Abstract: The invention concerns a device (1) for sintering of a porous mold body (2) in a gas-tight chamber (3), with the mold body (2) hanging loose from a link chain (7) so that it can be fed continuously to a heating zone (5). In the area of the upper boiler (10), the traction direction of the link chain (7) is reversed by a deviation wheel (11). The tensile force is transmitted via a traction rope (13) that can be taken up on a take-up reel (14), such take-up reel (14) being driven by a drive (16) arranged outside the chamber (3). A drive shaft (15) for the take-up reel (14) provides for easy sealing of the duct (18) towards the chamber (3), because only a rotation and not a simultaneous axial displacement is required for the hoisting movement, and moreover, because the duct (18) is arranged at a spatial distance from the heating zone (5).

Abstract: A glass composition to be softened is fed to a heating zone and is shaped continuously into a cylindrical component in a deformation zone, and the cross-sectional geometry of the component is determined. A feed device, a heating device, and a take-off device are provided, and a glass composition is supplied continuously by the feed device to the heating device, where it is softened, the component being formed from the softened glass composition by means of the take-off device under formation of a deformation zone. To produce a component with only slight deviations from the desired cross-sectional geometry and to provide a flexible apparatus suitable for this purpose, the glass composition is locally heated or cooled in at least one deformation area, which extends over only a part of the circumference of the deformation zone, as a function of a determined deviation of the cross-sectional geometry from a nominal geometry.

Abstract: A method for measuring trace quantities of OH groups in quartz glass comprises preparing a set of test pieces comprising a reference test piece from a blank of a quartz glass body whose OH group content is known and a sample test piece from a quartz glass body whose OH group content is to be measured, having two planar planes faced to each other, setting the sample test piece and the reference test piece in an infrared spectrophotometer; successively irradiating perpendicular to one of the two planar planes an incident infrared radiation in a wavelength region of approximately 2500 nm to approximately 2950 nm, while simultaneously detecting the outgoing radiation spectrum from the other plane; obtaining the difference of the outgoing radiation spectrum of each of the test pieces; selecting the absorbance peak assigned to OH groups at a wavelength of 2720 nm to obtain the peak height thereof; and calculating the concentration of OH groups from the peak height in the sample test piece.

Abstract: In a known procedure for manufacture of a quartz glass body, a glass starting material and fuel gas are fed to a rotationally symmetrical deposition burner (1) having several annular gap nozzles (7-9) and being formed by coaxial arrangement of a number of quartz glass tubes (2-5), such glass starting material in a burner flame forming SiO2 particles which, under back and forth motion of the deposition burner (1) along the longitudinal axis of a rotating mandrel (12), are deposited on such rotating mandrel under formation of an essentially cylindrical porous blank. To enable replacement of such deposition burner without major efforts in terms of work and costs, the procedure of the inventioin proposes to use a deposition burner (1) the annular gap nozzles (7- 9) of which have gap widths with a maximum dimensional deviation of 0.