JPS627267B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a diamond coated cemented carbide tool. Cemented carbide, which has a binder phase mainly composed of iron group metals and contains one or more carbides, is used in a wide range of applications such as cutting tools and wear-resistant tools _. So-called coaching tools coated with a hard material such as O ₃ are rapidly becoming popular. Especially when processing hard materials, the hardness of the tool itself is an important property, and diamond, the hardest substance, is still a valuable material in that sense. Diamond tools are often used in the form of single crystals, sintered bodies, or solidified with metal, other inorganic compounds, or organic materials, but the raw material of diamond itself is expensive, and diamond tools that are harder than these are often used. Since there is no porosity, it is difficult to process, resulting in high manufacturing costs and is also limited in shape. The inventors studied a tool that makes the most of the hard properties of diamond, and arrived at the present invention. To take advantage of diamond's hardness for complex-shaped or large parts, coating from the gas phase is most suitable. In this case, it is desirable for the base material to have a high modulus of elasticity in order to reduce damage to the coating film. Therefore, a cemented carbide whose main component is one or more carbides and/or nitrides is most suitable as a highly elastic base material. If you try to coat the surface of this cemented carbide with diamond using a vapor phase, the presence of a substance that should normally act as a catalyst when synthesizing diamond will not only make it difficult to synthesize diamond, but even if it can be coated, it will be used at high temperatures. In this case, the diamond film undergoes transformation and becomes graphite, making it impossible to utilize its original high hardness. Therefore, it is not preferable to directly coat cemented carbide containing Co or Ni. Therefore, in order to obtain a stable diamond coating film, we propose a coated cemented carbide with an intermediate layer interposed between the cemented carbide and diamond. The intermediate layer must not contain metals such as Fe, Co, and Ni, and it is desirable to use a material that allows these metals to diffuse less. As a result of various studies on the materials for this intermediate layer, we found that the ones that can be stably used industrially as coating materials are those from the periodic table a,
a, carbides, nitrides, oxides, borides, and mixtures and compounds of group a elements, as well as Al ₂ O ₃ ,
It turned out to be AlN, _B4C , _Si3N4 , SiC, _{and SiO2} . Among these, carbide is the most desirable in terms of adhesive strength, but if diamond is coated with other materials as an intermediate layer in this manner, the above-mentioned instability of the diamond film can be solved. If the thickness of the coating made of cemented carbide as a base material is 0.1 μm or less for both the intermediate layer and the diamond film of the outer layer, it will hardly exhibit any effect, but if it exceeds 10 μm, the strength will drop significantly and it will not be suitable as a tool. Furthermore, the effect remains the same whether the coating method is from the gas phase, CVD (chemical vapor deposition) or PVD (physical vapor deposition). Methods for coating diamond include the W filament method, in which a mixed gas flow of hydrogen and hydrocarbon is excited by heating the W filament to a high temperature of approximately 2000°C, and the plasma method, in which it is excited by applying radio frequency or microwave. The so-called CVD method is well known. Also preferred is an ion beam deposition method using an ion beam of carbon ions. Next, a detailed explanation will be given with reference to examples. Example 1 ISO K10 cemented carbide from 0.5mmφ to 0.35mm
A wire drawing die for wire drawing to φ was prepared, and its surface was coated with TiC to a thickness of 1 μm using the CVD method, and then the base material was heated to 850° C. using the CVD method and coated with diamond to a thickness of 1 μm. As a result of using this in actual wire drawing processing, the product of the present invention was able to produce a 28 kg steel wire, whereas the conventional product
The ISO K10 cemented carbide die could only draw 12 kg. Example 2 A SNG432 tool was made from ISO M10 cemented carbide, coated with TiC and diamond at the film thickness shown in Table 1 using the CVD method, and subjected to a cutting test under the following conditions. Cutting conditions: Work material: Al alloy (AA-4032) Speed: 800m/min Depth of cut: 1.0 to 7.0mm Feed: 0.5mm/rev

[Table] As shown in Table 1, by coating a diamond film through an intermediate layer of TiC, the life of a cutting tool is dramatically improved, which is an improvement over cemented carbide coated with only a TiC layer. I know it will happen. Moreover, when the thickness of the coating layer is 10 μm or more, whether it is an intermediate layer or a diamond film, the strength is rather reduced. Example 3 WC-15%Co cemented carbide was coated with the substances shown in Table 2 to a thickness of 2 μm each using the ion plating method, the base material was further heated to 750°C, and 2 μm of diamond was deposited on top of it by ion beam deposition. A coated cemented carbide coated using a dispensing method is prepared, and Al ₂ O ₃ is applied to the surface of the coated cemented carbide.
Press the sintered body at a pressure of 10Kg/mm ² at 150m/min
A wear test was conducted at a speed of 60 minutes to measure the depth of wear on the surface. The results are shown in Table 2. As shown in the table, it can be seen that the wear resistance of the diamond-coated cemented carbide of the present invention is improved in all cases by interposing the intermediate layer.

【table】

[Table] In the above example, an example was shown in which WC-Co cemented carbide was used as the base material, but WC-TiC-Co, WC-TiC-
The same effect can be obtained using TiN-Co based cemented carbide as a base material, and it is a stable and strong coated cemented carbide that can maximize the hardness and wear resistance of diamond, such as cutting tools, dies, rollers, etc. It has high industrial value as a wear-resistant tool.

Claims (1)

[Scope of Claims] 1. A coated cemented carbide whose base material is a cemented carbide containing one or more types of carbide or/and nitride, in which the inner layer adjacent to the base material contains a group a, a, group a element. Carbides, nitrides, borides, oxides and their compounds, mixtures, Al2O3, AlN, B4C,
A diamond-coated cemented carbide tool made of one or more selected from Si3N4 and SiO2, and characterized in that the outer layer is made of diamond. 2 In claim 1, the inner layer has a thickness of 0.1 to 10 μm, and the outer layer has a thickness of 0.1 to 10 μm.
A diamond-coated cemented carbide tool characterized by: