What Is Silica?: Fumed Silica and Precipitated Silica

Many people have heard about silica and what it can do for your business. Silica is a compound used in many applications. For instance, as glassmaking or even toothpaste.

But there are two different types of silicas: precipitated and fumed. Precipitated silica has been around longer than fumed. However, both compounds have unique properties.

This blog post will compare the differences between these two types of silicas. This is so you can decide which one would be best for your application.

So, keep reading whenever you feel ready to take on the knowledge of what is silica.

What Is Silica: the Origins?

Silica is a highly abundant compound on this planet. Humans have been using silica for a very long time, as one first used it to make pottery! Silica has also been found in rocks and sandstone around the world.

Precipitated silica gets its name from how it’s produced. It occurs by precipitation of liquid silicon with sodium hydroxide or potassium hydroxide.

Fumed silicas are created through flame hydrolysis synthesis. This involves burning carbon-containing coal in a furnace containing oxygen gas at high temperatures (1100°C). The gaseous products condense onto existing precipitated silica particles, which produces fumed silicas.

You’ll be pleasantly surprised to learn more about the history of silica. It’s a very important compound in our daily lives, and you might not even know it.

The History

The silica trade can be traced back to the Roman Empire! The demand for high-quality glass increased and precipitated silica was used to make optical lenses, windows, and even eyeglasses.

Fumed silicas were not discovered until the 1930s, when a scientist named Dr. Kistler was working on ways to produce synthetic rubber.

He needed material to create a porous structure that would trap the rubber. Dr. Kistler discovered fumed silica by accident when he found out they could be produced through flame hydrolysis synthesis.

Since both precipitated and fumed silicas are made from silicon dioxide, this means their physical properties will essentially be the same with some differences in how they are processed.

Precipitated silicas can be made in larger sizes than fumed since the start particles start out bigger and then shrink during processing due to their crystalline structure.

Fumed silica is produced at a smaller particle size (around 20-40 nanometers), which makes it very reactive and gives it more surface area for chemical reactions.

What is Precipitated Silica?

Precipitated silicas are sometimes called “water glass.” They start as silicon tetrachloride (SiCl), an inorganic compound. The process begins by mixing the SiCl with sodium hydroxide or potassium hydroxide, resulting in a solid precipitate.

• Precipitated silica has numerous benefits for many applications, such as:
• Ceramics and porcelain
• Glassmaking
• Filtration processes that use filtration to prevent particles
• Textiles used on space shuttles during re-entry into Earth’s atmosphere due to its strong resistance against heat

Since it can withstand extreme temperatures, precipitated silica is used in refractory materials. For instance, insulation and furnace linings!

What is Fumed Silica?

Fumed silicas are very similar to precipitated silicones. The only real difference is that they are produced through flame hydrolysis synthesis. Fumed silicas can be added into several different types of products for various purposes, such as:

• Refrigerants
• Masking agents for spray painting since their particles scatter light instead of reflecting it
• Electronic equipment due to its ability to resist high temperatures
• Paints and coatings due to their high brightness level (i.e., giving off a white appearance) compared to other pigments
• Fumed silica is considered a specialty product since it does not have widespread uses like precipitated silicas.

With this being said, fumed silicas’ unique properties allow for many different applications. Many of which one cannot achieve with other materials!

The Differences Between Precipitated and Fumed Silicas

Precipitated silica is larger in particle size than fumed silica, which results in a higher specific surface area.

A high specific surface area allows more particles to contact the surrounding environment. It then reacts or adsorbs onto another substance.

Both types of silicone help in anti-reflective coatings because they have very low refractive indexes. However, precipitated silica requires fewer fluorine atoms when coating glass than fumed silica. Thus, making it more cost-effective.

Precipitated silicas display better hardness and abrasion resistance properties than fumed ones do. Fumes can be harmful if inhaled. Thus, many manufacturers use commercial-grade precipitated aluminas instead of fumed silicas.

Precipitated vs. Fumed Silica

Precipitated silica is a more environmentally friendly option. The manufacturing process does not produce any harmful byproducts as fumed silicas do.

• Precipitated has a larger particle size and higher specific surface area than fumed.
• Both types of silicone help with anti-reflective coatings because they have low refractive indexes
• Precipitation requires fewer fluorine atoms when coating glass than fumed
• Precipitated silicas display better hardness and abrasion resistance properties

Fumed silicas are created through flame hydrolysis synthesis. This uses a lot of energy and releases toxic gases like sulfur dioxide, hydrogen chloride, and ammonia!

Meet Your Silica Needs

So what is silica? Silica is a very versatile material that has many uses in different industries. Precipitated and fumed silicas are great options for various applications.

But it is essential to know the differences between them to choose the right one for your needs. So if you need an environmentally friendly product, precipitated silica is the better option. However, if you require something with high heat resistance, fumed silica would be better.

In either case, we can accommodate your needs. Get in touch with us now.