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

Abstract

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 ∼12 to 8 μm s^− 1 within 20 min of crystallisation time. However, the primary arm spacing remained nearly constant at ∼7.5 μm. 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 μm at 8 wt-% B₂O₃ to ∼40 μm at 20 wt-% B₂O₃. The corresponding mean aspect ratio of 2M-wollastonite particles decreased from ∼12:1 (a high aspect ratio grade) at 8 wt-% B₂O₃ to ∼4:1 (a low aspect ratio grade) at 20 wt-% B₂O₃.

Keywords:

• Cellular
• Dendritic
• High aspect ratio
• Wollastonite
• Crystal growth