JP2964669B2 - Boron nitride coated hard material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boron nitride coated hard material having a boron nitride coating layer having high adhesion strength to a substrate.

[0002]

2. Description of the Related Art Boron nitride (BN) is known to have a crystal structure such as hexagonal boron nitride and cubic boron nitride (hereinafter also referred to as CBN), of which CBN has a room temperature hardness next to diamond. It is also known that they are stable at higher temperatures and have higher strength than diamond. For this reason, when CBN or a coating layer containing CBN is coated on the surface of a cutting tool, a wear-resistant tool, or other mechanical parts, good wear resistance can be expected. In particular, rolls, guide rollers, where the workpiece and work material are steel and cast iron,
When used as a coating layer on the surface of a wear-resistant tool such as a seal ring, a rocker arm tip, a nozzle, a die, a die, or the like, or a cutting tool, good wear resistance can be expected. Actually, cutting tools and wear-resistant tools in which CBN is joined with metal or ceramic have been put to practical use.

[0003] Among the methods for producing artificial boron nitride,
As a method for forming a boron nitride coating layer from a gas phase, various methods such as a plasma CVD method, an ion plating method, a sputtering method, and an ion beam assisted vacuum deposition method are known. It is a way.

[0004]

However, most of the boron nitride-coated hard materials have insufficient adhesion strength between the substrate and the boron nitride coating layer, and thus are particularly applicable to use under severe conditions such as cutting tools. In such a case, the boron nitride coating layer is often peeled off to reach the end of its life. A major cause of this is considered to be that it does not have an intermediate phase with other substances. Many attempts have been made to provide an intermediate layer between a substrate and a boron nitride coating layer in order to obtain a boron nitride-coated hard material having high adhesion strength (for example, Japanese Patent Application Laid-Open No. 60-204687, JP-A-63-20446, JP-A-63-35774, JP-A-63-2
39103 publication). However, a boron nitride coating layer having good adhesion strength has not yet been realized. Also, Ar
And processing the substrate in the plasma, such as H _2, a method of removing impurities from the surface, ensuring the adhesion strength between the base material by depositing a boron nitride coating layer on the thus obtained were cleaned on the surface Proposed. However, even with this method, sufficient adhesion strength has not been obtained. An object of the present invention is to solve these problems and to provide a boron nitride-coated hard material having excellent adhesion strength.

[0005]

The present invention relates to a coated hard material comprising a hard material and a boron nitride coating layer formed on the surface thereof, wherein at least one intermediate layer is provided between the substrate surface and the boron nitride coating layer. Exists, and the surface roughness of the intermediate layer re-surface is 0.1 at Rmax.
An object of the present invention is to provide a boron nitride-coated hard material having a thickness of 5 μm or more. Further, the present invention provides a coated hard material obtained by forming a boron nitride coating layer on the surface of a hard material, wherein one or more intermediate layers exist between the substrate surface and the boron nitride coating layer. (2)
The present invention provides a boron nitride-coated hard material characterized in that the surface roughness within this reference length is 0.5 to 30 μm when the reference length is 50 μm.

[0006] As mentioned above, boron nitride is extremely chemically stable and does not form intermediates with any substance. For this reason, when producing a boron nitride-coated hard material having excellent adhesion strength, it is necessary to create a state in which the boron nitride coating layer and the base material are joined by some physical strong force. The present inventor has realized that
At least one intermediate layer having high adhesion strength to the substrate and good wettability with boron nitride is provided on the surface of the substrate, and the surface roughness of the outermost surface of the intermediate layer is (1) macroscopically, If the surface roughness is 0.5 μm or more in Rmax, and / or (2) microscopic unevenness is present, the reference length at the interface between the intermediate layer and the boron nitride coating layer is set to 50 μm. When the surface roughness of Rmax is 0.5 μm to 30 μm at Rmax and the projections are in a state of penetrating into the boron nitride coating,
It has been found that the physical desorption force of the boron nitride coating layer is increased, and the adhesion strength between the boron nitride coating layer and the base material is very high. This is because the intermediate layer and the base material are first selected to be chemically or / and mechanically bonded, resulting in very high adhesion strength. Further, the contact area between the boron nitride coating layer and the intermediate layer is increased by making the surface rough, and has a high physical adhesion strength. Further, it is considered that the minute unevenness has an anchoring effect of the boron nitride coating layer, and the boron nitride coating layer is hardly peeled off.

The surface roughness described here means (1) diamond grinding stone, (2) damage treatment by diamond abrasive grains,
This includes not only macroscopic surface roughness that can be measured by a surface roughness meter formed by the method described above, but also surface roughness due to the presence of unevenness in a minute section. The surface roughness in the minute section refers to the surface roughness in the minute section such as a reference length of 50 μm at the interface between the boron nitride coating layer and the outermost surface of the intermediate layer. The present inventors have created various surface roughness states, and as a result, within a reference length of 50 μm, the surface roughness at the substrate interface is 0.5 to 30 at Rmax.
It was discovered that the state of μm increased the adhesion strength. The outermost surface roughness can be measured by lapping the cross section of the substrate after the boron nitride coating, observing the photograph, taking a photograph, and using the boundary line of the interface between the boron nitride coating layer and the outermost surface of the intermediate layer as the base surface after the coating. The surface roughness (Rmax) of the material. However, at this time, the macroscopic undulation is calculated by linear approximation.

FIG. 1 schematically shows the state of the interface between the boron nitride coating layer and the intermediate layer according to the present invention. That is, although macroscopic undulation is recognized at the interface, this is regarded as a pseudo straight line as shown in FIG. 2 and Rmax is calculated.

[0009] As a specific method for roughening the surface to be coated with boron nitride, there is a method of coating a substance which becomes a columnar crystal and / or a needle-like crystal on the surface of the intermediate layer or a substance containing these. The intermediate layer surface is roughened by etching. The outermost surface of the intermediate layer is masked and then etched.
Subsequent removal of the mask Method of physical processing with a laser, brush, grindstone, etc. Method of coating coarse particles on a part of the base material Substrate such as providing parts to be coated and parts not to be coated on the surface of the substrate Select an appropriate method according to. The method is
This is a method in which the outermost surface of the intermediate layer is processed by a resin-bonded grindstone, a metal-bonded grindstone, an electrodeposition grindstone using diamond or BN abrasive grains, and a rough surface as shown in FIG. 3 is obtained, for example. Is a commonly used CVD method, plasma C
This is a method in which needle-like and / or columnar crystals such as silicon nitride, silicon carbide, and aluminum oxide are precipitated on the outermost surface of the intermediate layer by VD, RFCVD, or the like. can get. Is a method in which a carbide, nitride, carbonitride or the like of titanium is used as an outermost surface and etched with an acid such as aqua regia to make the surface rough. For example, a rough surface as shown in FIG. 5 is obtained. . Is a method of providing a mask in an arbitrary pattern using a photomask, and then removing the mask by etching or the like.
For example, a rough surface as shown in FIG. 6 is obtained. In FIG. 6, the flat portion on the outermost surface of the intermediate layer is a portion that has been masked. Is a method of grooving the outermost surface of the intermediate layer with an argon laser or the like, or grooving with a diamond brush or various grindstones. A rough surface as shown in FIG. 7 is obtained, for example. Is to coat the substrate surface with coarse-grained tungsten, molybdenum, titanium and / or their nitrides, carbides and carbonitrides by ion plating or the like,
This is a method in which nucleation is controlled by a plasma CVD method, an RFCVD method, or the like, and a coating layer having a nonuniform film thickness distribution is provided. FIG. 8 shows a state in which the outermost surface of the intermediate layer is made of aggregates of fine particles and covers the entire surface of the base material. FIG. 9 shows a state in which the outermost surface of the intermediate layer is made of coarse particles and covers the entire surface of the substrate. FIG. 10 shows a state in which the base material is partially covered with the aggregate of fine particles. FIG. 11 shows a state in which the base material is partially covered with coarse particles.

In any case, the outermost surface of the intermediate layer formed at this time is 50 μm at the interface between the boron nitride coating layer and the intermediate layer. The surface roughness at the interface is 0.5% at Rmax.
It is necessary that the projections have a penetration length of 0.2 μm or more in the boron nitride coating layer. The surface roughness at the substrate interface is Rmax,
When the thickness is less than 0.5 μm, no improvement in adhesion strength is observed, and
On the other hand, when the thickness exceeds 0 μm, a decrease in adhesion strength was observed. When the maximum penetration depth of the projection is less than 0.2 μm, the adhesion strength is not substantially changed.

When the intermediate layer is coated over the entire surface, the surface state becomes uniform as compared with the case where the base material itself is roughened, so that nucleation occurs uniformly and a uniform film can be obtained. understood.

It has also been found that the adhesion strength can be improved when the intermediate layer described here is coated with at least 10% or more of the entire surface coated with boron nitride. In other words, 90% of the area is effective even if the substrate is exposed, which corresponds to the case of the above-described means (FIGS. 10 and 11).

Further, it has been found that when the outermost surface of the intermediate layer is a substance containing columnar crystals having an aspect ratio of 1.5 or more or a substance containing needle-like crystals, the adhesion strength is further increased.

Materials constituting the intermediate layer include silicon nitride, a substance containing silicon nitride, sialon, a substance containing sialon, silicon carbide, a substance containing silicon carbide, aluminum oxide, a substance containing aluminum oxide, a group IVa, Va group,
At least one metal selected from Group VIa, Group VIIa, alloys thereof, carbides, nitrides and / or carbonitrides thereof, such as titanium, carbides or carbonitrides of titanium, titanium and other One or more metal carbides or carbonitrides and materials containing them, tungsten, tungsten carbides or carbonitrides,
It is selected from the group consisting of carbides and carbonitrides of tungsten and one or more other metals and substances containing these. The outermost surface of the intermediate layer composed of these is preferably a macroscopically rough surface or a rough surface having microscopic irregularities. Here, Sialon is
Some of Si and N in the silicon nitride crystal are Al and O, respectively.
And α-sialon and β-sialon.

The intermediate layer may have a single-layer structure or a multilayer structure having two or more layers. If the intermediate layer has a multilayer structure, select a material with high adhesion strength to the substrate as the layer in contact with the substrate, and adhere to boron nitride as the layer in contact with the boron nitride coating layer, that is, the layer constituting the outermost surface It is preferable to select a material having high strength. Regardless of whether the intermediate layer is a single layer or a multilayer, the average layer thickness of the entire intermediate layer is less than 0.2 μm, and when the coating area is less than 10%, the improvement in adhesion strength by the intermediate layer is not recognized. When an intermediate layer having a thickness of more than 300 μm is formed, on the contrary, the adhesion strength becomes low. Therefore, the average layer thickness is desirably 0.2 μm to 300 μm. The intermediate layer of the present invention may be formed by any known method such as a CVD method, a PVD method, and a sputtering method, and all of them have the effects of the present invention.

The substrate is made of cemented carbide, cermet, Al ₂ O
_3. Any hard material such as various ceramics such as silicon nitride and silicon carbide can be used. Among them, in particular, titanium compounds such as silicon nitride, silicon carbide, titanium carbide, titanium nitride, and titanium carbonitride and / or substances containing titanium compounds, tungsten carbide and / or
Alternatively, it has been found that when there is unevenness due to carbides of a tungsten alloy and / or substances containing these, high adhesion strength is exhibited.

The average thickness of the boron nitride coating layer is as follows:
If the thickness is less than 0.1 μm, no improvement in performance such as abrasion resistance due to the coating layer is recognized, and even if a coating layer exceeding 300 μm is formed, no significant improvement in performance is recognized anymore. 1 μm to 300 μm is desirable.

In the above description, boron nitride was generally used as the boron nitride coating layer.
If not, there is no practical problem. Even if it contains at least 1% by volume or more of CBN and the other portion is made of other crystalline boron nitride or another element such as boron, carbon, oxygen, iron or cobalt, the improvement in wear resistance due to the presence of the coating layer is recognized. Can be Furthermore, after coating with boron nitride having another crystal type such as hexagonal boron nitride, any heat treatment is performed, and even when the crystal structure of these coating layers changes, the present invention improves the adhesion strength. The effect is recognized. The same effect can be obtained even with a single layer or a multi-layer structure. Next, the present invention will be described specifically with reference to examples.

[0019]

EXAMPLE 1 As a base material, a K10 cemented carbide (specifically,
WC-1.5 wt% NbC-5% Co) and nitrogen
Silicon-based ceramics (specifically, Si_ThreeN_Four-4wt
% Al_TwoO _Three-4wt% ZrO_Two-3wt% Y_TwoO_Three)
To make a throwaway tip with the shape of SPG422
Was. A known gas phase synthesis method is used to coat the chip surface with (1) Al_TwoO_ThreeAn average layer thickness of 3 μm
(Carbide base material) (2) Al_TwoO_Three-TiC coating layer with an average of 3.5 μm
Formed with layer thickness (ceramic base material) (3) Formed TiN coating layer with average layer thickness of 2.5 μm
(Carbide base material) (4) Forming TiN coating layer with average layer thickness of 4.0 μm
(Ceramic base material) (5) Forming SiC coating layer with an average thickness of 3.5 μm
(Carbide base material) (6) Si_ThreeN_FourCoating layer with an average layer thickness of 3.0 μm
Formation (Carbide base material) (7) Form SiC coating layer with average layer thickness of 30 μm
(Carbide base material) (8) Form SiC coating layer with an average layer thickness of 100 μm
(Carbide base material) (9) Si_ThreeN_FourThe coating layer is formed with an average layer thickness of 15 μm.
(Carbide base material) (10) Si_ThreeN_FourForm the coating layer with an average layer thickness of 80 μm
(Carbide base material) On the outermost surface of the chip, (1) and (2) have a minor axis of 1.0.
α-Al with a long diameter of 10 μm_TwoO_ThreeWas precipitated. (3) and (4) have a minor axis of 2.0 μm and a major axis of 5.0 μm
Was precipitated. (5) SiC with a short diameter of 1.5 μm and a long diameter of 9.0 μm
Whiskers were deposited. (6) Si with a minor axis of 2.0 μm and a major axis of 6.0 μm_Three
N_FourColumnar crystals were precipitated. (7) and (8) have a minor axis of 1.5 μm and a major axis of 10 μm.
Whiskers are formed on the outermost surface, and (9) and (10)
1.5 μm short diameter, 5 μm long diameter SiN_FourColumnar crystals as outermost
Deposited on the surface. Each surface roughness is Rmax
It was 3-5 μm. Chip fabricated in this way
The known RF plasma CVD method, the substrate temperature
500 ° C, diborane gas: N_TwoGas = 1: 2 ratio
Up to 0.05 Torr, near the cutting edge of the cutting tip.
The boron nitride coating of the invention having an average layer thickness of 3.0 μm
Coated cutting tips (1) to (10) were produced. Also, in comparison
Therefore, the same shape and the same composition did not cover the intermediate layer.
Chip (Comparative chip 1: cemented carbide base material) and this intermediate layer
A chip without boron was provided with a boron nitride coating layer under the same conditions.
Comparative chip 2 (a cemented carbide base material) was also prepared. In addition, this trial
In the test, the coating layer deposited on the surface of the substrate
By yield analysis, Auger analysis, and transmission electron diffraction, C
A boron nitride coating layer containing at least 1% by volume of BN
confirmed.

Using these cutting tips, work material: FC30 round bar having H230 Cutting speed: 1000 m / min Feed: 0.3 mm / rev. Depth of cut: 1.5 mm Cutting oil: Emulsion type Wet cutting was performed under the following conditions, and the cutting time until the flank wear of the cutting edge, which is considered to be the service life, reached 0.1 mm was examined. While the chip was 18 to 22 minutes, the comparative chip 1 was 2 minutes and the comparative chip 2 was 3.5 minutes, and it was observed that the boron nitride coating layer was largely peeled off.

After cutting and lapping the chip after the cutting test, the interface between the outermost surface of the intermediate layer and the diamond coating layer was observed with an optical microscope.
(2) α-Al ₂ O ₃ , (3) and (4) needle-like TiN, (5), (7) and (8) SiC whiskers, (6) and (9) In (10) and (10), the silicon nitride columnar crystals have a maximum thickness of 2 μm in the boron nitride coating layer.
m to 4 μm in depth, and the outermost surface of the intermediate layer
The microscopic surface roughness at the reference length of 50 μm at the boron nitride coating layer interface was 3 μm to 4 μm in Rmax. Further, in Comparative Chips 1 and 2, no penetration into the boron nitride coating layer into the base material was observed.

Example 2 K10 cemented carbide (specifically, WC-5% C
o) and nitrogen-containing cermet (specifically, 38 wt%
TiC-12wt% TiN-10wt% TaN-10w
_{t% Mo 2 C-15wt%} WC-5wt% Ni-10w
(t% Co) to produce a throw-away tip having a shape of SPG422. Using a known ion plating method on the surface of this chip, (1) a coating area of 30% near the W cutting edge having a particle size of 0.5 μm (carbide base material) (2) near a W cutting edge having a particle size of 1 μm (3) Coating area near the W cutting edge with a particle size of 1.2 μm (Carbide base material) (4) Coating area 6 near the W cutting edge with a particle size of 1 μm
0% (cermet base material) (5) Coating area 60% near Ti cutting edge with a particle size of 1 μm (carbide base material) (6) Coating area 60% near Ti cutting edge with a 1.5 μm particle size (cermet base material) (7) Coating area near the Mo cutting edge with a particle size of 2.0 μm 60% (carbide base material) (8) Coating area near the Mo cutting edge with a particle size of 2.5 μm 100% (carbide base material) Were each coated as an intermediate layer. Except for (3), the chip surface roughness was 2 μm to 2.5 μm in Rmax. (3) is 0.
It was 7 μm. For comparison, comparative chips 1 (carbide alloy) and 2 (cermet) without these intermediate layers were prepared. These chips, including comparative chips, were subjected to a known high-frequency sputtering method using a hexagonal BN target as a target, and a basic heating temperature of 20.
0 to 500, an atmosphere N ₂ / Ar ratio of 1/10, an atmosphere pressure of 0.01 Torr, a bias voltage of 100 V, a reaction temperature of 10 hours, and a boron nitride-coated cutting tip 1 to 6 having a layer thickness of 5 μm (hereinafter referred to as the present invention). Cutting tips 1-6),
Comparative chips 1 and 2 were produced. The coating layer deposited on the surface of the base material in this test contained 1% by volume of CBN by infrared absorption analysis, Auger analysis, and transmission electron diffraction.
It was confirmed that there was a boron nitride coating layer containing the above.

Using these cutting tips, work material: round bar of FC30 having H230 Cutting speed: 1000 m / min Feed: 0.3 mm / rev. Depth of cut: 1.5 mm Cutting oil: Emulsion type Wet cutting was performed under the following conditions, and the cutting time until the flank wear of the cutting edge, which is considered to be the service life, reached 0.1 mm was examined. The chip except for (3) was 22 to 24 minutes, the comparative chip 1 was 2 minutes, and the comparative chip 2 was 3 minutes, and it was observed that the coating layer was largely peeled. In the chip (3) of the present invention, it was observed that the boron nitride coating layer was slightly peeled off in 18 minutes.

After cutting and lapping the chip after the cutting test, the interface between the substrate and the boron nitride coating layer was observed with an optical microscope. It penetrated at a depth of 2.0 μm, and the surface roughness within a reference length of 50 μm was 1.5 μm to 2.5 μm at Rmax. In (3), the microscopic Rmax was 0.4 μm.

[0025]

It can be seen that the boron nitride-coated hard material of the present invention has better peel resistance as compared with the conventional boron nitride-coated hard material. Although the present embodiment shows the case where a cemented carbide, a silicon nitride-based ceramic, a nitrogen-containing cermet is used as a base material and applied to a cutting tool, various kinds of ceramics mainly containing silicon carbide, Al ₂ O ₃ , etc. Even when a hard material is used as a base material, it can be expected that good results can be obtained. It can be expected that good results can be obtained also when applied to wear-resistant tools such as TAB tools and mechanical parts. In addition, it can be applied to end mills, drills, drills for drilling printed circuit boards, and reamers.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram schematically showing a state of an interface between an intermediate layer and a boron nitride coating layer according to the present invention.

FIG. 2 is an explanatory diagram simulating the state shown in FIG. 1 as a straight line.

FIG. 3 is an explanatory view of an example in which a rough surface is formed by a scratching process with a grindstone or the like in the present invention.

FIG. 4 shows columnar crystals and / or
FIG. 4 is an explanatory view of an example in which a needle-like crystal is covered to form a rough surface.

FIG. 5 is an explanatory view of an example in which the surface of the intermediate layer is etched to have a rough surface in the present invention.

FIG. 6 is an explanatory view of an example in which a mask is applied to the outermost surface of the intermediate layer and then etched to form a rough surface in the present invention.

FIG. 7 is an explanatory diagram of an example in which a rough surface is formed by physical processing using a laser or the like in the present invention.

FIG. 8 is an explanatory diagram of an example in which an aggregate of fine particles is coated on the entire surface of a base material in the present invention.

FIG. 9 is an explanatory diagram of an example in which coarse particles are coated on the front surface of a substrate in the present invention.

FIG. 10 is an explanatory diagram of an example in which a fine particle aggregate is partially coated on a base material in the present invention.

FIG. 11 is an explanatory view of an example in which coarse particles are partially coated on a base material in the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) C23C 16/00-16/56 C23C 14/00-14/58 C04B 41/87-41/89

Claims (13)

(57) [Claims] 1. A hard material coated with a boron nitride coating layer formed on a surface of a hard material, wherein at least one intermediate layer exists between the surface of the base material and the boron nitride coating layer, A boron nitride-coated hard material having a surface roughness of 0.5 μm or more in Rmax. 2. A coated hard material having a boron nitride coating layer formed on the surface of a hard material, wherein at least one intermediate layer exists between the substrate surface and the boron nitride coating layer, At the interface between the surface and the boron nitride coating layer, (1) microscopic unevenness is present, and (2) when the reference length is 50 μm,
The surface roughness within this reference length is 0.5 to 30 μm at Rmax.
A hard material coated with boron nitride, characterized in that: 3. The boron nitride-coated hard material according to claim 1, wherein an area covered by the intermediate layer is at least 10% of an area covered with boron nitride. 4. The method according to claim 1, wherein the outermost surface of the intermediate layer is made of a material selected from the group consisting of a substance containing silicon nitride, silicon nitride, sialon, a substance containing sialon, and a substance containing these. Item 4. The boron nitride-coated hard material according to any one of Items 1 to 3. 5. The boron nitride-coated hard material according to claim 1, wherein the outermost surface of the intermediate layer is made of silicon carbide and / or a substance containing silicon carbide. 6. The boron nitride-coated hard material according to claim 1, wherein the outermost surface of the intermediate layer is made of aluminum oxide and / or a substance containing aluminum oxide. 7. The intermediate layer having an outermost surface comprising: (1) Group IVa, Va
At least one metal selected from the group consisting of group VIa, group VIa and group VIIa and / or an alloy thereof; and (2) at least one selected from the group consisting of carbides, nitrides and / or carbonitrides thereof. The boron nitride-coated hard material according to any one of claims 1 to 3, wherein the hard material is made of the following material. 8. The intermediate layer having an outermost surface comprising: (1) titanium,
(2) a carbide or carbonitride of titanium, (3) a carbide or carbonitride of titanium and one or more other metals, and (4) at least one member selected from the group consisting of substances containing these. The boron nitride-coated hard material according to claim 7, wherein the hard material is made of a material. 9. The intermediate layer having an outermost surface comprising: (1) tungsten, (2) a carbide or carbonitride of tungsten,
(3) At least one material selected from the group consisting of carbides or carbonitrides of tungsten and one or more other metals and (4) substances containing these. Item 7. A boron nitride-coated hard material according to item 7. 10. The boron nitride-coated hard material according to claim 1, wherein a columnar substance having an aspect ratio of 1.5 or more exists on the outermost surface of the intermediate layer. 11. The boron nitride-coated hard material according to claim 1, wherein a substance having a needle shape is present on an outermost surface of the intermediate layer. 12. The hard material comprises: (1) a cemented carbide, (2)
The boron nitride-coated hard material according to any one of claims 1 to 11, wherein the material is a cermet, (3) various ceramics such as Al ₂ O ₃ , silicon nitride, and silicon carbide, or (4) a composite material thereof. material. 13. An intermediate layer having an average layer thickness of 0.2 μm
The boron nitride-coated hard material according to any one of claims 1 to 12, wherein the thickness is from 300 to 300 µm.