JPH0445322B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to an effective method for manufacturing carbon parts having complex shapes, particularly thin-walled or thin-film carbon parts.

(b) Technical background Carbon materials are electrically conductive materials with excellent heat resistance, chemical stability, high-temperature strength, etc.
Widely used in electronic components, heat-resistant materials, catalyst carriers, etc.

Recently, the need for thin-walled parts with complex shapes has been increasing as electronic materials and electrode materials.

Carbon materials are usually produced by bonding carbon powder with pitch, resin, etc. and then firing it, or by compression molding sinterable carbon powder and then firing it.

Furthermore, in order to produce a high-density carbon material, the fine pores generated during firing are impregnated with pitch or the like and firing is repeated.

Therefore, it is difficult to make parts with complex shapes, especially thin parts, and currently they are manufactured by machining using materials made by the above method.
It also has the disadvantages of low material yield and breakage during processing.

Another conventional method is to set the viscosity of a polar solvent within a certain range to impart an electric charge to the ceramic material powder, and then deposit the ceramic material powder onto a support by electrophoresis. It is being

However, in this conventional method, the ceramic material powder itself does not have an electric charge, and the method of imparting an electric charge to it involves specifying the viscosity, boiling point, dielectric constant, and saturated vapor pressure of the solvent. The disadvantage is that the range is narrow and raw material powders cannot be freely combined without selecting a solvent.

Moreover, it also has the disadvantage that the electrophoretic properties of the ceramic material powder are greatly influenced by changes in the viscosity and other values of the solvent.

(C) Disclosure of the Invention This invention was made to solve the various problems mentioned above in the production of carbon parts using conventional techniques, and it involves adding an ionizable carrier to uncharged carbon powder particles. By kneading and adhering a third substance, the electrophoretic properties of the raw material powder can be greatly improved, and the raw material powder can be turned into a liquid (solvent).
Can be combined without selection, complex shapes,
It is an object of the present invention to provide a manufacturing method that can efficiently manufacture particularly thin carbon parts.

That is, in order to make a carbon part of a desired shape and uniform thickness, this invention first prepares a conductive base material of the desired shape, and applies the principle of electrophoresis to create a uniform carbon part on the base material. The main idea is to form a carbon powder layer.

According to the method of the present invention using electrophoresis, powder is made into a slurry and dehydrated and deposited on a porous base material.Instead of simply physical slurry adhesion as in the mud-casting method, carbon is irreversibly deposited. A powder layer can be formed on the substrate.

The method of this invention will be explained in detail below.

First, since the method of this invention deposits carbon powder on a base material by electrophoresis, the base material itself is conductive or has its surface treated to be conductive. It is necessary.

And in order for a powder particle to be electrophoresed in a liquid, it must become electrically charged in the liquid.

Since the carbon powder particles themselves do not ionize, a charged carrier is attached to the carbon powder particles, and the carbon powder particles are simultaneously migrated by electrophoresis of the carrier.
A carbon powder layer is formed on a base material.

As described above, according to the method of kneading and adhering an ionizable carrier to carbon powder particles in a liquid, the kneaded carbon-carrier becomes electrically charged in the liquid, and electrophoresis is significantly improved. Therefore, there is an advantage that the kneaded material can be more quickly and densely deposited on the substrate.

The carrier used at this time may be any carrier as long as it adheres to the carbon powder particles and can be ionized in the liquid. However, it is undesirable to prevent the sintering of the carbon powder material after it has been electrophoretically deposited on the substrate.

As such a carrier, polycarboxylic acid resins (anionic), polyamine resins (cationic), etc., which are used in ordinary electrodeposition coatings, can be used.

This carrier can serve as a primary binder for the carbon powder particles, but a primary binder component may also be added to the carrier.

The carbon powder that is the main raw material powder in this invention is
Needs to be sufficiently miniaturized, practically 40μm
It is preferable to use the following particle sizes. The carbon powder may be used alone, or a boron compound such as boron oxide or boron carbide may be used as a sintering aid, or powder of ceramics such as silicon carbide or silicon nitride may be used to improve strength and oxidation resistance. can be used in combination and deposited simultaneously.

Further, according to the method of the present invention, bath liquids in which powder particles having different components are dispersed are prepared separately, and electrodeposition is performed in stages using these bath liquids, thereby forming a deposited layer in which layers having different components are laminated. It is also possible to manufacture

Furthermore, since this solution (solvent) does not impart an electric charge to the carbon powder particles, it is possible to freely combine raw material powder particles without selecting a solution.

In addition, since the deposited layer of carbon powder has conductivity,
It is possible to apply electricity in a bath liquid in a state separated from the base material, and further to laminate various deposited layers.

The deposited layer of carbon-carrier thus deposited on the substrate is then washed, dried, separated from the substrate, and then carbonized and fired.

When a heat-fusible or thermosetting resin is used as a carrier, the resin is heated to heat-fuse or heat-cure after washing and drying, thereby increasing the mechanical strength of the carbon-carrier layer and forming a base material. It can be easily handled during peeling, firing, etc.

Furthermore, since electrophoretic deposition occurs only on electrically conductive parts of the base material, if a part of the base material is intentionally covered with an insulating film, the carbon-carrier mixture will not be deposited on that part. Utilizing this fact, it is possible to apply an insulating film in an arbitrary pattern on a base material to form a deposited layer of a patterned carbon-carrier kneaded material.

As mentioned above, after the carbon-carrier kneaded material is deposited on the base material, the base material is separated, and the deposit is carbonized and fired, but this will be explained in more detail. After a carbon-carrier kneaded material is deposited on a substrate, it is heated to 300 to 1000°C to decompose or volatilize the carrier component in the deposited layer.

Thereafter, before sintering the deposited layer, the deposited layer is separated from the base material and then sintered under normal pressure or pressure in the range of 1000 to 2000°C.

Note that the separation of the base material from the deposited layer is not limited to the above-mentioned process before sintering the deposited layer, but may be performed by applying a mold release agent or the like that prevents adhesion to the deposited layer electrodeposited on the base material in advance. Alternatively, a method may be used in which the base material is separated after final sintering to form a sintered body, whereby a thin-walled carbon part can be obtained.

In addition, as a method for separating and removing the deposit layer and the base material,
As mentioned above, it is easy and preferable to perform a mold release treatment on the base material in advance and then mechanically separate it, but there are also methods of melting, decomposing, and volatilizing it by heating, dissolving it with chemicals, or using electricity. Methods such as chemical separation are possible, and these may be adopted depending on the purpose. For example, conductive treated wax, melting resin, or low melting point metals can be removed by heating and melting, carbon materials, organic compounds, etc. can be separated and removed by heating and oxidizing, and metals are generally separated and removed by acid treatment, etc. be able to.

Note that the carrier component used with the carbon powder is decomposed or volatilized from the deposited layer as described above, so a material that does not leave any decomposition residue or a material that does not have a negative impact on the final sintered body should be selected and used. It is preferable.

In addition, 300 ~
The atmosphere during heating to 1000°C may be arbitrarily selected from air, oxygen, inert gas, etc.

When separating the base material and the deposited carbon-carrier layer, if the product has a three-dimensional shape and cannot be separated from the base material by peeling, the base material may be made of metal and chemically applied. It can be separated using methods such as using wax that is dissolved with chemicals or subjected to conductive treatment as a base material, and removing it by melting and volatilizing it with heat.

This will be explained in detail below using examples.

Example 5% by weight of each of silicon carbide powder and boron carbide powder was blended with coke powder having self-sintering properties, and this was further finely pulverized to obtain carbon material powder with an average particle size of 2 μm.

This powder was thoroughly kneaded with an acrylamide resin as a carrier, and then dispersed in a bath liquid.

Next, a stainless steel plate with a very thin coat of conductive grease on its surface was used as a cathode, a stainless steel plate without such treatment was used as an anode, and a kneaded material made of the carbon material powder and acrylamide resin was dispersed in these. The cathode plate was immersed in the bath solution, and a voltage of about 200 V was applied for about 10 minutes while thoroughly stirring and mixing the bath solution to form a kneaded material layer with a thickness of about 300 μm on the cathode plate.

Thereafter, the stainless steel plate on which this kneaded material layer was formed was thoroughly washed with water and dried, and the carrier resin was baked at 170° C. for 20 minutes to form a carbon film layer, and then the stainless steel substrate was removed from the carbon film layer.

The thin plate made of the carbon film thus obtained was
After firing at ℃ for 1 hour to remove volatile matter, the temperature was gradually increased to 2000℃ under an inert gas atmosphere to sinter the thin plate, and a dense and uniform thin carbon material was obtained. Ta.

Claims (1)

[Scope of Claims] 1. A carrier that can be ionized in a liquid is kneaded with sinterable carbon or a fine powder mainly composed of carbon, or a raw material powder prepared by mixing this with a sintering aid, a binder, etc., After attaching the carrier to the raw material powder particles,
This is dispersed in a liquid, and a DC voltage is applied between a conductive base material immersed in the liquid and a counter electrode to deposit a kneaded material of carbon-carrier on the conductive base material. 1. A method for manufacturing carbon parts, which comprises removing a base material from a carbon-carrier deposit, carbonizing, decomposing, and volatilizing the support in the deposit by heating, and then firing and sintering. 2. The carbon component according to claim 1, which uses a conductive base material that has been subjected to a mold release treatment in advance to facilitate release from electrodeposited deposits on the base material. Production method. 3. The method for manufacturing a carbon component according to claim 1, wherein the base material is removed by melting, decomposing, and volatilizing by heating. 4. The method for manufacturing a carbon component according to claim 1, wherein the base material is removed by dissolving or decomposing it by chemical or electrochemical treatment. 5. The method for manufacturing carbon parts according to claim 1, wherein the carrier is a water-soluble or water-dispersible synthetic resin that can be ionized in a liquid. 6. The method according to claim 1, characterized in that a deposit layer is partially formed using a conductive base material partially coated with an insulating material to obtain a deposit layer with a desired pattern. Method of manufacturing carbon parts. 7 When forming a deposit layer on a conductive substrate, electrodeposition is performed sequentially using solutions with stepwise changes of components while maintaining the conductivity of the deposit layer, and deposited substances with different components are formed in layers. 2. A method of manufacturing a carbon component according to claim 1, characterized in that: