In 1906, the tungsten filament was introduced. Tungsten metal was initially not available in a form that allowed it to be drawn into fine wires. Filaments made from sintered tungsten powder were quite fragile. By 1910, a process was developed by William D. Coolidge at General Electric for production of a ductile form of tungsten. The process required pressing tungsten powder into bars, then several steps of sintering, swaging, and then wire drawing. It was found that very pure tungsten formed filaments that sagged in use, and that a very small "doping" treatment with potassium, silicon, and aluminium oxides at the level of a few hundred parts per million greatly improved the life and durability of the tungsten filaments. COUNT 5
QSN1 What was the problem with manufacturing the tungsten filament? ANS1 Tungsten metal was initially not available in a form that allowed it to be drawn into fine wires. QSN2 Who developed the ductile form of tungsten? ANS2 William D. Coolidge QSN3 When was the ductile form of tungsten invented? ANS3 1910 QSN4 When was the tungsten filament introduced? ANS4 1906 QSN5 What other materials were combined with tungsten? ANS5 potassium, silicon, and aluminium oxides