Influence of AIN powder characteristic on densif icationof AlN-BN composite ceramics

AlN-15BN (mass f raction , %) composite ceramics were fabricated with two different kinds of AlN powders with specific surface areas of 4. 26 m² / g and a 17. 4 m² / g , respectively , and 5 %Y₂O₃ as sintering additives.The effect s of the specific surface area of AlN powders on the densification of AlN-BN composite ceramics werestudied. The result s show that the specific surface area of AlN powders has great influence on the densificationprocess of composite ceramics. The densification temperature of composite ceramics is at 1500～1650 ℃with highspecific surface area AlN powder , and AlN-BN ceramics with relative density 95. 6 % was obtained af ter sintering at1650 ℃for 3 h. The density of this composite does not increase with the further increasing of sintering temperature.For AlN-BN ceramics prepared with low specific surface area AlN powders , the densification temperature is in therange of 1600～1850 ℃, and AlN-BN ceramics with relative density 86. 4 % was obtained af ter sintering at 1850 ℃for3 h. The high specific surface area of AlN powders can enhance the densification of AlN -BN composite ceramics.