Synthesis and sintering of nano-sized forsterite prepared by short mechanochemical activation process

The findings reported in this paper offer an affordable technique for the synthesis of nano-sized pure forsterite from magnesium chloride hexahydrate, sodium metasilicate nonahydrate and sodium hydroxide as precursors. The stoichiometric mixture of reagents was manually mixed and subjected to high-energy ball milling for a short time (∼10 min). The monitoring of as-milled powder by x-ray diffraction method confirmed that the solid-state displacement reactions occur during high-energy ball milling. After washing and drying, the resulting precursor was subjected to heat treatments in air at various temperatures ranging from 500 to 1100 °C for studying forsterite development. The heat-treated powders were characterized by XRD, STA, FTIR, BET, FE-SEM and TEM techniques. The results revealed that the hydrated compounds formed at room-temperature completely dissociate into periclase and forsterite from 600 °C. The more forsterite phase was generated by the increase of temperature from 600 to 800 °C by the consumption of periclase and amorphous silica present in precursor and finally single-phase forsterite was yielded at 900 °C/2 h. The TEM and FE-SEM results demonstrated that the as-prepared powder consists of separate particles with nearly spherical morphology, 20-60 nm mean particle size and 15.4 m2/g specific surface area. Sample sintered at 1500 °C/2 h had 89.5% theoretical density and homogeneous single-phase microstructure.