How does "China bulb light factory" lamp life end ?

A lit "China bulb light factory" incandescent filament temperature up to 3000 ℃. It is because of the hot filament to produce light radiation, only to lamps emit a bright light. Because some of the high temperature gas tungsten atoms are evaporated and deposited on the glass surface of the lamp, the lamp black, the "China bulb light factory" are caused by incandescent "bellied" shape, which is deposited in order to make Atomic Energy of tungsten down on a relatively large surface disperses. Otherwise, the light bulb in a very short period of time will be blackened. Since the filament is constantly being sublimated, it will be tapering off until the last, when a "" bulb life will be over.