Schott Ag

Schott Glaswerke

Wolfgang Semar

Waldemar Weinberg

Ralf Biertuempfel

Bernd Wölfing

Wolfgang Pannhorst

Ralf Bonitz

Ralf Biertümpfel

Thomas Kraus

Ulrike Stoehr

Nicole Surges

Matthias Redey

Janusz Zborowski

Bartolome Aloy

Michael Dunkl

Klaus Mirsch

Michael Hahn

Reiner Best

Ralf Biertuempel

Monika Burkner

Werner Waidhas

Martin Schäfer

Methods for press molding a glass body, especially for optical applications, without additional grinding and polishing steps are described. One method is performed with a press mold having an upper mold part, a lower mold part and, if necessary or desired, a ring. In order to improve the quality of the products, especially glass bodies of larger diameters, a voltage is applied across the upper mold part and the lower mold part when the glass body is within the press mold and a pressing force is applied to the glass body when the temperature of the glass body matches the temperature of the press mold. Alternatively, in another method the press mold is cooled after it reaches a predetermined temperature and the pressing force is applied to the glass body in the mold after exceeding the sticking temperature (T).

Method for blank pressing of optical components

The optical lens, especially for a motor vehicle, is provided with a soft-focus effect, e.g. to soften a light-dark boundary on an illuminated surface. For this purpose the optical lens has an optically active surface (') provided with an embossed fine structure () extending radially outward in a direction from an optical axis (O) toward an outer periphery (P) in an undulating form and an embossed microstructure () superimposed on the embossed fine structure (). The fine structure () has a roughness that is greater than that of the microstructure (). The fine structure () preferably has a roughness of from 1 &#x3bc;m to 10 &#x3bc;m and the microstructure () has a roughness (h) in a range of from 0.1 &#x3bc;m to 2.5 &#x3bc;m.

Optical lens soft-focus effect

A method for the manufacture of dense-sintered glass-ceramic shaped objects which have a coefficient of thermal expansion, .alpha., of -0.5.times.10.sup.-6 /K to 1.8.times.10.sup.-6 /K in the range between 20.degree. C. and 700.degree. C. whereby ceramizable glass powder and/or glass-ceramic powder from the system Li.sub.2 O-Al.sub.2 O.sub.3 -SiO.sub.2 is slip-cast by means of porous molds, dried, pretempered if necessary at temperatures up to 600.degree. C., vitrified and then sintered until the sintering temperature is reached up to relative densities of greater than 0.96 and ceramized, and whereby the glass powder and/or the glass ceramic-powder is prepared in a first grain size fraction of less than 63 .mu.m, in particular less than 45 .mu.m, and in a second grain size fraction of less than 7 .mu.m, in a ratio of the fractions to one another between 2:1 and 4:1, to form a stable, pourable slurry. The method can be used for the manufacture of industrial ceramics, but also for the manufacture of complex-shaped, large-volume and thin-walled hollow containers, in particular for use as cooking utensils which are resistant to thermal shock, as well as for dinnerware, solid ceramic castings and composites.

Method for the manufacture of dense-sintered glass ceramic moldings

A process for producing dense-sintered cordierite bodies and zirconium dioxide-reinforced cordierite bodies with a maximum of 50% by weight of ZrO.sub.2 is described, wherein a powder of cordierite particles of stoichiometric composition and, if appropriate, ZrO.sub.2 of a particle size of less than 3 .mu.m is heated at temperatures above 800.degree. C. at a rate of temperature rise of less than 5.degree. C. per minute. Virtually pore-free sintered bodies having outstanding mechanical properties can be produced by the process.

Process for producing dense-sintered cordierite bodies

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Mainz, Germany

Wolfgang Semar