Spinel Reconnaissance Window

Spinels combination of extended MWIR transmission and its ability to be produced in large sizes using conventional powder processing techniques, make it the material of choice for many sensor window applications. However, the severe environmental requirements for these applications drive the spinel windows strength requirements well beyond that has been demonstrated using the LiF hot pressing/HIP process. This is the most common method for producing large plates of spinel. By contrast, Surmets spinel is produced by a sinter/HIP process, which has long been known to provide much stronger spinel than hot pressing. During the Phase I effort, Surmet produced spinel blanks of up to 6x10x0.6 using its solid state sinter/HIP process. Biaxial flexure strength testing showed that Surmets spinel was significantly stronger (225-245MPa) than the spinel produced by LiF hot pressed/HIP (~100 MPa). The overall objective of the Phase II is to manufacture large spinel windows that meet the strength and optical requirements. Threshold set for part size is at 19x27x0.6, with objective at 30x28x0.6. This effort would leverage Surmets considerable expertise in commercially producing large ALON blanks up to 19x36 size and its very large furnace capabilities to demonstrate commercial production capability for large spinel windows.