Patent ID: 8863552

Claim:
A process for producing a shaped body, comprising: a) providing fused silica in amorphous form having an SiO 2 content of at least 99.5% by weight in the form of essentially amorphous SiO 2 grains of which not more than 5% have a diameter greater than 15 mm, wherein the proportion [% by weight] of particle size<0.3 mm is between 40% and 60% and the proportion [% by weight] of particle size 0.3 mm to 1.0 mm is between 20% and 30% and the proportion [% by weight] of particle size 1.0 mm to 6.0 mm is between 20% and 30%, b) adding substantially alkali-free water to the fused silica grains to produce a slip without any stabilizers, with a ratio of fused silica grains to water being set so that the slip has a nonnewtonian and rheopexic flow behavior, c) casting the slip into a mould which comprises a hollow body having the inverse shape of the shaped body to be produced, d) drying the slip to give an intermediate body, e) sintering the intermediate body at a sintering temperature at which at least part of the fused silica is transformed from the amorphous modification into a crystalline modification, and f) cooling the sintered shaped body to a temperature below 300° C. so that a microstructure containing crystalline SiO 2 is formed.