KR20010077622A - Forming of Ceramics Using Agar - Google Patents

Abstract

PURPOSE: A ceramics forming method using agar is provided, which does not need any equipment and enables to form large-sized ceramics with complicated shapes due to high forming density. CONSTITUTION: The method is as follows: preparing slurry by ball-mixing ceramic powder, as oxide(Al2O3, Sic, Si3N4, etc.) or non-oxide, 1wt.%(based on the ceramic powder of dispersant and water to be 50-62vol% of solid content; adding 0.5- 10wt.%(based on the total amount of ceramics powder) of agar; ball-mixing for 2hrs. again; molding and heating a mold to 60-90deg.C for polymerizing agar; demolding and solidifying at room temperature.

Description

Forming of Ceramics Using Agar}

The present invention relates to a method of molding a large-scale complex ceramics, and more particularly, high molding density by using a wood starfish that is easily dispersed in low temperature water and can form a three-dimensional polymer chain at 60 to 90 ° C. It relates to a method of producing a ceramic molded body.

In the conventional case, ceramic molding is a hydrostatic molding in which a dry powder is charged into an elastic mold and then subjected to hydrostatic pressure, and a slurry prepared by mixing and dispersing the ceramic powder with a dispersant is injected into a porous gypsum mold such as a plaster mold. Injection molding to dry using capillary force, press injection molding to increase the osmotic pressure by increasing pressure in order to increase the molding rate, and adding about 30 wt% binder by weight ratio of ceramic powder. A plastic fluid having a relatively high viscosity is prepared, and then injected into a mold by applying pressure to form a mold, followed by degreasing binder, followed by mixing and dispersing ceramic powder in an injection molding organic monomer solution. Polymerization by injecting one slurry into mold of desired shape It was prepared by a method such as gel cast (Gel casting).

Hydrostatic pressure molding method is not possible to continuous process, there is a problem in mass production process application, and expensive equipment must be used. The injection molding method changes the characteristics of the molded body sensitively depending on the conditions of the slurry and the drying environment, so that the yield of the molded body is low and the processing time is long. In addition, the molding mold has to be replaced frequently, the density gradient occurs in the molded body, and the molding strength is low. In manufacturing large parts, there are problems such as cracking and collapse. The press injection molding method can obtain a denser compacted body in a relatively short time than the injection molding method, but it does not solve the problems such as density gradient and low molding strength in the molded body, which is a fundamental problem of injection molding. Injection molding uses a large amount of organic binder, which requires a long time in the degreasing process, and in the case of thick moldings, the disadvantage of being destroyed during degreasing and the difficulty of completely removing the pores left after degreasing in the subsequent sintering process, in addition to pressing metals There is a disadvantage in that a large cost is required to manufacture the mold. Gel casting can be molded regardless of the mold material such as metal, glass, plastic, etc., and it is relatively easy to remove various process additives added by 15 wt%, which has many advantages over other forming methods when forming a large member of complex shape. However, industrial applications have been limited due to the toxicity of acrylamide, which is a major component of gels. Recently, studies on non-toxic or low-toxic gel components have been progressed, but there are disadvantages in that the cost is high and the various components must be combined at an optimal ratio for the raw material powder.

The present invention has been made to solve the above problems, and an object thereof is to provide a ceramic molding method having a high molding density using a non-toxic and inexpensive process additive.

The new molding method to be developed should be easy to make a slurry without using special equipment by using two kinds of inexpensive non-toxic additives.

That is, an object of the present invention is to inject a slurry of uniformly dispersed low cost non-toxic processing additives in ceramic powder into the mold at room temperature to form a wood starch polymer chain at 60-90 ° C. and then solidify again at room temperature. The present invention provides a method of manufacturing a complex ceramic molded body having a molding density.

1 is a flow chart of alumina molded article manufacturing process according to the present invention

2 is an alumina molded body according to the present invention

In order to achieve the above object, the present invention is to add a fine starch and dispersant to the oxide or non-oxide ceramic powder such as alumina, silicon carbide, silicon nitride, and the like, the slurry is uniformly mixed and dispersed into the mold and heated to the wood polymer chain After forming, solidified at room temperature, demolded and dried in a thermo-hygrostat to prepare a ceramic molded body.

On the other hand, Figure 1 is a process flow diagram showing a process for producing a ceramic molded body according to the present invention. The present invention will be described in detail with reference to FIG. 1 as follows. First, distilled water is added to an oxide or non-oxide ceramic powder of alumina, silicon carbide, silicon nitride, etc. at room temperature so that 1 wt% of Davan-C (or SN5468), a dispersant, and a powder content of the slurry in the slurry are 50 to 62 vol%. Ball mixing for 24 hours. Thereafter, 0.5 to 10 wt% of a pellet was added to the ceramic powder, followed by ball mixing for 2 hours to uniformly mix and disperse the air, and then remove the air in the slurry using a vacuum pump. The prepared ceramic powder slurry is injected into various molds of a desired shape, and the mold itself is heated to 60 to 90 ° C. to form a wood chain molecular chain, and then solidified at room temperature, demolded, and dried by controlling humidity and temperature in a constant temperature and humidity chamber. A molded article was prepared.

EXAMPLE

To prepare the alumina molded body, distilled water was added to the alumina powder (> purity 99.8%, average particle size 0.5 μm, Sumitomo) so that 1 wt% of Davan-C dispersant and solid content were 55 vol% based on the weight of the alumina powder, and the alumina ball The mixture was dispersed and mixed in a polyethylene stirring tube for 24 hours by ball mixing to prepare a homogeneous slurry. Then, 1 wt% of starfish was added to the alumina powder, mixed and dispersed for 2 hours, and the vacuum pump was Air bubbles in the slurry were removed and then injected into the plastic mold. The mold itself was heated to 90 ° C. to form a lodge chain, and then solidified at room temperature. At this time, the ceramic powder and the moisture in the slurry are fixed by a loot molecular chain to maintain a desired shape. After demolding to remove the moisture in the thermo-hygrostat to prepare a molded body.

After measuring the molding density of the molded body, the test piece was processed according to the KS L 1591 standard and the molding strength of the molded body was measured by the bending strength measuring method. Molding density was 2.31 g / cm 3, about 60% of theoretical density, and molding strength was about 2 MPa.

In FIG. 2, an alumina turbocharger molded body prepared by a molding method using wood starfish is shown.

As described above, the present invention is a method of molding a ceramic using a wood starfish, which produces a slurry at room temperature, injects it into a mold, and heats it by using only a small amount of process additives without special equipment. There is an advantage that can easily mold large ceramics of the shape.

Claims (2)

In the manufacture of large-scale complex shaped ceramic molded body, a slurry prepared by adding a pellet to ceramic powder at room temperature is prepared, injected into a mold, and the mold is heated to 60 to 90 ° C. to form a pellets polymer chain, and then solidified at room temperature to form a ceramic molded body. Method for producing a The method according to claim 1, wherein 0.5 to 10 wt% of wood starch is added to the ceramic powder during the forming of the oxide-based or non-oxide-based ceramics.