JPS5935423B2 - Sintered material for cutting tools containing cubic boron nitride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dense sintered material containing cubic boron nitride, which is suitable for use as a cutting tool, particularly for cutting high-hardness steel where excellent wear resistance and toughness are required. It is something.

In recent years, as a sintered material for cutting tools that exhibits relatively good machinability when cutting under severe usage conditions, cubic boron nitride (hereinafter referred to as C-BN) is the main component, and a small amount of A
A sintered material containing J and an iron group metal has been proposed and commercially available, and the sintered material is C-BN, which is stable at high temperatures up to about 1100°C and has a significantly higher hardness second only to diamond. Because it contains as a main component, it has excellent wear resistance and therefore exhibits useful properties when used as a finishing cutting tool.

For example, ordinary tungsten carbide (
Cutting conditions applied when using a base cemented carbide (hereinafter referred to as WC) as a cutting tool are 0, for example, depth of cut = 4 mm, feed rate: 0.4 mrtt/rev.

In particular, when used to cut high-hardness steel, the cutting edge is often damaged due to lack of toughness, making it unusable.

From the viewpoints mentioned above, the present inventors conducted research to impart toughness to the conventionally known C-BN-based sintered material, and as a result, developed the C-BN-based sintered material.

Cubic tantalum nitride (hereinafter referred to as CTaN): 50~
95% by volume (hereinafter % indicates volume%).

carbides of metals of groups 4a, 5a and 6a of the periodic table;
and nitrides of group 4a and 5a metals excluding Ta (hereinafter referred to as Tice ZrC5HfC and VC'5T, respectively)
aCsNbCsCr3C2#MO2C,WC,'riN
.

Contains a high melting point compound consisting of a solid solution of 25 to 50% of one or two of ZrN, HfN, VN, and NbN, collectively referred to as metal layer/nitride. While retaining the excellent wear resistance provided by C-BN, it now has excellent toughness comparable to that of conventional WCC cemented carbide, and therefore it can be used as a substitute for steel, especially high-hardness steel. They found that it can be used for a wide range of cutting, from general cutting to finish cutting, and that it also exhibits useful cutting performance during cutting.

Therefore, this invention was made based on the findings described in J.

C-BN: 20-69.8%.

C-TaN: 50-95%, metal carbon/nitride: 5-5
High melting point compound consisting of solid solution with 0%: 30-79.8
%.

1? , or one of pe, Co, Nis and Si
Seed or 2nd type plate h: Contains io ~ 50%, the rest is Al
Sintering aid metal and inevitable impurities for i alloy consisting of 20.2
~5%.

It is characterized by a C-BN-containing sintered material for cutting tools having a composition consisting of:

Next, in the sintered material of the present invention, the reason why the component composition range is limited to J: as described below will be explained.

(a) C-BN C-BN has a temperature of 1200℃ or higher, a pressure of 40Kb or higher,
It is preferably synthesized at a temperature of 1,800°C or higher and a pressure of 60Kb or higher, has a Vickers hardness of 6,000 to 700 kg/m4), which is second only to diamond, and has properties that are more stable at higher temperatures than diamond. It is a component that has a property of being hard to react with iron group metals, but if its content is less than 20%, the high hardness of C-BN cannot be reflected in the sintered material, and as a result, the desired It was not possible to ensure wear resistance of 69.8%.
If the content exceeds 20%, the viscosity of the sintered material will decrease and high feed cutting will not be possible.
It was set at ~69.8%.

(b) High melting point compound In general, TaN has a hexagonal crystal structure at room temperature, but is stable in a cubic crystal structure under high temperature and high pressure.

Therefore, CTaN can be synthesized by treating, for example, hexagonal TaN in a nitrogen atmosphere in a pressure cooker at a temperature of 900°C and a pressure of 1000 atm. The maximum hardness is approximately 3200 Vickers hardness! 9/mi) and has excellent oxidation resistance.

Moreover, if the metal carbon/nitride listed in L is dissolved in this C-TaN, the hardness will be further improved, but if the content is less than 5% with respect to C-TaN, the desired hardness will not be achieved. On the other hand, if the content exceeds 50%, the effect of improving the toughness of the sintered material brought about by CTaN will be impaired.

The composition of the C-TaN→metallic carbon/nitride solid solution constituting the high melting point compound was determined to be C-TaN: 50-95% and metal carbon/nitride: 5-50%.

Furthermore, if the content of the high melting point compound is less than 30%, the skeleton formation of the C-TaN-metallic carbon/nitride solid solution during sintering is insufficient, making it difficult to impart the desired excellent toughness to the sintered material. On the other hand, if the content exceeds 79.8%, the content of C-BN, which has relatively high hardness, becomes too small and it is impossible to secure the desired excellent wear resistance. The content was determined to be 30 to 79.8%.

(c) Sintering aid metal Al and an alloy having the composition shown in L, which constitute the sintering aid metal, have the effect of promoting sintering and improving the strength of the sintered material, but their content is If the content is less than 0.2%, the desired sintering promotion effect cannot be obtained, while if the content exceeds 5%, the high temperature hardness of the sintered material will decrease, so the content should be reduced to 0.2%. 5%, and the content is preferably 0.5 to 2%.

Note that A[ combines with adsorbed oxygen in the raw material powder during sintering to form aluminum oxide.

A7 and A constituting the sintering aid metal [the alloy does not necessarily exist in the sintered material in a metallic state.

Furthermore, as a sintering aid metal, 0. I: AJli of the following composition
'The toughness of the sintered material is improved when an alloy is used, but the Fe in the alloy.

The content of the alloy component consisting of one or more of Co, Ni, and Si is set at 10 to 50% because if the content is less than 10%, the desired toughness improvement effect cannot be obtained. First, if the content exceeds 50%, the sinterability improvement effect of AA will be impaired.

Moreover, the sintered material of this invention can be used as a raw material powder.

C-BN powder, C-TaN-metallic carbon/nitride solid solution.

fart! Powder and A1 alloy powder are prepared, these raw material powders are blended into a predetermined composition, and mixed for a long time in an iron ball mill to form a homogeneous mixed powder.

The mixed powder is sealed in a container made of steel or a metal with a high melting point, and then charged into an ultra-high pressure and ultra-high temperature generator as described in, for example, Japanese Patent Publication No. 38-14.

By increasing the pressure and temperature, the final pressure is 40 to 60 Kb.
, temperature: 1200-1800<0>C and hold at this final pressure and temperature for 0.5-10 minutes.

It can be manufactured by releasing the pressure after cooling.

Next, the sintered material of the present invention will be specifically explained with reference to Examples.

Example As raw material powder.

Average particle size synthesized by non-catalytic method: 3 μm C-BN powder.

Average particle size: LOpm of C-TaN:50%-TiC:5
0% solid solution powder.

Same 1. oμn C-TaN:95%-NbC:5% solid solution powder.

Same 0.9 pm C-TaN:95%-WC:5% solid solution powder.

Same 1, Opm C-TaN: 60%-ZrC: 20%-
TaC: 20% solid solution powder.

Same 0.9pm C-TaN near 0%-VC:10%-M
O2C: 20% solid solution powder.

Same 0.9pm C-TaN: 60%-TiC: 30%-
WC: 10% solid solution powder.

Same LOpm C-TaN:80%-HfC:5%-Nb
C:5%-Cr3C2:5% solid solution powder.

Same LOpm C-TaN: 60%-TiN: 40%
Solid solution powder.

Same 0.8 pm C-TaN:60%-VN:40% solid solution powder.

Same 0.9pm C-TaN: 65%-TiN: 15%-
NbN: 20% solid solution powder.

Same 0.8pm C-TaN: 50%-ZrC: 30%-
HfN:5%-NbN:15% solid solution powder.

C-TaN of the same LOpm: 60%-TiC215%-T
iN: 25% solid solution powder.

Same 1.0 μm CTaN: 50%-VC: 5%-WC:
30%-NbN:15% solid solution powder.

Same 5μm Al powder.

A#-Co-Ni alloy powder (Co:20
%, Ni: 10% content).

A#-Ni alloy powder (containing 50% Ni) with a diameter of 1.1 μm.

1.0 pm A7-Co alloy powder (Co: 10% content).

Same 1.1μm A#-Ni-Fe alloy powder (N
i: 30%, pe: 10%).

A#-Si alloy powder (Si: 13% content) of 1.2 μm was prepared, and these raw material powders were blended into the composition shown in Table 1, and a small high-speed planetary motion mill with a cemented carbide lining was used. Add methyl alcohol (7) and mix for 1 hour.
After mixing, the lid of the mill was opened in an Ar atmosphere and heated to a temperature of 130°C to evaporate the methyl alcohol and dry the mixture.

In the same <Ar atmosphere, a separately prepared inner diameter of 10 m
At the bottom of a Ti cylindrical container with dimensions of 1 nφ x height 15 mm, a WCC cemented carbide disk with dimensions of 9.8 mm in diameter x 2 mm in thickness, which was also prepared separately, was first charged. ,
Charge the mixed powder described above so that the thickness is 7 mm, press it lightly with a push rod, and fill it with the filled mixed powder. The powder mixture in the Ti cylindrical container was compressed to a thickness of 5.5 mm by covering it with a TiM cap and pressing it, and then removing it from the Ar atmosphere. The container and the lid are sealed by welding, and then the cylindrical container filled with the L mixed powder and sealed is placed in a known ultra-high pressure and ultra-high temperature generator, and the final caloric pressure and By setting the final heating temperature to the conditions shown in Table 1, maintaining these conditions for a predetermined time within the range of 2 to 20 minutes, and performing pressure release and cooling.

Sintered materials 1 to 13 of the present invention having substantially the same composition as the blended composition were manufactured in a state in which they were diffusion bonded to a lower L disk made of WC-based cemented carbide.

Next, the resulting sintered materials 1 to 13 of the present invention were
Cutting and polishing it into a cutting blade, which remains connected to the Ouki cemented carbide disc.

The square-shaped WCC cemented carbide chip was fixed with silver solder prepared separately, and the nose radius was rounded to 0.4 mm. Along with cutting tools made from conventional materials 1 and 2 (hereinafter referred to as conventional materials 1 and 2).

Work material: Die steel (SKDII, hardness: HRC60).

Cutting speed: 100 m/min.

Depth of cut: 0.5mm.

Feed: 0.15mm/rev.

Cutting time: 20m1n.

Continuous cutting tests under the conditions of

Work material: SNCM-8 (hardness: HB400).

Cutting speed: 100 m/min.

Depth of cut = 0.5 mm.

Feed: Q, 25mm/rev-.

Cutting time: 1m1n.

An interrupted cutting test was conducted under the following conditions, and in the continuous cutting test, the flank wear width and rake face wear depth of the cutting edge were measured, and in the interrupted cutting test, the number of fractures among the six test cutting edges was measured. did.

These measurement results are shown in Table 1 together with the Vickers hardness.

From the results shown in Table 1, conventional material 1 (WCC cemented carbide has excellent toughness but poor wear resistance.

On the other hand, all of conventional material 2 (C-BN based sintered material) had cutting edge defects due to lack of toughness, whereas 1. sintered materials 1 to 13 of the present invention all have excellent wear resistance. It is clear that the material has toughness.

As mentioned above, the sintered material of this invention has excellent wear resistance and toughness, making it comparable to steel.

It exhibits excellent performance especially when used as a cutting tool for cutting high-hardness steel.

Claims (1)

[Claims] 1. Cubic boron nitride: ratio 20 to 69.8. Cubic tantalum nitride = 50-95 and 4a of the 9 periodic table
, 5a, and 6a group metal carbides, and one or two of the group 4a and 5a metal nitrides excluding Ta. ~79.8%. Sintering aid metal consisting of Al and inevitable impurities 20, 2-5
%. A sintered material for a cutting tool containing cubic boron nitride, characterized in that it has a composition (volume %) consisting of: 2 Cubic boron nitride: 20-69.8%. Cubic tantalum nitride: 50-95% and 4a of the periodic table
, carbides of group 5a and 6a metals, and nitrides of group 4a and 5a metals excluding Ta.
High melting point compound consisting of solid solution with 5 to 50%
30-79.8%. Sintering aid for A1 alloy containing one or more of Fe, Co, Ni, and Si: 10 to 50%, with the remainder consisting of A metal and inevitable impurities 20, 2 to 50%
A sintered material for cutting tools containing cubic boron nitride, characterized in that it has a composition (capacity %) of 5%.