Reactive molecular dynamics analysis of alumina nano-powders under warm compaction process

In this paper, the warm compaction process of alumina ceramic nano-powders is investigated through the molecular dynamics method, emphasizing the impact of nanoparticle size, heating temperature, and confining pressure on the final green product. The study unravels the complexities of the alumina compaction process with a focus on alpha-alumina (α-Al₂O₃) based on the reactive force field (ReaxFF). Three distinct stages are performed through the MD analysis of the warm compaction process, i.e. relaxing the nano-powders, increasing the pressure and temperature, and decreasing them to the room conditions. The nano-powders are generated with various sizes of nanoparticles to facilitate a comprehensive exploration of size effect on the compaction behavior. The accuracy of the proposed computational model is verified by comparing the results of the alumina nano-powder warm compaction process with those of experimental data. The optimal hold time is determined for the peak density in the MD analysis of the warm compaction process. The results highlight a nonlinear behavior of heating temperature and pressure on the relative density of the final green product, such that the temperature influence significantly reduces by increasing the pressure. Moreover, the size of nanoparticles is investigated during the warm compaction process of alumina nano-powders; it is shown that the relative density and energy density of the final green product increase by decreasing the size of nanoparticles.