JP2502364B2 - High hardness sintered body for tools - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to improvement of a high hardness sintered body for tools using cubic boron nitride (hereinafter referred to as cBN).

[Conventional technology]

cBN is a high hardness material next to diamond, and its sintered body is used in various cutting tools. For this type of cBN sintered body, which is suitable for cutting tools, for example, 70% by volume
% Or more of cBN particles bonded by a metal phase containing Al and at least one alloying element selected from the group consisting of Ni, Co, Mn, Fe, V and Cr (Japanese Patent Laid-Open No. 17503/1978), 8% by volume
0-95% cBN particles with TiN or ZrN and Al-Ti or Al
-Zr intermetallic compound and further Al, cBN, TiN or ZrN
Those bonded by a binder phase composed of a heat-resistant compound formed by the reaction with (Japanese Patent Publication No. 58-55111), and 80 to 95% by volume of cBN particles are group IVa, Va, or group transition metal of the periodic table. Bound by a binder phase consisting of a heat-resistant compound formed by the reaction of the above-mentioned carbides, nitrides, and carbonitrides with Al, cBN, and Cu (JP-A-62-228403) and 80 to 80% by volume.
95% cBN particles are group IVa, carbides, nitrides,
There has been proposed a sintered body (Japanese Patent Publication No. 62-984) in which a carbon nitride is combined with Al, cBN, Cu, and a binder phase composed of a heat-resistant compound formed by reaction with an iron group metal.

[Problems to be Solved by the Invention]

However, even when the above-mentioned sintered body is used as a cutting tool, the wear resistance is lowered under cutting conditions in which the cutting edge has a high temperature such as high-speed cutting of heat-resistant alloy or cast iron, and the life thereof is relatively long. It had the drawback of being short.

Therefore, an object of the present invention is to provide a sintered body that is superior in wear resistance under cutting conditions where the cutting edge has a higher temperature than the conventional cBN sintered body described above and that enables high-speed cutting. .

[Means for solving the problem]

As a result of intensive studies to achieve the above objects, the present inventors have found that if cBN is contained in an amount of 70 to 95% by volume, and the balance is a mixed powder consisting of the following binders, it undergoes conventional high pressure sintering. The inventors have found that a cBN sintered body having excellent wear resistance under cutting conditions in which the cutting edge has a higher temperature than the body can be obtained and reached the present invention.

That is, the present invention contains 70-95% by volume of cBN powder,
A sintered powder obtained by sintering a mixed powder, the balance of which is binder powder, under high pressure and high temperature, wherein the binder is at least selected from the group consisting of Al and a compound of Al and Ti. 2 to 50% by weight (Al equivalent), W, WC and W and Ti
At least one kind 2 selected from the group consisting of compounds
~ 50 wt% (W conversion) and the balance TiN _z , TiC _z , Ti (N) _z ,
At least one Ti compound selected from the group consisting of (Ti, M) N _z , (Ti, M) C _z and (Ti, M) (C, N) _z (where M is Ti
Is a transition element of group IVa, Va, VIa of the periodic table excluding
z <0.45), the contained Ti and the periodic table
The atomic ratio of the transition metal element M of the IVa, Va, and VIa groups to Ti: M
= 67: 100 to 97: 100 for a high hardness sintered body for tools.

In the cBN sintered body of the present invention, c is contained in the produced sintered body.
In addition to BN, TiN, TiC, Ti (C, N), (Ti, M) N, (Ti, M) C and (Ti, M) (C, N) selected from the group consisting of one or more Ti At least one of a compound, titanium boride, the boride of M, aluminum boride, aluminum nitride, a tungsten compound and tungsten is included.

[Action]

The reason why the sintered body of the present invention has excellent wear resistance under cutting conditions where the cutting edge has a high temperature and is capable of high-speed cutting can be presumed to be as follows.

In general, the wear of the sintered body progresses due to the wear of the binder phase and the breakage of the cBN particles at the joint portion, causing the cBN particles to drop off. Therefore, in order to improve the wear resistance of the sintered body under cutting conditions where the cutting edge has a high temperature,
It is necessary that the cBN particles and the cBN particles are strongly bonded to the binder and that the binder itself has high strength. In the sintered body of the present invention, the presence of an Al compound in the binder is similar to the dissolution and reprecipitation phenomenon of hard particles in the binder phase such as liquid phase sintering of WC-Co cemented carbide. The phenomenon described above occurs, cBN particles are bonded to the binder and cBN particles to each other, and free Ti and Ti contained in the binder are excluded Ti and Ti-Al of transition metals of Group IVa, Va, and VIa of the periodic table. Ti and cBN in the intermetallic compound react during sintering at high temperature and high pressure, and T
It is considered that iB ₂ or the boride of M is generated, whereby the cBN particles and the binder are strongly bonded. That is,
In the binder phase of the sintered body of the present invention, in addition to Ti carbide, nitride and carbonitride, TiB ₂ , M boride and the like are included. Ti
B _{2 and} the boride of M are brittle and may be harmful under cutting conditions where the temperature of the cutting edge does not become too high, but when the cutting edge temperature becomes high, Ti carbide, nitride, carbonitride It is considered to be more stable than the above, and the strength and bonding strength of the binder phase at high temperature are not deteriorated, which is preferable.

TiN _z , TiC _z , Ti (C, N) _z , (Ti, M) N _z , (Ti, M) C _z , and (Ti,
One or more Ti compounds selected from the group consisting of M) (C, N) _z (provided that M is a transition metal element of Group IVa, Va, VIa of the periodic table excluding Ti, and 0 <z <0.45 Free Ti in) is preferable because it reacts with the cBN crystal to form TiB ₂ cheaply. The Z value in the above chemical formula is preferably 0 <z <0.45. When it is 0.45 or more, the amount of TiB ₂ produced decreases and the bonding strength decreases. On the other hand, metal Ti (Z =
In the case of 0), the pulverization cannot be sufficiently performed at the time of producing the binder powder, and the sinterability decreases. The above Ti nitrides and carbonitrides have periodic table IV
When a nitride or carbonitride of a, Va or VIa group transition metal is dissolved or mixed, the strength of the binder is increased, and the characteristics are further improved as compared with the case where only the Ti compound is used as the binder. The Ti content in this binder is Ti and Ti, Periodic Table IVa,
The atomic ratio of Va and VIa group metal elements M is Ti: M = 67: 100-9
It needs to be 7: 100. Ti content is Ti: M = 67:
When it is less than 100, the binder of the binder and cBN is reduced, which is not preferable. On the other hand, when the above atomic ratio exceeds Ti: M = 97: 100, the wear resistance and strength of the binder decrease.

The content of Al or Al-Ti intermetallic compound in the binder needs to be 2 to 50% by weight (Al equivalent). If the Al content is less than 2% by weight, the effect of the addition is insufficient, and if it exceeds 50% by weight, the hardness of the binder decreases. It is preferably 10 to 30% by weight.

WC or W compound is added especially to improve wear resistance, and the content in the binder is 2 to 50% by weight.
(W conversion). If the W content is less than 2% by weight, the wear resistance cannot be improved. On the other hand, if it exceeds 50% by weight, the content of the Ti compound decreases, and the bonding strength between the cBN and the binder decreases. Absent. In particular, when W is used as M in the above chemical formula, the wear resistance and strength of the binder are improved and good properties are exhibited.

In the sintered body of the present invention, the cBN particles are bound by the binder phase made of the above-mentioned binder. cBN particle content is 70
It is preferably less than 95% by volume. If it is less than 70% by volume, the hardness of the sintered body, especially the high-temperature strength will decrease, which is not preferable.
If the cBN content exceeds 95% by volume, the toughness of the sintered body decreases, which is not preferable.

〔The invention's effect〕

In the present invention, cBN particles are obtained by mixing a binder containing a Ti compound, Al, WC, etc. with cBN and sintering the mixture at ultrahigh pressure and high temperature.
In addition to containing 0 to 95% by volume, the remaining binder contains 2 to 50% by weight of Al component to form aluminum boride, aluminum nitride and the like, and the binder contains 2% of W component. ˜50% by weight, which is present as WC, W compounds, etc., and further contains Ti carbide, nitride, carbonitride, etc., so the strength of the binder is high, and cBN and binder or It is possible to obtain a sintered body for a high hardness tool in which the bonding strength of the binder itself is excellent. In particular, the sintered body of the present invention is excellent in strength at high temperatures and therefore suitable for applications such as high-speed cutting of heat-resistant alloys and cast iron.

Example 1 A nitride or carbonitride powder containing Ti was mixed with an aluminum powder and a WC powder, and the mixture was mixed with a cemented carbide pot and a ball having a first average particle size of 1 μm or less.
A binder powder having the composition shown in the table was prepared. The volume ratio of these binder powders to cBN powders with a particle size of 3 μm or less is 2
Mixing was carried out so as to be 0 to 80 to prepare a mixed powder. A disk made of cemented carbide with a WC-10 wt% Co composition was placed in a container made of Mo, and then a mixed powder of these was filled. Next, the container was put into an ultrahigh pressure, high temperature apparatus and sintered at a pressure of 54 kb and 1400 ° C. for 25 minutes.

The X-ray diffraction results of the obtained sintered body are shown in Table 2. Peaks of nitrides, carbides and carbonitrides containing cBN and Ti were observed in all the sintered bodies. In addition to the above substances, Ti
Other than B ₂ and Ti, boride of transition metal M of Group IVa, Va, VIa of the periodic table, boride of A1B2, A1N and W, peaks thought to be carbides or W were observed.

In addition, Table 3 shows the results of measuring the Vickers hardness of these sintered bodies.

Next, these sintered bodies were processed into chips for cutting, and Incoloy 901 (Incoloy 901) was cut under cutting conditions of a cutting speed of 240 m / min, a depth of cut of 0.15 mm, and a feed of 0.08 mm / rev. Table 3 shows the time when cutting was possible. The atomic ratio [Ti: M] shown in Table 1 is the atomic ratio of Ti to the transition metal elements of Groups IVa, Va, and VIa of the periodic table.

Example 2 (Ti _0.9 W _0.1 ) (C _0.2 , N _0.8 ) _0.3 , Al and WC powder were mixed to obtain a binder powder having a particle size of 1 μm or less. The composition of this binder powder is 76% (Ti _0.9 Zr _0.1 ) (C _0.5 N _0.5 ),% by weight.
It is _{0.3 -12% Al-12% WC} . In addition, Ti and W in the binder
The atomic ratio of is 88.5 to 14.5. This binder powder and cBN powder were mixed as shown in Table 4 to prepare a mixed powder.

The obtained mixed powder was subjected to ultra high pressure sintering in the same manner as in Example 1 to obtain a sintered body. Table 4 shows the results of Vickers hardness measurement of the obtained sintered body.

Next, these sintered bodies were processed into chips for cutting, and SKD11 (H _RC 60) was cut. Cutting conditions are cutting speed 190m / min. Depth of cut / mm,
The feed is 0.5 mm / rev dry type. Table 4 shows the time when cutting was possible.

Example 3 (Ti _0.9 Zr _0.1 ) (C _0.5 N _0.5 ) _z with different Ti compounds having different Z values
Al and WC powders were mixed to prepare a binder powder having a particle size of 1 μm or less. The composition of these binder powders is 75% by weight (Ti
_0.9 Zr _0.1 ) (C _0.5 N _0.5 ) _z -15% Al -10% WC-.

Table 5 shows the Z values of the Ti compounds of these binders and Ti
To the transition metal elements of groups IVa, Va, and VIa of the periodic table [T
i: M] is shown.

These binder powders and cBN powder having a particle size of 3 μm or less were mixed at a volume ratio of 25:75 to obtain a mixed powder. These mixed powders were put into a container made of Mo and subjected to ultra-high pressure sintering. In addition,
Sintering was performed by maintaining at 50 Kb and 1350 ° C. for 30 minutes.

Table 6 shows the Vickers hardness measurement results of these sintered bodies.

Next, these sintered bodies were processed into chips for cutting, and Rene 41 (trade name-Nickel base super alloy) was cut. The cutting conditions are: cutting speed: 180 m / min, depth of cut: 0.12 mm, feed: 0.1 mm / rev, dry type. Table 6 shows the time when cutting was possible.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C22C 29/02 C04B 35/58 103H

Claims (3)

(57) [Claims] 1. A sintered body obtained by sintering a mixed powder containing 70 to 95% by volume of cubic boron nitride powder and the remainder being binder powder at ultrahigh pressure and high temperature. Binder is Al
And 2 to 50% by weight (as Al), W, WC and W selected from the group consisting of Al and Ti compounds.
At least one selected from the group consisting of compounds with Ti 2 to 50% by weight (in terms of W) and the balance TiN _z , TiC _z , Ti (C,
N) _z , (Ti, M) N _z , (Ti, M) C _z and at least one Ti compound selected from the group consisting of (Ti, M) (C, N) _z (provided that M
Is a transition element of the IVa, Va, and VIa groups of the periodic table excluding Ti,
0 <z <0.45), and the ratio of the contained Ti and the transition metal element M of the IVa, Va, or VIa group of the periodic table is an atomic ratio.
High hardness sintered compact for tools with Ti: M = 67: 100 to 97: 100. 2. The sintered body is made of Ti in addition to cubic boron nitride.
N, TiC, Ti (C, N), (Ti, M) N, (Ti, M) C and (Ti,
At least one selected from the group consisting of M) (C, N)
The high hardness sintered body for a tool according to claim (1), comprising at least one of a Ti compound, titanium boride, the boride of M, aluminum boride, aluminum nitride, a W compound and W. 3. The high hardness sintered body for a tool according to claim 1, wherein M is tungsten.