REACTION BONDING OF ALUMINUM-OXIDE (RBAO) - SCIENCE AND TECHNOLOGY

A new technology to fabricate low-to-zero shrinkage Al2O3-based composites, Reaction Bonding of Aluminum Oxide (RBAO), is presented: Al and Al2O3 precursor powder mixtures are intensively milled, compacted, and heat-treated in air, such that Al fully oxidizes to Al2O3. The volume expansion associated with the oxidation partially compensates for the sintering shrinkage. The process can be modified by incorporating other metals or ceramic phases to change the final composition, to enhance the mechanical properites, and to further compensate for the sintering shrinkage, Interesting characteristics of this technology are easy green machining without binders, superior mechanical properties of reaction-bonded bodies without final machining (also when green machined), superplastic formability, near-net-shape capability, and broad microstructural and compositional versatility.