One-time mass production of AlN nanosheets: Synergistic effect of high-energy shear and effective collision in a sanding mill

Abstract

Aluminum nitride (AlN) has attracted huge attention in new energy vehicle, communication equipment fields, due to the high-thermal conductivity and reliable insulating ability. One of the most crucial factors is the preparation of high-performance AlN powders, and more significantly, the two-dimensional nanostructure would change the phonon vibration mode and transport process, bringing in the novel heat conduction and electricity properties. In this paper, kilogram of two-dimensional aluminum nitride nanosheets (AlNNS) with thicknesses around 30 nm and particle sizes around 400 nm were prepared by a new strategy for the nano sanding process, in which they still keep high purity (impurity content ppm grade) without further purification. Furthermore, the technological parameters of the sanding time and line speed are found as the key factors, that would affect the transformation process from hexagonal AlN into super-thin AlNNS. The morphology of the nanosheets is more complete at the line speed of 8 m/s. In addition, AlNNS have an increase of 7% in thermal conductivity (at 50 °C) compared to that of raw powders. Moreover, AlNNS have stronger sintering activity due to the larger specific surface area, in which show an increase of 16.8% in shrinkage. Therefore, AlNNS would represent excellent physical properties more than thermal conductivity, providing a new dimension research in high-thermal conductivity ceramics. Last but not least, nano sanding strategy as a purely physical process, avoids the subsequent chemical purification process, and has the advantages of simple and efficient, low energy consumption and environmental protection.