Metal Filament Light Bulb
First experiments with electricity to produce light was carried out in the early 19th century. By the end of the 1900's, only the Edison carbon-fiber lamp had sufficient durability. This has been used successfully in the public and private sector, if the infrastructure was available (electrical supply). But had in comparison with the gas mantle or Welsbach mantle lamp a much worse light intensity and quality of light.
Auer as a visionary realized that the future belonged to the electric light. The carbon filament lamp could technically hardly be further improved and was protected by patents. He expected the solution in a metal filament lamp, which promised better mechanical stability and above all by a higher annealing temperature better efficiency and better light in terms of light color and brightness. Therefore, he started his research on the metal filament lamp already while the gas mantle light just earned its technical and economic successes.
Auer was looking for a material that was electrically conductive and chemically inert. Above all, it should have the highest possible melting point. That's why he chose the Osmium. At about 3100 ° C this had the highest melting point of all known metals. However, it quickly became apparent that the very brittle material was extremely difficult to process into a very thin wire. With his innate perseverance, determination and a certain fearlessness (as a chemical compound, the Osmium is very poisonous) he began to search for an economically suitable manufacturing process. In this context, he appeared as a pioneer in powder metallurgy (a manufacturing process of metallurgy) in appearance.. The manufacturing processes of powder metallurgy allow the production of compact metals and fittings without having to melt the raw materials. Carl Auer von Welsbach carried out countless experiments and in 1898 patented the "Paste" process, which became world famous.
Finely ground osmium powder and some sugar solution were mixed to a soft paste, pressed through a die and made uniformly about 0.1 mm thick filaments. After drying and annealing, a pure, porous osmium wire remained. The experiments and the start of production took place in the Atzgersdorf factory of the "Österreichische Gasglühlichtgesellschaft". From 1906 to 1988, the OSRAM incandescent lamps were manufactured here in what is now Vienna's Liesing district. In Treibach, an osmium plant was quickly set up, in which the production of the osmium filaments and also further research was advanced. Auer showed the first fully developed experimental lamps to the shareholders of the "German Gasglühgesellschaft Aktiengesellschaft" (Degea, DGA) on 23 January 1901.
The osmium lamp showed in practical operation in comparison to a carbon filament lamp, above all, a much better efficiency (about 3 times the light output). The life was more than 1000 hours and was therefore very good. 1905 cost an osmium lamp with today's currency approx. 24 € and a carbon thread lamp approx. 3 €. It is also interesting, however, that the Auer Company bought back a burnt-out osmium lamp at the price of about € 4.50 - the osmium is very rare and therefore only limited available and expensive.
In the background, the laboratory of Auer and competitors continued to research to improve the production of light. Especially on the metal filament incandescent lamp, where above all other high melting point metals (e.g., tantalum) have been tested and used. Ultimately, the error of the literature was recognized and Tungsten identified as the metal with the highest melting point and from about 1906 used as the most suitable material for filaments. On April 17, 1906, the trademark OSRAM was registered as a word mark for "electric incandescent and arc light lamps by the Auer Society (German Gasglühlicht-Anstalt, DGA) at the Imperial Patent Office in Berlin. The Auer Company together with AEG and Siemens & Halske founded OSRAM G.m.b.H. & KG - in 1919 she started her business.
OSRAM = Blend word from OSmium - wolfRAM
Carl Auer von Welsbach made the decisive scientific contribution to the development of the metal filament lamp. Until 1913, only his powder metallurgy paste method was used. The economic success of the Auer-Oslampe was not very significant considering the high development costs and the short marketability of only about 5 years. Further profit after the introduction of tungsten as filament remained Auer refused, since he had specified in the patent expressly only osmium.