Abstract: Furnace assemblies are provided including a furnace defining an internal process chamber extending therethrough. A first gas screen is coupled to the furnace. The first gas screen is configured to introduce a first gas into the internal process chamber at a first end of the furnace. A second gas screen is positioned adjacent to the first gas screen at an opposite end of the first gas screen from the furnace. The second gas screen is configured to introduce a second gas to provide a seal for the first end of the furnace. The furnace may be a draw furnace and the process chamber may be an internal draw chamber.

Abstract: A preferred embodiment of a sulfide glass with improved mechanical and optical properties such as extended transmission in the infrared region of radiation having wavelengths of up to about 15 microns, Tg in the range of 370.degree.-550.degree. C., and thermal stability of 100.degree.-300.degree. C., containing, on mol basis, 36-72% germanium sulfide, 2-38% gallium sulfide and/or indium sulfide, and 26-62% of at least one modifier containing an alkaline earth sulfide. A process for making glass of improved mechanical and optical properties comprises the steps of mixing glass components, including an alkaline earth modifier in elemental or sulfide form; melting the glass components in an inert vessel contained in a sealed ampoule to form a molten mixture; cooling the molten glass mixture to a solid state; annealing the solid glass; and cooling the annealed glass to about room temperature.

Abstract: A sulfide glass with improved mechanical and optical properties such as ended transmission in the infrared region of radiation having wavelengths of up to about 15 microns; Tg in the region of 410.degree.-550.degree. C.; and thermal stability of 100.degree.-300.degree. C. based on the difference between T.sub.g and T.sub.x, comprising, on mol basis, 20-90% germanium sulfide, 0-60% gallium sulfide, and 5-60% of at least one modifier in sulfide form. A process for improving mechanical and optical properties of a sulfide glass based on gallium sulfide and/or germanium sulfide comprises the steps of mixing glass components, including a modifier in elemental or sulfide form; melting the glass components to form a molten mixture; cooling the molten glass mixture to a solid state; annealing the solid glass; and cooling the annealed glass to about room temperature.

Abstract: A germanate glass ceramic article which has better thermal and physical perties than the competing materials of zinc sulfide, spinel, and sapphire is made by mixing germanate ceramic glass components; melting the components to form a molten mass; cooling the molten mass to form a solid glass article; nucleating the solid article by heating it in the range of about 630.degree.-790.degree. C. for about 1-16 hours to develop nuclei in the article; and crystallizing the nucleated article by heating it, after nucleation, in the range of about 1/2 minute to about 8 hours to grow the nuclei to crystallites having an average diameter of less then about 1000 nanometer (nm); and cooling to form the glass ceramic.