JPS627148B2 - - 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 gives you the advantage of being able to 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. carbides of group metals, and one or more types of carbonitrides of group 4a and 5a metals (hereinafter collectively referred to as metal carbonitrides, TiC, ZrC,
HfC, VC, TaC, NbC, _Mo2C , WC, _{Cr3C2 ,}
TiCN, ZrCN, HfCN, VCN, TaCN, and
When ultra-high pressure sintering is performed using a blend of powder consisting of NbCN) as the raw material powder, there is no mutual contact between the diamond particles and the carbon/nitride particles of the above metals, and the diamond particles and the above metals are not in contact with each other. A sintered material with a dense structure is obtained in which the carbon/nitride particles are adjacent to each other, and the components constituting each particle are diffused at the grain boundaries to form strong interparticle bonds. and the resulting sintered material combines the excellent wear resistance provided by the diamond particles with the excellent toughness and heat resistance provided by the metallic carbon/nitride particles. I got it. 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 90%, metal carbon/nitride and inevitable impurities: 10 to 20
It is characterized by having a composition consisting of less than %. 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.
It is a substance with the highest hardness among existing substances, but if its content is less than 80% by volume, the desired extremely high wear resistance cannot be achieved, but if it is contained in excess of 90% by volume. , the degree of contact between diamond particles increases,
The strong interparticle bond between the metal carbon/nitride particles, which have excellent heat resistance and high toughness, and the diamond particles becomes insufficient, resulting in a decrease in toughness and making chipping wear more likely to occur during cutting. The content was determined to be more than 80% by volume to 90% by volume. In addition, in the production of the ultra-high pressure sintered material of this invention, the diamond powder used as the raw material powder has an average particle size of 50 μm or less, generally 10 μm or less, in order to ensure excellent sinterability. It is preferable to use diamond powder with a metal coating, and commercially available metal-coated diamond powder may also be used as the raw material powder. (b) Metallic carbon/nitride For example, TiC has a melting point of 3147°C and a micro-Vickers hardness of 3000 Kg/mm ² (load of 100 g), and TaC has a melting point of 3985°C and a micro-Vickers hardness of 2380
Kg/mm ² , and TiCN has a decomposition temperature of 3050°C and a microvitkers hardness of 2600 Kg/mm ² , so metal carbons and nitrides both have high melting points and high hardness, and are hard compared to diamond. It is a substance with excellent oxidation resistance at high temperatures, and as mentioned above, metal carbon and nitrides create strong interparticle bonds by causing grain boundary diffusion with diamond particles during sintering. In addition to having the effect of forming a
It has the effect of forming a dense structure filled with nitride particles, but if the content is less than 10%, the diamond content becomes relatively too large and the desired effect cannot be obtained. As a result, the toughness decreases, and on the other hand, when the diamond content exceeds 20%, the diamond content becomes relatively less than 80%, and the high hardness of diamond is not fully reflected in the sintered material. As a result, the desired extremely high wear resistance could not be secured, so the content was set to less than 10 to 20% by volume. Further, in producing the ultra-high pressure sintered material of the present invention, the metal carbon/nitride powder used as the raw material powder is preferably fine powder, with an average particle size of 10
It is desirable to use fine powder of micrometers 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 a raw material powder and metal carbon/nitride 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 mixed powder. Powder, for example,
It is sealed in a container made of steel or high melting point metal in an ultra-high pressure and high temperature generator as described in Publication No. 23463, and the pressure and temperature are raised to achieve a maximum pressure of 54 to 70 Kb and a maximum temperature of 1400 to 1800°C. It can be produced by a basic process consisting of holding at a pressure and temperature range for a few minutes to several tens of minutes, then cooling and finally releasing the pressure. Next, the ultra-high pressure sintered material of the present invention will be explained using examples. Examples As raw material powders, commercially available diamond powder, TiC powder, ZrC powder, HfC powder, VC powder, all having a predetermined average particle size within the range of 1 to 3 μm,
TaC powder, NbC powder, _Mo2C powder, WC powder,
Prepare Cr ₃ C ₂ powder, TiCN powder, ZrCN powder, HfCN powder, VCN powder, TaCN powder, and NbCN powder, blend these raw powders to the composition shown in Table 1, and apply this blended powder to WC. After mixing for 4 hours using acetone as a solvent in a ball mill made of base cemented carbide, the mixture was dried. Then,
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 lids made of WC-based cemented carbide (P20) were welded to both ends of the tube while vacuuming. , the tube was sealed. In this way, the tube filled with the above mixed powder and sealed,
By attaching it to a known ultra-high pressure and high temperature generator and holding it for 10 minutes at a maximum applied pressure of 60 Kb and a maximum heating temperature of 1450°C for sintering, cooling and releasing the pressure, the Ultra-high pressure sintered materials 1 to 17 of the present invention having the same composition as the blended composition were produced. The resulting ultra-high pressure sintered materials 1 to 17 of the present invention
All had a dense structure in which diamond grains and metal carbon/nitride grains were uniformly dispersed.

【table】

[Table] Next, a cutting edge was cut out from the ultra-high pressure sintered materials 1 to 17 of the present invention and a commercially available ultra-high pressure sintered material whose main component is diamond by a cutting and polishing means. The blade is brazed to a WC-based cemented carbide chip using silver solder, and this is attached to the drill body to create a drilling drill.Work material: cast iron (FC-30), machining speed. A drilling test was conducted on cast iron under the conditions of : 150 m/min, and the number of holes drilled until the end of the service life was measured, as well as the finished surface roughness of the drilled surface. 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 17 of the present invention all have excellent wear resistance, toughness, and heat resistance, and therefore exhibit excellent cutting performance over an extremely long period of time. On the other hand, the commercially available ultra-high pressure sintered materials suffer from chipping wear due to insufficient toughness and have a relatively short service life. Further, cutting chips having a shape of SNGN432 were cut from the above-mentioned ultra-high pressure sintered materials 1 to 17 of the present invention and the above-mentioned commercially available ultra-high pressure sintered materials.
Hv1650), Cutting speed: 50m/min, Feed: 0.02m/rev., Depth of cut: 0.15mm, Cutting oil: None, alumina ceramic finishing surface machining test was conducted under the following conditions, and the flank wear width of the cutting edge was 0.3 The cutting time up to mm was measured. This measurement result is the first
Shown in the table. As is clear from the results shown in Table 1, all of the ultra-high pressure sintered materials 1 to 17 of the present invention exhibit long cutting times, which indicates that the ultra-high pressure sintered materials of the present invention have excellent wear resistance. On the other hand, the above-mentioned commercially available ultra-high-pressure sintered materials suffered from defects on the cutting edge due to lack of toughness, and exhibited only a relatively short service life. . 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 90%, carbides of metals from groups 4a, 5a, and 6a of the periodic table;
and one of the carbonitrides of group 4a and 5a metals.
Species or two or more species (hereinafter collectively referred to as metal carbon/nitrides) and unavoidable impurities: 10~
less than 20% (volume %), and there is no mutual contact between diamond particles and metal carbon/nitride particles, and diamond particles and metal carbon/nitride particles are adjacent to each other, A heat-resistant, wear-resistant, ultra-high-pressure cutting tool with toughness characterized by having a dense structure in which the components constituting each particle diffuse at the grain boundaries and form strong interparticle bonds. Sintered material.