Method for producing a component of rare earth metal-doped quartz glass

A method of producing a component that consists at least in portions of a rare earth metal-doped quartz glass, the method comprising:

• (a) providing an intermediate product containing voids and consisting of a SiO2 raw material doped with rare earth metal;
• (b) introducing the intermediate product into a sinter mold with an interior bordered by a carbonaceous mold wall;
• and
• (c) melting the intermediate product into the component by gas pressure sintering at a maximum temperature above 1500° C., a shield being arranged between the mold wall and the intermediate product,
• characterized in that a bulk material of amorphous SiO2 particles with a layer thickness of at least 2 mm is used as the shield, the softening temperature thereof being at least 20° C. higher than the softening temperature of the doped SiO2 raw material, and the bulk material being gas-permeable at the beginning of the melting of the intermediate product according to the method step, and the bulk material sintering during melting into an outer layer that is gas-tight to a pressure gas, characterized in that the bulk material has a gas permeability which is defined by a Darcy coefficient in the range of 1.6×10−11 m2 to 3×10−11 m2, and that the bulk material has a grain size distribution which is characterized by a D10 value between 150 and 250 μm and by a D90 value between 350 and 450 μm.

A method of producing a component that consists at least in portions of a rare earth metal-doped quartz glass, the method comprising:

• (a) providing an intermediate product containing voids and consisting of a SiO2 raw material doped with rare earth metal;
• (b) introducing the intermediate product into a sinter mold with an interior bordered by a carbonaceous mold wall;
• and
• (c) melting the intermediate product into the component by gas pressure sintering at a maximum temperature above 1500° C., a shield being arranged between the mold wall and the intermediate product,
• characterized in that a bulk material of amorphous SiO2 particles with a layer thickness of at least 2 mm is used as the shield, the softening temperature thereof being at least 20° C. higher than the softening temperature of the doped SiO2 raw material, and the bulk material being gas-permeable at the beginning of the melting of the intermediate product according to the method step, the bulk material sintering during melting into an outer layer that is gas-tight to a pressure gas, characterized in that gas pressure sintering comprises:
• (a) a pretreatment which comprises a heating up of the intermediate product to a temperature in the range between 1000° C. and 1300° C. with application and maintenance of a negative pressure,
• (b) melting the intermediate product at a temperature above 1500° C. at a negative pressure and for a melting period of at least 30 min, wherein the bulk material sinters into the gas-impermeable outer layer, and
• (c) a pressure treatment of the molten intermediate product at a temperature above 1500° C. in an inert gas atmosphere under an overpressure in the range between 2 bar and 20 bar for a period of at least 30 min.