Seeding of the reaction-bonded aluminum oxide process

The effect of the initial alpha -Al2O3 particle size in the reaction-bonded aluminum oxide (RBAO) process on the phase transformation of aluminum-deri ved gamma -Al2O3 to alpha -Al2O3, and subsequently densification, was inves tigated. It has been demonstrated that if the initial alpha -Al2O3 particle s are fine (similar to0.2 mum, i.e., 2.9 x 10(14) gamma -Al2O3 particles/cm (3)), then they seed the phase transformation. The fine alpha -Al2O3 decrea ses the transformation temperature to similar to 962 degreesC and results i n a finer microstructure. The smaller particle size of the seeded RBAO decr eases the sintering temperature to as low as similar to 1135 degreesC, The results confirm that seeding can be utilized to improve phase transformatio ns and densification and subsequently to tailor final microstructures in RB AO-delived ceramics.