PREPARATION OF GLASS BY SINTERING

Preparation of glass articles by sintering of glass and amorphous powders is considered. The classification of sintering processes includes: (a) sintering of premelted and pulverized glasses; (b) sintering of premelted chemically treated glasses; (c) sintering without melting; (d) sintering with melting. The most interesting class of processes is sintering without, or simultaneously with, melting and it includes preparation of preforms for optical fibers and the sol-gel route for glass preparation. This last route is reviewed in detail. Two main versions are considered: preparation of gels by hydrolysis and polymerization of alkoxides, and sintering of amorphous colloidal powder compacts. The sol-gel processes represent an embryo of a new technology for the production of high-melting glasses (including quartz glass) at relatively low temperatures.