Fumed Silica
Name:
Fumed silica
Appearance:
Fluffy white powder.
Technical Data of Fumed Silica
|
Item |
Indexes |
|
The nitrogen adsorption specific surface area/（m2/g） |
Typical values±30 |
|
Loss on ignition/% ≤ |
|
|
Silica content/% ≥ |
|
|
Suspension PH |
|
|
Al2O3 content/（mg/kg） ≤ |
400 |
|
TiO2 content/（mg/kg） ≤ |
200 |
|
Ti2O3 content/（mg/kg） ≤ |
30 |
|
Carbon content/% ≤ |
|
|
Chloride content（mg/kg） ≤ |
250 |
|
105℃ volatiles/% ≤ |
3 |
|
Tap density /（g/dm3） |
30~60 |
|
45μm screenings/（mg/kg） ≤ |
250 |
Applications of Fumed Silica
Due to its small particle size, the specific surface area is big, therefore the surface adsorption power, surface energy, high chemical purity
Package Storage and Transportation
This product's hygroscopicity is strong, with more than three layers of kraft paper valve bag packaging, using vacuum packaging machines, automatic packaging.
Description of Fumed Silica
Fumed silica, molecular formula is SiO2. White fluffy powder, porous, non-toxic, tasteless and pollution-free, high-temperature resistant. At the same time, it has the chemical inertness and special thixotropy can significantly improve the tensile strength, tear-resistance, and wear resistance of rubber products, rubber improved strength increased by tens of times. It can be used as rheological and thixotropic control for liquid systems, adhesives, polymers, etc., as an anti-sink, thickening, anti-sagging additive, reinforcement for HCR and RTV-2K silicone rubber, used to regulate free flow, and as an anti-caking agent to improve powder properties, etc. ZHONGTIAN EAST FLUORINE SILICON MATERIAL CO.,LTD. provides fumed silica for sale. As fumed silica manufacturers, we can offer a reasonable fumed silica price. Customers can buy fumed silicafor their different needs.
The Role of Fumed Silica in Coatings
Rheology additives
Rheology is an important property of coatings, which directly affects the appearance, construction performance and storage stability of coatings, and the requirements of rheology additives vary from coating system to coating system. For oil-based systems, most of the rheology additives work by forming hydrogen bonds. The untreated fumed silica aggregates on the surface contain multiple, one of which is isolated and undisturbed free, and the other is continuous, forming hydrogen bonds with each other. When the shear force is removed, the three-dimensional structure will recover itself and the viscosity will rise. In completely non-polar liquids, the viscosity recovery time is only a fraction of a second; in polar liquids, the recovery time is longer, depending on the concentration of fumed silica and its degree of dispersion, this characteristic gives oil-based coatings very good storage and construction performance, especially thick paste-shaped coatings, both to ensure that the coating in a certain construction shear has good fluidity, but also to ensure that the coating film of a construction thickness, usually, In the construction process, because the solvent at the edge of the coating evaporates faster, resulting in uneven surface tension, easy to make the coating move to the edge, and the silica network can effectively prevent the movement of the coating and form a thick edge, but also to prevent the coating in the curing process of the hanging phenomenon, so that the coating uniform. At the same time, fumed silica can form hydrogen bonds and increase the low and medium shear viscosity in the system, thus playing a thickening role. Therefore, fumed silica is very widely used in oil-based systems.
Fumed Silica Powderin Foods
Silicon dioxide, a non-metallic oxide formed from silicon and oxygen, can be divided into two main groups; crystalline and amorphous silica. Crystalline silica may exist in several different forms, including quartz, square quartz, and tridymite. Amorphous silica mainly includes hydrolytic silica and fumed silica. The conventional form of amorphous silica is known as a food additive, and fumed silica powder has been used for many years as an important component in food applications such as sauces and seasoning powders, instant noodles, pancake and cake mixes, coffee creamers and vitamins.
For decades, fumed silica powder has had a wide range of applications in the food industry as an anti-caking agent in powdered mixtures, flavorings and coffee whitening agents. Fumed silica powder is a widely used anti-caking agent in the pharmaceutical and food industries. Fumed silica is hydrophilic and has a large number of hydroxyl groups on its surface, which readily interact with each other through hydrogen bonding to form a three-dimensional network. Hygroscopic fumed silica works by absorbing moisture from the environment without liquefying it, reducing friction between particles. In addition, fumed silica is used as a viscosity control agent, emulsion stabilizer, suspending and dispersing agent, desiccant, etc.
Unique "Three-Dimensional Dendritic" Structure of Fumed Silica Powder
As fumed silica powder in the production process, the first halosilane hydrolysis condensation into a single silica particles, and then gradually grow into 7-40 nanometers spherical particles, the particles are called "primary particles" (Primary Particle) of silica.
The "primary particle" in the reaction furnace with the direction of the flame continues to move forward, the particles collide with each other, at this time, because the temperature in the reaction furnace is still relatively high, the particles are still close to the molten state, the particles collide and fuse together, forming a three-dimensional dendritic structure of multiple spherical particles fused together, known as the silica "Aggregate Particle". Since the particles in the aggregates are fused together, they are stable structures that are almost impossible to separate.
Aggregate particles of silica continue to move forward and collide with each other in the pipe, and then join together to form a flocculent, fluffy powder called an Agglomerate Particle of silica. . Due to the low temperature in the pipe, the connection between the "aggregates" is only connected by physical adsorption, which is an unstable structure and can be separated under certain mechanical force.
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