Silica glass is a single component of silica glass, usually divided into transparent quartz glass and opaque quartz glass (fused silica) two categories. Transparent quartz glass only a very small amount of air bubbles, very high optical uniformity and transparency, by the crystal or silicon tetrachloride as raw material, by high temperature melting, SiO2 content in more than 99.95%, high purity quartz glass called 99.999%, opaque quartz glass is quartz, quartz sand as raw material, by high temperature melting, containing more than SiO299.5%.
The quartz glass is by simple (SiO4 tetrahedra. Net framework, and silicon oxygen bond strength large, compact structure, so mechanical strength and heat resistance is very high, thermal expansion coefficient is very small, chemical stability is also very good. At the same time, viscosity, softening point is also very high, due to the network without interstitial cations, so small density, conductivity, dielectric loss is also very small.
Mechanical properties of the quartz glass is better than hard glass and ceramics, pull the new defect free quartz glass fiber strength is 24100 x 106 PA, small diameter quartz tube and quartz glass equipment can endure great pressure, quartz glass products if macroscopic defects, such as bubbles, external miscellaneous material, melting inhomogeneity and the presence of residual stress will affect their strength, to reduce.
Strength of quartz glass began to increase with the temperature, to a certain temperature, but with the temperature increase and decrease, transparent quartz glass from the room temperature increased to 900oc, tensile strength increased by about one times, anti impact strength showed maximum value.