公开(公告)号：US20020171363A1

公开(公告)日：2002-11-21

申请号：US09812432

申请日：2001-03-20

Applicant: General Electric Company

Inventor： Curtis E. Scott ,  Mary Sue Kaliszewski ,  Charles D. Greskovich ,  Harry M. Laska

IPC: H01J061/36

CPC classification number: C04B41/009 ,  C04B35/115 ,  C04B41/5361 ,  C04B41/91 ,  C04B2111/805 ,  H01J5/04 ,  H01J9/247 ,  H01J61/302 ,  H01J61/827

Abstract: A high transmittance polycrystalline alumina arc tube for a metal halide discharge lamp is formed by treating an alumina arc tube material having a few percent of closed porosity in a two step process, which provides a high-transmittance arc tube. An initially porous arc tube is formed by extruding or die pressing individual components of the tube from a mixture which includes powdered alumina, assembling the components into an arc tube body, and then partially sintering the components to seal them together. The two step process includes hot isostatic pressing of the partially sintered arc tube and then chemically polishing the surface of the tube. The first, pressing step involves heating the alumina arc tube in an inert atmosphere, such as argon, at a temperature of 1600 to 1900null C. and a pressure of about 700 to 2100 kg/sq.cm. for from about one to three hours. This reduces porosity in the crystalline structure. In the second step, the surface of the tube is immersed in a flux comprising a molten alkali metal borate at moderately elevated temperatures, or coated with a flux material which is heated to form the flux, to remove surface imperfections. The finished arc tube has transmittance values which approach those of single crystal sapphire arc tubes.

Abstract translation: 用于金属卤化物放电灯的高透光率多晶氧化铝电弧管是通过在两步法中处理具有几百个闭孔率的氧化铝弧管材料形成的，这提供了高透光率的电弧管。 通过从包括粉末状氧化铝的混合物挤出或模压管道的各个部件形成最初多孔的电弧管，将组件组装成电弧管体，然后部分烧结组件以将它们密封在一起。 两步法包括热等静压部分烧结的电弧管，然后化学抛光管的表面。 第一个压制步骤包括在惰性气氛（例如氩气）中在1600至1900℃的温度和约700至2100kg / sq.cm的压力下加热氧化铝弧光管。 约一到三个小时。 这降低了晶体结构中的孔隙率。 在第二步骤中，将管的表面在适度升高的温度下浸入包含熔融碱金属硼酸盐的焊剂中，或涂覆有加热以形成焊剂的焊剂材料，以去除表面缺陷。 完成的电弧管具有接近单晶蓝宝石电弧管的透射率值。