Verneuil process
The Verneuil process is a crucible-free flame melting process for the production of synthetic gemstones that was published in 1902 by the French chemist Auguste Verneuil . Today, the Verneuil process is used to manufacture sapphire glass from synthetic sapphire , originally the process was developed for ruby synthesis .
execution
A metering device contains a high-purity powdery material that is melted in the burner tube of a kiln with hydrogen and oxygen and solidified layer by layer on a crystal nucleus. While the crystal in the form of a so-called “cultivation pear” grows by around 5–20 mm per hour, it is slowly moved downwards using a lowering device so that it remains in the ideal burning zone of the furnace. In industrial plants, a large number of such devices are usually arranged (even 1000 and more). The crystals grown with the Verneuil process are essentially pear-shaped and about 20 to 50 mm in size.
literature
- K. Nassau: “Reconstructed” or “Geneva” ruby. In: Journal of Crystal Growth. 5, 1969, pp. 338-344, doi: 10.1016 / 0022-0248 (69) 90035-9 .
- DC Harris: A peek into the history of sapphire crystal growth. In: Proceeding of SPIE. Volume 5078, September 26, 2003, pp. 1-11, doi: 10.1117 / 12.501428 .
- Hans J Scheel: Historical aspects of crystal growth technology. In: Journal of Crystal Growth. 211, 2000, pp. 1-12, doi: 10.1016 / S0022-0248 (99) 00780-0 .
- William Crookes: Gem, Artificial . In: Encyclopædia Britannica . 11th edition. tape 11 : Franciscans - Gibson . London 1910, p. 569–572 (English, full text [ Wikisource ] - here pp. 571–572).
- Klaus-Thomas Wilke: Crystal growth . Deutsch, Thun 1988, ISBN 3-87144-971-7 , pp. 860 ( limited preview in Google Book search).
- Gerhard Fasching: Materials for electrical engineering: microphysics, structure, properties . 4th, unchanged edition. Springer, Vienna / New York 2005, ISBN 3-211-22133-6 , pp. 107 ( limited preview in Google Book search).
Web links
- Detection of synthetic gemstones. (English)
- Source: German patent DE 21 22 937B