Micro silica powder in purity, density, particle size of different can be divided into different types, different types of micro silica fume and its performance, price, uses are not the same. Specifically as follows:
(a) by SiO2 content.
1, SiO2 = 85%, the typical value of more than 88%, mainly to control the ignition loss (less than 6%), for concrete and low-grade refractory.
2, SiO2 = 90%, the typical value of about 92%, according to customer requirements for control related impurities, and general refractory concrete.
3, SiO2 = 92%, the typical value of about 94%, there are specific requirements, requirements for high-grade refractory to liquidity.
4, SiO2 is greater than or equal to 97%, the typical value is above 96%, there are strict impurities and pH value, but different customer focus inconsistent, used for high-grade refractory.
(two) by density
1, the original state, the 100-170kg/m3 is easy to bond, transport properties.
2, mild encryption, 250-400kg/m3, the basic no particles, transport significantly improved. But the temperature is not stable.
3, semi encryption 400-500kg/m3, began to appear a large number of loose particles, not easy to bond, better transport.
4, high density 500-700kg/m3, the basic to the hard particles (different particle size and close degree of different products), transport.
(three) by the size of the particle size or specific surface area
1, median diameter around 0.3um, specific surface area in 15-25m2/g. Almost all of the particles particle diameter is equal to or less than 1um, in the world the vast majority of silica fume belong to such values.
2, in a size or below 0.1um or so, specific surface area value was more than or equal to 30m2/g, generally appear in high purity silica powder, are relatively rare.
3, median diameter in 0.5-2.0um, specific surface area in 5-15m2/g, rare.
4, the median diameter of more than 2.0um, very rare, poor service performance.
To sum up, the user should according to the actual need to select the appropriate type of micro silica fume, that is economical and can achieve the best effect.
