MECHANICAL-PROPERTIES EVOLUTION DURING SINTERING OF OPTICAL SOL-GEL SILICA

As the densification of sol-gel derived optical silica monoliths proceeds, the mechanical properties of the material change continuously, corresponding to changes in structure. As shown by flexural, uniaxial compression, diametral-compression and dynamic mechanical testing, the evolution of mechanical properties can be divided into two regions: the first region corresponds to lower sintering temperatures and is characterized by relatively little increase in strength; in the second region, at higher densification temperatures, there is a pronounced increase in strength as densification proceeds. Changes in mechanical properties with densification are best described in terms of topological parameter, λ, the relative genus. © 1990.