Synthesis and Rheological Experimental Study of Forsterite Aggregates

Dense single-mineral or polymineral aggregates with low porosity, small grain sizes, and no preferred fabric are ideal samples for rheological experiments at high pressure and temperature to investigate the deformation mechanisms and flow laws of minerals and rocks in the Earth’s crust and mantle. Preparing such samples is crucial for obtaining accurate rheological data. In this paper, we introduce an improved method for obtaining good rheological samples for rheological experiments using forsterite as an example. On the basis of previous work, high-purity nanopowders (SiO2 and Mg(OH)2) were used as starting materials, and forsterite aggregates were sintered at high temperature under vacuum condition. The forsterite aggregates were prepared in a cylindrical shape before sintering using a specially designed three-split mold. Scanning electron microscopy and Raman spectroscopy analyses indicated that the synthesized samples were composed of high-purity forsterite with a density of ~3.1 g/cm3 and a small grain size of ~1 μm. Rheological experiments on the synthesized forsterite aggregates showed comparable rheological strengths and parameters to those reported in previous studies, indicating that the forsterite aggregates synthesized by vacuum sintering technique are good for rheological experiments. Compared with the traditional hot-pressing technique of rheological sample preparation from sorted natural mineral powders, the vacuum sintering technique is much easier, greatly reducing the time and workload of sample preparation for rheological experiments. © 2024 Science Press. All rights reserved.