JPH10310838A - Superhard composite member and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high strength composite member having a dense and uniform structure without using a superhigh pressure vessel by integratedly subjecting diamond particles coated with at least one kind of metal among eight elements such as Ir or the like, hard phases of at least one kind among four kinds of compounds such as WC or the like and bonding phase metal composed of iron family metal to SHS/HIP sintering. SOLUTION: Diamond particles are externally coated with at least one kind of metal among Ir, Os, Pt, Re, Rh, Cr, Mo and W as an external layer to prevent deterioration in diamond at the time of sintering. As for the member to be compounded with the diamond particles, at least one kind among WC, TiC, TiN and TiCN is used as hard phases, and iron family metal such as Co, Ni, Cr, Fe or the like is used as bonding phases. As for SHS/HIP sintering, since heating, pressurizing and cooling can rapidly be executed, e.g. by bringing metal silicon powder into a chain reaction with nitrogen in a pressurizing nitrogen atmosphere, sintering can be executed in a short time. Thus, the reduction of the production cost can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a super-hard composite member in which diamond particles are compounded in a sintered body such as a super-hard alloy and a method for producing the same.

[0002]

2. Description of the Related Art It is well known that a sintered body such as a WC-based cemented carbide containing diamond is produced under thermodynamically stable conditions in an ultra-high pressure vessel (5.5 GPa, 1500 ° C.). (JP-B-61-56067, JP-B-61-58432, US
P No.5158148). The technique according to this technique has a problem that the manufacturing cost is high and the shape is restricted.

[0003] Japanese Patent Application Laid-Open No. 7-34157 (prior art 1) discloses that
One of the proposals to solve this problem is to produce a diamond-containing composite member without using an ultra-high pressure vessel by sintering the solid phase under pressure and temperature conditions in which diamond is not thermodynamically stable. Is disclosed.

Further, US Pat. No. 5,096,465 (prior art 2) discloses a technique for producing a composite member holding metal-coated superhard particles (diamond or CBN) in a binder phase by an infiltration method.

[0005]

However, in the above-mentioned prior art 1, since the sintering is performed in a solid phase, the bonding between the diamond and the metal binder is not sufficient, and the diamond may fall off.

In the infiltration method of the prior art 2, the amount of dispersed diamond depends on the particle size of diamond to be added. That is, since it depends on the packing density of the diamond particles, it is difficult to produce a composite member having an arbitrary diamond particle diameter and an arbitrary diamond dispersion amount. Also,
It is difficult to produce a dense composite member by the infiltration method, and this is particularly remarkable in a large member or a deformed member. Therefore, it is manufactured without using an ultra-high pressure vessel, is sufficiently dense,
There has been a demand for a high-strength diamond-containing composite member having a uniform structure.

[0007]

SUMMARY OF THE INVENTION The composite member of the present invention meets this demand, and is composed of lr, Os, Pt, Re, Rh, and C.
a diamond particle having an outer layer coating formed of at least one metal selected from the group consisting of r, Mo, and W;
It comprises at least one hard phase selected from TiN and TiCN and a binder phase metal made of an iron group metal, and these are integrally SHS / HIP sintered. That is, a sintered body in which diamond particles are dispersed and held in a matrix such as a cemented carbide or a cermet, and is characterized by being obtained by SHS / HIP sintering.

Here, the outer layer coating of diamond particles is formed in order to prevent the deterioration of diamond. WC
In order to obtain a dense sintered body of a base cemented carbide or a TiC-based cermet, a sintering temperature higher than 1300 ° C. is preferable.
Is easy to be attacked. Thus, an outer layer coating was formed to prevent this attack. The above-mentioned outer layer coating with a metal exhibits a particularly excellent effect for preventing the deterioration of diamond. The thickness of the outer layer coating is preferably 0.1 to 50 μm. This is because if the thickness is less than 0.1 μm, the effect of coating is small, and if the thickness is more than 50 μm, the wear resistance as a hard material is reduced. Particularly preferred is 5 to 2
0 μm.

As the member to be composited with the diamond particles, it is preferable to use a WC-based cemented carbide, that is, a material having WC as a hard phase and Co or Ni as a binder phase. This is because the WC base hard alloy has a high rigidity, and is excellent in strength and toughness. Co, N
Iron group metals such as i, Cr, and Fe are preferred. It goes without saying that unavoidable impurities may be included. Inevitable impurities include, for example, Al, Ba, Ca, C
u, Fe, Mg, Mn, Ni, Si, Sr, S, O,
N, Mo, Sn, Cr and the like.

In SHS / HIP sintering, for example, a metal silicon powder and nitrogen are chemically chain-reacted in a pressurized nitrogen atmosphere, and can be rapidly heated, pressed, and cooled. The ending can be ended. Therefore, the time during which the material to be sintered is exposed to a high temperature can be shortened as compared with the case where the maximum temperature holding time is simply shortened in the conventional sintering, and the sintering can be completed without the diamond being transformed into graphite. Besides, SHS
/ HIP sintering has a great advantage in that the sintered body can be near-net-shaped because it is pressed and sintered using isotropic hydrostatic pressure. This is an important point for a super-hard member in which diamond is dispersed as in the member of the present invention, and a great merit of greatly reducing the processing cost can be obtained. Furthermore, since production can be performed in a short cycle, cost reduction can be expected by improving the operation rate of equipment.

It is preferable that the composite member has the following requirements in addition to the above requirements, alone or in combination.

(1) SHS / HIP sintering is performed under conditions where diamond is thermodynamically metastable and a liquid phase exists. By the manufacturing method using the conventional ultra-high pressure vessel,
Since diamond is sintered in a thermodynamically stable state at a temperature equal to or higher than the eutectic point of diamond and a bonding phase (such as Co), the diamond dissolves in Co in the liquid phase during sintering, It has been said that by repeating the process of re-precipitation, a direct bond (DD bond) between diamonds is generated, a skeleton is formed, and the strength of the sintered body is improved.

On the other hand, in the present invention, since diamond is sintered under metastable conditions, the dissolution of diamond in the bonding metal is suppressed as much as possible, and once the diamond is dissolved in the liquid phase, Does not reprecipitate as diamond. Therefore, direct bonding between diamonds does not occur, and the strength of the sintered body is borne by the matrix side such as a cemented carbide. Further, since sintering is completed in a short time by SHS / HIP sintering, transformation of diamond to graphite can be suppressed even when sintering is performed in the presence of a liquid phase, and a dense sintered body is formed by the formation of a liquid phase. Can be produced. Therefore, in addition to the excellent strength and toughness of the matrix itself, a sufficient sintered body strength can be obtained by improving the bonding force between the diamond and the matrix.

(2) Co is contained in the binder phase metal, and the main crystal system of Co is fcc. When sintering is performed with the appearance of a liquid phase, it is possible to obtain a super-hard composite member that is dense and has a high bonding force of diamond particles, and the main crystal system of Co can be stabilized at fcc. It should be noted that, by short-time sintering and rapid cooling, Co can be mixed with hcp crystal. Thereby, impact resistance performance is improved.

(3) ISO standards A00-08, B00-
It has a denseness that satisfies the range up to B08. By having a dense structure, it is possible to obtain a composite member having a high holding force of diamond and excellent wear resistance. Particularly preferred is A04,
It is within the range of B04. In terms of the theoretical specific gravity, it is preferable that it constitutes 98% or more of the theoretical specific gravity. Whether or not the material is dense can be evaluated by mirror-processing the cross section of this material and then observing the structure with an optical microscope.

(4) The liquid phase appearance temperature is higher than 1300 ° C. The melting point of the eutectic composition of the WC-based cemented carbide is 1320 ° C, and the sintering temperature of 1350 ° C or more required for dense sintering of this alloy causes the diamond and cemented carbide to form a liquid phase. It is expected that a composite member having a larger diamond holding power than conventional products can be expected. 13
Temperatures exceeding 00 ° C. are considerably higher than conventional methods for sintering diamond under metastable conditions, but the SHS / HIP sintering of the present invention enables rapid temperature rise and short-time sintering. Therefore, an excellent composite member in which the transformation of diamond into graphite is suppressed can be manufactured.

(5) An inner layer coating made of one or more metals selected from Co and Ni is provided between the outer layer coating and the diamond particles. C between the outer coating and the diamond particles
When coated with at least one metal selected from the group consisting of o and Ni, it can compensate for the disadvantage of a WC-based cemented carbide having a low deformability when used in applications where a strong impact is applied. In addition, since the retention of diamond particles is improved, particularly excellent performance is exhibited. The thickness of this inner coating layer is 0.1 to 100
μm is preferred. This is because if the thickness is less than 0.1 μm, the coating effect is not recognized, and if the thickness is more than 100 μm, the wear resistance as a hard material decreases. Particularly preferred is
5 to 50 μm. This inner layer coating may be provided on the hard phase particles.

(6) W, Ti, Co, Ni,
One or more elements selected from C have been diffused. If one or more elements selected from W, Ti, Co, Ni, and C are diffused in the outer layer coating, WC-based cemented carbide or TiC (N) -based cermet and metal-coated diamond particles Improves the bonding force and exhibits excellent performance.

(7) WC having a crystal grain size of more than 3 μm is contained in an arbitrary cross-sectional structure in an area ratio of 50% or more of all WC. When WC having a crystal grain size of more than 3 μm is contained in an area ratio of 50% or more of all WCs, a composite member having excellent characteristics can be obtained for applications in which a large impact force is applied, such as a mine civil engineering tool.

(8) The average particle size of the hard phase WC is 1
smaller than μm. This is because high hardness can be achieved by atomizing WC. (8) The crystal grain size is smaller than 1 μm, and WC has an arbitrary sectional structure and contains 10 to 35% by area of WC. WC having a crystal grain size of less than 1 μm is 10 to 3
When the content is 5%, the hardness of the cemented carbide is improved. Also, W
Since the C particle size is fine, the liquid phase easily penetrates into the WC particles due to the capillary force even in the short-time sintering as in the present invention, which is preferable because the sinterability is improved.

(9) The average particle size of WC is smaller than 3 μm,
And the average diameter of the diamond particles is smaller than 10 μm. In particular, the average particle size of WC is preferably from 0.1 μm to 1.5 μm. With such a configuration, it is possible to provide a composite member which is excellent for applications having relatively small impact force, such as a sliding wear-resistant material such as a bearing of a machine tool, a woodworking chip, and a drawing die. More preferably, the average particle size of WC is smaller than 1 μm, and the average particle size of diamond particles is smaller than 3 μm.

(10) Free carbon exists inside.
If free carbon is present in the cemented carbide, that is, if there is an excessive amount of carbon in the binder phase, diamond will dissolve in the liquid phase as carbon when a liquid phase is formed during sintering. It can also be expected to have the effect of being difficult to do. Further, since this free carbon has excellent lubricating properties, it functions as a composite member having self-lubricating properties when used as a sliding wear-resistant material.

(11) At least one selected from carbides of group IVa, Va and VIa elements and SiC is deposited on at least a part of the interface between the hard phase and the diamond. As raw material powder, IVa, Va, VIa group element, S
When one or more kinds selected from i are used, even when diamond is dissolved as carbon in the liquid phase of the binding metal, carbon reacts with the IVa, Va, VIa group element, or Si to form carbide, and the composite member Can contribute to the improvement of the hardness.

(12) The average diameter of the diamond particles is 10 to 10
00 μm. The average diameter of the diamond particles is 10
Fine particles of less than μm have a large surface area and are easily transformed into carbon, while large particles of more than 1000 μm have the problem of reduced strength, and those with an intermediate particle size have a good embedding effect in the matrix and fall off. There is also an advantage that it is unlikely to occur, so it is preferable to set the range within this intermediate range.

(13) The content of diamond particles is 5 to 50% by volume. If the content of diamond is less than 5% by volume, the effect of dispersing diamond cannot be expected, and 50%
If the number exceeds the limit, the number of places where the diamond is in direct contact with the diamond increases, so that the bonding force of the diamond particles to the matrix decreases and the diamond particles easily fall off.

(14) The content of the binder phase metal is 10 to 50% by volume. The amount of the binder phase in the composite member is preferably in the range of 10 to 50% by volume in order to promote dense sintering in a short time at a low temperature at which the diamond is metastable.

(15) The diamond content is varied in the thickness direction such that the diamond is increased on one surface side of the super-hard composite member and reduced on the other surface side. With such a configuration, a composite member having both hardness and toughness can be obtained. In other words, the thermal expansion coefficient of the diamond-rich side becomes smaller than the thermal expansion coefficient of the diamond-less side, so that compressive residual stress is generated in the diamond-rich side layer, and the surface layer is tough and has excellent diamond holding power. Can be produced. The manner of changing the diamond content may be stepwise or continuous.

(16) Being bonded on a substrate made of any of a WC-based cemented carbide, a TiC (N) -based cermet, and a metal material. Examples of the metal material include steel. In addition, a thin insert material can be inserted between the composite material and the metal material to suppress voids by the Kirkendall effect of the metal material. By forming a joined body of a composite material and a metal material, a member having hardness and toughness can be obtained. The bonding strength between the base and the composite member can be increased by increasing the amount of the bonding phase on the bonding surface side of the composite member. In addition, it is advantageous because a compressive residual stress can be generated on the surface due to the coefficient of thermal expansion.

(17) At least a part of the diamond particles is replaced with at least one of cubic boron nitride and wurtzite boron nitride. By SHS / HIP sintering, a dense sintered body can be manufactured in a short time within 10 minutes at low temperature, and CB
Since it is possible to prevent the deterioration of the quality of N and the like and to suppress the reaction at the interface, it is possible to manufacture a super-hard composite member having better characteristics than before. In particular, when CBN is used, it is effective to improve the bonding strength between CBN and the matrix by satisfying at least one of the following conditions. A WC-based cemented carbide is used as a matrix. The content of CBN is set to 5 to 50% by volume. Thermodynamically metastable, SHS /
HIP sintering. Use a bonded phase in which a liquid phase appears at a temperature higher than 1300 ° C.

Further, the composite material of the present invention comprises at least one hard phase selected from WC, TiC and TiN,
A super-hard composite member comprising a binder phase metal and diamond particles, which are sintered together,
Characterized by having at least one of the following. Diamond particles do not form a skeleton. There is no directly bonded portion between diamond particles. The composite member having this configuration includes not only one obtained by SHS / HIP sintering but also one manufactured by another method.

Further, each of the above-mentioned composite materials of the present invention is desirably used as a cutter bit for a shield machine. In tunnel construction and the like, a shield machine was required to excavate a shaft from a shaft without exchanging a cutter bit, and it was necessary to continue excavation to a target shaft. For this reason, such a cutter bit is required to have such a property that it does not break during cutting. As a countermeasure for this, use a hard cemented carbide or
JP-A-7-269293) and increasing the number of cutter bits (JP-A-6-74698). However, high-hardness cemented carbides tend to have reduced toughness, and fracture is inevitable. Also, increasing the number of bits leads to an increase in cost. In addition, if the number of shafts is increased, the digging continuation distance can be shortened, but the length of the machine and the cost are increased. Further, on the seabed, riverbed, etc., increasing the number of shafts would be extremely costly.

On the other hand, the super-hard composite member of the present invention has the excellent wear resistance of diamond and the excellent toughness of cemented carbide, so that long-distance excavation can be performed stably. It is possible and exhibits extremely excellent properties as a cutter bit material for shield machine. In addition, it can be manufactured without using a manufacturing process using a conventional ultrahigh-pressure generating container, and an ultra-hard composite member can be manufactured at low cost.

The above-mentioned method for producing a composite member comprises the steps of
s, Pt, Re, Rh, Cr, Mo, W, a step of coating the outer layer of diamond particles with at least one metal selected from the group consisting of: Mixing,
Charging the mixed raw material into an SHS / HIP device;
SHS / HIP sintering under a nitrogen gas pressure of 3 MPa or more.

In order to form the above-mentioned outer layer coating and inner layer coating on diamond particles among the raw material powder, a known plating method, CVD method, PVD method or the like may be used in advance.

In the step of mixing the raw material powders, it is preferable to use a mechanical alloying method. By using a mechanical alloying method (mechanical alloying), the binder phase metal becomes a raw material powder in the form of covering the hard phase particles, so that the sinterability at the time of sintering is improved and the densification is promoted.

In the step of charging the mixed raw material into the SHS / HIP apparatus, the mixed powder may be directly charged into the SHS / HIP apparatus, as well as a pre-pressed green compact, an intermediate sintered body, or a laminate of these. Including the case of charging. In order to form a joined body of the composite material and the substrate, the composite in which the mixed raw materials are arranged on the substrate may be charged into an SHS / HIP apparatus.

In the SHS / HIP method, since a large number of pieces can be sintered simultaneously in a short time without using an expensive sintering furnace, a diamond sintered body can be manufactured at low cost. SHS /
In the HIP method, inexpensive metal silicon is used as a fuel, and the metal silicon is nitrided and burned in a pressurized nitrogen atmosphere to instantaneously sinter diamond, hard phase and binder phase powder. Therefore, the sintered body can be densified without using a high-pressure reaction vessel while suppressing the transformation of the diamond into carbon. In addition, since the heat source required for sintering can be supplied from sources other than the raw material by using metal silicon as the fuel, the raw material system can be freely selected, which is advantageous as compared with SHS which obtains the heat source by the combustion reaction of the raw material. . Here, there are the following three specific means for nitriding and burning metallic silicon in a pressurized nitrogen atmosphere. (1) The mixed raw material is charged in a pressurized nitrogen atmosphere, a chemical chain reaction is caused with the metal silicon powder in the atmosphere, and sintering is performed by the reaction heat. (2) The mixed raw material is pre-pressed and encapsulated in a capsule, which is buried in a metallic silicon powder together with an igniting agent, set in a nitrogen enclosure, and the temperature is raised to increase the temperature of the metallic silicon by utilizing the natural heat generation of the igniting agent A chemical chain reaction is performed between the powder and nitrogen. (3) The mixed raw material is pre-pressed and sealed in a capsule, buried in a metal powder, set in a nitrogen sealed container, inserted with an ignition heater in the metal silicon powder, and energized from outside the nitrogen sealed container. A chemical chain reaction is performed between the metallic silicon powder and nitrogen.

In this sintering step, the nitrogen gas pressure is 3
If the pressure is lower than MPa, no combustion reaction occurs, and the densification of the composite member does not easily progress. The sintering time is preferably within 10 minutes. Particularly preferably, it is within 1 minute. At the liquid phase generation temperature of the cemented carbide, diamond is dissolved in the generated liquid phase and is likely to precipitate as carbon. However, since this reaction requires time, the liquid phase generation time is within 10 minutes,
Transformation into carbon can be suppressed as much as possible by suppressing the content within one minute.

In order to manufacture a composite member in which the content of diamond changes in the thickness direction, a plurality of types of diamond particles having different mixing ratios may be prepared in the step of mixing the raw material powders. And the mixed raw material is SHS
In the step of charging the / HIP apparatus, these mixed powders are stacked and arranged in the order of the content of diamond particles. If there are few kinds of raw materials having different mixing ratios of diamond particles, it is possible to obtain a composite material having a different composition stepwise in the thickness direction. A composite material having a continuously changing composition can be obtained. In order to join such a graded composition composite member to a substrate, it is desirable to reduce the diamond content on the joining surface side and increase the content on the surface side. In that case, the composite member in the vicinity of the joint surface may not contain any diamond particles.

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION

(Test Example 1) Commercially available diamond powder (average particle diameter 300 μm)
) Coated with 3 μm of Cr, WC powder (2 μm),
Using Co powder (2 μm), TiC powder (1.5 μm) and Ni powder (5 μm) as shown in Table 1 (volume%)
Prepare the compound powder (Sample No. 1-1 to 1-7)
Each of the compounded powders was wet-mixed with a ball mill for 5 hours and then dried.

[0041]

[Table 1]

Next, the dried powder was molded in a mold at a pressure of 200 MPa, and then vacuum-sealed in a glass capsule. This was put in a carbon crucible, and Si powder (average particle size 8
After charging 5 g of (μm), ignition pellets (Fe ₂ O ₃ —Al) were arranged above and below the combustion agent, and the whole was placed in a high-pressure vessel of a HIP device. Then, the temperature was raised to 780 ° C,
After introducing nitrogen gas to 100 MPa, the temperature was subsequently raised to 1150 ° C. and maintained for 30 minutes. At about 950 ° C, the pellet ignites
Excited the nitridation of i.

When the obtained sintered body having a diameter of 13 mm and a thickness of 5 mm was observed, no crack was observed in any of the samples. After surface grinding each sample,
When observed with an optical microscope at a magnification of 200 times, none of the samples had pores.

FIG. 1 is a photograph taken at a magnification of 200 times of the structure of Sample No. 1-1. Diamond particles shown in gray are bonded and held by white cemented carbide particles. When the presence of diamond in each sample was confirmed by X-ray diffraction, diamond particles were surely left in each sample.

Further, for comparison, the mixed powder of Sample No. 1-1 was subjected to the conventional production method (1350 ° C., 1 hour, kept in vacuum), and S
HS / HIP-sintered sintered bodies were prepared, the two comparative sintered bodies were ground and mirror-polished, and then their structures were magnified.
Photographed at 200x. FIG. 2 is a photomicrograph of the sintered body, wherein (A) is a sintered body obtained by a conventional manufacturing method, and (B) is a Cr body.
The sintered compact which carried out SHS / HIP sintering using uncoated diamond is shown. As is clear from the figure, the diamond which looks black has a deterioration which seems to be caused by graphitization at the interface with WC in the comparative example, and the diamond itself has damages such as cracks. On the other hand, in the sintered body of Sample No. 1-1 according to the method of the present invention, such deterioration and damage are not seen as shown in FIG.

(Test Example 2) Sample No. prepared in Test Example 1
Powder No. 2-1 having a composition in which WC was replaced with TiC and Co was replaced with Ni was prepared from the compounded powder of 1-1, and was sintered in the same manner as in Example 1. Then, the obtained sintered body is # 200
The surface was ground with a grinding wheel of No. 3 and finished into a disk having a diameter of 20 mm and a thickness of 5 mm.

The sintered body was subjected to sandblasting at 3 kg / cm ² for 30 minutes using SiC having an average particle size of 300 μm, and the weight reduction rate of the sintered body was determined to be 0.35%. On the other hand, when the same sand blast was applied to the sintered body of Sample No. 1-1, the weight reduction rate was 0.12%.
It was found that the wear resistance of 1-1 was far superior.
From this, it was found that WC was excellent in the hard phase, and Co was excellent in the wear resistance in the binder phase. Sample No. 1
-1 was subjected to mirror polishing, the surface was electrolytically etched, WC was removed, and the crystal system of the Co phase was identified by X-ray diffraction (Cu-Kα ray). It was confirmed that the main crystal system was fcc.

Test Example 3 Sample No. prepared in Test Example 1
The same composition as 1-7, 1600 ℃, 6GP using ultra high pressure vessel
A sintered body was prepared under the conditions of a, and was used as Sample No. 3-1. Immerse both sintered bodies of Sample Nos. 1-7 and 3-1 in aqua regia,
When o and Ni were melted, No. 1-7 became powdery, while the shape change of No. 3-1 was hardly observed.

In No. 1-7, there was no direct bonding between diamond particles and no skeleton was formed, whereas in No. 3-1, no diamond particles were formed under ultra-high pressure conditions. It is considered that direct bonding has occurred to form a skeleton.

Test Example 4 Samples were prepared in the same manner as in Test Example 3.
The same composition as No.1-6, using an ultra high pressure vessel at 1600 ° C, 6
The sintered body produced under the conditions of GPa was designated as Sample No. 4-1,
o The following tests were performed on both sintered bodies No. 1-6 and No. 4-1.

The surface of the sample was ground, and the ground surface was mirror-polished with a diamond paste, and the polished surface was observed using a SEM and a TEM.

As a result, while direct bonding between diamond particles occurred in sample No. 4-1, sample no.
It was found that this did not occur in 1-6.

(Test Example 5) Sintered bodies having the compositions shown in Table 2 were prepared in the same manner as in Example 1 except that the diamond particle size was changed to 2 µm, and Sample Nos. 5-1 to 5-6 were obtained.

[0054]

[Table 2]

Each of the samples was subjected to sandblasting in the same manner as in Test Example 2, and the weight reduction rate of the sintered body at that time was shown in Table 2 together with the bending strength. From these results, it can be seen that the erosion resistance is excellent when the content of the diamond particles is 5 to 50% by volume. It is particularly excellent when the content is 15 to 35% by volume.

(Test Example 6) Samples Nos. 6-1 to 6-5 having the same composition as Sample No. 1-5 and changing only the average diameter of diamond particles as shown in Table 3 were obtained. The sintering conditions were the same as in Test Example 2.

[0057]

[Table 3]

Table 3 shows the weight reduction ratio and bending strength of the sintered body when each sample was sandblasted in the same manner as in Test Example 2.
Shown inside. From these results, the average diameter of the diamond particles was
It can be seen that particularly excellent erosion resistance is exhibited in the sintered body of 10 to 1000 μm.

(Test Example 7) The powders having the compositions shown in Table 4 were used, and the amount of the Si fuel was changed to 10 g in the sintering conditions of Test Example 2. -4) was obtained.

[0060]

[Table 4]

Each of the obtained sintered bodies was mirror-finished, and the mirror surface was analyzed for spectrum by Raman spectroscopy. As a result, the sample
The peak intensity of the Raman line of carbon detected in No. 7-1 is
At 100%, the peak intensities of Sample Nos. 7-2 to 7-4 were all small, and the precipitation of graphite during sintering was caused by group IVa, Va, VIa elements such as Ti, Cr, or the like. It can be seen that it can be suppressed by adding Si.

Sample No. 7-2 includes TiC, sample N
It was confirmed by Auger electron spectroscopy and X-ray diffraction that SiC and Cr ₂ C ₃ were precipitated in Sample No. 7-3, and a compound thought to be ZrC was precipitated in Sample No. 7-4. Further, it was confirmed by SEM observation that the deposition position was often found on the diamond surface.

(Test Example 8) Sample No. 7-1 was prepared by further adding 5 wt% of carbon and sintering.
8-1 was produced. When both Sample No. 7-1 and Sample No. 8-1 were mirror-polished, in Sample No. 7-1, diamond was graphitized around the diamond particles, and a hole that appeared to fall off during mirror polishing was observed. Some were seen. On the other hand, in Sample No. 8-1, the periphery of the diamond particles was normal, and the presence of free carbon was confirmed by observation with a 200-fold optical microscope.

Further, both samples were subjected to a sand blast test in the same manner as in Test Example 2. As a result, the weight loss rate of Sample No. 7-1 was 0.08%, whereas that of Sample No. 8-1 was 0.04%. It was found that the sample No. 8-1 had better erosion performance.

Test Example 9 Sample Nos. 9-1 to 9-1 shown in Table 5
A composition having a composition of 9-6 was produced under the same sintering conditions as in Test Example 2. When each sample was sandblasted in the same manner as in Test Example 2, a weight reduction rate as shown in Table 5 was observed. From these results, it was determined that the amount of iron group metal forming the binder phase metal was preferably 10 to 50% by volume.

[0066]

[Table 5]

(Test Example 10) Composition (% by volume) shown in Table 6
Was pressed in layers and steel (SCM435) was pressed into a layer, vacuum-sealed in a glass capsule, and 40 g of Si was filled in the combustion agent, and SHS / HIP sintering was performed in the same manner as in Example 1. Observation of the obtained disk-shaped sintered body having a diameter of 50 mm and a thickness of 20 mm revealed that no cracks occurred between the layers and the layers were well bonded. The cross section in the thickness direction of this sintered body is mirror-polished, and the EPM
The composition analysis was performed at A, but the movement of elements between the layers was relatively small, and the diffusion of components between the layers, which was a problem in the conventional sintered body, was suppressed.

The sintered body of the present structure has high wear resistance due to the surface layer containing diamond, and high strength and high toughness due to the use of a super hard and steel layer as the inner layer.
Usually, it is a material that can achieve both contradictory characteristics. Moreover, there is a great advantage that such a material can be manufactured at low cost without using an ultrahigh-pressure container.

[0069]

[Table 6]

(Test Example 11) Sample N prepared in Test Example 5
o. A sintered body was produced in the same manner as in Test Example 5, except that the raw material powder having the same composition as in 5-2 was used and the amount of Si fuel was changed. And wrap the rake face, WC-Co
The presence or absence of pores in the phase was observed at × 200 magnification using an optical microscope. The observation result is A00-based on ISO
Classified up to B08 and described in Table 7. Table 7 also shows the bending strength of each sintered body.

[0071]

[Table 7]

From Table 7, it can be seen that the sample Nos. 11-3 and 11- in which the type A pores are less than 04 and the type B pores do not exist.
It was confirmed that the sample No. 4 was particularly dense and exhibited excellent characteristics.

(Test Example 12) Powder (rr, Os, Pt, Re, Rh) of the powder having the composition shown in Table 1 (Sample Nos. 1-1, 1-3, 1-5) was applied to the surface of a 5 μm diamond powder. ,
Using a raw material powder obtained by coating a metal such as Cr, Mo, W or the like to a thickness of about 3 μm by PVD method, a sintered body No. 12-1 to 12-1
4) was prepared. Sample No. 12-7 has two layers of coating on the diamond surface, the outer layer being composed of W and the inner layer being composed of Cr.

The sintered body thus produced was subjected to surface grinding with a # 250 grinding wheel, and the surface was ground in the same manner as in Test Example 2.
A santoblast test was performed at a pressure of kg / cm ² for 60 minutes. Table 8 shows the weight loss rate by this test.

[0075]

[Table 8]

As a result, Ir, Os, Pt, Re, R
Samples using diamond particles coated with a metal such as h, Cr, Mo, W, etc., showed lower weight loss rates and improved abrasion resistance than those without coating. did it. Moreover, it has been surprisingly found that the die strength of the sintered body using diamond having a metal coating is improved.

For comparison, samples Nos. 12-12 to 14 coated with diamond particles with Ti, Zr or V were prototyped and evaluated, and all samples were coated with Cr (N
o.12-11), the wear resistance decreased. The performance difference in wear resistance depending on the type of metal coated in this way is considered to be due to the ability to protect the diamond from attack by the liquid phase generated in the sintering process. That is, it is considered that these coating metals became a solid phase when the liquid phase was generated, thereby preventing the contact between the liquid phase and the diamond.

The presence or absence of other metal elements in the outer layer coating of Sample Nos. 12-1 to 12-14 was measured by Auger electron spectroscopy. As a result, W, Co, N
i, C, Ti (Ti is the raw material composition No. 1-3 and No. 1-5
It was found that the element was diffused. It is considered that the retention of diamond particles is improved by these diffusion elements.

(Test Example 13) WC having an average crystal grain size of 5 μm
Powder A, WC powder B having an average crystal grain size of 2 μm, WC powder C having an average crystal grain size of 0.5 μm, and Co powder having an average crystal grain size of 2 μm
Using 20 vol% and 5 vol% of diamond powder having an average crystal grain size of 50 μm, six kinds of pressing powders having different mixing ratios were produced. Sintered bodies (Sample Nos. 13-1 to 6) were obtained from these powders in the same manner as in Example 1. Then, after the structure photograph of the sintered body photographed at 5,000 times was binarized, the WC particle size distribution was measured using an image analyzer. Using these sintered bodies, a Charpy impact test and a three-point bending test with a span of 20 mm were performed. Table 9 shows the results.

[0080]

[Table 9]

As shown in the table, WC larger than 3 μm
The Charpy impact values of Sample Nos. 13 -3 to 6 in which the proportion of grains exceeded 50% were relatively higher than those of other samples, and were considered to be suitable for applications requiring impact resistance. Among them, the proportion of WC particles smaller than 1 μm is 10 to 35%.
%, The samples of Sample Nos. 13-5 and 13-6 exhibited excellent values of flexural strength, confirming that they had an excellent performance balance.

(Test Example 14) Under the same manufacturing conditions as in Test Example 1, sintered bodies (Sample Nos. 14-1 to 14-9) differing only in the particle size of the WC powder and diamond powder used were produced.
Diamond content is 30vol%, Co content is 15vol%
Fixed at%. The produced sintered body is ISO model number RNGN120400
, And the edge was subjected to a chamfering of 0.2 × to 25 °, and the granite was cut under the following conditions. The amount of wear at that time is shown in Table 10. Cutting speed: 50m / mim, feed rate:
0.2mm / rev, depth of cut: 1.0mm, no cutting oil

[0083]

[Table 10]

According to Table 10, the average particle size of WC was 3 μm or less.
In particular, the sintered body of 1 μm or less has excellent wear resistance, and the sintered body of diamond having an average particle diameter of 10 μm or less has excellent wear resistance. Therefore, it is understood that particularly preferred is a case where the average particle size of WC is 1 μm or less and the average particle size of diamond is 3 μm or less.

Test Example 15 Sample N described in Test Example 1
o. A diamond having an average particle size of 5 μm
Samples 15-1 to 15-7 in which a part or all of BN or WBN having an average particle size of 10 μm were replaced were manufactured under the same manufacturing conditions, and a sintered body having a diameter of 20 mm and a thickness of 5 mm was manufactured.

[0086]

[Table 11]

These sintered bodies were ground with a # 250 diamond grindstone, lapped, and observed with an optical microscope. As a result, cracks occurred in all samples, and C
No dropout of the BN particles was observed, and a dense sintered body could be obtained.

[0088]

As described above, according to the present invention, diamond particles having extremely high hardness and abrasion resistance can be hardened without using an ultra-high pressure vessel with a cemented carbide or cermet having high strength and toughness. A super-hard and high-strength member dispersed and held in the substrate can be obtained.

Therefore, the material of the present invention can be used for mining and civil engineering tools such as casing bits, earth auger bits and shield cutter bits, cutting tools such as woodworking, metalworking and resin processing chips, and bearings for machine tools. It can be used for wear-resistant materials such as nozzles, plastic working tools such as drawing dies, and tools for grinding.

In the method of the present invention, the SHS / HIP
By performing sintering in a short time by sintering, a dense super-hard composite member having excellent hardness and wear resistance can be obtained. Further, since the heating time and the keeping time can be shortened, further cost reduction can be expected as compared with the conventional technology.

Further, since the sintered body can be manufactured by near net shape by sintering under pressure under gas pressure isotropically, it is an excellent method for manufacturing the member of the present invention which is extremely difficult to process.

[Brief description of the drawings]

FIG. 1 is an optical micrograph showing the structure of the ultra-hard composite member of the present invention.

FIG. 2A is an optical micrograph of a sintered body obtained by a conventional manufacturing method, and FIG. 2B is an optical microscope photograph of a sintered body obtained by SHS / HIP sintering using diamond without Cr coating.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C22C 1/05 C22C 29/02 Z 29/02 C01B 31/06 Z // C01B 31/06 B22F 3/14 E

Claims (32)

[Claims] Claims: 1. Ir, Os, Pt, Re, Rh, Cr,
A diamond particle having an outer layer coating formed of at least one metal selected from Mo and W, at least one hard phase selected from WC, TiC, TiN and TiCN, and a binder phase metal comprising an iron group metal; A super-hard composite member, comprising: SHS / HIP sintered together. 2. The super-hard composite member according to claim 1, wherein the hard phase is WC and the binder phase metal is Co. 3. The super-hard composite member according to claim 1, wherein the SHS / HIP sintering is performed under the condition that the diamond is thermodynamically metastable and a liquid phase exists. 4. The ultra-hard composite member according to claim 3, wherein the binder phase metal contains Co, and the main crystal system of Co is fcc. 5. ISO standards A00-08 and B00
The super-hard composite member according to claim 3, which has a denseness satisfying a range from B08 to B08. 6. The super-hard composite member according to claim 3, wherein the liquid phase appearance temperature is higher than 1300 ° C. 7. C between the outer coating and the diamond particles
The super-hard composite member according to claim 3, further comprising an inner layer coating made of at least one metal selected from o and Ni. 8. W, Ti, Co, Ni, C in the outer layer coating
2. The super-hard composite member according to claim 1, wherein diffusion of one or more elements selected from the group consisting of: 9. The super-hard composite member according to claim 2, wherein WC having a crystal grain size of more than 3 μm is contained in an arbitrary sectional structure in an area ratio of 50% or more of all WC. 10. The super-hard composite member according to claim 2, wherein WC having a crystal grain size of less than 1 μm is contained in an arbitrary sectional structure in an area ratio of 10 to 35% of WC. 11. The super-hard composite member according to claim 2, wherein the average particle size of WC is smaller than 1 μm. 12. The WC has an average particle size of less than 3 μm,
3. The super-hard composite member according to claim 2, wherein the average diameter of the diamond particles is smaller than 10 μm. 13. The super-hard composite member according to claim 1, wherein free carbon is present therein. 14. The method according to claim 1, wherein at least one selected from the group consisting of carbides of Group IVa, Va and VIa elements and SiC is precipitated on at least a part of the interface between the hard phase and the diamond. Super hard composite member. 15. The diamond particles having an average particle size of 10 to 10
2. The super-hard composite member according to claim 1, wherein the thickness is 00 μm. 16. The super-hard composite member according to claim 1, wherein the content of the diamond particles is 5 to 50% by volume. 17. The super-hard composite member according to claim 1, wherein the content of the binder phase metal is 10 to 50% by volume. 18. The ultra-hard composite material according to claim 1, wherein the diamond content is changed in the thickness direction such that the diamond is increased on one surface side of the super-hard composite member and is reduced on the other surface side. Composite members. 19. The super-hard composite member according to claim 1, wherein the super-hard composite member is bonded to a base made of one of a WC-based cemented carbide, a TiC (N) -based cermet, and a metal material. 20. The super-hard composite member according to claim 1, wherein at least a part of the diamond particles is replaced with at least one of cubic boron nitride and wurtzite-type boron nitride. 21. Ir, Os, Pt, Re, Rh, C
diamond particles having an outer layer coating formed of at least one metal selected from r, Mo, and W; at least one hard phase selected from WC, TiC, TiN, and TiCN; and a binder phase metal, An ultra-hard composite member obtained by sintering them integrally, comprising at least one of the following. Diamond particles do not form a skeleton. There is no directly bonded portion between diamond particles. 22. The super-hard composite material according to claim 2, which is used as a cutter bit for a shield machine. 23. Ir, Os, Pt, Re, Rh, C
a step of coating the diamond particles with an outer layer of at least one metal selected from the group consisting of r, Mo, and W; a step of mixing the raw material powder containing the outer layer-coated diamond particles, the hard phase particles, and the binder phase metal; And a step of sintering the SHS / HIP under a nitrogen gas pressure of 3 MPa or more. 24. The method according to claim 23, wherein the SHS / HIP sintering includes one or more of the following steps. (1) The mixed raw material is charged in a pressurized nitrogen atmosphere, a chemical chain reaction is caused with the metal silicon powder in the atmosphere, and sintering is performed by the reaction heat. (2) The mixed raw material is pre-pressed and encapsulated in a capsule, which is buried in a metallic silicon powder together with an igniting agent, set in a nitrogen enclosure, and the temperature is raised to utilize the spontaneous heat generation of the igniting agent. A chemical chain reaction is performed between the powder and nitrogen. (3) The mixed raw material is pre-pressed and encapsulated in a capsule, buried in a metal powder, set in a nitrogen enclosure, inserted with an ignition heater in the metal silicon powder, and energized from outside the nitrogen enclosure. At an arbitrary temperature, metal silicon powder and nitrogen are subjected to a chemical chain reaction. 25. Before coating the outer layer, at least one of the diamond particles and the hard phase particles is made of Co and Ni.
24. The method according to claim 23, wherein at least one of the steps is coated. 26. As a raw material powder, IVa, Va, VI
The method for manufacturing an ultra-hard composite member according to claim 23, wherein one or more metals selected from the group a elements and Si are used. 27. The method according to claim 23, wherein the step of mixing the raw material powders uses a mechanical alloying method. 28. The method according to claim 23, wherein the sintering is performed by allowing a liquid phase to appear. 29. The method for producing an ultra-hard composite member according to claim 23, wherein the sintering time in the appearance of the liquid phase is within 1 minute. 30. In the step of mixing the raw material powders, a plurality of types having different mixing ratios of the diamond particles are prepared, and in the step of charging the mixed raw material into the SHS / HIP apparatus, the plurality of types of the mixed powders are mixed with the diamond particles. 24. The method for producing a super-hard composite member according to claim 23, wherein the components are arranged in the order of the contents, and the content of the diamond particles is changed in the thickness direction. 31. After the step of mixing the raw material powders, a step of arranging the mixed raw materials on a substrate is provided. The composite of the substrate and the mixed raw materials is charged into an SHS / HIP apparatus, 24. The method for manufacturing a super-hard composite member according to claim 23, wherein the mixed raw material is sintered by heating by combustion heat, and the sintered body is sintered and bonded to a substrate. 32. In the step of mixing raw material powders, a plurality of kinds of diamond particles having different mixing ratios are prepared, and in the step of charging the mixed raw material into an SHS / HIP apparatus, the plurality of kinds of mixed powders are mixed with diamond particles. The method for producing a super-hard composite member according to claim 31, wherein the diamond particles are arranged in the order of the content and the content of the diamond particles is changed in the thickness direction.