JPH0475875B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a material for carbide tools, and more specifically, it is widely used in various carbide tools such as chips, tape cutters, drawing dies, drills, punches, etc. The present invention relates to materials for cemented carbide tools that can be used. [Prior Art and its Problems] Conventionally, tungsten carbide-cobalt alloy (WC-Co) has been mainly used as a material for cemented carbide tools. However, since this tungsten carbide-cobalt alloy contains cobalt,
It has problems of low heat resistance and magnetic properties, and is not necessarily a suitable material for, for example, superalloy cutting tips and tape cutters. Research into cemented carbide tool materials made of ceramics is underway as a solution to this problem, but ceramics generally have the disadvantage of poor toughness. On the other hand, in order to improve the hardness and wear resistance of cemented carbide such as tungsten carbide-cobalt alloy, a coating of hard carbon, that is, diamond or diamond-like carbon, is formed on the surface of the cemented carbide. Carbide tool materials are also known. However, in materials for cemented carbide tools made by coating a hard carbon film on a cemented carbide, it is difficult to say that the adhesion between the cemented carbide and the hard carbon film is sufficient, resulting in the problem that the hard carbon film easily peels off. have. [Objective of the Invention] The object of the present invention is to solve the above-mentioned problems, to avoid the problems of melting point and magnetic properties unlike conventional cemented carbide tool materials, to exhibit a high fracture toughness value, and to have a bond between the base material and the hard carbon film. An object of the present invention is to provide a carbide tool material with excellent adhesion. [Means for achieving the above object] In order to achieve the above object, the inventor has made extensive studies and found that a material made by coating a hard carbon film on a substrate made of specific ceramics has a low melting point and magnetic The inventors have arrived at this invention by discovering that there are no problems with properties, exhibiting high fracture toughness values, and excellent adhesion between the substrate and the hard carbon film, so that it can be suitably used as a cemented carbide tool material. That is, the outline of the present invention is a cemented carbide tool material formed by forming a hard carbon coating on a base made of fiber-reinforced fine ceramics. The fiber-reinforced fine ceramics (hereinafter referred to as
It is sometimes called "FRC". ) is made by using fine ceramics as a matrix and blending inorganic fibers into this matrix. The fine ceramics include aluminum oxide (Al ₂ O ₃ ), zirconia (ZrO ₂ ), yttrium oxide (Y ₂ O ₃ ),
Magnesium oxide (MgO), calcium oxide (CaO), cerium oxide (CeO _{2 ), titanium oxide (TiO 2 )} , chromium oxide (Cr ₂ O ₃ ), silicon dioxide (SiO ₂ ), mullite, apatite, ferrite,
Oxide-based fine ceramics such as spinel,
and non-oxide fins such as silicon carbide, silicon nitride (Si ₃ N ₄ ), boron nitride (BN), boron carbide (B ₄ C), aluminum nitride (AlN), chromium nitride, (CrN), and sialon. Examples include ceramics. Among the fine ceramics,
Oxide-based fine ceramics are preferred, and alumina and a combination of alumina and itria-containing zirconia are particularly preferred. The inorganic fibers are not particularly limited as long as they are inorganic substances in the form of long fibers, short fibers, or whiskers; for example, the fine ceramic whiskers, specifically silicon carbide whiskers,
silicon nitride whiskers or glass fibers,
Examples include carbon fiber and carbon whiskers. Among these, silicon carbide whiskers are preferred. This is because silicon carbide whiskers are particularly effective in improving the mechanical strength of the substrate and the adhesion of the hard carbon coating to the surface of the substrate. Furthermore, a preferred combination of matrix and inorganic fiber is alumina (matrix) and silicon carbide whiskers (inorganic fiber). In obtaining the FRC, the average particle size of the matrix component is usually 3.0 μm or less.
For inorganic fibers, filament diameter 0.1~1.0μ
A material having mφ, a length of 5.0 to 100 μm, and an aspect ratio of 20 to 200 can be suitably used. The above-mentioned FRC is produced by thoroughly kneading each of these components using a kneading machine such as a ball mill or a Banbury mixer, filling the resulting mixture into a predetermined mold, and then heating the mixture at a temperature of 1200 to 2000°C. It can be obtained by sintering. The blending ratio of each component in this mixture is 5 to 40 parts by weight of inorganic fiber per 100 parts by weight of matrix component.
Parts by weight. As a specific example, alumina 100
5 to 40 parts by weight of silicon carbide whiskers
The amount of zirconia is 5 to 40 parts by weight. In this invention, the FRC is used as a base,
A hard carbon coating, ie, a diamond coating or a diamond-like carbon coating, is formed on the surface of this substrate. The hard carbon film can be formed, for example, by bringing a gas obtained by exciting a carbon source gas into contact with the substrate. Examples of the carbon source gas include methane,
Alkanes such as ethane, propane, butane, pentane, hexane, alkenes such as ethylene, propylene, butene, pentene, butadiene, alkynes such as acetylene, aromatic carbonization such as benzene, toluene, xylene, indene, naphthalene, phenanthrene, etc. Hydrogens, cycloparaffins such as cyclopropane and cyclohexane,
Examples include cycloolefins such as cyclopentene and cyclohexene. In addition, oxygen-containing carbon compounds such as carbon monoxide, carbon dioxide, methyl alcohol, ethyl alcohol, acetone, and benzophenone, and nitrogen-containing carbon compounds such as trimethylamine, methylamine, ethylamine, and aniline can also be used as carbon source gases. can. These can be used alone or
Two or more types can also be used in combination. Among these, preferred are paraffinic hydrocarbons such as methane, ethane and propane, ketones such as acetone and benzophenone, and oxygen-containing carbon compounds such as carbon monoxide and methyl alcohol. In forming the hard carbon film, a diluting gas can be used together with the carbon source gas. Examples of the diluting gas include hydrogen gas; inert gases such as helium gas, argon gas, neon gas, xenon gas, and nitrogen gas. These may be used alone or in combination of two or more. Among these, when hydrogen gas is used,
In the plasma CVD method, plasma is formed by high frequency or microwave irradiation, and in the CVD method, atomic hydrogen is formed by heat or electric discharge. This atomic hydrogen has the effect of removing graphite-structured carbon that precipitates simultaneously with the precipitation of diamond or diamond-like carbon. The inert gas can be used, in particular, by a sputtering method,
When an ionization vapor deposition method or an ion beam vapor deposition method is employed, it is used in combination with a carbon source gas consisting of the paraffinic hydrocarbon compound, the oxygen-containing organic compound, and/or the nitrogen-containing organic compound, and is used in the arc discharge space. It has the effect of ionizing carbon by knocking out carbon atoms. When using the diluent gas, the mixing ratio with the carbon source gas is a molar ratio of carbon source gas/diluent gas, which is usually 0.1/100 or more. This mixing ratio
When it is less than 0.1/100, the precipitation rate of hard carbon becomes slow or hard carbon does not precipitate. As a means for exciting the carbon source gas, for example, high frequency plasma CVD method, direct current plasma CVD method, etc.
Conventionally known methods such as a method, a microwave plasma CVD method, a thermal filament method, a chemical transport method, an ion beam method, etc. can be used. In the formation of the hard carbon film, the temperature of the surface of the substrate varies depending on the excitation means for the carbon source gas, so it cannot be determined unconditionally, but for example, when using the micro plasma CVD method, Usually, the temperature is from normal temperature to 1000°C, preferably from normal temperature to 950°C. When the temperature of the substrate surface exceeds 1000°C, the amount of graphite, which is non-diamond-like carbon, increases. The reaction pressure in forming the hard carbon film is:
Usually 10 ^-8 to 10 ³ torr, preferably 10 ^-6 to 800 torr
It is. When the reaction pressure is lower than 10 ^-8 torr, the precipitation rate of hard carbon becomes slow or hard carbon does not precipitate. On the other hand, when the temperature is higher than 10 ³ torr, the amount of graphite generated increases. The carbide tool material of the present invention can be used, for example, in chips, tape cutters, drawing dies, drills, etc.
It can be suitably used for various carbide tools such as punches. [Effects of the Invention] According to the present invention, (1) The substrate is made of fiber-reinforced ceramics, which itself exhibits a high fracture toughness value, and is coated with hard carbon, so it has excellent heat resistance, abrasion resistance, and fracture toughness. (2) Moreover, since the adhesion between the substrate and the hard carbon coating is good, the initial characteristics do not change suddenly and exhibit stable characteristics. Cemented carbide tool materials can be provided. [Example] Next, Examples and Comparative Examples of the present invention will be shown to further specifically explain the present invention. Example 1 100 g of alumina powder (average particle size 0.5 μm), silicon carbide whiskers (filament diameter 0.1 to 1.0 μm)
φ, length 20~100μm, aspect ratio 50~200) 25
g was kneaded for 48 hours using a ball mill to form a mixture. The resulting mixture was filled into a chip mold and sintered at a temperature of 1500° C. using a hot press method to obtain FRC. Next, using this FRC as a base, the base temperature was 900°C.
The output of a microwave power source with a frequency of 2.45 GHz was set to 600 W under the conditions of temperature and pressure of 40 torr. Subsequently, a flow of carbon monoxide is introduced into this reaction chamber.
Hydrogen gas was introduced at a flow rate of 10 sccm and hydrogen gas was introduced at a flow rate of 90 sccm, and diamond was synthesized by microwave plasma CVD for 0.5 hours to obtain a cemented carbide tool material having a coating with a thickness of 3 μm. Here, when we performed Raman spectroscopic analysis on the obtained film, we found that the Raman scattering spectrum was
A peak attributed to diamond was observed near 1333 cm ^-1 , confirming that the diamond was free of impurities. Continuous cutting tests were conducted on chips made of this carbide tool material under the following conditions to evaluate the surface roughness (R _nax ) of the workpiece and the flank wear width of the cutting edge. Work material: Aluminum (A2017BE-T4) Cutting speed: 500 m/min Depth of cut: t = 0.15 mm Feed amount: f = 0.15 mm/rotation Cutting time: 50 minutes The results are shown in Table 1. Example 2 The same procedure as in Example 1 was carried out, except that 10 g of ittria-containing zirconia powder (average particle size: 0.01 μm) was used in addition to the alumina powder and silicon carbide whiskers. The results are shown in Table 1. Comparative Example 1 A cemented carbide tool material was prepared in the same manner as in Example 1, except that no hard carbon coating was formed on the substrate, and the chips made of the obtained carbide tool material were subjected to the same procedure as described above. A continuous cutting test was conducted under the same conditions as in Example 1. The results are shown in Table 1. As is clear from Table 1, the chips of this comparative example were inferior to those of Example 1 in both the surface roughness of the workpiece and the flank wear width of the cutting edge. Comparative Example 2 A continuous cutting test was conducted on a chip made of WC-Co (5% Co content) under the same conditions as in Example 1 above. The results are shown in Table 1. As is clear from Table 1, the chips of this comparative example were inferior to those of Example 1 in both the surface roughness of the workpiece and the flank wear width of the cutting edge. 【table】

Claims (1)

[Claims] 1. A cemented carbide tool material formed by forming a hard carbon coating on a base made of fiber-reinforced fin ceramics.