REFRACTORY METAL OXIDE REFLECTOR COATING ON LAMP ENVELOPE

摘要

The adherence of an optically reflective coating of refractory metal oxide particles such as ZrO2 or Al2O3 on a fused silica discharge tube surface is improved severalfold by an adhesion layer consisting of colloidal aluminum oxide and boric oxide powders. The adhesion layer may be first applied and dried, the refractory metal oxide coating then applied, and the quartz tube then heated to a temperature greater than 460.degree.C, the melting point of boric oxide. The refeactory metal oxide particles may also be applied admixed with the colloidal aluminum oxide and the boric oxide. The improved coating strength permits the use of a thicker layer of refactory metal oxide for higher optical and thermal reflection.