What factors are related to the surface modification effect of ultrafine powder?
Powder surface modification is mainly to reduce the energy of ultra-fine powder to achieve uniform dispersion. The effect of powder surface modification depends on powder processing technology, back-end product processing technology and system compatibility, material formulation, etc. Factors are related.
- The nature of powder raw materials
The specific surface area, particle size, particle size distribution, specific surface energy, surface physical and chemical properties, and agglomeration of the powder raw materials all have an impact on the modification effect, which is one of the important factors in the selection of powder modifier formulations, process methods and equipment.
For example, the physical and chemical properties of the surface of the powder, such as surface electrical properties, wettability, functional groups or groups, dissolution or hydrolysis characteristics, directly affect its interaction with the powder modifier molecules, thereby affecting the effect of its surface modification . At the same time, the physical and chemical properties of the surface are also one of the important factors in choosing the surface modification process.
- Powder modifier formula
The surface modification of the powder is to a large extent achieved by the action of the powder modifier on the surface of the powder. Therefore, the formula (variety, dosage and usage) of the powder modifier has an important influence on the modification effect of the powder surface and the application performance of the modified product. The powder modifier formula is very specific, that is, it has the characteristics of “a key to open a lock”. The formula of powder modifier includes selection of varieties, determination of dosage and usage, etc.
When selecting a powder modifier, the properties of the powder raw materials, the use or application field of the product, as well as factors such as process, price and environmental protection should be considered comprehensively, and according to the structure and properties of the powder modifier and its relationship with the powder Mechanism of action, targeted selection.
- Superfine surface modification process
After the powder modifier formula is determined, the surface modification process is one of the important factors affecting the surface modification effect. The surface modification process should meet the application requirements or application conditions of the powder modifier, have good dispersibility to the powder modifier, and be able to achieve uniform and firm coating of the powder modifier on the powder surface; at the same time, the process is required Simple, good parameter controllability, stable product quality, low energy consumption and low pollution.
Therefore, at least the following factors should be considered when choosing a surface modification process:
①The characteristics of the powder modifier, such as water solubility, hydrolysis, boiling point or decomposition temperature, etc.;
②Whether the front-stage crushing or powder preparation process is wet or dry? If it is a wet pulverization process, a wet modification process can be considered;
③Surface modification method. The method determines the process. For example, for surface chemical coating, either dry or wet process can be used; but for precipitation coating of inorganic powder modifier, only wet process can be used.
At present, the commonly used surface modification processes mainly include dry process, wet process, pulverization and surface modification combined into one process, drying and powder modifier use methods combined into one process, etc.