AlN evaporation in high temperature and growth of the AlN whiskers

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 (≤φ500 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.