JPH0681002A - Whisker coated with superfine particle, sintered compact containing the whisker and their production - Google Patents

Abstract

PURPOSE:To produce a whisker coated with the superfine particles of inorg. material, metallic material or elements and the sintered compact with the whisker as the reinforcement. CONSTITUTION:This whisker coated with superfine particles is obtained by introducing a whisker into the flow of the superfine particles of inorg. material, metallic matreial or elements and bringing the superfine particles into contact with the whisker. The coated whisker is mixed into a sintering matreial, the obtained matrix is compacted by an appropriate compacting means and sintered, and the sintered compact reinforced by the whisker is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to whiskers whose surface is coated with an inorganic material, a metal material or ultrafine particles of a single element, a sintered body containing the whiskers and a method for producing them.

The whiskers of the present invention are coated with ultrafine particles on the surface thereof, and when mixed with a sintered body, the effect is great and a sintered body having a higher strength than a conventional sintered body can be obtained.

[0003]

2. Description of the Related Art In order to improve the strength of a sintered body, especially toughness, whiskers are dispersed and mixed in a sintered body matrix to form a sintered body. The whiskers at this time are sufficiently stronger than the strength of the matrix, and the advantage is that the pullout drag force by the whiskers becomes large at the time of breakage.

The whiskers used for this purpose are used as they are without any processing or surface treatment.
In the present situation, there are many special cases in which the material is specified or a specific processing condition is set according to the material when the surface is processed, and there is no one that can be said to be appropriate in terms of cost.

[0005]

As described above, whiskers used as a reinforcing material for a sintered body are required to have high bondability with a matrix in addition to strength. Treating the surface of the whiskers with a corrosive material such as an acid or alkali, a solvent, etc. to enhance the bondability with the matrix,
Although the physical properties of the molded body are improved by coating the surface with a coating material, there is a problem that the cost is high and the physical property values do not improve up to the expected values.
Therefore, it is required to develop a low-cost material for producing a molded product having improved physical properties.

[0006]

In order to solve such a problem, the inventors of the present invention have earnestly studied, and as a result, a whisker having a surface coated with an inorganic material, a metal material or ultrafine particles of a single element is a reinforcing material for a sintered body. The present invention has been completed by finding that it is extremely suitable as The inorganic material, metallic material, or whiskers whose surface is coated with ultrafine particles of a single element used here are new materials that have not been known in this technical field.

The whiskers whose surface is coated with the inorganic material, the metallic material or the ultrafine particles of the elemental element of the present invention can be used for the flow containing the inorganic material, the metallic material or the ultrafine particles of the elemental element produced by the vapor phase method. The present inventors have also found that it is obtained by introducing whiskers to be coated therein and bringing the above-mentioned ultrafine particles and the above-mentioned whiskers to be coated into contact with each other in an active state of the ultrafine particles. It was. Therefore, a method for producing a whisker whose surface is coated with the ultrafine particles is also included in the present invention.

That is, the whiskers whose surface is coated with the inorganic material, the metallic material or the ultrafine particles of the single element according to the present invention are the CVD method or the PVD method such as the RF plasma method (Ra).
dioFrequency Plasma), whiskers to be coated are continuously or semi-continuously supplied in a flow containing an inorganic material, a metallic material or ultrafine particles of a single element generated in a gas phase by a laser method, etc. The ultrafine particles and the above-mentioned whiskers to be coated are brought into contact with each other while the ultrafine particles are in an active state to bond them, and thus a completely new material in which the ultrafine particles are firmly bonded and fixed to the whiskers to be coated is obtained. be able to.

That is, the present invention is not a uniform film on the surface of the whiskers, but ultrafine particles (0.005 μm to 1 μm).
Is strongly adhered to the surface to form a coating having projections. This not only enhances the chemical bond between the composite sintered body matrix and the whiskers, but also
The coating having projections on the surface improves the physical gripping force with the matrix to improve the physical properties of the molded product. Also, the coating is fully effective on some, but not all, of the surface.

The whiskers whose surface is coated with the ultrafine particles of the present invention include whiskers derived from inorganic materials such as glass fiber, asbestos, rock wool and silicon carbide, and those derived from metallic materials such as Fe, Ni and Co. Al,
Examples of the whiskers include Ti, Au, Ag and W.

These whiskers have an average diameter of 0.05 μm.
.About.2.0 .mu.m, average length 1 .mu.m to 200 .mu.m, but diameter and length larger than these average diameter 3 .mu.m to 20 .mu.m, average length 20 .mu.m to 1000 .mu.m.
m items are also included.

The constituents of the ultrafine particles for coating the surface of the above-mentioned whiskers are the whiskers to be coated on the surface according to the desired properties and functions of the obtained whisker having the surface coated with the ultrafine particles. Are the same or different inorganic materials, metallic materials or elemental elements, and specific examples thereof include various inorganic materials such as oxides Al ₂ O ₃ , SiO ₂ , ZrO ₂ ,
Y ₂ O ₃ , CaO, and other nitrides such as Si ₃ N ₄ , AlN,
BN and the like, carbides such as WC and SiC, and borides such as BP and BN, and other simple metals such as Si and Al,
Examples include Ni, Co, Cu, Fe, Ti, W, and various intermetallic compounds and alloys, and simple elements such as C and B that are a composite of these materials.

The ultrafine particles for coating the inorganic material, the metallic material or the whiskers of the simple substance have an average particle diameter of 1 μm or less, usually 0.1 μm or less.

The inorganic material, the metallic material or the ultrafine particles of a simple element can be generated by a known technical means, for example, by the generation of a plasma jet by arc discharge, by the arc melting, by the generation of high frequency plasma, It can be produced by physical means, such as by vaporization in gas, or by chemical means involving the reduction or oxidation of inorganic or metallic material vapors.

According to the present invention, the inorganic material, the metallic material, or the whiskers of the metallic element or the elementary element to be coated is contained in the gas flow containing the ultrafine particles of the inorganic material, the metallic material or the elementary element produced as described above. Is introduced by any means to bring the ultrafine particles into contact with the whiskers to be coated in the active state of the ultrafine particles. In this case, the ultrafine particles have just been produced by physical or chemical means, and are themselves in the nascent state, that is, in the state of having free radicals and being activated. By contact with the whiskers, they are covalently bonded to each other, and the whiskers are strongly chemically bonded to each other. In this way, the whiskers of the present invention can be obtained as whiskers in a form in which the surface of the inorganic material, the metallic material or the whiskers of a single element is strongly coated with ultrafine particles.

As a means for supplying whiskers to the air flow containing ultrafine particles, a screw feeder or a vibrating feeder used for powder supply can be used in a fixed amount, and the supplied whiskers are carried by, for example, a carrier gas. And is thrown into an air stream containing ultrafine particles.

It is more preferable to insert a dispersing device in the latter stage of the whisker supplying device so that the whiskers can be dispersed as a single body without forming a nodule or sticking together. As a means of dispersion, a flow velocity of 2 in the carrier gas
It is also possible to keep the dispersion state good by providing the supply conduit long enough to keep it at 0 m / s or more.

The contact between the inorganic material, the metallic material or the whiskers of the single element and the ultrafine particles can be repeated if necessary, and the coating amount of the ultrafine particles can be set to a desired value. Further, the above-mentioned contact can be repeated by changing the type of the ultrafine particles, and in this way, it is possible to coat the materials of a plurality of components.

In this way, whiskers of an inorganic material, a metallic material or a single element whose surface is coated with ultrafine particles of an inorganic material, a metallic material or a single element can be obtained. The amount ratio of can be varied in a wide range depending on the desired properties and functions of the desired whisker, for example, a ratio such that the ultrafine particles are 0.01% by weight to 60% by weight with respect to the coated whisker. Can be The surface coverage is 1
% To 90%, that is, whisker surfaces almost entirely covered can be used, but preferably 10 to 7
Those in the range of 0% are used.

According to the present invention, for example, ultrafine glass particles,
Ultrafine carbon particles, Al ₂ O ₃ ultrafine particles, Al ultrafine particles, Si
Inorganic material whiskers whose surface is coated with C ultrafine particles, Ti ultrafine particles, etc., such as silicon carbide, boron nitride, aluminum oxide whiskers,
Whiskers of metallic materials, such as iron, aluminum, titanium,
Whiskers of copper, gold, silver, nickel, cobalt, tungsten, etc. are obtained.

In the whiskers whose surface is coated with these ultrafine particles, when the matrix obtained by blending with the sintering raw material is molded by an appropriate molding means and baked, the adhesion between the matrices is remarkably improved by the coating of the ultrafine particles. The strength of the obtained sintered body reaches about 1.5 times as high as that of the sintered body not coated with ultrafine particles as the reinforcing material.

The sintering raw material to be blended with the whiskers is a metal or alloy powder, for example, zinc powder, magnesium powder, aluminum powder, titanium powder, iron powder, aluminum alloy powder, magnesium alloy powder, inorganic material powder, for example. Aluminum oxide, silicon dioxide, etc. are mentioned.

The strengthening effect of the whisker on the composite sintered body according to the present invention is not only improved by the conventional pulling drag force, but also the drag force is further increased because the tip of the crack is curved or deflected by the particulate projections on the surface. Since the contact surface is large, there is no stress concentration, which helps improve the strength of the composite itself.

In the present invention, the combination of the whiskers to be coated and the ultrafine particles as the coating material is not limited according to the method of the present invention, so that the coating material is appropriately selected to control the binding force between the whiskers and the matrix. (Interface control) can be performed, and strength can be set freely to some extent.

Next, the present invention will be described by way of examples.

Example 1 Production of particles in which SiC whiskers were coated with Al ₂ O ₃ Aluminum powder (Al) was supplied into a high temperature plasma obtained by high frequency heating of argon gas and oxygen, and alumina (Al ₂ O ₃ ) was supplied. A gas stream containing particulates was generated. SiC whiskers were introduced into the lower part of the gas flow to produce whiskers in which the SiC whiskers were coated with alumina fine particles.

The device used has the configuration shown in FIG.

That is, the present apparatus is a plasma torch shown by A in FIG. 1, a chamber shown by D, an ultrafine particle raw material feeding apparatus shown by E, and a raw material whisker feeding apparatus shown by B shown in FIG. And G for the ultrafine particle recovery section.

Plasma torch A has an inner diameter of 44 mm and a length of 15
A 0 mm quartz tube (1) is mainly used, a coil (2) for high frequency oscillation is attached to the outside, and a jacket tube (3) for cooling is provided on the outside. Gas outlets (4), (5) and (6) whose ejection directions are tangential, axial and radial are provided in the upper part of the plasma torch, and gas supply sources (7) and (8) are provided at these ejection ports. ), (9) to Argon 20
L / min and oxygen 10 L / min are supplied. This jetted gas is turned into plasma by the applied high frequency power source, and forms a plasma flame in the plasma torch.

An ultrafine particle raw material supply port (10) is provided in the lower part of the plasma torch, and aluminum powder is introduced into the plasma flame using a feeder E at a rate of 0.5 g / min together with a carrier gas of 6 l / min. .

Chamber D has an inner diameter of 440 mm and a length of 180
0 mm tube (16) and outer jacket tube (17) for cooling
It consists of and.

In the raw material supply section provided in the portion B, the whiskers to be coated are
The carrier gas Ar from 21 at a rate of g / min is delivered with 10 l / min and introduced into the C zone.

In this way, the SiC whiskers come into contact with the alumina ultrafine particles in the active state at the position of C, and S
The surface of the iC whiskers is covered with ultrafine particles of alumina.

Obtained whiskers (φ = 0.5, l = 1
~ 30 μm) ultrafine alumina particles (0.01-0.05)
.mu.m, mainly 0.02 .mu.m) was uniformly coated.
Observation of a strong dispersion of the whiskers in ethanol by ultrasonic waves revealed that the alumina ultrafine particles coated as described above were not separated from the SiC whiskers and a strong ultrafine particle coating was formed. did.

Example 2 SiC whiskers were coated with ultrafine carbon particles by the apparatus used in Example 1.

That is, 30 liters / minute of argon was introduced into the plasma torch to form a plasma flame, and methane gas (CH ₄ ) was supplied to the reactor 3 from the reaction gas supply port (22).
It was introduced at a rate of 1 / min to generate ultrafine carbon particles.

Then, SiC whiskers (φ0.5 μm) to be coated were introduced at a rate of 1 g / min, and the SiC whiskers were brought into contact with the ultrafine carbon particles to coat them.

The obtained SiC whiskers (φ 0.5 μ
m) was uniformly coated with ultrafine carbon particles (0.01 to 0.05 μm, mainly 0.03 μm). Observation of the coated fibers strongly dispersed in ethanol by ultrasonic waves reveals that the carbon ultrafine particles coated as described above do not separate from the SiC whiskers and a strong ultrafine particle coating is formed. found.

Example 3 A reinforced composite sintered body was prepared using the SiC whiskers whose surface was coated with the ultrafine alumina particles produced in Example 1. This composite and a reinforced composite sintered body made of the same whiskers whose surface was not coated with ultrafine particles were tested for their flexural strength. The test method is JIS R1
According to 601 three-point bending test.

The reinforced composite sintered body tested here was a composite of alumina and SiC whiskers mixed at 8: 2 (weight ratio), and a part of this alumina was coated on the surface of the SiC whiskers as ultrafine particles. The coated alumina was 20% (weight) with respect to the SiC whiskers. This composite was mixed sufficiently uniformly, shaped into φ = 40 mm and t = 7 mm, and sintered by hot pressing at 1700 ° C.-318 kgf / cm ² for 1 hour under an argon atmosphere. The results are shown in Table 1.

In Table 1, a control example is an example of a composite body which was sintered under the same conditions as above except that SiC whiskers were used as they were. The alumina used here has an average diameter of 0.4
Silicon carbide whiskers are 0.5 μm in μm, l = 1 to 3
It is 0 μm.

[0042] The relative density is an index showing the degree of sintering of the sintered body as a ratio to the theoretical density.

[Brief description of drawings]

FIG. 1 is a diagram showing a specific example of an apparatus for producing whiskers whose surface is coated with ultrafine particles of the present invention.

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[Procedure amendment]

[Submission date] May 20, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

The whiskers of the present invention are coated with ultrafine particles on the surface thereof, and when mixed with a sintered body, the effect is great and a sintered body having a strength higher than that of a conventional sintered body can be obtained.
These sintered bodies are useful as electrical insulating materials, for example, semiconductor substrates, printed wiring boards and the like, materials for high hardness and high precision machining, such as cutting tools and die bearings, and are useful as functional materials such as grain boundary capacitors and humidity sensors. It can be a material.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

According to the present invention, for example, ultrafine glass particles,
Ultrafine carbon particles, Al ₂ O ₃ ultrafine particles, Al ultrafine particles, Si
Inorganic material whiskers whose surface is coated with C ultrafine particles, Ti ultrafine particles, etc., such as silicon carbide, boron nitride, aluminum oxide whiskers,
Whiskers of metallic materials such as iron, aluminum, titanium, copper, gold, silver, nickel, cobalt, and tungsten are obtained.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

In the whiskers whose surface is coated with these ultrafine particles, when the matrix obtained by blending with the sintering raw material is molded by an appropriate molding means and baked, the adhesion with the matrix is remarkably improved by the coating of the ultrafine particles. The strength of the obtained sintered body reaches about 1.5 times as high as that of the sintered body not coated with ultrafine particles as the reinforcing material.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

In the present invention, the combination of the whiskers to be coated and the ultrafine particles as the coating material is not limited by the method of the present invention, so that the coating material is appropriately selected to control the binding force between the whiskers and the matrix ( The interface can be controlled, and the strength can be freely set to some extent.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

Example 1 Production of particles in which SiC whiskers were coated with ultrafine particles of Al ₂ O ₃ Aluminum powder (Al) was supplied into a high temperature plasma obtained by high frequency heating of argon gas and oxygen, and alumina (Al ₂ O ₃₎ to produce a gaseous stream containing ultrafine particles. SiC whiskers were introduced into the lower part of the gas flow to produce whiskers in which the SiC whiskers were coated with alumina ultrafine particles.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

That is, the apparatus is a plasma torch shown by A in FIG. 1, a chamber shown by D, an ultrafine particle raw material supply apparatus shown by E, and a raw material whisker supply apparatus shown by F which is to be coated with ultrafine particles. And G for the ultrafine particle recovery section.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

Chamber D has an inner diameter of 440 mm and a length of 800
mm tube (16) and outer jacket (17) for cooling.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

The whiskers to be coated from the raw material whisker supply port (20) are fed by the feeder F at a rate of 1 g / min with a carrier gas Ar of 10 l / min from 21 and introduced into the C zone.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

Example 2 SiC whiskers were coated with ultrafine particles of carbon by the apparatus used in Example 1 except that the gas cylinder for methane gas was used in place of the ultrafine particle raw material supply apparatus shown by E.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

That is, 30 l / min of argon was introduced into the plasma torch to form a plasma flame, and 3 l / m of methane gas (CH ₄ ) was supplied from the gas supply port (11) and the ultrafine particle raw material supply port (10). It was introduced at a rate of minutes to generate ultrafine particles of carbon.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

The obtained SiC whiskers (φ 0.5 μ
m) was uniformly coated with ultrafine carbon particles (0.01 to 0.05 μm, mainly 0.03 μm). Observation of the coated whiskers strongly dispersed in ethanol by ultrasonic waves reveals that the carbon ultrafine particles coated as described above do not separate from the SiC whiskers and a strong ultrafine particle coating is formed. found.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Miaki Hamada 3-4-8 Suehiro-cho, Kawagoe City, Saitama Prefecture

Claims (7)

[Claims] 1. A whisker whose surface is coated with an inorganic material, a metal material, or ultrafine particles of a single element. 2. The ultrafine particles have an average particle size of 0.005 μm.
The surface-coated whisker of claim 1, which is in the range of m-1 μm. 3. A whisker to be coated is introduced into a flow containing an inorganic material, a metallic material, or ultrafine particles of a simple element produced by a vapor phase method, and the whiskers to be coated are referred to as ultrafine particles. A method for producing a whisker having a surface coated with ultrafine particles of an inorganic material, a metal material or a simple element, which comprises contacting in an active state. 4. The manufacturing method according to claim 3, wherein the flow containing the inorganic material, the metal material, or the ultrafine particles of the single element is produced by the CVD method or the PVD method. 5. The manufacturing method according to claim 4, wherein the PVD method is an RF plasma method. 6. A sintered body using whiskers, the surface of which is coated with an inorganic material, a metal material, or ultrafine particles of a single element, as a reinforcing material. 7. A whisker whose surface is coated with an inorganic material, a metallic material or ultrafine particles of a single element is dispersed as a reinforcing material in a composite sintered body matrix, and the sintered body matrix in which this reinforcing material is dispersed is baked. A method for producing a sintered body, which comprises binding.