Fused quartz grades

What type of vitreous silica is needed for an application depends on the individual requirement. The fused quartz grades Heraeus offers are grouped by:

Each group contains the individual material grades. These are diffentiated mainly by chemical purity. For a quick review of the individual fused quartz glass type and some example of typical applications, have a look at the table.

Electrically fused quartz glass
Electric fusion is the most commonly used melting process for producing quartz glass. The two methods used are the continuous vertical drawing (V-Zug) and batch fusion (for details see technology competence). Electric fused silica is the first choice for applications in high temperatures due to extremely low hydroxyl (OH) content. The lower the OH-content, the higher the temperatures at which the glass softens.

Flame fused quartz glass
Fusion of quartz glass in the hydrogen/oxygen flame (Verneuille-Prozess) is the most traditional production process of fused quartz glass. A characteristic property of flame fused quartz glass is the low amount of bubbles within the material. The relatively high OH content qualifies the material as a diffusion barrier in doping processes.

Synthetic quartz glass
Making quartz glass from synthetic precursors leads to the highest feasible purity and homogeneity. This material is qualified for applications with optical or high purity requirements.

Opaque quartz glass
Opaque fused quartz is used for its excellent heat blocking properties. Heraeus offers material produced in a ceramic process as well as arc melted material. The first is unique to Heraeus and has the best reflectance on the market (OM 100), the later material is ideal for large bodies in rotational symmetry (OFM).