Milling of forsterite precursors and effect of milling medium on their chemical characteristics
Minagi Takushi; Shiono Takeshi; Nishida Toshihiko
Abstract:Forsterite (Mg2SiO4) precursor was synthesized from a heterogeneous alkoxide solution containing MgO powder with mean particle size of 100 nm. In order to improve the chemical characteristics of the precursor, a wet condition was adopted for milling. Effects of milling parameters and solvent on chemical characteristics of the precursor were studied. The mixture of ethanol and deionized water was used as a solvent. The water content was varied from 0 vol% to 100 vol%. The characteristics of the obtained precursors were evaluated by X-ray diffraction (XRD) method, differential thermal analysis (DTA), scanning electron microscope (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Milling in water was effective to lower the crystallization temperature of the precursor to forsterite. However, the milled precursor strongly aggregated. Calcined powder was locally sintered and a dense polycrystal could not be obtained. On the other hand, milling in a solvent containing ethanol modified the surface of the precursor with ethoxy group and, due to absorption of ethanol, this resulted in an effective relaxation of the aggregates and in easy handling of the powder. The solvent with 75 vol% water was the most effective among others for preparing monolithic forsterite powder which exhibits a good sinterability. Key Words:Forsterite, Precursor, Sol-gel, Milling, Mechanochemical effect, Aggregation, Crystallization, Sinterability