JPH08229708A - Cubic boron nitride system super high pressure compound ceramics sintered compact and cutting tool - Google Patents

Abstract

PURPOSE: To prevent the generation of any damage to a surface member which is a cutting edge part, even in the case of high speed cutting of a high hard steel, cast iron, etc., by containing cobalt tungsten carbide in a support member made of tungsten carbide radical cemented carbide. CONSTITUTION: The constitutional component composition of a surface member consisting of a CBN contained ceramics sintered compact in a compound sintered compact is composed of CBN, 10-50 volume %, WC: 0.1-1 volume %, AlN, 3-7 volume %, TiB2 , 1-5 volume %, Al2 O3 , 3-10 volume %, one kind or two kinds or more out of TiC, TiN, TiCN and an inevitable impurities and remnants. Further, the constitutional component composition of the support member made of WC radical cemented carbide is composed of Co, 25-45 volume %, WC and the inevitable impurities and remnants. A cubic boron nitride system super high pressure compound ceramics sintered compact and a cutting tool are obtained by joining this surface member with the support member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a surface member made of a ceramic sintered body containing cubic boron nitride (hereinafter referred to as cBN) and a support member made of tungsten carbide (hereinafter referred to as WC) -based cemented carbide. The present invention relates to a cubic boron nitride-based ultra-high pressure composite ceramics sintered body (hereinafter referred to as a composite sintered body) and a cutting tool.

[0002]

2. Description of the Related Art A composite sintered body composed of a surface member made of a cBN-containing ceramics sintered body and a support member made of a WC-based cemented carbide is normally used, for example, in one corner of a throw-away tip made of a cemented carbide. It is well known that a throw-away tip brazed with a composite sintered body is attached to the cutting edge of a cutting tool to be used as a cutting tool (for example, JP-A-56-69283). reference).

The surface member of this conventional composite sintered body is cB.
N: contained in excess of 50% by volume, and the others include nitrides of 4a, 5a and 6a in the periodic table.

These composite sintered bodies are cBs which are surface members.
It is manufactured by joining an N-containing ceramics sintered body and a WC-based cemented carbide serving as a supporting member and sintering them under high temperature and high pressure.

[0005]

However, by using a cutting tool brazed with a conventional composite sintered body in which the surface member thus manufactured and the supporting member are joined, for example, high hardness steel, When high-speed cutting of cast iron or the like is performed, there is a problem that the surface member, which is the cutting edge portion, is damaged, flank wear is greatly developed, and the life is reached in a relatively short time.

[0006]

Therefore, the present inventors have
From this viewpoint, for example, as a result of research to obtain a composite ceramics sintered body having higher fracture resistance than high-speed cutting for high-hardness steel, cast iron and the like, cBN has been obtained.
And the binder phase is WC:
0.1 to 1% by volume, aluminum nitride (hereinafter referred to as AlN
3 to 7% by volume, titanium boride (hereinafter, referred to as TiB ₂₎
1 to 5% by volume, aluminum oxide (hereinafter referred to as A
l ₂ O ₃ ): 3 to 10% by volume, titanium carbide (hereinafter referred to as TiC), nitride (hereinafter referred to as TiN),
One or more of carbonitrides (hereinafter, referred to as TiCN) and inevitable impurities: surface member consisting of the balance, cobalt (hereinafter, referred to as Co): 25 to 45% by volume
A composite sintered body containing a cemented carbide support member containing WC and the rest consisting of unavoidable impurities, preferably cBN having an average particle size of 4 to 20 μm, and more preferably TiC or TiN. , TiCN have an average particle size of 1 μm or less, and WC, A
The average particle diameters of 1N, TiB ₂ and Al ₂ O ₃ are all 0.
It has been found that when the composite sintered body having a size of 5 μm or less is used for high-speed cutting of high hardness steel, cast iron, etc., for example, the cutting edge is less likely to be broken than in the conventional case and the cutting life is improved.

The present invention has been made on the basis of such findings, and in a composite sintered body in which a surface member made of a cBN-containing ceramics sintered body and a WC-based cemented carbide support member are joined, the above-mentioned cBN is used. The constituent composition of the surface member made of the contained ceramics sintered body is as follows: cBN: 10 to 50% by volume, WC: 0.1 to 1% by volume,
AlN: 3 to 7% by volume, TiB ₂ : 1 to 5% by volume, Al ₂
O ₃ : 3 to 10% by volume, one or more of TiC, TiN, and TiCN, and inevitable impurities: the balance, and the constituent composition of the above WC-based cemented carbide support member is Co: The present invention is characterized by a cubic boron nitride-based ultra-high pressure composite ceramics sintered body obtained by joining a WC-based cemented carbide support member consisting of 25 to 45% by volume, WC and unavoidable impurities: balance, and a cutting tool. .

The average particle size of cBN of the surface member is 4 to
20 μm is preferable. Further, T of the binder phase of the surface member
The particle size of one or more of iC, TiN, and TiCN is an average particle size of 1 μm or less, and WC and Al.
The particle sizes of N, TiB ₂ , and Al ₂ O ₃ are all average particle sizes:
It is preferably 0.5 μm or less.

The reason why the composite sintered body of the present invention is excellent in fracture resistance as compared with the conventional composite sintered body is that the conventional composite sintered body has a surface member made of cBN-containing ceramics sintered body and WC. Since the contraction rate and the coefficient of thermal expansion of the supporting member made of the base cemented carbide are greatly different, residual stress is generated in the thin surface member, and the composite sintered body made of the surface member and the supporting member in which the residual stress is generated is used. For example, when high-speed cutting is performed, thermal shock applied to the cutting edge of the tool causes damage to the cutting edge portion of the surface member, leading to a relatively short life. However, it is considered that the surface member of the composite sintered body of the present invention has an extremely small residual stress and therefore has improved fracture resistance.

The reason why the component composition and the average particle size in the surface member and the supporting member of the composite sintered body of the present invention are limited as described above will be explained.

(1) Surface member (a) cBN The cBN in the surface member usually has a function of ensuring wear resistance and plastic deformation resistance, but when the ratio in the sintered body is less than 10% by volume, its effect is obtained. On the other hand, if it is contained in excess of 50% by volume, the toughness is lowered and defects are likely to occur, which is not preferable. Therefore, the content of cBN is set to 10 to 50% by volume. The more preferable content of cBN is 15 to 45% by volume. If the average particle size of cBN is 4 μm or less, the fracture resistance is insufficient, and the average particle size is 20 μm.
Since the surface roughness of the work material deteriorates above, the value should be 4 to
It was set to 20 μm.

(B) WC, AlN, TiB ₂ and Al ₂ O ₃ All of these components are dispersed as a hard dispersed phase in the Ti-based compound, and have the effect of suppressing the grain growth of the Ti-based compound. But WC: less than 0.1%, Al
N: less than 3% by volume, TiB ₂ : less than 1% by volume, Al
₂ O ₃ : When the content is less than 3% by volume, there is no grain growth suppressing effect of the Ti-based compound, while on the other hand, WC: more than 1% by volume, AlN: more than 7% by volume, TiB ₂ : more than 5% by volume, Al ₂ O _3:10
If it exceeds the capacity%, the sinterability is lowered and the strength is lowered, which is not preferable. Therefore, the dispersion component is W
C: 0.1 to 1% by volume, AlN: 3 to 7% by volume, TiB
_2: 1-5 volume%, Al ₂ O _3: determined in 3-10% by volume. The more preferable range of these components is WC: 0.3.
˜1% by volume, AlN: 4 to 6% by volume, TiB ₂ : 2 to 5
% By volume, Al ₂ O ₃ : 4-9% by volume. The average particle size of these components in the matrix is 0.
It is 5 μm or less (preferably 0.1 to 0.3 μm).

(C) Ti-based Compounds (TiC, TiN, TiCN) These Ti-based compounds act as a binder phase to ensure heat resistance and toughness, but the average particle size of these Ti-based compounds is 1 μm. Below (preferably 0.4-0.8
μm).

(2) Support Member Although a WC-based cemented carbide is usually used for the support member of the composite sintered body, the W of the composite sintered body support member of the present invention is used.
It is preferable that the C-based cemented carbide contains Co: 25 to 45% by volume, and the balance is a WC-based cemented carbide composed of WC and unavoidable impurities. In particular, it contains Co: 30 to 40% by volume, and the balance: A WC-based cemented carbide composed of WC and inevitable impurities is more preferable. This is because if the Co content is less than 25% by volume, the difference from the coefficient of thermal expansion with the surface member becomes too large, causing residual stress in the surface member, which easily causes chipping. On the other hand, if it exceeds 45% by volume. This is because the strength of the supporting member becomes insufficient, which is not preferable.

[0015]

Examples As raw material powders, TiC powder, TiN powder, TiCN powder, TiAl powder, TiAl ₃ powder, Ti ₂ AlN powder, Ti ₄ Al ₂ C having the particle sizes shown in Tables 1 and 2 are used.
₂ powders, WC powders and Al ₂ O ₃ powders are prepared, these raw material powders are filled with cemented carbide balls and acetone in a container lined with cemented carbide, crushed and mixed by a rotary ball mill after covering with a lid. I went. Thereafter, cBN powder having a particle size shown in Tables 1 and 2 was further added so as to have a composition shown in Tables 1 and 2, wet-mixed for 72 hours, and after drying, a diameter of 3 ton / cm ² was applied at a pressure of 3 ton / cm ^2. 20m
m, thickness: 1.5 mm, which was molded by embossing, and the molded body was vacuum-molded at 3 × 10 ^{−4 to} 3 × 10 ⁻³ Torr for 10 minutes.
Pre-sintering is carried out at a predetermined temperature within the range of 00 to 1300 ° C. for 30 to 90 minutes, and then the pre-sintered body has a diameter of 20.
mm, thickness: 2 mm, and charged into an ultra-high pressure generating and sintering apparatus in a state of being joined to a WC-based cemented carbide support member having the composition shown in Tables 1 and 2, and pressure: 5.5 GP
a, temperature: a composite of the present invention composed of a cutting blade member and a supporting member having a component composition shown in Tables 3 to 4 which are sintered by holding at a predetermined temperature within a range of 1200 to 1400 ° C. for 20 to 60 minutes. Sintered bodies 1 to 10 (hereinafter, sintered bodies 1 to 10 of the present invention
Comparative composite sintered bodies 1 to 8 (hereinafter, comparative sintered body 1)
.About.8) and a conventional composite sintered body (hereinafter referred to as a conventional sintered body). The substances constituting the sintered body are identified by X-ray diffraction, the grain sizes are measured by a scanning type and a transmission electron microscope, and the volume ratio of each substance is determined by scanning type. -Measured using a Je electron microscope.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4] These sinters 1 to 10 of the present invention, comparative sinters 1 to 8 and conventional sinters are ground and cut and divided by electric discharge machining, and brazed to a WC-based cemented carbide base metal, Finally, the present invention cutting tools 1 to 10, comparative cutting tools 1 to 8 and conventional cutting tools were produced by polishing to a predetermined size. (The numbers of the cutting tools and the numbers of the composite sintered bodies to be used are respectively Corresponding) Using these cutting tools Work material: SCM415 (HRC63), Cutting speed: 300 m / min. Cut: 0.15 mm Feed: 0.15 mm / rev. Wet cutting under conditions of 30 minutes, flank wear width (m
m) and others, the condition of the cutting edge was measured and observed, and the results are shown in Table 5.

[0020]

[Table 5]

[0021]

From the results shown in Table 5, the cutting tools 1 to 10 made of the sintered body of the present invention show markedly better fracture resistance than the conventional cutting tools made of the conventional sintered body. I understand. Further, the comparative cutting tools 1 to 1 prepared from the comparative sintered body showing the composition and the particle diameter outside the scope of the present invention.
It can be seen that all of 8 show unfavorable characteristics.

As described above, even when a material such as high hardness steel and cast iron is cut at a high speed by the cutting tool produced by using the composite sintered body of the present invention, the occurrence of defects is small as in the conventional case. Therefore, it can be applied to cutting under more severe conditions than before, and the composite sintered body of the present invention has excellent thermal characteristics such as high thermal conductivity of the cubic crystal nitride sintered body and its high wear resistance. Therefore, it is also useful for various heat sinks, wear-resistant tools, jigs, etc., and has excellent industrial effects.

Claims (3)

[Claims] 1. A composite sintered body in which a surface member made of a cubic boron nitride-containing ceramics sintered body and a tungsten carbide-based cemented carbide support member are joined together, wherein the cubic boron nitride-containing ceramics sintered body is used. The constituent composition of the surface member is as follows: cubic boron nitride: 10 to 50% by volume, tungsten carbide: 0.1 to 1% by volume, aluminum nitride: 3 to 7% by volume, titanium boride: 1 to 5% by volume, Aluminum oxide: 3 to 10% by volume, one or two of titanium carbide, nitride and carbonitride
Or more and inevitable impurities: balance, and the constituent composition of the above-mentioned tungsten carbide-based cemented carbide support member is: cobalt: 25 to 45% by volume; tungsten carbide and inevitable impurities: balance. Cubic boron nitride based ultra-high pressure composite ceramics sintered body and cutting tool. 2. The cubic boron nitride according to claim 1, wherein the cubic boron nitride constituting the surface member of the cubic boron nitride-containing ceramics sintered body has an average particle size of 4 to 20 μm. -Based ultra-high pressure composite ceramics sintered body and cutting tool. 3. An average particle diameter of one or more of titanium carbide, nitride, and carbonitride constituting the surface member of the cubic boron nitride-containing ceramics sintered body is 1 μm or less, and Tungsten carbide, aluminum nitride,
The cubic boron nitride ultrahigh pressure composite ceramics sintered body and the cutting tool according to claim 1 or 2, wherein the average particle diameters of titanium boride and aluminum oxide are both 0.5 µm or less.