JPH0633240A - Boron nitride coated hard material and its production - Google Patents

Abstract

PURPOSE:To provide the boron nitride coated hard material and the process for production of this material. CONSTITUTION:The boron nitride coated hard material constituted by using titanium-base cermet or titanium carbonitride-base cermet as a base material and providing the surface of this base material with a boron nitride coating layer is so formed that the existence ratio of the bond layer in the surface part of the base material is lower than that in the base material or the bond layer in the surface part of the base material does not exist. More particularly preferably, the surface part of the base material is a surface reformed layer having a sintered case and heat treated case. The boron nitride coated hard material is produced by subjecting the base material to sintering and heat treating, then coating the material with the boron nitride. Since the material has extremely high wear resistance and the adhesive strength to the base material, the material is advantageously utilizable for various kinds of tools, parts, grinding wheels, etc.

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 extremely high wear resistance and a method for producing the same, and the present invention products include cutting tools, wear resistant tools, mining tools, electronic parts and machines. It is suitable for use in parts and grindstones. In particular, the work material and work material is steel or cast iron rolls, guide rollers, seal rings, rocker arm tips, wear resistant tools such as nozzles and dies, and boron nitride hard materials suitable for use as cutting tools and the like. Regarding manufacturing method.

[0002]

2. Description of the Related Art Boron nitride is a hexagonal boron nitride (h-
BN), wurtzite type boron nitride (w-BN), cubic boron nitride (hereinafter also abbreviated as “c-BN”), amorphous type boron nitride, etc. are known to have a crystal structure. c-BN has room temperature hardness next to diamond,
Further, it is known that it is more stable at high temperature than diamond, and therefore diamond easily reacts with ferrous metals, but it does not react even at high temperature, and high temperature strength is also high. Therefore, when c-BN or a coating layer containing c-BN is coated on the surface of a cutting tool, a wear resistant tool or other machine parts, good wear resistance can be expected. In particular, the workpieces and work materials are steel and cast iron rolls, guide rollers, seal rings, rocker arms, chips, nozzles, and wear-resistant tools such as dies and dies, provided on the surface of cutting tools. In this case, good abrasion resistance can be expected.

In recent years, there has been an increasing demand for machining hard-to-machine and hard-to-machine materials such as hardened steel and ductile cast iron, and there is a strong demand for high efficiency in these machining conditions. ing. In order to respond to the importance of such a market, Japanese Patent Publication No. 57-49621 and Japanese Patent Publication No. 58-
19737, Japanese Patent Publication 58-55111, Japanese Patent Publication 57-3631, Japanese Patent Publication 52-17519, Japanese Patent Publication 50-39444, Japanese Patent Publication 52-1.
A c-BN sintered body produced by sintering c-BN granular crystals and a special ceramics binder under ultrahigh pressure by the method disclosed in many patent publications including 7838 publication is used. The cutting tools and abrasion resistant tools that were used are in practical use.

In addition, attempts have been made to form a boron nitride coating layer on the surface of a base material to significantly improve the abrasion resistance of the base material. As a method of manufacturing the artificial boron nitride coating layer,
A thermal CVD method, a microwave plasma CVD method, an RF plasma CVD method, an ion plating method, a sputtering method, an ion beam assisted vacuum deposition method, which are disclosed in many patent publications including Japanese Patent Publication No. 60-181262. Various methods and combinations of these are known,
These are powerful methods for producing boron nitride coated hard materials.

[0005]

By the way, various tools and the like that can be produced by brazing a c-BN sintered body to a base metal have restrictions in shape. Specifically, it is difficult to braze the boron nitride sintered body to all the blade parts having a shape like a four-blade end mill with excellent accuracy by the current technology. For this reason, it is necessary to prepare a round bar-shaped c-BN sintered body and perform electric discharge machining to obtain a target shape. The c-BN sintered body is also applied to parts other than those actually required to improve wear resistance. Since it is composed of a body, it is very expensive, and productivity and shape flexibility are low. On the contrary, the boron nitride-coated hard material has a very high degree of freedom in shape and productivity. However, most of the hard materials coated with boron nitride lack adhesion between the substrate and the boron nitride coating layer. In particular, when applied to severe conditions such as a cutting tool, the boron nitride coating layer is often peeled to reach the end of its life.

In order to improve this point, many organizations have tried to provide an intermediate layer between the substrate and the boron nitride coating layer. For example, JP-A-60-204687
JP-A-60-152677, JP-A-63
-35774, JP-A-63-239103, JP-A-64-28358 and the like. There is also disclosed a technique in which the adhesion between the boron nitride coating layer and the base material is enhanced when ceramics is used as the base material (Japanese Patent Laid-Open No. 60-204686).
Japanese Patent Publication No. Sho 60-59085). Also, the substrate is treated with plasma such as Ar or H ₂ to remove impurities on the surface,
The applicant has already filed a patent application in Japanese Patent Application No. 2-243859 to secure the adhesion strength with a substrate by forming a boron nitride coating layer on the clean surface thus obtained. There is. Furthermore, the surface of the base material has irregularities,
There is also a technique of forming a boron nitride coating layer on this to enhance the mechanical bonding force between the coating layer and the base material (Japanese Patent Application No. Hei 3 (1999) -135242).
-41843).

In the above-mentioned prior art, when an intermediate layer is provided, it is difficult to select an intermediate layer material capable of joining the intermediate layer and boron nitride, and the boron nitride and the base material at the same time with excellent adhesion. Peeling of the coating layer occurred inside the substrate-intermediate layer or inside the intermediate layer. Although it has been confirmed that the technique of Japanese Patent Application No. 3-41843 is effective, there is still room for improvement in improving the adhesion between the boron nitride coating layer and the substrate even if this technique is used. . Further, when ceramics is used as the material of the base material, the strength of the base material is low irrespective of its adhesive strength, and therefore when applied to a cutting tool, for example, it is often broken or chipped. An object of the present invention is to solve these problems and to provide a boron nitride-coated hard material having excellent adhesion strength, strength and freedom of shape.

[0008]

As a means for solving the above problems, the inventors of the present invention have widely used titanium carbide-based or titanium carbonitride-based materials, which are widely used as materials for cutting tools and wear-resistant tools and have many excellent characteristics. Selecting a cermet, and that the method of increasing the adhesion strength of the coating layer by improving the surface state of the substrate forming the boron nitride coating layer is effective,
That is, it was found that the above objects can be achieved by the following boron nitride-coated hard materials (a) to (j) and manufacturing methods. (A) A boron nitride-coated hard material comprising a titanium carbide-based cermet or a titanium carbonitride-based cermet as a base material, and a boron nitride coating layer provided on the surface of the base material. A boron nitride-coated hard material, characterized in that the proportion thereof is smaller than that in the inside of the base material or that no binder phase is present in the surface portion of the base material. (B) In a boron nitride-coated hard material comprising a titanium carbide-based cermet or a titanium carbonitride-based cermet as a base material and a boron nitride coating layer provided on the surface of the base material, the outermost surface of the base material has a higher hardness than the inside. A boron nitride-coated hard material characterized by the presence of a surface modification layer which is (C) In a boron nitride-coated hard material comprising a titanium carbide-based cermet or titanium carbonitride-based cermet as a base material and a boron nitride coating layer provided on the surface of the base material, at least a part of the base material surface is sintered. A boron nitride-coated hard material, which is skin and has a boron nitride coating layer formed on at least a portion of the sintered skin. (D) A boron nitride-coated hard material comprising a titanium carbide-based cermet or a titanium carbonitride-based cermet as a base material and a boron nitride coating layer provided on the surface of the base,
At least a part of the surface of the base material is a sintered skin, and a surface layer having a binder phase and / or a ratio of the binder phase higher than the inside is present on the surface of the sintered skin. A boron nitride-coated hard material, characterized in that a coating layer is formed. (E) A boron nitride-coated hard material comprising a titanium carbide-based cermet or a titanium carbonitride-based cermet as a base material and a boron nitride coating layer provided on the surface of the base,
After the base material is processed into an arbitrary shape, the base material is heat treated to form a boron nitride coating layer on at least a part of the surface of the base material or at least part of the surface of the base material, which is heat treated skin. A boron nitride-coated hard material characterized by being formed. (F) In a boron nitride-coated hard material comprising a titanium carbide-based cermet or a titanium carbonitride-based cermet as a base material and a boron nitride coating layer provided on the surface of the base material, after processing the base material into an arbitrary shape, At least a part of the surface properties of the base material is treated by heat-treating the base material, and at least a part of the surface of the heat-treated skin surface is obtained by removing the surface phase having the binder phase and / or the ratio of the binder phase higher than the inside. Alternatively, a boron nitride-coated hard material comprising a boron nitride coating layer formed on the entire surface. (G) Sintering and / or cooling of the cermet as a base material is performed in an atmosphere in which the partial pressure of N ₂ and / or CO and / or CH ₄ is 1 Torr or more, and at least a part of the obtained sintered body A method for producing a boron nitride-coated hard material, characterized in that the surface is a sintered skin, and a boron nitride coating layer is further provided on at least a part of the surface of the sintered skin. (H) Sintering and cooling the cermet, which is the base material,
Performing in a nitrogen gas atmosphere of Torr or more, and providing a boron nitride coating layer on at least a part of the surface of this sintered body by etching away the metal component leached on the surface with an acid and / or an alkali. A method for producing a hard material coated with boron nitride, comprising: (I) After sintering the cermet to be the base material and processing it into a target shape, at least a part of the surface of the base material is 900 to 1
Heat treatment at a temperature of 600 ° C. or higher for 10 minutes to 5 hours,
Next, by cooling in an atmosphere having a partial pressure of CO of 1 Torr or more, at least a part of the surface of the base material is a heat-treated skin, and a boron nitride coating layer is further provided on at least a part of the surface of the heat-treated skin. Method for producing hard material coated with boron nitride. (J) Cermet as a base material is sintered and processed into a target shape, and then 800 in 1 Torr or more of N ₂ gas.
Heat treatment is performed for 10 minutes to 5 hours at a temperature of 1600 ° C. or higher, and then cooled to form at least a part of the surface of the substrate as a heat treated skin, and the metal component leached on the surface of the heat treated skin is treated with an acid and / or an acid. A method for producing a boron nitride-coated hard material, characterized in that a boron nitride coating layer is provided on a part of the surface removed by etching with an alkali. As a particularly preferred example of the “surface portion in which the existence ratio of the binder phase is smaller than that of the inside or the binder phase does not exist” of the present invention,
A layer having a different composition and / or structure from the inside of the substrate, that is, a layer referred to as a “surface modified layer” in the present invention, is present on the surface portion of the substrate. In the above manufacturing method of the present invention, the sintering pressure is set to 1 as the sintering or heat treatment.
It is particularly preferable to carry out hot isostatic pressing under the condition of 0 to 3000 atm, and it is also particularly preferable to carry out the heat treatment step and the boron nitride coating layer forming step continuously.

[0009]

As a result of many trials and errors, the present inventors have a surface portion in which the composition ratio of the binder phase is smaller than that in the interior as in (a) or where the binder phase does not exist, or (b)
It has been discovered that when a titanium carbide-based cermet or titanium carbonitride-based cermet as described in (f) is used as a base material, a boron nitride coating layer having excellent adhesion can be obtained. The reason for this is not clear, but the conjecture is described below.
Generally, diamond is a carbide, nitride, boride, oxide, carbonitride, or boronitride of 4A, 5A, or 6A group elements (excluding W) of the periodic table including WC, metal W, and Ti. It is known to show high nucleation densities on carbides, nitrides or carbonitrides and on these solid solutions, and thus good adhesion strength. Boron nitride, especially c-
Since BN has a crystal structure similar to that of diamond, it also has good adhesion on these materials, and conversely the presence of iron-based metals may reduce the adhesion. The inventors have come up with an idea.

In the present invention, since a titanium carbide-based cermet or titanium carbonitride-based cermet is used as the base material, the problem of peeling of the intermediate layer unlike the technique using the intermediate layer does not occur, and the base material The strength of the base material does not decrease when the binder phase therein is removed by etching or the like.

The titanium carbide-based or titanium carbonitride-based cermet used as the base material in the present invention is mainly composed of a hard dispersed phase of 4A, 5A and 6A metals and Si carbides, nitrides, carbonitrides and borides. Of 60% by weight or more in terms of carbides, nitrides or carbonitrides, and the rest is composed of at least one of iron-based metals as a binder phase.

The surface of the base material of the present invention is in a state where the proportion of the binder phase is smaller than that in the interior, or the binder phase is not present, specifically, the surface modification layer, the sintered skin and / or the heat treated skin, A method for producing a boron nitride-coated hard material will be described below. As one method, when mixing, shaping, sintering, and cooling titanium carbide-based or titanium carbonitride-based cermet raw material powder, the atmosphere during sintering and / or cooling is set to equilibrium O ₂ and Examples of the method include sintering in an atmosphere gas having a partial pressure higher than that of N ₂ and / or CH ₄ and forming a boron nitride coating layer on the sintered surface. To adjust the O ₂ partial pressure to a desired partial pressure, a CO gas atmosphere may be used. Further, the base material that has been subjected to arbitrary sintering and once subjected to grinding processing is heat-treated again under the above-mentioned conditions, and the surface property of the base material is in a state close to a sintered surface (hereinafter referred to as "heat-treated surface"). Also by
Similarly, since the above state can be achieved, a boron nitride coating layer may be formed on this heat-treated skin. In addition,
If there is a surface layer (referred to as a binder phase layer) formed by the binder phase component on the surface, it is necessary to remove this binder phase layer in order to form the boron nitride coating layer.

In the manufacturing method of the present invention, the sintering temperature and time may be the conditions used for the usual sintering of cermet. Specifically, at a temperature of 1300 ° C to 1500 ° C,
30 to 3 hours is typical. The above-mentioned O ₂ and / or N ₂ gas atmosphere may be introduced from the early stage of sintering, from the middle stage, or at the cooling stage.
If the temperature is not kept in the range of 600 ° C. for at least 10 minutes or more, the mass transfer to the interface of the hard phase is not sufficient and the generation of the surface modified layer is not recognized.

The heat treatment conditions in the present invention are the same as the sintering conditions, that is, at a temperature of 1300 ° C. to 1600 ° C.
3 hours is typical. The CO atmosphere may be set from the beginning of the heat treatment, the middle stage, or the cooling stage.
Unless held in the range of 00 ° C to 1600 ° C for at least 10 minutes or more, the hard phase does not sufficiently move to the interface,
The generation of the surface modified layer is not observed, which is not preferable.
Further, when heat treatment is performed for a long time exceeding 1000 minutes, strength is deteriorated due to coarsening of hard phase particles of the base cemented carbide, which is not desirable. Here, it is possible to perform the step of coating the substrate surface with boron nitride continuously without cooling the substrate to room temperature and / or in the same vacuum container, which is industrially effective. It is a means.

The decrease in the binder phase on the surface can be detected because the surface portion of the base material has a higher hardness than the inside. Specifically, the hardness is 5% or more higher than the Vickers hardness inside the substrate. In addition, the diffraction intensity of the hard phase is lower than that when the surface (the surface on which the boron nitride coating layer is formed) is subjected to X-ray diffraction and the inside of the base material is subjected to X-ray diffraction. , Is detectable. As a result of observing and analyzing the surface properties and cross-sections of the sintered skin and the heat-treated skin produced by the above-described method of the present invention, the surface of the base material has a surface-modified layer having a different composition and / or structure from the inside. It was confirmed. In this surface-modified layer, hardness increase of at least 5% or more is recognized from the inside.

It has also been found that good adhesion strength of the boron nitride coating layer can be obtained when the boron nitride coating layer is formed on the sintered skin or the heat treated skin regardless of the presence or absence of the surface-modified phase. As a cause of this, the sintered skin or the heat-treated skin has macroscopic unevenness and / or microscopic unevenness on the surface, as compared with a surface ground by a diamond wheel or the like (hereinafter referred to as ground surface), It can be inferred that this causes geometrical entanglement between the boron nitride coating layer and the WC-based cemented carbide substrate, which increases the physical bonding force between the two. The macroscopic surface roughness, which is an index of the size of macroscopic unevenness, is the surface roughness due to unevenness at a level that can be detected by a surface roughness meter by a generally used stylus method (J
IS B 0601 description). The present inventors have discovered that the microscopic surface roughness due to the presence of microscopic concavities and convexities largely contributes to the adhesion of the boron nitride coating layer, rather than the macroscopic surface roughness. The microscopic surface roughness is the surface roughness within the reference length, where the reference length is a minute section such as 50 μm at the interface between the boron nitride coating layer and the outermost surface of the substrate. For this, the cross section of the substrate after the boron nitride coating was observed by lapping, and a photograph was taken, and the surface roughness of the substrate after coating was calculated with the boundary line between the boron nitride coating layer and the substrate. Here, the difference between the maximum height and the minimum height of the boundary line within the reference length is expressed as Rmax ^* . However, at this time, macroscopic swell was calculated by linear approximation.

In the present invention, the surface roughness of the substrate surface is
When measured by the stylus method, JIS standard Rmax is 1.
It was confirmed that when the thickness is 5 μm or more, it has a great effect in improving the adhesion. Alternatively, it was confirmed that the microscopic surface roughness obtained by observing the cross section as described above has a great effect on the improvement of the adhesive force even when Rmax ^{* is} 2 μm or more.

On the sintered skin and the heat-treated skin according to the present invention, leaching of the binder phase may be observed on the surface depending on the amount of carbon in the sintered body, the sintering method and the like. In this case, it was found that the boron nitride coating layer formed on the surface of the binder phase would be easily peeled off unless the binder phase was removed. Examples of the method of removing the leached binder phase include etching, blasting, barreling and the like. Here, in mechanical processing such as blasting and barreling, the surface roughness of the surface is improved, and the effect of improving the adhesion strength due to deterioration of the surface roughness is diminished, so etching removal is desirable. Etching here is not for the purpose of corroding the base material described in the section describing the conventional technique but for removing the leached binder phase, and therefore the surface modification layer does not contain the binder phase. In this case, the base material does not have a corrosive layer at all, and even when a binder phase is present, the component ratio is extremely small, so that the strength of the base material is not deteriorated. The same can be said for the removal treatment for the leached binder phase for heat treated skin.

In the present invention, the distribution of the proportion of the binder phase in the surface-modified layer varies depending on the sintering conditions and heat treatment conditions thereof, and may be continuously reduced toward the surface or may be intermittently reduced. Good. Also, when performing heat treatment on the base material after sintering and grinding the base material, strength deterioration due to coarsening of crystal grains is reduced as much as possible, and at the same time defects (pores) inside the base material
Strength can be expected to be improved by decreasing Lower temperature compared to sintering temperature, preferably 1200 ° C-155
It is desirable to carry out hot isostatic pressing at a temperature of 0 ° C. At this time, the hydrostatic pressure can be expected to be more excellent when it is at a high pressure, but from an industrial viewpoint, it is 10 atm to 3000 atm.
Atmospheric pressure is desirable.

In the process of forming the boron nitride coating layer from the heat treatment, it is industrially desirable to continuously process the same in the same equipment. That is, the sintered and ground base material is placed in a boron nitride coating facility, first subjected to heat treatment under the above-described conditions before the boron nitride coating, and then the boron nitride coating layer forming process is continuously performed.

Here, regarding the layer thickness of the surface modified layer,
If it is less than 0.01, the influence of the binder phase component in the base material becomes strong, and it does not contribute to the improvement of the adhesion strength of the boron nitride coating layer. To completely block this effect, 0.1μ
m or more, more preferably 0.5 μm or more. The upper limit is 100 in order to maintain the strength of the base material.
It is preferably 0 μm or less.

The layer thickness of the boron nitride coating layer may be a layer thickness necessary for each application. However, in use applications where abrasion resistance is required, improvement in various properties such as abrasion resistance due to the coating layer is not recognized when the layer thickness is less than 0.5 μm, and even when a coating layer exceeding 300 μm is formed, For economic reasons, 0.5 μm to 300 μm is desirable because no significant improvement in performance can be observed.

The boron nitride coating layer described so far does not need to have all the constituent crystals of c-BN, and if at least 5% by volume or more of c-BN is contained, the abrasion resistance of the base material is improved. Make a big contribution. Further, after coating with h-BN or other boron nitride, a treatment such as heating may be performed to obtain c-BN. Even when the coating layer contains phosphorus, oxygen, etc., the high adhesive strength with the base material, which is the greatest feature of the present invention, is not impaired. Further, as the method for coating boron nitride, any of the methods described in the section of the conventional art and combinations thereof may be used. Further, even if the surface of the boron nitride coating layer is smoothed or mirror-finished by a grindstone, heat treatment, or the like in order to obtain a predetermined surface roughness and / or dimensional accuracy, the superiority of the present invention is not impaired. Further, in order to obtain a predetermined surface roughness and / or dimensional accuracy, even if the surface of the boron nitride coating layer is smoothed or mirror-finished by a grindstone or heat treatment,
The excellence of the present invention is not impaired.

[0024]

EXAMPLES Next, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. [Example 1] In this example, a comparison between a ground surface and a sintered surface is made. Various powders having an average particle diameter of 0.8 to 1.5 μm were prepared as a base material, compounded into the composition shown in Table 1, crushed using a vibration mill, and a binder was added to the powder. Processed, inscribed circle: 12.7 mm, thickness: 3.1
JIS B4103 with 8 mm and corner R: 0.8 mm
A press-molded product having the shape of SPGN422 described in 1. was produced, debindered at 300 ° C., and then sintered under the conditions shown in Table-2. Show the surface condition of this sintered skin-
6 shows. In some of them, leaching of the metal component had occurred on the surface of the sintered body, so this was removed by etching to produce base material chips. Etching method, surface roughness Rmax after etching (JIS B 0601)
Table 6 also shows (measured by a normal stylus method in accordance with the above).

[0025]

[Table 1]

[0026]

[Table 2]

These base material chips were processed by the method shown in Table-3. A schematic example of the cutting edge treatment of chips is shown in FIG. FIG. 1 is a cutting edge process generally called chamfer honing, where α is 25 °, β
Was 20 ° and L was 0.05 mm. A commercially available resin-bonded diamond grindstone was used for the processing of the cutting edge surface, the upper and lower surfaces, and the side surface.

[0028]

[Table 3]

The base material of the chip thus prepared, the sintering conditions, the surface roughness R before the formation of the boron nitride coating layer
Table showing max, Rmax ^* , leaching binder phase removal method, and chip processing method (processing chips after removal of binder phase)
6 shows. By using these RF chips, a substrate temperature is set to 600 ° C. and diborane gas: N ₂ gas is introduced to 1 Torr at a ratio of 1: 2 to form a boron nitride coating layer by using these prepared chips. Inventive boron nitride coated chips No. 1 to No. 24 were manufactured. The thickness of the boron nitride coating layer near the cutting edge of each chip is also shown in Table-6. In this example, the coating layer deposited on the surface of the substrate was confirmed to be a boron nitride coating layer containing 1% by volume or more of c-BN by infrared absorption analysis, Auger analysis and transmission electron diffraction method. .

Further, Rmax ^* written in Table 6 is the microscopic surface roughness of the surface of the base material chip, and the reference length at the base material-boron nitride coating layer interface was set to 50 μm. By the surface roughness in this minute section, lapping observation of the cross-section of these chips, photographed, and the surface roughness of the substrate after coating with the boundary line of the boron nitride coating layer-base material, The difference between the maximum height and the minimum height within the standard length is expressed as Rmax ^* . The Rmax of the ground surface is 0.6
μm and Rmax ^* were 0.8 μm, and no specific layer was found on the surface. In Table 6, the numbers marked with * on the right shoulder of the chip of the present invention are beyond the range recommended as being particularly preferable in the present invention, or outside the range of the present invention.

Further, for comparison, boronitride was used on the entire ground surface.
A comparative cermet chip that does not have a bare coating (that
(Comparative chips A, B, and C respectively), and the composition is Si
₃N _Four-3Al₂O₃-5ZrO₂With the same shape tip
Prepare (1 surface grinding, with cutting edge treatment in Figure 1)
Hold at 800 ℃, 5atm for 1 hour, 8μ long diameter on the surface
m, free-growing Si with minor axis of 1.5 μm₃N_FourColumnar crystals
For the deposited base material chips, use the same method as above.
Silicon nitride ceramic substrate with a boron nitride coating layer
Boron nitride coated chip (comparative chip D), and commercially available
Superhard bonding of boron nitride sintered body containing 10% by volume of binder phase
Brazing to gold (composition: WC-6 wt% Co) and grinding
And the same shape manufactured by applying the cutting edge treatment shown in FIG.
The boron nitride sintered body chip (comparative chip E) of
Equipped

The contents of the binder phase layer removing process in Table 6 are as follows. * 1: Washing with 5% nitric acid at 30 ° C for 5 minutes. This removed the binder phase layer. As a result of cross-sectional observation, the surface of the base material was completely covered with the surface-modified layer formed of the hard phase, whereby no corrosive layer was found inside the base material. * 2: Shot blasting was performed for 15 seconds, whereby the binder phase layer was removed.

Using these cutting tips, the following Table-4 is used.
Wet continuous cutting test under the conditions of 5 minutes and 60 minutes later
The amount of flank wear after the minute and the state of the cutting edge were observed, and the results are also shown in Table-6.

[0034]

[Table 4]

Further, as a wet intermittent cutting test, the following Table-5 is given.
Under the conditions of, each tip is cut with 16 cutting edges,
Table 6 also shows the results of examining the number of cutting edges at which defects occurred.

[0036]

[Table 5]

[0037]

[Table 6]

[0038]

[Table 7]

With respect to the chips No. 1, No. 4 and No. 11 of the present invention, the hardness of the surface portion and the inside was observed by cross-section observation and the load 20
When Vickers hardness was measured at 0 g, the hardness of the base material surface portion was improved by 5 to 15%. N for comparison
As a result of the same measurement for o.13 ^* and No.14 ^* , no increase in hardness was observed.

Further, the present invention chip No. 4 and the present invention chip N
Regarding o.14 ^* , the diffraction curve was measured by Cu-Kα ray on the surface where the boron nitride coating layer was formed on the sintered skin, and as a result, the diffraction intensity of Co and Ni as the bonding phase was N.
It was confirmed to be smaller than o.14 ^* .

From these results, it can be seen that the chip of the present invention is excellent in the adhesion strength of the boron nitride coating layer particularly on the surface of the sintered surface. Further, in the chip of the present invention, a tough cermet is used as a base material while exhibiting wear resistance almost equal to that of a boron nitride sintered body brazing tool, and a Si ₃ N ₄ sintered body is used as a base material. It can be seen that the toughness is higher than that of the comparative tip.

[Embodiment 2] In this embodiment, a comparison between a ground surface and a heat-treated surface is made. As a base material, the average particle size is 0.8-
Various powders of 1.5 μm were prepared, compounded to have the composition shown in Table-1, crushed using a vibration mill, and those to which a binder was added were press-molded and molded, and an inscribed circle: 12.7.
mm, thickness: 3.18 mm, corner R: 0.8 mm, a SPGN422 shape press-formed product described in JIS B4103 is manufactured, and after debinding at 300 ° C., it is 1500 ° C. in an atmosphere of N ₂ · 10 Torr. At 6
It hold | maintained for 0 minute and sintered. The entire surface of this chip was ground, and then heat-treated under the conditions shown in Table 2 to obtain a heat-treated skin. The heat treatment time is 60 minutes in all cases. After removing the binder phase from these chips as needed, the base material chips of the present invention were manufactured by further performing the processing shown in Table-7.

[0043]

[Table 8]

These base material chips were manufactured by using a known high frequency sputtering apparatus, using h-BN as a target, a chip heating temperature of 500 ° C., an atmosphere N ₂ / Ar ratio of 1/10, and an atmospheric pressure of 0. Inventive chips No. 17 to No. 38 were manufactured by forming a boron nitride coating layer having a layer thickness shown in Table 8 at 01 Torr and a bias voltage of 100V. Among them, No. 22 and No. 37 are heat treatment and boron nitride coating performed in the same vacuum container, and after heat treatment, cooled to the boron nitride coating temperature under the cooling conditions in the table, and continuously boron nitride coating layer Was formed in a continuous process of heat treatment-boron nitride formation. In the table, a chip number marked with * on the right shoulder is beyond the range particularly recommended in the present invention. Table 8 also shows the surface condition after the heat treatment, the method for removing the binder phase layer, and the surface roughnesses Rmax and Rmax ^* of the boron nitride coated surface.
The meaning of * 1 in Table-8 is the same as in Example 1, and Rmax and Rmax ^* are the results of the same measurement as in Example 1.

Using these chips, the same continuous cutting test and interrupted cutting test as in Example 1 were carried out. The results are also shown in Table-8. With respect to the chip of the present invention, the hardness of the surface portion and the internal portion was measured by cross-section observation, and the Vickers hardness was measured under a load of 200 g. As a result, No. 18, No. 21, and No. 32 have the same hardness as the first embodiment. It was improved by 5 to 15%. Further, as a result of measuring a diffraction curve by Cu-Kα ray on the surface on which the boron nitride coating layer of No. 18 and No. 34 was formed, the strengths of Ni and Co were compared with No. 14 ^{* of} Example 1. It was confirmed that the ratio was low. From the results of Table-8, it can be seen that the heat-treated skin also has a high adhesion strength of the boron nitride coating layer as well as the sintered skin, and at the same time, shows a high strength.

[0046]

[Table 9]

[0047]

[Table 10]

[0048]

EFFECTS OF THE INVENTION In all of the boron nitride-coated hard materials of the present invention, the boron nitride-coated hard material has good peeling resistance of the boron nitride-coated layer as compared with the conventional boron nitride-coated hard material, and is almost the same as the boron nitride sintered body. It is clear that it has the same wear resistance and also high strength. Further, it has the advantage that it has a high degree of freedom in shape and can be manufactured in large quantities at low cost, as compared with the case where a boron nitride sintered body is used. Although the case of a cutting tool is shown as an example of the present invention, other various cutting tools, abrasion resistant tools, various machine parts, even when the present invention is applied to a grindstone, etc., good results can be obtained. I can predict enough.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic example of a cutting edge treatment of a tip according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a cross-sectional shape of the work material used in the wet interrupted cutting test of Example 1 of the present invention.

Claims (16)

[Claims] 1. A boron nitride-coated hard material comprising a titanium carbide-based cermet or a titanium carbonitride-based cermet as a base material, and a boron nitride coating layer provided on the surface of the base material. A boron-nitride-coated hard material, characterized in that the proportion of phases is smaller than that in the inside of the base material, or that there is no binder phase in the surface portion of the base material. 2. A boron nitride-coated hard material comprising a titanium carbide-based cermet or a titanium carbonitride-based cermet as a base material, and a boron nitride coating layer provided on the surface of the base, wherein A boron nitride-coated hard material, characterized in that a surface-modifying layer having a high hardness is present. 3. The surface modification layer has a layer thickness of 0.01 to 50.
3. The boron nitride-coated hard material according to claim 2, which has a thickness of 0 μm. 4. A boron nitride-coated hard material comprising a titanium carbide-based cermet or titanium carbonitride-based cermet as a base material, and a boron nitride coating layer provided on the surface of the base, wherein at least a part of the surface of the base is A boron nitride-coated hard material, which is a sintered skin and has a boron nitride coating layer formed on at least a portion of the sintered skin. 5. A boron nitride-coated hard material comprising a titanium carbide-based cermet or a titanium carbonitride-based cermet as a base material and a boron nitride coating layer provided on the surface of the base, at least a part of the surface of the base being baked. The surface of the sintered skin is a binder layer and / or a boron nitride coating layer is formed on at least a portion of the sintered skin from which the surface layer having a higher proportion of the binder phase than the inside is removed. Characteristic boron nitride coated hard material. 6. A boron nitride-coated hard material comprising a titanium carbide-based cermet or a titanium carbonitride-based cermet as a substrate material and a boron nitride coating layer provided on the substrate surface, the substrate being processed into an arbitrary shape. After that, the substrate is heat-treated to form a boron nitride coating layer on at least a part or the whole surface of the substrate having at least a part of the surface properties of the substrate which has been heat-treated. Boron nitride coated hard material. 7. A boron nitride-coated hard material comprising a titanium carbide-based cermet or a titanium carbonitride-based cermet as a substrate material, and a boron nitride coating layer provided on the substrate surface, after the substrate is processed into an arbitrary shape. By heat-treating the base material, at least a part of the surface properties of the base material becomes a heat-treated skin, and at least one of the surface of the heat-treated skin obtained by removing the surface binder phase and / or the surface layer having a higher proportion of the binder phase than the inside. A boron nitride-coated hard material, characterized in that a boron nitride coating layer is formed on the partial surface or the entire surface. 8. The substrate according to claim 1, wherein the binder phase has a substantially continuous or stepwise decrease from the inside toward the surface. Boron nitride coated hard material. 9. The surface of a substrate coated with the boron nitride
Surface roughness is Rmax ^*Is 1.5 μm or more
The method according to any one of claims 1 to 9,
Boron bromide coated hard material. 10. The layer pressure of the boron nitride coating layer is 0.5.
The boron nitride-coated hard material according to any one of claims 1 to 10, wherein the hard material is boron nitride coated hard material. 11. Sintering and / or cermet as a base material
Alternatively, cooling is performed in an atmosphere in which the partial pressure of N ₂ and / or CO and / or CH ₄ is 1 Torr or more, and at least a part of the surface of the obtained sintered body is used as a sintered skin, and at least the sintered skin is further formed. A method for producing a boron nitride-coated hard material, comprising providing a boron nitride coating layer on a part of the surface of. 12. Sintering and cooling of a cermet as a base material is performed in a nitrogen gas atmosphere of 1 Torr or more, and at least a part of the surface of this sintered body is treated with acid and / or metal components leached on the surface. Alternatively, a method for producing a boron nitride-coated hard material, characterized in that a boron nitride coating layer is provided on a part of the surface removed by etching with an alkali. 13. A cermet as a base material is sintered,
After processing into the target shape, at least part of the surface of the substrate is
Heat treatment is performed at a temperature of 00 to 1600 ° C. or higher for 10 minutes to 5 hours, and then cooled in an atmosphere having a partial pressure of CO of 1 Torr or higher to form at least a part of the surface of the base material as a heat treated skin, and further the heat treatment. A method for producing a boron nitride-coated hard material, which comprises providing a boron nitride coating layer on at least a part of the skin surface. 14. A cermet as a base material is sintered,
After processing into a target shape, heat treatment is performed at a temperature of 800 to 1600 ° C. or more for 10 minutes to 5 hours in N ₂ gas of 1 Torr or more, and then cooled to make at least a part of the surface of the base material a heat treated skin, Furthermore, a method for producing a boron nitride-coated hard material, characterized in that a boron nitride coating layer is provided on a partial surface obtained by etching away the metal component leached on the heat-treated skin surface with an acid and / or an alkali. 15. The boron nitride-coated hard according to claim 13 or 14, wherein in the sintering or heat treatment, hot isostatic pressing is performed under a sintering pressure of 10 to 3000 atm. The method of manufacturing the material. 16. The heat treatment step and the step of forming a boron nitride coating layer in the heat treatment are continuously processed in the same processing container or a continuous processing container. A method for producing the hard material coated with boron nitride according to claim 1.