KR20030044733A - Manufacture technology of porous ceramics that use surfactant - Google Patents

Abstract

PURPOSE: Provided is a manufacturing method of porous ceramics for lightweight pottery and construction materials by adding surfactants to ceramic slurry for foaming, forming by slip casting, and sintering. CONSTITUTION: The porous ceramics are manufactured by the conventional process of preparation of slurry, foaming, forming, drying and sintering. The slurry with 30-60vol.% of solid(clay) and 100-400cps of viscosity is prepared by mixing ceramic powder(<=3micrometer) with water and stirring over 3hrs for dispersion. Then, the slurry is foamed by adding 0.5-13wt.% of anionic surfactant, heating to 80-120deg.C, and stirring for formation of pores having a 100-500micrometer size. The porous ceramics(100-250micrometer of pore) are manufactured by forming the slurry by slip casting, drying formed products and sintering over 1150deg.C.

Description

Manufacture technology of porous ceramics that use surfactant}

A porous body is a general term for what is used as various materials in the state which has many pores in the solid, regardless of the material of an inorganic material, an organic material, or a natural thing or an artificial thing. Here, porous ceramics {porous ceramics} exhibits various physical and chemical properties by the pore size, shape, porosity, and the like. In particular, ceramics are used in fields requiring high temperature and corrosion resistance because they have better heat resistance and corrosion resistance than organic or metal materials. Porous ceramics {porous ceramics} are closely related to daily life. Functionality such as light weight, soundproof, moistureproof, dustproof, and sound insulation in industrial fields, and precisely control the physical and chemical properties of the pores, and recently, to the separation, purification, ion exchange, catalysis, chemical reaction, etc. Usage is expanding gradually.

In particular, plastic products, which are heavy in ceramic tableware and ceramic building materials, have weak durability and emit pollutants, and are widely used in place of ceramics. However, due to the characteristics of the ceramic products described above, a lighter-weight ceramic product is required. .

There are many methods for producing such a lightweight ceramic, but the method of foaming the slurry and using the bubbles in the foam as pores is less restrictive of the starting material, the porosity of the plastic body can be easily adjusted, and the desired shape or reticulated porous body is also available. It can manufacture.

In the present invention, a porous ceramic, which is formed by foaming between ceramic powders by adding water and a surfactant to a ceramic powder by stirring and heating, by using foam as pores, produces porous ceramics {porous ceramics} It aimed at manufacturing a ceramic lightweight body.

The technical field to which the present invention belongs generally is that porous ceramics

In the manufacture of lightweight ceramics, which is an object of the present invention, a surfactant is added to a slurry and foamed by using a bubble in a foam as a pore to prepare porous ceramics. The physical properties were measured according to the concentration, and the changes in the heat treatment temperature and the foaming time were measured. Both the dried and calcined porous bodies exhibited porous body properties with homogeneous pore sizes of about 100 μm-500 μm. Other conventional techniques such as the polymer sponge method, the method of using the gap between the constituent particles by controlling the firing temperature, the method of using the space occupied by mixing the blowing agent or organic matter, the method using the lyophilization method, the foam in the foam by foaming the slurry The method of using pores has always been a problem because the porous body is relatively easily experimentally manufactured, but the pore size cannot be controlled and the pollution of the gas generated during combustion is always a problem. In particular, the manufacture of lightweight ceramics for tableware has not been attempted because slip casting, which is a sophisticated molding method, is almost impossible, but the method proposed by the author could solve this problem.

[Example 3] Pore formation during foaming and firing of slurry

Based on the foam slurry characteristics according to the surfactant {surfactant} concentration of Example 2, the dried specimens were calcined at a temperature of 1150 and 1200 ℃ to investigate the pore formation by SEM photograph, the temperature was increased, the surfactant {surfactant } As the concentration increased, the pore size became smaller and the distance between the pores became closer. In this experiment, the pore size in the surfactant {surfactant} 6.0wt% to form the optimum amount of foam was about 100 ~ 250㎛. Smaller pores were formed during firing than 200-300 μm pores in dried specimens.

In addition, the pores and pores are connected to each other through the window through the SEM image, it was confirmed that the continuous pores contained in the specimen.

[Example 4] Physical Characteristics

The physical properties of the fired specimens at different temperatures and with increasing surfactant {surfactant} are shown in Fig. Same as 3. The physical properties showed that all specimens were sintered as the temperature increased, so that the shrinkage and specific gravity increased, and the porosity and absorption decreased. On the other hand, the physical properties of surfactant {surfactant} increased, similar to the tendency of microstructural observation and compressive strength, the increase of surfactant {surfactant} increased porosity, water absorption, shrinkage, etc., and the specific gravity decreased. At concentrations above 6.0 wt%, the opposite trends were observed below 6.0 wt%.

[Example 1] Particle Size and Characteristics of Dispersion Slurry

The average particle size of the ceramic powder starting material used in the present invention was pulverized to about 3 μm when measured by sedimentation analysis. Since the raw material particles of the slurry form a framework of porous ceramics {porous ceramics}, as the particle size increases, the pore size generally increases. When the average particle size is about 3㎛, homogeneous pores of 100㎛-500㎛ Size was formed. The foaming force had a great influence on the viscosity of the slurry, but when the viscosity was low, the foaming force was excellent, but the stability of the formed foam was drastically lowered, and when the viscosity was high, the foaming force was not excellent. In this experiment, Brookfield's Model DV-II + Viscometer adjusted the viscosity of the slurry to about 100 cps to 400 cps and used it in the foaming process. The concentration of the prepared slurry was 100 μm-500 in the range of 30 to 60 vol% clay. It had a homogeneous pore of 탆.

[Example 2] Foaming Slurry Characteristics According to Surfactant {surfactant} Concentration

Fig. 2 shows the foaming time of the slurry according to the surfactant {surfactant} concentration. In this case, the foaming time refers to the time required for the foam amount to be doubled as the initial slurry. The reason why the foaming time is doubled as that of the initial slurry is that the concentration is not more than two times at low concentrations and not more than three times at high concentrations.

It can be seen that the foaming time of the slurry decreases until the concentration of the surfactant {surfactant} is 6.0wt%. That is, the surface tension of surfactant {surfactant} decreased as the concentration increased up to 6.0 wt%. However, above that, the foaming time was increased, and at 13wt%, the initial slurry was not doubled, because the viscosity of the initial slurry was increased by increasing the amount of surfactant {surfactant} above 6.0wt%. Therefore, the concentration of the surfactant {surfactant} which gives an optimum foaming amount with little influence on the initial slurry viscosity in the present invention was found to be 6.0wt%.

Ceramic powder is used as starting material and the production process consists of slurry {slurry} production, foaming, molding, drying and firing processes. First of all, the slurry was prepared by adding water to the ceramic powder to obtain a solid concentration of 30 to 60 vol% and sufficiently dispersed in a magnet or impeller stirrer for at least 3 hours. Second, a porous forming method was added to the slurry by adding 0.5-13 wt% of an anionic surfactant (HAITAI) to increase the temperature (80-120 ° C), followed by mixing (dispersion + concentration). I was. Changes in surfactant {surfactant} concentrations in slurry {slurry} were important factors that influenced the pore change and physical properties of porous ceramics. As the concentration of foaming slurry {slurry} increased with increasing concentration of surfactant {surfactant} as foaming agent, foaming power and stability of foam layer were improved, and the porous slurry was dried by gypsum type by fixed casting method and dried and then dried at 1150 ℃ and 1200 It was baked at 캜.

Examples 1-4

It is manufactured from ceramic raw materials in the form. Since the characteristics and size of the pore structure vary depending on each manufacturing method, a manufacturing method suitable for each application should be selected. Porous ceramics {porous ceramics} method of the polymer sponge method, the method of using the gap between the constituent particles by controlling the firing temperature, the method of using the space occupied by mixing the blowing agent or organic matter, the method using the lyophilization method, The method of foaming a slurry, and using the bubble in foam as a pore is mentioned.

In the above method, the polymer sponge method is excellent in the physical properties of the porous body mainly produced by the method of producing a network-like porous body, but it is difficult to produce a porous body of various shapes. Next, the method of using the gap between the constituent particles by controlling the firing temperature has the advantage of easily controlling the physical properties of the porous body because the size and porosity of the pores are determined according to the particle size and the filling method. There is. The method of using these spaces by mixing the blowing agent or the organic material is simple in the manufacturing process, low in specific gravity, but there is a limit in controlling the pore size. The method using lyophilization is to mold into porous fine particles, which are starting materials, and it is difficult to find pressurization conditions having a certain mechanical strength.

1. The slurry was adjusted to about 100 cps to 400 cps and used in the foaming process, and the prepared slurry had homogeneous pores of 100 μm to 500 μm in the range of 30 to 60 vol% of clay.

2. Microstructural observation of the specimen showed that as surfactant concentration increased, the pore size decreased and the distance between pores narrowed. In the optimum foaming amount of surfactant {surfactant} 6.0wt% or more, the pore size of the dried product is in the range of 200 ~ 300㎛, and the slurry of surfactant concentration of surfactant {surfactant} of 6.0wt% fired at 1150 ℃ or more When calcined at 1150 ° C., a porous ceramic sintered body having an apparent porosity of about 45%, an absorption rate of about 50%, and a volume ratio of about 0.9 was obtained.

Porous ceramics having a pore size in the range of about 100-250 μm were prepared.

3. The compressive strength of the sintered specimens at each concentration decreased with increasing surfactant {surfactant} concentration, and the compressive strength of about 70kgf / ㎠ was measured at the optimum foaming amount of 6.0wt%.

4. The physical properties of each specimen showed that all specimens were sintered as the temperature increased, so that the shrinkage and specific gravity increased, the porosity and absorption decreased, and the physical properties of the surfactant {surfactant} increased. As the surfactant {surfactant} increased, the porosity, absorption rate, shrinkage rate, etc. increased, and the specific gravity decreased. When the slurry prepared by adding more than 6.0wt% of surfactant {surfactant} powder detergent (HAITAI), which is the optimum foaming amount, was formed and calcined at 1150 ° C, the physical properties of the porous ceramic sintered body were 50% water absorption and 45% porosity. %, Shrinkage about 15%, specific gravity about 0.9.

Claims (2)

Manufacturing method of foam slurry Ceramic powder was used as starting material, and the manufacturing process was made by adding water to slurry {slurry, ceramic powder]. slip( Also referred to as}), manufacturing, foaming, molding, drying and firing processes. First, the slurry is prepared by adding water to a ceramic powder having an average particle size of 3 μm or less so that the solid concentration is 30 to 60 vol%, and sufficiently dispersed in a magnet or impeller stirrer for at least 3 hours to prepare a slurry for foaming. Porous Formation Method Mixing method (dispersion method + concentration method), which is a method of stirring while heating and heating (80-120 ° C) by adding 0.5-13 wt% of HAITAI, etc., with a powder detergent which is an anionic surfactant to the foaming slurry of claim 1 as a porous forming method. And foaming so as to have homogeneous pores having a pore size of about 100 μm-500 μm. In the porous ceramic product, the pore size of the dried product is in the range of 200 ~ 300㎛ and the pore size of the sintered body fired at more than 1150 ℃ range of about 100 ~ 250㎛.