Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01K—ELECTRIC INCANDESCENT LAMPS
  • H01K3/00—Apparatus or processes adapted to the manufacture, installing, removal, or maintenance of incandescent lamps or parts thereof
  • H01K3/02—Manufacture of incandescent bodies

Definitions

• My invention relates to improvements in the process of manufacturing tungsten filaments and in the filaments themselves.
• Helically wound drawn filaments such as are at present frequentlyused in gasfilled glowlamps, are exposed to very high temperatures, owing to which the filaments become deformed and sag.
• the finished filament contains 0005 to 0.1% of a chromiumoxygen or manganeseoxygen compound.
• tungsten powder is pressed into rods, the rods are treated and then the product treated is further worked up until the desired dimensions are reached.
• an alkali salt of a chromiumoxygen or manganeseoxygen compound is added to the starting product and tungsten powder of a chromiumoxygen or manganeseoxygen compound instead of one single alkali salt.
• the starting product to which the alkali salt is added may be for example tungsten powder which should then have the necessary fineness.
• the fineness of the tungsten powder can be regulated by properly choosing the circumstances in reducing the tungsten oxide.
• the reducing temperature has a direct influence on the fineness of the powder obtained. It can be ascertained by experiments how the circumstances during the reduction process should be chosen in order to obtain a powder of a definite fineness.
• a better and easier mingling of the compound added with the tungsten powder is ensured by adding a water solution of the compound to pure tungsten acid serving for the treating of the tungsten powder.
• a solution of the alkali salt may be added to tungsten acid, the mixture may be dried and then reduced under such circumstances that the tungsten powder obtained is so finely divided that in the product treated, a quantity of a chromiumoxygen or manganeseoxygen compound of at least 0.005% and at the utmost 0.1% remains.
• the percent-age of alkali salt which is initially added is materially higher than the percentage of the compound which remains in the product treated. It depends on the fineness of the tungsten powder also on the nature of the substance chosen. For any particular case, the necessary percentage of the primarilyadded compound may be ascertained by experiments.
• potassium bichromate may for example be added to'tungsten powder being so finely divided that 5 grams of the powder requires 40 seconds to fully settle down in com. of a mixture of alcohol and ether (1:1). It 0.24% of potassium bichromate is added, the product treated is found to contain a residue of 0.0050.03%
• Impure tungsten acid is in the known manner dissolved in chemically pure ammonium hydroxide, filtered and crystallized.
• the powder is further worked up in the known manner. It is pressed into rods, then it is fired and treated whereby a considerable part of the potassium bichromate volatilizes.
• the rod treated is then further mechanically worked up for example by hammering and rolling and lastly it is drawn into the diameter desired.
• the wire obtained may still be coiled, whereupon it is ready for use as a filament.
• my invention contemplates a finished metal or filam'ent for incandescent lamps which contains a small per cent of a sag preventing constituout, the object of the constituent being to reduce or eliminate the tendency of the finished metal or filament to sag during operation.
• said salt bein an alkali chromium salt and serving to re uce the tendency of the filament to sag.
• a tungsten filament for an incandescent lamp consisting of tungsten with a small per cent of a compound of one of the acid elements located in the periodic table in the righthand half of the third horizontal column, the per cent of the compound being less than 0.1% of the tifngsten, said compound operating to modify the tungsten con;- stituent to minimize the tendency of the fila ment to sag.
• a tungsten lamp consisting of tungsten with a small per cent of a compound of chromium, the per cent'of the compound being less than 0.1% of the tungsten, said compound operatfilamentfor an incandescent 7

Landscapes

• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Powder Metallurgy (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=19779082

Family Applications (1)

Country Status (4)

Cited By (2)

• 0
  • NL NL15542D patent/NL15542C/xx active
• 1924
  • 1924-04-24 US US708819A patent/US1662027A/en not_active Expired - Lifetime
  • 1924-05-02 FR FR581042D patent/FR581042A/fr not_active Expired
  • 1924-05-12 GB GB11753/24A patent/GB216124A/en not_active Expired

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