JPH04263075A - Diamond or diamondlike carbon-coated hard material - Google Patents

Abstract

PURPOSE:To improve peeling resistance by forming specified microscopic ruggednesses on the surface of a hard substrate and enhancing the adhesive strength of an interface between a diamond-based coating layer and the substrate. CONSTITUTION:Microscopic ruggednesses are formed on the surface of a substrate consisting of a hard material (cemented carbide, cermet, Al2O3, silicon nitride and silicon carbide). One or more protrusions of the substrate are formed at the interface between the substrate and the diamond and/or diamondlike carbon (diamond-based coating layer) for each sampling length of 10mum, the ratio of the sum A of the lengths of the recesses to the sum B of the lengths of protrusions is controlled to 0.05-20 in the sampling length at the interface, and the protrusions are allowed to intrude into the diamond-based coating layer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond-coated hard material having a diamond or diamond-like carbon coating layer having high adhesion strength to a base material.

0002

[Prior Art] Diamond has many excellent properties, including extremely high hardness, chemical stability, high thermal conductivity, and high acoustic propagation speed. Alternatively, as hard materials coated with diamond or diamond-like carbon, for example, the following are widely used in practical use. ■ Single-crystal diamond, sintered diamond, or diamond coating, which hardly reacts with Al, Cu, and various light metals used in practical use, or their alloys, allows these alloys to be cut at high speed and with an extremely good surface finish. Cutting tools, such as indexable inserts, drills, micro drills, end mills, etc. ■ Various wear-resistant tools such as bonding tools that have high wear resistance and enable long-term machining with high dimensional accuracy. ■ Various mechanical parts including heat sinks. ■ Various types of diaphragms including speakers. ■ Various electronic components.

Among the methods for producing artificial diamonds, methods for forming a diamond coating layer from a gas phase include the μ-wave plasma CVD method, the RF-plasma CVD method, and the E-plasma CVD method.
Many methods are known, including the A-CVD method, magnetic field μ-wave plasma CVD method, RF thermal plasma CVD method, DC plasma CVD method, DC plasma jet CVD method, filament thermal CVD method, and combustion method. It is a powerful method of material production.

0004

However, in most diamond-coated hard materials, the adhesion strength between the base material and the diamond coating layer is insufficient, so that the diamond coating layer often peels off, leading to the end of its life. A major reason for this is thought to be that diamond has poor wettability with other substances because it does not have an intermediate layer with any substance. In order to obtain a diamond-coated hard material with high adhesion strength, a method of selecting a base material with the same coefficient of thermal expansion as diamond (Japanese Patent Publication No. 61-291493,
3 N4 as the main component and SiC as the main component), and metals that have a negative effect on the formation of the diamond coating layer on the surface of the substrate are removed by etching, and the substrate is A method of increasing the density of diamond nuclei on the surface (in Japanese Patent Application Laid-Open No. 1-201475, the surface of the cemented carbide is etched with an acid solution to remove the Co metal component,
In Japanese Patent Application Laid-Open No. 61-124573, the surface of the base material is scratched using diamond abrasive grains or a grindstone to increase the density of diamond nuclei generated on the surface of the base material. However, the adhesion strength is currently insufficient. The present invention aims to solve these problems and provide a diamond-coated hard material with excellent adhesion strength.

[0005]

[Means for Solving the Problem] As mentioned above, diamond is extremely chemically stable and does not form intermediate compounds with any substances. Therefore, when producing a diamond-coated hard material with excellent adhesion strength, it is necessary to create a state in which the diamond coating layer and the base material are joined by some strong physical force. In order to achieve this, the present inventor created a state in which convex parts are mechanically or chemically created on the surface of the base material and have high adhesion strength to the base material, and the surface of this base material is coated with diamond. It has been discovered that when a diamond coating layer is formed and the convex portions penetrate into the diamond coating layer, the adhesion strength between the diamond coating layer and the base material becomes extremely high. This is thought to be because the contact area between the diamond coating layer and the base material increased, and the convex portions had an anchoring effect for the diamond coating layer, making it difficult for the diamond coating layer to peel off.

The unevenness described here is not a macroscopic unevenness formed by (1) a diamond grinding wheel, (2) scratching treatment with diamond abrasive grains, etc., but is an unevenness within a minute section, and is a diamond coating layer. - At the base material interface, the reference length is a minute section such as 10 μm, and it refers to unevenness within this reference length. As a result of creating various uneven states, the present inventors found that 10 μm
There is at least one convex portion within the standard length of
and within the standard length, the ratio of the total length B of the convex portions to the total length A of the concave portions is 0.05≦A/B≦20, and the convex portions are included in the diamond coating layer. It was discovered that the adhesion strength increases when the penetration depth is 0.2 μm or more. This was calculated by lapping the cross section of the substrate after diamond coating, observing and photographing it, and schematizing the interface between the diamond coating layer and the substrate.

[0007] At the initial stage of coating, in order to promote the generation of diamond nuclei over the entire chip surface, it is desirable to carry out a commonly used scratching process using diamond abrasive grains. At this time, if the abrasive grains are physically pressed and scratched, there is a possibility that the protrusions that have been created may be chipped or destroyed. It is preferable to perform damage treatment by throwing the liquid into a solution and applying ultrasonic vibration to the solution. By this scratching treatment, diamond nuclei are generated evenly over the entire convex and non-convex portions of the surface of the base material. This made it possible to create a state in which the convex portion penetrated into the diamond coating layer.

[0008] As a specific method for creating unevenness on the base material,
A method for depositing columnar crystals and/or needle crystals on the surface of a substrate ■ A method for removing binders that are easily etched by etching ■ A method for applying a mask to the substrate, etching, and then removing the mask ■ Physics using lasers, etc. Select an appropriate method depending on the base material, such as a method using mechanical processing. Method (2) involves subjecting the base material to some kind of heat treatment to allow the free growth of columnar crystals or needle-shaped crystals from the base material components on the surface and/or promoting the generation of secondary crystals. This method is effective for materials composed of a hard phase and a binder phase that have different corrosivity to alkali. Method (2) is a method in which a photomask is used to provide a mask in an arbitrary pattern, and then the mask is removed by etching.

Materials constituting the convex portion include silicon nitride crystals, crystals containing silicon nitride, sialon, silicon carbide, substances containing silicon carbide, tungsten, carbides or carbonitrides of tungsten, tungsten and one other type, or 2
Selected from the group consisting of carbides or carbonitrides of at least one metal, and substances containing these. Here, Sialon (
Sialon) is a silicon nitride crystal in which part of Si and N are replaced with Al and O, respectively, and includes α-sialon and β-sialon. It is preferable that the substance forming these uneven portions is integral with the base material and made of the same material, and the same material may have a different composition.

FIG. 1 schematically shows the state of the diamond and/or diamond-like carbon coating layer-substrate interface according to the present invention. Here, the sum of the lengths of the convex portions A, that is, ΣA, and the sum of the lengths of the concave portions, B, that is, ΣB
The ratio H0.05≦ΣA/ΣB≦20,
The penetration length of the convex portion is preferably 0.2 μm or more. For example, when there is one convex portion of 0.5 μm in 10 μm, ΣA/ΣB=19.

In any case, the convex portions formed in this manner have a reference length of 10 μm at the diamond and/or diamond-like carbon coating layer-substrate interface.
Then, within this standard length, there is at least one location, and the total length of the convex portion B and the total length of the concave portion A
It is necessary that the ratio is in the range of 0.05 or more and 20 or less, and the convex portion must penetrate into the diamond coating layer. In this case, the penetration length is preferably 0.2 μm or more. If the ratio of the total length B of the convex portions to the total length A of the concave portions deviates from the range of 0.05≦A/B≦20, no improvement in adhesion strength is observed.

[0012] The base material is cemented carbide, cermet, Al2
Any hard material can be used, including various ceramics such as O3, silicon nitride, and silicon carbide. In this,
In particular, silicon nitride, silicon carbide, titanium carbide, titanium nitride,
Compounds of Ti such as titanium carbonitride and/or Ti
It has also been found that high adhesion strength is exhibited when there are irregularities caused by a substance containing a compound of tungsten carbide and/or a tungsten alloy carbide and/or a substance containing these. Furthermore, the shape of the convex portion has an aspect ratio of 1.
．． It was also found that the adhesion strength becomes even higher when the crystals are columnar crystals of 5 or more or when they are needle crystals.

[0013] Regarding the thickness of the diamond coating layer, if the thickness is less than 0.1 μm, no improvement in various performances such as wear resistance is observed due to the coating layer, and even if the coating layer is formed with a thickness of 200 μm or more, the performance is no longer significant. 0.1 μm to 200 μm is desirable.

[0014] The above explanation has been made regarding the case where diamond is coated, but when diamond-like carbon is mixed in the diamond coating layer, when it is composed of a single layer or two or more layers of these, and when this coating layer is Exactly the same effect can be obtained when a different type of atom such as boron or nitrogen is included. The same applies to the case where diamond-like carbon is coated, and the excellent effects of the present invention can be achieved. Next, the present invention will be specifically explained using examples.

[0015]

[Example] Example 1 A silicon nitride-based ceramic (specifically, Si
3 N4 -4wt%Al2 O3 -4wt%ZrO
A throw-away tip with a shape of SPG422 was prepared using 2-3 wt% Y2O3). This chip, 180
When heat-treated for 40 minutes at 0°C and 5 atm N2 gas atmosphere, the chip surface had a short axis of 2 μm and a long axis of 8
Columnar crystals and needle-like crystals of silicon nitride with an aspect ratio of 4 μm were generated. 2g of this chip with a particle size of 8 to 16μ
The sample was placed in ethyl alcohol together with diamond abrasive grains of 1.0 m, and subjected to ultrasonic vibration for 15 minutes. The chip produced in this way was subjected to 2.45 GHz μ-wave plasma CVD.
Using a device, heat to 1000°C and raise the total pressure to 80 Torr.
A diamond-coated cutting tip with a layer thickness of 10 μm was prepared by holding the sample in a hydrogen-methane mixed plasma of 2% at r for 8 hours. In addition, for comparison, we prepared a comparative chip with a diamond coating layer on a chip with the same shape and composition but no silicon nitride columnar crystals on the surface because no heat treatment was performed (the comparative chip was treated with ultrasonic was not carried out). In this test, the coating layer deposited on the surface of the base material was confirmed to be a diamond coating layer by Raman spectroscopy.

[0016] Using these cutting tips, the workpiece material
: Al-24wt%Si alloy (block material) Cutting speed: 400m/min Feed: 0.1mm/rev. depth of cut
: Intermittent cutting was performed under the condition of 0.5 mm, and the amount of flank wear, the wear state of the cutting edge, and the welding state of the workpiece material were observed after 3 minutes and 10 minutes. When the cutting edge was observed 10 minutes after the start, the amount of flank wear was 0.04 mm, indicating normal wear, and almost no welding of the work material was observed. On the other hand, with the comparison insert, when observing the cutting edge 3 minutes after the start of cutting, large peeling of the diamond coating layer was observed, the amount of flank wear was 0.11 mm, and the workpiece material was also largely welded, so cutting has been discontinued.

After cutting and lapping the chip after the cutting test, the interface between the base material and the diamond coating layer was observed using an optical microscope, and it was found that in the cutting chip of the present invention, the columnar crystals of silicon nitride were present in the diamond coating layer with a maximum thickness of 3 μm. It was confirmed that 3 to 5 convex portions were present within the standard length of 10 μm, and A/B was 0.7 to 1.2. In the comparative chip, no columnar crystals of silicon nitride were present at the interface between the base material and the diamond coating layer, and no intrusion of the base material into the diamond coating layer was observed.

Example 2 Silicon carbide whisker ceramic (specifically, Al2O3-35vol%SiC whisker 5w) was used as the base material.
A throw-away chip with a shape of SPG422 was manufactured using t%ZrO2). By bringing this chip into contact with molten NaOH and etching it, needle-like crystals of silicon carbide whiskers with a short axis of 1 μm and a long axis of 8 μm were exposed on the chip surface. 2g of this chip has a particle size of 8 to 16 μm.
The sample was placed in ethyl alcohol together with diamond abrasive grains, and ultrasonic vibration was applied for 15 minutes. The chip thus produced was heated to 1000°C using a 2.45GHz μ-wave plasma CVD device, and the total pressure was adjusted to 80 Torr.
A diamond-coated cutting tip with a layer thickness of 9 μm was prepared by holding the sample in a 2% hydrogen-methane mixed plasma for 7 hours. In addition, for comparison, we prepared a comparison chip in which a diamond coating layer was provided on a chip with the same shape and composition and no acicular crystals of silicon carbide whiskers on the surface because no etching treatment was performed. (No ultrasound treatment was performed). In this test, the coating layer deposited on the surface of the base material was confirmed to be a diamond coating layer by Raman spectroscopy.

[0019] Using these cutting tips, the workpiece material
: Al-24wt%Si alloy (block material) Cutting speed: 400m/min Feed: 0.1mm/rev. depth of cut
: Intermittent cutting was performed under the condition of 0.5 mm, and the amount of flank wear, the wear state of the cutting blade, and the welding state of the workpiece material were observed after 3 minutes and 10 minutes. When the cutting edge was observed 10 minutes after the start, the amount of flank wear was 0.05 mm, indicating normal wear, and almost no welding of the work material was observed. On the other hand, with the comparison insert, when observing the cutting edge 3 minutes after the start of cutting, large peeling of the diamond coating layer was observed, the amount of flank wear was 0.14 mm, and the workpiece material was also largely welded, resulting in cutting. has been discontinued.

After cutting and lapping the chip after the cutting test, the interface between the base material and the diamond coating layer was observed using an optical microscope, and it was found that in the cutting chip of the present invention, the silicon carbide whiskers were at the maximum depth of 4 μm in the diamond coating layer. At the interface, within the standard length of 10 μm, 3~
It was confirmed that 6 convex portions were present and A/B was 1.0 to 1.6. In addition, in the comparison chip, the base material -
No silicon carbide whiskers were present at the diamond coating layer interface, and no intrusion of the base material into the diamond coating layer was observed.

Example 3 JIS-K10 cemented carbide (specifically WC) was used as the base material.
A throw-away tip with a shape of SPG422 was manufactured using -5% Co). After mirror-finishing this chip, a groove of 3.0 μm in depth and 1.5 μm in width was created by laser processing.
Machining into a lattice shape with a spacing of 3.0 m (2) Grooves 3.0 μm deep and 3.0 μm wide
(3) Grooves with a depth of 0.2 μm and a width of 1.5 μm
(4) Grooves with a depth of 3.0 μm and a width of 2.0 μm are cut into 8 μm grooves.
Chips (1) to (4) of the present invention processed into a lattice shape with m spacing were fabricated. A/B is 1.75, 1.33, and 0.25, respectively. In the same manner as above, this chip was poured into ethyl alcohol along with 2 g of diamond abrasive grains with a particle size of 8 to 16 μm,
Ultrasonic vibration was applied for 15 minutes. Using a known hot filament CVD method on the surface of the chip produced in this way, a reaction tube container was formed.
: Quartz tube with a diameter of 200mm
Filament material:
Metal W filament temperature
: 2400℃ Distance between filament and chip surface: 7.0mm
total pressure
: 100Torr Atmosphere gas: H2
-1.5%CH4 gas time
: A diamond coating layer of 6 μm was formed under conditions of 7 hours. For comparison, a comparison chip was prepared in which a diamond coating layer was provided on a chip with the same shape and composition that was not subjected to laser processing (the comparison chip was not subjected to ultrasonic treatment). In this test, the coating layer deposited on the surface of the base material was confirmed to be a diamond coating layer by Raman spectroscopy.

[0022] Using these cutting tips, the workpiece material
: Al-12wt%Si alloy (round bar) Cutting speed: 1000m/min Feed:
0.15mm/rev. Depth of cut: 1.5m
Intermittent cutting was carried out under the conditions of 1.m, and the amount of flank wear, the wear state of the cutting edge, and the welding state of the workpiece material were observed after 5 and 30 minutes.Cutting chips of the present invention (1) to (4) ), the amount of flank wear was 0.03, 0.02, 0.08, and 0.07 mm, respectively, when observing the cutting edge 10 minutes after the start of cutting.
The wear was normal, and there was almost no welding of the work material. On the other hand, with the comparative chip, cutting starts at 5
When observing the cutting edge after 30 minutes, large peeling of the diamond coating layer was observed, and the amount of flank wear was 0.23 mm.
Cutting was stopped because the workpiece material was also heavily welded.

After cutting and lapping the chip after the cutting test, the interface between the base material and the diamond coating layer was observed using an optical microscope. It was confirmed that the penetration was at a depth of 3 μm, and that A/B was the expected value. In the comparison chip, no intrusion of the base material into the diamond coating layer and no unevenness were observed.

[0024]

The hard materials coated with diamond and/or diamond-like carbon of the present invention are found to have better peeling resistance than the conventional hard materials coated with diamond and/or diamond-like carbon. The methods in Examples 1 and 2 are surface treatments that take advantage of the characteristics of the base material, but the method in Example 3 has excellent applicability regardless of the base material.
Good results can also be obtained when the base material is made of various ceramics, cermets, etc. mainly composed of Al2O3. Furthermore, although this example introduced the case of cutting tools, good results were also obtained when applied to wear-resistant tools such as TAB tools and machine parts. In addition, it can be applied to end mills, drills, printed circuit board drilling drills, reamers, etc.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram schematically showing the state of the coating layer-substrate interface of the present invention.

Claims (10)

[Claims] Claim 1: In a coated hard material formed by forming a diamond and/or diamond-like carbon coating layer on the surface of a hard material, (1) microscopic irregularities exist on the surface of the base material, and (2) convex portions are present. exists at least one location within the standard length at the diamond and/or diamond-like carbon coating layer-substrate interface when the standard length is 10 μm, and (3) within the standard length at the interface, The ratio of the total length B of the convex portions to the total length A of the concave portions is 0.05≦A/B≦20, (4) and the convex portions penetrate into the diamond coating layer. , a diamond or diamond-like carbon coated hard material. 2. The diamond and/or diamond-like carbon coating layer has convexities of at least 0.2 μm.
Diamond or diamond-like carbon-coated hard material according to claim 1, characterized in that it is intruded. 3. The diamond or diamond-like carbon-coated hard material according to claim 1, wherein the convex portion is a silicon nitride crystal and/or a crystal containing silicon nitride and/or a sialon. 4. Claim 1, wherein the convex portion is made of silicon carbide and/or a substance containing silicon carbide.
or the diamond- or diamond-like carbon-coated hard material described in 2. [Claim 5] The convex portion is (1) tungsten, (2)
Consists of one or more materials selected from the group consisting of tungsten carbide or carbonitride, (3) carbide or carbonitride of tungsten and one or more other metals, and (4) substances containing these. The diamond- or diamond-like carbon-coated hard material according to claim 1 or 2, characterized in that the diamond- or diamond-like carbon-coated hard material is coated with diamond or diamond-like carbon. 6. The diamond or diamond-like carbon-coated hard material according to claim 1, wherein the invading substance has a columnar shape with an aspect ratio of 1.5 or more. 7. The diamond or diamond-like carbon-coated hard material according to claim 1, wherein the shape of the invading substance is acicular. [Claim 8] The hard material is (1) cemented carbide, (2)
The diamond or diamond-like carbon coating according to any one of claims 1 to 7, characterized in that it is a cermet, (3) various ceramics such as Al2O3, silicon nitride, and silicon carbide, or (4) a composite material thereof. Hard material. 9. Any one of claims 1 to 8, wherein the substance forming the uneven portion at the boundary between the diamond or diamond-like carbon coating layer and the base material is the same material as the base material. Diamond or diamond-like carbon coated hard materials as described in . 10. A claim characterized in that the substance forming the uneven portion at the boundary between the diamond or diamond-like carbon coating layer and the base material is the same material as the base material but has a different composition. Item 9. Diamond or diamond-like carbon-coated hard material according to any one of Items 1 to 8.