JP2642892B2 - Method for producing whisker-containing metal oxide sintered body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing a sintered body of a metal oxide containing whiskers as a reinforcing material. More specifically, the present invention relates to a whisker contained in a uniform dispersion state, a sintered body of a metal oxide exhibiting excellent mechanical properties, and a molded product thereof, such as a fiber,
It relates to a block, a film, and the like.

[0002]

2. Description of the Related Art Metal oxides are widely used as heat-resistant structural materials and functional materials because they have heat resistance and exhibit various electrical and magnetic properties depending on their composition. Since the fracture toughness is lower than that of metal, it is generally used as a composite containing whisker as a reinforcing material in applications requiring high mechanical strength.

[0003] By the way, a metal oxide composite containing whiskers is usually produced by a method in which fine and uniform metal oxide powder is used as a raw material, mixed with whiskers and sintered. However, in order to obtain a metal oxide powder having a strictly controlled particle size used as a raw material in this method, a complicated operation must be repeated, and a great deal of labor and time are required.
Since whiskers are damaged and unevenly dispersed, and it is difficult to obtain a sintered body having the desired mechanical strength, it is not necessarily suitable for industrial implementation.

[0004]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned drawbacks in the conventional method for producing a whisker-containing metal oxide sintered body, and has a good mechanical strength in which whiskers are uniformly dispersed and have good mechanical strength. Oxide sintered body,
The purpose of the present invention is to provide a simple manufacturing method.

[0005]

The present inventors have conducted various studies on a method for producing a metal oxide sintered body containing whiskers, and as a result, have found that a metal compound capable of producing a metal oxide by firing has The inventors have found that a metal oxide sintered body containing whiskers in a uniformly dispersed state can be obtained by uniformly dispersing the whiskers in advance and firing the whiskers, and based on this finding, led to the present invention. .

That is, according to the present invention, when manufacturing a sintered body of a metal oxide containing whiskers, the whiskers are uniformly dispersed in a metal compound capable of forming a metal oxide by firing, and the whiskers are fired. And a method for producing a whisker-containing metal oxide sintered body or a molded product thereof.

The metal compound used as a raw material in the method of the present invention and capable of producing a metal oxide upon firing includes, for example, a hydroxide of the metal or an inorganic salt such as carbonate, hydrogencarbonate, nitrate and sulfate. Organic salts such as oxalate, citrate, succinate, and malate; complex compounds such as ethylenediaminetetraacetate; oxyacid salts, multiple oxyacid salts, and alkoxylated compounds of the metal; There is. Examples of such metal compounds include magnesium hydroxide, zinc hydroxide, aluminum hydroxide, tin hydroxide, iron hydroxide, zinc carbonate, zinc nitrate, zinc oxalate, aluminum sulfate, tetraethoxy silicon, silicic acid, Potassium titanate, cobalt molybdate, sodium manganate, cobalt tungstate, lead stannate,
Bismuth stannate and the like can be mentioned.

The whiskers dispersed in these metal compounds include metal whiskers such as chromium, copper, iron, nickel and tungsten, and aluminum oxide, beryllium oxide, boron carbide, silicon carbide and silicon nitride. Ceramic whiskers can be used. The whiskers have a diameter of about 0.05 to 10 μm and a length of about 1 to 500 μm.

In the method of the present invention, it is necessary to uniformly disperse whiskers in a metal compound which forms a metal oxide upon firing. When the compound is precipitated in the form of a gel or a powder, it is preferable that the whisker be present in the solvent in advance, and the whisker be dispersed in the whisker at the same time when the metal compound is formed.

For example, in the case of preparing a metal hydroxide in which whiskers are dispersed, whiskers are dispersed in an aqueous solution containing a water-soluble salt of a predetermined metal, and this dispersion is dropped into an aqueous alkali solution to form a metal hydroxide. By depositing the hydroxide in a gel state or as a precipitate, a metal hydroxide in which whiskers are uniformly dispersed can be obtained. When preparing a metal oxalate in which whiskers are dispersed, after dispersing whiskers in an aqueous solution containing a water-soluble salt of a predetermined metal, this dispersion contains a water-soluble oxalate or oxalic acid. By dropping the solution into the aqueous solution to precipitate the metal oxalate as a precipitate, a metal oxalate in which whiskers are uniformly dispersed can be obtained.

Next, the whisker-containing metal compound thus obtained is separated from the solvent and, as it is or after being molded, is sufficiently heated at a temperature of 800 to 1300 ° C., preferably 900 to 1100 ° C. When firing,
A metal oxide sintered body containing the whiskers in a uniformly dispersed state is obtained. In the method of the present invention, a metal compound capable of forming a metal oxide upon firing may be used alone, or two or more metal compounds may be used in combination to form a composite oxide.

In the method of the present invention, if sintering is carried out without forming, the whisker-containing metal oxide sintered body is obtained as an agglomerate, which can be appropriately crushed and used.
In the case of molding prior to firing, a molded article of any shape such as fibrous, block, plate, or tubular can be obtained as desired. Furthermore, a laminate or a composite can also be produced by applying a precipitate or a gel precipitated in the above-mentioned solution in a thin film on an appropriate substrate or impregnating a heat-resistant porous body and firing it.

The amount of the whisker used in the method of the present invention is not particularly limited as long as the properties of the metal oxide serving as the matrix are maintained and the effect of the whisker is exerted. The amount is selected within the range of 1 to 100 parts by weight, preferably 5 to 50 parts by weight, per 100 parts by weight of the generated metal oxide.

In this way, when formed into a fibrous form,
Whiskers are oriented in the fiber axis direction, and a metal oxide sintered body fiber having a uniform distribution in the fiber can be obtained,
When formed into a thin film, whiskers are oriented in the plane direction of the film, and a metal oxide sintered body thin film uniformly dispersed in the film can be obtained. Furthermore, when the pores in the porous body are filled, a metal oxide sintered body composite in which whiskers are uniformly dispersed is obtained.

[0015]

According to the method of the present invention, unlike the conventional method of mechanically mixing a metal oxide powder and a whisker and firing the metal oxide powder, the metal oxide powder has a finely controlled particle size. It is not necessary to manufacture the whisker, and the whisker can be uniformly dispersed with excellent mechanical strength. Furthermore, since whiskers have the property of forming lumps, in the conventional method, when metal oxide powder and whiskers are mechanically mixed, it is necessary to wet-mix them, but due to moisture such as oxide superconductors, In the case of an oxide that is easily degraded, the wet method cannot be used, so that it is difficult to uniformly mix the whisker and the oxide powder. On the other hand, according to the method of the present invention, a metal oxide composite in which whiskers useful as a superconductor material are uniformly dispersed can be obtained without such a problem.

[0016]

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

Example 1 2.4 g of copper nitrate was dissolved in 50 ml of distilled water, and an SiC whisker (diameter 0.5 μm, length 10 μ) was added to this aqueous solution.
0.5 g was added and stirred to disperse uniformly. Next, the above-mentioned SiC was added to an aqueous sodium hydroxide solution obtained by dissolving 0.8 g of sodium hydroxide in 50 ml of distilled water.
A copper nitrate aqueous solution in which whiskers were dispersed was added with stirring to prepare a precipitate of copper hydroxide in which SiC whiskers were uniformly dispersed.

Next, the precipitate is collected by filtration using filter paper, washed several times with distilled water, dried, and then baked at 800 ° C. to obtain a copper oxide sintered body in which SiC whiskers are uniformly dispersed. Obtained.

FIG. 1 is a photomicrograph of the copper oxide sintered body. From this figure, it can be seen that SiC whiskers are uniformly dispersed in the copper oxide.

[Brief description of the drawings]

FIG. 1 is a micrograph showing the structure of a copper oxide sintered body in which SiC whiskers obtained by the method of the present invention are uniformly dispersed.

Claims (4)

(57) [Claims] In producing a sintered body of a metal oxide containing whiskers, whiskers are uniformly dispersed in a metal compound capable of forming a metal oxide by firing, and then the whiskers are fired. For producing a whisker-containing metal oxide sintered body. 2. In producing a sintered body of a metal oxide containing whiskers, whiskers are dispersed in a metal compound capable of producing a metal oxide by firing, and molded.
A method for producing a whisker-containing metal oxide sintered body, characterized by firing this. 3. The metal compound capable of forming a metal oxide upon firing is at least one selected from metal hydroxides, carbonates, bicarbonates, nitrates, and organic acid salts. Or the production method according to 2. 4. The method according to claim 1, wherein the metal compound capable of forming a metal oxide upon firing is a metal oxyacid salt.