Ceramics-Silikáty 58 (3) 223-226 (2014)

Synthesis of aluminum oxynitride spinel powders by aluminothermic reaction under reducing conditions

Aluminum oxynitride spinel (AlON) powders were synthesized by aluminothermic reaction under reducing conditions provided by N₂–CO atmosphere using low cost and easily available aluminum and γ-Al₂O₃ alumina micron-sized powders as starting materials. The influence of Al/γ-Al₂O₃ ratio and sintering temperature on the phase composition and microstructure of sintered samples was explored. The experimental results showed that when Al/γ-Al₂O₃ mass ratio equal to 3, AlON phase with AlN as a minor phase can be formed at 1600°C using this method. And we attributed the presence of small amounts of AlN to the displacement of oxygen atoms from AlON phases by nitrogen atoms at high temperature under carbon embedded condition. At the same time, grains of AlON were tabular in shape and whiskers can be found in samples after sintered at 1600°C because of elevated amount o non-stoichiometric species (Al, Al₂O, AlO) produced in strongly reducing atmosphere.

Keywords: X-ray diffraction; ceramic; sintering; AlON