Seeding of the Reaction‐Bonded Aluminum Oxide Process

The effect of the initial α‐Al 2 O 3 particle size in the reaction‐bonded aluminum oxide (RBAO) process on the phase transformation of aluminum‐derived γ‐Al 2 O 3 to α‐Al 2 O 3 , and subsequently densification, was investigated. It has been demonstrated that if the initial α‐Al 2 O 3 particles are fine (∼0.2 μm, i.e., 2.9 × 10 14 γ‐Al 2 O 3 particles/cm 3 ), then they seed the phase transformation. The fine α‐Al 2 O 3 decreases the transformation temperature to ∼962°C and results in a finer microstructure. The smaller particle size of the seeded RBAO decreases the sintering temperature to as low as ∼1135°C. The results confirm that seeding can be utilized to improve phase transformations and densification and subsequently to tailor final microstructures in RBAO‐derived ceramics.