JPS6141873B2 - - Google Patents

Description

[Detailed description of the invention]

This invention is an ultra-high-pressure sintered tool suitable for use as a cutting tool for cutting high-hardness steel, Ni-based or Co-based superalloys, etc., which require high hardness, excellent wear resistance, toughness, and corrosion resistance. This relates to binding materials. Generally, tungsten carbide (hereinafter referred to as WC)-based cemented carbide, which has excellent toughness, has been widely used for the above-mentioned applications.
As the conditions for their use have become more severe in recent years, there has been a strong desire to develop better materials. Recently, in response to such demands, cubic boron nitride ultra-high pressure sintered materials and ultra-high pressure sintered materials containing small amounts of Al and iron group metals have been proposed and commercially available, but the former Although the latter sintered material has excellent wear resistance, it lacks toughness, and the wear resistance of the latter sintered material deteriorates especially when used under conditions of high heat generation. Currently, there are no materials with satisfactory properties. Therefore, from the above-mentioned viewpoints, the present inventors developed a sintered material that has excellent wear resistance and toughness and is particularly suitable for use as a cutting tool. ), and as a result of conducting research, we found that the CBN has 4a of the periodic table,
One or more of the following: carbides of group 5a and 6a metals, nitrides of group 4a and 5a metals, and borides of group 4a metals (hereinafter these are collectively referred to as metal carbons, nitrides, one or more of silicon carbide (hereinafter referred to as SiC), boron carbide (hereinafter referred to as B ₄ C), and silicon nitride (hereinafter referred to as Si ₃ N ₄ ) (hereinafter referred to as carbon/nitride) is an ultra-high pressure sintered material containing
CBN provides excellent wear resistance, and the carbon, nitride, boride, and carbon/nitride of the metals provide excellent toughness. They found that it exhibits excellent cutting performance when used as a cutting tool to cut materials such as super alloys. Therefore, this invention was made based on the above knowledge, and in terms of volume %, CBN: 50 to 90%, metal carbon/nitride/boride: 5 to 45%, carbon/nitride, and It has a composition consisting of unavoidable impurities: 5 to 20%, and is characterized by an ultra-high pressure sintered material for cutting tools having excellent toughness and wear resistance. Next, the reason why the composition range of the sintered material of the present invention is limited as described above will be explained. (a) CBN CBN is synthesized at a temperature of 1,200℃ or higher and a pressure of 40Kb or higher, preferably at a temperature of 1,800℃ or higher and a pressure of 60Kb or higher.It has a hardness second only to diamond, that is, a Bitkers hardness of 6,000 to 7,000Kg/
mm ² and has properties that are more stable at higher temperatures than diamond and are less likely to react with iron group metals. However, if its content is less than 50% by volume, the desired wear resistance may not be achieved. On the other hand, if the content exceeds 90% by volume, sinterability becomes insufficient and residual pores begin to become noticeable, and the toughness decreases significantly, resulting in minute chipping and chipping on the cutting edge. The content was set at 50 to 90% by volume. (b) Metal carbon, nitride, and borides These metal carbon, nitrate, and borides all have high melting points and high hardness, and when they are sintered together with CBN powder under ultra-high pressure and ultra-high temperature, Carbon, nitride, and borides of these metals form a dense structure that sufficiently surrounds CBN particles, and have the effect of significantly improving the toughness of the sintered material, but if their content is less than 5% by volume, the relative If the CBN component content is too high, sinterability becomes insufficient and toughness decreases, while if the content exceeds 45% by volume, the CBN component content becomes relatively too low. Since the high hardness of the CBN component cannot be sufficiently reflected in the sintered material, resulting in a decrease in wear resistance, the content was set at 5 to 45% by volume. (c) Carbon/Nitride For example, SiC has a melting point of 2827℃ and a micro-Vickers hardness (load of 100g): 3340Kg/mm ² , and B ₄ C has a melting point of 2350℃ and a micro-Vickers hardness of 4950
Kg/mm ² , these compounds have a high melting point hardness, and when mixed with CBN powder and sintered at ultra-high pressure and ultra-high temperature, interdiffusion with CBN particles easily occurs, and the particles It has the effect of strengthening the mutual bonding strength and improving the toughness of the sintered material, but if the content is less than 5% by volume, the desired effect cannot be obtained;
If the content exceeds 5, the wear resistance of the sintered material will decrease, so the content should be
It was set at ~20% by volume. Furthermore, the sintered material of the present invention can be produced using a conventionally known ultra-high pressure and ultra-high temperature generator. That is, CBN powder, metal carbon/nitride/boride powder, and carbon/nitride powder are blended in a predetermined ratio, mixed for a long time in an iron ball mill to form a homogeneous mixed powder, and then the above-mentioned mixed powder is mixed. The powder is sealed in a container made of steel or a high-melting point metal, and charged into an ultra-high pressure and ultra-high temperature generator such as that described in Japanese Patent Publication No. 38-14, and the pressure and temperature are raised to produce the final product. Pressure 40~60Kb, temperature 1200~1800℃
It can be manufactured by holding at this maximum pressure and temperature for 0.5 to 10 minutes, and then releasing the pressure after cooling. Next, the ultra-high pressure sintered material of the present invention will be explained with reference to Examples. The raw material powders include CBN powder with an average particle size of 3 μm synthesized by a non-catalytic method, and carbon, nitrogen, and various metals with an average particle size in the range of 0.2 to 3.
Prepare boride powder and carbon/nitride powder, mix these raw material powders to the composition shown in Table 1, and add these mixed powders to WC.
The powder was charged into a small high-speed planetary motion mill lined with base cemented carbide, and 40% by volume of methyl alcohol was added to the blended powder and mixed for 1 hour.
After mixing, the lid of the mill was opened in an argon atmosphere, heated to a temperature of 130°C to evaporate the methyl alcohol, and dried. Then, in the same argon atmosphere, a separately prepared inner diameter: 10 mmφ x height: First, a separately prepared WC-based cemented carbide disk with dimensions of diameter: 9.8 mmφ x thickness: 2 mm was placed in the bottom of a Ti cylindrical container with dimensions of 15 mm. The above-mentioned mixed powder was charged on top so that the thickness was 7 mm, and it was filled by pressing lightly with a push rod, and a 2 mm thick WC-based cemented carbide disk was placed on top of this filled mixed powder. Next, after removing the powder from the argon atmosphere, a Ti top lid is placed on top and pressed to compress the mixed powder in the Ti cylindrical container to a thickness of 5.5 mm, and then the top lid is welded to the cylindrical container. Then, this was sealed, and the cylindrical container filled with the above mixed powder and sealed was placed in a known ultra-high pressure and ultra-high temperature generator, and was heated at a maximum applied pressure of 50 Kb and a maximum heating temperature of 1450°C. After holding the condition for 1 minute, cooling and then releasing the pressure, it is possible to obtain a diffusion bond that has substantially the same composition as the blended composition and is bonded to the upper and lower disks made of the above-mentioned WC-based cemented carbide. Ultra-high pressure sintered material 1 of the present invention in a state of
18 and comparative ultra-high pressure sintered materials 1 to 8, respectively.

【table】

[Table] Manufactured. Note that Comparative Ultra High Pressure Sintered Materials 1 to 8 all have compositions in which the content of at least one of the constituent components is outside the scope of the present invention. Next, the above-mentioned ultra-high pressure sintered materials 1 to 18 of the present invention,
Comparative ultra-high-pressure sintered materials 1 to 8 and commercially available ultra-high-pressure sintered materials having the compositions shown in Table 1 were used to finish cutting edges by cutting and polishing, and then combined with the above-mentioned WC-based cemented carbide disk. In this state, it was fixed to a separately prepared rectangular WC-based cemented carbide chip with silver solder, and the nose radius was finished to 0.4 mm to make a cutting tool. Work material: carburized and quenched steel ( Continuous cutting test of high-hardness steel under the following conditions: Rockwell hardness: 60), cutting speed: 150 m/min, feed: 0.1 mm/rev., depth of cut: 0.5 mm, and work material: Hastelloy X (Ni-based Continuous cutting tests were conducted on Ni-based alloys under the following conditions: cutting speed: 100 m/min, feed: 0.1 mm/rev., depth of cut: 0.2 mm.
In all cutting tests, the flank wear width of the cutting edge was 0.2
The cutting time to reach mm was measured. The results of these measurements are shown in Table 1. From the results shown in Table 1, the ultra-high pressure sintered materials 1 to 18 of the present invention all have excellent toughness and wear resistance, so they are suitable for cutting high-hardness steel and Ni-based alloys that require these properties. It is clear that commercially available ultra-high pressure sintered materials exhibit relatively short cutting times due to lack of wear resistance, whereas they exhibit excellent cutting performance over long periods of time. In addition, as seen in Comparative Ultra-High Pressure Sintered Materials 1 to 8, if the content of any of the constituent components falls outside the scope of the present invention, at least one of the properties of toughness and wear resistance may deteriorate. It is clear that the cutting performance becomes inferior and the desired excellent cutting performance cannot be exhibited for a long period of time. As is clear from the above results, the ultra-high pressure sintered material of this invention has excellent wear resistance and
It has excellent toughness comparable to that of base cemented carbide, so when used as a cutting tool for cutting high-hardness steel or super alloy, it is an excellent tool for a wide range of applications from general cutting to finishing cutting. It demonstrates cutting performance.

Claims (1)

[Scope of Claims] 1. Cubic boron nitride: 50 to 90%, carbides of metals of groups 4a, 5a, and 6a of the periodic table,
One or more nitrides of group 4a and 5a metals, and borides of group 4a metals: 5 to 45
%, one or more of silicon carbide, boron carbide, and silicon nitride and unavoidable impurities:
An ultra-high pressure sintered material for cutting tools having excellent toughness and wear resistance, characterized by having a composition (volume %) consisting of 5 to 20%.