Low Cost Production of High Purity and Phase Pure Ultrafine Powders of MgAl2O4 Spinel

We propose to use a novel synthesis process to produce ultrafine (0.1 - 0.4 microns) and highly sinterable powders of MgAl2O4 spinel. The synthesis process, which utilizes nanoparticles as starting material, overcomes the limitations posed by conventionalpowder synthesis processes on the chemical purity as well as the phase purity of the spinel compound. Furthermore, since the powder production process is scalable and low cost, it will enable the ultimate objective of replacing sapphire with alternativepolycrystalline materials that perform as well as sapphire but at a fraction of the cost. Accordingly, as part of the Phase I work, we will produce test batches of ultrafine powders of MgAl2O4, and characterize the structure and composition. In particular,advanced characterization tools will be used to characterize the compositional homogeneity in the powders. Furthermore, the sinterability of the powders will be demonstrated by hot pressing under different conditions and evaluating the microstructuralevolution. MgAl2O4 spinel obtained from a commercial source will be used for purposes of comparison. The powder synthesis process demonstrated in Phase I will be scaled in Phase II with emphasis on reproducibility and cost. During the course of the PhaseII program, several batches of powders will be provided to Army contractors to fabricate test components and provide feedback in order to further optimize the powder production process. The goal under this program is to eventually become a supplier ofMgAl2O4 spinel powders for all of DoD needs. Transparent ceramics offer a number of different opportunities in both military and civilian applications, including infrared windows in heat seeking missiles and optical systems. The total market for suchcomponents is several tens of millions of dollars. A powder consolidation approach is an attractive low cost alternative to melt processing and vapor deposition processes that are used to produce single crystals. The dearth of ultrafine powders withexceptionally high compositional purity presents an opportunity. Accordingly, we propose to fill this market need using our synthesis process.