JP2016140920A - Composite member, and cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the bond strength of a WC-based hard metal and a composite member made of a WC-based hard metal.SOLUTION: A composite member is prepared by jointing a WC-based hard metal member and a WC-based hard metal member with a bond member made of a Zn foil containing preferably Zn in 98 atom%. The binder phase of the WC-based hard metal in a junction is a composite member containing Zn: 40 to 85 atom% and Co: 15 to 60 atom%, and a tool is made of the composite member.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a composite member and a cutting tool having excellent joint strength at a joint portion, and more particularly, to a composite member obtained by joining a WC-based cemented carbide and a WC-based cemented carbide, and further to a cutting tool comprising the composite member. .

  Conventionally, WC-based cemented carbide, TiCN-based cermet, cBN sintered body, and the like are well known as tool materials. However, in recent years, tool materials are not formed from a single material but as a composite member. Has been proposed to form.

  For example, in Patent Document 1, a cutting edge process is applied to a composite material of a cemented carbide member and a steel member obtained by joining a cemented carbide member and a steel member via a joining layer, or a cemented carbide member of the composite material. In a cutting tool such as an end mill or a drill, the bonding layer on the side in contact with the cemented carbide member is made of Ni, while the bonding layer on the side in contact with the steel member is made of a Ni—Cu alloy, and further, the steel member and the bonding layer It has been proposed to improve the bonding strength between the cemented carbide member and the steel member by forming a Cu diffusion region in which the Cu content decreases as the distance from the bonding surface increases. .

  Further, in Patent Document 2, a blade portion made of cemented carbide and a base portion made of carbon tool steel are joined via a nickel foil or a cobalt foil, and the joint portion is irradiated with a laser, the blade portion and the base portion, It has been proposed to obtain a cutting blade having a small residual stress and a high bonding strength by bonding the two through an alloy layer.

The above-mentioned Patent Documents 1 and 2 propose cutting tools made of a composite member in which different kinds of materials are joined together, but the demand for composite members in which WC-based cemented carbides are joined together is also increasing.
Such a composite member includes, for example, a cutting edge portion made of a composite sintered body in which a WC-based cemented carbide base is joined simultaneously with sintering of a cBN sintered body during ultra-high pressure and high-temperature sintering, and a WC-based cemented carbide tool. Used in the field of cBN cutting tools joined to the main body, and the PDC cutting edge material in which the polycrystalline diamond layer and the WC-based cemented carbide have an integrated laminated structure is connected to the WC-based cemented carbide through the joined portion. It is also used in the technical field of PDC bits used for geothermal well drilling, rock drilling, etc. joined to the tool body.

  For example, in Patent Document 3, in a cutting tool in which a cBN sintered body is bonded onto a WC-based cemented carbide tool base through a bonding portion, one or two of 15 to 65 wt% Ti or Zr is used. There has been proposed a technique for strongly joining a WC-based cemented carbide tool substrate without forming cracks or cracks in the cBN sintered body by forming a joint made of Cu.

  Furthermore, in Patent Document 4, a cBN-based sintered body is bonded onto a WC-based cemented carbide tool base via a joint, and a thickness of 10 to 300 nm is formed at the interface between the cBN-based sintered body and the bonding material. A titanium nitride compound layer is formed, and the thickness of the bonding portion on the back surface of the cBN-based sintered body is made thinner than the thickness of the bonding portion on the bottom surface. It has been proposed to increase the bonding strength.

JP 2009-131971 A JP 2008-100348 A JP-A-11-320218 JP 2012-111187 A

The composite material proposed in Patent Document 1 or a cutting tool made of the composite material exhibits a certain level of performance in cutting under normal conditions, but has sufficient bonding strength under heavy cutting conditions in which a high load acts on the cutting blade. However, there was a risk of damage from the joint.
The cutting blade proposed in Patent Document 2 is a tool for cutting glass fibers into a certain length, and cannot be used as a cutting tool for steel, cast iron or the like.
The cutting tool proposed in Patent Document 3 says that a strong bonding strength can be obtained by using a Ti-based metal. However, if Ti diffuses too much, a tool base made of a cemented carbide shank and a cemented carbide on the cutting edge side. There was a problem that the mechanical properties of the resin deteriorated, causing breakage.
The bonded body having a 10-300 nm titanium nitride compound layer proposed in Patent Document 4 has a problem that the reaction between the bonding material and the cBN-based sintered body is not appropriate, and sufficient bonding strength cannot be obtained. .

Therefore, the present inventors, in order to solve the problems of the conventional composite member and the cutting tool composed thereof, a composite member composed of a WC-based cemented carbide and a WC-based cemented carbide and a cutting tool composed of the composite material, For example, a cutting edge portion made of a composite sintered body in which a WC-based cemented carbide (lining material) is joined simultaneously with sintering of a cBN sintered body during ultra-high pressure and high-temperature sintering, and a WC-based cemented carbide tool base (base metal) As a result of diligent research on measures to improve the joint strength of the joint,
In forming a composite member by joining a WC-based cemented carbide and a WC-based cemented carbide through a joining member made of a Zn single layer foil, Zn: 40 to It has been found that by forming a binder phase having an average component composition of 85 atomic% and Co: 15 to 60 atomic%, the joint strength of the joint part between the WC-based cemented carbides is improved.

  And since the joint strength of the WC base cemented carbide and the WC base cemented carbide having the binder phase having the above average component composition at the joint portion between the WC base cemented carbide alloys improves the joint strength of the joint portion. The cutting tool made from the composite member can prevent the occurrence of breakage from the joint even when subjected to heavy cutting of steel or cast iron where a high load acts on the cutting edge. It has been found that excellent cutting performance can be exhibited.

The present invention has been made based on the above findings,
“(1) A composite member in which a WC-based cemented carbide member and a WC-based cemented carbide member are joined at a joint,
The joint has a thickness of 2 to 50 μm, and the binder phase of the WC-based cemented carbide in the joint has an average composition of Zn: 40 to 85 atomic% and Co: 15 to 60 atomic%. A composite member characterized by comprising:
(2) The composite member is formed by pressure bonding through a bonding member between a WC-based cemented carbide member and a WC-based cemented carbide member, and the bonding member contains 98 atoms of Zn. The composite member according to (1), which is a Zn foil containing at least%.
(3) A tool comprising the composite member according to (1) or (2). "
It is characterized by.

  The present invention is described in detail below.

  As shown in FIG. 1, in the composite member of the present invention, a joining member is disposed between WC-based cemented carbide members (see FIG. 1 (a)), and the WC-based cemented carbide member and the WC-based member are interposed via the joining members. The WC-base cemented carbide member and the joining member are subjected to liquid phase diffusion bonding over a predetermined temperature and time in a state where the cemented carbide member is abutted and a predetermined pressure is applied (see FIG. 1B). Thus, the WC-based cemented carbide member can be formed by joining together (see FIG. 1C).

The liquid phase diffusion bonding employed in the present invention is the following bonding means.
That is, a WC-based cemented carbide member and a WC-based cemented carbide member are abutted with each other through a joining member, and a joining member having a low melting point is obtained by maintaining a prescribed temperature and time with a prescribed pressure applied. Once melted, it reacts with the WC-based cemented carbide component to form an alloy. And since the melting point rises when the alloy is formed, solidification starts at the joining temperature. As a result, it is a joining means in which a liquid phase does not appear at the joining temperature and a joining interface having excellent high temperature characteristics can be obtained.
When liquid phase diffusion bonding is performed between WC-based cemented carbide members using a bonding member, the bonding member has a low melting point (approximately 1000 ° C. or less) and is a binder phase component of the WC-based cemented carbide. Conditions such as solid solution with Co to form a high melting point alloy and excellent wettability with a WC-based cemented carbide are required.

Since the present invention performs liquid phase diffusion bonding of a WC-based cemented carbide member and a joining member, in the finally formed composite member, the components of the WC-based cemented carbide at the joint between the WC-based cemented carbides Although the composition will change, the average component composition of the WC-based cemented carbide in the joint part of the composite member, particularly the average component composition of the binder phase is Zn: 40 to 85 atomic% and Co: 15 to 60 atomic% In this case, the strength of the joint portion of the composite member is improved, and as a result, the strength of the composite member as a whole is also improved.
Here, the joint portion of the composite member refers to a region where the Zn content in the binder phase is 40 to 85 atomic% when the vicinity of the joint portion of the composite member is subjected to longitudinal section observation and point analysis of the composition. (See FIG. 1 (c)).

For the WC-based cemented carbide at the joint, if the average Zn content in the binder phase exceeds 85 atomic%, an alloy phase with a low Co content (for example, Zn _7.8 Co, Zn ₁₃ Co) appears. When the liquid phase appearance temperature is lowered to about 700 ° C. and the binder phase becomes brittle and is used at a high temperature, peeling of the joint portion is likely to occur. On the other hand, when the average Zn content is less than 40 atomic%, Since Co does not form an alloy phase, the strength of the joint cannot be increased.
Therefore, in this invention, the average component composition of the binder phase of the WC base cemented carbide in the joint part of a composite member shall be Zn: 40-85 atomic% and Co: 15-60 atomic%.

In order to form a composite member having a joint portion having the above average component composition, for example, a joining member made of Zn foil having a thickness of 10 μm and a purity of at least 98 atomic% is used. The WC-based cemented carbide member is interposed between the WC-based cemented carbide members, the WC-based cemented carbide member is pressed between the WC-based cemented carbide members by applying a pressure of 500 to 5000 kPa, It can be produced by liquid phase diffusion bonding with a bonding member.
Since the composite member produced in this way is bonded by liquid phase diffusion bonding between the WC-based cemented carbide member and the bonding member, the joint between the WC-based cemented carbide member and the WC-based cemented carbide member. Finally, the joining member does not remain as an independent layer.
Here, when the Zn purity of the Zn foil that is the bonding member is less than 98 atomic%, the impurity component contained in the bonding member when the WC-based cemented carbide members are pressure bonded to each other via the bonding member. Zn is inhibited by diffusion, and Zn foil remains as a Zn layer at the joint between the WC-based cemented carbide members, or the Zn-Co alloy having a low Co content (for example, Zn _7.8 Co, Zn ₁₃ Co) is formed, and the strength of the joint portion is reduced. Therefore, the purity of the Zn foil as the joining member is desirably 98 atomic% or more.

The conditions for liquid phase diffusion bonding are preferably 1500-3500 kPa for pressing the WC-base cemented carbide members through the bonding members, and heating at 500-700 ° C. for 5 to 120 minutes. .
Further, in order to sufficiently liquid phase diffusely bond the bonding portion and not leave a Zn layer in the bonding portion or to form a Zn-Co alloy having a low Co content, the purity of the Zn foil is set to 98 atomic%. In addition to the above, it is desirable that the thickness of the Zn foil as the joining member is 5 to 15 μm.

The composite member of the present invention can constitute a cutting tool by using one of the composite members as a WC-based cemented carbide member on the side of the cutting edge and using the other WC-based cemented carbide member as a tool base.
For example, by using one WC-based cemented carbide member of the composite member as a backing material of a cBN sintered body on the cutting edge side and the other WC-based cemented carbide member as a tool base (base metal), A cBN cutting tool can be formed.

The joint part of the composite member of the present invention is observed in a longitudinal section using a scanning electron microscope and an energy dispersive X-ray spectrometer, and is perpendicular to the butt surface (joint interface) between WC-based cemented carbides. Within a range of ± 50 μm in the direction, a straight line parallel to the butt surface (bonding interface) is drawn so that each straight line has an interval of 1 μm. Subsequently, with a field of view of 5000 times, 5 points were measured on the bonded phase on each straight line, and the measurement results of 5 points were averaged to obtain Zn and Co components of the bonded phase on each straight line. The average composition (average content of each element) can be determined.
And the area | region where Zn is contained 40 atomic% or more is identified from content of Zn in the binder phase on each straight line, and this area | region thickness can be calculated | required as thickness of a junction part.

  The average composition (average content of each element) of the components Zn and Co in the joint part of the composite member of the present invention was observed by using a scanning electron microscope and an energy dispersive X-ray spectrometer, and the joint part was observed in a longitudinal section. It can be obtained by averaging the components of the binder phase on each straight line in the joint.

The present invention is a composite member in which a WC-based cemented carbide member and a WC-based cemented carbide member are bonded by liquid phase diffusion bonding, preferably through a bonding member made of a Zn foil containing 98 atomic% or more of Zn. In addition, since the average component composition of the binder phase of the WC-based cemented carbide in the joint is composed of Zn: 40 to 85 atomic% and Co: 15 to 60 atomic%, the strength of the joint is excellent. As a result, the composite member The overall strength is also improved.
Therefore, even when the cutting tool composed of the composite member is subjected to heavy cutting in which a high load acts on the cutting edge, damage from the joint portion does not occur, and it can be used over a long period of use. Exhibits excellent cutting performance.

It is the schematic diagram which showed the preparation process of the composite member of this invention, Comprising: (a) is before joining, (b) is at the time of liquid phase diffusion joining, (c) shows the composite member after joining.

  Next, the present invention will be specifically described based on examples. In addition, the Example demonstrated below is one embodiment of this invention, Comprising: Specific embodiment of this invention is not restrict | limited to this.

As raw material powders, WC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder and Co powder all having an average particle diameter of 0.5 to 1 μm were prepared. These raw material powders are shown in Table 1. It is blended into the blended composition, wet mixed in a ball mill for 24 hours, dried, and then pressed into a green compact at a pressure of 100 MPa, and this green compact is vacuumed at 6 Pa, temperature 1400 ° C., holding time 1 hour. Sintering was performed under the conditions to form four types of WC-based cemented carbide sintered bodies (hereinafter simply referred to as “superhard alloys”) A-1 to A-4 shown in Table 1.

Next, cBN powder, TiN powder, TiCN powder, TiB ₂ powder, TiC powder, AlN powder, Al ₂ O each having an average particle size in the range of 0.5 to 4 μm as the raw material powder of the cBN sintered body ₃ powders were prepared, these raw material powders were blended in a prescribed composition, wet mixed with acetone for 24 hours in a ball mill, dried, and then pressure having a size of 15 mm diameter × 1 mm thickness at 100 MPa pressure. Press-molded into powder.
Next, the cemented carbides A-1 to A-4 are made into a sintered body having a size of 15 mm in diameter and 2 mm in thickness, and this is used as a backing material during sintering of the cBN sintered body, and the cBN is placed on the backing material. The green compacts were laminated in the combinations shown in Table 2, and this laminate was then sintered using an ultrahigh pressure generator at a temperature of 1300 ° C., a pressure of 5.5 GPa, and a time of 30 minutes. Sintered bodies B-1 to B-4 were produced.
Regarding the composition of the cBN sintered bodies of the composite sintered bodies B-1 to B-4, the area% of cBN was determined as the volume% by image analysis of the SEM observation result of the cross-section polished surface of the cBN sintered body.
About components other than cBN, it stopped only to confirm the component which comprises the main binder phase and other binder phases. The results are shown in Table 2.

  Next, Zn foil shown in Table 3 was prepared as a bonding member.

  Subsequently, the joining members shown in Table 3 are inserted between the cemented carbides A-1 to A-4 and the composite sintered bodies B-1 to B-4, and the composite sintered body is subjected to the conditions shown in Table 4. The present invention composite members 1 to 9 shown in Table 7 were produced by pressure bonding the cemented carbide and the cemented carbide. Note that the composite sintered body is such that the cBN sintered body is the outer surface and the backing material is the inner surface, that is, the WC-based cemented carbide that is the backing material and the WC-based cemented carbide that is the tool base (base metal) are the bonding members. It arrange | positioned so that it might join.

  For comparison, a joining member having the component composition and size shown in Table 5 is prepared, and this is placed between the cemented carbides A-1 to A-4 and the composite sintered bodies B-1 to B-4. The composite sintered body and the cemented carbide were pressure bonded under the conditions shown in Table 6 under the conditions shown in Table 6 to produce comparative example composite members 1 to 10 shown in Table 8. The joint arrangement of the composite sintered body was the same as that of the composite member of the present invention.

High temperature shear strength measurement test:
The present invention composite members 1-9 and comparative example composite members 1-10 produced above were subjected to a shear strength measurement test in order to measure the strength of the joint.
The test pieces used for the test were composite sintered bodies: 1.5 mm (W) × 1.5 mm (L) × 0. 75 mm (H), WC-based cemented carbide substrate (base metal): 1.5 mm (W) x 4.5 mm (L) x 1.5 mm (H) cut out to obtain a shear strength measurement specimen It was.
The upper and lower surfaces of the test piece are clamped and fixed, and a prismatic pressing piece made of cemented carbide with a side of 1.5 mm is used. The ambient temperature is set to 600 ° C., and a load is applied near the center of the upper surface of the test piece. The load at which the test piece breaks was measured.
Tables 7 and 8 show the measured shear strength values.

Moreover, about this invention composite members 1-9 and comparative example composite members 1-10, the composition analysis of the longitudinal cross-section of a WC base cemented carbide and a junction part is performed using a scanning electron microscope and an energy dispersive X-ray spectrometer. went.
Within a range of ± 50 μm in the direction perpendicular to the butt surfaces (bonding interface) between the WC-base cemented carbides, a straight line parallel to the butt surface (bonding interface) is drawn so that each straight line has an interval of 1 μm, Subsequently, with a field of view of 5000 times, 5 points were measured on the bonded phase on each straight line, and the measurement results of 5 points were averaged to obtain Zn and Co components of the bonded phase on each straight line. The average composition (average content of each element) was determined.
And the thickness of the area | region in which Zn contained 40 atomic% or more in a binder phase was calculated | required as the thickness of a junction part.
Tables 7 and 8 show the results.

Next, cutting tools composed of the composite members 1 to 9 of the present invention and the comparative composite members 1 to 10 were produced, and the presence or absence of breakage in the cutting process was investigated.
A cutting tool made of a composite member was produced as follows.
The composite sintered bodies B-1 to B-4 produced above were cut into a plane shape: an isosceles triangle with an opening angle of 80 ° having a side of 4 mm × thickness: 2 mm. Subsequently, the cemented carbides A-1 to A-4 are formed into a sintered body having a planar shape: an inscribed circle of 12.7 mm and an open angle of 80 ° × thickness: 4.76 mm. A notch having a size corresponding to the shape of the composite sintered body was formed in one corner of any one of the upper and lower parallel surfaces of the bonded body using a grinding machine. The area of the bottom surface of this notch is 2.96 mm ² and the area of the side surface is 4.89 mm ² . Subsequently, the joining members shown in Table 3 are inserted between the cemented carbides A-1 to A-4 and the composite sintered bodies B-1 to B-4, and the composite sintered body is subjected to the conditions shown in Table 4. And the WC base cemented carbide are pressure bonded, and after cutting the outer periphery of this composite member, the cutting edge portion is subjected to a honing process of R: 0.07 mm to have an ISO standard / CNGA120408 insert shape. Tools 1-9 were produced.
The composite sintered body was arranged so that the cBN sintered body was the outer surface and the backing material was the inner surface, that is, the backing material and the tool base (base metal) were joined via the joining member.
Moreover, it confirmed that the junction part of these invention cutting tools 1-9 was substantially the same as this invention composite members 1-9 shown in Table 7.
Similarly, the joining members shown in Table 5 are inserted between the composite sintered bodies B-1 to B-4 produced above and the cemented carbides A-1 to A-4 produced above, Pressure bonding was performed under the conditions shown in FIG.
Moreover, it confirmed that the junction part of these comparative example cutting tools 1-10 was substantially the same as the comparative example composite members 1-10 shown in Table 8.

Next, it shows below about this invention cutting tool 1-9 and comparative example cutting tool 1-10 in the state which screwed all the said various cutting tools to the front-end | tip part of the tool steel tool | tool with the fixing jig. A dry high-speed heavy cutting test of carburized and hardened steel was performed, and the location of the blade tip falling off and fractured portion was observed.
Work material: JIS / SCM415 (hardness: 58HRc) round bar,
Cutting speed: 255 m / min. ,
Cutting depth: 0.5 mm,
Feed: 0.4 mm / rev. ,
Cutting time: 18 minutes
(Normal cutting speed and feed are 150 m / min and 0.2 mm / rev., Respectively)
Table 9 shows the cutting test results.

From the values of the shear strength shown in Tables 7 and 8, it can be seen that the composite members 1 to 9 of the present invention have superior bonding strength as compared with the composite members 1 to 10 of the comparative example.
Further, from the results shown in Table 9, the cutting tools 1 to 9 of the present invention composed of the composite members 1 to 9 of the present invention exhibit excellent cutting performance over a long period of use without the removal of the cutting edge. On the other hand, it can be seen that the comparative cutting tools 1 to 10 constituted by the comparative composite members 1 to 10 cause the cutting edge to fall off from the joint during cutting, leading to early tool life.

  In the present embodiment, the insert has been specifically described as an example. However, the present invention is not limited to the insert, and all cutting tools having a joint between the cutting edge portion and the tool body, such as a drill and an end mill. Needless to say, the present invention is applicable to drilling tools such as bits.

The composite member of the present invention has a high bonding strength, and the cutting tool produced from this composite member can be used for high-load cutting of various steels and cast irons, and is stable over a long period of time. Since the cutting performance is exhibited, it is possible to satisfactorily cope with high performance of the cutting device, labor saving and energy saving of the cutting work, and further cost reduction.

Claims (3)

A WC-based cemented carbide member and a WC-based cemented carbide member are composite members joined at a joint,
The joint has a thickness of 2 to 50 μm, and the binder phase of the WC-based cemented carbide in the joint has an average composition of Zn: 40 to 85 atomic% and Co: 15 to 60 atomic%. A composite member characterized by comprising:   The composite member is formed by pressure bonding via a bonding member between a WC-based cemented carbide member and a WC-based cemented carbide member, and the bonding member contains 98 atomic% or more of Zn. The composite member according to claim 1, wherein the composite member is a Zn foil. A tool comprising the composite member according to claim 1.