JPS6053721B2 - Composite sintered parts for cutting tools - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention can be used as a cutting tool for cutting high hardness steel, which requires high hardness, and excellent wear resistance, toughness, and corrosion resistance, as well as Ni-based or Co-based super alloys. The present invention relates to a composite sintered member suitable for use and a method for manufacturing the same.

In recent years, it has been proposed to use cubic boron nitride sintered materials and cubic boron nitride-based sintered materials containing small amounts of Al and iron group metals for cutting the various materials listed above. However, the former sintered material has excellent wear resistance but lacks toughness, and the latter sintered material has poor wear resistance especially when used under conditions with high heat generation. At present, none of these materials have satisfactory properties. Therefore, in order to impart toughness to the cubic boron nitride sintered material and the cubic boron nitride-based sintered material (hereinafter collectively referred to as cubic boron nitride-based sintered material), we developed a carbonized material with excellent toughness. A composite sintered member has been proposed in which the cubic boron nitride-based sintered material (hereinafter referred to as C-BN-based sintered material) is combined with a tungsten (hereinafter referred to as WC)-based cemented carbide sintered base material. The composite sintered member has excellent wear resistance due to the C-BN based sintered material and excellent toughness due to the WC based cemented carbide sintered material. It is attracting attention as an indicator of cutting performance.

However, the above-mentioned composite sintered members have problems such as cracks easily occurring at the joint interface during use, and in extreme cases, even delamination, making it difficult to use them stably over a long period of time. It was hot.

From the above-mentioned viewpoints, the present inventors conducted research to solve the problems of the conventional composite sintered members and to obtain a composite sintered member that can be used stably over a long period of time. As a result, (a) the reason why the bonding strength of the conventional composite sintered member is inferior is that, although it is not clear, there is a region with a high CO concentration (hereinafter referred to as a CO-enriched layer) at the bonding interface. Something that is considered to be true.

(b) One of the reasons why the bonding strength deteriorates when a CO-enriched layer exists at the bonding interface is that C-
Young's modulus of BN-based sintered material is 7 x 10-4 kg/D, W
The Young's modulus of a C-based cemented carbide sintered base material, for example, a WC-6 wt% CO sintered base material, is 6.4×101k9/Wlt, whereas that of CO is 2.2×10ik9/Wlt. If there is a large difference in the elastic modulus, stress concentration may occur especially at the interface between the C-BN-based sintered material and the CO-enriched layer due to repeated loads when used as a cutting tool. It is thought that this stress concentration causes the joint strength to deteriorate.

(c) Similarly, the presence of a CO-enriched layer is another reason why the bonding strength deteriorates.
The linear expansion coefficient of the base sintered material is 3.5 x 10-6/°C, for example, the linear expansion coefficient of the WC-6 wt% CO sintered base material is 5 x 1
0-6/℃, while that of CO is 12×10
-6/°C, and if there is such a large difference in thermal expansion coefficient, C. It is believed that stress concentration occurs at the interface between the BN-based sintered material and the CO-enriched layer, and that this stress concentration causes the bonding strength to deteriorate.

As a result of obtaining the certified fabrics shown in items (a) to (c) above and further conducting research based on these certified fabrics, (d) WC
When manufacturing a composite sintered member in which a C-BN-based sintered material is bonded to a base superalloy sintered base material, in order to effectively carry out the coating treatment and sintering, the base material is already sintered and formed. attitude. A WC-based cemented carbide is used, and one of the group consisting of titanium carbide, nitride, and boride, and a composite compound of two or more of these is used on the bonding surface of this base material.
After forming an intermediate layer consisting of a species or two or more species by a conventional physical vapor deposition method, chemical vapor deposition method, electrophoresis method, etc., a C-BN group mixed powder or compacted powder is applied via the intermediate layer. By arranging the bodies adjacent to each other and then sintering them as a whole under high temperature and high pressure, there is no generation of a CO-enriched layer at the joint interface, and the components constituting the intermediate layer and the WC-based cemented carbide sintered base material The WC component and the C-BN component in the C-BN-based sintered material diffuse well into each other under high temperature and high pressure, so that a strong bonding interface is ensured.

(e) In the intermediate layer, the carbide concentration near the interface with the WC-based cemented carbide sintered base material, and the nitride and boride concentrations near the interface with the C-BN-based sintered material, respectively. When the temperature is relatively high, interdiffusion between the intermediate layer and both sintered materials is promoted, resulting in dramatically improved bonding strength. The findings shown in sections (d) and (e) above were obtained.

Therefore, the present invention was made based on the above findings, and the surface of the WC-based cemented carbide sintered base material is coated with titanium carbides, nitrides, and borides, or two or more of these. one or two of the group consisting of complex compounds of
After coating with an intermediate layer having a thickness of 0.001 to 0.05 mm or more, a C-BN based mixed powder or a green compact thereof is placed adjacently through the intermediate layer, and then the whole is coated with
By heating and holding at a temperature of 1200° C. or higher under high pressure of 40 Kb or higher and sintering, the WC-based cemented carbide sintered base material is coated with the intermediate layer having a layer thickness of 0.001 to 0.05 wn. The present invention is characterized in that a composite sintered member is manufactured by combining C-BN-based sintered materials.

In addition, in this invention, the layer thickness of the above-mentioned intermediate layer is 0.00
The reason why the layer thickness was limited to 1 to 0.05 m was because a layer thickness of less than 0.001 m would not ensure the desired excellent bonding strength, whereas 0.05 T! r! ! This is based on the reason that if the layer thickness exceeds L, the brittleness of the intermediate layer itself will affect the entire member, resulting in a decrease in the toughness of the member.

In addition, the sintering pressure is 40Kb or more, and the sintering temperature is 1200℃.
The above is because at pressures and temperatures below these lower limits, the components constituting the intermediate layer, the WC component, and the C-BN
The mutual diffusion of components is insufficient, making it impossible to obtain the desired strong bonding interface, and furthermore, pressure and temperature higher than the above lower limit values are required for complete sintering of the C/BN-based mixed powder or green compact. This is for the reason.

Next, the present invention will be explained with reference to examples.

Example 1 JIS-KlO(7) WC-based cemented carbide was prepared as a sintering base material, and this base material was charged into a chemical vapor deposition reactor.
While heating and maintaining the temperature in the reactor at 1000°C, TiCl4: 200cc/Min, CH4:
100cc/6min, N2: 30cc/Min, H2
:9670cc/Min ratio (total gas flow rate 10e/M
In), the bonding surface 1 of the base material is heated to RlCO. 7NO
．． An intermediate layer of titanium carbonitride having a composition of 3 and a thickness of 0.005 mm was coated.

Next, the WC-based cemented carbide sintered base material covered with the intermediate layer is Z
After charging into a cylindrical thin-walled container made of R, on the intermediate layer,
Average particle size 0.005μm (7) C-BN powder: 8% weight
and tantalum nitride (TaN) powder with the same 2 μm diameter: 60 mg of C-BN based mixed powder consisting of 2% by weight was charged, and then the whole was charged into a normal ultra-high pressure and ultra-high temperature generator, and the pressure was increased. By holding and sintering the three powders at 50Kb1 temperature: 1300°C, the thickness of each powder becomes WC.
Base cemented carbide base material: 1Tfr! N, middle layer: 0.005T
A composite sintered member of the present invention (hereinafter referred to as the composite member 1 of the present invention) consisting of 0.8 pieces of sn, C/BN-based sintered material was produced.

In addition, the ratio of the reaction gas was TiCl4:400cc/Mi
n, CH4: 60cc/Min, N2: 60cc/Mi
n, H2: 9480cc/Min, reaction temperature 11
TiCO
・、NO. The conditions were the same as in the above example except that an intermediate layer having a composition of .
W! A composite sintered member of the present invention (hereinafter referred to as the composite member of the present invention 2) consisting of I, C/BN-based sintered base material: 0.8Tf0n was produced.

Further, an intermediate layer made of titanium nitride (TiN) was formed at a substrate temperature of 500°C and a N2 atmosphere pressure of 1×10-2 t0r.
r, load voltage: 1 K■, reaction time: 10 rnin, except that it was formed by the ion blating method, under the same conditions as the manufacturing conditions of the composite member 1 of the present invention, and the thickness of each was changed to WC-based carbide. Alloy base material: 1 ugly, intermediate layer: 0.0
3Twt1c●BN-based sintered material: A composite sintered member of the present invention (hereinafter referred to as the composite member 3 of the present invention) consisting of 0.8 pieces was manufactured. For the purpose of comparison, a comparative composite sintered member (hereinafter referred to as comparative composite member 1) was manufactured under the same manufacturing conditions as the composite member 1 of the present invention, except that no intermediate layer was formed.

Furthermore, for comparison purposes, the layer thickness of the intermediate layer was adjusted to 0.0008Tn and 0.07Tn, respectively, by adjusting the reaction retention time. Comparative composite members 2 and 3 were manufactured under the same manufacturing conditions as the above-described composite member 1 of the present invention and composite member 2 of the present invention, except for the following. Next, cutting blades were cut out from the resulting composite members 1 to 3 of the present invention and comparative composite members 1 to 3, and the cutting blades were soldered to a WC-based cemented carbide tip using silver solder. By attaching the cutting tools 1 to 3 of the present invention and comparative cutting tools 1 to 3,
3 were produced respectively.

Regarding the above-mentioned cutting tools 1 to 3 of the present invention and comparison cutting tools 1 to 3, workpiece material: carburized and hardened steel (hardness RO: 60) cutting speed: 100 m/Min feed rate 0.10 m/Rev. A cutting test was conducted under the conditions of , depth of cut: 1.2 mm, and the time required for flank wear to reach 0.21 m was measured, and the tool life was determined.

The measurement results are shown in Table 1. As shown in Table 1, cutting tools 1 to 3 of the present invention using composite members 1 to 3 of the present invention each having an intermediate layer thickness within the range of the present invention, all have an extremely long tool life. In contrast to showing
Comparative cutting tool 1 using comparative composite member 1 without the formation of an intermediate layer showed only about 25 to 40% of the tool life of the cutting tool of the present invention, and the comparative cutting tool 1 in which the layer thickness of the intermediate layer was outside the scope of the present invention. It is clear that Comparative Cutting Tools 2 and 3 (using Composite Members 2 and 3, respectively) exhibit longer tool life than Comparative Cutting Tool 1, but do not exhibit satisfactory tool life.

Example 2 A JIS-KlO WC-based cemented carbide was prepared as a sintering base material, and this base material was charged into a chemical vapor deposition reactor, and the temperature inside the reactor was heated and maintained at 950°C, and the TiCl4: 10cc/Min, BCl3: 20c in the reactor
c/Min, Ar'2: By keeping the reaction gas flowing at a ratio of 1970 cc/Nlln (total gas flow rate 2e/Min) for 1 hour, the bonding surface of the base material has a composition of TiB2. layer thickness 10μm (0.017m
) was coated with an intermediate layer made of titanium boride.

Next, the WC-based cemented carbide sintered base material covered with the intermediate layer is Z
After charging into a cylindrical thin-walled container made of R, on the intermediate layer,
C-BN powder with average particle size 0.5 μm: 97% by volume
and 100 m9 of a C-BN based mixed powder consisting of 3% by volume of Ti powder with a particle size of 275 mesh or less, and then the whole was charged into a normal ultra-high pressure and ultra-high temperature generator, and the pressure was 50 Kb1. : By holding and sintering the three powders at 1300℃, the thickness of each powder becomes WC.
Base cemented carbide sintered base material: 1707! , Middle layer: 0.01T
fr! ! I, C-BN based sintered material: 0.6TIrI1L
A composite member 4 of the present invention consisting of the following was manufactured.

Moreover, for the purpose of comparison, a comparative composite member 4 was manufactured under the same manufacturing conditions as the composite member 4 of the present invention, except that no intermediate layer was formed.

Next, the cutting tool 4 of the present invention and the comparative cutting tool 4 were manufactured from the composite member 4 of the present invention and the comparative composite member 4 under the same conditions as in Example 1, and the following conditions were used: Work material: Hasteiro × Cutting speed: 70n1/Minl Feed 0.1WR/Rev. A cutting test was conducted under the conditions of , depth of cut: 0.5Tn1, and the cutting time until flank wear reached 0.1 m was measured, and the tool life was determined.

As a result, the comparative cutting tool 4 using the comparative composite member 4'' without the formation of an intermediate layer reached the end of its life after 6 pieces.
The cutting tool 4 of the present invention using the composite member 4 of the present invention exhibited twice the tool life.

Claims (1)

[Scope of Claims] 1. One or two of the group consisting of titanium carbides, nitrides, and borides, and composite compounds of two or more of these, on a tungsten carbide-based cemented carbide sintered base material. A composite sintered member for a cutting tool, which is made of a cubic boron nitride-based sintered material via an intermediate layer having a thickness of 0.001 to 0.05 mm. 2. The surface of the tungsten carbide-based cemented carbide sintered base material is coated with one or two of the group consisting of titanium carbides, nitrides, and borides, and composite compounds of two or more of these.
After coating with an intermediate layer having a layer thickness of 0.001 to 0.05 mm consisting of at least 100% of nitride, a cubic boron nitride-based mixed powder or a green compact thereof is placed adjacently through the intermediate layer, and then the whole is coated with a 40Kb A method for manufacturing a composite sintered member for a cutting tool, characterized in that sintering is carried out by heating and holding at a temperature of 1200° C. or higher under the above-mentioned high pressure.