Recent developments in ALON and spinel transparencies at Surmet

ALON^® Transparent Ceramic (ALON) consists primarily of aluminum and oxygen, similar to that of alumina, with a small amount of nitrogen added to help stabilize its cubic phase. Importantly, materials with cubic symmetry are optically isotropic, and consequently, transparent in their polycrystalline form. This allows ALON to be manufactured by conventional powder processing methods. Surmet has implemented an extremely robust manufacturing process for ALON optics blanks in very large flat as well as curved shapes. Spinel (MgAl₂O₄) is a cubic material, that transmits further into the infrared than ALON. Spinel is also produced via powder processing techniques similar to those used to produce ALON. Spinel’s superior transmission at wavelengths beyond 4.5um, make it the preferred option for certain MWIR sensor applications. ALON’s superior physical and mechanical properties combined with its superior producibility/manufacturability make it the material of choice for most other applications, including very large sensor windows and transparent armor. Powder processing provides the flexibility to produce both ALON and spinel components in a wide range of shapes and sizes, including complex dome shapes, such as hyper-hemispherical and tangent ogive, as well as conformal shapes for aerospace and automotive applications. To this end, Surmet has developed inspection polishing techniques applicable to conformal optics and curved transparent armor. Examples of inspection polished windows with complex curvature will be presented. Surmet has consolidated its manufacturing operations for large ALON and Spinel windows into our 75,000 square foot facility in Buffalo NY. The facility now houses new production furnaces and custom-built ceramics processing equipment that is the largest of its kind in the US. This expansion has established a vertically integrated capability to manufacture transparent ceramic products at this facility.