Synthesis and spark plasma sintering of the α-Si3N4 nanopowder

A two-step process (milling and then heat treatment) was used for the preparation of α-Si3N4 nanopowder. The influence of the milling time and heat treatment temperature as processing parameters were investigated on the formation of α-Si3N4. Silicon nitride ceramic was produced by spark plasma sintering at 1700 °C for 15 min, using MgSiN2 additive. The optimum sample was produced in a 30 h milling time, heat treatment at 1300 °C, and a 22 °C/min heating rate conditions. X-ray fluorescence analysis showed that the purity of the final product is above 98%. Nanoindentation hardness and Young's modulus of the SPS-ed sample were measured as 17±2.0 GPa and 290±11.0 GPa, respectively.