A method for producing hollow glass microspheres includes preparing an aqueous suspension of starting materials including finely ground glass and waterglass. Combustible particles are produced from the suspension and are mixed with an AlO(OH)-containing pulverulent release agent. The mixture of combustible particles and release agent is introduced into a combustion chamber of a furnace where it is expanded at a combustion temperature which exceeds the softening temperature of the finely ground glass, to form the hollow microspheres. Hollow glass microspheres produced according to the method are also provided.

Hollow glass microspheres are produced. An aqueous suspension is prepared of starting materials of finely ground glass and waterglass. Firing material particles are produced from the suspension and are mixed with a pulverulent release agent. The mixture of firing material particles and release agent is introduced into a firing chamber of a furnace where it is expanded at a firing temperature which exceeds the softening temperature of the finely ground glass, to form the hollow microspheres. The release agent is Al(OH).sub.3 and dehydroxylated kaolin.

Hollow glass microspheres are produced. An aqueous suspension is prepared of starting materials of finely ground glass and waterglass. Firing material particles are produced from the suspension and are mixed with a pulverulent release agent. The mixture of firing material particles and release agent is introduced into a firing chamber of a furnace where it is expanded at a firing temperature which exceeds the softening temperature of the finely ground glass, to form the hollow microspheres. The release agent is Al(OH).sub.3 and dehydroxylated kaolin.

A method for producing sulfide glass wherein phosphorus sulfide satisfying the following formula (1) is used as a raw material:
100A/B37(1)
wherein in the formula, A is peak areas of peaks that appear at peak positions in a range of 57.2 ppm or more and 58.3 ppm or less, and 63.0 ppm or more and 64.5 ppm or less in .sup.31PNMR spectroscopy, and B is the total of peak areas of all peaks measured in .sup.31PNMR spectroscopy.

A method for producing sulfide glass wherein phosphorus sulfide satisfying the following formula (1) is used as a raw material:
100A/B37(1)
wherein in the formula, A is peak areas of peaks that appear at peak positions in a range of 57.2 ppm or more and 58.3 ppm or less, and 63.0 ppm or more and 64.5 ppm or less in .sup.31PNMR spectroscopy, and B is the total of peak areas of all peaks measured in .sup.31PNMR spectroscopy.

A high strength glass fiber is prepared by following steps: weighing raw materials according to a mass percentage of 50-60% silica sol, 24-31% aluminum sol, 8-11% magnesia, 4-5% calcium oxide, 0.1-2% titanium dioxide, 0-0.5% ferric oxide, 0.5-2% niobium pentoxide, 0.5-1.5% antimony trioxide, 0.3-1.5% bismuth nitrate, and 0.1-0.5% boric acid. Deionized water is added. The raw material undergoes mixing by ball milling, spray-drying, calcining, isostatic pressing, melting, and wire-drawing. The invention adopts silicon sol, aluminum sol and bismuth nitrate. Through ball milling and spray-drying, silicon aluminum barium plasmas is evenly coated on surface of other oxide powders. Then nano particles, of silica, alumina and bismuth oxide are obtained by calcining. Under the effect of the high specific surface energy of nano particles, and the close contact of each component, high strength glass fiber is obtained in relatively low fiber drawing temperature while the glass melting temperature and time are significantly reduced.

A high strength glass fiber is prepared by following steps: weighing raw materials according to a mass percentage of 50-60% silica sol, 24-31% aluminum sol, 8-11% magnesia, 4-5% calcium oxide, 0.1-2% titanium dioxide, 0-0.5% ferric oxide, 0.5-2% niobium pentoxide, 0.5-1.5% antimony trioxide, 0.3-1.5% bismuth nitrate, and 0.1-0.5% boric acid. Deionized water is added. The raw material undergoes mixing by ball milling, spray-drying, calcining, isostatic pressing, melting, and wire-drawing. The invention adopts silicon sol, aluminum sol and bismuth nitrate. Through ball milling and spray-drying, silicon aluminum barium plasmas is evenly coated on surface of other oxide powders. Then nano particles, of silica, alumina and bismuth oxide are obtained by calcining. Under the effect of the high specific surface energy of nano particles, and the close contact of each component, high strength glass fiber is obtained in relatively low fiber drawing temperature while the glass melting temperature and time are significantly reduced.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, ii.) Making a glass melt from the silicon dioxide granulate in an oven, and iii.) Making a quartz glass body from at least a part of the glass melt, wherein the oven comprises a hanging sinter crucible. The invention also relates to a quartz glass body which is obtainable by this process. The invention further relates to a light guide, an illuminant and a formed body which are each obtainable by further processing the quartz glass body.

One aspect relates to a process for the preparation of a quartz glass body. The process includes providing a silicon dioxide granulate from a pyrogenically produced silicon dioxide powder, making a glass melt out of silicon dioxide granulate, and making a quartz glass body out of at least part of the glass melt. The size of the quartz glass body is reduced to obtain a quartz glass grain. The quartz glass body is processed to make a preform and an opaque quartz glass body is made from the preform. One aspect further relates to an opaque quartz glass body which is obtainable by this process. One aspect further relates to a reactor and an arrangement, which are each obtainable by further processing of the opaque quartz glass body.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing silicon dioxide particles, ii.) Making a glass melt out of the silicon dioxide particles in an oven and iii.) Making a quartz glass body out of at least part of the glass melt, wherein the oven has a gas outlet through which gas is removed from the oven, wherein the dew point of the gas on exiting the oven through the gas outlet is less than 0 C. The invention further relates to a quartz glass body which is obtainable by this process. The invention further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.