the R & D Process Doped Tungsten

Until 1909 , the U.S. General Electric Company Coolidge (wDcoolidge) via powder metallurgy tungsten billet was then produced by machining ductile at room temperature with a tungsten filament , thereby laying the foundation tungsten processing industry , also laid the foundation powder metallurgy . However, this " ductility " tungsten filament in the light bulb lit showed significant brittleness. In 1913, Ping Qi (Pintseh) invented the thorium tungsten wire ( thorium oxide content of 1 % to 2% ) , so that the incandescent filament fragility greatly reduced. Initially, the filament sag ( see tungsten Hang sagging performance ) is not a problem , because the filament is straight wire , but after 1913 , Langmuir (Langmuir) will be replaced by straight wire spiral wire , so that when the light bulb when used , the high operating temperature and weight of the role of the filament sag, thus pure tungsten and tungsten are difficult to meet community requirements . In order to solve tungsten droop and short life and other issues, in 1917 , Perth (A.Pacz) invented the high temperatures , " no deformation " of the tungsten filament . At first, he used when in the preparation of pure tungsten Woe roasting fire tower tungsten trioxide , stumbled with this reduction of tungsten trioxide proceeds made ​​from tungsten powder tungsten spiral , after recrystallization exception mysteriously no longer droop.

Then, after 218 repeated experiments , he finally found that adding potassium tungstate and sodium silicate , after reduction , pressing, sintering and processing the obtained tungsten wire , a fairly coarse recrystallized grain structure neither soft and anti- sagging, this is the earliest non- sag tungsten wire . Perth discoveries laid the basis for the production of non- sag tungsten , until now, the United States does not sag tungsten wire is still called " 218 tungsten wire " to commemorate this major discovery in Perth . However, the first production does not sag tungsten filament brittle than male serious that some insist on using Vitex tungsten bulb factory for the filament. But with no sag tungsten production process of continuous development and improvement , people gradually realized by simultaneously adding the potassium tungsten oxide , silicon, aluminum compounds , can make the tungsten filament at high temperatures with a good anti- sag performance, but by then after crystallization has satisfactory ductility at room temperature . This is now commonly known as "AKS tungsten wire ," or " does not sag tungsten wire " or " doped tungsten wire ." It has many excellent properties , and become the electric light and electronic industries as an important base material . A brief history of the development of tungsten industry from the outset with the light bulb industry closely linked . In 1878 , Edison (TA Edison) invented the carbon filament light bulbs. But this lamp there is a serious disadvantage , primarily life is too short .


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