In the special piezo ceramicindustry, there are also some "flavoring agents". Although the amount added in the piezo ceramic formula is very small, it has a very important role in improving the processing performance of special piezo ceramics and improving the performance of special ceramic products. In the field of special ceramics, the types of "flavoring agents" are increasing day by day, and they play an irreplaceable role in improving the refinement and functionalization of ceramic production. These "flavoring agents" in the piezo ceramics industry are called ceramic additives.
Types of "flavoring agents" in special piezo ceramics formulas
In pzt ceramic formulations, commonly used "flavoring agents" include dispersants, binders, plasticizers, flocculants, mineralizers, defoamers, lubricants, etc. The specific uses and types are shown in the following table.
Introduction of several typical "flavoring agents"
Dispersant
In the pzt ceramic system, the pzt powder particles are suspended in the solvent medium and have a tendency to agglomerate and precipitate. The role of the dispersant is to hinder this phenomenon of aggregation, so that the particles can be evenly dispersed and suspended steadily. Its dispersion mechanism is mainly "electrostatic repulsion" and "steric hindrance" effect.
Sodium silicate is commonly known as "water glass", and its liquid form is translucent or slightly transparent and viscous, and can be dissolved in the water; when it encounters acid, it will precipitate colloidal precipitate. Sodium silicate is a kind of PH regulator and particle suspending agent, which can maintain a moderate pH value of the dispersion and can effectively suspend the particles. Fatty alcohol polyoxyethylene ether is a representative product of non-ionic dispersant, with large output, many varieties and wide application. Using fatty alcohols of different specifications and adding different amounts of ethylene oxide can obtain products with different properties. Generally speaking, as the hydrophobic chain increases, the dispersibility of the product increases. Among them, products with 6-12 mol of ethylene oxide mixed with C12-C16 alkane chain have the best dispersion effect.
Adhesive
The binder binds the powder together by intermolecular force.Polyvinyl alcohol (PVA) is white or slightly yellow in appearance, non-toxic; melting point 228 ℃, relative density 1.31 ～ 1.34; under the normal circumstances, its viscosity index is directly proportional to the degree of polymerization, with better adhesion and flexibility wear resistance. Carboxymethylcellulose (CMC) is widely used. Medium and low polymerization products are commonly used, with strong solubility and low viscosity. It is generally used in the preparation of glaze slurry.
Plasticizer
Plasticizers mainly play the role of plasticizing by lubricating or reducing the intermolecular force.Phthalates are the most widely used plasticizers, generally used as the main plasticizers, and are known as universal plasticizers. Among them, dihexyl phthalate is the variety with the largest output and the best comprehensive performance among such plasticizers. It embodies the most ideal combination of cost, practicality and processing performance of piezo ceramic ring, and is regarded as the standard of general plasticizers.
The main function of the flocculant of low frequency piezoelectric block is to neutralize the surface charge of the colloidal particles and reduce the zeta potential of the colloidal particles. If the zeta potential tends to or equal to zero, the flocculation effect is the best.
Aluminum sulfate is generally 18 crystalline water compounds, in the form of colorless or white lumps, granules, flaky crystals, the aqueous solution is acidic. Aluminum ions can attract and neutralize the negatively charged colloidal particles, eliminating the electrostatic repulsion between the colloidal particles, thereby causing the particles to flocculate and precipitate. Aluminum sulfate addition is cheap, easy to use, and has high cohesion. However, its PH application range is relatively narrow, ranging from 5.7 to 7.8.
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