JPH08260129A - Cubic boron nitride composite cermet tool and its production - Google Patents

Abstract

PURPOSE: To produce a CBN composite cermet tool high in hardness, having a long service life and furthermore excellent in cuttability by mixing CBN particles stuck with the fine particles of TiN, Ni or the like and a base material made of Ti, N, and Ni, etc., under specified conditions and executing sintering. CONSTITUTION: The fine particles of one or more kinds selected from among TiN, TiC, Ni and Co are physically stuck to the particles of cubic boron nitride (CBN) (having about 0.5 to 5μm average particle size) by plasma coating. This CBN particles, 1 to 60vol.%, and the balance base material (having <=2μm average particle size) composed of one or more kinds among TiN, TiC, TiCN, NbC, WC and Mo2 C and one or more kinds of Ni and Co are mixed. Next, this mixture is sintered by HIP at <=1600 deg.C under <=2000 atmospheric pressure in an inert gas. Thus, the cubic boron nitride composite cermet tool excellent in strength and wear resistance can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cubic boron nitride composite cermet tool and its manufacturing method. INDUSTRIAL APPLICABILITY The tool of the present invention can be suitably used for cutting of ordinary cast iron, ductile cast iron, high hardness materials and heat resistant alloys.

[0002]

2. Description of the Related Art Cubic boron nitride (hereinafter referred to as "CBN") has the second highest hardness after diamond, high thermal conductivity and high electrical insulation, and has an affinity with iron group metals. It is used as a tool material for cutting or grinding high hardness materials such as hardened steel and heat resistant alloys such as nickel-based alloys and cobalt-based alloys because they have little reaction with ferrous metals unlike high diamonds.

Conventionally, as a method of manufacturing a tool material of this type, since CBN is a brittle material and is a material that is difficult to sinter, a method of coating CBN with metal (Al) and sintering it at an ultrahigh pressure (special (Kaihei 3-205364), a method in which CBN is coated with carbonitride oxide, and ultra-high pressure sintering (Japanese Patent Laid-Open No. 5-51267), and CBN is made of metal (V, Nb, T)
a, W, Cr) nitride or boride is coated, and this is mixed with a binder phase forming substance such as a carbide, nitride, or oxide of a 4a, 5a, or 6a group metal, and hot isostatic pressure (HIP) is applied. Alternatively, a method of forming by hot pressing (HP) (Japanese Patent Laid-Open No. 5-163071), CBN is coated with a first layer of a Ti compound and a second layer of an Al compound, and one of Ti compound and Al compound is coated. A method of mixing with one or more kinds of binder phase forming substances and performing ultra-high pressure sintering (JP-A-5-31
No. 0474), a method has been adopted in which CBN is coated and then pressure-sintered.

[0004]

In any of the above-mentioned conventional manufacturing methods, the means for coating the CBN with another substance is the chemical vapor deposition (CVD) method. Therefore, the coating material is vapor-deposited so that the film formation rate is slow, and the film nuclei are preferentially formed on the corners and rough surfaces of the CBN particles, so that peeling may occur after coating or the film properties may be deteriorated. Becomes uneven. As a result, CBN after coating
The tool obtained by sintering the particles was inferior in strength and wear resistance.

The inventor has tried various experiments on how to form a homogeneous coating or particle enclosure on the CBN. As a result, if the CBN particles are not covered with a layer having a certain thickness but the particles are physically attached using a certain method, it is possible to uniformly coat the particles and the sinterability and the characteristics are significantly improved. understood. Therefore, an object of the present invention is to provide a tool material excellent in strength and wear resistance from CBN particles uniformly covered with another substance.

[0006]

In order to achieve the above object, the cubic boron nitride composite cermet tool of the present invention is one kind selected from nitrides, carbides and carbonitrides of 4a, 5a and 6a group metals. 1 to 60 vol% of cubic boron nitride particles as a hard dispersed phase covered with one or more layers selected from the above fine particles and / or iron group metals
And at least one selected from the group consisting of nitrides, carbides, and carbonitrides of 4a, 5a, and 6a metals as the balance base material, and at least one selected from iron group metals.

The fine particles or layer components include, for example, Ti.
Any one or more of N, TiC, Ni and Co may be mentioned. As the base material, TiN, TiC, TiCN, Nb
At least one selected from C, WC and Mo ₂ C and Ni
And a combination of one or more of Co. Among the above, particularly, the cubic boron nitride particles have an average particle size of 0.5 μm or more and 5 μm or less, and the base material has an average particle size of 2 μm.
It is desirable that the thickness is μm or less.

A suitable method of making the cubic boron nitride composite cermet tool of the present invention is characterized by the following steps. (A) A step of physically adhering to the cubic boron nitride particles one or more kinds of fine particles selected from nitrides, carbides, carbonitrides and iron group metals of 4a, 5a and 6a group metals. (B) 1 to 3 of cubic boron nitride particles to which the above fine particles are fixed
A step of mixing 60 vol% with the balance of one or more selected from nitrides, carbides and carbonitrides of 4a, 5a and 6a metals and one or more selected from iron group metals. (C) A step of sintering the mixture.

Here, as a means for physically fixing, for example, plasma coating. The equipment for that is
For example, it comprises a cylindrical plasma torch, a quartz double tube connected to its lower end, a cooling double tube connected to its lower end, and a chamber connected to the lowermost part. In the plasma torch, a quartz tube is arranged inside and a cooling tube is arranged outside, a high frequency oscillation coil is arranged in the middle, a gas ejection port is provided above, and a fine particle raw material supply port is provided on a side surface. The supply port for the particles to be coated (CBN particles in the present invention) is provided on the side surface of the cooling pipe. Then, a necessary gas such as argon, nitrogen, or oxygen is ejected from the gas ejection port, a plasma flame is formed inside the quartz tube of the plasma torch by a high frequency power source, and a metal powder or a metal compound powder to be fine particles is argon there. Is introduced together with a carrier gas such as, and the powder is dropped toward the cooling pipe in a plasma state. Then, when CBN particles are introduced together with a carrier gas such as argon from the side surface of the cooling pipe, predetermined fine particles are uniformly adhered to the surface of the CBN particles.

Sintering is usually carried out by HIP or normal sintering. In the case of HIP, the sintering conditions are: inert gas pressure 2
It is desirable that the pressure is 000 atm or less and the temperature is 1600 ° C. or less. In the case of normal sintering, the sintering conditions are:
It is preferably 600 ° C or lower.

[0011]

According to the above manufacturing method, fine particles (for example, Ti
N) a raw material powder (Ti powder or TiN powder) and a gas (N ₂ and Ar) are supplied into the thermal plasma to produce a desired coating material as fine particles by a chemical reaction, and CBN is formed before the fine particles aggregate. Supply particles. as a result,
The particles are physically strongly adhered to the CBN particles.
It does not peel even in the mechanical mixing process when the N particles and the binder phase forming substance (base material) are combined.

When the substance to be fine particles is a carbide, a nitride or a carbonitride, it does not cause a chemical reaction with the base material forming component itself, but has good wettability with the base material forming component. Improves sinterability and improves cutting performance such as wear resistance and fracture resistance as a cutting tool. In this case, the fine particles adhered to the CBN particles remain as fine particles even after sintering (Type 1). When the fine particles are an iron group metal, they react with the iron group metal in the base material during the sintering process to form a layer that almost uniformly covers the CBN particles (Type 2).

However, if the content of CBN particles is less than 1%, improvement in hardness and strength as a hard dispersed phase cannot be expected, and if it exceeds 60%, the inexpensive HIP method or ordinary sintering method is used. Since it is difficult to densify, the content should be 1-60%.
Limited to. A particularly desirable content range is 15-40
%.

[0014]

【Example】

[Fixation of fine particles] First, a means for fixing fine particles to CBN will be described. A raw material in a predetermined ratio is introduced together with a carrier gas into a plasma torch in which a plasma flame has been formed, and high frequency heating is performed to synthesize active particles in a plasma state. At that stage, the fine particles are present as a gas flow in the inert gas. CBN particles are introduced there to physically fix the fine particles on the surface of the CBN particles. Specific raw materials and carrier gas are as follows.

When fixing TiN fine particles: Ti fine powder, N ₂ gas, Ar gas or TiN fine powder, Ar gas When fixing TiC fine particles: Ti fine powder, CO ₂ gas, CH ₄ gas, Ar gas or TiC Fine powder, Ar gas When fixing Co fine particles: Co fine powder, Ar gas When fixing Ni fine particles: Ni fine powder, Ar gas

[Manufacture of Sintered Body and Tool] Next, commercially available CBN particles having various particle diameters were subjected to the above-mentioned method to obtain an average particle diameter of 0.0
5 μm TiN, 0.03 μm Co or 0.03 μm
A method of adhering fine particles of Ni having a diameter of μm and using the raw material as a raw material to manufacture a sintered body and a tool will be described. Raw materials other than CBN are titanium nitride Ti having an average particle size of 1.0 μm.
N, titanium carbide TiC having an average particle diameter of 1.5 μm, niobium carbide NbC having an average particle diameter of 1.5 μm, tungsten carbide WC having an average particle diameter of 1.0 μm, molybdenum carbide Mo ₂ C having an average particle diameter of 1.0 μm, average particles Nickel Ni with a diameter of 0.5 μm,
Cobalt Co having an average particle size of 0.5 μm.

CBN particles to which fine particles were fixed and other raw material powders were weighed in a predetermined composition shown in Table 1, put into a resin pot with a mixed solvent of ethanol and acetone, and ball-milled and mixed. The mixture was dried under reduced pressure, added with wax, and then granulated with a spray dryer. The granulated powder is pressure-molded into a predetermined shape, degreased, and then normally sintered as it is, or vacuum-encapsulated in a glass capsule to a pressure of 2000.
HIP sintering at atmospheric pressure.

The obtained sintered body was subjected to ISO standard SNGN12.
The tool shape of 0408 was polished, and the desktop performance such as micropore and hardness and the cutting performance based on Test 1 and Test 2 were evaluated. The micropores are observed with a scanning electron microscope, and are represented by AN (the grade of pores according to ASTM standard B276-79. N: integer value).

[Test 1] Carbon steel S with slits
Cutting speed V = 200m for the outer diameter of the cylinder made of CM415
/ Min. , Feed f = 0.1 mm / rev, cut d
= 0.5 mm, dry continuous cutting was performed, and the time until chipping or chipping occurred on the cutting edge was measured.

[Test 2] SNCM8 (HB300-3
Cutting speed V = 500 m / mi
n. , Feed f = 0.4 mm / rev, cut d = 0.
Dry continuous cutting was performed at 5 mm, and the VB wear amount of the cutting edge was measured.

The above results are shown in Table 1. In the remarks column, Type 1 and Type 2 indicate a form in which the former fine particles adhered to the CBN surface exist as fine particle crystals even after sintering, and the latter exist as a layer by reacting with the base material forming components and impurities.

Although only the composition is shown in the table, the metal components, oxygen, nitrogen, etc. contained in the obtained sintered body are
Carbon was quantitatively analyzed by EPMA. Regarding the amount of CBN, the volume ratio was measured by observing the structure with SEM and simultaneously performing image processing. From the above quantitative analysis results, it was confirmed that the composition of the sintered body in Table 1 was almost the same as the composition of the composition.

[0023]

[Table 1] Sample No. 1 to 9 belong to the scope of the present invention,
Both desktop performance and cutting performance were excellent. On the other hand, the sample No. No. 10 had a low hardness because it did not become densified because CBN was excessive. Therefore, test 1
In test 2, chipping occurred.
In addition, No. In No. 11, since CBN particles to which fine particles were not fixed were used as a raw material, hardness was also low and cutting performance was inferior. No. No. 12 did not contain CBN and therefore had a low hardness and probably a low strength, so that in Test 2 it plastically deformed during cutting.

[0024]

As described above, the tool of the present invention has a high hardness, a long life, and excellent cutting performance. Further, according to the manufacturing method of the present invention, sinterability can be improved.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C04B 35/583 C04B 35/56 M C22C 1/05 35/58 103H

Claims (8)

[Claims] 1. At least one kind of fine particles selected from nitrides, carbides and carbonitrides of 4a, 5a and 6a group metals and / or
Or cubic boron nitride particles 1-60 as a hard dispersed phase covered with one or more layers selected from iron group metals
and a balance of at least one selected from the group consisting of nitrides, carbides and carbonitrides of 4a, 5a and 6a metals as a base metal, and at least one selected from iron group metals. Boron nitride composite cermet tool. 2. A fine particle or a layer component is TiN or Ti.
The cubic boron nitride composite cermet tool according to claim 1, which is one or more of C, Ni and Co. 3. The base material is TiN, TiC, TiCN, N
at least one selected from bC, WC and Mo ₂ C and N
The cubic boron nitride composite cermet tool according to claim 1, which is one or more of i and Co. 4. The cubic boron nitride particles have an average particle size of 0.
The cubic boron nitride composite cermet tool according to claim 1, wherein the base material has an average particle diameter of 5 μm or more and 5 μm or less and 2 μm or less. 5. A method for producing a cubic boron nitride composite cermet tool, which comprises the following steps. (A) A step of physically adhering to the cubic boron nitride particles one or more kinds of fine particles selected from nitrides, carbides, carbonitrides and iron group metals of 4a, 5a and 6a group metals. (B) 1 to 3 of cubic boron nitride particles to which the above fine particles are fixed
A step of mixing 60 vol% with the balance of one or more selected from nitrides, carbides and carbonitrides of 4a, 5a and 6a metals and one or more selected from iron group metals. (C) A step of sintering the mixture. 6. The method for producing a cubic boron nitride composite cermet tool according to claim 5, wherein the physically fixing means is plasma coating. 7. The sintering condition is an inert gas pressure of 2000.
6. The HIP having an atmospheric pressure or lower and a temperature of 1600 ° C. or lower.
A method for manufacturing the cubic boron nitride composite cermet tool according to 1. 8. The method for producing a cubic boron nitride composite cermet tool according to claim 5, wherein the sintering conditions are normal sintering under a normal pressure of an inert gas and a temperature of 1600 ° C. or less.