removing this DLC by grinding may be carried out before the cutting edge bonding step described below.

[0086] The grinding in the grinding flattening step and the DLC removal step may be performed using a normal grinding machine, and the grinding conditions are not particularly limited.

[0087] (2) Blade tip bonding process Finally, as shown in Figure 4(c), the manufacturing method according to the present invention includes a cutting edge bonding step in which cutting edge 20, formed by depositing CVD single crystalline diamond layer 22 on HPHT single crystalline diamond substrate 21 in the CVD single crystalline diamond layer deposition step, is bonded to base 30 by brazing. In the cutting edge bonding step, cutting edge 20 and base 30 are bonded by brazing so that CVD single crystalline diamond layer 22 of cutting edge 20 and base 30 face each other.

[0088] As the brazing material 23 used for brazing, general brazing materials such as silver brazing, copper brazing, etc. Also, as long as the temperature of the cutting tool does not become high when the cutting tool is used or during the grinding process of the cutting edge 20 described below, a high-temperature solder having a melting point higher than the temperature during use or the grinding process may be used.

[0089] Furthermore, brazing may be performed while applying ultrasonic waves to improve the adhesive strength of the cutting edge 20. Applying ultrasonic waves improves the wettability between the brazing material 23 and the cutting edge 20, thereby further improving the adhesive strength.

[0090] The details of the cutting edge bonding process are as follows. First, the brazing filler metal 23 is placed on the base 30 at the location where the cutting edge 20 will be bonded. Alternatively, the brazing filler metal 23 is bonded in advance to a predetermined position, and then the cutting edge 20, which is an HPHT single crystal diamond substrate 21 on which a CVD single crystalline diamond layer 22 has been grown, is placed on the base 30 at the position where the brazing filler metal 23 is placed, or at the position where the brazing filler metal 23 will be bonded. The cutting edge 20 is placed on the base 30 so that the CVD single crystalline diamond layer 22 of the cutting edge 20 faces the base 30 (mounting process). Thereafter, the brazing filler metal 23 is melted at a temperature about 20 to 30°C higher than the melting point of the brazing filler metal 23, and then cooled to bond the cutting edge 20 to the base 30. [Example]

[0091] This embodiment will be described with reference to the following examples. The present invention is not limited to the following examples. Examples 1 to 3 will be described in detail below, but Examples 4 to 16 were performed under the same conditions as Examples 1 to 3 except for the CVD conditions, so their description will be omitted.

[0092] Example 1 First, a 3mm square, 1.0mm thick Ib-type HPHT single-crystal diamond substrate (Element Chic, model number: MXP L3010) was prepared. Its color was fancy yellow. CVD single-crystalline diamond was deposited on this substrate using a microwave plasma CVD apparatus. Hydrogen and methane were used as the main gases, and nitrogen was used as the additive gas. The hydrogen introduction rate was 100 parts by volume, and the methane introduction rate: nitrogen introduction rate = 5.0 parts by volume: 0.10 parts by volume. The CVD single-crystalline diamond layer was deposited for 45 hours at a temperature of 1000°C and a pressure of 100 torr. A 0.5mm thick CVD single-crystalline diamond layer was deposited. The "volume ratio (%) of methane to additive gas," calculated by dividing the amount of additive gas introduction by the amount of methane introduction and multiplying the result by 100, was 2.00%.

[0093] After deposition, the cutting edge was covered with DLC, which had large irregularities, and the DLC was removed by grinding in the same manner as in the conventional method. In other words, in Example 1, after forming the CVD single-crystalline diamond layer, no abnormal growth was observed, as shown in Figure 6, so a surface parallel to the surface of the HPHT single-crystal diamond substrate was obtained without performing a grinding flattening process on the growth surface. The area of ​​this surface was 95% of the area of ​​the HPHT single-crystal diamond substrate. Furthermore, when the cross section of the cutting edge of Example 1 was observed with an optical microscope, the height difference 50 shown in Figure 6 was 0.05 mm.

[0094] The color of the deposited CVD single crystal diamond layer was visually confirmed to be "fancy yellow" in GIA grade, which was the same yellow color as the type Ib HPHT single crystal diamond substrate. -1Using the Raman spectrum as a standard, the full width at half maximum (FWHM) of the peak and the peak shift were calculated from the Raman spectrum. -1 The peak shift is +0.10cm -1 It was.

[0095] (3) Brazing process for bonding the blade tip The CVD single-crystalline diamond layer was then placed in a predetermined position on a base so that the two CVD single-crystalline diamond layers faced each other. Silver solder had been attached to the base in advance. The base on which the cutting edge was placed was then heated to 1000°C in air to melt the silver solder, and allowed to cool naturally to room temperature. The cutting edge was then attached to the base, yielding a cutting tool.

[0096] Example 2 CVD single-crystalline diamond was deposited on a pre-prepared Ib-type HPHT single-crystal diamond substrate (Element Chic, model number: MXP L3010) measuring 3 mm square and 1.0 mm thick, using a microwave plasma CVD apparatus. Hydrogen and methane were used as the main gases, and nitrogen was used as the additive gas. The hydrogen content was 100 parts by volume, and the methane content:nitrogen content was 5.0 parts by volume:0.05 parts by volume. The CVD single-crystalline diamond layer was deposited for 45 hours under deposition conditions of a temperature of 1000°C and a pressure of 100 torr. The "volume ratio (%) of methane to additive gas," calculated by dividing the additive gas content by the methane content and multiplying it by 100, was 1.00%.

[0097] For the next 5 hours, deposition was continued under deposition conditions of a temperature of 1000°C and a pressure of 100 torr, with the amount of hydrogen introduced being 100 parts by volume and the amount of methane introduced: nitrogen introduced = 5.0 parts by volume: 0.20 parts by volume, resulting in the deposition of a 0.6 mm thick CVD single crystalline diamond layer. The "volume ratio (%) of methane to added gas," calculated by dividing the amount of added gas introduced by the amount of methane introduced and multiplying this by 100, was 4.00%.

[0098] After deposition, the cutting edge was covered with DLC, which had large irregularities, so the DLC was removed by grinding in the same manner as in the past. In other words, in Example 2, after forming the CVD single-crystalline diamond layer 22, the abnormally grown areas were ground and flattened, as shown in Figure 6. As a result of this process, the area of ​​the surface parallel to the surface of the HPHT single-crystal diamond substrate 21 was 95% of the area of ​​the HPHT single-crystal diamond substrate 21. Furthermore, when the cross section of the cutting edge of Example 2 was observed with an optical microscope, the height difference 50 shown in Figure 6 was 0.06 mm.

[0099] The color of the deposited CVD single crystal diamond layer was observed by visual inspection of the cross section, and the color of the central part of the thickness of the CVD single crystal diamond layer was Fancy Light Yellow, and the color of the surface of the CVD single crystal diamond layer was Fancy Dark Yellow. -1 Using the Raman spectrum as a standard, the full width at half maximum (FWHM) of the peak and the peak shift were calculated. -1 The peak shift is +0.15cm -1 It was.

[0100] Figure 7 shows optical microscope photographs of the cutting edge of the cutting tool according to this embodiment, with Figure 7(a) being the HPHT single crystal diamond substrate before the CVD single crystal diamond layer was deposited in Example 2, and Figure 7(b) being the CVD single crystal diamond layer deposited on the HPHT single crystal diamond substrate in Example 2. It can be seen that the CVD single crystal diamond layer in Figure 7(b) is a darker colour (yellow) compared to the colour of the HPHT single crystal diamond substrate in Figure 7(a). The actual colour is as described above.

[0101] (3) Brazing process for bonding the blade tip The HPHT single crystal diamond substrate on which the CVD single crystal diamond layer was laminated was then machined into a predetermined shape, and the resulting cutting edge was placed in a predetermined position on a base so that the CVD single crystal diamond layer faced the base. Silver solder had been attached to the predetermined position on the base. The base on which the cutting edge was placed was then heated to 1000°C in air to melt the silver solder, and allowed to cool naturally to room temperature. The cutting edge was then attached to the base, resulting in a cutting tool.

[0102] 2. Example 3 A microwave plasma CVD apparatus was used with the same HPHT single crystal diamond substrate as in Example 2. Hydrogen and methane were used as the main gases, and nitrogen was used as the additive gas. The hydrogen introduction amount was 100 parts by volume, and the methane introduction amount: nitrogen introduction amount = 5.0 parts by volume: 0.10 parts by volume. Deposition was carried out for 40 hours under deposition conditions of a temperature of 1000°C and a pressure of 100 torr. The "volume ratio (%) of methane to additive gas," which is the ratio (%) obtained by dividing the amount of additive gas introduction by the amount of methane introduction and multiplying it by 100, was 2.00%.

[0103] For the next three hours, deposition was continued under deposition conditions of a temperature of 1000°C and a pressure of 100 torr, with the amount of methane introduced: the amount of nitrogen introduced = 5.0 volume parts:0.50 volume parts, resulting in the deposition of a 0.7 mm thick CVD single crystalline diamond layer. The "volume ratio (%) of methane to added gas," calculated by dividing the amount of added gas introduced by the amount of methane introduced and multiplying this by 100, was 10.00%.

[0104] In Example 3, as in Example 2, after deposition, the periphery of the cutting edge was covered with DLC that formed large irregularities, so the DLC was removed by grinding in the same manner as in the conventional method. That is, after forming the CVD single-crystalline diamond layer 22, Example 3 also underwent a process of grinding and flattening the abnormally grown areas, as shown in Figure 6. As a result of this process, the area of ​​the surface parallel to the surface of the HPHT single-crystalline diamond substrate 21 was 50% of the area of ​​the HPHT single-crystalline diamond substrate 21. Furthermore, when the cross section of the cutting edge of Example 3 was observed with an optical microscope, the height difference 50 shown in Figure 6 was 0.20 mm.

[0105] The color of the deposited CVD single crystal diamond layer was visually inspected on the cross section, and the color of the central part of the thickness of the CVD single crystal diamond layer was fancy yellow, and the color of the surface of the CVD single crystal diamond layer was fancy deep yellow. -1 Using the Raman spectrum as a standard, the full width at half maximum (FWHM) of the peak and the peak shift amount were calculated from the Raman spectrum. -1 The peak shift is +0.18 cm -1 It was.

[0106] In Examples 4 to 17, a CVD single crystalline diamond layer 22 was deposited on an HPHT single crystalline diamond substrate under the conditions shown in Table 1 below. Other conditions were the same as in Example 2, and cutting tools were manufactured using the same method. The colours of the CVD single crystalline diamonds are as shown in Table 1. Also in these Examples, the FWHM, which is the peak half width obtained from the Raman spectrum of the CVD single crystalline diamond layer 22, was 1.0 to 5.0 cm. -1 The peak shift amount of the CVD single crystalline diamond layer 22 was −1.0 to +1.0 cm -1 It was.

[0107] In Examples 4 to 17, after forming the CVD single-crystalline diamond layer 22, the abnormally grown areas were ground and flattened as shown in Figure 6. As a result of this process, the area of ​​the surface parallel to the surface of the HPHT single-crystalline diamond substrate 21 was 50 to 95% of the area of ​​the HPHT single-crystalline diamond substrate. Furthermore, when the cross section of the cutting edge was observed with an optical microscope, the height difference 50 shown in Figure 6 was 0.05 to 0.20 mm.

[0108] 5. Comparative Example 1 A cutting edge obtained under conditions in which the deposition conditions of the CVD single-crystalline diamond layer 22 in Example 1 were changed to those of Comparative Example 1 in Table 1 was placed at a predetermined position on a base so that the HPHT single-crystalline diamond substrate faced the base, and a bit tool was manufactured in the same manner as in Example 1.

[0109] 6. Comparative Example 2 A cutting tool was manufactured in the same manner as in Example 1, except that the CVD single-crystalline diamond layer was separated by laser cutting from the cutting edge obtained under the same deposition conditions as in Comparative Example 1, and the surface of the separated CVD single-crystalline diamond layer opposite to the separated surface was joined to a base. Examples and comparative examples including those mentioned above are as shown in Table 1 below.

[0110] 7. Evaluation The cutting tools of Examples 1 to 17 and Comparative Examples 1 and 2 obtained as described above were evaluated for (1) the height difference of the growth surface of the CVD single crystalline diamond layer, (2) the presence or absence of peeling of the cutting edge, and (3) substrate processing accuracy.

[0111] (1) Height difference of the growth surface of the CVD single-crystalline diamond layer The cross section of the cutting edge manufactured as described above was observed with an optical microscope, and the height difference was measured by depth measurement. The height difference was the difference between the lowest point and the highest point after the flat grinding process. If the height difference was less than 0.05 mm, it was evaluated as "poor," if the height difference was more than 0.05 mm but not more than 0.1 mm, it was evaluated as "good," and if the height difference was more than 0.1 mm, it was evaluated as "best."

[0112] (2) Presence or absence of peeling on the cutting edge After the above processing, it was visually checked whether the cutting edge had peeled off from the base. If no peeling of the cutting edge was observed, it was evaluated as "good", and if the cutting edge had peeled off, it was evaluated as "poor".

[0113] (3) Circuit board processing accuracy The Cu electrode on the Si substrate was ground using the cutting tool manufactured as described above. The ground surface was observed under an optical microscope. If no lines were present, it was evaluated as "good", and if lines were observed, it was evaluated as "poor". The evaluation results are shown in Table 1.

[0114] [Table 1]

[0115] As is clear from Table 1, all of the examples were rated "best" or "good." On the other hand, in Comparative Example 1, the HPHT single crystal diamond substrate and the base were bonded together, so the cutting edge had small irregularities and the cutting edge peeled off from the base. In Comparative Example 2, the CVD single crystal diamond layer was bonded to the base, so no peeling of the cutting edge was observed, but the processing accuracy was poor.

[0116] This example will be described using a photograph of the cutting edge manufactured by this example. Figure 8 is a photograph of the cutting edge of Example 2, which was deposited under the deposition conditions of the CVD single-crystalline diamond layer 22, with the amount of nitrogen introduced increased from 0.05 volume parts to 0.20 volume parts when the amount of hydrogen introduced was 100 volume parts, for the last 5 hours of the total deposition time; Figure 8(a) is an optical microscope photograph of the cutting edge, and Figure 8(b) is an SEM photograph of the cutting edge after grinding and flattening. Figure 9 is a photograph of the cutting edge of Example 3, which was deposited under the deposition conditions of the CVD single-crystalline diamond layer 22, with the amount of nitrogen introduced increased from 0.10 volume parts to 0.50 volume parts when the amount of hydrogen introduced was 100 volume parts, for the last 3 hours of the total deposition time; Figure 9(a) is an optical microscope photograph of the cutting edge, and Figure 9(b) is an SEM photograph of the cutting edge after grinding and flattening. Note that both Figure 8 and Figure 9 are photographs taken from the CVD single-crystalline diamond layer 22 side.

[0117] As shown in Example 2 in Figure 8, when the amount of nitrogen introduced during the 5 hours from the end of the deposition time (the last 10% of the process time of the CVD single-crystalline diamond layer deposition step, which is the second stage in Table 1) was increased from 0.05 volume parts in the first stage to 0.2 volume parts in the second stage, four times the amount of hydrogen introduced, assuming that the amount of hydrogen introduced was 100 volume parts, an in-plane height difference was formed on the surface of the CVD single-crystalline diamond layer 22. Also, in Example 2, as shown in Figure 8(b), in order to obtain a surface 22-4 parallel to the HPHT single-crystalline diamond substrate 21 in the CVD single-crystalline diamond layer 22, a grinding flattening treatment was performed over 95% of the area of ​​the CVD single-crystalline diamond layer 22. The height difference in Example 2 was 0.60 mm.

[0118] As shown in Example 3 in Figure 9, when the amount of nitrogen introduced during the three hours from the end of the deposition time (a time period of approximately 7% of the process time of the CVD single-crystalline diamond layer deposition step) was increased fivefold from 0.10 volume parts to 0.50 volume parts, assuming the amount of hydrogen introduced was 100 volume parts, the in-plane height difference of the upper surface of the cutting edge 20 was found to increase. Furthermore, in Example 2, in order to obtain a surface parallel to the HPHT single-crystalline diamond substrate 21 in the CVD single-crystalline diamond layer 22, it was necessary to perform grinding and flattening treatment over 95% of the area of ​​the CVD single-crystalline diamond layer. Furthermore, in Example 3, as shown in Figure 9(b), in order to obtain a surface 22-4 parallel to the HPHT single-crystalline diamond substrate 21 in the CVD single-crystalline diamond layer 22, grinding and flattening treatment was performed over 50% of the area of ​​the CVD single-crystalline diamond layer. Furthermore, the height difference after grinding and flattening treatment was 0.20 mm. [Explanation of symbols]

[0119] 1 Tool 10 Cutting edge 20 cutting edge 21 HPHT single crystal diamond substrate 22 CVD single-crystalline diamond layer 22-1 Recess 22-2 Convex area (abnormal growth area) 22-3 The outer part of the cutting edge 22-4 (HPHT single crystal diamond substrate) parallel surface 23 Brazing filler metal 30 Foundations 301 Mounting part 302 Tip mounting part 34 Shank 40 parallel lines (to the HPHT single crystal diamond substrate) 50 height difference [Industrial Applicability]

[0120] The cutting tool according to the present invention is widely used for superfinishing metal grinding, typically for aluminum, and is particularly suitable for planarizing and grinding composite semiconductor substrates for electrodes that form through-silicon vias (TSVs).

Claims

1. A tool having a base and a cutting edge brazed to the base, the cutting edge comprises a HPHT single crystal diamond substrate and a CVD single crystal diamond layer deposited on the HPHT single crystal diamond substrate; The cutting edge and the base are bonded together so that the CVD single-crystalline diamond layer of the cutting edge faces the base. A turning tool characterized by:

2. 2. The turning tool according to claim 1, wherein the thickness of the HPHT single crystal diamond substrate is 0.3 to 3.0 mm.

3. 3. The turning tool according to claim 1, wherein the thickness of the CVD single-crystalline diamond layer is 0.1 to 2.0 mm.

4. 3. The turning tool according to claim 1, wherein the CVD single-crystalline diamond layer is transparent or yellow in color.

5. 4. The turning tool according to claim 3, wherein the CVD single-crystalline diamond layer is transparent or yellow in color.

6. 3. The turning tool according to claim 1, wherein the near-surface region of the CVD single-crystalline diamond layer exhibits a color different from that of the region other than the near-surface region of the CVD single-crystalline diamond layer.

7. 4. The turning tool according to claim 3, wherein the near-surface region of the CVD single-crystalline diamond layer exhibits a color different from that of the region other than the near-surface region of the CVD single-crystalline diamond layer.

8. 5. The turning tool according to claim 4, wherein the near-surface region of the CVD single-crystalline diamond layer exhibits a color different from that of the region other than the near-surface region of the CVD single-crystalline diamond layer.

9. 6. The turning tool according to claim 5, wherein the near-surface region of the CVD single-crystalline diamond layer exhibits a color different from that of the region other than the near-surface region of the CVD single-crystalline diamond layer.

10. A manufacturing method of a cutting tool including a base and a cutting edge brazed to the base, a CVD single-crystalline diamond layer deposition step of depositing a CVD single-crystalline diamond layer on a pre-prepared HPHT single-crystalline diamond substrate by a CVD method in an atmosphere gas containing an additive gas composed of at least one of oxygen, nitrogen, and / or nitrogen oxides; a cutting edge bonding step of brazing the cutting edge formed by depositing the CVD single-crystalline diamond layer on the HPHT single-crystalline diamond substrate in the CVD single-crystalline diamond layer deposition step to the base so that the CVD single-crystalline diamond layer faces the base; A manufacturing method of a cutting tool, comprising:

11. 11. The method for manufacturing a cutting tool according to claim 10, wherein, during a time period from the last 20 to 0.5% of the process time of the CVD single-crystalline diamond layer deposition step onwards, the amount of added gas introduced is increased to 2 to 200 times the amount of added gas introduced during time periods other than said time period.

12. The method for manufacturing a turning tool according to claim 10, wherein the additive gas is introduced only during a time period from the last 20 to 0.5% of the process time of the CVD single-crystalline diamond layer deposition step onwards.

13. The method for manufacturing a turning tool according to any one of claims 10 to 12, further comprising a grinding and flattening step of grinding and flattening the deposition surface of the CVD single-crystalline diamond layer deposited in the CVD single-crystalline diamond layer deposition step so that the deposition surface is at least partially parallel to a surface of the HPHT single-crystalline diamond substrate.

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