JP2003160389A - Composite structural body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly hardened composite structural body while maintaining impact resistance. <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 less 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. Knots are 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 with an iron-group metal, is utilized as a cutting tool or an excavating tool or a wear-resistant member by taking advantage of the fact that diamond has a high hardness.

[0004]

However, in the above-mentioned conventional diamond sintered body, although the hardness is high to some extent, the sinterability and impact resistance of diamond are low.
It was necessary to add a predetermined amount of metallic binder phase, and there was a limit to increase the hardness.

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 the structure may be considered, a structure for increasing the hardness of the structure has not been studied.

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 higher hardness while maintaining impact resistance.

[0007]

DISCLOSURE OF THE INVENTION As a result of studying the above-mentioned problems, the inventors of the present invention have found that a core material having a structure in which the amount of iron group metal in the diamond sintered body is smaller than that in the sintered alloy is diamond fired. By forming a composite structure in which the skin member is made of a sintered alloy by binding, it is possible to increase the diamond content ratio in the core material and to generate a compressive residual stress on the core material side. It was found that the hardness can be increased.

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 In the composite structure, the amount of iron group metal in the core material is smaller than the amount of iron group metal in the skin member.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A composite structure of the present invention will be described with reference to a schematic perspective view of FIG. 1 which is one embodiment thereof 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, An iron group metal 7 containing at least one hard particle 6 selected from the group consisting 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. It is covered with the skin member (8) of the sintered alloy 8 bonded together.

According to the present invention, the major feature is that the amount of the iron group metal 3 in the core material (diamond sintered body) 4 is smaller than the amount of the iron group metal 7 in the skin member (sintered alloy) 8. As a result, the core has a high hardness due to the characteristics of the high-content diamond, and the residual stress of compression caused by the difference in shrinkage behavior between the core and the skin member during sintering and the difference in thermal expansion coefficient. This promotes high hardness.
Further, impact resistance is maintained by the core portion reinforced by the compressive residual stress and the skin portion toughened by the iron group metal layer.

Here, the amount of iron group metal in the present invention means
It is the sum of the peak intensities of the iron group metals in the wavelength-dispersive X-ray microanalysis of the cross section of the structure 1, in particular, the amount of iron group metal 3 in the diamond sintered body 4 and the amount of iron group metal 7 in the sintered alloy 8 The ratio (Md / Mc) to the amount Mc is preferably 0.9 or less, and particularly preferably 0.25 to 0.8.

Further, according to the present invention, the amount of the iron group metal 3 in the diamond sintered body 4 and the amount of the iron group metal 7 in the sintered alloy 8 are suppressed to a predetermined amount while maintaining the impact resistance. for, 3.5 [mu] m average particle size d ₁ of the diamond particles 2 or less, it is desirable in particular 0.01～2.5Myuemu, further the average particle size d ₁ of the diamond particles 2, the hard particles 6
Ratio (d ₁ / d ₂ ) to the average particle diameter d ₂ of 1.0 to 500
It is preferably 0, particularly 1.1 to 3500, and more preferably 1.2 to 700. As a result, the capillary force of the sintered alloy 8 is made larger than that of the diamond sintered body 4, and at the time of firing, the impregnation force of the iron group metal, which is a binder partially melted at a high temperature of 1400 ° C. or higher. As a result, the distribution of the iron group metal can be shifted to the sintered alloy side. When d ₁ / d ₂ is 1.0 or less, the addition amount of the iron group metal in the diamond sintered body 4 is adjusted to be larger than that in the sintered alloy 8.
Especially by firing at a low temperature of less than 1400 ° C, M
It is possible to control d / Mc to a predetermined amount. Alternatively, T for preventing the diffusion of the iron group metal between the core material 4 and the skin member 8
It is also possible to control the content of the iron group metal by interposing a diffusion prevention layer mainly containing i or the like.

Further, in order to improve the adhesion at the interface between the core material 4 and the skin 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.
According to the present invention, the hardness of the core material 4 is 2 to 100 μm, and the average thickness of the skin member is 500 μm or less, and particularly 20 to 200 μm.
However, in order to achieve high hardness, the ratio D ₂ / D ₁ of the average diameter D ₁ of the core material 4 and the average thickness D ₂ of the skin member is 0.
It is desirable that it is 01 to 500. Furthermore, in order to impart a compressive residual stress to the core material 4 and prevent separation between the core material 4 and the core material 4, it is particularly desirable to set it to 0.3 to 100.

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 to 98% by weight of diamond powder having an average particle size of 0.01 to 3.5 μm and an average particle size of 10 μm are used.
The following iron group metal powders are mixed in an amount of 2 to 50% by weight or less and an organic binder such as paraffin wax, polystyrene, polyethylene, ethylene-ethyl acrylate, ethylene-vinyl acetate, polybutyl methacrylate, polyethylene glycol or dibutyl phthalate. Is added and kneaded, and a columnar molded body 4'for a core material is molded by a molding method such as press molding, extrusion molding or cast molding (see step (a)).

On the other hand, 70 to 95% by weight of hard particles or components for forming hard particles having an average particle size of 0.01 to 10 μm and 5 to 30% by weight of iron group metal powder having an average particle size of 10 μm or less are mixed. The above-mentioned binder and the like are added to this and kneaded to produce two half-cylindrical molded bodies 8'for skin members by a molding method such as press molding, extrusion molding 8'or cast molding. Then, a composite molded body in which the molded body for skin member 8 ′ is arranged so as to cover the outer periphery of the molded body for core 4 ′ is prepared (see 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)). reference). Further, in order to produce a structure having a multifilament structure, the co-extruded elongated shaped body 1 '
A plurality of the above may be converged and co-extruded again (see step (c)).

Further, the elongated elongated shaped body may be shaped into a cylinder, a triangular prism or a quadrangular prism as desired. It is also possible to form a sheet by arranging the sheets and stacking the long shaped articles of the sheets so as to form a predetermined angle such as parallel, orthogonal or 45 °. 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 condition, a pressure of 4 GP is applied using an ultra-high pressure device or the like.
It is preferable that the temperature is a or higher and the temperature is 1300 ° C. or higher for 5 minutes to 1 hour. In particular, the average particle diameter d ₁ of the diamond particles 2
And the ratio (d ₁ / d ₂ ) of the average particle diameter d ₂ of the hard particles 6 is 1.0 to 5000, 1400 ° C. to 1800
℃ is desirable, if less than 1.0 140
It is preferably below 0 ° C.

[0023]

EXAMPLES (Example) 2 to 20% by weight of cobalt powder having an average particle size of 2 μm was added to 80 to 98% by weight of diamond particles having an average particle size shown in Table 1, and a binder and a lubricant were added thereto. 16m in diameter by press molding after kneading
m core material molding was produced.

On the other hand, hard particle powders 80 to 90 shown in Table 1
10 to 20% by weight of cobalt powder having an average particle size of 0.5 to 2 μm is added to the weight%, and a binder and a lubricant are added to the mixture and kneaded, followed by press molding to form a half-cylindrical cylinder with a wall thickness of 2 mm. The two molded articles for the skin member of 1 were produced, and the composite molded article in which the periphery of the molded article for the core material was coated was produced.

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, and subsequently, the sample was 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.

Vickers hardness (according to JIS R1601) was measured for the obtained composite structure. Furthermore, wavelength-dispersive X-ray microanalysis analysis was performed on the polished cross section of the sample, and the total amount of peak intensities of the iron group metal was compared in magnitude with respect to each average value of the core material and the skin member. The EPMA conditions are an acceleration voltage of 1.5 kV, a probe current of 3 × 10 ⁻⁷ A, and a spot size of 2 μm. The results are shown in Table 1.

Further, when the structure of the structure was observed and the diameter of the core material and the thickness of the skin member were measured, the average of each sample was the diameter D ₁ = 130 μm of the core material and the thickness D ₂ = 2 of the skin member.
It was 0 μm. In addition, the amount of Co in the sintered body is described by an inequality sign as a result after the movement of Co.

Further, a molded body for the above composite structure is prepared,
A sheet sliced to have a thickness of 1 mm in the cross-sectional direction is bonded to a cemented carbide and sintered under ultrahigh pressure under the same conditions as above,
A cutting tool having a tool shape (SPGN120408) made of cemented carbide was brazed at a position to form a cutting edge, and a cutting tool having a cutting edge portion made of a composite structure was produced.

The obtained cutting tool was subjected to a milling cutting test under the following cutting conditions to observe the chipping state of the cutting edge after the test and to measure the wear width. The results are shown in Table 1. Work Material: High Silicon Aluminum (Al-16% Si) Cutting Speed: 1000m / min Depth of Cut: 2mm Feed: 0.1mm / Blade Cutting Time: 60min

[0030]

[Table 1]

Sample No. In Nos. 1 and 2, chipping greatly progressed during the test, and Sample No. In No. 3, the amount of wear was 52 μm, which was a very large amount of wear. On the other hand, the sample No. The tool having the composite structure of 4 to 11 does not chip and has a wear amount of 30 μm.
It was confirmed that the cutting characteristics were very excellent as m or less.

[0032]

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 smaller than that in the sintered alloy as the skin member. As a result, the content of diamond is increased, compressive residual stress is applied to the core, and a composite structure having higher hardness while maintaining impact resistance is obtained.

[Brief description of drawings]

FIG. 1 is a schematic perspective 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)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C22C 29/02 C22C 29/02 Z 29/16 29/16 P

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 structure in which one or more hard particles of the above-mentioned metal element (M) carbides, nitrides, and carbonitrides are coated with a skin member made of a sintered alloy bonded with an iron group metal. A composite structure characterized in that the amount of iron group metal in the core material is smaller 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 1.0 to 5000. 4. The content of the iron-group metal gradually increases from the core material to the skin member.
4. The composite structure according to any one of 3 to 3. 5. The ratio (D ₂ / D ₁ ) of the average diameter D _{1 of the} core material and the average thickness D ₂ of the skin member is 0.01 to 50. 7. The composite structure according to any one of 1.