JP2000144299A - Diamond-containing hard member and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the bonding strength between diamond and matrix composed of cemented carbide or cermet to a greater extent by specifying the content and size of diamond particles and also specifying the melting point and thickness of a coating layer which consists of one or more kinds selected from metals such as the group VIa elements, alloys of two or more elements among the group IVa, Va, and VIa elements or the like, and the carbides, nitrides, etc., of the group IVa, Va, and VIa elements, etc. SOLUTION: This hard member contains 3-50 vol.% of diamond particles and has a coating layer of one or more kinds selected from the following: metals consisting of the group VIa elements, Re, Os, Rh, Ir, and Pt; alloys consisting of two or more elements among the group VIa, Va, IVa, and VIa elements, Al, and Si; the carbides, nitrides, oxides, silicides, and borides of the above elements or solid solutions thereof. Moreover, the melting point of the coating layer is >=1300 deg.C and the average size D of the diamond particles is >100-3000 μm, and the thickness (d) of the coating layer is regulated so that it is <=15 μm and the value K of ((0.5D+d)/0.5D)3 becomes >=1.002. The hard member is manufactured by a sintering process under the condition that diamond is metastable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard member in which diamond particles are contained in a hard metal or a 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 diamond sintered body has been increased due to the wear resistance which is much higher than that of the cemented carbide.

[0003] However, the conventional diamond sintered body is manufactured by a large-sized ultra-high pressure generator, so that the manufacturing cost is high and the shape of the diamond sintered body is largely restricted. Its strength and toughness were inferior to cemented carbides, and it was only in limited applications that it could exhibit excellent performance.

On the other hand, Japanese Patent Application Laid-Open Nos. Hei 5-24922 and Hei 7-34157 propose manufacturing without using an ultra-high pressure device. This is a method of sintering a diamond-containing hard member under pressure and temperature conditions under which diamond is not thermodynamically stable.

[0005] However, the diamond-containing hard member manufactured without using the ultrahigh-pressure apparatus has a problem that the structure is not dense enough and the diamond particles easily fall off. Then, in order to solve the above-mentioned problems, when sintering diamond particles dispersed in a parent phase (matrix) of a WC-based cemented carbide by energization and pressurization, a liquid phase is generated in the WC-based cemented carbide. A method of manufacturing under conditions (Japanese Patent Application Laid-Open No. 9-194978) has been proposed. Thereby, the structure of the diamond-containing hard member is somewhat dense and the diamond particles hardly fall off, so that a diamond-containing hard member excellent in wear resistance can be manufactured at low cost.

As a technique for increasing the bonding force between the diamond particles and the matrix, a number of methods for providing a coating layer on the diamond particles have been conventionally proposed, and they are particularly used as a diamond grinding wheel material. However, these proposals do not consist of a pure WC-based cemented carbide whose matrix does not contain any substance having a melting point lower than 1300 ° C., and that the sintered diamond-containing hard members have insufficient densities. As a result, the strength was not sufficient.

Further, Japanese Patent Application Laid-Open No. Hei 2-302367 discloses that a diamond particle is provided with a coating layer, and that a diamond raw material which does not promote the phase transition to a graphite phase is sintered under a metastable condition. Has been proposed. However, as in the present invention, in order to inexpensively sinter a composite material of diamond particles and a matrix material containing an iron group metal having a catalytic action to convert diamond to graphite without causing phase transition of diamond to graphite. Suitable coating film quality, coating film thickness, sintering conditions (especially sintering pressure,
Optimization for sintering time) was insufficient and the compactness was low. Japanese Patent Application Laid-Open No. Hei 5-24922 also proposes providing a coating layer on diamond particles and sintering the diamond under metastable conditions. However, as in the present invention, the diamond is transformed into graphite. Optimization of coating film thickness, coating film quality, and sintering conditions suitable for inexpensively sintering a composite material of a matrix material and a diamond particle containing an iron group metal having a catalytic action without graphitizing diamond. It was not enough. In addition, no measure has been taken to address the problems that occur when using the electric heating sintering, which is the preferred production method of the present invention.

Japanese Patent Application Laid-Open No. 9-194978 discloses that Ir, Os, Pt, Re, and R are added to diamond particles using a WC-based cemented carbide containing an iron group metal as a matrix.
It is disclosed that a coating layer made of at least one metal selected from h, Cr, Mo, and W is provided. This is to expect the coating layer to function as a barrier when a liquid phase is formed in the matrix of the WC-based cemented carbide, and to improve wear resistance and the like. Japanese Patent Application Laid-Open No. Hei 5-239585 discloses a method in which a coating layer thicker than 1 μm is provided on diamond particles smaller than 100 μm and a composite material with a WC-based cemented carbide containing an iron group metal is hot-pressed or gas-pressure sintered. It is described that the sintered body is made dense by performing the method. However, the optimization of coating film quality, coating film thickness, and sintering conditions in these proposals was insufficient, and when used as a wear-resistant member, there were cases where deterioration of wear resistance due to falling off of diamond particles was observed. .

[0009]

Therefore, by further improving the compactness of the structure and further improving the bonding force between the diamond particles and the matrix made of cemented carbide or cermet, the diamond-containing hard material can be used in a wider field. It is desired to apply the member.

[0010] The present invention relates to a diamond-containing hard member which is extremely hard to fall off when a cemented carbide or a cermet is used as a matrix, has a sufficiently dense structure, and is extremely excellent in wear resistance. It is an object of the present invention to provide a manufacturing method thereof.

[0011]

Means for Solving the Problems Diamond particles and the balance are made of cemented carbide or cermet, the diamond particles are contained in an amount of 3 to 50% by volume, and the periodic table VI
Group a element, metal selected from Re, Os, Rh, Ir, Pt, Group IVa, Va, Group VIa element in periodic table, Al,
Alloys of two or more elements selected from Si, elements of group IVa, Va, VIa in the periodic table, carbides, nitrides, oxides, silicides, borides of Si and Si or solid solutions thereof; At least one coating layer selected from the above compounds. And the melting point of the coating layer is 1300 ° C.
And the average diameter D of the diamond particles is 1
When the thickness of the coating layer is d, where the thickness of the coating layer is d ((0.
The value K of 5D + d) /0.5D) ³ satisfies 1.002 or more and is 15 μm or less.

In the present application, the cemented carbide is mainly composed of WC, and is mainly composed of carbides, nitrides, and the like of elements IVa, Va, and VIa.
It is a sintered body composed of a binder phase composed of iron group metal, in which at least one selected from carbonitrides and / or solid solutions thereof is a hard phase. The cermet is TiN,
IVa, V mainly using either TiCN or TiC
a, a sintered body comprising a hard phase containing at least one selected from carbides, nitrides, carbonitrides and / or solid solutions of group VIa elements, and a binder phase composed of an iron group metal. Further, W is contained in the diamond-containing hard member.
It is preferable that a lubricating substance such as S ₂ , MoS ₂ , and graphite is contained. This is because the diamond particles of the present invention exist discontinuously in the matrix like islands.
Although the aggressiveness to the counterpart material is higher than that of a material containing more than 0% of diamond particles, WS ₂ , MoS ₂ ,
This is because the inclusion of a lubricating substance such as graphite 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. Normally, when WS ₂ and MoS ₂ are contained in a cemented carbide and sintered at a temperature at which the cemented carbide is densified, W 2
Although S ₂ and MoS ₂ are decomposed and hardly remain in the sintered body, sintering under the conditions of the present invention makes it possible to produce a sintered body in which a large amount of these lubricating substances remain. It will be easier. More preferably, by providing the diamond particles of the present invention with a coating treatment for WS ₂ and MoS ₂ , the residual ratio of WS ₂ and MoS ₂ can be further increased.

Here, the average diameter of the diamond particles is 1
The reason why it is larger than 00 μm and 3000 μm or less is as follows.
If it is smaller than 100 μm, it is difficult to make use of the wear resistance of the single crystal diamond particles to the hard member,
On the other hand, if the diameter is larger than 3000 μm, the decrease in the strength of the single crystal diamond particles themselves increases. If the average particle size of the diamond particles is within this range, it is suitable for cutting and processing stones and concrete, for urban development tools such as construction drilling tools, mining tools, and oil drilling tools.

As the diamond particles, the amount of impurities (metals, minerals, etc.) excluding carbon in the diamond particles is 0.3%.
What is less than 0.2 weight% is preferable. This is because the material is sintered at a temperature at which a liquid phase is formed in the cemented carbide and / or cermet, which is preferable in controlling the deterioration of diamond.

[0015] If the amount of impurities is more than 0.3% by weight, mismatch in thermal expansion coefficient between diamond and impurities occurs in diamond grains during sintering at a high temperature, resulting in destruction of diamond particles or intragranularity. This is because abrasion resistance is likely to be reduced due to cracks or strains generated in the steel. The impurities referred to here are Al, Si, Fe, Ni, Co, Mg,
Metal elements such as Li, Mn, Ta, and Cu.
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 is not limited simply to not graphitize the diamond particles.

Although the amount of impurities in the diamond particles is preferably as small as possible, diamond particles having a purity of more than 0.01% by weight are expensive. Has an impurity of 0.01 to
It is preferred to use 0.3% by weight of diamond particles. Furthermore, after removing the amount of impurities contained in the diamond particles of each sintered body by dissolving the hard alloy as a matrix with an acid, the diamond 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.

The content of the diamond particles is 3 to 5
The reason why 0 vol% is set is that if the content of diamond particles is less than 3 vol%, the effect of improving the wear resistance is small, and 50 vol%.
If the content is more than the volume%, the strength of the diamond-containing hard member is significantly reduced. When the content of the diamond particles is 10 to 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, the mechanical strength is greatly reduced.

When the content of diamond particles is set to 30% by volume or less and the hardness of the diamond-containing hard member is set to 2500 or less, preferably 2000 or less in Vickers hardness by making the dispersion of the diamond particles uniform, Toughness and strength can be greatly increased. This is because by controlling the content and dispersibility of the diamond particles, the hardness of the diamond-containing hard member can be made substantially the same as that of the cemented carbide as the matrix. Thus, the surprising result is that even when the hardness is equal to that of the cemented carbide matrix, the wear resistance is much higher than that of a cemented carbide or a cermet alone, and can approach the wear resistance of ultrahigh-pressure sintered diamond. Obtained. The hardness of the diamond-containing hard member is 2500 or less in Vickers hardness, preferably 2000
The reason is that the Vickers hardness of the cemented carbide matrix is 2500 at the upper limit even when the amount of the binder phase is minimized,
This is because 2,000 or less is preferable in order to realize excellent toughness and strength as a cemented carbide. Here, the definition of the hardness is expressed in Vickers hardness, but the gist of the invention is to set the hardness of the diamond-containing hard member to be equal to that of a cemented carbide or cermet as a matrix,
Obviously, the hardness measurement may be performed by other methods such as Rockwell and Knoop.

In the present invention, a cemented carbide,
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, iron group metals have a catalytic action on diamond to cause a phase transition to graphite, and tend 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 diamond particles from directly contacting this liquid phase and to increase the bonding force with the matrix. In addition, diamond particles are extremely hard, and if there is a place where they are in direct contact, stress is likely to be concentrated and it is likely 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 diamond 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,
A metal selected from the group consisting of Re, Os, Rh, Ir, and Pt; an alloy of two or more elements selected from the group IVa, Va, and VIa elements of the periodic table, Al and Si; an IVa of the periodic table;
A compound selected from the group consisting of Va, group VIa elements, carbides, nitrides, oxides, silicides, borides of Al and Si, and solid solutions thereof, among which Cr, W, Mo, Nb, and Cr-M
o, Ti-Ta, Ti-Mo, Nb-V, Ti-Al-
V, TiC, TiN, Al ₂ O ₃ , SiC, WC, MoS
metals such as i ₂ , TiBN, TiAlN, TiZrN,
Alloys and compounds are preferred. These materials have a melting point or decomposition temperature of 1300 ° C. or higher. It is important that the sintering temperature be lower than the melting point of the coating layer. Then ((0.5D
+ D) /0.5D) The reason for introducing the value (K) of ³ is that, as described above, Japanese Unexamined Patent Publication No. Hei 5-239585 discloses excellent characteristics by defining the thickness of the coating layer on diamond particles. It has been proposed to obtain a diamond-containing hard member of the formula (1).

However, in order to further enhance the bonding force between the diamond particles and the WC-based cemented carbide matrix and the wear resistance of the diamond-containing hard member, the optimum coating layer volume should be adjusted according to the volume of one diamond particle. It turned out to be important to set. This is because the content of diamond particles in the hard member of the present invention is less than 50%,
This is particularly important during liquid phase sintering because diamond particles are floating like islands in the sea of a cemented carbide or cermet as a matrix.

Therefore, K is a value obtained by dividing the volume of the diamond particles including the thickness of the coating layer by the volume of the diamond particles.
Is introduced and its numerical value is optimized. The reason for limiting the numerical value is that if K is less than 1.002, the effect of the coating layer is difficult to obtain, so that the diamond particles are likely to be graphitized, and furthermore, the holding power with the matrix cannot be secured. Was set when K was 1.002. Also, if the coating layer thickness is too large, it is difficult to obtain a uniform coating layer, the characteristics are easily scattered, and the thick coating layer interferes with increasing the packing density of diamond particles and matrix raw material. It becomes difficult and causes a reduction in sinterability, that is, a reduction in compactness. As a result, the reduction in wear resistance and the phenomenon of falling off of diamond particles due to the destruction of the coating layer are accelerated. Therefore, the upper limit film thickness of 15 μm that can guarantee the strength of the coating layer itself was set. The particularly preferred upper limit film thickness is 10 μm, and particularly preferred is when the value of K is 1.01 to 1.2.

Examples of the method for forming such a coating layer include a plating method and a dipping method, in addition to a physical vapor deposition method such as a sputtering method and an ion plating method and a chemical vapor deposition method. In addition, when the diamond particles having a thick coating layer are bridged with each other, the packing density of the diamond particles or the matrix material may be reduced.
This phenomenon is likely to occur when the content of diamond particles is large, and when the content of diamond particles is too large, it becomes an obstacle in producing a hard member having excellent wear resistance. Therefore, the content of diamond particles is preferably 30% by volume or less.

The diamond-containing hard member of the present invention is preferably manufactured at a sintering temperature at which a liquid phase is formed in a cemented carbide and / or cermet. The preferred sintering temperature is 1
300-1450 ° C., particularly preferred 1300-1
400 ° C. The holding time at the sintering temperature is 1
It is preferably manufactured by conducting current pressure sintering under the conditions of 0 seconds to 10 minutes and 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 10 seconds or more and 10 minutes or less is that if the holding time is shorter than 10 seconds, the densification is insufficient, and Is too long, the transformation of diamond into graphite is likely to occur. Particularly preferred is 1 minute or more and 5 minutes or less.

The pressure is preferably 5 to 100 MPa. This is because if the applied pressure is lower than 5 MPa, the matrix of the diamond-containing hard member is less likely to be densified, and if the applied 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, the diamond particles are very dense and fall off. It is possible to obtain a diamond-containing hard member that hardly occurs. By setting the above matrix, coating film quality, coating film thickness, and sintering conditions, the material of the present invention can be made to have a density of 98% or more in theoretical density ratio, and have high strength and high wear resistance. can do.

In the coating layer, Co, Ni, W, Ti,
When at least one element selected from C and N is diffused, the bonding force between the diamond particles and the WC-based cemented carbide 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, but the components of the liquid phase, such as Co and Ni, and W, Ti, C and N dissolved therein diffuse into the coating layer. Also, C
Also diffuses from diamonds. Co, Ni, W, T
It is desirable that the diffusion of i, C, and N occurs over the entire thickness of the coating layer.

The diamond-containing hard member obtained in the present application is worked after sintering, joined to another cemented carbide, steel or the like, and is actually used. However, it contains chemically stable diamond particles, and the coating layer on the surface of the particles is removed by processing, so that brazing or the like becomes difficult. This is particularly noticeable when the diamond content is large. Then, the inventor further studied and found out a method in which the raw material of the diamond-containing hard member and the cemented carbide or steel were brought into direct contact with each other at the time of sintering, sintered, and joined at the same time as sintering.

When the diamond-containing hard member is joined to at least one of a WC-based cemented carbide and steel, a compressive residual stress is generated in the diamond-containing hard member due to the thermal expansion coefficient, and the diamond is hardened. Brazing and welding work are not required, and the field of application of the diamond-containing hard member according to the present invention can be expanded.

Also, diamond coated on the hard member, diamond-like carbon (hereinafter called Diamond)
d Like Carbon is referred to as DLC. Since at least one of the coating layers is coated with the diamond particles in the hard member as nuclei, the coating layer has extremely excellent adhesion. Since the entire hard member is coated with at least one of diamond and DLC, it exhibits excellent wear resistance and lubricity. In particular, when DLC is coated, the coating layer is smooth and excellent in lubricity, so that peeling does not easily occur, and excellent performance as a wear-resistant member can be obtained.

The excellent adhesion can be obtained particularly because the bonding force between the diamond particles in the hard member and the WC-based cemented carbide matrix is enhanced by the present invention. In addition, 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 using the diamond particles, the content of the iron group metal is 2%. ~ 50% by weight
Is excellent because it has excellent toughness, strength, hardness, sinterability, and heat crack resistance as a matrix for binding diamond particles, and the content of the iron group metal is particularly preferably 2 to 20% by weight. It is when.
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.

[0035]

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 5
4 is shown. WC powder having an average particle size of 4 μm and an average particle size of 1 μm
m Co powder was prepared, and the WC powder and the Co powder were weighed so that the Co content was 20% by weight, and the powder was pulverized and mixed using an attritor to obtain a WC-20% by weight Co powder. . Next, into diamond particles with an average particle size of 300 μm,
Chromium molybdenum (Cr-Mo) was coated by an electroless plating method. The value of K (coating layer thickness) was 1 (0 μm) in Comparative Example 1, and 1.002 (0.1 μm) in Example 1.
m), in Example 2, 1.05 (2.5 μm), Example 3
In Example 1.1 (4.8 μm) and Example 4 1.2 (9.
4 μm), 1.3 in Example 5 (14 μm), Comparative Example 2
1.5 (22 μm) in Comparative Example 3 and 1.7 (30 μm) in Comparative Example 3.
m).

As the diamond particles, diamond having an impurity content of about 0.2% by weight was used. Then, the WC-20% by weight Co powder was mixed using a ball mill so that the coated diamond particles became 25% by volume. The thus prepared powder is filled in a graphite mold having an inner diameter of 30 mm, and is filled with 0.01 Torr.
Pressure sintering was performed by applying a direct current while applying a pressure of 40 MPa in the following vacuum. Heating pattern is 1 in 10 minutes
Raise the temperature to 350 ° C, hold at that temperature for 5 minutes,
/ Min. The size of the sintered body thus obtained was a disk-shaped sintered body having a diameter of 30 mm and a thickness of 10 mm, and had a good appearance without cracks. The black scale of these sintered bodies was removed, and Examples 1 to 5 and Comparative Examples 1 to 5 were removed.
For No. 3, the specific gravity was measured by the Archimedes method, and the ratio to the theoretical density was determined. The sintered bodies of Examples 1 to 5 and Comparative Example 1 had a denseness of 95% or more with respect to the theoretical density, whereas the samples of Comparative Examples 2 and 3 had the percentages with respect to the theoretical density of 89% and 78%, respectively. %.

Next, a sintered body having a length of 3 mm, a width of 4 mm and a height of 11 mm was cut out from the sintered bodies of Examples 1 to 5 and Comparative Examples 1 to 3 and rotated about an axis at 50 m / min. 3mm long and 11m high on a cylindrical SiC grindstone with a diameter of 20mm
m was pressed at a pressure of 20 MPa for 10 minutes to measure the amount of wear.

As Comparative Example 4, the same WC to 20% by weight C as used in Examples 1 to 5 and Comparative Examples 1 to 3 were used.
o Sintering of Examples 1 to 5 and Comparative Examples 1 to 3 when the powder material (excluding diamond particles) was sintered under current-pressure sintering under the same conditions and the amount of wear of the sintered body was 100. The wear rate of the body is shown in Table 1. Examples 6 to 1 of the present application
4, 19 to 22 were evaluated in the same manner by using the wear rate of the sintered body of Comparative Example 4 assuming that the wear rate was 100.

[0039]

[Table 1]

From the results shown in Table 1, it was found that the diamond particles had a K value of 1.002 or more, a coating layer thickness of 15 μm or less, and a Cr-M
It was confirmed that Examples 1 to 5 coated with o exhibited excellent wear resistance. Among them, the samples of Examples 1 to 4 having a K value of 1.002 or more and a coating film thickness of 10 μm or less showed particularly excellent performance.

Test Example 2 In Examples 6 and 7, powder having the same composition and the same Cr-Mo coating layer thickness as those in Examples 1 and 2 was filled into a graphite mold having an inner diameter of 30 mm, and the pressure was 0.01 torr (Torr).
r) While applying a pressure of 40 MPa in the following vacuum,
N time was 10 msec, and OFF time was 2 msec. A rectangular pulse current was applied under pressure and sintering. The temperature rising pattern was raised to 1350 ° C. in 6 minutes, held at that temperature for 5 minutes, and heated at 40 ° C./min. Cooled at speed.

The wear resistance of the sintered bodies of Examples 6 and 7 was
It measured similarly to Examples 1-5 and Comparative Examples 1-4. The results are shown in Table 2. It was found that the sintered bodies of Examples 6 and 7 exhibited better wear resistance than Examples 1 and 2.

[0043]

[Table 2]

In order to investigate the reason, Examples 1, 2 and
TEM (Transmission) of 6 and 7 sintered bodies
Electron Microscope (Spectrum) for observation was prepared, and the state of the coating layer was changed to EDX (Energy Di
Spersive X-raySpectroscop
y). As a result, the Cr-
In the Mo coating layer, Co and C are diffused over the entire thickness of the coating layer, and the diffused Co and C increase the bonding force between the diamond particles and the matrix of the WC-based cemented carbide, resulting in excellent wear resistance. It was considered to have shown.

(Test Example 3) In Examples 8 to 14, TiC was added to diamond particles having an average particle diameter of 1000 μm.
To CVD (Chemical Vapor Depos)
A diamond powder (K value: 1.06) material having a thickness of 10 μm was prepared by an ition method. Using the same raw material as in Test Example 1, a WC-15% by weight Co powder was prepared.
In addition to this, the diamond particles are 0, 5, 10, 15,
20, 30, 40, 50% by volume
The mixture was mixed in a ball mill. In addition, diamond particles include
Diamond having an impurity content of 0.15% by weight in the grains was used.

The mixed powder was filled in a graphite mold having an inner diameter of 30 mm in the same manner as in Test Example 1, and was filled with 0.01 torr (T
orr) While applying a pressure of 20 MPa in a vacuum below, the ON time is 30 msec and the OFF time is 3 msec
And sintering by applying a rectangular pulse current. In the heating pattern, the temperature was raised to 1380 ° C. in 10 minutes, kept at that temperature for 2 minutes, and cooled at a rate of 50 ° C./min. The wear amount of the sintered bodies (Examples 8 to 14 and Comparative Example 5) thus produced was measured in the same manner as in Test Example 1. 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,
Each of the examples shows excellent wear resistance, but among them, Example 9 in which the content of diamond particles is 10 to 30% by volume.
Nos. To 12 have a wear ratio of 3 or less, which indicates that they exhibit particularly excellent wear resistance. In addition, the Vickers hardness of the samples of Examples 8 to 12 in which the content of diamond particles was 30% by volume or less was about 1500 kg / mm ² , which was equivalent to that of Comparative Example 5 containing no diamond 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.

[0048]

[Table 3]

Test Example 4 Next, Example 15 will be described. That is, the inner diameter is 100 m, the material of which is SCM415.
A steel disc having a thickness of 10 mm and a thickness of 10 mm was inserted into a graphite mold having a diameter of 100 mm, and WC-20 wt% Co powder was filled thereon. Then, WC-1 was prepared such that diamond powder (K value: 1.04) in which diamond particles having an average particle diameter of 300 μm were coated with TiAlN to a thickness of 2 μm was 20% by volume.
The powder mixed with 0 wt% Co powder is filled on top of the WC-20 wt% Co powder material and 0.01 torr (Torr)
r) While applying a pressure of 20 MPa in the following vacuum,
Electric current pressure sintering was performed with a rectangular pulse current having an N time of 10 msec and an OFF time of 2 msec. In addition, diamond having an impurity amount of about 0.2% by weight was used as the diamond particles.

In the heating pattern, the temperature was raised to 1350 ° C. in 20 minutes, kept at that temperature for 4 minutes, and cooled at a rate of 30 ° C./min. The disc-shaped sintered body thus obtained is
The thickness of the steel part was 10 mm, the thickness of the WC-20 wt% Co sintered body part was 5 mm, and the thickness of the diamond particle-containing cemented carbide member was 5 mm. The cross section of the test piece is mirror polished,
As a result of observation with an optical microscope, it was found that there was no crack between the layers and the layers were firmly joined.

Next, in Example 16, only the powder having the same composition as that of the layer of the diamond particle-containing superhard member of Example 15 was directly inserted into a graphite mold having an inner diameter of 100 mm, and the same sintering method as in Example 15 was used. A sintered body having a thickness of 15 mm was produced.

Next, the upper surfaces of the sintered bodies of Examples 15 and 16 (corresponding to diamond particle-containing portions in Example 15)
Was removed using a diamond grindstone, and an impact was applied 100 times with an energy of 5 joules (J) using a carbide ball having a diameter of 20 mm from a direction perpendicular to these surfaces.

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, the layer of the cemented carbide portion was bonded to steel, so that a compressive residual stress of about 400 MPa was applied to the WC of the surface of the layer of the cemented carbide member containing diamond particles due to the coefficient of thermal expansion. Introduced and toughened, and the growth of the cracks generated was stopped by the lower layer of the sintered layer of the tough cemented carbide, but as a result, it did not severely break. Without joining
Since no compressive residual stress was generated on the surface, it is considered to be severe.

Test Example 5 The test piece of Example 15 was further provided with PVD (P
physical Vapor Deposition
A test piece of Example 17 in which DLC was coated to a thickness of 5 μm by the method and a test piece of Example 18 in which diamond was coated to a thickness of 5 μm by the CVD method were produced. A WC-10 wt% Co powder produced in the same manner as in Test Example 1 was subjected to current pressure sintering under the conditions of Test Example 4 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 an Al ₂ O ₃ ball as a mating material and a rotation speed of 3 m / mi.
n and the pressure were set to 10 Newtons (N), and the wear amount and the dynamic friction coefficient were measured in the atmosphere for 60 minutes. Example 1
The wear amounts of Nos. 5 and 16 and the dynamic friction coefficient 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.

[0056]

[Table 4]

Table 4 shows the results. From the results in Table 4,
It is clear that Examples 17 and 18 coated with DLC and diamond show excellent wear resistance and very low coefficient of friction.

Test Example 6 A WC powder having an average particle size of 5 μm was mixed with a Co powder having an average particle size of 2 μm so as to be 30% by weight, and the powder was mixed and pulverized by an attritor. Next, the diamond particles having an average particle diameter of 500 μm are shown in Table 5.
Was provided with a coating layer having a K value of 1.06. That is, Example 19 is TiN, Examples 20 and 21 are W, Example 22
Coated Mo with a coating thickness of 5 μm.

[0059]

[Table 5]

The coated diamond particles were added to and mixed with the mixed powder of the WC powder and the Co powder so that the volume of the coated diamond particles was 30% by volume. This powder was sintered under the same conditions as in Test Example 2 to produce Examples 19 to 22. Comparative Example 7 made of cemented carbide produced by sintering only the mixed powder
Was also prepared. Test samples were prepared from these sintered bodies in the same manner as in Test Example 1, and a wear test was performed. Table 5 shows the results.
As shown in the graph, the wear amount ratio is 10 in Example 19 and 9 in Examples 20 to 22.

Test Example 7 A WC powder having an average particle size of 5 μm was mixed with a Co powder having an average particle size of 2 μm so as to be 5% by weight, and the powder was mixed and pulverized by an attritor.
30% by volume of the coated diamond particles used in Example 19 of Test Example 6 were mixed with this mixed powder, and the inner diameter was 100 m.
m of the 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.

[0062]

[Table 6]

That is, Example 23 is a WC-15 wt% Co cemented carbide powder, and Example 24 is a third disc, steel, on which the second, first and WC-30 wt% Co A hard alloy powder and a WC-15 wt% Co cemented carbide powder were sequentially stacked and filled, and the WC-5 wt% Co cemented carbide powder mixed with the above 30 vol% diamond particles was filled thereon. .

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

This is because the materials of Examples 23 and 24 are shown in Table 6.
It is considered that as a result of the introduction of the compressive residual stress shown in (1), the thermal stress generated between the member and the SCM415-made 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 diamond-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 10 μm,
MoS ₂ , WC with an average particle size of 5 μm, Co with an average particle size of 1 μm
Powder, diamond particles having an average particle diameter of 200 μm (powder coated with 0.3 μm of W with 0.2% by weight of impurities in the grains. K value: 1.19) were prepared, and WC-15% by weight of Co-5
% By weight (WS ₂ or MoS ₂ ) —15 vol% diamond was blended and mixed by a ball mill to prepare a powder for sintering. These powders were subjected to current pressure sintering under the conditions of Test Example 4 to obtain Examples 25 (containing WS ₂ ) and Example 26 (M
(containing oS ₂ ). Similarly, W
A powder having a composition of C-15% by weight and Co-15% by volume diamond (powder coated with W at a thickness of 0.3 μm with an impurity amount in the grain of 0.2% by weight and a K value of 1.19) was prepared and tested. The sintered body of Example 27 was produced by current pressure sintering under the conditions of 4.

Then, the samples of Examples 25, 26 and 27 were subjected to marble balls using a pin-on-disk tester, the rotational speed of the test piece was 3 m / min, and the pressure was 1
The wear amount and the dynamic friction coefficient were measured in the atmosphere at 0 Newton (N) 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.

[0069]

[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.

(Test Example 9) The WC-
20 wt% Co powder and diamond particles having an average particle diameter of 300 μm were mixed with Nb so that the value of K (coating layer thickness) was different.
Was prepared by a PVD method, and mixed with a WC-20 wt% Co powder using a ball mill in the same manner as in Test Example 1 so that the coated diamond particles became 30% by volume. The powder thus prepared was sintered under the conditions of Test Example 1, and Example 28 (K = 1.002, d = 0.1
μm), Example 29 (K = 1.01, d = 0.5 μm), Example
30 (K = 1.1, d = 4.8 μm), Example 31 (K = 1.2, d =
9.4 μm), Example 32 (K = 1.3, d = 13.7 μm)
Was produced. When the densities of these sintered bodies were measured by the Archimedes method, all the samples had a density of 95% or more in proportion to the theoretical density. further,
After sintering the sintered body using a diamond whetstone,
In the same manner as in Test Example 1, as a sand blast test and a fracture resistance test, an impact was applied from a perpendicular direction to a plane polished surface using a carbide ball having a diameter of 20 mm with an energy of 5 joules (J), and the number of impacts until the fracture occurred Was evaluated. As Comparative Example 4, the above-described WC-20% by weight Co powder material (excluding diamond particles) was subjected to current-pressure sintering under the same conditions, and the wear amount of this sintered body was set to 100, and Table 8 shows the wear ratio and the fracture resistance measurement results of the sintered bodies of Nos. 28 to 32 and Comparative Example 4.

[0072]

[Table 8]

From the results shown in Table 8, it can be seen from Examples 29 to 29 that diamond particles were coated with Nb having a K value of 1.002 to 1.1.
It was confirmed that the 31 samples exhibited particularly excellent wear resistance and strength.

[0074]

According to the present invention, the average particle diameter of a coating having a proper thickness in a cemented carbide or cermet matrix is 100 μm.
Larger than 3000μm diamond particles dispersed in a cemented carbide and / or cermet, under the condition that a liquid phase is formed under current pressure sintering, the diamond particles hardly fall off and wear resistance It is possible to provide a diamond-containing hard member having excellent resistance.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 29/08 B22F 3/10 H // C04B 35/645 C04B 35/64 N

Claims (15)

[Claims] 1. The method according to claim 1, wherein the diamond particles are made of cemented carbide or cermet, and the balance is
50% by volume and a group VIa element of the periodic table, 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, and VIa of the periodic table, aluminum (Al), and silicon (Si). Alloys, IVa, Va, VI in Periodic Table
and at least one coating layer selected from a group a element, aluminum (Al), silicon (Si) carbide, nitride, oxide, silicide, boride or a solid solution thereof. The melting point of the coating layer is 1300 ° C. or more, and the average particle diameter D of the diamond particles is 100 μm.
3,000 μm or less, and when the thickness of the coating layer is d, ((0.5D + d) /0.5D) ³
Satisfies 1.002 or more, and the thickness d of the coating layer
Is not more than 15 μm, and diamond is produced by a sintering method under metastable conditions. 2. The diamond-containing hard member according to claim 1, wherein the thickness d of the coating layer is 10 μm or less. 3. The diamond-containing hard member according to claim 1, wherein the value of K is 1.1 or less. 4. The diamond-containing hard member according to claim 1, wherein the amount of impurities contained in the diamond particles is 0.3% by weight or less. 5. The coating layer is made of cobalt (Co), nickel (Ni), tungsten (W), titanium (Ti),
2. The diamond-containing hard member according to claim 1, further comprising at least one of carbon (C) and nitrogen (N). 6. The method according to claim 1, wherein the diamond-containing member has a diamond particle content of 30% by volume or less and a Vickers hardness of 2500 or less.
The diamond-containing hard member according to the above. 7. The content of the diamond particles is 10 to 10.
The diamond-containing hard member according to claim 1, wherein the content is 30% by volume. 8. The method according to claim 8, wherein the diamond-containing hard member contains W
S _2, MoS _2, diamond-containing hard member of claim 1, wherein the lubricating material such as graphite is contained. 9. The diamond-containing hard member according to claim 1, wherein the diamond-containing hard member is bonded to at least one of tungsten carbide (WC) based cemented carbide and steel. 10. The diamond-containing hard member according to claim 1, wherein the diamond-containing hard member is coated with at least one of diamond and diamond-like carbon (DLC). 11. Except for the diamond particles, WC
And / or when the carbide, nitride or carbonitride of Ti and the binder phase metal composed of an iron group metal are 100% by weight, the content of the iron group metal is 2 to 50% by weight. The diamond-containing hard member according to claim 1, wherein 12. The diamond-containing hard member according to claim 1, wherein the content of the iron group metal is 2 to 20% by weight. 13. A metal selected from Group VIa elements of the periodic table, rhenium (Re), osmium (Os), rhodium (Rh), iridium (Ir), and platinum (Pt) as diamond particles, and IVa of the periodic table. , Va, a VIa group element,
Alloy composed of two or more elements selected from aluminum (Al) and silicon (Si), IVa and V in the periodic table
a, covering at least one selected from the group consisting of a group VIa element, aluminum (Al), silicon (Si) carbide, nitride, oxide, silicide, boride and a solid solution thereof; The average particle diameter D of the diamond particles is greater than 100 μm and not more than 3000 μm, and the thickness of the coating layer is a value of ((0.5D + d) /0.5D) ³ where d is the thickness of the coating layer. K is 1.002
3 to 50% by volume of diamond particles satisfying the above and coated so as to have a particle size of 15 μm or less, tungsten carbide (WC) powder, and a binder phase metal powder composed of an iron group metal are mixed, molded, A method for producing a diamond-containing hard member, comprising sintering at a temperature at which a metal generates a liquid phase or higher. 14. 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 10 minutes or less, and the pressure is 5
The method for producing a diamond-containing hard member according to claim 13, wherein current-pressure sintering is performed at a pressure of 100 to 100 MPa. 15. The method of claim 1, wherein the current-pressure sintering is performed for 1 to 100 msec.
2. The method according to claim 1, wherein a rectangular pulse current of c is used.
5. The method for producing a diamond-containing hard member according to 4.