JPS6143307B2 - - 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-metal 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 (heat resistance). From the above-mentioned viewpoint, the present inventors have determined that toughness,
In order to obtain a material for cutting tools that has both high-temperature oxidation resistance (heat resistance) and wear resistance, we conducted research focusing on diamond. ) Powder and one or more of carbides of metals from groups 4a, 5a, and 6a of the periodic table, nitrides and carbonitrides of metals from groups 4a and 5a, and borides of metals from group 4a. (Hereinafter, these will be collectively referred to as metallic charcoal and
powder of titanium silicide (titanium silicide includes Ti ₅ Si ₃ and TiSi ₂ , but will be referred to as Ti ₅ Si ₃ below), and powder of boron carbide. Silicon carbide ( _hereinafter referred to as SiC), and silicon nitride (hereinafter referred to as Si ₃ N ₄ )
When a powder consisting of one or more of the following (hereinafter collectively referred to as carbon/nitride) is used as a raw material powder and subjected to ultra-high pressure sintering, diamond particles are formed. There is no mutual contact between CBN particles, metal carbon/nitrogen/boride particles, titanium silicide particles, and carbon/nitride particles, and diamond particles, CBN particles,
Metallic carbon/nitride/boride particles, titanium silicide particles, and carbon/nitride particles are adjacent to each other,
Moreover, 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, and the ultra-high pressure sintered material obtained as a result is Excellent wear resistance provided by diamond particles and CBN particles,
They found that the material combines the excellent toughness and high-temperature oxidation resistance (heat resistance) provided by metal carbon/nitride/boride particles, titanium silicide particles, and carbon/nitride particles. Therefore, this invention was made based on the above knowledge, and in volume %, diamond: 10 to 70%, CBN: 5 to 50%, metal carbon/nitrogen/boride: 1 to 30%, Ultra-high pressure sintering for cutting tools with a composition of titanium silicide: 0.1-10%, carbon/nitrides and unavoidable impurities: 1-30%, and has excellent toughness, heat resistance, and wear resistance. The material has characteristics. Next, in the ultra-high pressure sintered material of this invention,
The reason why the component composition range was limited as described above will be explained. (a) Diamond Diamond itself has a Mohs hardness of 10 and a Knoop hardness of 8000 kg/mm ² (load of 100 kg).
g) and has the highest hardness among existing substances, but if the content is less than 10% by volume, the desired wear resistance cannot be secured; If the content exceeds the amount, the degree of contact between the diamond particles increases,
Carbon/nitrogen/boride particles, which are metals with particularly high toughness, and CBN particles, which have particularly excellent high-temperature oxidation resistance,
Titanium silicide particles and carbon/nitride particles,
Strong interparticle bonding with diamond particles becomes insufficient, resulting in a decrease in toughness and making chipping wear more likely to occur during cutting.
Its content was determined to be 10 to 70% by volume. The content is preferably 30 to 50% 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 one with a diameter,
Furthermore, commercially available metal-coated diamond powder may be used as the raw material powder. (b) CBN CBN has a temperature of 1200℃ or more, a pressure of 40Kb or more,
It is preferably synthesized at a temperature of 1,800℃ or higher and a pressure of 60Kb or higher, and has a hardness second only to diamond, i.e., 6,000 to 7,000 on the Vickers hardness.
Kg/mm ² and has properties that are more stable at higher temperatures than diamond and less reactive with iron group metals. Oxidation resistance and reaction resistance to iron group metals cannot be ensured, and on the other hand, if the content exceeds 50% by volume, the diamond content becomes relatively too small, and the high hardness of diamond is quenched. This is because the wear resistance cannot be sufficiently reflected in the bonding material, resulting in a decrease in wear resistance.
Its content was set at 5 to 50% by volume. Note that the content is preferably 20 to 35% by volume. (c) 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 of 100
g), Titanium nitride (hereinafter referred to as TiN) has a melting point:
3205℃, microhardness: 2000Kg/mm ² , titanium boride (hereinafter referred to as TiB ₂ ) has a melting point of 2980℃, microhardness:
3400Kg/mm ² , the metals carbon, nitride, and borides all have high melting points and high hardness, and are substances with excellent oxidation resistance at high temperatures compared to diamond.・As mentioned above, for nitride/boride, grain boundary diffusion occurs between diamond particles, CBN particles, titanium silicide particles, and carbon/nitride particles during sintering to form strong interparticle bonds. In addition to its excellent sinterability, it forms a dense structure in which the spaces between diamond particles are filled with CBN particles, titanium silicide particles, and carbon/nitride particles. ,
It has the effect of contributing to toughness, but its content is 1
If the diamond content is less than 30% by volume, the desired effect cannot be achieved, while if the content exceeds 30% by volume, the diamond content will be relatively small, making it difficult to apply the high hardness of diamond to the sintered material. The content was determined to be 1 to 30% by volume, since this would result in a decrease in wear resistance. In addition, when manufacturing the ultra-high pressure sintered material of this invention, metal charcoal and
The nitrogen/boride powder is preferably a fine powder, and it is desirable to use a fine powder with an average particle size of 10 μm or less. (d) Titanium silicide For example, titanium silicide has a high melting point, as Ti ₅ Si ₃ has a melting point of 2120°C, and moreover, it can be used at higher temperatures than diamond and metal carbon, nitride, and borides. It is a material with excellent oxidation resistance, and is also highly resistant to diamond, CBN, metal charcoal,
Because they are softer than nitride/borides and carbon/nitrides, they are easily deformed during ultra-high pressure sintering, and stagnation occurs between particles, resulting in diamond particles, CBN particles, and carbon/nitrides in metals. It has the effect of densely filling boride particles and carbon/nitride particles, thereby improving toughness, but if the content is less than 0.1% by volume, the desired effect cannot be obtained. is not possible, while 10
If the diamond content exceeds 0.1 to 10% by volume, the content of diamond becomes relatively small, making it impossible to secure the desired wear resistance. Therefore, the content was set at 0.1 to 10% by volume. Note that the content is preferably 2 to 6% by volume. (e) Carbon/Nitride For example, SiC has a melting point of 2827℃ and a minute Knoop hardness of 3000Kg/mm ² (load: 100g). All of these carbons and nitrides have a high melting point and high hardness. , is a material with superior oxidation resistance at high temperatures compared to diamond, and carbon/nitrides also contain diamond particles, CBN particles, metal carbon/nitride/boride particles, In addition to contributing to component diffusion at the mutual grain boundaries of titanium silicide particles and forming strong interparticle bonds, CBN particles also have excellent sintering properties, so CBN particles connect diamond particles to each other. , has the effect of contributing to improving toughness by forming a dense structure in coexistence with metallic carbon/nitrogen/boride particles and titanium silicide particles, but if its content is less than 1% by volume, The desired effect cannot be obtained from the above action, while 30
If the content exceeds % by volume, the diamond content will be relatively low, and the high hardness of diamond will not be fully reflected in the sintered material, resulting in a decrease in wear resistance. Therefore, its content was determined to be 1 to 30% by volume. In the production of the ultra-high pressure sintered material of the present invention, the carbon/nitride powder used as the raw material powder and the titanium silicide powder described above are desirably the same as the metal carbon/nitride/boride powder. It is preferable 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, raw material powders such as diamond powder, CBN powder, metal carbon/nitrogen/boride powder, titanium silicide powder, and carbon/nitride powder are blended in a predetermined ratio, and this blended powder is passed through a mixing machine such as an iron ball mill. The mixed powder is mixed for a long time to form a homogeneous mixed powder, and then this mixed powder is sealed in a steel or high melting point metal container in an ultra-high pressure and high temperature generator as described in Japanese Patent Publication No. 36-23463. and increase the pressure and temperature, maximum pressure: 54~70Kb, maximum temperature:
It can be produced by a basic process consisting of holding at a pressure and temperature in the range 1400-1800° C. 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. As raw material powder, each commercially available average particle size: 3
Diamond powder with 6 μm
CBN powder, carbon/nitrogen/boride powder of various metals with an average particle size within the range of 0.2 to 2 μm, Ti ₅ Si ₃ powder of 3 μm, SiC powder of 3 μm, B ₄ C of 4 μm powder, and the same 2 μm
Si ₃ N ₄ powder was prepared, these raw material powders were each blended into the composition shown in Table 1, acetone was added as a solvent, and the mixture was mixed for 4 hours in a ball mill made of tungsten carbide-based cemented carbide. After drying, it is packed into a stainless steel (JIS/SUS304) tube with dimensions of diameter: 10 mm x height: 10 mm, and a JIS/p20 tungsten carbide-based cemented carbide lid is attached to the tube while vacuuming. Both ends are welded and sealed, and then this is attached to a known ultra-high pressure and high temperature generator, maximum applied pressure: 60Kb, maximum heating temperature:
The ultra-high pressure sintered materials 1 to 18 of the present invention, which have substantially the same composition as the blended composition, are obtained by holding and sintering at 1450°C for 10 minutes, cooling, and releasing the pressure. and comparative ultra-high pressure sintered materials 1 to 8 were produced, respectively. The resulting ultra-high pressure sintered materials 1 to 18 of the present invention
are diamond, CBN, metal charcoal,
It had a dense structure in which nitride/boride, Ti ₅ Si ₃ , and carbon/nitride were uniformly dispersed. Comparative ultra-high pressure sintered materials 1 to 8 all have compositions in which the content of at least one of the constituent components (marked with * in Table 1) is outside the scope of the present invention. It is something. 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 whose main component is diamond and have the compositions shown in Table 1, are cut into cutting edges by cutting and polishing. , with this cutting edge brazed to a tungsten carbide-based cemented carbide chip using silver solder, work material: FC30, cutting speed: 200 m/min, depth of cut: 1 mm, cutting oil: None, under the following conditions. Cutting test for finishing surface of cast iron, and workpiece material: Al-Si alloy (Si: 8% by weight), cutting speed: 300m/min, feed: 0.1mm/rev., depth of cut: 0.5mm,

【table】

[Table] Cutting tests were conducted to finish the surface of Al alloys under the conditions of no cutting oil and , and in each cutting test, the cutting time until the flank wear width of the cutting edge reached 0.2 mm was measured. The results of these measurements are shown in Table 1. From the results shown in Table 1, ultra-high pressure sintered materials 1 to 18 of the present invention all have significantly superior toughness and heat resistance compared to commercially available ultra-high pressure sintered materials, and are equivalent to these. Because of its excellent wear resistance, it exhibits extremely long cutting times;
It is evident that commercially available ultra-high pressure sintered materials exhibit relatively short cutting times due to lack of toughness and heat resistance. Furthermore, as seen in Comparative Ultra-High Pressure Sintered Materials 1 to 8, if the content of at least one of the constituent components falls outside the scope of the present invention, the toughness, heat resistance, and wear resistance may deteriorate. Since at least one of the properties is inferior, it does not exhibit the desired cutting performance and exhibits only a relatively short cutting time. As mentioned above, the ultra-high pressure sintered material of this invention is
Since it has excellent toughness, heat resistance (high temperature oxidation resistance), and wear resistance, it exhibits excellent cutting performance especially when used as a material for cutting tools.

Claims (1)

[Claims] 1 Diamond: 10 to 70%, cubic boron nitride: 5 to 50%, carbides of metals from groups 4a, 5a, and 6a of the periodic table,
One or two of nitrides and carbonitrides of group 4a and 5a metals, and borides of group 4a metals.
More than species: 1 to 30%, Titanium silicide: 0.1 to 10%, One or more of boron carbide, silicon carbide, and silicon nitride and inevitable impurities:
An ultra-high pressure sintered material for cutting tools having excellent toughness and heat and wear resistance, characterized by having a composition (volume %) consisting of 1 to 30%.