JP3453839B2 - Diamond reinforced composite material and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to aircraft, engines, acoustic products, exercise equipment, etc.
TECHNICAL FIELD The present invention relates to a diamond-reinforced composite material for forming a part that requires high strength and high heat resistance, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in aircraft, engines, acoustic products, exercise equipment, etc., parts that are required to be lightweight, highly elastic, highly strong, or highly heat resistant are aluminum alloys such as duralumin, or carbon fiber reinforced composites. It has been formed from fiber reinforced composite materials such as materials. As the fiber reinforced composite material, carbon fiber reinforced resin (CFRP), carbon fiber reinforced metal in which carbon fiber is dispersed in metal, SiC fiber, glass fiber, SiC whisker, or glass whisker is dispersed in metal or plastic. Various ceramic fiber reinforced composite materials and the like are known. Fiber-reinforced composite materials have high strength and are lighter than aluminum alloys such as duralumin, so that they have been widely used in recent years.

On the other hand, in recent years, a technique has been proposed in which fibrous, acicular or whisker-like vapor-phase synthetic diamond is obtained by using a mixed gas of hydrogen and hydrocarbon as a raw material. For example, JP-A-60-200896 discloses that fibrous diamond is deposited on the surface of a substrate on which transition metal particles having a size of 1000 Å or less are adhered from a raw material gas excited and decomposed under reduced pressure. I will disclose that.
Japanese Patent Application Laid-Open No. 1-246116 discloses that a diamond film obtained by vapor phase synthesis is exposed to plasma containing oxygen, carbon dioxide, water vapor, hydrogen, halogenated hydrocarbon or carbon halide, or oxygen, carbon dioxide or water vapor. It is disclosed that needle-like, fibrous or porous diamond is obtained by heat-treating the film in an air flow containing. Japanese Unexamined Patent Publication (Kokai) No. 2-239192 discloses that a coarse diamond film obtained by vapor phase synthesis is etched to be converted into acicular diamond, and pure diamond is deposited on acicular diamond. Japanese Patent Application Laid-Open No. 1-246116 discloses a combination of needle-like, fibrous or porous diamond and other matrix materials to obtain mechanical strength such as high strength, high wear resistance, high thermal conductivity or high corrosion resistance. It suggests the possibility of producing diamond-reinforced composite materials with excellent thermal or chemical properties.

[0004]

Generally, in the production of a fiber-reinforced composite material, adhesion and bonding between the substances to be composited, that is, between the matrix and the fiber-reinforced material are major technical problems. Diamond is the material with the highest hardness and elastic modulus in a substance. Since fibrous diamond is superior in hardness and elastic modulus to fibrous reinforcing materials such as carbon, SiC or glass, fibrous diamond reinforced composite materials are better than composite materials reinforced with other fibrous materials. Is also expected to have high strength. However, vapor-phase synthetic diamond has low adhesion and bondability with other materials such as metals and plastics, and it is not easy to disperse fibrous diamond in a matrix to obtain a strong bonded state. Also, diamonds generally have poor wettability to other materials such as metals and plastics. Therefore, there is a problem that the range of the raw material of the matrix is limited in the diamond-reinforced composite material, because there are few materials having good adhesiveness and bondability to the vapor phase synthetic diamond.

It is an object of the present invention to improve the adhesion or bonding between vapor phase synthetic diamond and matrix for diamond reinforced composite materials.

A further object of the invention is to extend the range of matrix materials that can be used for diamond reinforced composite materials.

[0007]

The present invention provides a composite material reinforced with vapor phase synthetic diamond, wherein the surface of the diamond is modified to improve its bond with the matrix.

A composite material according to one aspect of the present invention comprises a matrix and a reinforcement material dispersed in the matrix and comprising vapor phase synthetic diamond, wherein the portion of the vapor phase synthetic diamond which is the interface with the matrix. The amount of hydrogen atoms present in the is 1 × 10 ¹⁵ / cm
² or less.

A composite material according to another aspect of the present invention comprises a matrix and a reinforcing material dispersed in the matrix and based on vapor-phase synthetic diamond.
The reinforcement has, at least at the interface with the matrix, a layer that bonds more strongly to the matrix than to the diamond itself, which layer provides a stronger bond between the diamond and the matrix than without it.

According to a further aspect of the invention, there is provided a method of making a diamond reinforced composite material, the method comprising:
Providing vapor-phase synthetic diamond as a reinforcement, removing hydrogen from the surface of the vapor-phase synthetic diamond, and mixing the hydrogen-depleted vapor-phase synthetic diamond with a matrix material to form a composite material And steps.

According to a further aspect of the invention, there is provided a method of making a diamond reinforced composite material, the method comprising:
A step of preparing a reinforcing material having a layer capable of bonding to a matrix material stronger than that of diamond at least on the surface and having vapor phase synthetic diamond as a main component, and mixing the reinforcing material and the matrix material to form a composite material And a step of performing.

In the present invention, the reinforcing material can be composed of at least one vapor-phase synthetic diamond selected from the group consisting of acicular diamond, diamond fiber, diamond whiskers, porous diamond and combinations thereof.

FIG. 1 is a sectional view schematically showing an example of a composite material according to the present invention. In the matrix 1, a reinforcing material 2 made of diamond is dispersed. Reinforcement 2
An intermediate layer 3 for improving the bond between the matrix and the diamond is present on the surface of the.

In one of the preferred embodiments of the present invention, hydrogen is removed from the surface of vapor phase synthetic diamond as a reinforcing material. As a result of investigating the cause of insufficient bond strength between the vapor-phase synthetic diamond and the matrix, the present inventors have found that hydrogen bonded to the surface of the diamond during the vapor-phase synthesis inhibits the bond between the matrix and the diamond. Found. For example, when a metal is used as the matrix, this hydrogen forms a brittle metal-hydrogen compound at the interface. This compound weakens the bond between diamond and metal. Therefore, when vapor phase synthetic diamond is used as a reinforcing material, it is important to remove hydrogen bonded to the surface. Also, when using a resin as the matrix, the removal of hydrogen results in a stronger bond between the diamond and the resin. According to the present invention, the amount of hydrogen atoms bonded to the diamond surface is 1 × 10 ¹⁵ /
It is cm ² or less. Practically, for example, the amount of hydrogen atoms on the diamond surface is 1.5 × 10 ¹³ /
cm ² to 1 × 10 ¹⁵ pieces / cm ² , preferably 1.5 × 1
It is 0 ¹³ pieces / cm ² to 2 × 10 ¹⁴ pieces / cm ² . Especially when a metal or an organic polymer is used as the matrix, the surface of the vapor-phase synthetic diamond having an amount of hydrogen atoms of 1 × 10 ¹⁵ / cm ² or less is bonded to the matrix with sufficient strength to give a diamond-reinforced composite material. .

In the present invention, the step of removing hydrogen from the surface of the vapor phase synthetic diamond may include heat treating the diamond at a temperature of 150 ° C. to 800 ° C. in an oxidizing atmosphere. As the oxidizing atmosphere, an atmosphere containing air or more oxygen can be used. In an oxidizing atmosphere, at a temperature of less than 150 ° C., hydrogen bonded to carbon atoms of vapor phase synthetic diamond cannot be removed sufficiently effectively. On the other hand, if the temperature exceeds 800 ° C., the diamond may be strongly eroded in the oxidizing atmosphere. In another aspect, vapor phase synthetic diamond can be heated at a temperature of 800 ° C. to 1500 ° C. under a non-oxidizing atmosphere to remove hydrogen from the surface of the diamond. As the non-oxidizing atmosphere, for example, an inert gas or vacuum can be used. Under a non-oxidizing atmosphere, temperatures below 800 ° C. are not sufficient to desorb hydrogen from carbon atoms. Meanwhile, 1500
Above the temperature of ° C, diamond may be corroded even in a non-oxidizing atmosphere. In a further aspect, the step of removing hydrogen from the surface of the vapor phase synthetic diamond comprises:
The step of exposing the diamond to a plasma containing oxygen may be included. In this case, hydrogen bonded to the surface of the diamond can be released even at room temperature.

According to another preferred aspect of the present invention, a layer composed of a material other than diamond or doped diamond is formed on at least the surface of vapor-phase synthetic diamond, and the bonding force between the diamond and the matrix is formed through the layer. Can be strengthened. This intermediate layer bonds strongly to both the diamond and the matrix. In one preferred embodiment, the intermediate layer can consist of graphite. The graphite layer can be formed, for example, by heating the surface of diamond. For example, in a non-oxidizing atmosphere, 1000 ° C to 1500
By heating the vapor phase synthetic diamond at a temperature of ° C, the surface of the diamond can be converted into a graphitic carbon layer. If the temperature is lower than 1000 ° C., the formation of graphite does not proceed so much, whereas if it exceeds 1500 ° C., the whole diamond may become graphite.

In a further preferred embodiment, the intermediate layer or the reinforcement itself may consist of vapor phase synthetic diamond doped with boron (B), nitrogen (N), or a combination thereof. B and N can be added in large amounts in the diamond without losing the mechanical properties of the diamond and improve the surface of the diamond for bonding with the matrix. B and N are suitable as impurities (dopants) in that they can be added in a considerable amount and do not deteriorate the mechanical properties of diamond. Further, B and N can be easily introduced into the diamond as impurities when the diamond is vapor-deposited. B or N-doped diamond can be deposited according to conventional techniques, such techniques being described, for example, in JP 58-135117.
And JP-A-59-137396. B, N
Or the concentration in diamond of those combinations is
It is preferably in the range of 50 to 20000 ppm. 5
Diamond doped below 0 ppm is not sufficient to improve the bondability with the matrix. On the other hand, if the concentration of impurities exceeds 20000 ppm, the strength of the doped diamond decreases. Further, in order to introduce a large amount of impurities into diamond without lowering the strength of diamond itself, it is more preferable to dope B and N into the diamond simultaneously and uniformly in a molar weight ratio of 1: 1. The process of forming diamond reinforcement coated on doped diamond is
The method may comprise forming diamond by vapor phase synthesis, and depositing a diamond layer thereon while doping with B, N or a combination thereof.

In the present invention, at least one material selected from the group consisting of metals, semimetals, ceramics, organic polymers such as resins, and combinations thereof can be used for the matrix. The matrix metal or metalloid is Al, Mg, Ti, Si, Be, Zr,
It can be selected from the group consisting of Ni, Co, Fe, Cr, and alloys thereof. The alloy preferably contains 20% or more of these metals. The matrix metal is
The surface-modified diamond is mixed, and then the mixture is subjected to plastic working such as rolling or extrusion to form a sheet-shaped or linear diamond-reinforced metal. In this case, the content of diamond in the raw material mixture is
The volume ratio is preferably 60% or less, more preferably 5 to 5
It is 0% by volume. If the raw material contains more diamond component than this, the strength of the diamond-reinforced metal will rather decrease.

On the other hand, the matrix is Al, Mg, S
It may consist of a compound selected from the group consisting of i, B, Ti, V, Zr, Nb, Mo, Hf, Ta and W carbides, nitrides, borides and oxides, and combinations thereof. Specifically, as a matrix,
Ceramics such as Si ₃ N ₄ , SiC, zirconia, alumina, and mullite can be used. Ceramics such as SiC and Si ₃ N ₄ are mixed with surface-modified diamond, then the mixture is shaped and fired to give diamond-reinforced ceramics.

When an organic polymer is used as the matrix, diamond can be combined with a thermoplastic resin or a thermosetting resin. Thermoplastic resins include addition-polymerized polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinylidene chloride, fluororesins,
Examples include polymethylmethacrylate, polycondensation type polyamides, polyesters, polycarbonates, polyphenylene oxides, polyaddition type thermoplastic polyurethanes, and ring-opening polymerization type polyacetals. A mixture of thermoplastic resin and surface modified diamond can be molded by conventional injection molding methods to provide a composite material. Thermosetting resins include urea resins, melamine resins and phenolic resins. When a thermosetting resin is used as the matrix, a composite material can be produced by mixing surface-modified diamond with a liquid matrix and heating to mix. In addition, polyimide, polyphenylene sulfide, polyether sulfone, polyether ketone, polyamide imide, epoxy resin, or the like can be used.

[0021]

By modifying the diamond surface according to the present invention, the bond between the diamond and the matrix material is significantly improved. This results not only in a composite material having excellent mechanical strength, but also in a composite material having a large area or a long length. If the surface of the vapor-phase synthetic diamond is mixed with the matrix without any modification, it is possible to obtain a composite material having low strength, and it is difficult to obtain a composite material having a large area or a long length. The composite material according to the present invention has excellent wear resistance, thermal conductivity, heat resistance, corrosion resistance, radiation resistance and high mechanical strength. The composite material of the present invention can be used in a wider range of applications than ever before and under severe conditions. For example, since the composite material of the present invention has excellent wear resistance, the sliding material can have a longer life than ever. Further, the radiation-resistant material of the present invention can be used for constructing a fuselage in the field of space aircraft. Further, the present invention extends the bondability of diamond to the matrix, thereby expanding the range of usable matrices.

The invention is described in more detail below by means of examples.

[0023]

【Example】

Example 1 A diamond as a reinforcing material was prepared as follows according to the technique described in JP-A-1-246116. In microwave plasma CVD, a diamond film having a thickness of about 100 μm was deposited on a silicon substrate. The CVD conditions are as follows.

Raw material: 3% methane-hydrogen mixed gas pressure: 40 Torr Substrate temperature: 850 ° C. The obtained diamond film was exposed to hydrogen plasma at a film temperature of 980 ° C. and a pressure of 80 Torr for about 20 minutes in a plasma etching apparatus. . The treated film was separated from the substrate by dissolving the silicon substrate with a dilute hydrofluoric acid-nitric acid mixture. As a result, the cracked diamond film was finely decomposed by the plasma treatment, and needle-like and fibrous diamonds (hereinafter referred to as diamond fibers) having an average length of about 100 μm and an average diameter of about 5 μm were obtained.

About 2 g of the obtained diamond fiber was added to the reaction chamber.
And stored in air at 500 ° C. for 1 hour. to this
As a result, hydrogen was removed from the surface of the diamond. one
However, it is difficult to directly measure the amount of hydrogen on the diamond fiber surface.
Since it was difficult, the following experiment was conducted. Same as above
Phase-deposited on a single crystal diamond substrate under similar conditions
The diamond film is housed in a reaction chamber, and at 500 ° C in air.
Hold for 1 hour. Then, the hydrogen source on the diamond film surface
ERD (Elastic Recoil Detec
Method), the amount is 9.6 × 1
0¹³Pieces / cm²Met. From this result, the diamond
The amount of hydrogen atoms on the fiber surface is also about 9.6 × 10. ¹³Pieces / cm²
Was inferred. Die with surface modified in this way
2 g of yamond fiber and 20 commercially available polyethylene pellets
g, heat to 400 ° C in the atmosphere, and injection mold
Thus, a diamond reinforced polyethylene resin was produced. Profit
The obtained diamond reinforced resin is designated as sample A. Of sample A
The elastic modulus and tensile strength were measured. The results are shown in Table 1.
Show.

Example 2 About 2 g of the diamond fiber obtained in Example 1 was placed in a reaction chamber and kept at 850 ° C. for 1 hour in a vacuum of 10 ⁻⁴ Torr. As a result, hydrogen was removed from the surface of the diamond. On the other hand, since it was difficult to directly measure the amount of hydrogen on the surface of the diamond fiber, the following experiment was conducted. Under the same conditions as above, the diamond film vapor-deposited on the single crystal diamond substrate was placed in the reaction chamber, and 1
It was kept at 850 ° C. in a vacuum of 0 ⁻⁴ Torr for 1 hour. Then, when the amount of hydrogen on the surface of the diamond film was measured by the ERD method, the amount was 7.9 × 10 ¹³ pieces / cm ² . From this result, it was estimated that the amount of hydrogen on the surface of the diamond fiber was also about 8 × 10 ¹³ pieces / cm ² . 2 g of the surface-modified diamond fiber was mixed with about 20 g of commercially available polyethylene pellets, and the mixture was mixed in the air at 40 g.
A diamond reinforced polyethylene resin was produced by heating at 0 ° C. and injection molding. The obtained diamond reinforced resin is referred to as Sample B. The elastic modulus and tensile strength of sample B were measured. The results are shown in Table 1.

Example 3 About 2 g of the diamond fiber obtained in Example 1 was placed in a reaction chamber and kept at 1200 ° C. for 1 hour in a vacuum of 10 ⁻⁴ Torr. As a result of analysis by surface-sensitized Raman spectroscopy, the ratio (Y / X) of the peak (X) of diamond carbon and the peak (Y) of graphite carbon was 0.91, confirming that graphite was formed on the surface. Was done. 2 g of the surface-modified diamond fiber was mixed with 20 g of commercially available polyethylene pellets, and the mixture was mixed in the air at 40 g.
It was heated to 0 ° C. and injection-molded to produce a diamond-reinforced polyethylene resin. The obtained composite material was used as sample C, and its elastic modulus and tensile strength were measured. The results are shown in Table 1.

Example 4 About 2 g of the diamond fiber obtained in Example 1 was placed in a reaction chamber, and a high frequency discharge of 80 W was applied at room temperature.
It was exposed to a steam atmosphere of 2 Torr for 10 minutes. This removed hydrogen from the surface of the diamond. About 2 g of the surface-modified diamond fiber and 20 g of commercially available polyethylene pellets were mixed, heated to 400 ° C. in the air, and injection-molded to prepare a diamond-reinforced polyethylene resin. The obtained composite material was designated as Sample D, and its elastic modulus and tensile strength were measured. The results are shown in Table 1.

Reference Example 1 The diamond fiber obtained in Example 1 was coated with Ti to a thickness of about 0.02 μm by a known sputtering method. 2 g of diamond fibers having a Ti layer on the surface and 20 g of commercially available polyethylene pellets were mixed and the mixture was mixed in air to
It was heated to 00 ° C. and injection-molded to produce a diamond-reinforced polyethylene resin. The obtained composite material was designated as Sample E, and its elastic modulus and tensile strength were measured. The results are shown in Table 1.

Comparative Example 1 About 2 g of the diamond fiber obtained in Example 1 was placed in the reaction chamber.
Housed and subjected to 150 W microwave discharge at room temperature
Exposed to a hydrogen atmosphere of 5 Torr for 30 minutes. on the other hand,
Under the same conditions as in Example 1, vapor phase was formed on a single crystal diamond substrate.
The synthesized diamond film was placed in a reaction chamber and at room temperature,
5 Torr hydrogen atmosphere with 150 W microwave applied
The atmosphere was exposed for 30 minutes. Hydrogen source on diamond film surface
The amount of offspring was measured by ERD to be 2.4 × 10¹⁵
Pieces / cm²Met. Therefore, the diamond fiber table
The amount of hydrogen atoms on the surface is at least 2.4 × 10.¹⁵Pieces / c
m ²Was inferred. Treated diamond fiber
Mix 2g with 20g of commercially available polyethylene pellets
Then, heat it to 400 ℃ in the atmosphere, injection mold it, and
A Mondo reinforced polyethylene resin was prepared. Obtained composite
The material is sample F, and its elastic modulus and tensile strength are measured.
did. The results are shown in Table 1. Comparative example 2 The surface of the diamond fiber obtained in Example 1 was treated.
It was directly used for forming a composite material without applying. Die
2 g of yamond fiber and 20 g of commercially available polyethylene pellets
And are mixed, heated to 400 ° C in the atmosphere, and injection molded
Thus, a diamond reinforced polyethylene resin was produced. Profit
The obtained composite material is designated as sample G, and its elastic modulus and tensile
The strength was measured. The results are shown in Table 1.

[0031]

[Table 1]

From the results shown in Table 1, it was confirmed that the diamond-reinforced polyethylene resin according to the present invention had both improved elastic modulus and tensile strength as compared with Comparative Examples.

Example 5 About 3 g of diamond fiber whose surface hydrogen was removed by synthesizing under the same conditions as in Example 1 and performing heat treatment in air
Was mixed with 30 g of Al powder in which Si was dissolved at 8% by weight, and the obtained mixture was sintered at 400 ° C. to produce a diamond-reinforced aluminum alloy. The obtained composite material was designated as H, and its elastic modulus and tensile strength were measured. The results are shown in Table 2.

Example 6 Synthesis and heat treatment in a vacuum were carried out under the same conditions as in Example 3, and about 3 g of diamond fiber having graphite formed on the surface and 30 g of Al powder in which Si was dissolved in 8% by weight. And were mixed, and the obtained mixture was sintered at 400 ° C. to prepare a diamond-reinforced aluminum alloy. The obtained composite material was designated as I, and its elastic modulus and tensile strength were measured. The results are shown in Table 2.

[0035]

[Table 2]

Reference Example 2 In microwave plasma CVD, a diamond film having a thickness of about 150 μm was deposited on a silicon substrate.
The CVD conditions are as follows.

Raw material: 3% methane-hydrogen mixed gas pressure: 40 Torr Substrate temperature: 850 ° C. The obtained diamond film was exposed to hydrogen plasma at a pressure of 80 Torr at a film temperature of 980 ° C. for about 20 minutes in a plasma etching apparatus. It was The treated film was separated from the substrate by dissolving the silicon substrate with a dilute hydrofluoric acid-nitric acid mixture. As a result, the diamond film with cracks was finely separated by plasma etching,
Needle-like and fibrous diamonds (hereinafter referred to as diamond fibers) having an average length of about 150 μm and an average diameter of about 8 μm were obtained.

Si was deposited to a thickness of about 0.03 μm on the surface of the obtained diamond fiber by a known sputtering method. Next, 3 g of diamond fiber coated with Si
Was mixed with 30 g of Al powder in which Si was dissolved at 8 wt% and the obtained mixture was sintered at 400 ° C. to produce a diamond reinforced aluminum alloy. The obtained composite material was designated as Sample J, and its elastic modulus and tensile strength were measured. The results are shown in Table 3.

Reference Example 3 The diamond fiber obtained in Reference Example 2 was placed in a reaction chamber, and a flow rate of 0.5% by volume of SiH ₄ mixed with H ₂ gas at a temperature of 1250 ° C. under a reaction chamber pressure of 60 Torr. 10
It was exposed to a gas of 00 sccm for 1 hour. Thereby, the SiC layer could be formed on the surface of the diamond fiber. It was confirmed by X-ray photoelectron spectroscopy that the surface of the diamond fiber was changed to SiC. Next, Si on the surface
3 g of diamond fiber having C was mixed with 30 g of Al powder in which Si was 8 wt% as a solid solution, and the obtained mixture was mixed with 4 g.
Sintering was performed at 00 ° C. to produce a diamond reinforced aluminum alloy. The obtained composite material was used as a sample K, and its elastic modulus and tensile strength were measured. The results are shown in Table 3.

Comparative Example 3 3 g of the intact diamond fiber obtained in Reference Example 2
And 30 g of Al powder in which Si was dissolved at 8 wt% were mixed, and the obtained mixture was sintered at 400 ° C. to produce a diamond-reinforced aluminum alloy. The obtained composite material was used as sample L, and its elastic modulus and tensile strength were measured. The results are shown in Table 3.

Example 7 A diamond film doped with B and N and having a thickness of about 120 μm was deposited on a silicon substrate in microwave plasma CVD. The CVD conditions are as follows.

Raw materials: CH ₄ gas 4% by volume, N ₂ gas 0.
5% by volume, mixed gas of 0.01% by volume of B ₂ H ₆ gas, balance H ₂ gas Pressure: 40 Torr Substrate temperature: 850 ° C. The obtained diamond film was pressed at a film temperature of 980 ° C. in a plasma etching apparatus It was exposed to hydrogen plasma at 80 Torr for about 20 minutes. The treated film was separated from the substrate by dissolving the silicon substrate with a dilute hydrofluoric acid-nitric acid mixture. As a result, the diamond film was finely decomposed, and the average length was about 120 μm and the average diameter was about 1
0 μm acicular and fibrous impurity doped diamond (hereinafter referred to as doped diamond fiber) was obtained.

The diamond fiber thus obtained contained, as impurities, about 150 ppm of B and about 220 ppm of N. Next, 3 g of doped diamond fiber and Si
Was mixed with 30 g of Al powder having a solid solution of 8% by weight, and the obtained mixture was sintered at 400 ° C. to produce a diamond-reinforced aluminum alloy. The obtained composite material was used as a sample M, and its elastic modulus and tensile strength were measured. The results are shown in Table 3.

[0044]

[Table 3]

From the results shown in Table 3, it was confirmed that the diamond-reinforced aluminum alloy according to the present invention had improved elastic modulus and tensile strength as compared with Comparative Examples.

Reference Example 4 In microwave plasma CVD, a diamond film having a thickness of about 60 μm was deposited on a silicon substrate. CVD
The conditions are as follows.

Raw material: 3% methane-hydrogen mixed gas pressure: 40 Torr Substrate temperature: 850 ° C. The obtained diamond film was exposed to hydrogen plasma at a pressure of 80 Torr at a film temperature of 980 ° C. for about 20 minutes in a plasma etching apparatus. It was The treated film was separated from the substrate by dissolving the silicon substrate with a dilute hydrofluoric acid-nitric acid mixture. As a result, the diamond film was finely separated and had an average length of about 60 μm and an average diameter of about 4 μm.
m needle-like and fibrous diamonds (hereinafter referred to as diamond fibers) were obtained.

Then, a SiC layer was formed on the surface of the obtained diamond fiber in the same manner as in Reference Example 3 . next,
5 g of diamond fiber having SiC on the surface and Si ₃
25 g of N ₄ powder and 1 g of Y ₂ O ₃ powder were mixed, and the obtained mixture was sintered at 1350 ° C. to produce diamond-reinforced silicon nitride ceramics. The obtained composite material was designated as Sample N, and its elastic modulus and bending strength were measured.
The results are shown in Table 4.

Comparative Example 4 The diamond fiber obtained in Reference Example 4 was used as it was in a composite material without surface treatment. 5 g of diamond fibers were mixed with 25 g of Si ₃ N ₄ powder and 1 g of Y ₂ O ₃ powder, and the obtained mixture was sintered at 1350 ° C. to produce diamond-reinforced silicon nitride ceramics. The obtained composite material was designated as sample O, and its elastic modulus and bending strength were measured. The results are shown in Table 4.

[0050]

[Table 4]

[0051]

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an example of a composite material according to the present invention.

[Explanation of symbols]

1 matrix 2 Reinforcement material 3 Middle class

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoji Fujimori 1-1-1 Kunyokita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works (56) Reference JP-A-2-79801 (JP, A) ) JP-A-3-9552 (JP, A) JP-A-4-2322282 (JP, A) European Patent 493351 (EP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C30B 1 / 00-35/00 C23C 16/26-16/27 D01F 9/08-9/32

Claims (8)

(57) [Claims] 1. A diamond-reinforced composite material, comprising: a matrix; and a reinforcing material dispersed in the matrix and comprising a vapor-phase synthetic diamond, wherein the vapor-phase synthetic diamond corresponds to an interface with the matrix. The amount of hydrogen atoms present in
A diamond reinforced composite material having a density of 10 ¹⁵ pieces / cm ² or less. 2. The material of claim 1, wherein the matrix comprises at least one material selected from the group consisting of metals, semi-metals, ceramics, organic polymers and combinations thereof. 3. A diamond-reinforced composite material, comprising: a matrix; and a reinforcing material dispersed in the matrix and containing vapor phase synthetic diamond as a main component, the reinforcing material being at least a boundary with the matrix. The part has a layer that is more strongly bonded to the matrix than the diamond itself, and the layer is made of graphite, and strengthens the bond between the reinforcing material and the matrix more than when the layer is not provided. Composite material. 4. A diamond-reinforced composite material, comprising: a matrix; and a reinforcing material dispersed in the matrix and containing vapor phase synthetic diamond as a main component, the reinforcing material being at least a boundary between the matrix and the matrix. The part has a layer that is more strongly bonded to the matrix than the diamond itself, and at least on its surface,
Comprising diamond doped with at least one atom selected from the group consisting of B, N and combinations thereof, said layer providing a stronger bond between said reinforcement and said matrix than it would otherwise be, Diamond reinforced composite material. Wherein said matrix is a metal, ceramic, consisting of at least one material selected from the group consisting of organic polymers and combinations thereof, according to claim 3 or
Or the material described in 4. 6. A method for producing a diamond-reinforced composite material, comprising: providing vapor-phase synthetic diamond as a reinforcing material; removing hydrogen from the surface of the vapor-phase synthetic diamond; and removing hydrogen. Mixing the vapor phase synthetic diamond and a matrix material to form a composite material.
Manufacturing method of diamond reinforced composite material. 7. A method for producing a diamond reinforced composite material, comprising a layer capable of binding to a matrix material stronger than diamond at least on the surface, said layer being composed of graphite, and mainly composed of vapor phase synthetic diamond. A method for producing a diamond-reinforced composite material, comprising: a step of preparing a reinforcing material as a component; and a step of mixing the reinforcing material and a matrix material to form a composite material. 8. A method of making a diamond reinforced composite material, wherein at least the surface is doped with at least one atom selected from the group consisting of B, N and combinations thereof,
A step of preparing a reinforcing material having a layer capable of binding to the matrix material stronger than that of diamond and having vapor phase synthetic diamond as a main component; and a step of forming a composite material by mixing the reinforcing material and the matrix material. A method for manufacturing a diamond-reinforced composite material, comprising: