Abstract
A new fabrication method involving pulsed electric current heating was used to investigate shortening the time and lowering the cost of fabrication of silica glass. The advantages of this technique on the functionality of silica glass are also discussed. Silica powder was filled in a graphite mold having a diameter of 20mm. The temperature on the external mold surface was raised from 1773 to 1873K at heating rates of 50 and 100K/min under a constant uniaxial pressure of 20MPa. As a result, transparent silica glass free of bubbles was successfully fabricated at the heating rate of 50K/min. However, in the case of 100K/min, crystalline particles were formed on the bulk surface in addition to numerous bubbles. These crystals are attributed to a high temperature gradient, so that the heating at the bulk surface is insufficient and the temperature does not reach the melting point of silica. Investigation of the physical, mechanical and optical properties revealed that amorphous silica obtained by the pulsed electric current heating technique has the same density, refractive index, elastic modulus and absorbance as fused silica.
