JPH02236253A - High hardness sintered body for tool - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] 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 hard substance second only to diamond, and its sintered bodies are used in various cutting tools.

This type of cBN sintered body suitable for cutting tools is, for example, made by combining cBN particles of 70% or more by volume with Al and Ni,
Co, Mn. Bonded by a metal phase containing at least one alloying element selected from the group consisting of Fe, V, and Cr (Japanese Unexamined Patent Publication No. 48-17503), cBN of 80 to 95% by volume The particles can be made of intermetallic compounds of TiN or ZrN and ^1-Ti or 81-Zr and also 81, cBN, TiN or Zr.
cBN particles of 80 to 95% by volume are bonded by a binder phase made of a heat-resistant compound formed by reaction with N (Japanese Patent Laid-Open No. 58-55111), and cBN particles of 80 to 95% by volume are
Va, Va group transition metal carbides, nitrides, carbonitrides and ^
1, bonded by a bonding phase made of a heat-resistant compound formed by reaction with cBN and Cu (Japanese Unexamined Patent Application Publication No. 1983-1999)
-22840) and 80 to 95% c by volume%.
A sintered body (particularly JP-A-62-984) and the like have been proposed.

[Problem to be solved by the invention]

However, even when the above-mentioned sintered body is used as a cutting tool, the wear resistance decreases under cutting conditions where the cutting edge becomes hot, such as when cutting heat-resistant alloys or cast iron at high speed, resulting in a relatively short life. It had the disadvantage of being short.

Therefore, an object of the present invention is to provide a sintered body which has better wear resistance under cutting conditions where the cutting edge becomes hot than the conventional cBN sintered body described above, and which enables high-speed cutting.

[Means to solve the problem]

As a result of intensive research by the present inventors to achieve the above object, we found that if a mixed powder containing 70 to 95% by volume of cBN and the balance consisting of the following binder is sintered under ultra-high pressure, it is possible to achieve the conventional cBN.
The present invention was achieved by discovering that it is possible to obtain a cBN sintered body that has better wear resistance under cutting conditions where the cutting edge becomes hotter than a N sintered body.

That is, the present invention provides a sintered body obtained by sintering a mixed powder containing 70 to 95% by volume of cBN powder and the remainder consisting of binder powder under ultra-high pressure and high temperature, wherein the binder is A.
2 to 50% by weight (in terms of Al) W, WC of at least one selected from the group consisting of compounds of 1 and A1 and Ti
and 2 to 50% by weight (in terms of W) of at least one selected from the group consisting of compounds of W and Ti, and the remainder is T.
iNz, TiCz, Ti(C,N)z, (Ti
, M)Nz, (Ti,M)Cz and (Ti,M
) (C, N) At least one Ti compound selected from the group consisting of z (where M is a transition element in groups IVa, Va, and VIa of the periodic table excluding Ti, and Q<z
<0.45), and the ratio of the contained Ti to the transition metal element M of groups IVa, Va, and VIa of the periodic table is Ti:M = 67:100 to 97:100 in atomic ratio This invention relates to a high hardness sintered body for tools.

In the cBN sintered body of the present invention, in addition to cBN, TiN, Tic, Ti(C, N),
(Ti,M)N, <Ti,M)C and (Ti
, M) Contains one or more Ti compounds selected from the group consisting of (C, N), titanium boride, the boride of M, aluminum boride, aluminum nitride, a tungsten compound, and tungsten. .

[For production]

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

Generally, abrasion of a sintered body progresses as cBN particles fall off due to abrasion of the binder phase and fracture at the joints of cBN particles. Therefore, in order to improve the wear resistance of a sintered body under cutting conditions where the cutting edge becomes hot, it is necessary to ensure that the cBN particles are firmly bonded to each other and the cBN particles and the binder at high temperatures, and that the strength of the binder itself is It needs to be high. In the sintered body of the present invention, by making the ^l compound exist in the binder, the phenomenon of dissolution and reprecipitation of hard particles in the binder phase is similar to that in liquid phase sintering of WC-Co cemented carbide. phenomenon occurs, cBN particles, binder and cBN
Periodic table IVa, Va, and V excluding free Ti and Ti, where particles are bonded to each other and contain Ti compounds in the binder.
Group Ia transition metal M and T in Ti-Al intermetallic compound
i and cBN react during sintering under high temperature and pressure, resulting in TI82
It is thought that the cBN particles and the binding material are strongly bonded together by forming boride of the above-mentioned M. That is,
The binder phase of the sintered body of the present invention contains Ti carbides, nitrides,
In addition to carbonitride, TI82, the boride of M mentioned above, etc. are also included. Borides such as TiB2 and M mentioned above are brittle and may be harmful under cutting conditions where the temperature of the cutting edge does not become too high, but when the temperature of the cutting edge becomes high, carbides of TI,
It is considered to be more stable than nitrides and carbonitrides, and is preferable because the strength and bonding force of the binder phase at high temperatures do not decrease.

TiNz, TiCz, Ti(C,N)z, (T
i,M)Nz, (Ti,M)Cz and (Ti,
M) (C, N) One or more Ti compounds selected from the group consisting of
It is a transition metal element of the a, Va, VTa group, and Q < z
Free Ti in <0.45) reacts with cBN crystals and
It is preferable to produce TiB2. The Z value in the above chemical formula is preferably O<Z<0.45. Above 0.45, Ti
The amount of B2 produced decreases and the binding strength decreases. On the other hand, metal T
In the case of i (Z=O), sufficient pulverization is not possible during the preparation of the binder powder, resulting in a decrease in sinterability. If nitrides and carbonitrides of transition metals from groups IVa, Va, and Vla of the periodic table are dissolved or mixed with the Ti nitrides and carbonitrides mentioned above, the strength of the binder increases, and only Ti compounds are bonded. The properties are further improved than when used as a material. The Ti content in this bonding material is such that the atomic ratio of Ti and M, a metal element of groups IVa, Va, and VIa of the periodic table, is Ti:M=67+100~
It is necessary that the ratio be 97:100. If the Ti content is less than Ti:M=67:100, the bonding agent between the binder and cBN will deteriorate, which is not preferable. On the other hand, if the atomic ratio exceeds Ti:M=97:100, the wear resistance and strength of the binder will decrease.

The content of A1 or Al-Ti intermetallic compound in the binder needs to be 2 to 50% by weight (in terms of Al). When the content of A1 is 2% by weight without swirling, the effect of its addition is insufficient, and when it exceeds 50% by weight, the hardness of the binder decreases. Preferably it is 10 to 30% by weight.

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

In the sintered body of the present invention, cBN particles are bonded by a binder phase made of the above-mentioned binder.

The content of cBN particles is preferably 70 to 95% by volume. 7
If the local cBN content is less than 0% by volume, the hardness of the sintered body, especially high-temperature strength, will decrease, which is undesirable, and if the local cBN content exceeds 95% by volume, the toughness of the sintered body will decrease, which is undesirable.

〔Effect of the invention〕

In this invention, cBN is obtained by mixing a binder containing a Ti compound, A1, WC, etc. and sintering it under ultra-high pressure and high temperature.
In addition to containing 70 to 95% by volume of N particles, the remaining binder contains 2 to 50% by weight of the ^1 component, forming aluminum boride, aluminum nitride, etc., and the binder also contains The W component is contained in an amount of 2 to 50% by weight, which is WC.
It exists as a 1W compound, etc., and also contains Ti carbides, nitrides, carbonitrides, etc., so the strength of the binder is high (i.e., the bonding strength between cBN and the binder or the binder itself is excellent). A sintered body for hard tools can be obtained. In particular, the sintered body of the present invention has excellent strength at high temperatures and is therefore suitable for applications such as high-speed cutting of heat-resistant alloys and cast iron.

Example I Ti-containing nitride or carbonitride powder, aluminum powder and WC powder are mixed and mixed using a cemented carbide pot and ball to form the composition shown in Table 1 with an average particle size of 1 μm or less. A binder powder having the following properties was prepared. These binder powders and cBN powder with a particle size of 3 μm or less were mixed at a volume ratio of 20:80 to create a mixed powder. A disk made of cemented carbide having a composition of WC-10 wt % Co was placed in a container made of Mo, and then the mixed powders were filled therein. Next, the container was placed in an ultra-high pressure, high temperature device, and the pressure was 54k.
b. Sintered at 1400°C for 25 minutes.

Table 2 shows the X-ray diffraction results of the obtained sintered body. Peaks of nitrides, carbides, and carbonitrides containing cBN and Ti were observed in all the sintered bodies. In addition to the above substances,
Periodic table 1'Va, Va, VI other than TiB2 and Ti
Peaks that appeared to be borides of group a transition metals M, AlB2, AlN, and W borides, carbides, or W were observed in S.

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

Next, these sintered bodies were processed to make cutting chips using Incoloy 90H Incoloy 901) at a cutting speed of 240 m/min, depth of cut of 0.15 mm, and feed of 0. 08
Cutting was performed under the cutting conditions of mm/rev. Table 3 shows the time during which cutting was possible. Note that the atomic ratio [T
i:M] is Ti and rVa. of the periodic table. The atomic ratio with Va and group VIa transition metal elements is shown.

Table 2 (continued) Table 2 obtained. The composition of this binder powder is 76% (T
io. sZro. +) (Co.s N0.5) 0.3
-12% Al-12% WC. Note that the atomic ratio of Ti and W in the binder is 88.5:14.5. This binder powder and cBN powder were mixed as shown in Table 4 to create 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 the Vickers hardness measurement of the obtained sintered body.

Next, these sintered bodies were processed into chips for cutting, and S K Dll (H.. 60) was cut. Cutting conditions: cutting speed 190m/min, depth of cut/mm
, a dry type with a feed rate of 0.5 mm/rev. Table 4 shows the times during which cutting was possible.

Example 2 (T+os. Wo. 1) (Co. 2 No.
a) Mix O-3, Al and WC powder and add binder powder with a particle size of 1 μm or less as shown in Table Example 3 (Tio. s Zro. +) (Co. s No.
．． s) Ti compounds with different values of Z and Al, WC
The powders were mixed to produce a binder powder with a particle size of 1.im or less. The composition of these binder powders is 75% by weight (Ti
、． = 2r. ．． 1) (Co.s No.s) 2
15% Al-10% WC.

Table 5 shows the Z value of the Ti compound of these binders and the Ti
The atomic ratio [Ti:ME] of the transition metal elements of groups IVa, Va, and VIa of the periodic table is shown.

These binder powders and cBN powder having a particle size of 3 Frn or less were mixed at a volume ratio of 25:75 to obtain a mixed powder.

These mixed powders were placed in a container made of Mo and sintered under ultra-high pressure. Note that sintering was performed by maintaining the temperature at 50 Kb and 1,350° C. for 30 minutes.

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

Next, these sintered bodies were processed into chips for cutting, and Rene 41 (trade name: nickel-based superalloy) was cut. The cutting conditions were: cutting speed: 180 m/min, depth of cut: 0.12 mm, feed: 0.
．． 1mm/rev, dry method.

Table 6 shows the time during which cutting was possible.

Claims (3)

[Claims] (1) A sintered body obtained by sintering a mixed powder containing 70 to 95% by volume of cubic silicon nitride powder and the remainder consisting of binder powder under ultra-high pressure and high temperature, wherein the Material is A
2 to 50% by weight (in terms of Al) of at least one selected from the group consisting of compounds of Al and Ti, W, W
2 to 50% by weight (in terms of W) of at least one selected from the group consisting of compounds of C and W and Ti, and the remainder is TiNz, TiCz, Ti(C,N)Z, (Ti,M)
Nz, (Ti,M)Cz and (Ti,M)(C,N)
At least one Ti compound selected from the group consisting of
It is a transition element of Group Ia, 0<z<0.45), and contains Ti and elements of the periodic table IVa, Va, and VIa.
The ratio of transition metal element M in the group is Ti:M=67 in atomic ratio
:100-97:100 High hardness sintered body for tools. (2) The sintered body contains TiN in addition to cubic boron nitride.
, TiC, Ti(C,N), (Ti,M)N, (Ti,
M) at least one Ti compound selected from the group consisting of C and (Ti,M)(C,N), titanium boride, the boride of M, aluminum boride, aluminum nitride,
Claim (1) containing at least one type of W compound and W
High hardness sintered body for tools described in . (3) Claim (1) or (
2) High hardness sintered body for tools.