Original von elmar2001
warum kann man zwei separat gefertigte hälften nicht zusammenkleben?
Das Zusammenfügen von 2 unterschiedlich gefärbten Lünettenhälften ginge im Prinzip schon. Meiner Meinung nach liegt das Problem darin, dass Rolex noch nicht ganz zufrieden ist mit der Entwicklung von farbbeständiger roter Keramik.


Aber vielleicht kommt es zur Basel 2009 --->



Es gibt da die Patentanmeldung EP 1 887 052 A1 oder US2008026207 A1 mit dem Titel PIGMENTED CERAMIC PIECE. Diese wurde von Alke Fink-Petri und Heinrich Hofmann im Auftrag des Anmelders Rolex SA erarbeitet.

Heinrich Hofmann ist Professor am Powder Technology Laboratory der Hochschule Ecole Polytechnique Fédérale de Lausanne. Alke Fink-Petri ist (war?) an diesem Institut eine Assistentin von Prof. Hofmann. Rolex hat die Lösung des Problems mit roter Keramik zumindest teilweise an externe Wissenschftler outsourced.


In der oben genannten Patentanmeldung wird ganz speziell auf das Problem mit der roten Färbung bei Keramik eingegangen.

[0002] It is known that one of the current trends in timepieces, for example, as well as in jewels or jewelry, is to turn to pieces or objects in ceramic, this trend nevertheless is frustrated by the impossibility of obtaining the entire range of colors and deep colors, no matter the pigment or ceramic utilized.
[0003] In particular, it is difficult, if not impossible, to obtain to date certain ranges or varieties of red that are strong, bright and stable through time.
[0004] Numerous tests have been done in this matter, including using coated nanoparticles, especially silica-coated nanoparticles as pigments, but the final ceramics obtained are still known to have muddy and "dirty" colors, rather similar to an undefined brown.
[0005] The object of the invention precisely aims to overcome these disadvantages by precisely proposing timepiece components, jewels or jewelry pieces made in ceramic in the entire range of desired colors, particularly in the red range.
...
[0012] As indicated above, the various attempts made until now utilizing nanoparticles as pigments unfailingly lead to the "dirty" colors mentioned previously, especially in the red range, regardless of the parameters utilized and the care given to developing the ceramic, a phenomenon that is sometimes accompanied by a color shift to blue.
[0013] This may be attributed to, as observed, several factors all intervening during the sintering operation of the ceramic piece: on the one hand, diffusion of metal species across the silica coating when the latter is not crystallized, on the other hand, a phenomenon of coalescence of the nanoparticle cores comprising the pigment when they are polynuclear (see below), and still on the other hand, an agglomeration or agglutination of pigment nanoparticles between them.
[0014] On the contrary, when silica is crystallized, this coating is used as a diffusion barrier for the metal comprising the core when the nanoparticle is subjected to high temperatures. There is no coalescence or agglutination.
[0015] The transformation of amorphous silica into crystallized silica coating the nanoparticles before their utilization as pigments is done by a thermal treatment at a temperature of ...
...
[0017] Surprisingly, there is no migration or coalescence even if the ceramic is developed at a temperature that is markedly greater than that of the melting point of the metal or alloy comprising the nanoparticle core or cores, with a color that remains "clean" and strong.

Und im Patentanspruch Nr. 8 wird auch die mögliche Verwendung für eine Lünette offenbart
8. The piece according to claim 1, wherein the piece consists of a watch container, a dial, a bezel, a bracelet or pins.


In der Erfindung geht es aber nicht nur um die Einbettung von Pigmenten in Keramik, es geht vor allem auch um die Herstellung von solch speziellen Nanopartikeln, die das Pigment bilden:

[Abstract] The invention relates to a piece comprised in part or in full of a pigmented ceramic in which the pigment is comprised of nanoparticles based on a metal from column IB of the periodic table of the elements or of an alkaline metal, or an alloy of both, coated with a layer of silica, the silica being crystalline silica, particularly cristobalite or tridymite. The ceramic is preferably zirconia or alumina. The nanoparticle silica is crystallized, for example, by a thermal treatment in air or under inert gas at temperatures of between 900 DEG C. and 1400 DEG C. The piece is made by sintering a nanoparticle/ceramic mixture in air or under inert gas at temperatures of between 900 DEG C. and 1250 DEG C.