WO2017077829A1 - Cubic boron nitride sintered body tool, cubic boron nitride sintered body used therein and production method for cubic boron nitride sintered body tool - Google Patents

Abstract

According to the present invention, a cubic boron nitride sintered body tool is provided with a tool base material, a bonding layer provided on a surface of the tool base material and a cubic boron nitride sintered body bonded to the tool base material via the bonding layer. The cubic boron nitride sintered body has bonding surfaces that are bonded to the bonding layer and an altered section including at least one substance selected from the group consisting of hexagonal boron nitride, boron, boron oxide and boron oxynitride exists on at least one of the bonding surfaces. The cubic boron nitride sintered body tool comprises the altered section having a thickness of 0.1-50.0 μm.

Description

Cubic boron nitride sintered body tool, cubic boron nitride sintered body used therefor, and method for producing cubic boron nitride sintered body tool

The present disclosure relates to a cubic boron nitride sintered body tool, a cubic boron nitride sintered body used therefor, and a method for manufacturing a cubic boron nitride sintered body tool. This application claims priority based on Japanese Patent Application No. 2015-217468 filed on November 5, 2015, and incorporates all the description content described in the above Japanese application.

Cubic boron nitride (cBN) sintered bodies are widely used as tools because of their excellent wear resistance and strength. A tool including a cBN sintered body (hereinafter referred to as “cBN sintered body tool”) generally has a structure in which a cBN sintered body is joined to a tool base material via a joining layer.

In such a cBN sintered body tool, if the bonding strength between the cBN sintered body and the tool base material is low, the cBN sintered body is dropped from the cBN sintered body tool during processing, and the function as a tool is achieved. It will not be satisfied. For this reason, in the cBN sintered body tool, it is important to increase the bonding strength between the cBN sintered body and the tool base material.

For example, Japanese Unexamined Patent Application Publication No. 2012-096934 (Patent Document 1) discloses that a cBN sintered body is provided with irregularities by removing a binder phase contained in the cBN sintered body from the surface of the cBN sintered body. A technique for increasing the bonding strength between the cBN sintered body and the tool base material by the uneven anchor effect is disclosed.

JP 2012-096934 A

A cBN sintered body tool of the present disclosure includes a tool base material, a joining layer provided on the surface of the tool base material, and a cBN sintered body joined to the tool base material via the joining layer, and cBN. The sintered body has a bonding surface to be bonded to the bonding layer, and at least one of the bonding surfaces has hexagonal boron nitride (hBN), boron (B) (hereinafter referred to as “boron” or “B”). ”Means boron alone, does not include boron constituting a compound with other elements), boron oxide (B ₂ O ₃ ), and boron oxynitride (B ₂ ON ₃ ) There is an altered portion containing at least one selected from the group consisting of, and the altered portion has a thickness of 0.1 μm or more and 50.0 μm or less.

The cBN sintered body of the present disclosure is a cBN sintered body used for the cBN sintered body tool.
A method of manufacturing a cBN sintered body tool of the present disclosure includes a tool base material, a bonding layer provided on the surface of the tool base material, and a cBN sintered body bonded to the tool base material via the bonding layer. A method of manufacturing a cBN sintered body tool comprising a step of sintering boron nitride (BN) particles to produce a cBN sintered body, a step of laser processing the cBN sintered body with a pulse laser, and a laser Bonding the processed cBN sintered body to a tool base material via a bonding layer, the pulse energy in the pulse laser is 0.01 J or more and 1.5 J or less, and the pulse width is 0.01 msec or more The output is 0.40 msec or less, and the output is 30 W or more and 500 W or less.

FIG. 1 is a plan view showing an example of a cBN sintered body tool according to the first embodiment. FIG. 2 is a front view of the cBN sintered body tool of FIG. FIG. 3 is a partially enlarged view of the cBN sintered body tool of FIG. FIG. 4A is a schematic view showing a state in which the mixed powder is arranged on the support plate. FIG. 4B is a schematic view showing a laminate composed of a support plate and a cBN sintered body. FIG. 4C is a schematic view showing a state where the support plate is removed from the laminate. FIG. 4D is a schematic view showing a state where the cBN sintered body is laser processed. FIG. 5A is a diagram schematically showing a workpiece before being processed by a pulse laser. FIG. 5B is a diagram schematically showing the workpiece after being processed by the pulse laser. FIG. 6 is a plan view showing an example of a cBN sintered body tool according to the second embodiment. FIG. 7A is a plan view schematically showing an outline of how to apply the punching bar when measuring the bonding strength of the cBN sintered body tool. FIG. 7B is a front view schematically showing an outline of how to apply the punching bar when measuring the bonding strength of the cBN sintered body tool.

[Problems to be solved by this disclosure]
In order to prevent the above-described dropout under severe use conditions that satisfy recent market demands, it is required to further increase the bonding strength between the cBN sintered body and the tool base material.

An object of the present disclosure is to provide a cBN sintered body tool in which a cBN sintered body is firmly bonded.
[Effects of the present disclosure]
According to the present disclosure, it is possible to provide a cBN sintered body tool in which a cBN sintered body is firmly bonded.

[Description of Embodiment]
First, embodiments of the present invention will be listed and described.

[1] A cBN sintered body tool of the present disclosure includes a tool base material, a joining layer provided on the surface of the tool base material, and a cBN sintered body joined to the tool base material via the joining layer. The cBN sintered body has a bonding surface to be bonded to the bonding layer, and at least one surface side of the bonding surface is made of hBN, B, B ₂ O ₃ , and B ₂ ON ₃ There is an altered portion including at least one selected, and the altered portion has a thickness of 0.1 μm or more and 50.0 μm or less.

According to the cBN sintered body tool, the tool base material and the cBN sintered body are firmly bonded to each other and the damage due to the presence of the altered portion is suppressed by providing the altered portion as described above. Can do. Thereby, as for the said cBN sintered compact tool, a cBN sintered compact will be joined firmly.

[2] In the cBN sintered body tool, the altered portion preferably has a thickness of 0.3 μm or more and 5.0 μm or less. Thereby, the joint strength of a cBN sintered compact and a joining layer can be raised.

[3] In the cBN sintered body tool, the cBN content in the cBN sintered body is preferably 80.0% by volume or more. Thereby, the joint strength of a cBN sintered compact and a joining layer can be raised.

[4] In the cBN sintered body tool, the cBN content in the cBN sintered body is preferably 96.0% by volume or more. Thereby, the joint strength between the cBN sintered body and the joining layer can be further increased.

[5] In the above cBN sintered body tool, it is preferable that an angle formed by two joining surfaces intersecting each other among the joining surfaces is 89.0 ° or more and 91.0 ° or less. Thereby, a cBN sintered compact and a tool base material are joined more firmly.

[6] In the above cBN sintered body tool, the thermal conductivity of the cBN sintered body is preferably 70 W / m · K or more. In a cBN sintered body having such a thermal conductivity, the presence of an altered portion having an excessively large thickness is easily suppressed, and as a result, the bonding strength between the cBN sintered body and the bonding layer can be increased. it can.

[7] The cBN sintered body of the present disclosure is a cBN sintered body used for the cBN sintered body tool.

According to the cBN sintered body, a cBN sintered body tool in which the cBN sintered body is firmly joined can be provided by being used for a cBN sintered body tool.

[8] A method for manufacturing a cBN sintered body tool of the present disclosure includes a tool base material, a joining layer provided on the surface of the tool base material, and a cBN sintered body joined to the tool base material via the joining layer. A method of manufacturing a cBN sintered body tool comprising: a step of sintering a BN particle to produce a cBN sintered body; a step of laser processing the cBN sintered body with a pulse laser; and a laser processing Bonding the cBN sintered body to the tool base material via a bonding layer, the pulse energy in the pulse laser is 0.01 J or more and 1.5 J or less, and the pulse width is 0.01 msec or more and 0 .40 msec or less, and output is 30 W or more and 500 W or less.

According to the method for producing a cBN sintered body, the altered portion having a thickness of 0.1 μm or more and 50.0 μm or less is generated on the processed surface formed by the pulse laser. The above-mentioned cBN sintered body tool in which the bonded body is firmly bonded can be manufactured.

In the above method for producing a cBN sintered body, the pulse laser is preferably a fiber laser. This is because the processed surface formed by the fiber laser has excellent bonding strength with the bonding layer.

[Details of the embodiment]
Hereinafter, although embodiment of this indication is described, this embodiment is not limited to these. In the present specification, the notation in the form of “A to B” means the upper and lower limits of the range (that is, A or more and B or less), the unit is not described in A, and the unit is described only in B. The unit of A is the same as the unit of B.

[First Embodiment]
[CBN sintered body tool]
FIG. 1 is a plan view showing an example of a cBN sintered body tool according to this embodiment, and FIG. 2 is a front view of the cBN sintered body tool of FIG. As shown in FIGS. 1 and 2, the cBN sintered body tool 10 includes a tool base material 1, a joining layer 2 provided on the surface of the tool base material 1, and a tool base material 1 via the joining layer 2. And a cBN sintered body 3 joined to each other.

Such a cBN sintered body tool 10 can be used in various kinds of processing of general metals, and can be effectively used particularly in machining of sintered alloys, hard-to-cut cast iron, hardened steel, and heat-resistant alloys.

When the cBN sintered body tool 10 is used for cutting applications, for example, drill, end mill, milling or turning cutting edge replacement cutting tip, metal saw, gear cutting tool, reamer, tap, or crankshaft pin milling It can be effectively used as a chip for use.

When the cBN sintered body tool 10 is used for plastic working, it can be effectively used as, for example, a punch press die, a die for die, friction welding, or the like. Further, engine parts, hard disk drives (HDD), HDD heads, capstans, wafer chuck semiconductor transfer arms, camera zoom lens seal rings, friction stir welding tools, and the like can be exemplified.

Note that “cutting” refers to machining a product having a desired size and shape while scraping off chips, and “plastic processing” refers to applying a force to the workpiece to deform the desired size and shape. This means that the product is processed. Plastic processing differs from cutting in that no chips are generated.

(Tool base material)
The material of the tool base material 1 is not particularly limited as long as it is a conventionally known material used as this kind of tool base material. For example, a material that can withstand the processing resistance, such as cemented carbide, steel, ceramics, and the like can be suitably used. Among these, cemented carbide is preferable from the viewpoint of strength.

The shape of the tool base material 1 is not particularly limited as long as it is a conventionally known shape used as this kind of tool base material. In the present embodiment, as shown in FIGS. 1 and 2, a tool base having a shape having two surfaces (surface 1 a and surface 1 b) as surfaces to which the cBN sintered body 3 is bonded via the bonding layer 2. The material 1 will be described.

(Junction layer)
The joining layer 2 plays a role for joining the tool base material 1 and the cBN sintered body 3. The bonding layer 2 of the present embodiment is provided on the surface 1 a and the surface 1 b of the tool base material 1. As long as the tool base material 1 can play the role, the material is not particularly limited. For example, the following (1) or (2) bonding layer can be used.

(1) A bonding layer containing 5% by mass or more of Ti and 5% by mass or more of Zr with respect to the entire bonding layer, the total of Ti and Zr being 90% by mass or less, and the balance being Cu. ;
(2) A bonding layer containing 1% by mass or more of Ti and 15% by mass or more of Cu with respect to the entire bonding layer, and the remainder including Ag.

When the bonding layer (1) is used as the bonding layer 2, the bonding layer 2 can exhibit high high temperature resistance and high wettability due to the presence of Ti and Zr. Bonding strength with the cBN sintered body 3 can be increased. Also, due to the presence of Cu, joining at a low temperature is possible, and due to the high elastic modulus of Cu, when heat generated during processing flows into the tool base material 1 through the cBN sintered body 3. Further, the bonding layer 2 can relieve the distortion caused by the difference between the thermal expansion coefficient of the cBN sintered body 3 and the thermal expansion coefficient of the tool base material 1. Even when the bonding layer (2) is used as the bonding layer 2, the same effect as described above can be obtained.

Further, it is preferable that 5% by mass or more of Ni is mixed in the bonding layer (1) and the bonding layer (2). In this case, since the wettability of the bonding layer 2 with respect to the cBN sintered body 3 can be further improved, the bonding strength between the cBN sintered body 3 and the bonding layer 2 is further improved.

The thickness of the bonding layer 2 is preferably 10 μm or more. When the thickness of the bonding layer 2 is less than 10 μm, the bonding force of the bonding layer 2 may be easily reduced. The thickness of the bonding layer 2 is preferably 200 μm or less. Usually, since the hardness of the bonding layer 2 tends to be lower than the hardness of the tool base material 1 and the cBN sintered body 3, if the thickness exceeds 200 μm, the bonding layer 2 itself may be damaged. .

[CBN sintered body]
The cBN sintered body 3 is joined to the tool base material 1 via the joining layer 2. As shown in FIGS. 1 and 2, the cBN sintered body 3 of the present embodiment has two bonding surfaces 3 a and 3 b as bonding surfaces to be bonded to the bonding layer 2, and two bonding surfaces 3 a. , 3b intersect with each other to form a ridgeline 3c.

The cBN sintered body 3 includes crystal grains (cBN crystal grains) made of cBN. The particle size of the cBN crystal grains is not particularly limited, but can be 0.1 to 10 μm from the viewpoint of increasing the hardness. The cBN sintered body may be composed only of cBN crystal grains, and may contain other components.

As a component other than the above cBN crystal grains, a binder phase can be mentioned. The binder phase has a role of binding the cBN particles, and the material is not particularly limited as long as it can have the role. For example, the following (3) or (4) can be used as the binder phase contained in the cBN sintered body 3.

(3) consisting of at least one element selected from the group consisting of Group 4 to 6 elements of the periodic table and at least one element selected from the group consisting of N, C, B, and O A bonded phase comprising a compound or a solid solution of the compound and an Al compound (AlN, AlB ₂ , Al ₂ O _3, etc.);
(4) From a compound selected from the group consisting of Al compound, cobalt (Co), W compound (WC, W ₂ Co ₂₁ B ₆ , Co ₃ W ₃ C, W ₃ CoB _3, etc.), or a solid solution of the compound A bonded phase.

In the cBN sintered body 3, when a binder phase such as the above (3) and (4) is present, particularly excellent wear resistance is exhibited in machining of sintered alloys, cast iron, hardened steel, heat-resistant alloys and the like. be able to.

Further, as components other than cBN crystal grains, BN having a crystal structure other than cBN, for example, boron nitride (wBN) having a wurtzite crystal structure, boron nitride having a compressive hexagonal crystal structure (compressed BN), etc. (However, hBN is not included in “BN having a crystal structure other than cBN”).

When the above-mentioned binder phase is contained in the cBN sintered body 3, the binder phase is preferably contained in an amount of at least 3% by volume in order to exhibit the effect of bonding the cBN crystal grains. On the other hand, when the cBN sintered body 3 does not include a binder phase, the content ratio of the cBN particles in the cBN sintered body 3 is 98% by volume or more. That is, the total content of wBN and compressed BN that can be included in the cBN sintered body 3 that does not include a binder phase is less than 2% by volume. This is because wBN and compression-type BN are produced (remaining) in the cBN sintered body 3 in the production process when producing a cBN sintered body that does not contain a binder phase. This is because there is an upper limit for the residual ratio.

The above-mentioned cBN sintered body 3 may contain inevitable impurities such as nitrogen (N), hydrogen (H), oxygen (O). In addition, when the cBN sintered body 3 includes a binder phase, impurities such as cemented carbide, silicon nitride, zirconia, and alumina may be included in the manufacturing process. In the cBN sintered body 3, the content of each component that is an unavoidable impurity is less than 4%, and the content of each component that is an impurity is less than 3%.

[Changed part]
Furthermore, in the cBN sintered body 3 described above, an altered portion exists on at least one of the joint surfaces 3a and 3b. In the present embodiment, the case where the altered portion exists only on the joint surface 3a side will be described with reference to FIGS.

As shown in FIGS. 2 and 3, the surface of the cBN sintered body 3 is composed of hBN, B, B ₂ O ₃ , and B ₂ ON ₃ on the side of the bonding surface 3 a that is bonded to the bonding layer 2. An altered portion 31 including at least one selected from the group is present. The hBN is generated by the phase transformation of cBN located on the surface of the cBN sintered body by a processing step described later. B is generated by denitrification of cBN by a processing step described later. B ₂ O ₃ and B ₂ ON ₃ are produced by oxidizing B or BN _x (x <1) obtained by denitrifying all or part of nitrogen of cBN by a processing step described later. is there.

That is, at least one selected from the group consisting of hBN, B, B ₂ O ₃ , and B ₂ ON ₃ and cBN exist in the region of the altered portion 31 in the cBN sintered body 3. In the case where the cBN sintered body 3 includes a binder phase, the region of the altered portion 31 may further include a binder phase, and the cBN sintered body 3 includes wBN and / or compressed BN. In this case, the region of the altered portion 31 may further include wBN and / or compressed BN.

Here, in the cBN sintered body 3, the altered portion 31 and the region other than the altered portion 31 are distinguished as follows. Hereinafter, a region other than the altered portion 31 in the cBN sintered body 3 is referred to as a base 32.

First, CP processing is performed on a surface of the cBN sintered body 31 in which the configuration in the thickness direction of the bonding surface 3a is observed using a cross section polisher (CP). As such a surface, the surface shown by FIG. 2 and FIG. 3 is mentioned. The CP processing conditions are as follows. When the thickness direction (depth direction) of the bonding surface 3a is not visible, the cBN sintered body is cut at a plane including the normal of the surface of the bonding surface 3a, and the appearing cross section is subjected to CP processing. May be.

(CP processing conditions)
Pressurization speed: 6kV
Irradiation current: 0.30 mA
Irradiation time: 300 minutes.

Next, the components of the cBN sintered body are analyzed by observing the CP processed surface by various analysis methods. Specifically, whether or not at least one of hBN, B ₂ O ₃ , and B ₂ ON ₃ is present in the cBN sintered body by performing Raman spectroscopic analysis using a Raman spectroscopic device. Is confirmed. Also, by performing energy dispersive X-ray analysis (EDS analysis) or Auger electron spectroscopy (AES method) using an energy dispersive X-ray analyzer, whether or not B is present in the cBN sintered body is determined. It is confirmed. Then, the region in which hBN, B ₂ O ₃ , or B ₂ ON ₃ is considered to exist and / or the region in which B is considered to exist is regarded as the altered portion 31.

In Raman spectroscopic analysis (observation area of 1 μm × 1 μm), an area where 5% by volume or more of hBN, B ₂ O ₃ , or B ₂ ON ₃ is observed with respect to cBN is defined as an area where each component exists. I reckon. Further, in the EDS analysis (observation region of 2 μm × 2 μm), a region where the ratio of B element is 95 atm% or more is regarded as a region where B exists. Alternatively, in the AES method (observation region of 0.2 μm × 0.2 μm), a region where the ratio of B element is 95 atm% or more is regarded as a region where B exists. However, in the AES method, the ratio of B element is calculated after correcting (excluding) C and O adsorbed on the surface of the observation region. As a device used for the AES method, “PHI700” (manufactured by ULVAC-PHI Co., Ltd.) can be used.

The altered portion 31 has a thickness d of 0.1 to 50.0 μm. When the altered portion 31 includes at least one selected from the group consisting of hBN, B ₂ O ₃ , and B ₂ ON ₃ , the thickness d can be confirmed by Raman spectroscopy. For example, the surface of the cBN sintered body 3 shown on the paper surface in FIG. 2 is observed with a Raman spectroscope, and the region where hBN, B ₂ O ₃ , or B ₂ ON ₃ exists is specified. And in the said area | region, from the position of the outermost surface of the joining surface 3a which contacts the joining layer 2, the position (from joining surface 3a) is the innermost side among the areas where hBN, B ₂ O ₃ or B ₂ ON ₃ exists The shortest distance to the deepest position is “thickness d”.

Further, when B is included in the altered portion 31, the thickness d can be confirmed by an EDS analysis method. For example, the surface of the cBN sintered body 3 shown on the paper surface in FIG. 2 is analyzed by EDS to identify the region where B exists. In the region, the shortest distance from the position of the bonding surface 3a in contact with the bonding layer 2 to the innermost position in the region where B exists is “thickness d”.

Therefore, in order to actually determine the thickness d, the region where each component of hBN, B, B ₂ O ₃ , or B ₂ ON ₃ is present is identified and identified by Raman spectroscopic analysis and EDS analysis. Among the regions, it is necessary to determine the shortest distance from the position of the joint surface 3b to the region located at the innermost position.

[Method of manufacturing cBN sintered body tool]
A method of manufacturing a cBN sintered body tool according to this embodiment will be described with reference to FIGS. 4A to 4D. Here, the case where a binder phase is included in the cBN sintered body will be described.

[Crushing process]
First, a raw material powder for a binder phase is prepared by this step. For example, when TiN, AlN, TiAlN or the like is used as the binder phase, TiN powder and Al powder are prepared, a mixed powder thereof is prepared, and the mixed powder is pulverized using a ball mill. Thereby, the raw material powder for binder phases is produced.

Examples of the ball mill material include cemented carbide, silicon nitride, zirconia, and alumina. When a cBN sintered body including a binder phase is produced, impurities such as the above cemented carbide, silicon nitride, zirconia, and alumina may be mixed in the raw powder of the binder phase due to this pulverization process. .

[Sintering process]
Next, the produced raw material powder for binder phase and cBN powder (boron nitride particles) are mixed to prepare a mixed powder 41. As shown in FIG. 4A, this mixed powder 41 is supported by a cemented carbide. It arrange | positions on the board 42 and shape | molds. And this is introduce | transduced into an ultra-high pressure apparatus, and is sintered by ultra-high pressure. The ultrahigh pressure sintering conditions are as follows.

(Sintering conditions)
Pressure: 3-7GPa
Temperature: 1100-1900 ° C
Time: 10-180 minutes.

As a result, as shown in FIG. 4B, a cBN sintered body composed of a binder phase and cBN particles is formed on the support plate, and thus the support plate 42 is attached to one surface (one surface) of the cBN sintered body 3A. A laminated body is produced. In the present embodiment, by further removing all of the support plate 42 from the laminate, a cBN sintered body 3A is produced as shown in FIG. 4C. The method for removing the support plate 42 is not particularly limited, and examples thereof include grinding removal. The cBN sintered body 3A may contain inevitable impurities and impurities.

[Processing process]
Next, the produced cBN sintered body 3A is processed by a pulse laser. Specifically, after forming the cBN sintered body 3A into a plate shape, the plate-like sintered body is set in a pulse laser device, and the plate-like sintered body is laser processed into a desired shape. As shown in 4D, a laser-processed cBN sintered body 3B is obtained. The pulse energy in the pulse laser is 0.01 J or more and 1.5 J or less, the pulse width is 0.01 msec or more and 0.40 msec or less, and the output is 30 W or more and 500 W or less. Below, the suitable processing conditions A of the pulse laser including these conditions are shown.

(Processing condition A)
Pulse energy: 0.01-1.5J
Pulse width: 0.01-0.40 msec
Output: 30-500W
Frequency: 100-2000Hz
Wavelength: 1070 nm.

In the laser-processed cBN sintered body 3B, a modified portion 31 is formed on a processed surface processed by a pulse laser. This is because the cBN sintered body is processed by heat in the processing under the above conditions, so that a part of cBN located on the processing surface is transformed into hBN, or all or one part of cBN positioned on the processing surface. This is because B or BN _x (x <1) formed by denitrifying a part of nitrogen is oxidized.

[Jointing process]
Next, the laser-processed cBN sintered body 3 </ b> B is bonded to the tool base material 1 through the bonding layer 2. Specifically, first, a material that is a raw material of the bonding layer 2 is sandwiched between the laser-processed cBN sintered body 3 </ b> B and the tool base material 1. At this time, the respective members are arranged so that the surface 1a of the tool base material 1 faces the processed surface of the cBN sintered body 3B (that is, the surface where the altered portion 31 exists, and in this embodiment, the joint surface 3a). Let

Next, the laminated body in which the material constituting the bonding layer 2 is sandwiched between the laser-processed cBN sintered body 3B and the tool base material 1 is placed in a vacuum furnace. And while reducing the pressure in a vacuum furnace to 2 * 10 ^<-2 > Pa or less, and making the temperature in a furnace into 750 degreeC or more, the material which comprises the joining layer 2 is dissolved. As a result, the laser-processed cBN sintered body 3B and the tool base material 1 are joined. Next, the material which comprises the joining layer 2 is solidified by taking out the joined processed material from a vacuum furnace and allowing it to cool. Then, by polishing the outer periphery of the joint surface between the cBN sintered body 3B and the joint layer 2 and the outer periphery of the joint surface between the tool base material 1 and the joint layer 2, the periphery of the joint surface (the cBN sintered body tool 10) is polished. The portion exposed as the outer surface of the surface is smoothed. As described above, the cBN sintered body tool 10 in which the cBN sintered body 3 and the tool base material 1 are bonded via the bonding layer 2 is produced.

In the case where an altered portion is also present on the surface of the cBN sintered body 3 corresponding to a surface that is easy to escape, the altered portion is polished by polishing the portion where the altered portion is present during the above polishing process. It is preferable to remove. This is because the altered portion has an effect of improving the bonding strength between the cBN sintered body 3 and the tool base material 1, but tends to have lower hardness than the base 32.

In the manufacturing method described above, the case where the cBN sintered body tool 10 including the binder phase (3) or (4) is manufactured has been described. However, the pulverization step of the manufacturing method is not performed, and the sintering step is performed. Can be manufactured as follows, and the cBN sintered compact tool 10 which does not contain a binder phase can be manufactured.

First, as BN particles, a powder made of atmospheric pressure type BN such as hBN or pyrolytic boron nitride (pBN) is introduced into an ultrahigh pressure apparatus. Then, this powder is subjected to ultra-high pressure sintering. The ultrahigh pressure sintering conditions are as follows. Thereby, most (98% or more) of the normal pressure type BN is converted to cBN, and as a result, a cBN sintered body containing no binder phase is produced. This cBN sintered body may contain 2% by volume or less of BN (wBN and / or compressed BN) having a crystal structure other than cBN.

(Sintering conditions)
Pressure: 8-20GPa
Temperature: 1300-2300 ° C
Time: 5-30 minutes.

When manufacturing the cBN sintered compact tool 10 which does not contain a binder phase, the relationship between the pressure and temperature in an ultrahigh pressure sintering condition becomes important. For example, when the pressure is about 10 GPa, the temperature is preferably about 1900 to 2300 ° C., and when the pressure is about 20 GPa, the temperature can be about 1300 to 1900 ° C.

In addition, when hBN is used as the normal pressure type BN, it is preferable to use highly crystalline hBN from the viewpoint of increasing the hardness. The highly crystalline hBN means that the graphitization index (GI value) in the X-ray diffraction method is less than 5. The GI value is a value derived by introducing the areas of the three peaks of x-ray diffraction of hBN, that is, the peaks of (100), (101), and (102) into the following formula (1). The smaller the performance, the smaller.
GI = (I ₍₁₀₀₎ + I ₍₁₀₁₎ ) / I ₍₁₀₂₎ Expression (1).

On the other hand, when pBN is used as the normal pressure BN, it is preferable to use pBN having orientation from the viewpoint of increasing hardness. For example, pBN may have an orientation on the (002) plane, and (010) plane X-rays with respect to the X-ray diffraction intensity of the (002) plane of pBN when pBN is diffracted from the c-axis direction. The ratio of diffraction intensities may be 0.1 or less. As long as pBN has such orientation, a commercially available product can be used.

〔effect〕
The effects of the cBN sintered body tool 10 according to the present embodiment will be described in comparison with the prior art.

According to the technique disclosed in Patent Document 1, by removing the binder phase from the surface of the cBN sintered body, unevenness is provided on the surface of the cBN sintered body, and the cBN sintered body and the tool are provided by the anchor effect of the unevenness. Bonding strength with the base material is increased. However, in this technique, it is required to set the content ratio of cBN in the cBN sintered body to be relatively low in order to appropriately provide unevenness on the surface of the cBN sintered body.

On the other hand, according to the cBN sintered body tool 10 according to the present embodiment, the altered portion 31 having a thickness d of 0.1 to 50.0 μm is present on the surface of the cBN sintered body 3. The bonding strength between the sintered body 3 and the tool base material 1 is increased. Therefore, since there is no restriction like the above technique, it can be applied to a tool having a wide composition. The present inventors infer the reason why the bonding strength between the cBN sintered body 3 and the tool base material 1 is increased in the cBN sintered body tool 10 according to the present embodiment as follows.

The wettability of hBN, B, B ₂ O ₃ , and B ₂ ON ₃ present in the altered portion 31 is higher than that of cBN. For this reason, since both are joined in a state in which the bonding layer 2 corresponds (along) to the fine irregularities on the surface of the cBN sintered body, the cBN sintered body and the tool base material 1 that do not have the altered portion 31. And the case where the cBN sintered body 3 having the altered portion 31 and the tool base material 1 are joined via the joining layer 2 than the case where they are joined via the joining layer 2. And the contact area between the bonding layer 2 are increased. Since the bonding strength between the two members increases as the contact area increases, the cBN sintered body tool 10 according to the present embodiment has a bonding strength between the cBN sintered body 3 and the tool base material 1 as compared with the conventional case. Get higher. Here, “wetability” means wettability with respect to a melt in which a material for forming the bonding layer 2 is dissolved.

On the other hand, when the thickness d of the altered portion 31 is less than 0.1 μm, the thickness is too thin, so that the above-described effect due to high wettability such as hBN cannot be exhibited appropriately. When the thickness d exceeds 50.0 μm, the altered portion 31 itself becomes a starting point of breakage or destruction. The thickness d is preferably 0.3 to 5.0 μm.

In the cBN sintered body tool 10 according to the present embodiment, it is preferable that at least one of hBN and B exists in the altered portion 31. In this case, the bonding strength tends to be further increased. The reason for this is as follows.

That is, in order to manufacture a cBN sintered body tool including a tool base material, a bonding layer, and a cBN sintered body, it is necessary to perform at least the above-described bonding process, and in the bonding process, the bonding process is performed. The workpiece is allowed to cool. However, since the thermal expansion coefficient of the bonding layer 2 tends to be higher than the thermal expansion coefficient of cBN, the bonding layer 2 contracts greatly compared to cBN when allowed to cool. For this reason, in a conventional cBN sintered body tool (that is, a cBN sintered body tool in which the substrate 32 and the bonding layer 2 are in contact), a relatively large internal stress due to the difference in thermal expansion coefficient as described above remains. There was a trend. Such internal stress can be a factor that causes the cBN sintered body to fall off from the cBN sintered body tool.

On the other hand, since hBN and B have a thermal expansion coefficient larger than that of cBN, the altered portion 31 including at least one of hBN and B is present between the base body 32 and the bonding layer 2. The difference in thermal expansion coefficient can be reduced. Therefore, according to the cBN sintered body tool 10 having the altered portion 31 including at least one of hBN and B, the internal stress can be relaxed (reduced) compared to the conventional case. As compared with the above, the bonding strength between the cBN sintered body 3 and the tool base material 1 is increased.

More preferably, of hBN, B, B ₂ O ₃ , and B ₂ ON ₃ , it is preferable that only hBN exists in the altered portion 31. This is because hBN is most excellent in terms of the above-described wettability and thermal expansion coefficient.

Further, the content ratio of the cBN particles in the cBN sintered body 3 is preferably 80.0% by volume or more, more preferably 96.0% by volume or more. In this case, the bonding strength between the cBN sintered body 3 and the tool base material 1 can be increased. Further, such a high content ratio of cBN particles tends to be difficult with the technique disclosed in Patent Document 1, but according to the present embodiment, this is possible.

Here, in the cBN sintered body 3, the content ratio of the cBN particles in the base body 32 and the content ratio of the cBN particles in the altered portion 31 are different, but the content ratio of the cBN particles in the entire cBN sintered body 3 is in the above range. If it exists, there can exist said effect.

In addition, when the cBN sintered body 3 includes a binder phase, the content ratio of the binder phase is preferably 4 to 97% by volume, and more preferably 4 to 39% by volume. When the cBN sintered body 3 does not contain a binder phase, the content ratio of cBN particles is preferably 98 to 100% by volume. In this case, the cBN sintered body 3 is excellent in the balance between the bonding strength between the cBN particles and the hardness of the cBN sintered body 3.

The thermal conductivity of the cBN sintered body 3 is preferably 70 W / m · K or more. In this case, the thickness d of the altered portion 31 can be easily controlled within the above range, and the thickness d of the altered portion 31 tends to be uniform. This is because, when the thermal conductivity of the cBN sintered body 3 is 70 W / m · K or more, heat retention on the surface of the bulk sintered body hardly occurs during pulse laser processing. This is thought to be due to the suppression of excessive spread (promotion).

The thermal conductivity of the cBN sintered body 3 is more preferably 85 W / m · K or more, further preferably 100 W / m · K or more, and particularly preferably 120 W / m · K or more. The thermal conductivity of the cBN sintered body 3 is preferably 2000 W / m · K or less. This is because, when it exceeds 2000 W / m · K, the speed at which heat is transmitted is too high, and the altered portion 31 having a sufficient thickness tends not to be formed.

The thermal conductivity of the cBN sintered body 3 can be obtained by a laser flash method in accordance with “JIS R1611: 2010”. Specifically, after a sample for a measurement sample is cut out from the cBN sintered body 3, a processed surface by a pulse laser is polished and removed to produce a measurement sample for thermal conductivity having a diameter of 18 mm and a thickness of 1 mm. And a pulse laser beam is irradiated with respect to a measurement sample using a thermal constant measuring apparatus, and the specific heat and thermal diffusivity of a measurement sample are measured. The thermal conductivity of the cBN sintered body 3 is calculated by multiplying the thermal diffusivity by the specific heat and the density of the cBN sintered body.

The measurement sample produced from the cBN sintered body 3 hits the base 32 portion of the cBN sintered body, and the altered portion 31 does not exist. Therefore, in this specification, “the thermal conductivity of the cBN sintered body 3” corresponds to “the thermal conductivity of the substrate 32 constituting the cBN sintered body 3”.

The cBN sintered body 3 according to the present embodiment is manufactured for the first time by a manufacturing method using a pulse laser as described above. This is because, by the above-described processing steps, the above-described modified portion 31 is generated for the first time when the cBN on the surface of the cBN sintered body is thermally altered to an appropriate ratio and to an appropriate depth. is there.

On the other hand, the present inventors have confirmed that when the cBN sintered body is processed by a wire saw, wire electric discharge machining (WEDM) or the like, the above-described altered portion is not formed. Further, the processed surface is rough as compared with the case of a pulse laser, and there is a tendency that microcracks, chips, and the like exist.

The pulsed laser, a fiber laser in which the optical fiber and the amplifying medium, YAG laser was YAG amplification medium, such as CO ₂ laser in which the CO ₂ and the amplifying medium and the like. Further, processing methods using a pulse laser are classified into thermal processing and non-thermal processing depending on the difference in laser wavelength and pulse width. In thermal processing, laser light is converted into heat absorbed by the surface of the material, and the material is processed while the material is melted by that heat. In non-thermal processing, laser light is absorbed. The material is processed while breaking the bonds between the atoms or molecules at the locations and instantaneously evaporating the material in the atomic or molecular state.

In the execution of the processing step of the present embodiment, thermal processing using a fiber laser or YAG laser is preferable. When a processing step is carried out using these, it becomes possible to satisfy the above-mentioned preferable processing conditions. Among these, it is preferable to use a fiber laser. Compared with the YAG laser processed surface, the processed surface by the fiber laser has a reduced thickness, and the generation of microcracks is particularly suppressed. Therefore, the bonding strength between the cBN sintered body and the tool base material 1 is reduced. It is because it is excellent in.

Regarding the processing condition A, the pulse energy is preferably 0.01 to 1.5 J, and the pulse width is preferably 0.01 to 0.40 msec. In this case, the altered portion 31 is further appropriately formed.

In addition to the above processing condition A, it is preferable to use a pulse laser that satisfies the following specifications. In this case, since the thickness of the joining layer 2 can be made uniform, the stress applied to the joining surface during the joining process becomes uniform, and as a result, the joining strength between the tool base material 1 and the cBN sintered body 3 is further increased. Can be increased. In particular, the fiber laser easily satisfies the following specifications.

(Laser oscillator and processing machine specifications)
Laser spread angle: 2.0 mm / mrad or less Spot diameter: 15 μm or less.

The reason why the bonding strength is further increased when the processing condition A is satisfied will be described with reference to FIGS. 5A and 5B. FIG. 5A is a diagram schematically showing a workpiece before being processed by the pulse laser, and FIG. 5B is a diagram schematically showing the workpiece after being processed by the pulse laser. The arrows in FIG. 5A indicate the direction of the laser irradiated on the rectangular parallelepiped workpiece 20.

When a rectangular parallelepiped (plate-like) work piece 20 as shown in FIG. 5A is prepared, and this is to be cut at a position indicated by a one-dot chain line by using a pulse laser, a one-dot chain line is used due to the nature of the pulse laser. The workpiece 20 cannot be divided at the position shown, and in practice, two workpieces 20A and a workpiece 20B as shown in FIG. 5B are produced.

This is because the width of the region to be processed and removed on the laser incident surface side (surface 21 side) and the emission surface side (surface 22 side) in the cutting of the workpiece 20 by a pulse laser (left and right direction in the figure). This is because of changes. In FIG. 5B, the region to be processed and removed is indicated by hatching. Therefore, the angle α and the angle β formed by intersecting each of the surfaces 21 and 22 and the cut surfaces 20a and 20b formed by cutting do not become the desired 90 degrees.

With respect to such a workpiece 20B, the machining surface 20b faces the surface 1a of the tool base material 1 with respect to the tool base material 1 (the angle formed by the surfaces 1a and 1b is 90 °) as shown in FIGS. In the meantime, when both surfaces are arranged so that the surface 22 faces the surface 1b of the tool base material 1, the mutually facing surfaces of the tool base material 1 and the workpiece 20B are not parallel to each other. For this reason, it is necessary to change the thickness of the bonding layer 2 so as to follow the gap without filling the gap between the mutually facing surfaces of the tool base material 1 and the workpiece 20B.

When the thickness of the bonding layer 2 is not uniform, the stress applied to the bonding surface during the bonding process becomes non-uniform, and as a result, the bonding strength between the workpiece 20B and the tool base material 1 may be insufficient. In particular, under the conditions of pulse lasers conventionally used, the actual situation is that the angle α shown in FIG. 5B is 88 ° or less.

On the other hand, according to the pulse laser satisfying the above condition A, the angle α between the manufactured processed surface 20b and the surface 22 intersecting with the processed surface 20b can be set to 89.0 ° to 90.0 °. Similarly, the angle β between the processed surface 20b and the surface 21 intersecting with the processed surface 20b can be set to 90.0 ° to 91.0 °. That is, in the cBN sintered body tool, a cBN sintered body in which an angle formed by two mutually intersecting surfaces to be bonded surfaces is 89.0 to 91.0 ° can be used.

For this reason, it is possible to reduce the gap between the facing surfaces of the tool base material 1 and the workpiece 20B. Therefore, since the thickness of the joining layer 2 can be made uniform as compared with the conventional case, the stress applied to the joining surface during the joining process becomes uniform. As a result, the tool base material 1 and the cBN sintered body 3 The bonding strength can be further increased. Further, from the viewpoint of further increasing the bonding strength, the angle α is more preferably 89.5 ° to 90.0 °, and the angle β is more preferably 90.0 to 90.5 °. That is, in the cBN sintered body tool, a cBN sintered body in which an angle formed by two mutually intersecting surfaces to be bonded surfaces is 89.5 to 90.5 ° is preferable.

[Second Embodiment]
In the first embodiment described above, the cBN sintered body from which the support plate has been removed is laser processed, and this is used as the cBN sintered body tool. However, in this embodiment, the support plate is not removed and the support is removed. Laser processing is performed on the cBN sintered body with the plate, and this is used as a cBN sintered body tool.

Specifically, as shown in FIG. 6, a support plate 4 is attached to one surface of the cBN sintered body 3. That is, in the present embodiment, the support plate 4 is disposed between the cBN sintered body 3 and the bonding layer 2. Since the cBN sintered body 3 and the support plate 4 have undergone the sintering process as described above, they are firmly bonded to each other.

The support plate 4 may be a support plate 42 after the sintering process as shown in FIG. 4B or may be a part of the support plate 42. That is, the support plate 4 may be present on one surface of the cBN sintered body 3 by leaving all of the support plate 42 after the sintering step, or without removing all of the support plate 42. You may make it exist on one surface of the cBN sintered compact 3 by leaving a part.

In the present embodiment, similarly to the first embodiment, an altered portion is present on the joining surface 3a side, and thereby the joining strength between the cBN sintered body 3 and the tool base material 1 is enhanced.

[Third Embodiment]
In the above-described first embodiment, the case where the altered portion 31 is present on the joint surface 3a of the cBN sintered body 3 has been described. However, in the present embodiment, the joint surface 3a and the joint surface 3b of the cBN sintered body 3 are described. A case in which the altered portion 31 exists on both sides of will be described. In addition, since it is the same as that of 1st Embodiment except the quality change part 31 existing in the joint surface 3b, the description is not repeated.

Referring to FIG. 2, the above-described altered portion 31 exists on both the joining surface 3 a and the joining surface 3 b of the cBN sintered body 3. Such a cBN sintered body can be produced not only by forming the joint surface 3a but also by forming the joint surface 3b by performing the above-described processing steps.

According to the cBN sintered body tool 10 of the present embodiment, the presence of the altered portion 31 in each of the joining surface 3a and the joining surface 3b increases the joining strength between the cBN sintered body 3 and the tool base material 1. .

Further, when the bonding surface 3a and the bonding surface 3b are manufactured, each surface is manufactured by a pulse laser that satisfies the processing condition A, so that the angle formed by both surfaces of the bonding surfaces 3a and 3b (that is, the ridge line 3c in FIG. Angle) can be 89.0 ° or more and 91.0 ° or less. For this reason, since the thickness of the joining layer 2 can be made uniform as compared with the conventional case, the stress applied to the joining surface during the joining process becomes uniform, and as a result, the tool base material 1 and the cBN sintered body 3 The joint strength can be further increased.

Hereinafter, the present embodiment will be described in more detail with reference to examples, but the present embodiment is not limited thereto.

[Example 1]
A cBN sintered body tool having the shape shown in FIGS. 1 and 2 was produced as follows.

First, TiN powder and Al powder (each having an average particle size of about 20 μm) were mixed to a mass ratio of 4: 1 to prepare a mixture. Next, the mixture was heat-treated at 1250 ° C. for 30 minutes in a vacuum. The mixture obtained by the heat treatment was pulverized using a φ4 mm cemented carbide ball and a cemented carbide pot to obtain a raw material powder for the binder phase (pulverization step).

Next, cBN powder composed of cBN particles (average particle size is about 4 μm) is prepared, and the mixing ratio (volume%) of the binder phase raw material powder and cBN phase cBN powder is 39:61. Both powders were mixed together to prepare a mixed powder. The mixed powder was placed in a vacuum furnace, heated to 950 ° C., and held for 30 minutes to degas the mixed powder. Then, the mixed powder after degassing is laminated on a support plate made of cemented carbide and filled into a capsule made of Mo, and the capsule is placed in an ultra-high pressure apparatus, and is sintered under the following sintering conditions. (Sintering process). After the sintering step, the sintered body was taken out from the capsule, the support plate was ground and removed, and then the shape was adjusted by grinding to prepare a disk-shaped cBN sintered body.

(Sintering conditions)
Pressure: 5GPa
Temperature: 1300 ° C
Time: 20 minutes.

Next, the disk-shaped cBN sintered body was processed using a fiber laser device under the following processing conditions (processing step). Thereby, as shown in FIGS. 1 and 2, an isosceles triangle having two sides of 2 mm and an apex angle of 80 ° between them is a bottom surface and a thickness of 1.0 mm is cut into a triangular prism-shaped cBN sintered body. It was. Of the cBN sintered body cut out, a rectangular surface is a laser processed surface.

(Laser processing conditions)
Laser oscillator: YLR-150 / 1500 (model number) manufactured by IPG
Amplification medium: Optical fiber Pulse energy: 0.02J
Pulse width: 0.10 msec
Output: 150W
Frequency: 300Hz
Wavelength: 1070 nm
Introduced gas: Nitrogen Processing speed: 50 mm / min. .

Next, a tool base material made of cemented carbide is prepared, and 25% by mass of Ti, 25% by mass of Zr, 30% by mass of Cu, and 20% by mass of cBN sintered body and the tool base material. A material for the bonding layer made of Ni was sandwiched, and this laminate was placed in a vacuum furnace. Then, the pressure inside the vacuum furnace is set to 1 × 10 ⁻² Pa, the internal temperature is raised to 850 ° C., and the material for the bonding layer is melted to join the cBN sintered body and the tool base material. I let you. The cBN sintered body has one processed surface formed by the above-described processing steps, and the processed surface is disposed so as to correspond to the joint surface 3a of the cBN sintered body in FIGS. The processing surface (surface corresponding to the surface 22 in FIG. 5B) was arranged so as to correspond to the bonding surface 3b of the cBN sintered body.

Thereafter, the tool base material bonded with the cBN sintered body was taken out of the vacuum furnace and allowed to cool. Then, the periphery of the joint surface between the cBN sintered body and the joint layer and the outer periphery of the joint surface between the tool base material and the joint layer were polished to smooth the periphery of the joint surface. As described above, a cBN sintered body tool having an ISO model number of CNGA120408 and having a cBN sintered body at the apex angle portion was produced.

Table 1 shows various conditions of the method of manufacturing the cBN sintered body tool in Example 1 and various characteristics of the manufactured cBN sintered body tool.

In Table 1, the cBN content ratio column (% by volume) is shown in the column of the cBN content, and the composition of the compound constituting the binder phase is shown in the column of the binder phase. In the column of cutting method, the method of cutting (processing) the cBN sintered body is shown (“FB” means fiber laser), and in the column of pulse width and energy, the pulse width during processing (msec) ) And pulse energy values (J).

The content ratio of cBN in the cBN sintered body was calculated as follows. First, the cBN sintered body after the processing step (without the joining step) was mirror-polished (though the polishing thickness was limited to less than 50 μm), and the cBN sintered body in an arbitrary region was magnified 2000 times with an electron microscope. When the photo was taken with a black area, a gray area and a white area were observed. With the attached energy dispersive X-ray spectrometer (EDX: Energy Dispersive X-ray spectroscopy), it was confirmed that the black region was cBN, and the gray region and the white region were bonded phases other than cBN. Next, the 2000 × photograph taken above was binarized using image processing software to calculate the total area of the region (black region) occupied by cBN particles in the photograph, The percentage of the ratio of the black region in the cBN sintered body was defined as volume%.

In addition, the content rate of cBN in the cBN sintered body coincided with the mixing ratio of the raw materials (the mixing ratio of the BN particles and the material for the binder). From this, even if a part of cBN constituting the cBN sintered body (particularly a part of cBN located in the surface region) is phase-converted to hBN, the content ratio of hBN to the whole cBN sintered body is It was understood that it was less than 1% by volume.

The composition of the compound constituting the binder phase in the cBN sintered body is to perform X-ray diffraction (XRD) on the cBN sintered body after the processing step (without the joining step). Confirmed by In Examples 2 to 41 and Comparative Examples 1 to 20 below, the method for obtaining the content of cBN in the cBN sintered body and the confirmation of the composition of the compound constituting the binder phase were the same as in Example 1. .

[Examples 2 to 25]
With respect to the cBN sintered body tool of Example 1, the composition of the compound constituting the binder phase was changed as shown in Table 1, and the presence or absence of the support (“Yes”: leaving a part of the support, “−” : Remove all of the support) as shown in Table 1 and change the cBN content (% by volume) as shown in Table 1 to carry out the sintering process, and further the pulse width and A cBN sintered body tool was produced in the same manner as in Example 1 except that the pulse energy was changed as shown in Table 1.

In Examples 2 to 8, the same raw material powder for the binder phase as in Example 1 was used. In Examples 9 to 16, a mixture in which cBN powder and AlN powder were mixed at a mass ratio of 8: 1 was used as a raw material powder. In Examples 17 to 25, the cBN powder and the binder powder (Co powder, WC powder, and Al powder mixed at a mass ratio of 2: 7: 1) are in a mass ratio of 9: 1. The mixture thus prepared was used as a raw material powder. In Examples 2, 10 and 18, the surface corresponding to the surface 21 in FIG. 5B was disposed on the surface 3b.

[Examples 26 to 41]
Commercially available pellet-shaped hBN as a raw material is put into a capsule made of a refractory metal, the capsule is introduced into an ultrahigh pressure apparatus, a sintering process is performed under the following sintering conditions, and a pulse width and A cBN sintered body tool was produced in the same manner as in Example 1 except that the pulse energy was changed as shown in Table 2. In this sintering process, hBN was directly converted to cBN.

(Sintering conditions)
Pressure: 10GPa
Temperature: 2100 ° C
Time: 20 minutes.

Among Examples 1 to 41, in Examples 8, 16, 25, and 38 to 41, a YAG laser was used instead of the fiber laser. Even when the YAG laser was used, the other processing conditions were the same as in Example 1 except that the pulse width and pulse energy were changed as shown in Table 1. However, in the fiber laser, the specifications were a spot diameter and a laser spread angle of 10 μm and 1.0 mm / mrad, respectively, whereas in the YAG laser, the specifications were larger than these values. Among Examples 1 to 41, Examples 2, 10, 18 and 27 are arranged such that the surface corresponding to surface 21 in FIG. 5B is positioned on surface 3b, and otherwise, corresponds to surface 22 in FIG. 5B. It arrange | positions so that the surface to perform may be located in the surface 3b.

[Comparative Examples 1 to 20]
Regarding the pulverization step, in Comparative Examples 1 to 5, the same binder phase raw material powder as in Example 1 was used, and in Comparative Examples 6 to 10, the same binder phase raw material powder as in Example 7 was used. In Comparative Examples 11 to 14, the same raw material powder for the binder phase as in Example 13 was used. The mixing ratio of the cBN powder is as shown in the cBN content (volume%) in Table 3.

Further, regarding the processing steps, the processing shown in Table 3 was performed in Comparative Examples 1 to 20. In Table 3, YAG (thermal) and YAG (non-thermal) mean thermal processing with a YAG laser and non-thermal processing with a YAG laser.

Regarding Table 3, the processing conditions of WEDM, wire saw, thermal processing with YAG laser, and non-thermal processing with YAG laser are as follows.

(WEDM processing conditions)
Wire material: Brass Wire diameter: 0.3mm
Cutting speed: 2 mm / min. .

(Wire saw processing conditions)
Wire material: Diamond Wire diameter: 0.2mm
Cutting speed: 0.05 mm / min. .

(Processing conditions for thermal processing with YAG laser)
Laser processing machine: MS35
Amplification medium: YAG
Pulse energy: 1.6J
Pulse width: 0.5msec
Output: 40W
Frequency: 100Hz
Wavelength: 1064nm
Processing speed: 50 mm / min. .

(Processing conditions for non-thermal processing with YAG laser)
Laser oscillator: Hawk-Pro-532
Amplification medium: YAG
Pulse width: 25nsec (0.025msec)
Output: 15W
Frequency: 1000Hz
Wavelength: 532 nm
Processing speed: 50 mm / min. .

[Thermal conductivity of cBN sintered body]
The thermal conductivity of each of the cBN sintered bodies of Examples 1 to 41 and Comparative Examples 1 to 20 was determined by a laser flash method in accordance with “JIS R1611: 2010”. Specifically, first, a sample for a measurement sample is cut out from the cBN sintered body after the processing step (the bonding step is not performed), and is sufficiently polished until there is no altered portion on the sample surface, and the diameter is 18 mm and the thickness is 1 mm. A measurement sample was prepared. The surface of the measurement sample was irradiated with pulsed laser light, the specific heat and the thermal diffusivity were measured, and the thermal conductivity was calculated using these. The results are shown in Tables 1 to 3. The laser beam had a wavelength of 1.06 μm and a pulse width of 0.4 ms.

[Evaluation 1: Presence or absence of altered part]
In each cBN sintered compact tool, it was observed by Raman spectroscopic analysis and EDS analysis whether or not an altered portion is present on the surface of the cBN sintered compact that contacts the bonding layer.

Regarding the Raman spectroscopic analysis, first, a surface corresponding to the surface shown on the paper surface of FIG. 2 of the cBN sintered body tool was subjected to CP processing using a CP apparatus to prepare a sample for observation. Next, this CP processed surface was observed using a Raman spectroscope (HORIBA LabRAM HR-800, wavelength: 532 nm), and hBN, B ₂ O ₃ in the vicinity of the contact surface in contact with the bonding layer in the cBN sintered body, And the presence or absence of B ₂ ON ₃ was observed.

Regarding EDS analysis, the CP processed surface was observed using an EDS analyzer (JED-2300, manufactured by JEOL Ltd.), and the presence or absence of B in the vicinity of the contact surface in contact with the bonding layer in the cBN sintered body was observed.

In a sample in which at least one component of hBN, B, B ₂ O ₃ , and B ₂ ON ₃ is observed, a region in which any of the above components exists from the position of the contact surface in contact with the bonding layer Among these, the shortest distance to the innermost position was defined as the thickness (μm) of the altered portion. The results are shown in Tables 1 to 3.

As shown in Tables 1 to 3, in a cBN sintered body processed by a fiber laser and a cBN sintered body processed by thermal processing using a YAG laser, an altered portion exists on the surface corresponding to the surface 3a. Was confirmed. In addition, the confirmed altered part was formed in the whole surface of each surface in any cBN sintered compact.

For Comparative Examples 14 and 20, the cBN sintered body could not be processed by WEDM.

[Evaluation 2: Angle formed by joint surface of cBN sintered body]
The above polished surface was observed using a microscope, and the angle formed by the bonded surfaces (the angle formed by the surfaces 3a and 3b) was measured. The results are shown in Tables 1 and 2.

[Evaluation 3: Bonding strength]
In each cBN sintered body tool, the bonding strength between the cBN sintered body and the tool base material was measured. A method for measuring the bonding strength will be described with reference to FIGS. 7A and 7B.

FIG. 7A is a plan view schematically showing an outline of how to apply the punching bar when measuring the bonding strength of the cBN sintered body tool, and FIG. 7B measures the bonding strength of the cBN sintered body tool. It is the front view which showed typically the outline of how to apply the punching rod at the time.

As shown in FIG. 7A and FIG. 7B, a punching rod made of cemented carbide is used so that only the cBN sintered body 3 of the cBN sintered body tool 10 is loaded and the tool base material 1 is not loaded. 30 was brought into surface contact with the side surface of the cBN sintered body 3. In addition, when the cBN sintered compact tool 10 had the support plate 4, it adjusted so that a load might be applied to both the cBN sintered compact 3 and the support plate 4. FIG. And after fixing so that the tool base material 1 might not move, the load of the punching rod 30 was increased gradually, and the load when the cBN sintered compact 3 fractured | ruptured from the tool base material 1 was measured. The load at the time of fracture was divided by the bonding area between the cBN sintered body 3 and the tool base material 1 to calculate the bonding strength (kgf / mm ² ) per unit area. The results are shown in Tables 1 to 3.

As shown in Tables 1 to 3, the cBN sintered body tool of the example has higher bonding strength between the cBN sintered body and the tool base material than the cBN sintered body tool of the comparative example. confirmed.

It should be considered that the embodiments and examples disclosed this time are examples in all respects and are not restrictive. The scope of the present invention is shown not by the above-described embodiments and examples but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.

1 tool base material, 2 bonding layer, 3,3A cBN sintered body, 4 support plate, 10 cBN sintered body tool, 31 altered part, 32 substrate, 1a, 1b, 3a, 3b surface, 3c ridge line, 20 workpiece Workpiece, 20A, 20B workpiece, 20Bb machined surface, 20a entrance surface, 20b exit surface, 30 punched bar.

Claims (9)

1. Tool base material,
   A bonding layer provided on a surface of the tool base material;
   A cubic boron nitride sintered body joined to the tool base material via the joining layer,
   The cubic boron nitride sintered body has a bonding surface to be bonded to the bonding layer,
   On the at least one surface side of the joint surface, there is an altered portion containing at least one selected from the group consisting of hexagonal boron nitride, boron, boron oxide, and boron oxynitride,
   The altered boron part is a cubic boron nitride sintered body tool having a thickness of 0.1 μm or more and 50.0 μm or less.
2. The cubic boron nitride sintered body tool according to claim 1, wherein the altered portion has a thickness of 0.3 µm or more and 5.0 µm or less.
3. The cubic boron nitride sintered body tool according to claim 1 or 2, wherein the cubic boron nitride sintered body has a cubic boron nitride content of 80.0 vol% or more.
4. The cubic boron nitride sintered body tool according to claim 1 or 2, wherein a content ratio of cubic boron nitride in the cubic boron nitride sintered body is 96.0% by volume or more.
5. 5. The cubic boron nitride according to claim 1, wherein an angle formed by two of the joint surfaces intersecting each other is 89.0 ° or more and 91.0 ° or less. Sintered body tool.
6. The cubic boron nitride sintered body tool according to any one of claims 1 to 5, wherein the cubic boron nitride sintered body has a thermal conductivity of 70 W / m · K or more.
7. A cubic boron nitride sintered body used for the cubic boron nitride sintered body tool according to any one of claims 1 to 6.
8. Cubic boron nitride sintered comprising a tool base material, a joining layer provided on the surface of the tool base material, and a cubic boron nitride sintered body joined to the tool base material via the joining layer. A method of manufacturing a body tool,
   A step of sintering the boron nitride particles to produce a vertical s tetragonal boron nitride sintered body;
   Laser processing the cubic boron nitride sintered body with a pulse laser;
   Bonding the laser-processed cubic boron nitride sintered body to the tool base material via the bonding layer, and
   In the step of processing, the pulse energy in the pulse laser is 0.01 J or more and 1.5 J or less, the pulse width is 0.01 msec or more and 0.40 msec or less, and the output is 30 W or more and 500 W or less. Method for manufacturing a boron sintered body tool.
9. The method for manufacturing a cubic boron nitride sintered body tool according to claim 8, wherein the pulse laser is a fiber laser.

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