Consolidation of Nanograin Ceramics

The proposed program will demonstrate the feasibility of consolidating nanoparticle dispersions of high purity yttria (Y2O3) to produce fine grain (< 1 µm) infrared transparent material for supersonic missile domes and windows. Previously funded efforts to produce IR transparent yttria resulted in material with high transmittance but insufficient strength to withstand the mechanical and thermal stresses imposed by the application conditions. Nano and small grain ceramics offer the potential for improved mechanical strength over their larger grain counterparts. CeraNova Corporation has developed techniques for shaping and densifying nanoparticle alumina to produce transparent polycrystalline alumina with grain size 400-700 nm, excellent transmittance in the MWIR (3-5µm), and mechanical properties superior to sapphire. These techniques, and previous experience gained from earlier work on transparent yttria, will be applied to the proposed program, which will utilize dispersions of yttria-based nanoparticulates supplied by a nano-powder provider. CeraNova's proposed approach involves shape-forming and consolidation of particle dispersions and a two-stage densification process to achieve full density and control grain growth. The objective is to achieve transmittance ~80% in the 3-5µm region for 2mm thick disks and mechanical strength twice as great as that of the conventional, large grain equivalent.