The precipitation method is also a commonly used method in the extraction method of zirconia ceramic raw materials. The following Pintejin Ceramics Factory will take you to understand the precipitation method.
The precipitation method is a method of adding alkaline substances such as ammonia water to the mixed aqueous solution of water-soluble salts such as carboxyl zirconium chloride and stabilizer salts to obtain the co-precipitation of their hydroxides. After drying the coprecipitate, colloidal amorphous is generally obtained, which is calcined at about 500~700℃ to make ZrO2 powder. This method can prepare powder with fine particle size, good chemical uniformity and easy sintering.
Zirconia ceramic rod In the general co-precipitation method, the excess precipitant is precipitated with all the cations in the solution at the same time, avoiding the loss of effective cations. The preparation of ZrO2 powder by co-precipitation method has become increasingly mature, and many ZrO2 ceramic powders can be prepared by co-precipitation process, such as (ZrO2/Al2O3, ZrO2/MgO, ZrO2/CeO, ZrO2/Y2O in the process of preparing ZrO)2 powder by co-precipitation method The pH value, precipitation treatment process, combustion temperature and drying process are the main factors affecting precipitation and powder properties.
The study found that the gel washed with water produced hard agglomeration, which could not be broken during ball milling, while the gel washed with alcohol produced soft agglomeration or no agglomeration. influences.
In order to reduce or eliminate agglomeration, it is necessary to add organic macromolecular surfactants during the precipitation process and when the sediment source is eluted with water, such as polyacrylate ammonium, polyethylene glycol, etc., which can be reduced by the steric hindrance effect of organic macromolecules. The degree of agglomeration improves the properties of the powder. The surfactants are mostly selected with different charges on the particle surface and the same charge as the impurity particles to be removed.
Ceramic tube One end of the polymer surfactant is tightly adsorbed on the particle surface, and the other end extends into the solution as much as possible to form steric hindrance and reduce agglomeration.
The amount of surfactant should be appropriate. If the surface adsorption of the particles is insufficient, the other end will be adsorbed and aggregated with other particles in the drying stage. There is a gas-liquid interface in the capillary pores in the powder, and the particles will be pulled each other by the action of surface tension. If the gas-liquid interface with huge surface tension is eliminated, or the particles are fixed and cannot approach each other, hard agglomeration will not be caused. According to this basic idea, supercritical drying, freeze drying and spray drying have been developed to prepare zirconia powder in recent years.
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