DE570606C - Metal vapor arc lamp - Google Patents

Description

GERMAN EMPIRE

ISSUED FEBRUARY 17, 1933

REICH PATENT OFFICE

PATENT LETTERING

CLASS 21 f GROUP 8202

21 f S 120. JO

Siemens & Halske Akt.-Ges. in Berlin-Siemensstadt *) metal vapor arc lamp

Patented in the German Empire on March 4, 1930

Many attempts have been made to produce metal vapor arc lamps with enclosed arc discharge with a metal filling that is solid at room temperature, preferably cadmium 5 or zinc, in the manner of mercury vapor lamps. It was recognized early on that the prerequisite for such lamps to be viable is absolute purity of the metals, in particular absolute freedom from oxides. It turns out, however, that this condition cannot be met, since absolutely clean cadmium or zinc adheres to the ouarz wall and the vessel bursts when it cools down. Attempts have been made about preventing this effect by adding zirconium, gallium and larger amounts of bismuth (about io ° / _0). As far as can be judged from the available literature, however, the economic

ao kung of these additives also only on the impurities that were brought in. A satisfactory service life could not be achieved in any case.

According to the invention, in metal

S5 vapor arc lamps in quartz envelope or high-quartz glass envelope with a filling made of cadmium or zinc or an alloy of these two metals, in which the adhesion to the wall is prevented by adding bismuth to the metal filling, the addition of bismuth between 0.01% ^and <i 1 ° / o of the filling material selected. While an alloy of cadmium less than 2o ° / ₀ Zinc showed already at a relatively high degree of purity no adhesion to the quartz wall more and allowed the construction of a relatively long-lived Ouarzbrenner. With absolute freedom from oxides and complete degassing of the quartz wall, this cadmium-zinc alloy also tended to adhere to the quartz wall. This phenomenon, which had opposed an insurmountable obstacle covering production of high cadmium zinc burner, could be solved by adding a very small amount of me- ^4S tallischem bismuth in a surprising way. It turned out that even a small addition of bismuth is sufficient, as is the case with the slow joint distillation of cadmium and zinc with bismuth in the distillate. Due to the vapor pressure ratio. With the addition of bismuth and cadmium, the amount of bismuth in this case can be estimated at a maximum of one ten-thousandth of the amount of cadmium or one-thousandth of the amount of zinc.

An addition of more than 1 ° / ₀ bismuth is not recommended because the hard evaporating bismuth deposits on the walls of the discharge tube and escapes the same only at very high temperature. With such a small addition of bismuth, as mentioned above, nothing of this phenomenon is noticeable, there

*) The patent seeker stated as the inventor:

Dr.-Ing. Denes Gabor in Berlin.

of the small amounts of bismuth dissolved in cadmium or zinc, only a greatly reduced amount Partial vapor pressure of bismuth corresponds. So by adding bismuth it is An arbitrarily extensive cleaning of the filling and the burner of oxides or oxygen residues is possible and thus the achievement a long service life of the burner has become possible.

Claims (2)

Patent claims: i. Metal vapor arc lamp in quartz envelope or high-quartz glass envelope with a filling of cadmium or zinc or an alloy of these two metals, in which the adhesion of the filler metal to the wall is reduced by adding bismuth to the metal filling, characterized in that the addition of bismuth between 0.01 ° / ₀ and 1% of the filler metal lies. 2. Metal vapor arc lamp according to claim i, characterized by a metal filling, obtained by distilling cadmium and / or zinc together with bismuth.