Method for producing heat-resistant synthetic quartz glass

摘要

A porous silica body with a density of 0.1 g/cm3 to 0.5 g/cm3 and a density variation of less than 30% is subjected to a first heat-treatment in an ammonia-containing atmosphere, a second heat-sintering in non-oxidizing atmosphere, and further heat-treatment at a temperature in the range of 1400 DEG C. to 2000 DEG C. under an increased pressure of 500 kg/cm2 or more in a non-oxidizing atmosphere.