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Abstract

The use is described of oxide ceramic materials for compression molds for shaping elements made from glass or a glass-containing ceramic and having high surface quality and tight tolerances. The materials are polycrystalline, monophasal or polyphasal materials which are contact-inert towards the optical elements to be pressed and which, in addition, have significantly better mechanical and thermal properties than monocrystalline substances, which, in principle, exhibit an anisotropic behavior as a consequence of their geometrical anisotropy. The material intended for use according to the invention can comprise a Al.sub.2 O.sub.3 ceramic or a ZrO.sub.2 -- and/or HfO.sub.2 -containing ceramic. The material can also be built up in several phases, i.e. can contain a matrix component and at least one particle component dispersed discretely in it. They are preferably ZrO.sub.2 -containing ZTC, PSZ or TZP ceramics, which, for the application according to the invention, have excellent thermomechanical properties which are founded in the reaction mechanism and, above all, in the crystallography of their components. Mechanisms such as so-called 'stress-induced conversion toughening' and 'microcrack toughening' play an important part here. With the materials used, compression molds can be produced for reworking-free shaping of optical elements having planar and/or spherical and/or aspherical convex and/or concave surfaces of high surface quality and dimensional accuracy, while noting improved production processes.

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First Claim