Milling of Forsterite Precursors and Effect of Milling Medium on Their Chemical Characteristics

摘要

Forsterite (Mg_2SiO_4) precursor wassynthesized from a heterogeneous alkoxide solution containingMgO powder with mean particle size of l00nm. In order toimprove the chemical characteristics of the precursor, a wetcondition was adopted for milling. Effects of millingparameters and solvent on chemical characteristics of theprecursor were studied. The mixture of ethanol and deionizedwater was used as a solvent. The water content was varied from0 vol percent to 100 vol percent. The characteristics of theobtained precursors were evaluated by X-ray diffraction (XRD)method, differential thermal analysis (DTA), scanning electronmicroscope (SEM) and Fourier transform infrared (FT-IR)spectroscopy. Milling in water was effective to lower thecrystallization temperature of the precursor to forsterite.However, the milled precursor strongly aggregated. Calcinedpowder was locally sintered and a dense polycrystal could notbe obtained. On the other hand, milling in a solvent containingethanol modified the surface of the precursor with ethoxy groupand, due to absorption of ethanol, this resulted in an effectiverelaxation of the aggregates and in easy handling of the powder.The solvent with 75 vo1 percent water was the most effectiveamong others for preparing monolithic forsterite powder whichexhibits a good sinterability