Silica powder is a kind of silica powder material, which is made of natural quartz ore and fused quartz and processed by many processes such as grinding, precision classification and impurity removal. Grinding is one of the core processes in the production of silica powder, which directly affects its purity, particle size distribution and production cost.
In order to produce silicon powder with stable quality and high performance, management and control must be strengthened from the following aspects:
1. Mill control
It can effectively control the impurity content and improve the service life of the equipment by reasonably selecting the grinding medium material, controlling the medium ratio and filling rate; reasonably adjust the rotation speed of the ball mill according to the length diameter ratio of the ball mill, the structure and distribution of the lining plate, the grinding particle size, etc., so as to maintain the good movement state of the materials in the grinding chamber, so as to improve the grinding effect.
2. Particle shaping
By optimizing the operation speed of the equipment, the pressure and temperature in the body and the residence time of the material, the regularity of the surface of the silica fume can be improved, the fluidity of the product can be improved, and the high filling and dispersion of the silica fume in the downstream resin system can be facilitated.
3. Mixed compounding
The single peak distribution of silicon powder can not achieve the most compact stacking, it is difficult to meet the high filling requirements of customers, and can not maximize the excellent performance of silicon powder. One of the ways to improve the filling rate is to mix the silicon powder products with different particle size distribution to form a multi peak distribution through the proportion mixing, so as to achieve high filling and reduce the oil absorption value of the silicon powder.
4. Surface modification
As an inorganic filler, silicon powder has poor compatibility and dispersion when mixed with organic resin, which leads to poor heat resistance and moisture resistance of materials such as integrated circuit packaging and substrate, thus affecting the reliability and stability of products. In order to improve the interface combination of silicon powder and organic polymer materials and improve their application performance, the surface modification of silicon powder is generally required.
5. Production condition control
The key to the production of electronic grade silicon powder is to remove the conductive impurities in quartz. Therefore, in addition to the selection of pure raw materials, the pollution of containers, environment, chemicals and other products should be minimized and strictly operated in every link of production.
For example, in order to avoid material pollution during grinding, the grinding medium used should be non-metallic materials such as alumina ceramic ball or silica; the barrel of the mill must also be lined with high-strength wear-resistant materials such as alumina ceramic, silica or polyurethane rubber.
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