JP2003160388A - Composite structural body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite structural body having compatibly high hardness and high toughness. <P>SOLUTION: This composite structural body 1 is constituted as follows: an outer circumference of a long-sized core material 4 consisting of a diamond sintered compact, in which diamond particles 2 and 2 are bonded with an iron- family metal 3, is coated with a skin member 8 of a sintered alloy in which hard particles 6 of at least one kind among a carbide, a nitride and a carbonitride of at least a metal element (M) selected from the group consisting of groups 4a, 5a and 6a in the periodic table, wherein the quantity of the iron- family metal 3 in the diamond sintered compact 4 is more than that of the iron-family metal 7 in the sintered alloy 8. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite structure in which the outer circumference of a core material made of a diamond sintered body is covered with a skin member made of a sintered alloy.

[0002]

2. Description of the Related Art Conventionally, a technique for improving the toughness in addition to the hardness and strength of a structure by covering the outer circumference of a long core material such as a fiber with another member has been studied. In Japanese Patent Laid-Open No. 11-139884, a composite ceramic calcination in which a coating layer of a second phase component is sprayed on the outer periphery of a core material (linear ceramics) made of ceramics, which is converged in one direction and compression molded and baked. A knot is described and it is disclosed that the fracture resistance of the structure is increased.

On the other hand, a diamond sintered body in which diamond particles are bonded by an iron-group metal is utilized as a cutting tool or a tool for excavation or a wear-resistant member by taking advantage of the fact that diamond has a high hardness. There is.

[0004]

However, the above-mentioned conventional diamond sintered body has a problem that the hardness is high but the toughness and the impact resistance are low, and the fracture resistance is poor when it is used as a cutting tool or a drilling tool, for example. there were.

Further, a diamond sintered body is used as a core material in the above-mentioned composite structure, and a sintered alloy mainly composed of a metal of group 4a, 5a, 6a of the periodic table such as cemented carbide (WC) is used as a skin member. Although a composite structure coated with is conceivable, the composition that achieves both high strength and high toughness of the structure has not been studied, and further, simply combining the diamond sintered body and the sintered metal, Due to the large difference in thermal expansion coefficient between the core diamond and the hard particles that are the main component of the skin member, there may be partial cracking or peeling at the interface between the core and the skin member, resulting in reduced toughness. There was a problem that led to.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a composite structure capable of achieving both high hardness and high toughness.

[0007]

Means for Solving the Problems As a result of studying the above problems, the present inventors have found that the amount of iron group metal in a diamond sintered body as a core material is more than that in a sintered alloy as a skin member. It has been found that by increasing the amount, the difference in the coefficient of thermal expansion between the two can be reduced, and a composite structure that can achieve both high hardness and high toughness can be obtained.

That is, in the composite structure of the present invention, the outer circumference of a long core made of a diamond sintered body in which diamond particles are bonded by an iron-group metal is set to the periodic table 4a, 5
From a sintered alloy in which at least one kind of hard particles of at least one kind of metal element (M) selected from the group of a and 6a metals, carbides, nitrides and carbonitrides are bound by an iron group metal The composite structure is formed by coating with the following skin member, wherein the amount of the iron group metal in the core material is larger than the amount of the iron group metal in the skin member.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The composite structure of the present invention will be described with reference to the schematic view of FIG. 1 which is an embodiment of the composite structure and FIG.

As shown in FIG. 1, the composite structure 1 has a long core (4) made of a diamond sintered body 4 in which diamond particles 2 and 2 are bonded together by an iron-group metal 3, The hard particles 6 made of one or more of carbides, nitrides and carbonitrides of at least one metal element (M) selected from the group of metals of groups 4a, 5a and 6a of the Periodic Table are iron group metals. It is covered with a skin member (8) made of a sintered alloy 8 bonded at 7.

According to the present invention, the amount of the iron group metal 3 in the core material (diamond sintered body) 4 is larger than the amount of the iron group metal 7 in the skin member (sintered alloy) 8. And
This makes it possible to reduce the difference in thermal expansion coefficient between the two and to provide a composite structure that can achieve both high hardness and high toughness. here,
The amount of iron group metal in the present invention is the total peak intensity of the iron group metal in the energy dispersive X-ray microanalysis of the cross section of the structure 1, and particularly the diamond sintered body 4
The ratio (Md / Mc) of the iron group metal 3 amount Md in the inside and the iron group metal 7 amount Mc in the sintered alloy 8 is 1.2 or more, particularly 1.5 to.
It is preferably 100.

Further, according to the present invention, the fracture toughness value of the composite structure is controlled by suppressing the amounts of the iron group metal 3 in the diamond sintered body 4 and the iron group metal 7 in the sintered alloy 8 to predetermined amounts. to improve the average particle size d ₁ of the diamond particles 2 3.5
The average particle diameter d ₁ of the diamond particles 2 is preferably 0.01 μm or less, particularly 0.01 to 2.5 μm.
The ratio (d ₁ / d ₂ ) of the hard particles 6 to the average particle diameter d ₂ is 0.0
01-1.0, especially 0.01-0.9, and even 0.05
It is desirable to be 0.8. As a result, the capillary force of the diamond sintered body 4 can be made larger than that of the sintered alloy 8 and the impregnation force of the iron group metal 3 as the binder can be made different. By sufficiently permeating the metal, the distribution of the iron group metal can be easily shifted to the diamond sintered body side. Thus if the average particle size d ₁ of Dimond particles to 3.5μm or less, the ratio of the average particle size d ₂ of an average particle diameter d ₁ and the hard particles of diamond particles (d ₁ / d ₂₎ 0. 001-
If 1.0, the fracture toughness value of the composite structure is 20 MPa.
It can be √m or more.

Even when d ₁ / d ₂ is larger than 1.0, the addition amount of the iron group metal is adjusted to a predetermined ratio that increases the diamond sintered body side, and the firing temperature is set to, for example, 1.
By setting the temperature to less than 400 ° C. or by disposing an intermediate layer that inhibits the diffusion of the iron group metal between the core material and the skin member to suppress the diffusion of the iron group metal during sintering, the iron group in the core material It is possible to have a higher metal content than that of the sintered alloy.

Further, in order to enhance the adhesion at the interface between the core material 4 and the covering member 8 and suppress local stress concentration, as shown in the distribution of the amount of iron group metal in FIG.
It is desirable that the content of the iron group metal 3 gradually decreases from the core material 4 toward the skin member 8, in other words, continuously or stepwise.

Further, for example, the average diameter of the core material 4 is 500.
The average thickness D of the core material 4 is not more than μm, particularly 2 to 200 μm, and the average thickness of the skin member 8 is not more than 500 μm, especially 0.1 to 200 μm, but in order to have a hardness of 50 GPa or more and a toughness of 18 MPa√m or more. ₁ and the average ratio of D ₂ / D ₁ between the thickness D ₂ of the skin member 8 is 0.01 to 0.5, especially 0.
It is desirable that it is from 02 to 0.2.

Further, although FIG. 1 shows the case where one core member 4, that is, the periphery of the single body is covered with the skin member 8, the present invention is not limited to this, and as shown in FIG. Further, the structure 1 of FIG. 1 may have a multifilament structure in which a plurality of, for example, four or more bundles are converged.

Next, a method for producing the composite structure of the present invention will be described with reference to the schematic view of FIG.

First, 50 wt% or more of diamond powder having an average particle diameter of 0.01 to 3.5 μm and 50 wt% or less of iron group metal powder having an average particle diameter of 10 μm or less are mixed, and paraffin wax, polystyrene, Cylinder by a molding method such as press molding, extrusion molding or cast molding by adding an organic binder such as polyethylene, ethylene-ethyl acrylate, ethylene-vinyl acetate, polybutyl methacrylate, polyethylene glycol or dibutyl phthalate and kneading. A shaped core material molding 4'is molded (step (a)).

On the other hand, 70 to 95% by weight of hard particles or components for forming hard particles having an average particle diameter of 0.02 to 10 μm and 5 to 30% by weight of iron group metal powder having an average particle diameter of 10 μm or less are mixed. , The above-mentioned binder and the like are added thereto and kneaded to produce two half-cylindrical shaped molded bodies 8 ′ for skin members by a molding method such as press molding, extrusion molding or cast molding. Formed body 8'for skin member is formed body 4'for core material
A composite molded body arranged so as to cover the outer periphery of is manufactured (step (a)).

Then, the composite molded body is co-extruded to produce a composite molded body 1'in which a core member 4'is covered with a skin member 8'and stretched to have a small diameter (step (b)). ). Further, in order to produce a structure having a multifilament structure, a plurality of the above-mentioned co-extruded elongated shaped bodies may be converged and co-extruded and molded again (step (c)).

Furthermore, the elongated elongated shaped body can be shaped into a polygon such as a cylinder, a triangular prism, a quadrangular prism, or a hexagonal prism, if desired. In addition, the long shaped bodies are aligned to form a sheet, and the long shaped bodies of the sheets are stacked so as to form a predetermined angle such as parallel, orthogonal or 45 °. You can also Further, it is also possible to mold it into an arbitrary shape by a known molding method such as a rapid protodiving method. Furthermore, it is also possible to attach or join the above-mentioned aligned sheets or a composite structure sheet obtained by slicing the sheets in the cross-sectional direction to the surface of a conventional hard alloy sintered body (lump) such as cemented carbide. is there.

After that, the composite body of the present invention can be manufactured by subjecting the molded body to binder removal processing and then firing at ultrahigh pressure. According to the present invention, in order to control the iron group metal amount of the core material 4 and the skin member 8 within a predetermined range,
As the firing conditions, a pressure of 4 GPa or more and a temperature of 1300
It is desirable that the temperature is 5 ° C. or higher and 5 minutes to 1 hour. In particular, the average particle diameter d ₁ of the diamond particles 2, 1400 ° C. if the ratio between the average particle size d ₂ of the hard particles 6 (d ₁ / d ₂₎ is 0.01 to 1.0 to 1800 ° C. If it is more than 1.0, it is preferably less than 1400 ° C.

[0023]

EXAMPLES (Example) 0 to 15% by weight of cobalt powder having an average particle size of 2 μm was added to 85 to 100% by weight of diamond particles having an average particle size shown in Table 1, and a binder and a lubricant were added thereto. After kneading by kneading, the diameter is 20 by press molding.
A mm core material was produced.

On the other hand, hard particle powders 80 to 95 shown in Table 1
5 to 1% by weight of cobalt powder having an average particle diameter of 2 μm
After adding 5% by weight, adding a binder and a lubricant thereto, and kneading the mixture, two half-cylindrical molded bodies for skin members having a wall thickness of 1 mm were prepared by press molding, and the periphery of the molded body for core material was prepared. A composite molded body covered with the above was prepared.

After forming a stretched molded body by coextruding the composite molded body, the stretched molded body 100 is obtained.
The book was converged and coextruded again to produce a multifilament type molded body. Then, the molded body was subjected to binder removal treatment, subsequently set in an ultrahigh pressure apparatus and fired at a pressure of 5 GPa under the temperature conditions shown in Table 1 to produce a composite structure.

With respect to the obtained composite structure, the toughness of the sample was measured by Vickers hardness (according to JISR1601) and IF method. Furthermore, wavelength-dispersive X-ray microanalysis analysis (EPMA) was performed on the polished cross section of the sample.
Then, the total amount of the peak strength of the iron group metal was compared with the average value of the core material and the average value of the skin member. EPM
Conditions A are acceleration voltage 15 kV, probe current 3 × 10
^-7 A, spot size 2 μm. The results are shown in Table 1.

[0027]

[Table 1]

From the results of Table 1, sample N having the same iron group metal content in the core material and the skin member and a small total Co content
o. In Nos. 1 and 2, No. 1 having a large diamond particle diameter. 1
Has a high hardness of 58 GPa but a fracture toughness of 12 MP
No. 1 having a small diamond particle diameter, which is as low as a√m. Two
Was not measurable due to peeling of the indentation. In addition, in the sample No. 3 having the same iron group metal content in the core material and the skin member, and having a large total Co content. In No. 3, although the fracture toughness was as high as 16 MPa√m, the hardness was as low as 40 GPa.

On the other hand, according to the present invention, in the sample No. 1 in which the amount of iron group metal in the core material is larger than that in the skin member. Four
12 to 12, hardness is 50 GPa or more, toughness 18M
It had excellent characteristics of Pa√m or more.

Sample No. When the dimensions of the structures 4 to 12 were measured with a microscope, the average diameter of the core material was 1
The average thickness of the skin member was 40 to 160 μm and 8 to 12 μm. The amount of Co in the sintered body is indicated by an inequality sign as a result after the movement of Co.

[0031]

As described in detail above, according to the composite structure of the present invention, the amount of the iron group metal in the diamond sintered body as the core material is made larger than that in the sintered alloy as the skin member. As a result, the difference in the coefficient of thermal expansion between the two can be reduced, and a composite structure can be obtained that has both high hardness and high toughness.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a composite structure of the present invention.

FIG. 2 is an enlarged view of a main part of the composite structure shown in FIG.

FIG. 3 is a schematic perspective view showing another example of the composite structure of the present invention.

FIG. 4 is a conceptual diagram for explaining a method for manufacturing a composite structure of the present invention.

[Explanation of symbols]

1 composite structure 2 diamond particles 3 Iron group metal 4 Core material (diamond sintered body) 6 hard particles 7 Iron group metal 8 Skin material (sintered alloy)

Claims (5)

[Claims] 1. An outer periphery of a long core made of a diamond sintered body in which diamond particles are bonded by an iron-group metal, at least one kind selected from the group of metals of groups 4a, 5a and 6a of the periodic table. A composite obtained by coating at least one hard particle selected from the group consisting of carbides, nitrides and carbonitrides of the above metal elements (M) with a skin member made of a sintered alloy in which an iron-group metal is bonded. A composite structure, wherein the amount of iron group metal in the core material is larger than the amount of iron group metal in the skin member. 2. The composite structure according to claim 1, wherein the average particle diameter d ₁ of the diamond particles is 3.5 μm or less. 3. The average particle diameter d of the diamond particles
3. The composite structure according to claim ₁ , wherein the ratio (d ₁ / d ₂ ) of _{1 to} the average particle diameter d ₂ of the hard particles is 0.001 to 1.0. 4. The content of the iron-group metal gradually decreases from the core material to the skin member.
4. The composite structure according to any one of 3 to 3. 5. The average diameter D of the core material₁And the skin member
Average thickness D₂Ratio D ₂/ D₁Is 0.01 to 0.5
The duplicate according to any one of claims 1 to 4, characterized in that
Composite structure.