Phase, microstructure and sintering of aluminum nitride powder by the carbothermal reduction-nitridation process with Y 2O 3 addition

摘要

AbstractAluminum nitride powders were synthesized by carbothermal reduction-nitridation method using Al(OH)3, carbon black and Y2O3as raw materials. The change of phase, microstructure and densification during the AlN synthesis and sintering process were investigated and the effects of Y2O3was discussed. The results showed that Y2O3reacted with Al2O3to form yttrium aluminates of YAlO3(orthorhombic and hexagonal phases), Y4Al2O9and Y3Al5O12at the low temperature of 1350°C. YAlO3could firstly be transformed into Y2O3and then completely into YN when the firing temperature and holding time increased. However, YN could be oxidized into Y2O3again after the carbon removal at 700°C in the air atmosphere. There were two ways generating AlN when adding Y2O3and the possible mechanism was proposed. Y2O3from YN oxidation favored the densification of AlN ceramics because the liquid had better flowability and distribution in the sintering process at 1800°C.]]>