ZIRCAR Ceramics’ Aumina Type CRYSTAL-18 insulating boards, cylinders and custom shapes are vacuum-formed combinations of polycrystalline (PCW) alumina fiber, high-purity Refractory Ceramic Fiber (RCF) and refractory binders. CRYSTAL-18 exhibits low thermal conductivity, good strength, superior thermal shock resistance and high dimensional stability in applications with continuous temperatures to 1550°C (2822°F).
CRYSTAL-18A is dried and contains a few wt% organic binder. CRYSTAL-18B has been prefired and is organic-free.
CRYSTAL-18 exhibits an open-pore structure which readily accepts surface rigidizations or coating with ceramic adhesives. Such surface treatments enhance CRYSTAL-18’s strength and handleability for use in MoSi2 Heating Element Assemblies and other advanced systems.
CRYSTAL-18 shows excellent resistance to chemical attack and is not affected by oil or water. It is, however, affected by hydrofluoric acid, phosphoric acid and strong alkalis.