abstract
Spherical granules of aluminum nitride (AlN) with an average particle size of about 50m were produced from aqueous suspensions using an AlN powder surface treated against hydrolysis with aluminum dihydrogenphosphate [Al(H2PO4)3]. Two different amounts of Al(H2PO4)3 were tested and the effects of surface treatment and aging time were evaluated by various techniques (XRD, TG-DTA, zeta potential and pH measurements). The treated powder exhibited antihydrolytic property and good dispersing behavior, enabling the preparation of low-viscosity and high-concentration aqueous AlN slurries for freeze granulation. The spherical AlN granules were sintered in a boron nitride (BN) powder bed followed by ultrasonic washing of the AlN granulates/BN mixture to remove BN. The sintered spherical AlN granules present excellent crystallinity and high sphericity as observed from SEM micrographs.
keywords
ALUMINUM NITRIDE POWDER; GAS-REDUCTION-NITRIDATION; THERMAL-CONDUCTIVITY; CERAMICS; PARTICLES; PHOSPHATE; DEGRADATION; GRANULATION; SUSPENSIONS; PROTECTION
subject category
Materials Science
authors
Wang, Q; Olhero, SM; Ferreira, JMF; Cui, W; Chen, KX; Xie, ZP
our authors
José Maria da Fonte Ferreira
Retired Professor
Susana Maria Henriques Olhero
Assistant ProfessorProjects
Development of microelectromechanical systems by gelcasting - GELMEMS (PTDC/CTM/099489/2008)
acknowledgements
Q. Wang thanks the financial support of National High Technology Research and Development Program of China (863 program, 2009AA03Z211). S. M. Olhero wishes to thank Foundation for Science and Technology of Portugal for the financial support under the grant SFRH/BPD/27013/2006. The authors would also like to thank CICECO for the work at the University of Aveiro and FCT for the financial support under the project PTDC/CTM/099489/2008.