A molecular dynamics study of sintering of micro injection moulded alumina nano particles

In this study, a comprehensive molecular dynamics (MD) study on the structural evolution of alumina nanoparticles during sintering has been performed using two-sphere model. The effect of variation in particle size and heating rate are investigated. A power-law equation is proposed to explain the increase of dimensionless neck radius, with the increasing sintering time. Two important parameters are extracted from the equation: a characteristic time related to the initiation of neck formation and an exponent related to the rate of neck growth. The variation of shrinkage and density of particles are also used to characterise the sintering of alumina nanoparticles. One of the novel findings is that instead of temporal variation of dimensionless neck radius, its variation with shrinkage can be used to correlate simulation and experimental results. From the results of the variation of heating rate, it is revealed that a lower heating rate initiates neck formation at a lower temperature. The sintering temperature has been successfully estimated for micron-sized particles from the results of molecular dynamics simulation using Herring's scaling law. Moreover, it is evident from experimental validation that the developed MD model can successfully predict the average dimensionless neck size value of micro injection moulded alumina, at sintered state, and thereby can be effectively used as a process control tool.