Micro Silica Fume

Silica fume-also known as silica fume-also known as micro silica fume or ultrafine silica powder-generally referred to as silica fume.

Silica fume is an ultra-fine siliceous powder material formed by the rapid oxidation and condensation of SiO2 and Si gas produced during the smelting of ferrosilicon alloy and industrial silicon and oxygen in the air.

1. Silica fume: the appearance is gray or off-white powder, and the refractoriness is >1600℃. Bulk density: 200～250 kg/m3

2. The fineness of silica fume: its fineness and specific surface area are about 80-100 times that of cement and 50-70 times that of fly ash.

3. Particle morphology and mineral phase structure: during the formation process of silica fume, due to the effect of surface tension in the process of phase transformation, amorphous spherical particles of amorphous phase are formed, and the surface is relatively smooth, and some have multiple circles. Agglomerates of spherical particles sticking together. It is a kind of volcanic ash material with large specific surface area and high activity. For materials mixed with silica fume, tiny spheres can play a lubricating effect.

To Silica fume can fill the pores between cement particles, and at the same time form a gel with the hydration product, and react with the alkaline material magnesium oxide to form a gel. In cement-based concrete, mortar and refractory castables, mixing a proper amount of silica fume can play the following roles:

1. Significantly improve the compressive, flexural, impermeable, anti-corrosion, impact and wear resistance properties.

2. It has the functions of retaining water, preventing segregation and bleeding, and greatly reducing the resistance of concrete pumping.

3. Significantly prolong the service life of concrete. Especially in harsh environments such as chloride pollution erosion, sulfate erosion, and high humidity, the durability of concrete can be doubled or even several times higher.

4. Significantly reduce the landing dust of sprayed concrete and castables, and increase the thickness of single sprayed layer.

5. It is a necessary component of high-strength concrete, and C150 concrete has been used in engineering.

6. It has about 5 times the effect of cement, and can be used in ordinary concrete and low cement castables to reduce costs and improve durability.

7. Effectively prevent the occurrence of concrete alkali aggregate reaction.

8. Improve the compactness of castable refractories. When coexisting with Al2O3, it is easier to form mullite phase, which increases its high-temperature strength and thermal shock resistance.

Application areas of silica fume

1. Used in mortar and concrete: 

High-rise buildings, seaports, reservoirs, dams, water conservancy, culvert gates, railways, highways, bridges, subways, tunnels, airport runways, concrete pavements and coal mine tunnels, etc.

2. In the material industry:

(1) High-grade, high-performance, low-cement refractory castables and preforms have a service life that is three times that of ordinary castables. The refractoriness is increased by about 100°C, and the high-temperature strength and thermal shock resistance are significantly improved. Has been widely used in: coke oven, ironmaking, steelmaking, steel rolling, non-ferrous metals, glass, ceramics and power generation industries.

(2) Large iron trenches and ladle materials, air-permeable bricks, smear repair materials, etc.

(3) Application of self-flowing refractory casting materials and dry and wet spraying construction.

(4) Oxide-bonded silicon carbide products (ceramic kiln furniture, flame screens, etc.).

(5) High-temperature calcium silicate light-weight insulation material.

(6) Corundum and mullite push plates for electric porcelain kilns.

(7) High-temperature wear-resistant materials and products.

(8) Corundum and ceramic products.

(9) Sialon combined products.

In addition to being widely used in castable refractories, it has also been widely used in fused and sintered refractories.

3. New wall materials and facing materials:

(1) Polymer mortar, thermal insulation mortar and interface agent for wall insulation.

(2) Cement-based polymer waterproof material.

(3) Lightweight aggregate thermal insulation and energy-saving concrete and products.

(4) Putty powder processing for interior and exterior wall construction.

4. Other uses:

(1) Raw materials of silicate bricks.

(2) Production of water glass.

(3) Used as a reinforcing material for organic compounds. Because its composition is similar to white carbon black produced by gas phase method. It can be used as a filling and reinforcing material in polymer materials such as rubber, resin, paint, paint, unsaturated polyester.

(4) Used as an anti-caking agent in the fertilizer industry.