Cellular growth of 2M-wollastonite in flux growth process relevant to preparation of high aspect ratio particles

High aspect ratio 2M-wollastonite particles were prepared using a flux growth process, in which a unidirectional temperature gradient was established in the melt. The one-dimensional heat transfer caused the crystals to display clear cellular structure. The measured cellular growth rate decreased from similar to 12 to 8 mu m s(-1) within 20 min of crystallisation time. However, the primary arm spacing remained nearly constant at similar to 7.5 mu m. B2O3 can significantly lower the melting point of the mixture, which made the handling of the molten silicate mixtures easier. The cellular/dendritic structures were maintained up to a maximum B2O3 content of 20 wt-%. The primary arm spacing increased from 8 mu m at 8 wt-% B2O3 to similar to 40 mu m at 20 wt-% B2O3. The corresponding mean aspect ratio of 2M-wollastonite particles decreased from similar to 12:1 (a high aspect ratio grade) at 8 wt-% B2O3 to similar to 4:1 (a low aspect ratio grade) at 20 wt-% B2O3.