JPS6114106B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ultra-high pressure sintered material that has excellent toughness and heat and wear resistance, and is particularly suitable for use as a material for cutting tools. Generally used for cutting tools used to cut ferrous metal materials such as cast iron, non-ferrous metal materials such as aluminum, aluminum alloys, copper, and copper alloys, and non-metallic materials such as plastics, rubber, graphite, and ceramics. are required to have properties such as high hardness, excellent wear resistance, toughness, and thermal and chemical stability. In recent years, in order to satisfy such demands, ultra-high pressure sintered materials whose main component is diamond have been proposed, and the ultra-high pressure sintered materials have high hardness not only at room temperature but also at relatively high temperatures, and have excellent properties. Because it exhibits wear resistance, it is used as a material for finishing cutting tools under harsh conditions such as impact. It is true that the above-mentioned cutting tool made of ultra-high pressure sintered material enables high-speed cutting when cutting the above-mentioned ferrous metal materials and non-ferrous metal materials, making it difficult for built-up edges to stick and providing an excellent finished surface. This brings about the advantage of In this way, the conventional ultra-high pressure sintered materials mentioned above are mainly composed of diamond which has extremely high hardness, so they can be used as cutting tools for cutting the above-mentioned ferrous metal materials, non-ferrous metal materials, and non-metal materials. Although it shows excellent wear resistance when used,
Because it does not have sufficient toughness, chipping wear is likely to occur during cutting due to this lack of toughness, and as a result, the excellent wear resistance that it originally has cannot be fully demonstrated, and the Currently, it cannot be used for cutting that involves a rise in temperature because it does not have high-temperature oxidation resistance. From the above-mentioned viewpoint, the present inventors have determined that toughness,
In order to obtain materials for cutting tools that have both high-temperature oxidation resistance (heat resistance) and wear resistance, we conducted research focusing on diamond. one of group metal carbides, nitrides, carbonitrides, and borides
Powder consisting of a species or two or more species (hereinafter collectively referred to as metal carbon/nitrogen/boride) and one of the silicides of metals from groups 4a, 5a, and 6a of the periodic table. Alternatively, when a mixture of two or more types of powder (hereinafter collectively referred to as metal silicides) is used as a raw material powder and ultra-high pressure sintering is performed, the diamond particles are mixed together, and the carbon and nitrogen of the metals are mixed together. - There is no mutual contact between the boride particles and the silicide particles of the above metal, and the diamond particles, the carbon/nitrogen/boride particles of the above metal, and the silicide particles of the above metal are adjacent to each other, and A sintered material with a dense structure in which the components constituting each particle diffuses at the grain boundaries and strong interparticle bonds are formed is obtained. This provides excellent wear resistance, and the excellent toughness and high-temperature oxidation resistance (heat resistance) provided by metal carbon/nitrogen/boride particles and metal silicide particles.
We obtained the knowledge that it combines the following. Therefore, the ultra-high pressure sintered material of the present invention was made based on the above knowledge, and in terms of volume %, diamond: more than 80% to 85%, metal carbon/nitride/boride: 10 to 15%. Less than 5% to 10% of metal silicides and unavoidable impurities
It is characterized by having a composition consisting of less than or equal to: Next, in the ultra-high pressure sintered material of this invention,
The reason why the component composition range is limited as described above will be explained. (a) Diamond As is well known, diamond itself has a Mohs hardness of 10 and a Knoop hardness of 8000 Kg/mm ² or more, making it the hardest substance in existence. If the content is less than 80% by volume, the desired wear resistance cannot be achieved, while if the content exceeds 85% by volume, the degree of contact between the diamond particles increases, and the carbon of the metal, which is particularly tough, increases.・Nitrogen/boride particles and especially metal silicide particles with excellent high-temperature oxidation resistance (heat resistance) do not have strong interparticle bonds with diamond particles, resulting in decreased toughness and chipping during cutting. Since wear tends to occur, the content was set at 80% to 85% by volume. In addition, in producing the ultra-high pressure sintered material of this invention, the diamond powder used as the raw material powder has an average particle size of
It is preferable to use powder having a particle size of 50 μm or less, generally 10 μm or less, and commercially available metal-coated diamond powder may also be used as the raw material powder. (b) Metallic carbon, nitride, and borides For example, titanium carbide (hereinafter referred to as TiC) has a melting point of 3147℃ and a microhardness of 3000Kg/mm ² (load
100g), titanium nitride (hereinafter referred to as TiN) has a melting point:
3205℃, microhardness: 2000Kg/mm ² , melting point of titanium boride (hereinafter referred to as TiB ₂ ): 2980℃, microhardness:
Metal charcoal and carbon, each having 3400Kg/ ^mm2
Nitrogen and borides all have high melting points and high hardness, and are substances with better oxidation resistance at high temperatures than diamond.Moreover, metals such as carbon, nitride, and borides have a high melting point and high hardness, and as mentioned above, sintering Sometimes, it has the effect of causing grain boundary diffusion between diamond particles and metal silicide particles to form strong interparticle bonds. It has the effect of forming a dense structure in which diamond coexists with metal silicide particles, but if the diamond content is less than 10% by volume, the diamond content becomes relatively too large, which is not desirable for the above effect. On the other hand, if the content exceeds 15% by volume, the diamond content becomes relatively too small and the high hardness of diamond is lost. The content was set at less than 10 to 15% by volume because it could not be sufficiently reflected in the sintered material, resulting in a decrease in wear resistance. Further, in producing the ultra-high pressure sintered material of the present invention, the metal carbon/nitrogen/boride powder used as the raw material powder is preferably fine powder, with an average particle size of 10 μm.
It is desirable to use fine powder of less than m. (c) Metal silicides All metal silicides have high melting points, for example, Ti ₅ Si ₃ has a melting point of 2120°C.
Moreover, it is a substance with excellent oxidation resistance at high temperatures compared to diamond and metal carbon, nitride, and borides. Because it is soft, it is easily deformed during ultra-high pressure sintering, and it also creates slippage between particles, densely filling in the spaces between diamond particles and metal carbon, nitride, and boride particles, resulting in improved toughness. However, if the content is less than 5% by volume, metal charcoal and
Similar to nitride and boride, the diamond content becomes relatively too large, making it impossible to obtain the desired effect in the above action, resulting in a decrease in toughness. % or more, the diamond content becomes relatively too small and the high hardness of diamond cannot be fully reflected in the sintered material, resulting in a decrease in wear resistance. Its content was set at less than 5-10% by volume. Further, in producing the ultra-high pressure sintered material of the present invention, the metal silicide powder used as the raw material powder is preferably fine, and it is desirable to use fine powder with an average particle size of 10 μm or less. Further, the ultra-high pressure sintered material of the present invention can be manufactured by a conventional powder metallurgy method using a known ultra-high pressure and ultra-high temperature generator. That is, diamond powder as raw material powder, metal carbon/nitrogen/boride powder, and metal silicide powder are blended in a predetermined ratio, and this blended powder is mixed for a long time in a mixer such as an iron ball mill to form a homogeneous powder. This mixed powder is then sealed in a container made of steel or a high melting point metal in an ultra-high pressure and high temperature generator as described in Japanese Patent Publication No. 36-23463, and the pressure and temperature are increased. Maximum pressure: 54-70kb, maximum temperature: 1400
Several minutes to several 1 at pressure and temperature within the range of ~1800℃
It can be produced by a basic process consisting of holding for a minute, cooling and finally releasing the pressure. Next, the ultra-high pressure sintered material of the present invention will be explained using examples. Example 1 As raw material powder, each commercially available average particle size of 3μ
Diamond powder: 83% by volume, 3.0μm
TiC powder: 10% by volume and 2 μm Ti ₅ Si ₃ powder: 7% by volume were mixed, and this mixed powder was mixed for 4 hours using acetone as a solvent in a ball mill made of cemented carbide. Dry. Next, this mixed powder was packed into a stainless steel (JIS/SUS304) tube with a diameter of 10 mmφ and a height of 10 mm, and cemented carbide (P20) lids were welded to both ends of the tube while vacuuming. The tube was sealed. The tube filled with the above mixed powder and sealed in this way is
It was installed in a known ultra-high pressure and high temperature generator and sintered at a maximum applied pressure of 60 kb and a maximum heating temperature of 1450°C for 10 minutes, then cooled and released the pressure to produce the results shown in Table 1. An ultra-high pressure sintered material of the present invention (hereinafter referred to as the "present invention material") 1 having the component composition shown in was produced. The resulting material 1 of the present invention had a dense structure in which diamond, TiC, and Ti ₅ Si ₃ were uniformly dispersed. Next, for the purpose of comparison, as shown in Table 1, comparative ultra-high pressure sintered materials (hereinafter referred to as comparative materials) 1 to 1 having component compositions outside the scope of the present invention were used.
Material No. 6 was produced under the same conditions as applied to the production of Inventive Material 1 above, except that the mixing ratio of the raw material powders was changed so that the final component composition was as shown in Table 1. Next, from the above-mentioned Invention Material 1, Comparative Materials 1 to 6, and a conventionally known ultra-high pressure sintered material whose main component is diamond (hereinafter referred to as conventional material) prepared for the purpose of comparison, cutting and polishing were performed. Then, a cutting edge is cut out, and this cutting edge is brazed to a tungsten carbide-based cemented carbide chip using silver solder, thereby producing a cutting tool 1 made of the material of the present invention.
Cutting tools 1 to 6 made of comparative materials and cutting tools made of conventional materials were manufactured, respectively.

[Table] Using the various cutting tools obtained above, finish surface machining of cast iron parts under the following conditions: cutting speed: 250 m/min, feed: 0.1 mm/rev., depth of cut: 0.7 mm, cutting oil: used. The number of parts that could be machined with each of the above-mentioned cutting tools until their service life was reached was measured, and the finished surface roughness was also measured. The results are shown in Table 2.

[Table] As shown in Table 2, when the material of the present invention is used as a cutting tool, it has an extremely superior cutting ability compared to comparative materials and conventional materials having compositions outside the scope of the present invention. It is clear that the characteristics, namely tool life and finished surface roughness, are shown. Example 2 The blended powders were commercially available diamond powder with an average particle size of 3 μm: 82% by volume, and TiC with an average particle size of 2.0 μm.
Powder: 5% by volume, 3.0 μm TaC powder: 6% by volume, and 5.0 μm Ta ₅ Si ₃ powder: 7% by volume, except that the sintering holding time was 1 hour. Inventive material 2 was produced under the same conditions as in the production of inventive material 1, having substantially the same final component composition as the blended powder composition. A cutting tool was manufactured from this invention material 2 and the same conventional material as shown in Example 1 under the same conditions as in Example 1, and this cutting tool was used to drill holes in an aluminum alloy member, When measuring the number of parts that could be machined over the life of the tool, the cutting tool made of Inventive Material 2 machined 60,000 pieces, while the cutting tool made from the conventional material only machined 13,000 pieces. It is clear that the material of the invention has excellent cutting properties. Example 3 All blended powders were commercially available with an average particle size of 1.0 μm.
Diamond powder: 84% by volume, same 0.5μm WC
Powder: 10% by volume, 2.0μm _Mo5Si3 powder: 3% _by volume, and _{3.0μm Ti5Si3} powder: 3% by volume
The blended powder was mixed in a cemented carbide ball mill for 10 hours using acetone as a solvent, but under substantially the same conditions as in Example 1 to produce Inventive Material 1. Inventive material 3 having the same final component composition as the above-mentioned blended powder composition was produced. Next, using a cutting tool made of the present invention material 3 manufactured in the same manner as in Example 1 and a cutting tool made of the above-mentioned conventional material, cutting speed: 400 m/min, feed: 0.1 mm/rev., depth of cut: 0.2 mm. A continuous cutting test was conducted under the conditions of , cutting oil: none, and the cutting time until the flank wear width of the cutting tool reached 0.2 mm.
While it took 110 min, cutting tools made from conventional materials reached the wear width in an extremely short 14 min. This result shows that the material of the present invention has extremely excellent cutting properties. As mentioned above, the ultra-high pressure sintered material of this invention is
Because it has excellent toughness, high-temperature oxidation resistance (heat resistance), and wear resistance, it exhibits excellent cutting performance especially when used as a material for cutting tools.

Claims (1)

[Claims] 1. Diamond: more than 80% to 85%, one or more of carbides, nitrides, carbonitrides, and borides of metals from groups 4a, 5a, and 6a of the periodic table: 10% to less than 15%, one or more of silicides of metals of groups 4a, 5a, and 6a of the periodic table: 5% to less than 10% (volume %). A heat-resistant, wear-resistant, ultra-high-pressure sintered material with toughness.