| 摘要 |
PROBLEM TO BE SOLVED: To provide a tungsten electrode having long service life and high performance by reducing Si to 5 ppm or less capable of preventing the generation of blackening on the basis of a fact that blackening of a lamp, which decides lamp service life, is due to scattering of Si, which is mainly contained in electrodes, from the electrodes heated at a high temperature. SOLUTION: The tungsten electrode contains less than 5 ppm of Si, 5-20 ppm of K and 5-20 ppm of Al, and residual parts are practically formed of tungsten, and the tungsten electrode has 19100 kg/cm<SP>3</SP>or more of density. COPYRIGHT: (C)2005,JPO&NCIPI
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