Abstract: An electronic substrate is provided in the form of a sintered body of polycrystalline alumina ceramic which further contains up to approximately 4% glass forming oxide selected from SiO.sub.2, MgO and ZrO.sub.2 along with about 0.4-2.0% refractory metal oxide to substantially reduce visible transmission in said substrate. In a preferred embodiment, said substrate comprises an elongated member of the ceramic material such as a flat layer which further includes a central cavity region housing an integrated circuit component such as a chip in which may be further provided with cover means for the central cavity in said member that can be formed with the same ceramic.

Abstract: An improved alumina base ceramic guide article is disclosed having sufficient electrical conductivity to remove the static electricity charge from continuously moving textile and synthetic organic polymer filament and tapes when placed in physical contact with said guide article. Specifically said guide article is formed with a sintered polycrystalline alumina ceramic material having a rounded grain size so as not the mechanically abrade the filament or tape members in physical contact therewith and with said ceramic material comprising in approximate weight percent based on the starting batch formulation at least 94% Al.sub.2 O.sub.3, 1-4.5% TiO.sub.2, 0-4% MnO.sub.2, and 0-3% Fe.sub.2 O.sub.3. In the preferred embodiments, the ceramic material contains sufficient TiO.sub.2, Fe.sub.2 O.sub.3, and MnO.sub.2 content to produce a dark uniform color in the final ceramic article.