JP2000328170A - Cubic boron nitride-containing hard member and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject member hard to fall, having sufficient densiness of the metallic structure and excellent in wear resistance by composing it of a specified volume % of cubic boron nitride particles, and the balance cemented carbide or cermet and providing it with a coating layer composed of a metal selected from the group VIa elements, Re, or the like, an alloy composed of elements such as the group IVa and Va elements, carbides, or the like. SOLUTION: This member contains 3 to 50 vol.% cubic boron nitride particles and has one or more coating layers of a metal selected from the group VIa elements in the Periodic Table, Re, Os, or the like, an alloy consisting of two or more kinds of elements among the group IVa, Va and VIa elements in the Periodic Table, Al and Si and a compd. of the carbides, nitrides, oxides, or the like, of the group IVa, Va and VIa elements in the Periodic Table, Al and Si or the solid solutions thereof, or the like. The m.p. of this coating layer is >=1300 deg.C, the average particle diameter D of the cubic boron nitride particles is 0.1 to 100 μm, and in the case the thickness of the coating layer is defined as (d), k, i.e., the value of ((0.5D+d)/0.5D)3 is 1.002 to 1.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hard member in which cubic boron nitride particles are contained in a cemented carbide or cermet.

[0002]

2. Description of the Related Art In recent years, the application field of WC-based cemented carbide has been greatly expanded due to its excellent toughness and wear resistance. Further, the application field of the cubic boron nitride sintered body has been increasing due to its wear resistance which is much higher than that of cemented carbide.

[0003] However, the conventional cubic boron nitride sintered body is manufactured by an ultra-high pressure generator, so that the manufacturing cost is high, the shape of the cubic boron nitride sintered body is largely restricted, and its strength and toughness are not good. It was inferior to cemented carbide and could exhibit excellent performance only in limited applications.

On the other hand, Japanese Patent Application Laid-Open Nos. 60-33336 and 2-302371 have proposed manufacturing without using an ultra-high pressure device. This is a method of sintering a cubic boron nitride-containing hard member under pressure and temperature conditions under which cubic boron nitride is not thermodynamically stable.

[0005] However, the cubic boron nitride-containing hard member manufactured without using the ultra-high pressure apparatus has a problem that the structure is not dense enough and the cubic boron nitride particles are easily broken or dropped. There was a problem such as strength. Then, in order to solve the above problem, WC
When sintering cubic boron nitride particles dispersed in a base phase (matrix) of a base cemented carbide,
There has been proposed a method of producing a WC-based cemented carbide in a short time under the condition that a liquid phase is formed (Japanese Patent Laid-Open No. 9-194978). As a result, the structure of the cubic boron nitride-containing hard member is dense, and the cubic boron nitride particles are less likely to break or fall off. Therefore, a cubic boron nitride-containing hard member excellent in abrasion resistance to some extent can be manufactured at low cost. can do.

As a technique for increasing the bonding strength between the cubic boron nitride particles and the matrix, a number of methods for providing a coating layer on the cubic boron nitride particles have been proposed. Have been. However, these proposals do not relate to pure cemented carbides and cermets in which the matrix does not contain a substance having a melting point lower than 1300 ° C., and the denseness of sintered cubic boron nitride-containing hard members is insufficient. As a result, the strength was not sufficient.

[0007] Further, Japanese Patent Application Laid-Open No. 2-302371 discloses a coating layer provided on cubic boron nitride particles, and a raw material of an inorganic material which does not promote the phase transition of cubic boron nitride to a graphite type phase (hexagonal). Sintering has been proposed.
However, as in the present invention, a composite material of a matrix material containing an iron group metal and a cubic boron nitride particle having a catalytic action to convert cubic boron nitride into a hexagonal crystal is converted from cubic boron nitride to a hexagonal crystal. Optimization of coating film quality, coating film thickness, and sintering conditions (particularly, sintering pressure and sintering time) suitable for inexpensive sintering without transfer was insufficient.

Japanese Patent Application Laid-Open Nos. 9-194998 and 5-239585 disclose that a coating layer is provided on diamond particles of the same type as cubic boron nitride, which are stable under high pressure, and that a WC base containing an iron group metal is provided. It has been proposed to produce composite materials with cemented carbides. However, the coating film thickness, coating film quality,
Optimization of the sintering conditions is insufficient, and when used as a wear-resistant member, deterioration of wear resistance due to falling off of cubic boron nitride particles was observed in some cases.

[0009]

Therefore, by further improving the compactness of the structure and improving the bonding force between the cubic boron nitride particles and the matrix made of cemented carbide or cermet, the cubic field can be expanded in a wider field. It is desired to apply hard members containing polycrystalline boron nitride.

According to the present invention, a cubic boron nitride particle which is hardly dropped off when a cemented carbide or cermet is used as a matrix, has a sufficiently dense metal structure and is extremely excellent in wear resistance. It is an object of the present invention to provide a crystalline boron nitride-containing hard member and a method for producing the same.

[0011]

A cubic boron nitride particle;
The balance is made of cemented carbide or cermet, the cubic boron nitride particles are contained in an amount of 3 to 50% by volume, and
Group VIa element, rhenium (Re), osmium (Os),
Rhodium (Rh), iridium (Ir), platinum (Pt)
Alloys composed of two or more elements selected from the group consisting of metals selected from the group consisting of elements IVa, Va and VIa in the periodic table, aluminum (Al) and silicon (Si), and IVa and V in the periodic table
It has at least one coating layer selected from a compound selected from carbides, nitrides, oxides, silicides, borides, or solid solutions of a, VIa group elements, Al and Si. And the melting point of the coating layer is 1300 ° C. or more,
The average particle diameter D of the cubic boron nitride particles is 0.1 to 100.
μm, and the thickness of the coating layer is d ((0.
5D + d) /0.5D) The value K of ³ is 1.002 to 1.5
It is.

In the present application, the cemented carbide means at least one selected from the group consisting of carbides, nitrides, carbonitrides and / or solid solutions of IVa, Va, and VIa group elements mainly composed of WC.
It is a sintered body composed of a binder phase composed of an iron group metal and having a hard phase as a seed. The cermet is TiN, TiC
A hard phase containing at least one selected from the group consisting of carbides, nitrides, carbonitrides, and solid solutions of IVa, Va, and VIa elements, mainly containing any one of N and TiC, and a binder phase composed of an iron group metal. Sinter.

Furthermore, it is preferable that the cubic boron nitride-containing hard member contains a lubricating substance such as WS ₂ , MoS ₂ and graphite. This is because the cubic boron nitride particles of the present invention exist discontinuously like islands in the matrix, and therefore have a higher aggressiveness to the mating material than a material containing more than 50% of cubic boron nitride particles. Higher, but WS
₂ , MoS ₂ , graphite, and other lubricating substances can reduce the aggressiveness of the opponent. Furthermore, the adhesion phenomenon due to the generated wear powder can be prevented, and the wear resistance can be further improved. In general, when WS ₂ and MoS ₂ are contained in a cemented carbide and sintered at a temperature at which the cemented carbide is densified, WS ₂ and MoS ₂ are decomposed and hardly remain in the sintered body. Although not possible, sintering under the conditions of the present invention facilitates the production of a sintered body in which a large amount of these lubricating substances remain. More preferably, the coating treatment performed on the cubic boron nitride particles of the present invention is performed by using WS ₂ , M
By performing the process on oS ₂ , it is possible to protect from the generated liquid phase, so that the residual ratio of WS ₂ and MoS ₂ can be further increased.

Here, the reason why the average particle size of the cubic boron nitride particles is 0.1 to 100 μm is that if the average particle size is smaller than 0.1 μm, it is difficult to obtain the effect of adding the cubic boron nitride particles, This is because it is difficult to form a layer on the cubic boron nitride particles, and when the thickness is larger than 100 μm, when the material of the present invention is used as a wear-resistant material, it is expected that the mating material will be damaged, This is because it is not preferable. Particularly preferred is when the thickness is 30 μm or less. This cubic boron nitride particle size range is suitable for wear and sliding materials such as centerless blades, bearing processing tools, gauges, race centers, suction nozzles, etc., and guides to improve precision machine parts and processing accuracy. Excellent as wear-resistant parts such as pads and can-making tools.

The cubic boron nitride particles preferably have an impurity content of 0.3% by weight or less, preferably 0.2% by weight or less in the cubic boron nitride grains. This is because it is preferable to control deterioration of the cubic boron nitride particles for the present material which is sintered at a temperature at which a liquid phase is formed in the cemented carbide and / or cermet.

That is, if the amount of impurities is more than 0.3% by weight, a mismatch in thermal expansion coefficient between cubic boron nitride and impurities occurs in the cubic boron nitride grains during sintering at a high temperature,
This is because the cubic boron nitride particles are liable to be broken or the wear resistance is reduced due to cracks or strains generated in the particles. The impurities referred to here are Al, Si, Fe, Ni, C
Metal elements such as o, Mg, Li, Mn, Ta, Cu, and Ca. This phenomenon is particularly likely to occur under sintering conditions based on rapid heating and rapid cooling by current heating sintering, which is a preferred production method of the present invention, and is an important control point. It should be noted that although the amount of impurities in the cubic boron nitride particles is preferably as small as possible, cubic boron nitride having a purity higher than 0.01% by weight is expensive, so that it is an inexpensive material which is one of the aims of the present invention. In order for impurities to be 0.01-0.3
It is preferred to use cubic boron nitride particles in weight percent.
Further, after removing the amount of impurities contained in the cubic boron nitride particles of each sintered body by dissolving the hard alloy as a matrix with an acid, the cubic boron nitride particles are dissolved using a molten salt,
Furthermore, an acid was added to form an aqueous solution, and the solution was measured by inductively coupled plasma emission spectrometry. As a result, it was confirmed that there was no significant change from the amount of impurities contained in the raw material.

Further, the content of the cubic boron nitride particles is 3 to
The reason for setting the volume to 45% by volume is that when the content of the cubic boron nitride particles is less than 3% by volume, the effect of improving the wear resistance of the cubic boron nitride-containing hard member is small, and when the content is more than 45% by volume, the content is cubic. This is because the strength of the boron nitride-containing hard member significantly decreases. Particularly preferred is when the content of the cubic boron nitride particles is 10 to 30% by volume. By setting the content of the cubic boron nitride particles to 30% by volume or less and further uniformly dispersing the cubic boron nitride particles, the hardness of the cubic boron nitride-containing hard member is reduced to 2500 or less, preferably 2000 or less in Vickers hardness. Then, the toughness and strength of the cubic boron nitride-containing hard member can be greatly increased. This is because by controlling the content and dispersibility of the cubic boron nitride particles, the hardness of the cubic boron nitride-containing hard member can be made substantially the same as that of the cemented carbide as the matrix. As described above, even when the hardness is set to the same level as that of the cemented carbide matrix, the wear resistance is much higher than that of the cemented carbide or cermet alone, and it is surprising that the wear resistance can approach the wear resistance of ultrahigh-pressure sintered cubic boron nitride. The desired result was obtained. Note that the hardness of the cubic boron nitride-containing hard member is set to 2500 or less in Vickers hardness, preferably 2000 or less, because the Vickers hardness of the superhard matrix is 2500 at the upper limit even when the amount of the binder phase is minimized. In order to achieve excellent toughness and strength as a hard alloy, 2000
This is because the following is preferable.

In the present invention, a cemented carbide is used for the matrix,
Although cermet is used, these materials contain iron group metals, and these metals are useful for improving the toughness and sinterability of the sintered body. However, the iron group metal has a catalytic action of causing a cubic boron nitride to undergo a phase transition to hexagonal, and tends to cause a decrease in hardness of the sintered body. In particular, this catalytic action is remarkable when the iron group metal is liquefied, and it is necessary to prevent the cubic boron nitride particles from directly contacting this liquid phase and to increase the bonding force with the matrix. . Further, cubic boron nitride particles are extremely hard, and if there is a place where they are in direct contact with each other, stress concentration is likely to occur, and the cubic boron nitride particles tend to be a starting point of destruction. Therefore, it is useful to provide a coating layer.

The first requirement is that the coating layer of cubic boron nitride particles does not dissolve at the liquidus temperature. The next requirement is to have good wettability with iron group metals. Excellent wettability means that the bond strength with the iron group metal is high. The coating layer in the present invention is selected from such a viewpoint.

As the coating layer, a group VIa element in the periodic table,
Metal, period selected from Re, Os, Rh, Ir, Pt
Selected from the group IVa, Va, VIa group elements, Al and Si
Alloy consisting of two or more elements, IVa and V in the periodic table
a, VIa group element, Al, Si carbide, nitride, oxidation
Selected from materials, silicides, borides or solid solutions thereof
Compounds, especially Cr, W, Mo, Cr-Mo, T
i-Ta, Ti-Mo, Nb-V, Ti-Al-V, T
iC, TiN, Al_TwoO_Three, SiC, WC, MoSi _Two,
Metals, alloys such as TiBN, TiAlN, TiZrN,
Compounds are preferred. These materials have a melting point or decomposition temperature
Temperature is 1300 ° C or higher, and the sintering temperature is higher than the melting point of the coating layer.
It is important to lower

Next, the reason for introducing the value (K) of ((0.5D + d) /0.5D) ³ is that many proposals have been made to provide a coating layer on cubic boron nitride particles as described above. I have. However, in order to further enhance the bonding strength and sinterability between the cubic boron nitride particles and the cemented carbide or cermet matrix and the wear resistance of the cubic boron nitride-containing hard member, one cubic boron nitride particle is required. It was found that it was necessary to set the optimum coating layer volume according to the volume of the coating layer. This is because the content of the cubic boron nitride particles in the hard member of the present invention is less than 50%, and the cubic boron nitride particles are contained in the matrix of the cemented carbide or cermet as a matrix during liquid phase sintering. This is particularly important because it is in a floating state.

Therefore, K, which is a value obtained by dividing the volume of the cubic boron nitride particles including the thickness of the coating layer by the volume of the cubic boron nitride particles, is introduced, and the numerical value is optimized. The reason for the numerical limitation is that if K is smaller than 1.002, the effect of the coating layer is difficult to obtain, so that the holding power with the matrix cannot be secured. If K is larger than 1.5, a uniform coating layer is obtained. In addition to the difficulty, the characteristics tend to vary, and the thick coating layer hinders the increase in the packing density of the cubic boron nitride particles and the matrix raw material. Limited to. Particularly preferred value of K is from 1.01 to 1.2.

As a method for forming such a coating layer, there are a physical vapor deposition method such as a sputtering method and an ion plating method, a chemical vapor deposition method, a plating method, and a dipping method. Note that the bridging between cubic boron nitride particles having a thick coating layer may lower the packing density of the cubic boron nitride particles and the matrix material. This phenomenon is likely to occur when the content of the cubic boron nitride particles is large, and when the content of the cubic boron nitride particles is too large, it is an obstacle in producing a hard member having excellent wear resistance. Become.

Therefore, the content of cubic boron nitride is 10
When it is で 30% by volume, particularly excellent wear resistance can be exhibited. This is because if it is less than 10% by volume, the effect of improving the wear resistance is small, and if it is more than 30% by volume, it becomes difficult to densify for the above-mentioned reason, and the strength of the material is significantly reduced.

The cemented carbide and / or cermet of the present invention is preferably sintered at a sintering temperature that produces a liquid phase. The preferred sintering temperature is 1300 to 1450 ° C, and particularly preferred is 1300 to 1400 ° C. Further, it is preferable that the sintering temperature is maintained for 10 seconds or more and 30 minutes or less, and that the sintering is performed by current pressure sintering under the conditions of a pressure of 5 to 100 MPa.

Here, the reason why the holding time at the sintering temperature at which the liquid phase is generated is set to 10 seconds or more and 30 minutes or less is that if the holding time is shorter than 10 seconds, densification is insufficient, and If the length is too long, the transformation of cubic boron nitride to hexagonal boron nitride is likely to occur. Particularly preferred is 1 minute or more and 10 minutes or less. The pressure is preferably 5 to 100 MPa. This is because if the pressure is lower than 5 MPa, the matrix of the cubic boron nitride-containing hard member is less likely to be densified, and if the pressure is higher than 100 MPa, a special sintering method is required and the production cost increases. .

When the current pressure sintering is performed using a rectangular pulse current having a current ON time of 1 to 100 msec and a current OFF time of 1 msec or more, very dense cubic boron nitride particles are obtained. A cubic boron nitride-containing hard member that is less likely to fall off can be obtained.

In the coating layer, Co, Ni, W, Ti,
When at least one element selected from C, B and N is diffused, the bonding strength between cubic boron nitride and the hard alloy as the matrix is improved. In particular, the effect of diffusion of Co and Ni is great, and these diffusions can be easily obtained by current pressure sintering using a rectangular pulse current of 1 to 100 msec.
In the present application, sintering is preferably performed using a liquid phase. However, components of the liquid phase, such as Co and Ni, and W and T dissolved therein are used.
i, C and N diffuse into the coating layer. B and N also diffuse from cubic boron nitride. Co, Ni, W, Ti,
It is desirable that the diffusion of C, B, and N occurs over the entire thickness of the coating layer.

The cubic boron nitride-containing hard member obtained in the present application is worked after sintering and joined to another cemented carbide, steel, or the like for practical use. However, it contains chemically stable cubic boron nitride particles, and the coating layer on the surface of the particles is removed by processing, so that brazing or the like becomes difficult. In particular, it is remarkable when the cubic boron nitride content is large. Therefore, the inventor further studied and found a method of directly contacting the raw material of the cubic boron nitride-containing hard member and the cemented carbide or steel during sintering and sintering to join them simultaneously with sintering.

When the cubic boron nitride-containing hard member is joined to at least one of a WC-base cemented carbide and steel, a compressive residual stress is generated in the cubic boron nitride-containing hard member due to a coefficient of thermal expansion. As well as being toughened, brazing and welding work become unnecessary or easy, and the application field of the cubic boron nitride-containing hard member according to the present invention can be expanded.

In addition, diamond or diamond-like carbon (hereinafter referred to as Diamond Lik) is used for the hard member.
e carbon is hereinafter referred to as DLC. ), At least one coating layer of cubic boron nitride is formed with cubic boron nitride particles in the hard member as nuclei, so that it has extremely excellent adhesion. As a result, the entire hard member is coated with at least one of diamond, DLC, and cubic boron nitride, thereby exhibiting excellent wear resistance and lubricity. In particular, when coated with DLC, the coating layer is smooth and excellent in lubricity, so that peeling does not easily occur, and very excellent performance as a wear-resistant member can be obtained. This excellent adhesion is achieved by the fact that the bonding force between the cubic boron nitride particles in the hard member and the matrix made of the cemented carbide and / or cermet is enhanced by the present invention, so that particularly excellent performance can be obtained. It is.

Incidentally, using the cubic boron nitride particles,
When the carbide, nitride or carbonitride of WC and / or Ti and the binder phase metal composed of the iron group metal are 100% by weight, the content of the iron group metal is 2 to 50% by weight,
It is excellent because it has excellent toughness, strength, hardness, sinterability, and heat crack resistance as a matrix for binding cubic boron nitride particles. It is particularly preferable that the content of the iron group metal is 2 to 20% by weight. There is one time. In particular, when a matrix having this amount of iron group metal is used, excellent wear resistance can be obtained in an environment where a high pressure is applied.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific examples of the present invention and other comparative examples will be described. (Test Example 1) First, Examples 1 to 5 and Comparative Examples 1 to 4 were combined.
Is shown. A WC powder having an average particle size of 5 μm, a Cr ₃ C ₂ powder having an average particle size of 1 μm, and a Co powder having an average particle size of 2 μm were prepared.
The WC powder, the Co powder, and the Cr ₃ C ₂ powder were weighed so that the amount of Co became 10% by weight and the amount of Cr ₃ C ₂ became 0.7% by weight, and the powders were pulverized and mixed using an attritor. -0.
A 7 wt% Cr ₃ C ₂ -10 wt% Co powder was obtained.

Next, cubic boron nitride particles having an average particle size of 0.5 μm were coated with TiN by a PVD method. The value of K (coating layer thickness) was 1.001 in Comparative Example 1, 1.002 in Example 1, 1.01 in Example 2, and 1.0 in Example 3.
2, the coating was made to be 1.3 in Example 4, 1.4 in Example 5, 2.0 in Comparative Example 2, and 3.4 in Comparative Example 3. The cubic boron nitride particles used had a cubic boron nitride content of 0.3% by weight. And
The WC-0.7% by weight Cr ₃ C ₂ -10% by weight C so that the coated cubic boron nitride particles become 25% by volume.
o The powder was mixed using a ball mill.

The powder prepared in this way is 30 m in inner diameter.
m, and sintered under pressure by applying a direct current while applying a pressure of 30 MPa in a vacuum of 0.01 Torr or less. 1320 ° C for 6 minutes
Temperature, hold at that temperature for 3 minutes, 40 ° C / min
Cooled at the speed. The size of the sintered body thus obtained is a disk-shaped sintered body having a diameter of 30 mm and a thickness of 10 mm.
It had good appearance without cracking.

After removing the black scale of these sintered bodies, the specific gravity of each of Examples 1 to 5 and Comparative Examples 1 to 3 was measured by the Archimedes method, and the ratio to the theoretical density was determined. Example 1
5 and Comparative Example 1 had a ratio of 9 to the theoretical density.
Although the densities were 5% or more, the samples of Comparative Examples 2 and 3 exhibited low densities of 89% and 79%, respectively, relative to the theoretical density.

Next, a sintered body having a length of 10 mm, a width of 20 mm and a height of 10 mm was cut out from the sintered bodies of Examples 1 to 5 and Comparative Examples 1 to 3, and this sintered body was made of SiC having an average particle diameter of 20 μm.
The powder was sandblasted at a pressure of 5 kg / cm ² for 60 minutes, and the amount of wear was measured.

As Comparative Example 4, the same WC-0.7 wt% Cr ₃ C ₂ -10 as in Examples 1 to 5 and Comparative Examples 1 to 3 was used.
% By weight of a Co powder material (not including cubic boron nitride particles) under current-pressure sintering under the same conditions.
Table 1 shows the wear ratios of the sintered bodies of Examples 1 to 5 and Comparative Examples 1 to 3 when 0 was set.

[0039]

[Table 1]

Further, a test piece having a length of 3 mm, a width of 4 mm and a height of 12 mm was cut out from the sintered bodies of Examples 1 to 5 and Comparative Examples 1 to 4 using a wire cutting apparatus and Hiraken, and subjected to three-point bending bending. A force test was performed. The results are also shown in Table 1.

From the results in Table 1, it is found that cubic boron nitride particles
It was confirmed that Examples 1 to 5 coated with TiN having a value of 1.002 to 1.4 exhibited excellent wear resistance and strength. Above all, Examples 2-3 in which the K value is 1.01-1.2
Showed particularly good performance.

The wear portion of the sample for which the wear resistance was evaluated was cut vertically, and the wear portion was evaluated in detail.
In the sample of Comparative Example 1 having a value of 1.001, a large amount of hexagonal boron nitride was observed, and in Comparative Example 2 having a K value exceeding 1.4,
In the sample of No. 3, a trace was observed as if the aggregates were dropped off in a lump. This was considered to be due to the fact that the agglomerates of the cubic boron nitride particles were liable to fall off due to insufficient densification, and the wear resistance was reduced.

(Test Example 2) In Examples 6 and 7, powders having the same composition and the same TiN coating layer thickness as those of Examples 2 and 3 were used.
It was filled in a 0 mm graphite mold, and subjected to current pressure sintering with a rectangular pulse current having an ON time of 80 msec and an OFF time of 20 msec while applying a pressure of 30 MPa in a vacuum of 0.01 Torr (Torr) or less. Heating pattern is 1 in 6 minutes
Raise the temperature to 320 ° C, hold at that temperature for 3 minutes,
/ Min.

The wear resistance and bending strength of the sintered bodies of Examples 6 and 7 were measured in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 4. The results are shown in Table 2. It was found that the sintered bodies of Examples 6 and 7 exhibited better wear resistance and strength than Examples 2 and 3.

[0045]

[Table 2]

In order to investigate the reason, Examples 2, 3,
TEM (Transmission) of 6 and 7 sintered bodies
Electron Microscope) A sample for observation was prepared, and the state of the TiN coating layer was evaluated by EDX. As a result, Co diffused in the TiN coating layers of Examples 6 and 7 over the entire thickness of the coating layer.
It was considered that o increased the bonding force between the cubic boron nitride particles and the matrix of the WC-based cemented carbide, and exhibited excellent wear resistance.

(Test Example 3) In Examples 8 to 14, cubic boron nitride particles having an average particle size of 9 μm were prepared.
Was prepared in the same manner as in Test Example 1 by preparing a cubic boron nitride powder (K value 1.09) coated with 0.15 μm in thickness and a powder (K value 4.63) coated with 3 μm of W. W
In C-0.7 wt% Cr ₃ C ₂ -10 wt% Co powder, cubic boron nitride particles are contained in 0, 5, 10, 15, 20, 30,
It was blended so as to be 40% by volume and 50% by volume, and particularly mixed by a ball mill for a long time so that the dispersibility of the cubic boron nitride particles was improved. Note that, as the cubic boron nitride particles, cubic boron nitride containing 0.2% by weight of impurities in the grains was used.

This powder was prepared in the same manner as in Test Example 1,
It was filled in a 0 mm graphite mold, and was subjected to current pressure sintering with a rectangular pulse current having an ON time of 99 msec and an OFF time of 1 msec while applying a pressure of 40 MPa in a vacuum of 0.01 Torr (Torr) or less. Heating pattern is 1 in 10 minutes
Heat up to 380 ° C, hold at that temperature for 1 minute,
/ Min. Test Example 1 shows the amount of wear of the sintered bodies (Examples 8 to 14 and Comparative Example 5) thus manufactured.
The measurement was performed in the same manner as described above. The Vickers hardness of these sintered bodies was measured under a load of 50 kg.

Table 3 shows the results. From the results in Table 3,
The sample having a K value of 1.09 is more excellent in wear resistance than the sample having a K value of 4.63, and the sample having a K value of 1.09 has a cubic boron nitride particle content of 10%. ~ 30% by volume
Examples 9 to 12 were found to exhibit particularly excellent wear resistance. When the content of the cubic boron nitride particles is 3
The Vickers hardness of the samples of Examples 8 to 12 in which the content was 0% by volume or less was about 1550 kg / mm ² , which was equivalent to the hardness of Comparative Example 5 containing no cubic boron nitride particles. Therefore, impact was applied 20 times with an energy of 10 joules (J) using a carbide ball having a diameter of 20 mm from the perpendicular direction to the ground surfaces of the sintered bodies of Examples 8 to 14 and Comparative Example 5. As a result, while Examples 13 and 14 were severely damaged, the sintered bodies of Examples 8 to 12 and Comparative Example 5 did not show any chipping.

[0050]

[Table 3]

(Test Example 4) Next, Example 15 will be described. That is, the diameter is 100 m and the material is SCM435.
A steel disc having a thickness of 10 mm and a thickness of 10 mm was inserted into a graphite mold having an inner diameter of 100 mm, and WC-30 wt% Co powder was filled thereon. Then, the cubic boron nitride powder (K value: 1.06), in which cubic boron nitride particles having an average particle diameter of 100 μm are coated with TiC to a thickness of 0.8 μm, has a volume ratio of 25% by volume.
-20% by weight Co powder mixed with the WC-3
0 wt% Co powder and filled to 0.01 Torr (To
rr) While applying a pressure of 20 MPa in the following vacuum,
Electric current pressing sintering was performed with a rectangular pulse current having an ON time of 99 msec and an OFF time of 1 msec. The cubic boron nitride particles used had a cubic boron nitride content of 0.05% by weight in the grains.

In the heating pattern, the temperature was raised to 1340 ° C. in 30 minutes, kept at that temperature for 10 minutes, and cooled at a rate of 20 ° C./min. The disc-shaped sintered body thus obtained has a steel part thickness of 10 mm, a WC-30 wt% Co sintered body part thickness of 5 mm, and a cubic boron nitride particle-containing cemented carbide member thickness. Was 5 mm. As a result of mirror-polishing the cross section of the test piece and observing it with an optical microscope, it was found that there was no crack between the layers and the layers were firmly joined.

In the following Example 16, only the powder material having the same composition as that of the layer of the cubic boron nitride particle-containing carbide member of Example 15 was directly inserted into a graphite mold having a diameter of 100 mm, and the same firing as in Example 15 was performed. A sintered body having a thickness of 15 mm was produced by a knotting method.

Next, the black scale on the upper surface (corresponding to the portion containing cubic boron nitride particles in Example 15) of the sintered bodies of Examples 15 and 16 was removed using a diamond grindstone. Using a carbide ball having a diameter of 20 mm from the vertical direction, impact was applied 50 times with an energy of 10 joules (J).

As a result, it was found that although Example 15 had small chips, it was not severely damaged, whereas Example 16 was severely damaged. This is because in Example 15, since the layer of the superhard portion was bonded to steel, the compression residual of about 500 MPa was added to the WC of the surface of the layer of the superhard member containing cubic boron nitride in view of the coefficient of thermal expansion. Although stress was introduced and toughened, and the propagation of the generated cracks was stopped by the lower layer of the sintered layer of the tough cemented carbide, the material did not break as a result. It was considered that the joint was severely damaged because there was no bonding with the steel and no compressive residual stress was generated on the surface.

Test Example 5 The test piece of Example 15 was further subjected to PVD on the layer of the superhard member containing cubic boron nitride particles.
(Physical Vapor Deposition
n) The test piece of Example 17 coated with DLC to a thickness of 3 μm by the method, CVD (Chemical Vapor De)
A test piece of Example 18 in which cubic boron nitride was coated at a thickness of 3 μm by the position method was produced. WC-3 wt% Co powder produced in the same manner as in Test Example 1 was used in Test Example 4.
Under the conditions described above, current pressure sintering was performed to obtain a sample of Comparative Example 6.

Then, the samples of Examples 15, 16, 17, 18 and Comparative Example 6 were subjected to a pin-on-disk tester with a mating material of SUJ2 ball and a rotation speed of the test piece of 3 m.
/ Min, the pressure was set to 10 Newtons (N), and the wear amount and the dynamic friction coefficient were measured in the atmosphere for 60 minutes. The wear ratios and the dynamic friction coefficients of Examples 15 and 16 were the same. In addition, the measurement result of the abrasion amount was represented by the abrasion amount ratio with the abrasion amount of the test piece of Comparative Example 6 being 100.

[0058]

[Table 4]

Table 4 shows the results. From the results in Table 4,
Examples 17 and 18 coated with DLC and cubic boron nitride
Shows very good wear resistance and very low coefficient of kinetic friction.

(Test Example 6) TiCN having an average particle size of 5 μm
-20% by weight WC-10% by weight TaC solid solution powder was mixed with Ni and Co powders having an average particle size of 1 μm so as to be 8% by weight, respectively, and the powder was mixed and pulverized by an attritor. Next, a coating layer having a K value of 1.12 shown in Table 5 was provided on cubic boron nitride particles having an average particle size of 5 μm. That is, Example 19 is TiCN, Examples 20 and 21 are Mo,
In Example 22, Nb was coated at a coating thickness of 0.1 μm.

[0061]

[Table 5]

The cubic boron nitride particles thus coated were added to and mixed with the above mixed powder so that the volume became 30% by volume. This powder was sintered under the same conditions as in Test Example 2 under a reduced-pressure nitrogen atmosphere to produce Examples 19 to 22. Further, Comparative Example 7 consisting of a cermet produced by sintering only the mixed powder was also produced. Test samples were prepared from these sintered bodies in the same manner as in Test Example 1, and a wear test was performed. As shown in Table 5, the wear amount ratio was 4 in Example 19 and 6 in Examples 20 to 22, indicating that excellent wear resistance was obtained even when Mo and Nb were coated. I confirmed that I can do it.

(Test Example 7) A WC powder having an average particle diameter of 5 μm was mixed with a Co powder having an average particle diameter of 2 μm so as to be 5% by weight, and the powder was mixed and pulverized by an attritor.
20% by volume of the coated cubic boron nitride particles used in Example 19 of Test Example 6 were mixed with this mixed powder,
mm of graphite mold. However, a disc of cemented carbide or steel shown in Table 6 was previously spread on the graphite mold in the same manner as in Test Example 4.

[0064]

[Table 6]

That is, in Example 23, WC-15% by weight Co cemented carbide powder was used. In Example 24, the second, first and WC-35% by weight were coated on a third disk, ie, SCM415 steelmaking.
Co cemented carbide powder and WC-15 wt% Co cemented carbide powder are stacked and filled in this order, and WC-5 wt% Co obtained by mixing the above 20% by volume cubic boron nitride particles thereon.
Filled with cemented carbide powder.

Then, while applying a pressure of 40 MPa in a vacuum of 0.01 Torr or less, the ON time is set to 8 hours.
Examples 23 and 24 and Comparative Example 8 (only cubic boron nitride-containing superhard powder) were subjected to current pressure sintering with a rectangular pulse current having 0 msec and OFF time of 20 msec. The heating pattern is 8
The temperature was raised to 1340 ° C. for 1 minute, kept at that temperature for 5 minutes, and cooled at a rate of 40 ° C. per minute.

The materials of Examples 23, 24 and Comparative Example 8, which were the sintered bodies produced in this manner, were joined to a member made of SCM415 using a metal brazing. Example 23
Is WC-15 wt% Co cemented carbide surface, Example 2
The material No. 4 is obtained by joining the surface of the SCM 415 to a member made of the SCM 415 using a metal brazing. As a result, the material of Comparative Example 8 was cracked and could not be joined well, but the materials of Examples 23 and 24 could be joined without cracking.

The cubic boron nitride-containing layers of the materials of Examples 23 and 24 were subjected to compressive residual stress shown in Table 6, and a lower layer of a tough cemented carbide layer having a large thermal expansion coefficient was laminated. As a result, it is considered that the thermal stress generated between the member and the SCM415 member at the time of brazing was alleviated, and the occurrence of thermal cracks was prevented. Therefore, in order to increase the coefficient of thermal expansion of the cubic boron nitride-containing hard member, it is desirable to laminate and simultaneously sinter at least one of cemented carbide powder or steel having a large coefficient of thermal expansion.

(Test Example 8) WS _{2 having} an average particle size of 100 μm,
MoS ₂ , WC with an average particle size of 5 μm, Co with an average particle size of 1 μm
Prepare powder, cubic boron nitride particles having an average particle size of 30 μm,
WC-10 wt% Co-10 wt% (WS ₂ or MoS ₂₎
-20% by volume cubic boron nitride was blended and mixed by a ball mill to prepare a powder for sintering. These powders were sintered under electric pressure under the conditions of Test Example 4 to obtain a powder of Example 25 (WS ₂
) And Example 26 (containing MoS ₂ ).
Similarly, a powder having a composition of WC-10% by weight, Co-20% by volume, cubic boron nitride was prepared, and was subjected to current pressure sintering under the conditions of Test Example 4 to produce a sintered body of Example 27. did.

Then, the samples of Examples 25, 26 and 27 were subjected to a pin-on-disk tester using an Al ball as a counterpart material, a rotation speed of a test piece of 3 m / min, and a pressure of 10 Newton (N). The wear amount and the dynamic friction coefficient were measured in the atmosphere for 60 minutes. In addition, the measurement result of the abrasion amount was represented by the abrasion amount ratio with the abrasion amount of the test piece of Example 27 being 100.

[0071]

[Table 7]

Table 7 shows the results. From the results in Table 7,
It is evident that Examples 25 and 26 with the addition of WS ₂ and MoS ₂ show very good wear resistance and a low coefficient of dynamic friction.

[0073]

According to the present invention, an average particle size of 0.1 to 10 having a coating film of an appropriate thickness in a matrix of cemented carbide or cermet.
0μm dispersed cubic boron nitride particles are produced by current pressure sintering under conditions where a liquid phase is formed in the cemented carbide and / or cermet, so that the cubic boron nitride particles are less likely to fall off and wear resistant. A cubic boron nitride-containing hard member having excellent properties can be provided.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B22F 7/00 C01B 21/064 M 7/08 C22C 29/02 A C01B 21/064 29/04 B C22C 29 / 02 B22F 3/14 101B 29/04 3/24 102A

Claims (14)

[Claims] 1. A cubic boron nitride particle and a balance of cemented carbide or cermet, wherein the cubic boron nitride particle is contained in an amount of 3 to 45 vol.
Rhenium (Re), Osmium (Os), Rhodium (R
h), a metal selected from iridium (Ir), platinum (Pt), two or more elements selected from the group IVa, Va, VIa elements of the periodic table, aluminum (Al), and silicon (Si). Selected from alloys, IVa, Va, Group VIa elements of the periodic table, carbides, nitrides, oxides, silicides, borides or solid solutions of aluminum (Al) and silicon (Si) It has at least one coating layer, the melting point of the coating layer is 1300 ° C. or more, and the average particle diameter D of the cubic boron nitride particles is 0.1 to 1
When the thickness of the coating layer is d, the value K of ((0.5D + d) /0.5D) ³ is 1.002.
Cubic boron nitride, wherein the cubic boron nitride is produced by a sintering method under metastable conditions. 2. The cubic boron nitride-containing hard member according to claim 1, wherein the value of K is 1.01 to 1.2. 3. The cubic boron nitride-containing hard member according to claim 1, wherein the amount of impurities contained in the cubic boron nitride particles is 0.3% by weight or less. 4. An average particle diameter of the cubic boron nitride particles is 30.
The cubic boron nitride-containing hard member according to claim 1, wherein the thickness is not more than μm. 5. The coating layer is made of cobalt (Co), nickel (Ni), tungsten (W), titanium (Ti),
The cubic boron nitride-containing hard member according to claim 1, wherein the hard member contains at least one of carbon (C), boron (B), and nitrogen (N). 6. A cubic boron nitride particle having a content of 10
The cubic boron nitride-containing hard member according to claim 1, wherein the content is 30 to 30% by volume. 7. The cubic boron nitride-containing hard member has a cubic boron nitride particle content of 30% by volume or less, and
The cubic boron nitride-containing hard member according to claim 1, wherein the Vickers hardness is 2500 or less. 8. The cubic boron nitride-containing hard member includes:
WS _2, MoS _2, cubic boron nitride-containing rigid member according to claim 1, characterized in that lubricating material such as graphite is contained. 9. The cubic boron nitride-containing hard member is made of WC
The cubic boron nitride-containing hard member according to claim 1, wherein the hard member is bonded to at least one of a base cemented carbide and steel. 10. The cubic boron nitride-containing hard member,
Diamond, diamond-like carbon (DL
3. The cubic boron nitride-containing hard member according to claim 1, wherein the hard member is coated with at least one of C) and cubic boron nitride. 11. Except for the cubic boron nitride particles, W
C and or Ti carbides, nitrides or carbonitrides;
The cubic boron nitride-containing hard member according to claim 1, wherein the content of the iron group metal is 2 to 20% by weight when the binder phase metal composed of the iron group metal is 100% by weight. . 12. The cubic boron nitride particles are added with VIa in the periodic table.
Group element, metal selected from rhenium (Re), osmium (Os), rhodium (Rh), iridium (Ir), platinum (Pt), group IVa, Va, group VIa element of periodic table, aluminum (Al), 2 selected from silicon (Si)
Alloys composed of more than one element, IVa, Va, VI in the periodic table
coating at least one selected from a group a element, aluminum (Al), silicon (Si) carbide, nitride, oxide, silicide, boride or a solid solution thereof; The average particle diameter D of the boron nitride particles is 0.
1 to 100 μm, and the thickness of the coating layer is ((0.5D + d) /0.5D) ^{3 where} d is the thickness of the coating layer.
Of cubic boron nitride particles coated so that the value K is 1.002 to 1.5, tungsten carbide (WC) powder, titanium nitride (TiN) powder, titanium carbonitride (TiCN) Powder and at least one hard compound selected from titanium carbide (TiC) powder and a binder phase metal powder composed of an iron group metal are mixed and molded, and a temperature higher than a temperature at which the iron group metal forms a liquid phase and cubic A method for producing a cubic boron nitride-containing hard member, wherein boron nitride is produced by a sintering method under metastable conditions. 13. The method according to claim 1, wherein the sintering is performed at a temperature of 1300 to 1450.
° C, the holding time is 10 seconds or more and 30 minutes or less,
The method for producing a cubic boron nitride-containing hard member according to claim 12, wherein current-pressure sintering is performed at 100 to 100 MPa. 14. The method of claim 1, wherein the current-pressure sintering is performed for 1 to 100 msec.
c. A rectangular pulse current of c is used.
13. The method for producing a cubic boron nitride-containing hard member according to item 13.