A novel route for the production of ultra pure SiO2 crucibles

A novel and cost-effective process is introduced for the production of ultra pure quartz parts on an industrial scale under clean room conditions. Starting with a colloidal SiO2 Sol, SiO2 green bodies are fabricated by a pressure casting process. After drying, the SiO2 preforms are sintered with CO2 laser systems providing a power output of up to 12 kW In contrast to the many applications of high power laser systems the laser optics used widens the laser beam to a spot size of up to 100 mm. It could be shown that state of the art CO2 laser systems are superior to heat sources commonly used for sintering of high purity ceramics since contamination of the material to be sintered can be virtually excluded and large SiO2 preforms can be sintered to graded structures without changing their geometry.