JPH0665745A - Diamond-coated hard material and its production - Google Patents

Abstract

PURPOSE:To obtain a diamond-coated hard material having excellent adhesion strength, high toughness and high freedom of shape, and to provide its production method. CONSTITUTION:This material consists of a hard material base coated with diamond coating film. The surface of the coated material has smaller compressive stress than the compressive stress of the surface of the base subjected to machining, or the base surface has tensile stress. Further, the diamond-coated hard material consists of a WC-base cemented carbide base body and the compressive stress of the WC phase is smaller than that of the machined base, or the WC phase has <=0.5GPs compressive force. The base body is particularly preferably made of WC cemented carbide. The base body after machining is subjected to blast treatment, barrel treatment and/or heat treatment of hardening and then diamond is applied at least on the treated area of the base body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard material having extremely high wear resistance, and is a diamond-coated hard material used for cutting tools, wear resistant tools, mining tools, electronic parts, machine parts, grindstones and the like. And the manufacturing method thereof.

[0002]

2. Description of the Related Art Diamond has extremely high hardness, is chemically stable, has many excellent characteristics such as high thermal conductivity and sound wave propagation speed. At present, as a polycrystalline diamond on the market, a polycrystalline diamond sintered body having a diamond content of 70% by volume or more and diamond particles bonded to each other, and a diamond coating in which the surface of a hard material is coated with a polycrystalline diamond. Hard materials, ・ Hard materials brazed with diamond poly are the following ~, Al, Al-Si alloys and other light alloys, plastics, rubber, graphite, etc., used for cutting, throwaway tips, drills, Micro drill,
End mills, cutting tools such as routers, rock mining tools, bonding tools, printer heads, dies, various wear resistant tools such as guide rollers for hot working and rolls for pipe making, wear resistant jigs, environment resistant jigs, heat sinks, etc. It is widely used for various machine parts, such as speakers, various diaphragms, various electronic parts, various grinding wheels such as electroplated grinding wheels, and dressers.

A polycrystalline diamond sintered body obtained by sintering fine diamond powder under ultrahigh pressure is disclosed in, for example, Japanese Patent Publication No. 52-12.
No. 126 publication. In the manufacturing method described in this prior art, the diamond powder is placed in contact with the cemented carbide compact or sintered body, and at a temperature higher than the temperature at which the liquid phase of the cemented carbide is generated and under ultrahigh pressure. And sinter. During sintering, a part of Co in the cemented carbide penetrates into the diamond powder and acts as a binding metal.
By subjecting the diamond sintered body thus obtained to a target shape processing and brazing to various alloys, it is widely used as, for example, a cutting tool, an abrasion resistant tool, an excavating tool, a dresser, and a wire drawing die.

A diamond-coated hard material obtained by coating the surface of a hard material with polycrystalline diamond is also widely used like the above-mentioned diamond sintered body. There are many prior arts, including JP-A-62-57802, JP-A-62-57804, JP-A-62-166904, JP-A-63-14869, and JP-A-63-140084, These have the effect of significantly improving the abrasion resistance of the base material by coating the surface of a hard material of any shape with diamond polycrystal synthesized from the vapor phase. The hard material coated with diamond by this method has a great advantage that it has a high degree of freedom in shape and can be manufactured in large quantities at low cost, and is widely used as, for example, a cutting tool, an abrasion resistant tool, a drilling tool, a dresser, a wire drawing die. There is.

Further, a diamond coating layer is formed on the surface of the base material from the vapor phase, and the base material is removed by etching to manufacture a polycrystalline diamond plate, which is processed into a desired shape and brazed to various base metals. Therefore, it is widely used in the same applications as the above-mentioned two types.

At present, microwave plasma CVD is used as a method for coating the surface of a substrate with polycrystalline diamond from the vapor phase.
Method, RF plasma CVD method, EA-CVD method, induced magnetic field microwave plasma CVD method, RF thermal plasma CVD method,
DC plasma CVD method, DC plasma jet CVD
There are many known methods such as a method, a filament thermal CVD method, a combustion method, etc., and these are powerful methods for producing a diamond coated hard material.

[0007]

By the way, among the above-mentioned conventional techniques, various tools and the like that can be produced by brazing a diamond sintered body to a base metal have a limitation in shape. Specifically, it is difficult with the current technology to braze the diamond sintered body to all blades having a shape such as a 4-flute end mill with excellent accuracy. For this reason, it is necessary to create a round rod-shaped diamond sintered body and obtain the target shape by electrical discharge machining, and the diamond sintered body is used for the parts other than the part that is actually required to improve wear resistance. Therefore, it is very expensive and the productivity is low. Similar to this,
The same can be said when a polycrystalline diamond plate is brazed to a base metal.

In order to overcome the above disadvantages, a diamond-coated hard material in which a diamond coating layer is provided on the surface of a substrate processed into a target shape has been widely developed. Diamond coated hard materials are excellent in various physical properties as a base material.
The use of C-based cemented carbide is considered first, and when it is used as a base material, it has a high degree of freedom in shape and can have a higher strength than that obtained by brazing a diamond sintered body and a polycrystalline diamond plate. It can be fully expected that a large amount can be provided at a lower cost. Therefore, many researchers have attempted to improve its performance, but at present, the adhesion between the diamond coating layer and the substrate is insufficient, and the diamond coating layer often peels off during use, It has not reached the same life as the diamond sintered body. The main causes are (1) thermal compression stress is generated due to the difference in linear expansion coefficient between the base material and diamond, and the diamond coating layer is easily peeled off. (2) Since diamond does not have an intermediate phase with any substance, it has poor wettability with other substances. (3) When the base material contains metal elements such as WC-based cemented carbide and cermet, which facilitates carbon diffusion, such as Fe, Co, and Ni, graphite, which is an isotope of diamond, has priority over these metal elements. The initial nucleation density at the time of coating with diamond is lowered, and thus the adhesion strength between the diamond coating layer and the substrate is lowered. (1) to (3) are listed.

In order to improve (1), a material having the same coefficient of thermal expansion as diamond as a base material, for example, Si
A method of selecting a sintered body containing ₃ N ₄ as a main component or a sintered body containing SiC as a main component has been proposed in Japanese Patent Publication No. 60-59086 and Japanese Patent Application Laid-Open No. 61-291493. Further, in Japanese Patent Application No. 2-269214, a columnar crystal structure of silicon nitride is crystallized on the surface of a base material containing silicon nitride (Si ₃ N ₄ ) as a main component to create a state in which unevenness exists on the surface. A method has been proposed in which a diamond coating layer is provided on this surface to geometrically entangle the diamond coating layer and the substrate to increase the adhesion strength of the diamond coating layer. With these improvements,
The adhesion between the base material and the diamond coating layer was remarkably high. However, when it is applied to a cutting tool, for example, if it is used under severe conditions, the strength of the base material Si ₃ N ₄ or SiC is insufficient, so that the base material is broken and cannot be used. Will increase.

As a solution to (2), Japanese Patent Publication Sho 6
As described in JP 2-7267 A, there is a method of coating the surface of a base material with an intermediate layer and forming a diamond coating layer on this surface. By this method, if a suitable material is selected for the intermediate layer, the diamond coating layer and the intermediate layer can be bonded with high adhesion, but the inventors of the present invention have conducted researches and performed the adhesion under severe conditions. When the force was investigated, it was found that there were 2
At the interface, it has not been possible to find a material for the intermediate layer, which at the same time has sufficient adhesion to withstand use. Further, this method has a drawback that the manufacturing cost is also high.

As a solution to (3), Japanese Unexamined Patent Publication No.
As described in JP-A-2014475, there is a method of etching the surface of a cemented carbide base material with an acid solution to remove metallic elements such as Fe and Co in the binder phase. However, the strength of the base material to be etched itself is lowered, and the dispersed hard phase is likely to be lost due to the removal of the binder phase, so that the diamond coating layer is easily separated together with the hard phase. Further, as described in JP-A-61-124573, a method of improving the initial nucleus generation density of diamond at the time of forming a diamond coating layer by scratching the surface of a substrate with diamond abrasive grains or a grindstone. Has also been devised. However, even with these techniques, sufficient adhesion between the WC-based cemented carbide and the diamond coating layer cannot be obtained,
It has been difficult to obtain a diamond-coated hard material having sufficient adhesion as a cutting tool or wear resistant tool.

As described above, at present, it must be said that the technology for inexpensively mass-producing a diamond coating layer having high adhesion to a cemented carbide substrate is still incomplete. In view of the above problems, the present invention has excellent adhesion strength, high toughness, and
An object of the present invention is to provide a diamond-coated hard material having a high degree of freedom of shape and a manufacturing method thereof.

[0013]

As means for solving the above problems, the present invention provides a diamond-coated hard material comprising a hard material as a base material, and the surface of the base material coated with diamond. There is provided a diamond-coated hard material characterized by the fact that the compressive stress existing therein is smaller than the compressive stress of the surface when the base material is ground, and a method for producing the same. The present invention also provides a diamond-coated hard material comprising a hard material as a base material and a diamond coating layer provided on the surface of the base material, wherein a tensile stress is present on the surface of the base material. A coated hard material is provided. The "compressive stress" referred to in the present invention means "compressive stress remaining on the surface of the base material due to strain caused by grinding or the like". In the present invention, when a WC-based cemented carbide is used as the material for the base material, the compressive stress of the WC phase on the surface of the base material is smaller than that of the ground surface of the base material and / or the compressive stress is less than 0. Those having 5 PGa or less are particularly preferable. Further, the present invention uses a ground WC-based cemented carbide as a base material, and the base material is iron powder, A
After performing blasting treatment with l ₂ O ₃ powder and / or ceramic powder, barrel treatment, heat treatment by quenching, or a combination of these treatments, a diamond coating layer is formed on at least a part of this treated surface. A method for producing a diamond-coated hard material is provided.

[0014]

[Function] Cemented carbide, cermet, Al ₂ O ₃ and Si ₃ N
Machining of various hard materials such as ceramics such as ₄ and SiC is roughly divided into cutting and grinding, and the surface of the base material subjected to these machining is compressed by compression that is considered to be caused by processing strain. There is stress. In order to process WC-based cemented carbide or cermet into the desired shape, 1) electric discharge wire cutter, 2) resin-bonded grindstone, metal-bonded grindstone using diamond and / or boron nitride as abrasive grains, electrodeposition grindstone, , 3) Sintered diamond tools, above 1) ~
3) and the like are used, and in particular, the above 2) is widely used. When WC-based cemented carbide is ground, a compressive stress of about 0.7 to 1.6 GPa occurs in the WC phase on the surface, and the smaller the amount of Co in the cemented carbide, the higher the compressive stress. It has been reported [Reference 1: "Powder and powder metallurgy" Vol. 39, No. 8, p163, Reference 2: "Journal of the Japan Institute of Metals (1975)", Vol. 39, p754].
When forming the diamond coating layer, as described above, it is difficult to generate diamond nuclei on the iron-based metal such as Co.
In general, a low Co cemented carbide is used, but for this reason, the compressive stress of the WC phase at the base material interface is large compared to other cemented carbides.

The reason why the present inventors cannot form a diamond coating layer having good adhesion strength on a WC-based cemented carbide or cermet is that the compressive stress at the base material interface is large. As a result of repeating the test, the compressive stress of the WC phase on the surface of the base material is lower than that after grinding and / or the compressive stress is 0.
Diamond coating with excellent adhesion strength when a diamond coating layer is formed on a WC-based cemented carbide or cermet having a stress of 5 GPa or less, or when a diamond coating layer is formed on a base material in which tensile stress exists Discovered that the layers can be obtained. The compressive stress in the WC phase on the surface of the substrate is, for example, 2θ of the known X-ray diffraction method.
It can be measured by the −sin ² ψ method. The compressive stress can also be measured from the surface after forming the diamond coating layer.

The base material used in the present invention includes cemented carbide, particularly WC-based cemented carbide.
Cermet, Al ₂ O ₃ , Al ₂ O ₃ —TiC, whisker reinforced alumina ceramics, SiC-based ceramics, etc. can also be used. Representative examples of the composition of the cemented carbide as the base material in the present invention are shown below. (1) A WC-based cemented carbide containing 0.5 to 30% by weight of Co as a binder phase component and having a composition of WC and unavoidable impurities as a hard dispersed phase forming component. (2) Co: 0.5 to 30 wt% as a binder phase component, (a) WC as a hard dispersed phase forming component, and (b) Group 4a, 5a and 6a metals of the Periodic Table of Elements excluding W Or their carbides, nitrides, carbonitrides, oxides, borides,
A WC-based cemented carbide having a composition comprising a solid solution of one or more of borocarbide, boronitride, and borocarbonitride, and inevitable impurities. (3) Co: 0.5 to 30% by weight as a binder phase component, (a) WC as a hard dispersed phase forming component, and (b) Group 4a, 5a and 6a metals of the Periodic Table of Elements excluding W Or their carbides, nitrides, carbonitrides, oxides, borides,
A WC-based cemented carbide having a composition comprising a solid solution with one or more of borocarbide, boronitride, borocarbonitride, and (c) WC and inevitable impurities. (4) Co: 0.5 to 30% by weight as a binder phase component, (a) WC as a hard dispersed phase forming component, and (b) Group 4a, 5a and 6a metals of the Periodic Table of Elements excluding W Or their carbides, nitrides, carbonitrides, oxides, borides,
Solid solution with one or more of borocarbide, boronitride, borocarbonitride, and (c) WC, and / or (d) WC and group 4a, 5a and 6a metals of the Periodic Table of Elements excluding W or One of these carbides, nitrides, carbonitrides, oxides, borides, borocarbides, boronitrides, borocarbonitrides
A WC-based cemented carbide having a composition of at least one solid solution and inevitable impurities (excluding those overlapping with (3)). Note that the above composition is shown in a general range, and the meaning to be particularly limited is that the balance between the hard dispersed phase and the binder phase is good in these ranges, and the high strength of the base material can be maintained. .

As a method for reducing the compressive stress existing on the surface of the hard material substrate, the following methods can be mentioned, for example. That is, as a method of reducing the compressive stress of the base material after the grinding process, blasting in which iron powder, alumina powder, or GC abrasive grains (SiC abrasive grains exhibiting a green color with high purity) are sprayed on the base material after the grinding process. Treatment, barrel treatment that gives rotation or vibration in the container together with the abrasive grains,
Alternatively, the residual stress on the surface can be reduced by up to 70% by quenching, for example, by subjecting the substrate to a thermal shock by cooling from the room temperature to the liquid nitrogen temperature, or a combination of these treatments. Became.

Further, the method of annealing the base material after grinding in a non-oxidizing atmosphere is also an effective method for removing the WC phase compressive stress. The relationship between the annealing temperature and the compressive stress in the WC phase at this time is as described in Journal of Japan Institute of Metals (1985) Vol. If the alloy is annealed near the sintering temperature, its compressive stress becomes almost zero. However, depending on the annealing conditions, an iron-based metal such as Co that is a binder phase leaches or leaches on the surface of the base material due to the annealing, so that 4A of the Periodic Table of Elements excluding W as a hard phase component in the base material, Carbides, nitrides, carbonitrides, oxides, borides, borocarbides, boronitrides, borocarbonitrides of Group 5A and 6A metals and two or more solid solutions containing these WCs (hereinafter referred to as β phase) Including CO gas and / or N
_When sintered in a _two- gas atmosphere, a mass transfer to the β-phase interface occurs during annealing, so that there is no binder phase on the substrate surface at the end of annealing. Therefore, when the diamond coating layer is formed on this annealed base material, the diamond nucleus generation density at the initial stage of diamond coating becomes high, which can be expected to contribute to the improvement of the adhesion between the diamond coating layer and the base material. When the β phase is excessively moved to the interface by the above method, tensile stress is generated on the surface of the base material.

A diamond layer is formed on the surface of the substrate whose surface compressive stress has been reduced as described above. At this time, any of the known diamond coating forming means described above can be adopted.

Further, the layer thickness of the diamond coating layer may be a layer thickness necessary for each application. However, in applications where wear resistance is required, if the layer thickness is less than 0.5 μm, improvement in various properties such as wear resistance due to the coating layer is not recognized, so wear resistance of cutting tools, wear tools, etc. In use applications where is required, a layer thickness of 0.5 μm or more is preferable. Further, even when a coating layer having a thickness of more than 500 μm is formed, a large improvement in abrasion resistance is no longer recognized. Therefore, when the coating layer is used for the above-mentioned use, 0.5 μm to 500 μm is desirable for economic reasons.

Up to this point, the explanation has been centered on the diamond coating layer, but the present invention also has exactly the same effect when coating diamond-like carbon and multiple layers thereof. Furthermore, the same applies when these coating layers contain boron and nitrogen. Further, as the diamond coating method, any method known in this field can be used, including the methods described in the prior art.

Even if the surface of the diamond coating layer is smoothed or mirror-finished by a grindstone or heat treatment in order to obtain a predetermined surface roughness and / or dimensional accuracy, the superiority of the present invention is not impaired.

[0023]

EXAMPLES Next, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. [Example 1] As a base material, the raw material powders shown in Table 1 were crushed using a vibration mill, and a material to which a binder was added was press-molded and molded, and after debinding at 300 ° C, at 1400 ° C. 1 in 100 Torr N ₂ atmosphere
Time sintering was performed to obtain a sintered body substrate. Further, a grinding base material was also prepared by grinding the surface of the obtained sintered body base material with a # 280 resin bond diamond grindstone.

[0024]

[Table 1]

The compressive stress of the WC phase on the surface of these base materials is Cr-K by a known X-ray diffraction method (2θ-sin ² ψ method).
As a result of measurement using α ray, only a compressive stress of 0.2 GPa or less remained on the surface of each sintered body, but a compressive stress of 1.0 GPa or more was present on each ground surface. Was. These base materials are 2.45 GHz
Hydrogen-methane 2.5 heated to 900 ° C. and total pressure of 80 Torr using the microwave plasma CVD apparatus of
% Mixed plasma for 8 hours to form a diamond coating layer having a layer thickness of 10 μm. When the compressive stress of these diamond-coated hard materials was measured, it was 0.4 GPa or less for all the diamond-coated hard material with the diamond coating layer formed on the surface thereof, whereas the diamond-coated hard material was Also, the compressive stress exceeding 0.5 GPa remained. In order to compare the adhesion between these diamond-coated hard materials and the diamond-coated layer, the indenter was pressed for 30 seconds with a load of 60 kg using a Rockwell indenter / A scale, which caused the diamond-coated layer to peel off. Comparing the areas, the sintered body substrate having the same composition has a peeled area of 20 to 80 as compared with the ground substrate.
% And decreased.

Example 2 As a base material, the raw material powders shown in Table 2 were crushed using a vibration mill, and a material to which a binder was added was press-molded, debindered at 300 ° C., and then de-bindered at 1400 ° C. Sintering is performed for 1 hour in a vacuum, and the resulting sintered body is ground with a # 280 resin-bonded diamond grindstone to give a shape of inscribed circle: 1
2.7 mm, thickness: 3.18 mm, corner R: 0.8
mm, clearance angle: 20 ° JIS B4103 SEGN
A 422-shaped WC-based cemented carbide throw-away tip was manufactured. The compressive stress on the surface of these chips is as shown in Table 2. Table 3 for these base material chips
By performing the surface treatment shown in, the compressive stress due to the grinding process of the WC phase was reduced. With respect to these base material chips, a diamond coating layer was formed under the conditions shown in Table 4 below by using a known thermal filament CVD method, and the diamond coated throwaway chips No. 1 to No. 13 of the present invention were formed.
Was manufactured. The diamond coating layer thickness of each chip is also shown in Table 3. In the tip of the present invention No. 10, the surface of the diamond coating layer was smoothed to 0.5 S near the cutting edge with a diamond brush.

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

In this example, the coating layer deposited on the surface of the substrate was confirmed by Raman spectroscopy to have a peak at 1333 cm ^-1 which is a characteristic of diamond. For comparison, comparative chips A to C of the same shape in which a diamond coating layer is formed on a base material chip not subjected to surface treatment, comparative chips D to E not subjected to surface treatment or diamond coating layer formation, Polycrystalline diamond of 0.3 mm having virtually no binder phase produced by coating the surface of a Si substrate with diamond for 200 hours under the same conditions as in the hot filament CVD method described above, and then etching away the substrate with acid. Carbide base metal (e composition in Table 2)
A diamond sintered compact chip (comparative chip F) of the same shape manufactured by brazing and grinding on a commercially available binder phase
A cemented carbide base metal (Table 2
Of the same shape), and a glass sintered compact chip of the same shape (comparative chip G) manufactured by brazing and a chip having the same shape of Si ₃ N ₄ -3Al ₂ O ₃ -5ZrO ₂ The substrate was prepared and kept at 1800 ° C. and 5 atm for 1 hour, and the same as above was applied to a substrate on which free-grown Si ₃ N ₄ columnar crystals having a major axis of 8 μm and a minor axis of 1.5 μm were deposited on the surface. A silicon nitride ceramic substrate diamond-coated cutting tip (comparative tip H) having a diamond coating layer formed by the method was also prepared.

Using these cutting tips, cutting was performed under the two conditions shown in Table 5 below, and the flank wear amount and the wear state of the cutting edge were observed in the continuous cutting test, and 16 corners in the intermittent cutting test. Was cut, and the number of missing cutting edges was counted. The results are also shown in Table 6.

[0032]

[Table 5]

[0033]

[Table 6]

From these results, it can be seen that the diamond coating layer on the surface of the sintered surface of the chip of the present invention has excellent adhesion strength. Further, in the chip of the present invention, a tough cemented carbide is used as the base material, and it is understood that the chip has higher toughness as compared with a brazing tool for a diamond sintered body or a polycrystalline diamond plate. Further, when the compressive stress of the WC phase on the surface of the base material was measured from the surface of the diamond coating layer after the diamond coating layer was formed, for example, in the case of the chip No. 6 of the present invention, it was 0.
3 GPa, 0.1 GPa for the chip No. 7 of the present invention
It was confirmed that the following compressive stress exists. In addition, a carbide tip without a diamond layer (comparative tip A ~
In C), while the work material is welded to the cutting edge to form the constituent cutting edge, the cutting resistance is improved and the chip is easily broken, whereas
According to the present invention, such a tendency can be greatly reduced.

[0035]

EFFECTS OF THE INVENTION The diamond-coated hard material of the present invention has good diamond film releasability as compared with conventional diamond-coated hard materials, and is equivalent to natural diamond, sintered diamond, and polycrystalline diamond. It is clear that it has abrasion resistance and has a hard strength. Further, according to the manufacturing method of the present invention, compared with the case of using a natural diamond, a diamond sintered body, a polycrystalline diamond, etc., it has an advantage that it has a high degree of freedom in shape and can be manufactured inexpensively in a large amount. There is. Further, in the above-mentioned embodiment, the case of the cutting tool was mentioned, but also when applied to various cutting tools, abrasion resistant tools, various machine parts, grindstones, various jigs, corrosion resistant materials, etc., good results can be obtained. That is quite predictable.

Claims (5)

[Claims] 1. A diamond-coated hard material comprising a hard material as a base material, and the surface of the base material coated with diamond, wherein the compressive stress present on the surface of the base material is the surface when the base material is ground. The diamond-coated hard material is characterized by being smaller than the compressive stress of. 2. A diamond-coated hard material comprising a base material of WC-based cemented carbide and a diamond coating layer provided on at least a part of the surface of the base material, wherein the WC phase on the surface of the base material coated with the diamond. Is lower than the compressive stress of the WC phase of the surface when the surface of the substrate is ground with a grindstone. 3. A diamond-coated hard material comprising a base material of WC-based cemented carbide and having a diamond coating layer provided on at least a part of the surface of the base material, wherein the WC phase on the surface of the base material coated with the diamond. Compressive stress of 0.5
A diamond-coated hard material having a GPa or lower. 4. A diamond-coated hard material comprising a hard material as a base material and a diamond coating layer provided on the base material surface, wherein a tensile stress is present on the base material surface. Coated hard material. 5. A grounded WC-based cemented carbide is used as a base material, and the base is blasted with iron powder, Al ₂ O ₃ powder and / or ceramic powder, barrel treatment, heat treatment by quenching, Alternatively, a method for producing a diamond-coated hard material, which comprises performing a combination treatment of these treatments and then forming a diamond coating layer on at least a part of the treated surface.