JP2968626B2 - Casting method and casting mold for ceramics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for casting a ceramic using a split water-absorbent mold and a mold for molding. In particular, the present invention can prevent non-uniform ingrowth at the joint portion of the split mold, can obtain a uniformly inlaid molded body, and can obtain a molded body in which cracks do not occur in the drying and firing processes. The present invention relates to a novel method for casting and forming ceramics and a mold for forming the same.

[0002]

2. Description of the Related Art Cast molding of ceramics is generally performed by:
A method of using a split gypsum mold, injecting ceramic slurry into the gypsum mold, absorbing water into the gypsum mold, and molding the gypsum mold is adopted. However, in the conventional molding method, there is a problem that a concave portion is formed without being uniformly deposited at a joint or a joint portion of the split gypsum.

[0003] The formation of such recesses causes irregular internal stress during drying and firing, which also causes bending and cracking. Further, even if no crack occurs, this portion is thin due to the formation of the concave portion, and a line appears on the appearance, which is not preferable.

[0004] In order to uniformly coat the joints or joints of the split mold, that is, as a method of accelerating the deposition at the joints of the split mold, a conductive electrode is provided at the joint of the split mold and formed. A method has been proposed in which a voltage is sometimes applied to simultaneously perform the inking by electrophoresis (see Japanese Patent Application Laid-Open No. S60-151003).

[0005]

However, in the method of providing a conductive electrode at the joint of the split mold and applying a voltage at the time of molding, a direct current power supply,
Equipment such as electrodes immersed in slurry is required, and
There is a disadvantage that it takes time and effort to form an electrode at the joint of the split mold.

[0006] Further, when the hollow elongated molded body is formed of a closed gypsum mold, it is difficult to hold an electrode immersed in a slurry, and furthermore, a composite of two or more ceramics having different surface potentials. When molding a material, there is a problem in that the difference in the potential causes a difference in the deposition by electrophoresis, resulting in a non-uniform composition.

The present invention has been made in view of such inconvenience, and has been developed in order to eliminate the non-uniformity of the inlay at the joint portion of the split mold, and to provide a novel ceramic for promoting uniform inlay. An object of the present invention is to provide a casting method, and to provide a casting mold suitable for the casting method.

[0008]

The present invention is characterized in that a split-type water-absorbent mold is used, and the above-mentioned mold is used in which a tubular body having a vent hole is embedded in a joint portion of the split mold. Thus, the unevenness of the inlaid portion at the joint portion of the split mold is eliminated, and a molded body that is uniformly inlaid is obtained. That is, the present invention relates to a method for casting a ceramic using a split mold water-absorbing mold, wherein a tubular body having an air hole is buried at a joint portion of the split mold, and the tubular body having the air hole is inserted through the tubular body having the air hole. Vacuum suction, and
A method of casting and molding a ceramic characterized by removing an aqueous or organic dispersion medium of a slurry, and in a split mold water-absorbent mold, a tubular body having a vent at a joint portion of the split mold. This is a casting mold for ceramics, which is embedded.

The present invention will be described below in detail. As described above, the present invention uses a water-absorbing split mold in which a tubular body having an air hole is buried at a joint portion of the split mold. As the tubular body having the ventilation hole, any material having a ventilation hole or a ventilation path, such as a fiber tubular body or a resin tubular body having a ventilation hole, can be used. In the present invention, the outer diameter of the vent of the tubular body is preferably 100 μm or less. If it exceeds 100 μm, the ceramic raw material powder enters the air holes,
It is not preferable because it causes clogging.

The means for embedding this tubular body in a water-absorbent split mold will be described. After the split mold is manufactured, a groove having a shape matching the tubular body is formed by machining at the joint of the split mold. A method of embedding the tubular body in the groove, a method of arranging the tubular body in a predetermined mold, then pouring and solidifying a mold material, removing the mold, and the like are exemplified.

Next, the molding method of the present invention will be described. In the present invention, the aqueous or organic dispersion medium of the slurry at the joint portion is removed by vacuum suction through the tubular body having the above-mentioned vent hole. This vacuum suction can be performed using a normal vacuum pump, and the vacuum pump used for vacuum defoaming of the slurry can also be used as it is.

Examples of the ceramic raw material powder in the present invention include alumina, zirconia, silicon carbide, silicon nitride, and sialon. These ceramic powders are used as main components, and other materials (for improving characteristics) are used. (For example, ceramic whisker, carbon fiber, etc.)
Can be used, and this is also included in the present invention.

[0013] The molded article obtained by the molding method of the present invention is fired to obtain a sintered ceramic product. The method of firing the molded article can be performed by a conventional method. For example, normal pressure sintering, gas pressure sintering, HP, HI
A ceramic sintered product is manufactured using conventional means such as P.

[0014]

Next, an embodiment of the present invention will be described in detail with reference to FIGS. (Casting Mold) FIG. 1 is a plan view of a casting mold suitable for carrying out the molding method of the present invention.
FIG. 2 is a perspective view seen from a cross section taken along line AB of FIG. 1. As shown in FIGS. 1 and 2, this casting mold uses a cylindrical split-type gypsum mold 1 as a water-absorbent mold, and has a tubular shape having a vent hole at the split mold joint portion of the gypsum mold. Body 2
Buried structure. In FIGS. 1 and 2, reference numeral 3 denotes an inlaid molded body.

More specifically, the casting mold for casting is described below. The tubular body 2 having a vent hole is a hose-like tubular body having an outer diameter of about 2 mm made of fiber.
The vent preferably has an outer diameter of about 100 μm or less. A groove having a shape conforming to the tubular body 2 is provided on the other mold surface opposite to the one mold surface on which the tubular body 2 is provided, so that no gap is formed at the joint of the molds. To be designed. Further, the gypsum mold 1 in which the tubular body 2 is embedded can be produced by disposing the tubular body 2 in a predetermined mold, casting and solidifying a gypsum slurry, and removing the mold. Then, a vacuum pump (not shown) is connected to the tubular body 2 having the ventilation holes so as to remove water present at the joint portion.

(Cast Forming Method) Next, an embodiment of the cast forming method of the present invention will be described. A sialon slurry was used as a cast forming slurry.
This sialon slurry is made of sialon powder “Si _5.5 Al _0.5 O _0.5 N _7.5 (Z = 0.5)” having an average particle size of 0.5 μm.
Parts by weight and 40 parts by weight of ion-exchanged water are placed in a resin ball mill, and 0.5 parts by weight of polyoxyethylene alkylphenyl ether and ammonium polycarboxylate are added as peptizers thereto and mixed for 18 hours. In this way, it was produced.

The plaster mold 1 composed of two split molds used was a cylindrical one having a diameter of 30 mm and a length of 50 mm.
The slurry was poured into the mold, pressurized at ² kg / cm ² , and at the same time, vacuum was adjusted to −760 mmHg by a vacuum pump connected to the tip of the tubular body 2, and vacuum suction was performed. Then, after the slurry was immersed for a predetermined time, the slurry was discharged to obtain a hollow tubular sialon molded body. In the obtained sialon molded product, no difference was observed between the thickness of the molded product corresponding to the joint portion of the gypsum mold 1 and the thickness of the other portions, and it was confirmed that this molding method was effective. . Also, no cracking or deformation occurred after drying and firing.

[0018]

As described in detail above, the present invention uses a water-absorbent split mold in which a tubular body having an air hole is buried at the joint of the split mold, and is provided through the tubular body having the air hole. To remove the aqueous or organic dispersing medium of the slurry at the joints of the split mold, and thereby to remove the inking at the joints (joints) of the split mold. The effect of eliminating the non-uniformity and obtaining a molded body having a uniform thickness is obtained. That is, according to the present invention, it is possible to obtain a homogeneous molded body having a reduced density difference between the seam portion of the split mold and the other portions, and therefore, it is possible to obtain a molded body that does not generate cracks in the drying and firing processes. A possible effect occurs.

According to the present invention, no special equipment is required in addition to the ordinary casting apparatus, and it is not necessary to immerse the electrodes in the slurry injected into the gypsum mold or to hold the electrodes. Further, when forming a composite material of two or more types of ceramics, there is no need to worry about the difference in the surface potential, and a molded body having a uniform composition can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of a casting mold suitable for carrying out the present invention.

FIG. 2 is a perspective view as viewed from a cross section taken along a line AB in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Split gypsum mold 2 Tubular body which has an air hole 3 Infill molding

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B28B 1/26 B28B 1/14

Claims (3)

(57) [Claims] 1. A method for casting a ceramic using a split mold water-absorbent mold, wherein a tubular body having an air hole is buried in a joint portion of the split mold, and a vacuum is inserted through the tubular body having the air hole. A method for casting a ceramic, comprising suctioning and removing an aqueous or organic dispersion medium of the slurry at the joint portion. 2. A casting mold for ceramics, wherein a split-shaped water-absorbent mold is formed by burying a tubular body having an air hole in a joint portion of the split mold. 3. The casting mold for ceramics according to claim 2, wherein the split mold water-absorbing mold is a split gypsum mold, and the tubular body having vent holes is a fiber hose-shaped tubular body. .