JPS60184649A - Manufacture of sintered body of high pressure phase boron nitride - Google Patents

Abstract

PURPOSE:To manufacture a sintered body of high pressure phase BN having high strength, superior wear resistance and toughness by converting the material of the surfaces of high pressure phase BN particles into low pressure phase BN by treatment under temp. and pressure conditions under which high pressure phase BN is unstable, mixing the particles with ceramic powder and metallic powder, and sintering the mixture under temp. and pressure conditions under which high pressure phase BN is stable. CONSTITUTION:The material of the surfaces of high pressure phase BN (cubic BN) particles is converted into low pressure phase BN by treatment under temp. and pressure conditions under which high pressure phase BN is unstable, e.g., at about 1,300 deg.C under about 15kb pressure. The particles are then mixed with a binder consisting of ceramic powder and metallic powder, and the mixture is sintered under temp. and pressure conditions under which high pressure phase BN is stable, e.g., at about 1,300 deg.C under about 45kb pressure. The ceramic powder is made of a compound selected among the carbides, nitrides, borides and silicides of the IVa, Va and VIa group metals in the periodic table, a mixture or a mutual solid soln. of such compounds. The metallic powder is made of Al or consists of N and one kind of metal selected among Si, Ni, Co, Fe, Cr and Mn, a mixture or a mutual solid soln. of such metals.

Description

[Detailed Description of the Invention] (a) Technical Field This invention is a high-pressure phase nitriding process that is suitable for use in cutting, etc., and has excellent strength, wear resistance, and toughness.
The present invention relates to a method for manufacturing a sintered cord II.

(b) Technical background High-pressure phase type nitridation (111 element includes cubic crystal nitride element (hereinafter referred to as CBN) and wurtzite type boron nitride (hereinafter referred to as WB).
There are two types of diamonds, both of which have the highest hardness next to diamond, and are less reactive with iron group metals than diamonds, so they are extremely promising as materials for grinding and cutting tools. Yes, it is already widely used.

Particularly for cutting applications, sintered bodies made of CBN bonded with Go or the like are partially used.

As mentioned above, CBN is a material that has high hardness and excellent heat resistance and wear resistance. There have been various attempts to sinter only this CBN, for example,
As described in Japanese Patent No. 8948, it is necessary to sinter the material at a size of about 70 kb or more and at an extremely high pressure and high temperature of 1900° C. or more.

Current ultra-high-pressure, high-temperature equipment can generate such high-pressure and high-temperature conditions, but if the equipment is enlarged to a collective scale, the number of times the high-pressure and high-temperature generating section can be used is limited, making it impractical.

Further, as mentioned above, some sintered bodies are used in which metals such as porcelain are bonded together, but when this is used as a cutting tool, (1) wear progresses from the metal bonding phase.

(2) The presence of the metal phase reduces the welding resistance of the entire sintered body.

+31 CBN with low bond strength due to high GBN content
There is a lot of contact between the particles, and there is often destruction between the CBN particles.

A problem arises. This is due to the metallic phase due to the following factors.

General ↓ When forming a whole CBN sintered body, first apply pressure (and then raise the temperature. Then, if the temperature is sufficiently high, the molten metal will penetrate into the gaps between the CBN particles.

Therefore, when pressure is applied and a catch occurs between the CBN particles and a so-called crosslinking phenomenon occurs, this gap becomes narrow and a large metal phase is formed in this part. This large metal phase causes a welding phenomenon and deteriorates the performance of the entire sintered body as described above.

(C) Disclosure of the Invention This invention reduces the occurrence of large metal phase segregation as described above, further reduces the gap between particles of high-pressure phase type boron nitride, and reduces the amount of metal contained. The aim is to increase the bonding strength between high-pressure phase type boron nitride particles.

The following two methods can be considered to prevent crosslinking from occurring.

One is to do this in the absence of a binder, and the other is to do so in the presence of a molten metal in the binder.

The former converts the surface of high-pressure phase boron nitride particles into low-pressure phase boron nitride (hereinafter referred to as hBN), and hB is generated on this surface.
The idea is to eliminate the occurrence of crosslinking by utilizing the low strength and lubricity of N.

A method of converting the surface of high-pressure phase type boron nitride particles into IIBN under normal pressure or reduced pressure in advance, and drawings abcd during sintering.
As shown in e〆1, there is a method of exposing the high-pressure phase type boron nitride to an unstable region and converting the surface to hBN. In the latter method, the metal in the binder is melted under high pressure in the unstable region of the high coarse phase type 11N+ element during sintering, for example as shown in drawing aMe, and then the metal in the binder is melted under high pressure in the unstable region of the high coarse phase type boron nitride. This method reduces cross-linking between particles by dissolving some of the high-pressure phase type boron nitride particles into the metal, or by converting them into hBN.

High-pressure phase type boron nitride particles are highly compressed.If conditions are selected, the latter method has the possibility of obtaining a sintered body with a smaller amount of metal.

In any case, the final step of sintering is high-pressure phase type nitrided riJI
Since the process is carried out in the stable region of the element, the portion converted to hBN returns to high-pressure phase type boron nitride.

No. 4a of the periodic table used as a bonding phase in this invention,
5a, 6aIJ' include metal carbides, nitrides, and compounds, ■
``One type of compound bt, < is a mixture or mutual solid solution of these compounds, and Relamic J5) is +llI! + Sadness is high, J't+ A11l! In addition, these Relamic materials have metallic properties compared to oxides. In particular, the thermal conductivity of these Relamic materials is similar to that of metal.

By using the above-mentioned relamic material containing J and Unakoma tiI as a binding phase, the above-mentioned CI3N single-grain IC can be obtained.
! It is possible to obtain a sintered body that is superior to l:J19.

M) By forming the above Roramic material into the binder phase, the amount of metal in the binder phase is relatively reduced.

+Nk IEi-, phase! -゛2Nitride 11j+ A high bonding strength between elementary particles can be obtained if there is a phenomenon of dissolution and reprecipitation of hard particles into the bonding metal, such as in liquid phase sintering of wc-co cemented carbide.

Next, in this invention, the bonded phase (A & or N and 5j1Nj, used, one type of Fe, Cr, Kn, or a mixture or mutual solid solution of CB
It is a catalyst during N synthesis, and the melt and surface of these metals are converted to hBN during sintering. Since the I elementary particles are in contact, IC
This phenomenon occurs, and the bonding between the high-pressure phase type boron nitride particles is enhanced.

That is, since the final culm of sintering is carried out in the stable region of high-pressure phase type boron nitride, it is considered that hBN is dissolved and high-pressure phase type boron nitride is precipitated. In addition, since the high-pressure phase boron nitride particles are compressed at this time, the precipitated high-pressure phase boron nitride grows the contact areas between the particles, increasing the bonding strength between the high-pressure phase boron nitride particles and β- It will be done.

In this invention, the apparatus used to obtain the sintered body is a belt-type, girdle-type, ultra-high-speed apparatus used for die synthesis.

The temperature and pressure conditions for sintering are shown in the drawing.
J high JJg 4Ll halinitride Ill It is carried out in the stable region of the formation. In this area, above 1200℃C pressure 40k
b or more is preferable.

The detailed description of the invention by Riko J is given in the Examples above.

Example 1 CB'NI) end binder powder having an average particle size of 2 μm was mixed with the composition shown in Table 1, and then sintered using an ultra-high pressure and high temperature apparatus used for diamond synthesis.

First, the pressure was raised to 15 kb, and then heated to a temperature of 1300°C and held for 5 minutes.

The mouth region is a CBN unstable region. After this, increase the temperature to 130
After keeping it at 0'C, the pressure was slowly increased to 45 kb for 10 minutes, then the temperature was lowered and the pressure was lowered further.

In the sintered body, the binder phase was uniformly distributed in structure, and there was not much 118N remaining.

Without adopting the method of this invention, the pressure was first increased to 45 kb.
and then raise the temperature to 1300℃ while maintaining the pressure.
The sintered body obtained by holding for 10 minutes showed segregation of metal and was not completely sintered.

Table 1 Example 2 CBN powder with an average particle size of 4μ was prepared in advance into 10 mm 1-11
The surface of the CBN particles was converted to hBN by holding at 1300° C. for 10 minutes under vacuum.

This powder was used instead of the CBN powder used in Example 1,
The binders shown in Table 1 were mixed to the same composition, then filled into a container and sintered using an ultra-high pressure and high temperature apparatus used for diamond synthesis.

First, the pressure saw was raised to 45 kb, and the temperature was raised to 1300°C and held for 15 minutes.

The structure of the obtained sintered body was almost the same as that of the sample obtained in Example 1.

Example 3 CBN powder with an average quarantine of 3 μm and binder powder were mixed to have the composition shown in Table 2, and then filled into a container.

These were sintered in the same manner as in Example 1 to obtain a sintered body.

Using this sintered body and a sintered body made of commercially available ω etc. as a binder, the FCD45 was set at a circumferential speed of 300+n/Ill! II,
Penetration 0, 3 nun, feed Q, 1mm/IeV
, Cutting was carried out under the conditions of the tki1 formula. The results were as shown in Table 2.

In addition, the average voltage detection for ceramic materials and metals is 1 μ and 40 μ, respectively.
A saw using wood.

Table 2 Example 4 A binder having the same composition as Sample No. 005 of Example 3 and high-pressure phase boron nitride having the composition shown in Table 3 were mixed and filled into a container.

This container was sintered using the same equipment as in Example 1.

3° Table J, J” f: L force to 20 k b -1 glc, 1
Heat to 300℃ and hold for 10 minutes. -After increasing the j1 force to 45kb, further)mu, 11
After holding the temperature at 1400°C for 15 minutes, the temperature decreases and the temperature decreases.

These sintered bodies are the sintered bodies of sample N095 of Example 3.
, and CIC2 using a commercially available sintered body with Co'c as a binder. i to Ir1l j%! +OOm / 1l
lin, depth of cut 0°4mm, feed 0.2mm' r
(!V, dry strip ('I') was cut. The result was 'C' as shown in Table 4 of [1].

Table 4

[Brief explanation of the drawing]

The drawing is for explaining the production line 1'1 of a sintered body by the method of the present invention, and shows the thermodynamic stable region of a3 on the pressure-temperature phase diagram of high-pressure phase type boron nitride. It is. 1...Cubic crystal - low pressure phase type boron nitride equilibrium line A...High pressure phase type boron nitride stability region B...Low pressure phase type boron nitride stability region Special price ¥1 Applicant Sumitomo Electric Industries, Ltd. Agent Ben 1) Akira

Claims (1)

[Claims] (1) The surface of high-pressure phase boron nitride is converted into low-pressure phase boron nitride within an unstable temperature and pressure range from high-pressure phase boron nitride particles, ceramic powder, and metal powder. A method for producing a high-pressure phase type boron nitride sintered body, which comprises mixing the high-pressure phase type boron nitride with a binder, and then sintering the high-pressure phase type boron nitride within a stable humidity and pressure range. (2) The method for producing a high-pressure phase type boron nitride sintered body according to claim 1, wherein the high-pressure phase type Ia nitride is cubic boron nitride. , f4311? As a binder made of lamic powder, carbides and nitrides of metals listed in Periodic Table 4a, 5a, 6al/*
Claim 1 characterized in that one of borides and silicides, a mixture thereof, or a mutual solid solution is used.
8. A method for producing a positive phase boron nitride sintered body as described in Section 8. (4) N or N and Si as a binder made of metal powder
, Ni, Fe, Cr, Mn, or a mixture or (, 1 mutual solid solution) is used. Method. (5) After mixing high-pressure phase type boron nitride particles with a binder consisting of Leramigge powder and metal powder, the high-pressure phase type boron nitride is unstablely quenched, and once held under high pressure within a pressure range,
Production of a high-pressure phase boron nitride sintered body, which is characterized by avoiding contact between the molten metal in the binder and high-pressure phase boron nitride particles, and then sintering within the stable temperature and pressure range of the high-pressure phase boron nitride. Method. (6) The method for producing a high-pressure phase boron nitride sintered body according to claim 5, wherein the high-pressure phase boron nitride is cubic boron nitride. (7) As a binder made of ceramic powder, one of carbides, nitrides, borides, and silicides of metals in groups 4a, 5a, and 6a of the periodic table, or a mixture or mutual solid solution thereof is used. Claim No. 51jJ
The method for manufacturing the high-pressure phase type boron nitride sintered body described above. (8) Binding material made of metal powder is N or N and Sl
, N1, ω, Fe, Cr, in, a mixture thereof, or a mutual solid solution. 56. A method for producing a high-pressure phase type III nitride sintered body according to claim 55.