What is the difference between silica and fused silica?

Difference Between Silica and Fused Silica

Silica, also known as silicon dioxide (SiO₂), is a chemical compound most commonly found in nature as quartz. It is the main component of most sand and the primary ingredient in glassmaking. Silica exists in several forms, including crystalline (such as quartz), amorphous (such as opal), and hydrated forms.

Fused Silica, on the other hand, is a type of silica made from high purity silica using a fusion process. This process involves melting natural quartz crystal in a high-temperature furnace and then cooling it rapidly to produce a glassy, non-crystalline material. Fused silica has a very low coefficient of thermal expansion, excellent optical qualities, and exceptional chemical purity.

Key Differences

• Origin: Silica is naturally occurring, while fused silica is manufactured through a high-temperature fusion process.
• Structure: Silica can exist in crystalline or amorphous forms, whereas fused silica is amorphous and non-crystalline.
• Thermal Expansion: Fused silica has a significantly lower coefficient of thermal expansion compared to most types of silica, making it more stable under temperature changes.
• Optical Properties: Fused silica offers superior optical clarity and light transmission, especially in the ultraviolet (UV) range, compared to regular silica.
• Purity: The process of making fused silica results in a material with very high purity, free from inclusions and contaminants that are often found in natural silica.

These differences make fused silica particularly valuable in high-technology applications, including optics, semiconductors, and telecommunications, where its unique properties are essential.