ZRCI Refractory Sheet Type RS-99-60 and RS-99-45 are comprised of 99% alumina. These "All-Alumina" materials are strong, uniform, rigid, refractory structure composed of alpha alumina fibers and high purity inorganic binders. Type RS-99-60 and RS-99-45 have a high purity alumina bond making them well suited for use in high vacuum and reducing environments where silica cannot be tolerated, such as power metal and MIM furnaces with H2 atmospheres. They also have high electrical resistivity at elevated temperatures allowing them to be used in direct contact with resistance heating elements. They exhibit superior hot strength and dimensional stability to 1650°C (3000°F). RS-99-60 has a density of 60 lbs/ft³ (1 gm/cc) and RS-99-45 has a density of 45 lbs/ft³ (.72 gm/cc). ZRCI Refractory Sheet low density fiber reinforced ceramic composites are available as boards, cylinders and custom shapes. They have a fine open pore structure, high porosity and low thermal conductivity. These materials are fabricated as true composite laminates. They can be constructed into near net complex shapes. They can also be machined to tight exacting tolerances with ordinary shop tools and equipment. Their superior machinability and dimensional stability plus low heat capacity make them ideal for use as setters, supports and process fixtures in both continuous and batch firing furnaces. They contain no organic binders and will not smoke or produce odors when heated. They show excellent resistance to chemical attack and are not affected by oil or water. They are, however, affected by hydrofluoric acid, phosphorous acid and strong alkalis.