What is a Conductive Ceramics material?
Conductive Ceramics materials are a kind of important ceramic materials, which are widely used in many fields because of their unique three-dimensional porous structure, which has high porosity, good chemical stability, small bulk density and low thermal conductivity.
Conductive Ceramicss due to the uniform distribution of micropores and pores, high porosity, small bulk density, but also has a developed surface, ceramic materials unique high temperature, corrosion resistance, high chemical and dimensional stability, so that porous materials can Gas liquid filtration, purification separation, chemical catalytic carrier, sound absorption shock, insulation materials, biological materials, special wall materials and sensor materials and other aspects of a wide range of applications.
Preparation of Conductive Ceramics materials
1 Extrusion method
Extrusion is a plastic deformation process, can be divided into hot extrusion and cold extrusion. Usually in the press to complete, so that the workpiece plastic deformation, to achieve the desired shape of a process. The process is to produce a good mud through a pre-designed with a honeycomb grid structure of the mold extrusion, after sintering can be a typical Conductive Ceramics.
It is now used for automobile exhaust gas purification of honeycomb ceramics, which is prepared by a good mud through a pre-designed with a honeycomb grid structure of the mold extrusion, after sintering to get a typical Conductive Ceramics.
The advantage of this process is that the shape and size of the hole can be precisely designed according to the actual needs; the disadvantage is that it can not form a complex pore structure and pore size of the material, while the plastic extrusion materials have higher requirements.
2 particles deposited into the hole method
Particle accumulation process is to add the same components in the aggregate of fine particles, the use of fine particles easy to sinter the characteristics of liquefaction at high temperatures, so that the aggregate together.
The larger the aggregate size, the larger the average pore size of the Conductive Ceramics and the linear relationship. The more uniform the particle size of the aggregate, the more uniform the distribution of the pores, and the smaller the pore size distribution.
In addition, the content and type of additives, as well as the firing temperature of the microporous body distribution and pore size is also directly related. The main advantage of this process is that the process is simple and the preparation strength is high. The disadvantage is that the porosity is low.
3 Add the pore forming method
The process is through the ceramic ingredients in the addition of pore-forming agent, the use of these pore-forming agent in the body to occupy a certain space, high temperature burned or evaporated in the ceramic body after leaving the pores. The use of this process can be prepared complex shape, pore structure of Conductive Ceramics products.
The process is compared with ordinary ceramics, the key lies in the types and selection of pore-forming agent, followed by the size of the size. The pore-forming agent can be divided into organic and inorganic.
The advantages of adding the pore-forming agent process are:
The size of the porosity and the shape of the pores can be adjusted; the process is simple;
The downside is that:
Poor uniformity of stomatal distribution, not suitable for the preparation of high porosity products.
4 foaming process
The foaming process is the addition of organic or inorganic chemicals to the ceramic component to form a volatile gas during the heat treatment to produce foam ceramics of various pore sizes and shapes which can be made by drying and sintering the mesh and Foam type two kinds of Conductive Ceramicss.
Foam process is easier to control the shape, composition and density of the product, and is particularly suitable for the production of closed-cell ceramic products.
5 sol - gel process
Sol-gel method can be used to prepare nano-sized microConductive Ceramicss, which is the use of gelation process of colloidal particles accumulation and gel treatment, heat treatment process leaving small pores, the formation of controllable porous materials.
The basic process is to dissolve the metal alkoxide in the lower alcohols, slowly dropping water into the hydrolysis reaction to obtain the corresponding metal oxide sol, adjust the pH of the sol, nano-scale metal oxide particles will produce aggregation. The sol-gel method is mainly used to prepare microConductive Ceramics materials, especially microConductive Ceramics films.
Freeze drying technology
Freeze drying technology can be used to prepare Conductive Ceramics with complex pore structure.
When the ceramic slurry is frozen and solidified, the growth direction of crystal ice is controlled at the same time.
In the low pressure conditions for drying, then ice sublimation directly into a gas;
And the resulting green body is sintered.
Thereby obtaining Conductive Ceramicss having an internal hole orientation arrangement. The structure of the pores can be controlled by controlling the starting slurry concentration and the sintering time.
As the process of forming the process does not use organic pore-forming agent, does not produce pollution, with environmental friendliness, in today's sustainable economic environment has a good application prospects.
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