What is the Difference Between Fumed Silica and Silica Fume

The benefits of fumed silica and silica fume in the manufacturing and construction industries are well known. While the two terms seem similar, the products have apparent differences. Unfortunately, most people use the terms interchangeably. Here is everything you need to know about fumed silica and silica fume. Fumed silica or pyrogenic silica is a multi-purpose silica-based additive commonly used to manipulate viscosity and rheology and enhance the functionality of existing polymer matrices. It has a low particle size and bulk density, meaning the surface area is very high. It is known for its film and cured adhesives strengthening, sag resistance, and anti-settling properties. When silicon tetrachloride is heated in an aerobic environment at temperatures above 1500°, silicon dioxide is formed. With increasing heat and pressure, this silicon dioxide combines with itself, forming aggregates and fumed silica agglomerates. The three-dimensional structure of fumed silica increases viscosity. Fumed silica also exhibits a thixotropic behavior, mainly as a reinforcing filler or thickener. It is typically classified into treated and untreated categories (hydrophilic and hydrophobic). Generally, hydrophobic fumed silica is cheaper than hydrophilic. Fumed silica commonly exhibits a particle size of around 5-50 nm, a bulk density of 160 – 190 kg /m2, and a surface area of 50 – 600 m2/g. Silica fume is another silica-based additive used in cementitious applications. It is classified as ultrafine, with the size of spherical particles being less than 1 µm in diameter, 100 – 150 times smaller than an average cement particle. It acts as a pozzolan and filler when used in cementitious applications like concrete, repair products, and shotcrete. A pozzolan is a siliceous material with little or no cementitious composition. If you are looking for high quality, high purity, and cost-effective Fumed Silica, or if you require the latest price of Fumed Silica, please feel free to email contact mis-asia.