Microstructure And Luminance Properties Of Integrated Translucent Alumina Tube Used In Metal Halide Lamps

The integrated translucent alumina tube used in metal halide lamps have been fabricated by gelcasting process. The influence of sintering process, various sintering fluxes on the micro- structure was discussed. Furthermore, the relation between the luminance and the microstructure was also investigated. The results reveal that when the sintering temperature is 1750 degrees C, the holding time is 6h, the compact product whose average grain size is about 20 mu m could be obtained; the triple dopant combinations of MgO, Y2O3, La2O3 can promote sintering and improve the microstructure more than double, single dopants and the contents of sintering flux are 99.6wt%Al2O3, 0.2wt%MgO, 0.1wt.%Y2O3 and 0.1wt.%La2O3 respectively; The transmittance increases with the pore decreaseing, the grain size enlarging and the degree of the surface finish improving, the average in line transmittance is about 40%.