JPS63105173A - Surface modifiation of whisker - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention 1 relates to a method for modifying the surface of whiskers, and more specifically, a method for easily forming a uniform metal or ceramic film on the surface of whiskers. This invention relates to a method for surface modification of whiskers that allows for.

[Conventional technology and its problems] Carbon fiber, aramid fiber, etc. have excellent properties such as being lightweight and high strength, and their use is expanding to the aerospace industry, sports building leisure industry, etc. There is.

On the other hand, whiskers are monocrystalline fibers whose mechanical properties are close to theoretical values, and are therefore attracting attention as a reinforcing agent that is even better than conventional fibers.

However, whiskers have problems with wetting and adhesion due to their integrity. Solving this problem is an important point in expanding the use of whiskers.

By the way, in general, for materials such as carbon fiber that have poor affinity with plastics and metals, methods of surface modification include surface treatment and coating with different substances, each depending on the matrix. It is used differently.

When the matrix is made of plastic, surface treatments such as vapor phase oxidation and liquid phase oxidation are generally performed.

However, for materials with perfect crystals such as whiskers, it is extremely difficult to form a moat group on the surface, and conventional surface modification methods cannot achieve sufficient surface treatment. You can't expect any results.

When the matrix is made of metal, the male surface is coated with a metal film such as aluminum or nickel or a ceramic film such as silicon carbide by chemical deposition, physical vapor deposition, or the like.

However, this method also works on continuous materials such as carbon fiber! Although it does not cause any particular problem in miscellaneous cases,
The reason for using whiskers is that they cannot be easily adopted.

This is because whiskers tend to form flocs, and their flow tends to aggregate to form large aggregates. Decomposes at the surface layer of
As a result, a thick coating is formed on the whiskers on the surface of the aggregate, but almost no coating is formed on the internal whiskers.

[Purpose of Issue IJ1] The purpose of this 5F, January is to solve the above problems, and even if various whiskers including carbon whiskers form an aggregate, the surface part and It is an object of the present invention to provide a method for modifying the surface of whiskers, which can uniformly form a thin metal or ceramic coating on the surface of any internal whisker by a simple processing operation.

[Means for Solving the Problems] The outline of IJ1 for achieving the above object is to provide a method for forming a metal or ceramic film on the surface of a whisker, in which a raw material for forming the film and the whisker are combined. A method for surface modification of whiskers, which comprises storing the whiskers in an airtight container and then heating the inside of the airtight container to a temperature higher than the decomposition temperature of the forming raw material to form a metal or ceramic coating on the surface of the whiskers. be.

The whiskers include grab eye whiskers, S
iC whisker, 5i3Na whisker, A sentence 203
whiskers, Mg O whiskers, AnN whiskers,
B4 C3 whisker, F[! 203 Whisker, Be
O whisker, M003 whisker, NiO whisker, Cr2O3 whisker/K70 (Ti 02)
b whiskers, diamond whiskers, and the like.

The graphite whiskers include those produced directly as whiskers by arc discharge or other methods, and those produced by heat-treating vapor-grown carbon fibers in an inert gas such as nitrogen or argon.

Furthermore, in this IJ], vapor-grown carbon fibers can also be included as whiskers.

In the method of the present invention, first, one or a mixture of two or more of the various whiskers described above is stored in a closed container. It is desirable that the storage state be light and uniform; for example, the whisker volume ratio [bulk specific gravity/'pF
: degree] is preferably 0.01 to 0.5, particularly 0.01 to 0.2.

Next, the raw material for forming the film is loaded into this storage container.

The loading amount of the raw material for forming the coating can be easily calculated from the total surface area of the whiskers housed in the closed container and the desired thickness of the coating.

The loading method of the raw material for forming the film must be appropriately considered depending on the type of the raw material. For example, if the raw material is a gas, there is no particular restriction, but if the raw material is a liquid or solid, there is no particular restriction. Sometimes, for example, a liquid or solid forming material is charged once in a closed container and then heated to its boiling point to form a gas, or alternatively, the forming material is gasified outside the closed container and then the forming material is (
It is desirable to adopt a method such as introducing a gaseous forming material into a closed container heated below the decomposition temperature of boiled shellfish.Furthermore, in the above method, the pressure inside the container is reduced or high vacuum is applied before loading. It is desirable to keep it.

After loading the forming 'fX material into the container, if the forming material is a gas at room temperature, it is left to stand until it is uniformly diffused between the whiskers in the container. The standing time required for diffusion cannot be absolutely determined depending on the whisker filling and soaking, but it is usually several minutes, preferably 10 minutes or more.

Further, when the forming material is liquid or solid, when the forming material is introduced into a gaseous state in advance into a heated closed container, it immediately diffuses between the whiskers in the container.

After the forming raw material is diffused in gaseous form between the whiskers in the container, the inside of this closed container is heated. This heating temperature is
The temperature is sufficient for vapor deposition of the forming raw material, and varies depending on the type of forming raw material.

There is no particular need to control the heating rate when heating to a predetermined temperature.

The time required to deposit the formation raw material on the surface of the whiskers depends on the temperature, but by increasing the temperature slightly, the deposition time can be shortened, and in some cases can be reduced to less than 5 minutes. Moreover, even if the vapor deposition time has elapsed for a predetermined time, this does not pose a particular problem.

This is because, in the method of Episode 11, the thickness of the film formed on the surface of the whiskers is the same as the thickness of the forming material loaded in the device!
' is determined by the amount, so no matter how long the heating is carried out after the forming raw material is consumed in forming the film, there will be no adverse effect on the film formation. This means that the surface modification method according to the present invention does not require strict control of the temperature increase rate, heating time, etc. when heating the inside of a closed container, and that it simplifies the operation and seals the container. The idea is to open up the flexibility of a continuous process by continuously feeding the containers into the furnace.

The coating formed by the method of this publication 171 includes A
n, Ni, Cu, Ti, Co, Ag, Fe, B, TaW
A broad term that includes metals and their alloys such as , Mo, etc., metal carbides such as Si C, Ti C, Ta C, Hf C, metal nitrides such as TiN, and carbon, etc. Examples include ceramics.

When the coating substance is a metal (including an alloy), the raw material for forming such a coating is preferably a metal compound that evaporates easily, such as a metal halogenide, or a mixture of metal compounds. Further, when the coating substance is gold-Pd5 carbide, it is preferable to use an organic metal compound, a mixture of a metal halide, a hydrocarbon, etc. as a raw material for forming the coating.

Furthermore, when a mixed gas of a metal compound and nitrogen or a nitrogen compound is used as a forming raw material, a metal nitride film can be formed.

In this way, whiskers formed with metal or ceramic coatings are suitably used as reinforcing materials in the production of &am reinforced metals (FRM).

Further, when only a carbon compound such as a hydrocarbon is used as a raw material for forming a film, a carbon film is formed on the surface of the whisker by the method of the present invention.

By further oxidizing the whiskers, which have a carbon film formed on their surface, they can be made into fiber-reinforced plastics (
It is suitably used as a reinforcing material during the production of FRP.

Furthermore, the carbon film formed on the surface of the whisker by the method of the present invention is less likely to react with molten metal such as molten aluminum than ordinary carbon dioxide, so it can be effectively used as a reinforcing material for FRM.

Next, an example of the combination of the type of film formed on the surface of the whisker and the raw material for forming the film will be shown.

That is, tungsten, SiC, etc. are added to the surface of the whisker.
, Ti C, Ta C, Hf C, Ti4N, and when coating carbon, W F b, CH35iC, respectively.
Sentence 3. Combination of TiC4 and methane, combination of TaF5 and methane, combination of HfF5 and methane, Ti
Combination of CJ14 and nitrogen.

It is better to choose carbon compounds.

Needless to say, there are many combinations of coating types and forming materials other than those described above.

Furthermore, hydrogen gas, helium gas, argon gas, or the like may be added to the closed container in addition to the forming a material for the purpose of controlling the thickness of the film, controlling the decomposition conditions, etc.

[Effect of the invention] A surface treatment method according to the present invention is as follows.

(1) It is a simple operation that involves heating a sealed container filled with whiskers and a substance that easily vaporizes. (2) In a sealed container, by heating, the substance that easily vaporizes becomes a gas and the whiskers form. Since it permeates and diffuses uniformly into the aggregate, it is possible to uniformly form a metal or ceramic film on the surface of each whisker. Since the elementary film is uniformly formed on the amorphous surface, it is more reactive than the unmodified and highly crystalline whisker surface. (4) A sealed container is filled with a predetermined amount of a liquid or solid substance that vaporizes easily, and then once vaporized and sufficiently diffused, the substance is decomposed. The surface of the whiskers can be modified to the desired degree simply by heating above the temperature. Since the film formation does not proceed any further even if the heating time is heated, there is no need to strictly control the heating time, and it has many excellent effects such as easy operation.

[Example] (Example 1) Graphite whiskers (vapor-grown carbon fibers heat-treated at 2,800°C in an argon gas atmosphere, with a diameter of 0.2 lum, v average length: 50 lum) were uniformly filled so that the bulk specific gravity was 0.05. Then, the inside of this container was evacuated (10°3 Torr), and 1 g of benzene was injected.

Next, this sealed container was heated to 100° C. in an electric furnace, and this heating was continued for 30 minutes.

Then, heat the inside of this airtight container to 1,100℃ for 30 minutes.
Hold for minutes.

As a result of observation using an electron microscope, a uniform carbon film of approximately 1 OA was formed on the surface of the graphite whisker subjected to the above surface modification treatment.

The graphite whiskers having the carbon coating were surface treated in reflux concentrated nitric acid for 5 hours.

In this way, the surface-modified and surface-treated graphite whiskers were dispersed in 100 g of "Epoxy Ebicor" 8281 manufactured by Shear Chemical Co., Ltd. to a volume ratio of 25%, and heated at 125°C and under a pressure of 10 kg/mm2. It was cured for 1 hour under these conditions to obtain a test piece with a predetermined shape.

This test piece was subjected to a tensile test according to JIS K-7113. Tensile strength is 58kg/m*2
Met.

(Comparative Example 1) The same graphite whiskers used in Example 1 were subjected to the same surface treatment as in Example 1 without surface modification, and the obtained fluidized vapor phase grown carbon fibers were It was dispersed in a matrix and cured to obtain a test piece. When the strength of this test piece was measured in the same manner as in Example 1, the tensile strength was 39 kg/+s layer 2.

(Example 2) Silicon carbide (Si
C) Whisker (diameter 0.2gm, average length 80gm
) was used in the same manner as in the previous example to obtain a test piece, and its tensile strength was measured.

As a result, the tensile strength was 52 kg/am2.

(Example 3) Fluidized gas phase growth) Experiments were carried out in the same manner as in the previous example except that 5i3Nn whiskers (diameter 0.3 m, average length 20 pm) were used instead of the elementary fibers. A piece was obtained and its tensile strength was measured.

As a result, the tensile strength was 41 kg/2 layers.

(Example 4) Methane was used for benzene conversion, and the internal pressure of the container was 1.5 atm (M!
, counter pressure) was carried out in the same manner as in Example 1, and the tensile strength of the test piece was measured.

As a result, the tensile strength was 55 kg/mm2.

(Example 5) Graphite whiskers similar to those in Example 1 were uniformly filled into a 1.000 cc heat-resistant container with A, and the bulk specific gravity was adjusted to 0.05. Vacuum the inside of this container (10-3T
5 g of methyltrichlorosilane was placed in this container, and the temperature was raised at a constant rate to 1.300° C. over 10 ν, and held at t, aoo, and “c” for 30 minutes.

Thereafter, the whisker was cooled, taken out, and its surface was measured by Auger electron spectroscopy (AES). As a result, IJI clearly showed that SiC was formed on the surface.

As a result of observation using a transmission electron microscope, the thickness of the SiC film was about 10 to 15A.

50 g of this surface-modified whisker and 180 g of aluminum alloy (8061) powder were suspended in alcohol and mixed in a mixer for 1 day. Thereafter, the solid was removed by e-filtration and dried in a vacuum dryer maintained at 100°C for 2 days. This mixture was processed using a hot isostatic press (HIP).
The molding was carried out under the conditions of 1000 atm and 1,000 atm. Furthermore, when the tensile strength was measured, it was 71 kg/Iho 2
Met.

(Comparative Example 2) The same procedure as in Example 5 was carried out except that graphite whiskers without surface modification were used. As a result, the tensile strength was 50 kg/2 carbon dioxide.

Claims (2)

[Claims] (1) In a method for forming a metal or ceramic film on the surface of whiskers, the film forming raw material and the whisker are stored in a sealed container, and then the inside of the sealed container is heated to a temperature higher than the decomposition temperature of the forming material. A method for modifying the surface of a whisker, the method comprising heating the whisker to form a metal or ceramic coating on the surface of the whisker. (2) The raw material for forming the film is a metal compound, a metal compound and a carbon compound, a metal compound and a nitrogen compound, or a carbon compound, and is a substance that easily vaporizes when heated. method for surface modification of whiskers.