QUARTZ, FUSED QUARTZ, FUSED SILICA, WHAT’S THE DIFFERENCE?
Quartz is a term used to describe many different compact forms of SiO2. As one of the second most common and varied minerals on earth, its abundant and can be found in crystalline form, naturally occurring, in many colors that produce different types of gemstones.
What is Fused Quartz/Fused Silica?
Fused quartz and fused silica is glass consisting of fused silica in an amorphous solid, it has a non-crystalline form. It has very little impurities compared to other forms of glass that have materials added which lower the working temperature. Thus, absent the added impurities, fused quartz and fused silica have very high working temperatures and are able to be used in many applications such as semiconductor fabrication and laboratory equipment.
The difference between fused quartz and fused silica:
Fused quartz starts with high purity quartz, or other SiO2 containing minerals that are fused using various heat sources. Any of the resulting products manufactured using this method are referred to as fused quartz. There are two methods for producing fused quartz: electric fusion and flame fusion. The electric fusion is the most commonly used melting process for manufacturing fused quartz glass. We use fused quartz as it has a very low OH (hydroxl) content which helps retard devitrification. One example of fused quartz is GE 124.
Fused silica starts with a vapor cloud containing silicon chemicals that when burned with oxygen produces SiO2. The nano-particles of SiO2 are referred to as ‘soot’. Because the chemicals are specifically produced and refined, they are available in exceptionally high purity and the resulting fused silica has a very low metallic impurity content, but can have a higher OH content as a result. The process by which fused silica is produced is called chemical vapor deposition (CVD). One example of fused silica would be Corning® 7980.