Transparent gamma - alumina for lamp envelopes - made by pre sinterin alumina below alpha-gamma transition temp then at higher temp

摘要

powder with particle size 0.002-0.05 mu made by heating Al(OH)3 or salts is pressed to the required shape, prefired for >2 hours at 1000 degrees C and then finally fired at 1800-1950 degres C >1 hour in a vacuum or hydrogen atmos. When used in metal vapour lamps the envelope allows a spectrum more typical of sunlight to pass through.