JP2595203B2 - High adhesion diamond coated sintered alloy and method for producing the same - Google Patents

Description

The present invention relates to a method for producing a coated sintered alloy in which a coating layer made of diamond-like carbon and / or diamond having excellent adhesion is formed on the surface of the sintered alloy. In particular, the present invention relates to a method for producing a high-adhesion diamond-coated sintered alloy suitable as a tool component such as a cutting tool and a wear-resistant tool.

(Prior Art) There are roughly two methods for forming a coating layer composed of diamond-like carbon and / or diamond. The first method is to form a coating layer by heating and depositing diamond or carbon. A so-called solid-phase synthesis method, typical examples of which are described in JP-A-53-10394 and
There is one disclosed in JP-A-6-22616. Second,
There is a so-called gas phase synthesis method in which a mixed gas is formed by heating a mixed gas of hydrocarbon and hydrogen to form a coating layer by thermal decomposition of the hydrocarbon.
A typical example is disclosed in Japanese Patent Application Laid-Open No. 58-91100. Research and development for forming a diamond coating layer on the surface of a sintered alloy using these solid-phase synthesis methods and gas-phase synthesis methods have been conducted.

In general, when a coating layer made of diamond-like carbon and / or diamond is formed, carbon also precipitates at the same time as the formation of the coating layer, and amorphous soft carbon tends to be mixed into the coating layer. For this reason, if the coating layer is formed directly on the surface of the sintered alloy containing the iron group metal, the carbon mixed in the coating layer reacts with the iron group metal present on the surface of the sintered alloy and enters the inside of the sintered alloy. There is a problem in the direct formation method of the coating layer that the strength of the sintered alloy is reduced because the solid solution is diffused to generate free carbon. Especially,
When the method of forming the coating layer is a gas phase synthesis method, the iron group metal present on the surface of the sintered alloy serves as a catalyst for decomposing the hydrocarbon gas required for forming the coating layer, Since the amount of soft carbon deposited on the surface of the sintered alloy increases to absorb hydrogen gas, which is effective in removing the soft carbon deposited inside, the diamond coating is hardly formed directly on the surface of the sintered alloy. There is a problem in the forming method. By solving such a problem in the method of directly forming a coating layer, an attempt was made to commercialize a diamond-coated sintered alloy as a tool part in Japanese Patent Application Laid-Open No. 58-122692.
There is an official gazette.

(Problems to be Solved by the Invention) Japanese Patent Application Laid-Open No. 58-122692 discloses that carbides, nitrides, borides, oxides, and oxides of elements of Group 4a, 5a, and 6a of the periodic table are formed on the surface of a cemented carbide. Compounds, mixtures and Al ₂ O ₃ , AlN, B ₄ C, SiC,
After forming at least one inner layer selected from Si ₃ N ₄ and SiO ₂ ,
Further, a diamond-coated cemented carbide in which an outer layer made of diamond is formed on the surface of an inner layer is disclosed. That is, the diamond-coated cemented carbide disclosed in Japanese Patent Application Laid-Open No. 58-122692 has sought to solve the problem on the surface of the cemented carbide by interposing an inner layer between the cemented carbide and the outer layer of diamond. Things. However,
The diamond-coated cemented carbide disclosed in the same publication forms an inner layer on the surface of a cemented carbide, and then, in a step of forming an outer layer made of diamond, cracks in the inner layer due to a difference in thermal expansion between the cemented carbide and the inner layer. There is a problem that enters. In addition, it is necessary to perform the step of forming the coating layer consisting of the inner layer and the outer layer twice, thereby increasing the cost. In addition, the inner layer is formed in a state where the outer layer of diamond is laminated on the flat inner layer. There is a problem that the adhesiveness between the outer layer and the outer layer is low and the outer layer is easily peeled off, and that the formation of the outer layer is slow.

The present invention has solved the above-mentioned problems. Specifically, the present invention corrodes and removes a binder phase present on the surface of a cemented carbide or a sintered alloy made of a cermet, and removes the binder phase from the part. To provide a method for producing a high-adhesion diamond-coated sintered alloy in which an intermediate layer containing diamond-like carbon and / or diamond and an outer layer made of diamond-like carbon and / or diamond are formed on the surface of the intermediate layer. It is the purpose.

(Means for solving the problems) In general, diamond has a very poor wettability with other substances, a low coefficient of thermal expansion, and a small diffusion of other atoms into diamond. It is very difficult to form a coating layer made of diamond-like carbon and / or diamond on the surface. Thus, the present inventors have examined the surface condition of sintered gold suitable for forming a diamond coating layer, and the exact reason is not clear. However, diamond-like carbon and / or diamond The present invention has been completed by finding that, in contrast to the direct formation method of forming a coating layer, the following treatment increases the effect of forming the coating layer.

That is, this finding is based on the finding that the binder phase, particularly the iron group metal, present on the surface of the sintered alloy is corroded and removed, and diamond-like carbon and / or diamond is precipitated in the portion where the binder phase has been removed to form a hard phase and a diamond-like carbon. Carbon and / or
Alternatively, when an intermediate layer containing diamond is formed and an outer layer made of diamond-like carbon and / or diamond is formed on the surface of the intermediate layer, the formation of the outer layer is promoted, and the adhesion between the intermediate layer and the outer layer is improved. After forming the intermediate layer and the outer layer that it is excellent and in this way, further heat treatment in a non-oxidizing gas atmosphere or vacuum,
That is, the strength of the intermediate layer can be increased by exuding the binder phase inside the sintered alloy to the intermediate layer.

The method for producing a high-adhesion diamond-coated sintered alloy according to the present invention comprises the steps of: forming at least one hard layer of carbides, nitrides, borides and their mutual solid solutions of elements of groups 4a, 5a and 6a of the periodic table; , Ni, Co, Cr, Mo, W, by removing the binder phase by corrosion from the surface of the sintered gold consisting of at least one binder phase, the diamond-like carbon and / or Alternatively, after forming an intermediate layer containing diamond, the surface of the intermediate layer is coated with an outer layer made of diamond-like carbon and / or diamond, and then heat-treated in a non-oxidizing gas or in a vacuum. It is a method characterized by the following.

As described above, the method for producing a high-adhesion diamond-coated sintered alloy according to the present invention is characterized in that the diamond-like carbon and / or diamond contained in the intermediate layer act to promote the formation of the outer layer, and the outer layer and the intermediate layer The hard phase and the binder phase contained in the intermediate layer enhance the adhesiveness between the intermediate layer and the sintered alloy, and the diamond-like carbon and / or diamond in the intermediate layer increases the adhesion in the intermediate layer. The intermediate layer and the outer layer have excellent peeling resistance because they are in close contact with each other so as to surround the hard phase.

The outer layer in the method for producing a high-adhesion diamond-coated sintered alloy of the present invention is practically preferably 0.1 μm to 20 μm in thickness, particularly when an impact force is applied, for example, when used as a cutting tool, It is preferable to reduce the thickness of the outer layer from the viewpoint of peeling resistance. Among cutting tools, when used as a cutting tool for rotation, particularly a drill including a micron drill and a sharp-cutting tool such as a reamer end mill, the outer layer is preferably used. It is preferable that the thickness be 0.1 μm to 5 μm.

The intermediate layer in the method for producing a high-adhesion diamond-coated sintered alloy of the present invention is composed of diamond-like carbon and / or diamond, a hard phase and a binder phase, and has excellent peel resistance and excellent strength of the intermediate layer itself. Things. Although the thickness of this intermediate layer is practically 0.1 μm to 10 μm, it is 0.2 μm to 5 μm from the manufacturing process and peeling resistance.
Is a preferred thickness.

The sintered alloy in the method for producing a high-adhesion diamond-coated sintered alloy of the present invention has a surface portion having an engagement phase amount larger than an internal bonding phase amount to increase the surface portion toughness, or vice versa. In addition, the amount of the hard phase on the surface is larger than the amount of the inner hard phase to increase the plastic deformation resistance of the surface, and furthermore, the component composition between the display and the inside is uniform, or the surface of the sintered alloy A part having WC and a binder phase and an inner part consisting of WC, a complex compound and a binder phase can be selectively used.

In the method for producing a high-adhesion diamond-coated sintered alloy of the present invention, the heat treatment conditions vary depending on the component composition of the sintered alloy, but when heated to 900 ° C to 1400 ° C in a stable atmosphere of the outer layer, the inside of the sintered alloy is heated. The binder phase can be exuded to the intermediate layer to increase the strength of the intermediate layer. However, the heat treatment is preferably performed at 900 ° C to 1250 ° C in order to prevent the binder phase oozing into the intermediate layer from eroding the diamond-like carbon and / or diamond in the intermediate layer.

In the method for producing a high-adhesion diamond-coated sintered alloy of the present invention, the method of removing the binder phase from the surface of the sintered alloy is preferably a method based on corrosion. A specific method of the corrosion treatment is, for example, in the case of a sintered alloy containing a binder phase mainly composed of Fe, Ni, Co, an acidic solution such as sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid or aqua regia. There is a method of corroding by immersion, or a method of corroding while electrolyzing in these solutions or other weakly acidic solutions. At this time, the surface of the sintered alloy is a conventionally used abrasive grain or grindstone, for example, diamond, WBN, C
Use BN, silicon carbide or alumina-based abrasive grains or whetstones to make surface roughness less than 0.2μm and then corrode, or corrode the surface of sintered alloy and then make surface roughness less than 0.2μm Is preferable because the nucleation density of diamond is significantly increased in the initial stage of the formation of the outer layer, which is a later step.

The formation of the intermediate layer in the method for producing a high-adhesion diamond-coated sintered alloy of the present invention is carried out by removing the binder phase by corroding the surface of the sintered alloy, and then washing with distilled water or an organic solvent or an ultrasonic cleaner. Then, the surface of the sintered alloy is washed and dried, and then the diamond-like carbon and / or diamond is buried in the bonded phase-removed portion of the surface of the sintered alloy by a conventional diamond synthesis method. At this time, the diamond synthesis method is a preferable method because the diamond-like carbon and / or diamond is easily buried in the portion where the binder phase is removed according to the gas phase synthesis method.

After the formation of the intermediate layer in this manner, when the outer layer is subsequently formed, the diamond-like carbon and / or diamond contained in the intermediate layer becomes a seed crystal for forming the outer layer, thereby promoting the formation of the outer layer.

The diamond-like carbon described here refers to a material that has properties similar to diamond but is not completely diamond by X-ray crystal diffraction.

(Action) In the method for producing a high-adhesion diamond-coated sintered alloy of the present invention, an intermediate layer containing diamond-like carbon and / or diamond, a hard phase and a binder phase is interposed between the sintered alloy and the outer layer. Therefore, the adhesion between the outer layer and the intermediate layer and between the intermediate layer and the sintered alloy is excellent, and therefore, the peel resistance of the outer layer and the intermediate layer is also excellent. In the method for producing a high-adhesion diamond-coated sintered alloy according to the present invention, a dense outer layer is formed because diamond-like carbon and / or diamond contained as an intermediate layer becomes a seed crystal for forming an outer layer. Being done,
In addition, a diamond-coated sintered alloy having excellent wear resistance and impact resistance can be obtained.

(Example) Example 1 Micron drill made of WC-5% Co composition (twist angle 30)
゜, tip angle 120 ゜, cutting edge diameter 0.50φmm) was immersed in 10% HNO ₃ solution for 2 minutes to corrode, washed and dried, and then filament temperature 2000 ℃, 1.5vol% CH ₄ by hot filament method.
The surface of the micron drill was coated with diamond by heating at −98.5 vol% H ₂ gas at 900 ° C. for 2 hours. Then 20ml
Heat treatment was performed at 1100 ° C. for 30 minutes while flowing hydrogen gas at a rate of / min to produce a micron drill of the present invention.

When the micron drill of the present invention thus produced was examined by microscopic observation and X-ray diffraction, the outer layer was made of a dense film-shaped diamond and had a thickness of 1.5 μm. The intermediate layer was a layer in which diamond WC and Co were mixed, and had a thickness of 2.5 μm.

As a comparative product, the surface of a micron drill made of a WC-5% Co alloy was coated with a TiC layer by a CVD method, and then the surface of the TiC layer was coated with an outer layer made of diamond in the same manner as the micron drill of the present invention.

The micron drill of the present invention obtained in this way and the micron drill of the comparative product are a work material in which three multi-layer IC substrates (1.6 mm thick) composed of a copper plate and an epoxy plate are stacked, and the cutting speed is 250 m / mi.
As a result of performing a drilling test under the conditions of n and feed of 0.05 mm / rev, the micron drill of the present invention was able to drill about six times as much as the comparative micron drill.

Example 2 A sintered alloy having a composition of WC-5% TiC-5% TaC-8% Co was formed into a CIS standard SPP432 shape, and this SPP432 was formed into 15% HNO _3.
Immerse in the solution for 1 minute to corrode the surface, and after cleaning and drying,
350W output, 45Tor pressure by microwave plasma CVD
r, coated with diamond in an atmosphere of CH _{4 at} 2 ml / min and H ₂ gas at 200 ml / min, and subsequently heat-treated at 900 ° C. for 30 minutes in an atmosphere of H ₂ gas to produce a product of the present invention.

When the product of the present invention thus produced was examined by microscopy and X-ray diffraction, the outer layer was composed of diamond having a thickness of 1.0 μm, and the intermediate layer was composed of diamond having a thickness of 0.5 μm, WC, composite carbide and Co.

As a comparative product, the surface of a sintered alloy SPP432 composed of WC-5% TiC-5% TaC-6% Co was coated with a TiN layer by a CVD method, and then an outer layer made of diamond was formed in the same manner as the product of the present invention. Coated.

As a result of performing a milling cutting test on a work material of an Al-Si alloy using the obtained product of the present invention and a comparative product under conditions of a cutting speed of 20 m / min and a feed of 0.2 mm / blade, the product of the present invention is as follows. The life was 3.5 times longer than that of the comparative product.

Example 3 An SPP432 was manufactured with a WC-Co composition at a depth of about 50 μm from the surface of a sintered alloy composed of WC-10% TiC-10% TaC-8% Co. This SPP432 was immersed in a 15% HNO ₃ solution for 1.5 minutes to corrode the surface. After washing and drying, diamond coating and subsequent heat treatment were carried out in the same manner as in Example 2 to produce a product of the present invention.

When the product of the present invention thus prepared was examined by microscopy and X-ray diffraction, the outer layer was made of diamond having a thickness of 1.0 μm, the intermediate layer was made of diamond having a thickness of 0.5 μm, and diamond WC and Co were formed.
Consisted of In the sintered alloy, the area adjacent to the intermediate layer was WC and continued to a depth of about 0.5 μm, the area adjacent to the WC hard phase was WC and Co composition, and the interior was composed of WC, Co and composite carbide. Was.

As a comparison, the surface of SPP432 made of the same sintered alloy used in the present invention product was coated with a TiCN layer by a CVD method,
Next, an outer layer made of diamond was coated in the same manner as in the present invention.

Using the thus obtained product of the present invention and the comparative product, a cutting speed of 350 m / min, a feed of 0.15 mm / rev, a depth of cut was applied to the work material using an Al-Si alloy.
As a result of performing a turning test under the condition of 0.35 mm, the product of the present invention showed about 2.5 times the life of the comparative product.

(Effects of the Invention) As described above, the method for producing a high-adhesion diamond-coated sintered alloy of the present invention has excellent adhesion between the outer layer and the intermediate layer and between the intermediate layer and the sintered alloy. It has excellent releasability. For this reason, the present invention can be applied to a cutting tool subjected to a heavy load, for example, a drilling tool such as a milling tool, an end mill, a drill, and a micron drill for a semiconductor substrate, as well as a turning tool. . It is also an industrially useful method that can be applied to wear-resistant tools such as the tip of a print pin or a slitter for cutting paper, tape, or the like.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-123203 (JP, A) JP-A-61-52363 (JP, A) JP-B-51-29987 (JP, B2)

Claims (3)

(57) [Claims] (1) a hard phase of at least one of carbides, nitrides, borides and mutual solid solutions of elements of groups 4a, 5a, 6a of the periodic table and Fe, Ni, Co, Cr, Mo, W The binder phase is removed by corrosion from the surface of the sintered alloy comprising at least one binder phase therein, and an intermediate layer containing diamond-like carbon and / or diamond is formed in a portion where the binder phase has been removed. After that, the surface of the intermediate layer is coated with an outer layer made of diamond-like carbon and / or diamond, and then subjected to a heat treatment in a non-oxidizing gas atmosphere or in a vacuum. Manufacturing method of bonded gold. 2. The high-adhesion diamond-coated ceramic according to claim 1, wherein the corrosion of the binder phase is from 0.1 to 10 μm in depth from the surface of the sintered alloy toward the inside. Manufacturing method of bonded gold. 3. The method for producing a high-adhesion diamond-coated sintered alloy according to claim 1, wherein the heat treatment is performed at 900 ° C. to 1400 ° C.