| 摘要 |
PURPOSE:To prevent the leakage of sodium in a luminous tube to the outside of the tube during operation by through sealing an electric conductor provided with boron nitride film on the outside surface in the aperture of the end of an alumina tube with ceramic cement containing calcium oxide. CONSTITUTION:An alumina tube 1 and an end disk 2 and an electric conductor 6 are sealed together with rings of ceramic cement 8 by heating up to a high temperature and melting the said cement. During the heating aluminum oxide and boron nitride are dissolved in the ceramic cement 8 and crystallized partially under the existence of calcium oxide. Thereby the boron nitride film 7 and the ceramic cement 8 are adhered strongly, and the sealed portions between the hole 3 of the end disk 2 and the conductor 6 and between the alumina tube 1 and the end disk 2 can be made sufficiently airtight. Therefore the leakage of the sodium or the like in the luminous tube to the outside of the tube during the operation of the lamp can be prevented.
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