Transparent polycrystalline alpha-alumina tube prodn - for high-pressure sodium vapour lamps

摘要: Polycrystalline alpha-alumina tubes for high-pressure sodium vapour lamps are produced from a plasticised based powder (is not >5% gamma-Al2O3) contg. >=90% Al2O3 (pref. 99.5% Al2O3) and some deliberately introduced metal cpd. contaminants moulded by cold extrusion an abrasion-resistant, sintered alumina die at 0.5-150 t./cm2. 75 t/cm2) with reduction degree of >=80% 85%), opt. additional mechanical, pneumatic or hydraulic shaping. The body is then embedded in powdered alumina, heated first 1400 degrees C 1250 C), freed the powder, finally >1800 1980 C, using plasma flame) vacuum, neutral reducing gas atmos. >=15 mins. transparency tube 85-95% visible light. yield up to 110 lumen/W.