氮化铝粉末特性对氮化铝-氮化硼复合陶瓷结构和性能的影响

EFFECT OF ALUMINUM NITRIDE POWDER CHARACTERISTICS ON MICROSTRUCTURE AND PROPERTIES OF ALUMINUM NITRIDE-BORON NITRIDE COMPOSITE CERAMICS

以比表面积为4.26m2/g、氧含量(质量分数,下同)为0.98%和比表面积为17.4m2/g、氧含量为1.69%的2种AlN粉末为原料,用无压烧结工艺制备氮化铝-氮化硼(AlN-15BN,BN为15%)复合陶瓷,研究了AlN粉末对复合陶瓷显微结构和性能的影响。结果表明:AlN粉末对复合陶瓷的致密化过程以及陶瓷的性能有重要影响。由于高比表面积AlN粉末的烧结活性好,AlN-15BN复合陶瓷的烧结致密化温度主要集中在1500～1650℃之间。在1650℃烧结3h后,AlN-15BN复合陶瓷的相对密度可达95.6%,热导率为108.4W/(m.K),硬度HRA为72。继续升高烧结温度,AlN-15BN复合陶瓷的致密度变化不大,热导率升高,硬度下降。在1850℃烧结后,AlN-15BN复合陶瓷的热导率为132.6W/(m.K),Rockwell硬度(HRA)为64.2。低比表面积的AlN粉末所制备的AlN-15BN复合陶瓷的致密化过程主要发生在1650～1800℃间。在1850℃烧结3h,制备出AlN-15BN复合陶瓷的相对密度为86.4%,热导率为104.2W/(m.K),HRA为56.2。

Two different kinds of aluminum nitride （AIN） powders with specific surface areas of 4.26 m^2/g and 17.4 m^2/g and oxygen contents of 0.98% （in mass, the same below） and 1.69% were used to prepared aluminum nitride-boron nitride （AIN-15BN, content of BN is 15% in mass） composite ceramics. The effect of AIN powder characteristics on the microstructure and properties of A1N-15BN composites were studied. It was found that the characteristics of AIN powder have a great influence on the densification and properties of AIN-15BN ceramics. The densification temperature of composite ceramics with AIN powders synthesized from the combustion precursor was at 1 500-1 650 ℃. The AIN-15BN ceramics with relative density 95.6% and Rockwell hardness HeA=72 were obtained after sintering at 1 650 ℃for 3 h. The density of this composite did not increase with the continual increase of sintering temperature. However, the thermal conductivity was increased with the increasing of sintefing temperature and could reach 132.6 W/（m·K） when sintered at 1 850℃, but the hardness was reversed to HRA=64.2. For AIN-15BN ceramics prepared with powders synthesized from the precipitated precursor, the densification temperature was in the range of 1 650-1 800 ℃. The AIN-15BN ceramics with relative density 86.4%, thermal conductivity 104.2 W/（m.K） and HRA=562 was obtained after sintering at 1850 ℃ for 3 h.