Simulation study on the melting process of nano-corundum

When the shape of α-Al2O3 product is very complicated, 3D printing technology based on laser or ion beam energy would be the best choice. But it is very difficult at present because of the high melting point and low thermal conductivity of α-Al2O3. So studying the melting process of nano α-Al2O3 with the different particle size can help to provide a guidance for 3D printing of α-Al2O3. In this paper, the melting point and melting process of nanosized α-Al2O3 with the radius of 1-2.2 nm were studied by molecular dynamics simulation. Results showed that: The melting points of nano-particles increased along with the radii increased. The melting point of 1.8 nm particle was 2200 K. Its melting process could be divided into four stages: the thermal expansion stage 300-700 K, the surface activation stage 700-1600 K, the pre-melting stage 1600-2200 K, and the melting stage 2200 K. Dominantly due to the migration of O atoms during the melting process, the bond broke at the sites 2.55 Å (1 nm = 10 Å), etc. away from the central atom. The heating rate had a great influence on the melting process of α-Al2O3 nanoparticles. The higher the heating rate, the higher the melting point. The nanoparticle could be superheated and the superheating phenomenon had the dynamic stability limit temperature.