JPS61182902A - Manufacture of ceramics product - Google Patents

Abstract

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

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing ceramic products.

The present invention can be utilized, for example, when manufacturing thin-walled ceramic products having hollow parts.

[Prior Art] As a manufacturing method for ceramic products, there has been proposed a manufacturing method in which a molded body is formed by a rubber press method, a hot press method, etc., and the molded body is fired. It was difficult to manufacture products.

Therefore, the present applicant has recently developed ceramic powder on the surface of the mold electrode by immersing the mold electrode in a solution containing ceramic powder charged with a surfactant and applying a DC voltage to the mold electrode. a first step of electrodepositing the ceramic layer to form a ceramic layer; heating the mold electrode on which the ceramic layer is electrodeposited to separate the mold electrode from the ceramic layer by melting or the like; and a second step of firing the ceramic layer. We have developed a manufacturing method consisting of two steps (unknown at the time of this application).

[The invention tries to solve 1/! [Problem 1] According to the manufacturing method described above, thin-walled ceramic products having a hollow portion can be easily manufactured. However, since this manufacturing method usually uses a mold electrode made of metal, metal ions are likely to be eluted from the mold electrode into the solution during electrodeposition. Therefore, there was a problem in that the metal ions became nucleated and the ceramic powder in the solution agglomerated.

In addition, metal ions are included in the ceramic layer due to adhesion of metal ions to the mold electrode along with the Hiramix powder, resulting in a problem in that the firing strength of the fired ceramic product is reduced.

The present invention solves the above-mentioned problems, and provides a manufacturing method that can prevent metal ions from eluting from the mold electrode, suppress agglomeration of ceramic powder, and reduce the firing strength of ceramic products. be.

In the manufacturing method of the present invention, a carbonaceous material is introduced into a solution containing charged ceramic powder! A first step of immersing a mold electrode having a certain surface shape as a base material and applying a DC voltage to the mold N pole to electrodeposit ceramic powder on the surface of the mold electrode to form a ceramic layer. and a second step of separating the ceramic layer from the mold electrode by central removal or combustion of the mold electrode, and firing the ceramic layer.

In the first step, a mold electrode having a constant surface shape and made of a carbonaceous material as a conductive base material is immersed in a solution containing charged ceramic powder, and a DC voltage is applied to the mold electrode. This step is generally carried out by immersing the mold electrode and the other electrode in a solution and applying electricity between the two electrodes. As a result of applying a DC voltage as described above, the charged ceramic powder particles migrate in the solution and are deposited on the surface of the mold electrode, thereby forming a ceramic layer on the surface of the mold electrode. . The thickness of the ceramic layer varies depending on the type of ceramic product, but is generally 0.2 to 2.
It should be approximately 0 mm.

Electric charge can be imparted to the ceramic powder by adding the ceramic powder and a surfactant to the solution. As the surfactant, anionic surfactants and cationic surfactants can be used. In addition to these surfactants, nonionic surfactants may be added. As a surfactant, for example, Kaoite #i
! Emar TD manufactured by Co., Ltd., Amogen manufactured by Daiichi Kogyo Seishin Co., Ltd., 1 Neugen ET (II registered trademark), etc. can be used.

When ceramic powder and an anionic surfactant are added to the solution, the particles of the ceramic powder are given a large electric charge, so when a DC voltage is applied, the particles of the ceramic powder move toward the anode. . Therefore, in this case, the mold electrode is used as an anode.

Furthermore, when ceramic powder and a cationic surfactant are added to the solution, the particles of the ceramic powder are positively charged by the cationic surfactant, so that the particles move toward the cathode. Therefore, in this case, the type electrode is used as a cathode. Note that when a surfactant is attached to the ceramic powder particles, the ceramic powder particles can be easily dispersed in the solution due to the action of the surfactant.

As the ceramic powder, commonly used oxide-based, nitride-based, carbide-based, etc. can be used. For example, silicon nitride, silicon carbide, titanium carbide, aluminum nitride, aluminum oxide, magnesia, silica, etc. can be used. The average particle size of the ceramic powder can generally be from 0.05μ to 50μ, preferably around 1μ.

This is because the degree of suspension of the ceramic powder can be increased.

It is preferable to add a sintering aid to the solution together with ceramic powder and a surfactant. As a sintering aid
03, MGO, Yt 03(7) and others SiO2, La
Ox, Ce2O3, CaO, etc. can be used to produce irco. In particular, about 1 to 50% is preferable. For example, when manufacturing silicon nitride ceramic products, △
1 to 30% of 1Y, MOIBe oxide, etc. is used.

The type electrode that characterizes the present invention is an electrode that uses a carbonaceous material as a conductive base material and has a constant surface shape.

Graphite is a typical carbonaceous material.

In this case, both artificial graphite and natural graphite can be used.

Further, as the carbonaceous material, at least one of carbon fiber and carbon powder having conductivity can be used.

In this case, the mold electrode can be made of a material such as CFRP, which is a mixture of resin and at least one type of carbon 11 and carbon powder. In this case, the carbon fiber preferably has a diameter of about 0.1 to 30 μm. Further, the carbon powder preferably has a diameter of about 0.01 to 5 μm. C.F.
When the mold electrode is made of RP, the mold electrode is strengthened, so damage when removing the mold electrode can be suppressed, and the same mold electrode can be removed and used many times. . In order to facilitate removal, it is also preferable to match the orientation direction of the carbon m miscellaneous with the removal direction of the mold electrode. As the resin mentioned above, a thermosetting resin or a thermoplastic resin can be used.

When using thermoplastic resin, heating the mold electrode will result in
As the resin is plasticized, it becomes, for example, liquid, so that it is easy to separate the mold electrode and the ceramic layer. Therefore, it is suitable for cases with a reverse taper and a complicated shape that are virtually impossible to remove.

The size and proportion of carbon fiber and carbon powder are
It is set appropriately depending on the conductivity required by the mold electrode, the type of ceramic product to be manufactured, etc.

The mold electrode has a surface shape that is variously set depending on the shape of the ceramic product to be manufactured. For example, the type electrode can be shaped like a cone, a truncated cone, a sheet, a cylinder, a truncated pyramid, a prism, or the like. It is preferable to form a tapered portion in the mold electrode, as exemplified in the examples described later. Also, keep the surface of the tapered part of the mold electrode smooth;
It is also preferable to configure the mold electrode with a plurality of electrode bodies that are divided in advance. In this way, the carbonaceous material has high lubricity and the mold electrode can be easily removed. Also,
The shape of the mold electrode may be the shape of the example shown in FIG. 2 depending on the case. In the case shown in FIG. 2, the type electrode 3
0 is composed of two pieces that can be separated from each other in the direction of the arrow X. If the mold electrode holder 7 is provided on the surface 30a and the surface 30b of this mold electrode 30, a cylindrical ceramic layer with openings on both sides can be formed. Can be formed.

The mold electrode may be solid or hollow. When the mold electrode is made hollow, it becomes possible to lower the electric resistance value of the entire mold electrode, and when the mold electrode is burned in the second step,
Since the amount to be burned is reduced accordingly, combustion can be made easier.

In some cases, the mold electrode may be composed of a main body mainly made of a non-conductive material such as wax, and a conductive part formed from a carbonaceous material provided on the surface of the main body. In this case, by heating the mold electrode with the ceramic layer electrodeposited above the wax melting temperature, the main body can be melted and easily discharged.

In the first step, the type of tank for storing the solution, the type and temperature of the solution, the concentration of the solution, the current density, the other electrode, etc. are variously set as necessary. For example, the voltage is 40 to 4
00V can be used. Particularly good is 5o~200V. When the mold electrode is made of the above-mentioned CFRP,
The voltage can be 50-200V. Generally, a suitable electrodeposition time is 1 to 10 minutes. The counterpart electrode of the mold electrode may be any material as long as it is electrically conductive. For example, a tank that stores a solution may be used as the other electrode.

In this case, the thickness of the electrodeposited ceramic layer can be made more uniform.

Water is usually used as a solution to add ceramic powder, surfactant, etc., but this water is mixed with isopropyl alcohol,
Methanol, ethanol, and butanol may also be dissolved. The concentration of ceramic powder in the solution is preferably about 2 to 15% by weight. The reason for this is that it is advantageous in obtaining uniformity in liquid dispersion and uniformity in wall thickness of the molded body.

In the second step, the ceramic layer is separated from the mold electrode,
This is a step of firing the ceramic layer.

Typical separation means include removal of the mold electrode, burning of the mold electrode, destruction of the mold electrode, or a combination thereof.

If the mold electrode is provided with a tapered portion as described above, the work of removing the mold electrode from the ceramic layer becomes easy due to the inclination of the taper portion. Further, if the surface of the tapered part of the mold electrode is made smooth or if the mold electrode is composed of a plurality of electrode bodies, removal becomes easier. Note that one-friend withdrawal can be carried out, for example, as follows.

For example, a mold with a cavity corresponding to the outer surface of the ceramic layer is prepared, a mold electrode with a ceramic layer attached is set in the cavity of this mold, and only the mold electrode is gently moved to remove one layer from the ceramic layer. can do. To burn the mold electrode, for example, a combustion burner or an oxygen gas supply nozzle is inserted into a hollow part previously formed in the mold electrode, or into a recess or hole formed with a drill or the like in a later process, and the oxygen gas is supplied to the mold electrode. It is possible to explore means of burning the mold electrode using the combustion burner or the like while supplying the . Incidentally, the carbonaceous material forming the mold electrode may be burned together with the firing of the ceramic layer.

The firing temperature of the ceramic layer depends on the type of ceramic powder,
Although it varies depending on the thickness of the ceramic layer, etc., it is usually about 1600 to 2000°C.

In particular, about 1600 to 1800'C is good. Heating time is 1
~10 hours is good. For example, when silicon nitride is used as a ceramic powder, generally 2 to 5
Heat it for some time. The temperature increase rate is 0.5℃/min to 3℃/
About a minute is good. The temperature may be raised stepwise or continuously.

Specifically, the ceramic products obtained by the manufacturing method of the present invention are used for engine cylinder liners, ceramic ICs, etc.
It can be used for package sheets, cup-shaped containers with one end open, and cylindrical containers with both ends coated with Ul.

[Effects of the Invention] The manufacturing method of the present invention is characterized by using a molded electrode in which a carbonaceous material is used as a conductive filler. Therefore, according to the manufacturing method of the present invention, it is possible to prevent metal ions from eluting from the mold electrode. Therefore, it is possible to suppress the agglomeration of the ceramic powder in the solution caused by the metal ions that have conventionally been generated as nuclei. Furthermore, since metal ions are prevented from adhering to the ceramic layer, a decrease in strength when the ceramic layer is fired can also be suppressed.

[Example] In this example, a container-shaped thin ceramic product is manufactured.

First, 50 g of silicon nitride powder, 3 g of alumina powder, 3 g of magnesia powder, 3 g of ittria powder, 20 CG of isopropyl alcohol, and 1 q of anionic surfactant were added to 1000 cc of water in tank 1.

Then, the water is stirred to prepare a solution 2 in which the -F ceramic powder is dispersed. In this case, the average particle size of the silicon nitride powder is 0.1 to 2.5μ, the average particle size of the alumina powder is 0.1 to 2.0μ, and the average particle size of the magnesia powder is 0.1 to 2.0μ. And so. Moreover, specifically, Emar Shita D (trade name) manufactured by Naedo Soap Co., Ltd. was used as an anionic surfactant. Stirring of solution 2 was performed by motor stirring.

Then, in this solution 2, a molded electrode 3 having the shape of a molded body having a tapered portion 31 was immersed, and at the same time, the electrode plate 4 was immersed. In addition, 7 is a mold electrode holding part. It is preferable that no ceramic layer adhere to this type electrode holding portion 7. In this example, the mold electrode 3 is made of graphite as a carbonaceous material, and has a truncated conical shape having a tapered portion 31 that gradually becomes wider from the lower part 3a to the upper part 3b, as shown in the figure. In this state, the mold electrode 3 was set as the anode, and the electrode plate 4 was set as the cathode, and a DC voltage was applied between the two electrodes using a voltage 885.

In this case, the DC voltage was 70V and was applied for about 10 minutes.

As a result of applying a DC voltage in this manner, ceramic powder particles were electrodeposited and deposited on the entire surface of the mold electrode 3, and a ceramic layer 6 was formed. The thickness of the ceramic layer 6 is 0
．． It was set to 5 to 2 mm. In this example, solution 2
No particular agglomeration of ceramic powder was found inside.

Next, take out the mold electrode 3 from the solution 2, and remove the mold electrode 3 from the solution 2.
The moisture was removed by drying at 0° C. for 30 minutes.

Next, the mold electrode 3 is removed from the ceramic layer 6 and the mold electrode 3 is removed from the ceramic layer 6.
and ceramic layer 6 were separated. Specifically, withdrawal is
It was removed by appropriate vibration or by the vibration of the mold electrode 3 or the ceramic clay mix layer 6. After separation, the ceramic layer 6 is heated to 1600-1 in a nitrogen atmosphere in a heat treatment furnace.
The mixture was heated at 800° C. for 3 to 4 hours to perform firing, thereby forming a container-shaped ceramic product. The 1 m speed was 1°C/min to 1.5°C/min.

Test specimens were formed according to the examples described above.

The size of the test piece was 5 mm thick, 30 mm long, and 2 mm wide. The three-point bending strength of this test piece was then examined. Specifically, the three-point bending strength is J
15-R-1601r Fine Ceramics Bending Strength Test Method". As a result of the test, the three-point bending strength was 75 ka/mn2.

[Comparative Example] As a comparative example, a ceramic layer was formed in the same manner as in the above-described example using a type electrode made of e, Zn, and pb. Ceramic powder agglomerated in the solution. Analysis of the agglomerated ceramic powder revealed that Fe, Zn, Pb, etc. were eluted into the solution. For example, in the case of a type electrode made of Fe, 70 volts x 2 hours When electricity was applied under these conditions, 0.02 to 0.05% of Fe was eluted in the solution.

Therefore, the ceramic powder aggregated at the bottom of the tank 1 in the first step. This was not completely redispersed even with vigorous stirring.

As a comparative example, a test piece of the size shown in the example (Jf 5 mm,
30 mm in length and 5 mm in width). The three-point bending strength of this test piece was then examined. In this case, the three-point bending strength was 65 kO/llllR13, which was lower than the example using the graphite type electrode described above. This is considered to be because the Zn ions were eluted and remained in the ceramic layer, and were sintered while remaining.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of the present invention, and is a sectional view showing a state in which ceramic powder is electrodeposited on a graphite mold electrode. FIG. 2 is a cross-sectional view showing electrodeposition using different types of electrodes. 1... [2... Solution 3.30... Power restoration 4f! 4... Electrode plate 5... Power supply 6... Ceramic layer patent applicant
Toyota Motor Corporation Representative Patent Attorney Hirodo Okawa Patent Attorney Shudo Fujitani Patent Attorney Akio Maruyama

Claims (5)

[Claims] (1) A mold electrode with a constant surface shape made of a carbonaceous material as a conductive base material is immersed in a solution containing charged ceramic powder, and a DC voltage is applied to the mold electrode. A first step of electrodepositing ceramic powder on the surface to form a ceramic layer, and a second step of separating the ceramic layer from the mold electrode by removing or burning the mold electrode and firing the ceramic layer. A method for producing a ceramic product, comprising: The manufacturing method according to claim 1, wherein the (2) type electrode is formed using graphite as a conductive base material. (3) The manufacturing method according to claim 1, wherein the type electrode is formed using a conductive base material that is a mixture of at least one of carbon fiber and carbon powder and a resin. (4) The manufacturing method according to claim 1, wherein the type electrode has a tapered portion for removal. (5) Ceramic powder is one or more of silicon nitride, silicon carbide, titanium carbide, aluminum nitride, alumina, magnesia, and silica, and is charged with a surfactant. The manufacturing method according to claim 1, which is shaped like a container.