JP2008290130A - Zygote - Google Patents

Abstract

The present invention provides a cutting tool suitable for high-speed cutting, CVD coating processing, etc., in which the bonding strength of the bonding layer does not decrease even when the temperature of the brazing material becomes higher than the temperature at which the liquid phase is generated during cutting. A simple assembly.
A plurality of materials to be joined made of different materials are joined by a joining layer that does not generate a liquid phase at less than 1000 ° C. In this case, the plurality of materials to be joined are joined by energization and pressure joining using the joining material 2 accompanied by deformation while preferentially generating heat over the materials to be joined by energization and pressurization. Furthermore, it is preferable that the bonding material has a space inside and has a larger electric resistance than at least one of the plurality of bonded materials.
[Selection] Figure 1

Description

  The present invention relates to a joined body, and more particularly to a joined body suitable for a cutting tool.

  Conventionally, as represented by cBN (cubic boron nitride) or diamond cutting tools, cutting tools with high-hardness materials joined to the tip by brazing have been manufactured and used for special steel materials and other various cutting processes. ing.

Specifically, for example, tools in which cBN and cemented carbide are joined by brazing are manufactured and sold (for example, Non-Patent Document 1). Alternatively, a joined body in which PCD (sintered diamond) or cBN and ceramics or cermet are joined by brazing has been proposed (for example, Patent Document 1 and Patent Document 2). A cutting tool in which a cemented carbide or cermet and high-speed steel or the like are joined by brazing using a Cu brazing material has also been proposed (for example, Patent Document 3).
Published by Sumitomo Electric Hardmetal Co., Ltd., Igetaroy cutting tools ('07 -'08 general catalog), October 2006, p. L4, Coated Sumiboron Series JP 2002-360008 A Japanese Patent No. 3549424 Japanese Patent Laid-Open No. 11-294058

  However, in many of the brazing materials, a liquid phase appears at about 700 to 800 ° C. For this reason, it has been difficult to use a cutting tool using a joined body by brazing for high-speed cutting or the like that may exceed the aforementioned temperature during cutting. Moreover, the liquid phase produced | generated at the time of brazing oozes and soils a to-be-joined material, and had a bad influence at the time of the process which is a post process.

  In order to improve the wear resistance of the joined body, a coating treatment may be applied, but a coating that requires a high temperature exceeding the above-described temperature (for example, a CVD coating requires 1000 ° C. or higher). ) Processing was also difficult.

  In view of the above problems, the present invention provides high-speed cutting, CVD coating processing, or the like that does not reduce the bonding strength of the bonding layer even when the temperature exceeds the temperature at which the brazing material generates a liquid phase during cutting. It is an object of the present invention to provide a joined body suitable as a cutting tool suitable for the above.

As a result of intensive studies, the present inventor has found that the above-described problems can be solved by the inventions of the claims described below.
The invention of each claim will be described below.

The invention described in claim 1
A joined body in which a plurality of materials to be joined made of different materials are joined by a joining layer that does not generate a liquid phase at a temperature lower than 1000 ° C.

  In invention of Claim 1, since it joined by the joining layer which does not produce | generate a liquid phase at less than 1000 degreeC, when this joined body is used as a cutting tool and cutting operation is performed, 800 degreeC will be carried out during operation | work. Even if the temperature is higher, the bonding layer does not generate a liquid phase, and the bonding strength does not decrease. Therefore, it is possible to provide a cutting tool suitable for high-speed cutting at 1000 ° C. or higher. The “different materials” in the first aspect of the invention include materials different from each other in addition to materials of the same type and different only in composition.

  Moreover, it becomes possible to give a CVD coating etc. to a conjugate | zygote. As a result, for example, it is possible to perform CVD coating on cBN tools that could not be applied in the past, and it is possible to further extend the service life and handle various types of materials to be cut. In this case, the bonding layer is preferably a bonding layer that does not generate a liquid phase at a temperature lower than 1100 ° C., which is slightly higher than the temperature of the CVD coating. This is because the influence on the deformation of the bonding layer due to a rapid temperature change or the like during the CVD coating, and the decrease in the bonding strength can be reduced.

The invention described in claim 2
2. The heat generation is preferentially generated by energization and pressurization over the materials to be bonded, and the plurality of materials to be bonded are bonded by energization and pressure bonding using a bonding material with deformation. It is a conjugate | zygote as described in.

In the invention of claim 2, after inserting a joining material (hereinafter also referred to as “insert material” to distinguish it from “conventional brazing material”) between a plurality of materials to be joined, it is put in a heating furnace or the like. Rather than being heated and joined at a temperature at which a liquid phase is generated in the joining material, the joining material is densely joined by energization and pressure joining in which energization joining is performed while positively pressing. In this case, since an insert material that generates heat preferentially over the material to be joined by energization and pressurization is used, the insert material is heated to a higher temperature than the material to be joined, without heating the material to be joined at a high temperature, Only the vicinity of the insert material can be effectively heated at a high temperature. For this reason, deformation (for example, partial melting) of the materials to be joined and particle coarsening are not caused.
In addition, since insert materials that are deformed by energization and pressurization are used, the movement of the substance accompanying the deformation of the insert materials effectively acts on the bonding of the interface between the material to be joined and the insert material, and the bonding strength is high. You can get a body.

The invention described in claim 3
The joined body according to claim 2, wherein the joining material has a space inside.

  In invention of Claim 3, since the insert material which has space inside is used as an insert material, the deformation | transformation by the said heating is performed easily and a joined body with high joint strength can be obtained easily. . Here, the insert material having a space inside includes a material in which the space appears in the same form on the surface. Specific examples of such an insert material include powder and porous (for example, net-like or fiber-like) sheets. The particle size of the powder and the porous state are appropriately selected as necessary.

The invention according to claim 4
4. The joined body according to claim 2, wherein the joining material has a larger electric resistance than at least one of the plurality of materials to be joined. 5.

  In the invention of claim 4, since an insert material having an electric resistance (including electrical contact resistance) larger than at least one of the plurality of materials to be joined is used as the insert material, Furthermore, heat can be preferentially generated over the material to be joined.

As a specific method of energization and pressure bonding, for example, first, a porous insert material having an electric resistance larger than the electric resistance of the material to be bonded is sandwiched between the materials to be bonded, and each material to be bonded includes graphite or the like. An electrode made of a conductive material is disposed. When a current is passed through the electrode while applying pressure, the insert material quickly generates resistance heat, and the vicinity of the insert material can be heated to a higher temperature than the material to be joined, and the material to be joined can be joined in a short time. A joined body with high joining strength can be obtained by deformation of the insert material. The joining time is preferably within 30 seconds, and more preferably within 10 seconds.
Even when an insert material having a large electric resistance is used, the electric resistance of the insert material after bonding may be smaller than the electric resistance of the material to be bonded.
Moreover, although the electrical resistance of insert material and the electrical contact resistance with a to-be-joined material should just be larger than the electrical resistance of any one of a to-be-joined material, it is more preferable that it is larger than any to-be-joined material.

The invention described in claim 5
The joined body according to any one of claims 1 to 4, wherein the joined body is a cutting tool.

  In the invention of claim 5, since the liquid phase is not generated when the bonding layer is less than 1000 ° C., the bonding strength of the bonding layer does not decrease even in high-speed cutting where the brazing material has a temperature higher than the liquid phase. A cutting tool can be provided.

The invention described in claim 6
6. The joined body according to claim 1, wherein the joining layer is made of a metal, an alloy, or a material containing a ceramic or an intermetallic compound therein.

  In the invention of claim 6, since a bonding layer containing a metal or an alloy that does not generate a liquid phase at a temperature lower than 1000 ° C. or a ceramic or an intermetallic compound therein is formed, the bonding strength is stably high. A joined body can be provided.

  In the above, ceramics or intermetallic compounds may be contained in the insert material from the beginning. Moreover, the element which comprises ceramics or an intermetallic compound is contained in another state in the insert material, and it may be produced | generated by the reaction after completion of joining. When such a ceramic or intermetallic compound is produced by reaction, reaction heat can be used for joining, which is more effective for joining.

The invention described in claim 7
The joined body according to claim 6, wherein the joining layer is formed using a material in a non-equilibrium state.

  In the invention of claim 7, since a material in a non-equilibrium state (for example, amorphous, nanocrystal or supersaturated solid solution) is used as an insert material, reaction heat can be used for joining. And after joining is complete | finished, the joining layer which does not produce | generate a liquid phase to high temperature can be obtained.

  Specifically, when the material in the non-equilibrium state is heated, it releases excessive heat (energy that has maintained the non-equilibrium state), that is, is stabilized with an exothermic reaction. . After stabilization, if the constituent element of the material is a metal element, it becomes a material that does not generate a liquid phase up to a high temperature, such as an intermetallic compound, and if the metal element and carbon are carbides.

  As a method for producing an insert material in a non-equilibrium state, there are a mechanical alloying method (mechanical alloying method), a rapid quenching method, and the like. In particular, the mechanical alloying method is preferable because a material that does not generate a liquid phase up to a high temperature can be unbalanced without generating a liquid phase.

The invention according to claim 8 provides:
The joined body according to claim 6, wherein the ceramic contains an oxide, a carbide, a nitride, a carbonitride, a silicide, or a boride.

In the invention of claim 8, more preferable ceramics are specified as the ceramics of claim 6. Specific examples include Al ₂ O ₃ , TiO ₂ , TiC, TiN, TiSiCN, TiB ₂ , ZnN, WC, WSi ₂ , MoSi _{2 and the} like.

The invention according to claim 9 is:
The joined body according to any one of claims 1 to 8, wherein the joining layer contains at least one element constituting the material to be joined.

  In the invention of claim 9, since the joining layer contains at least one element constituting the material to be joined, joining with the material to be joined is performed more efficiently, and a joined body with higher joining strength. Can be obtained. In particular, it is more preferable that the binder phase component of the metal or alloy constituting the joining layer contains at least one binder phase component constituting the material to be joined.

  For example, when at least one of the materials to be joined is a cemented carbide, it is preferable to use an insert material containing ceramics such as Co and WC. Alternatively, when one of the materials to be joined is cermet, it is preferable to use an insert material containing Ni and TiC. These ceramics may be contained in the insert material in another state. For example, when a mixture of Co, W, and C by a ball mill is used as an insert material, they react after bonding, and the bonding layer is made of Co and WC.

The invention according to claim 10 is:
The bonding layer is made of titanium (Ti), cobalt (Co), nickel (Ni), iron (Fe), or an alloy containing at least one of the metals. Item 10 is a joined body according to any one of Items 9.

  In the invention of claim 10, it is generally used as a binder phase component of the material to be joined, and includes at least one of Ti, Co, Ni, and Fe having a liquid phase generation temperature of 1400 ° C. or higher. A bonded body with higher bonding strength can be obtained.

For example, when cemented carbide and cermet are joined, it is preferable that Co or Ni used as a binder phase component of each material to be joined, or an alloy thereof.
Moreover, when joining cBN and a cemented carbide, it is preferable to use the material containing Ti contained in the binder phase of cBN as an insert material. In this case, it is preferable to use a material that forms an intermetallic compound by bonding with Ti, because the temperature at which the bonding layer generates a liquid phase can be further increased and the strength can be increased.

The invention according to claim 11
11. The joined body according to claim 1, wherein the material to be joined is cemented carbide, cermet, cBN, diamond, or steel.

In the invention of claim 11, since a hard material such as cemented carbide, cermet, cBN, diamond, steel or the like is used as the material to be joined, any one of these and the other kind are interposed via the joining layer. The joined body obtained by joining together can be suitably used as a cutting tool.
As the steel, carbon tool steel, alloy tool steel, die steel, and high speed tool steel are preferably used.

The invention according to claim 12
One of the said to-be-joined materials is cBN, The joined body of Claim 11 characterized by the above-mentioned.

  Since cBN is vulnerable to heat and easily decomposed at high temperatures, it is susceptible to thermal degradation in a short time. For this reason, conventionally, it was difficult to obtain a joined body joined by a joining layer that does not generate a liquid phase even at a high temperature due to thermal effects during brazing.

  However, since the joined body according to the invention of Claim 12 is joined within a short time, specifically, for example, within 30 seconds, further within 10 seconds, by energization and pressure joining, the material to be joined is cBN. However, it is possible to provide a tool that can fully utilize the characteristics such as the high hardness of the cBN tool without causing decomposition, thermal deterioration, or reduction in the bonding strength of the bonding layer.

  Note that cBN can form a bonding layer without necessarily requiring a back metal (a thin plate provided on the opposite side of the cutting surface). In this case, it is preferable to use, as an insert material, a material that forms an intermetallic compound by bonding with Ti, which is a binding phase of cBN, because the temperature at which the bonding layer generates a liquid phase can be further increased and the strength can be increased.

The invention according to claim 13
One of the said to-be-joined materials is a cermet, The joined body of Claim 11 characterized by the above-mentioned.

  In the invention of claim 13, since the cermet having excellent heat resistance and oxidation resistance is used for the material to be joined as compared with the cemented carbide containing WC as a main component, the present invention is more effectively applied. Can do.

The invention according to claim 14
The joined body according to claim 13, wherein 80 vol% or more of the bonded phase of the cermet is Co.

In the invention of claim 14, since 80 vol% or more is replaced with Co instead of Ni normally used for the binder phase of cermet, the thermal crack resistance is improved, and resistance to rapid heating and rapid cooling during energization and pressure bonding. Can be increased. In addition, for example, when CVD coating (film quality: TiCN + Al ₂ O ₃ , thickness: 2 μm each) is performed at 1000 ° C., Ni adversely affects the formation of the CVD film, but the bonding phase is 80 vol% or more. By using Co, a good CVD film can be formed.

  As a cutting tool suitable for high-speed cutting, CVD coating processing, etc., the bonding strength of the bonding layer does not decrease even when the temperature of the brazing material exceeds the temperature at which the liquid phase is generated during cutting. A suitable joined body can be provided.

  The best mode for carrying out the present invention will be described below based on the following examples. Note that the present invention is not limited to the following embodiments. Various modifications can be made to the following embodiments within the same and equivalent scope as the present invention.

First, an outline of joining by energization and pressure joining will be described with reference to the drawings.
FIG. 1 is a conceptual diagram illustrating joining of a cemented carbide to a cermet base by energization and pressure joining. In FIG. 1, materials 1 and 3 to be joined are cermet and cemented carbide, respectively, and are joined using an inserted insert material 2. Specifically, the materials to be bonded 1 and 3 and the insert material 2 are sandwiched between electrodes (graphite) 4 and pressed, and a current is passed through the electrode 4 in the direction indicated by the arrow 5.
As the insert material 2, the insert material shown in claim 2 that generates heat preferentially over the material to be joined by energization and pressurization and is accompanied by deformation is used. At this time, an insert material having a space in the interior shown in claim 3 or an insert material having an electric resistance larger than at least one of the plurality of materials to be joined shown in claim 4 is preferable.
As a result, the insert material 2 generates resistance heat in a concentrated manner (preferentially), the vicinity of the insert material 2 is centrally heated, and the materials 1 and 3 to be joined are joined. In addition, when a carbon sheet is arrange | positioned between each of the two electrodes 4 and the to-be-joined materials 1 and 3, the surface roughness of each member can be absorbed and it is preferable.

  The energization conditions are appropriately determined depending on the material to be joined and the material of the insert material, etc., but in order not to cause deformation / melting of the material to be joined and coarsening of the particles other than in the vicinity of the insert material. Within about 30 seconds is preferable.

  As a form of the insert material for performing energization and pressure bonding, it is preferable that the electric resistance is high in the initial state and the form is easy to concentrate heat. As a specific form, a powder or porous (for example, net-like or fiber-like) sheet is preferable. Etc. The particle size of the powder and the porous state are appropriately selected as necessary.

As described above, when the insert material has a high electric resistance in the initial state and is in a form that tends to concentrate heat, the insert material is heated more intensively in the initial stage of energization, and then the powder is sintered or the porous sheet is formed. By being deformed, the heat becomes uniform, and the joining between the insert material and the material to be joined proceeds more easily.
According to this method, it is not necessary to completely melt the entire insert material unlike the conventional brazing material, and the insert material is joined to the material to be joined as the powder is sintered and the porous sheet is deformed. In this case, it is presumed that the insert material is atomically diffused in the material to be joined in the micro area of the joining surface and the joining is proceeding.

A plate-like cemented carbide (90 wt% WC-10 wt% Co) with a side of about 5 mm and a thickness of about 1 mm, and a plate-like cermet with a side of about 25 mm and a thickness of about 5 mm (45 wt% TiCN-30 wt%) _{WC-10wt% Mo 2 C-} 15wt% Ni) and was used as a material to be joined, the insert material, using Ni powder (Co. Kojundo Chemical Laboratory). At that time, the amount of Ni powder was adjusted so that the final thickness of the bonding layer was 20 μm.

  The joining was performed using an apparatus (Plasman manufactured by S.S.Alloy Co., Ltd.) capable of applying a pulse current in a vacuum. As an electrode, graphite was used, and the pulse conditions were a vacuum degree of 10 Pa, a peak pulse current of 1200 A, a pulse frequency of 100 Hz, an energization time of 6 sec, and a load of 1.96 kN.

  In the obtained bonded body, the cemented carbide and the cermet were bonded, and a state where Ni powder was densely sintered in the bonding layer could be observed. The joint strength (shear fracture strength) of this joined body was about 180 MPa, and it was confirmed that the joint body had sufficient joint strength.

Next, an example using a porous sheet as an insert material is shown.
The same cemented carbide and cermet as in Example 1 were used as the materials to be joined, and two cemented carbides were used, and the insert material was nickel mesh (wire diameter 0.1 mm, mesh opening 0.5 mm). Then, a pulse current was applied, and two cemented carbides were joined to one cermet. The pulse conditions were a pulse current of 2000 A, a frequency of 100 Hz, an energization time of 5 sec, and a load of 1.96 kN.
In the obtained joined body, the cemented carbide and the cermet were joined, and the joining strength was about 200 MPa, and it was confirmed that the joining body has a sufficient joining strength.

Next, cBN with a thin plate (back metal) of a thin cemented carbide (92 wt% WC-8 wt% Co) and a cemented carbide (94 wt% WC-6 wt% Co) were joined to the opposite side of the cutting surface. An example is shown.
As an insert material, Co powder (manufactured by Kojundo Chemical Laboratory Co., Ltd.) was used. In order to make it close to the product shape, counterbore was put on the cemented carbide side and cBN was fitted, and then the cemented carbide in the vicinity of cBN was heated by partially concentrated energization together with cBN. In addition, the apparatus which can evacuate at high speed and can complete joining in a short time was used for joining. The pulse conditions were a pulse current of 2000 A and a load of 0.98 kN.

As a result, a bonded body of cemented carbide and cBN having a bonding layer thickness of about 10 μm could be obtained. Note that the energization time at this time was 6 seconds, and the bonding was completed after setting the sample, and was completed in 30 seconds until the sample was taken out.
Moreover, even if it used the mixed powder of Co and WC as an insert material, joining was possible. When the amount of Co in the insert material was set to 20 wt% or more, a greater good bonding strength was obtained.

Next, an example using an insert material prepared using a mechanical alloying method is shown.
In the same manner as in Example 3, joining of cBN and cemented carbide (94 wt% WC-6 wt% Co) was performed. However, the cBN used was different from that used in Example 3 and had no cemented carbide thin plate (back metal) attached.

First, after each powder of Ti, Fe, and Si (silicon) was weighed so as to be Ti-6 wt% Si-2 wt% Fe, it was mixed by a mechanical alloying method to form an amorphous powder. This amorphized powder is in a non-equilibrium state, and a large exothermic reaction appears at about 500 ° C. and stabilizes. After stabilization, a mixture of Ti and Ti ₅ Si ₃ intermetallic compound is formed. This mixture does not produce a liquid phase up to about 1300 ° C.

  Using the obtained amorphous Ti alloy powder as an insert material, as in Example 3, cBN is set in a cemented carbide containing counterbore, and the cemented carbide near the cBN is heated by pulse current to insert the insert material. Heated to join cBN and cemented carbide.

  The bonding strength of the obtained bonded body was determined when the Co powder shown in Example 3 was used as an insert material or when Ti (pure Ti powder contained in cBN binder phase (high purity chemical research)). It was higher than the bonding strength in the case of using (manufactured), and a more preferable bonded body could be obtained.

Next, four types of cermet A (55 wt% TiCN-20 wt% WC-5 wt% Mo ₂ C-5 wt% TaC-15 wt% Ni), B (55 wt% TiCN-20 wt% WC-5 wt% Mo ₂ C-5 wt% _{TaC-8wt% Co-7wt%} Ni), C (55wt% TiCN-20wt% WC-5wt% Mo 2 C-5wt% TaC-13wt% Co-2wt% Ni), D (55wt% TiCN-20wt% WC- An example in which 5 wt% Mo ₂ C-5 wt% TaC-15 wt% Co) and cBN (with back metal) similar to Example 3 are joined is shown. In cermets B, C, and D, the proportions of Co in the binder phase are 53 vol%, 87 vol%, and 100 vol%, respectively.
As an insert material, a cobalt mesh (wire diameter 0.05 mm, mesh opening 0.08 mm) was used.
In each cermet, a counterbore was put in the same manner as in the cemented carbide of Example 3 and cBN was fitted, and then the cemented carbide near the cBN was heated by partially concentrated current.

  As a result, a joined body of cermets A, B, C, D and cBN having a joining layer thickness of about 30 μm could be obtained. When the appearance of the joined body was observed, some cracks were observed in the cermets A and B, but no cracks were generated in the cermets C and D, and it was confirmed that they were very good joined bodies.

  Furthermore, these joined bodies were ground into the shape of ISO standard SNGN120408, and CVD coating was performed by a known method under the conditions of a coating temperature of 1000 ° C. with 3 μm of TiCN and 2 μm of alumina. Although none of the bonded bodies melted the bonding layer, SUJ2 (HRC hardness 60) was subjected to a turning test (cutting conditions: cutting speed 300 mm / min, feed rate 0.15 mm / rev, incision 0.15 mm, dry type 10 min). As a result, the wear amounts of the joined bodies using cermets A, B, C, and D were 0.82 mm, 0.79 mm, 0.23 mm, and 0.19 mm, respectively, and joining using cermets C and D was performed. It was confirmed that the body showed superior wear resistance.

It is a key map explaining energization pressurization joining.

Explanation of symbols

1, 3 Joined material 2 Insert material 4 Electrode 5 Current flow

Claims (14)

  A joined body characterized in that a plurality of materials to be joined made of different materials are joined together by a joining layer that does not generate a liquid phase at less than 1000 ° C.   2. The heat generation is preferentially generated by energization and pressurization over the materials to be bonded, and the plurality of materials to be bonded are bonded by energization and pressure bonding using a bonding material with deformation. The joined body according to 1.   The joined body according to claim 2, wherein the joining material has a space inside.   The joined body according to claim 2 or 3, wherein the joining material has a larger electric resistance than at least one of the plurality of materials to be joined.   The joined body according to any one of claims 1 to 4, wherein the joined body is a cutting tool.   The joined body according to any one of claims 1 to 5, wherein the joining layer is made of a metal, an alloy, or a material containing a ceramic or an intermetallic compound therein.   The joined body according to claim 6, wherein the joining layer is formed using a material in a non-equilibrium state.   The joined body according to claim 6, wherein the ceramic contains an oxide, a carbide, a nitride, a carbonitride, a silicide, or a boride.   The joined body according to any one of claims 1 to 8, wherein the joining layer contains at least one element constituting the material to be joined.   The bonding layer is made of titanium (Ti), cobalt (Co), nickel (Ni), iron (Fe), or an alloy containing at least one of the metals. Item 10. The joined body according to any one of Items 9.   The joined body according to any one of claims 1 to 10, wherein the material to be joined is cemented carbide, cermet, cBN, diamond, or steel.   The joined body according to claim 11, wherein one of the materials to be joined is cBN.   One of the said to-be-joined materials is a cermet, The joined body of Claim 11 characterized by the above-mentioned.   The joined body according to claim 13, wherein 80 vol% or more of the bonded phase of the cermet is Co.

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