Abstract
Translucent aluminum oxide, a crystalline substance, has transmittivity of some 90%, high corrosion resistance, and high stability in alkali metal vapor at high temperature and pressure, in addition to the high mechanical strength and thermal resistance which are the specific properties of conventional alumina ceramic.
By this new substance being utilized for a discharge tube and the sodium vapor pressure being increased, a sodium-vapor lamp has been developed, which is smaller than conventional and produces white light with a wide spectral band and the luminous efficiency of about 100 lm/W.
This new substance-to-metal sealing is very difficult. The writers sealed this new substance to Ti by reactive alloying method utilizing Ti-Ni. Particularly, paying, attention, to sealing time and the surface condition of this new substance in sealing, we investigated those influences on seal strength and the vacuum tightness, and observed and examined the sealed part by the microscope and the X-ray microanalyzer.
Gained results are as follows.
(1) By reactivealloying method utilizing Ti-Ni, it is possible to seal in vacuum-tight this new substance to Ti.
(2) Sealing surface which is flat and slightly rough, is good to obtain the vacuum tightness.
(3) At sealing temperature of 1000°C, seal strength approaches the saturation condition in 10 minutes to seal, and the seal strength is about 150 kg/cm2.
(4) In the sealed part, the triangular and the lustrous crystal constructions are observed, these parts seem to be Ti2Ni phase.
(5) In the sealing part of this new substance to Ti, three boundary layers are observed. Ti, Ni and Al elements show their own peculiar diffusion distribution in these layers. In this part, a solid solution or a compound of Ti-Al-Ni-O system and Ti-Al-O system is formed, and the combination between this new substance and Ti seems to be completed.
