the classification of micro silica

Micro silica powder (silica fume) can be divided into different types according to the purity, density and particle size distribution. The micro silica is different types as well as in properties and usages. More details as follows:

1.According to the SiO2 content
◆SiO2≥85%, typical values 88% above, the main control ignition loss (6%), it is used in concrete and low-grade refractory material.
◆SiO2≥90%, typical values about 92%, according to customer require control related impurities, it is used in general refractory material and concrete.
◆SiO2≥92%, typical values about 94%, there are specific requirements, the liquidity requirements for high-grade refractory material.
◆SiO2≥97%, typical values 96% above, there will be strict impurity and PH requirements, but different customers have different focus, it is used in high-grade refractory materials.

2.According to the density
★Original state, 100-170kg/m3, it is easy to bond and poor delivery.
★Mild encryption, 250-400kg/m3, few particles, delivery is improved significantly. But it is instability by the temperature affected.
★Half the encryption, 400-500kg/m3, begin to appear a large number of granular, it is not easy to bond as well as good delivery.
★High density 500-700kg/m3, it is based on the hard particles (different product particle size and tightness). Delivery is excellent.

3.According to particle size or specific surface area
►The median diameter at about 0.3 um, surface area values in 15-25m2/g, all of the particle size≤1um, the majority of micro silica powder is like this in the world.
►The median diameter at about 0.1 or below, surface area values in more than 30m2/g, it generally appears in high purity micro silica powder.
►The median diameter at about 0.5-2.0um, surface area values in 5-15m2/g; rare.
►The median diameter more than 2.0um, very rare, poor using performance.