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

A new technology to fabricate low-to-zero shrinkage Al2O3-based compos ites, 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 oth er metals or ceramic phases to change the final composition, to enhanc e the mechanical properites, and to further compensate for the sinteri ng shrinkage, Interesting characteristics of this technology are easy green machining without binders, superior mechanical properties of rea ction-bonded bodies without final machining (also when green machined) , superplastic formability, near-net-shape capability, and broad micro structural and compositional versatility.