OH CONTENT DEPENDENCE OF VISCOSITY OF VIT REOUS SILICA

Viscosity of various types of vitreous silica was measured by a cantil ever-beam-bending method having been used in industry. The viscosity m easured by this method agreed with the value measured by a standard be am-bending method for the same sample, and temperature dependence of v iscosity are consistent with those reported in literature using variou s measurement methods. OH content dependence of the viscosity at 1200 degrees C was measured. There are two groups of vitreous silica, each of which can be represented the viscosity by a decreasing function of OH content; one group is fused quartz (FQ) produced by melting natural quartz powder, and another group is synthetic fused silica (SFS) prod uced by flame hydrolysis of SiCl4. The viscosity of FQ is higher than that of SFS at the same OH content.