Classification & Action Mechanism of Ceramic Additives
With the progress and improvement of the process, various chemical additives play an increasingly important role in the production of ceramics.
It's role is mainly reflected in two aspects: one is as a process additive, such as improving processing conditions and simplifying the process; the other is as a functional additive, such as adding to the product to have some specific functions.
Classification of Ceramic Additives:
There are many types of ceramic additives, which can be divided into the following categories according to their compound composition, function, state and application fields:
(1) According to its chemical composition, it can be divided into organic, inorganic, polymer and composite additives;
(2) According to their functions, they can be divided into debonders, plasticizers, reinforcing agents, grinding aids, defoaming agents, flocculants, preservatives, etc.;
(3) According to its state, it can be divided into two categories: solid additives and liquid additives;
(4) According to its application field, it can be divided into ordinary ceramic additives and new ceramic additives.
The action mechanism of ceramic additives:
① Dispersion.
The system formed by the dispersion of solid particles in a liquid medium should belong to the category of colloid, which is thermodynamically unstable and the particles tend to agglomerate.
At this time, the addition of ceramic additives can prevent the mutual agglomeration of the ceramic particles by interacting with the surface of the ceramic particles, which can prevent the particles from agglomerating, so that the components of the raw materials are uniformly dispersed in the liquid medium.
The dispersion mechanism of ceramic addition is roughly divided into four types: electrostatic repulsion stabilization; steric hindrance stabilization; electrostatic steric hindrance and stabilization.
② Suspension.
Some solid particles that are insoluble in water or slightly soluble in water can be dispersed evenly in the liquid medium with the help of certain ceramic additives to form a small, highly suspended, flowing stable liquid-solid system, which can improve the suspension of the slurry and effect of stability.
The mechanism of suspension stabilization is actually similar to that of dispersion. In fact, various suspension stabilizers can also be used as dispersants for ceramic slurry, but the dispersants are mainly used in the slurry, while the suspension stabilizer is mainly used in the glaze slurry. It has a thickening effect on glaze slurry and is an additive to prevent glaze slurry precipitation.
③ Water Reducing Effect.
The water reducing effect of ceramic additives is to improve the performance of the slurry, so that the slurry has appropriate viscosity, good fluidity and high solid content in the case of low moisture, so as to facilitate operation and achieve the purpose of energy saving and consumption reduction.
The dispersion mechanism of ceramic water reducer is roughly divided into four types: electrostatic repulsion stabilization; steric hindrance stabilization; electrostatic steric hindrance and stabilization. The system formed by the dispersion of clay particles in a liquid medium is a colloid. The system is thermodynamically unstable. The particles will attract each other and then agglomerate. The ceramic additive acts on the surface of the ceramic particles to prevent them from agglomerating. Play the role of preventing particle agglomeration.
④ Enhancement.
In the process of ceramic production, for some kaolin with poor texture, it is often necessary to add some ceramic additives to make up for its poor plasticity or improve the strength of the initial product.
The principle of action of the ceramic reinforcing agent is that it can bridge between the ceramic particles, produce cross-linking effect, and form an irregular network structure; at the same time, the surface of the particles is wrapped and hydrogen bonds are generated between the particles, which greatly enhances the strength of the product.
⑤ Grinding Aid.
The grinding aid of ceramic additives is mainly to improve the grinding efficiency of ceramic powders and accelerate the crushing speed of solid particles from the microscopic mechanism of raw material grinding. The ceramic additive with grinding aid is called grinding aid.
