Abstract: A method is disclosed for making a microwave radar transparent window material operable at temperatures above 2000.degree. C., and which material possesses high tensile strength, is resistant to .erosion as well as particle impact at such temperatures, and is highly machinable. The method comprises: blending a powder mixture of 20-60% by weight silicon nitride, 12-40% boron nitride, 15-40% boron nitride, 15-40% silica, and 1-20% oxygen carrying sintering aids; (b) molding the mixture to shape as a preform; and (c) densifying the shaped preform into a monolithic window having high temperature stability and transparency at high temperatures.

Abstract: An adhesive composition for joining carbon-carbon composites comprising a polymeric thermosetting polysilazane, a ceramic powder, silicon powder, and carbon powder. The invention also comprises the method of making carbon-carbon composite structures utilizing such adhesive composition and to the resultant products.

Abstract: An adhesive composition for joining carbon--carbon composites comprising a polymeric thermosetting polysilazane, a ceramic powder, silicon powder, and carbon powder. The invention also comprises the method of making carbon--carbon composite structures utilizing such adhesive composition and to the resultant products.

Abstract: Coolant passages (14) of non-machinable size and shape are formed in a ceramic body (10) by individually forming sections (16) of the body (10), embedding graphite (20) therein during preforming, assembling the sections (16) into a complete preform (11), integrating the preform (24) by densifying it in an inert atmosphere under heat and pressure, and then heating the densified preform (10) in air to vaporize the graphite (19,20). In another aspect of the invention, a ceramic body (32) is formed from a three-dimensional, filled-in weave of silica fibers (30) in which the fibers (34) extending in one of the three dimensions are graphite and are subsequently vaporized.

Abstract: A method of forming a sodium sulfur battery and of starting the reactive capability of that battery when heated to a temperature suitable for battery operation is disclosed.An anodic reaction zone is constructed in a manner that sodium is hermetically sealed therein, part of the hermetic seal including fusible material which closes up openings through the container of the anodic reaction zone. The hermetically sealed anodic reaction zone is assembled under normal atmospheric conditions with a suitable cathodic reaction zone and a cation-permeable barrier. When the entire battery is heated to an operational temperature, the fusible material of the hermetically sealed anodic reaction zone is fused, thereby allowing molten sodium to flow from the anodic reaction zone into reactive engagement with the cation-permeable barrier.