Abstract: A high-voltage electrical insulator (21) for electrically insulating a thermoelectric module (17) in a spacecraft from a niobium-1% zirconium alloy wall (11) of a heat exchanger (13) filled with liquid lithium (16) while providing good thermal conductivity between the heat exchanger and the thermoelectric module. The insulator (21) has a single crystal alumina layer (SxAl.sub.2 O.sub.3, sapphire) with a niobium foil layer (32) bonded thereto on the surface of the alumina crystal (26) facing the heat exchanger wall (11), and a molybdenum layer (31) bonded to the niobium layer (32) to act as an oxygen permeation barrier to preclude the oxygen depleting effects of the lithium from causing undesirable niobium-aluminum intermetallic layers near the alumina-niobium interface.

Abstract: A high impact sight glass assembly and production method are described, in which the glass lens is fused into an enamel coated metal ring such that the glass lens is fused to the enamel coating and the entire glass area is under compression. The glass lens is placed in the bore of a flange, and the lens and flange ring are heated, whereby the lens flows to conform to the bore of the flange and is fused to the enamel coating.