氮化铝高温下的挥发及其晶须生长

AlN EVAPORATION IN HIGH TEMPERATURE AND GROWTH OF THE AlN WHISKERS

采用无压烧结法制备氮化铝(AlN)块状陶瓷材料,在熟坯表面生成大量无色透明的纤维绒须状物。借助扫描电镜、能谱分析仪、X射线衍射及正交偏光显微镜等分析手段,对纤维绒须状物进行综合分析。结果表明:纤维绒须状物为AlN晶须,其形貌以四方柱为主,直径为1～20μm,长径比为250～1000。AlN晶须表面有纳米级球状AlN颗粒,粒径在500nm以下。将高纯AlN热压烧结后,对该烧结体进行的高温热重分析结果表明:1800℃下AlN烧结体开始明显挥发。分析认为:材料主要以AlN形式气化蒸发,表明AlN在高于1800℃有较大的蒸气压,晶须的生长机制为气固生长机制。

There are a large amount of fibers on the surface of AlN bulk materials prepared by no-press sintering. Results of SEM, EDS and XRD show that the morphology of fibers is tetragonal. The phase composition of fibers is AlN. The fibers are whiskers. The diameter of whiskers is 1-20 μrn and the ratio of length to diameter changed greatly from 250 to 1000. There are AlN sphere powders (&leφ500 nm) on the surface of AlN whiskers. High pure AlN bulk material by hot-pressed sintering begin to vaporize in the form of AlN molecule at 1800°C. Results show that AlN has larger vapor pressure. The growth mechanism of AlN whiskers is vapor-solid mechanism.