What factors are related to the surface modification effect of ultra-fine powder?
The surface modification of powder is mainly to reduce the energy of ultrafine powder through the powder modifier to achieve the effect of uniform dispersion. The effect of the surface modification of the powder is related to the powder processing technology, the processing technology of the back-end products，the system compatibility，material formula and others.
1. 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, and are important factors for selecting powder modifier formulations, process methods and equipment. one.
For example, the surface physical and chemical properties 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 considerations when choosing a surface modification process.
2. 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 highly targeted, that is, it has the characteristics of “a key to open a lock”. The formula of the 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 based on the structure and properties of the powder modifier and its relationship with the powder. Mechanism of action, targeted selection.
3. Ultra-fine surface modification process
After the powder modifier formula is determined, the surface modification process is one of the most important factors that determine 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 realize the 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 grinding or powder preparation operation is wet or dry. If it is a wet process, consider adopting a wet modification process;
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.