In situ observations of isothermal cuspidine crystallization in molten mould fluxes with varying basicity

Cuspidine is an important crystallization product in CaO–SiO₂–CaF₂ based mould flux. A deeper understanding of cuspidine crystallization behaviour is significant to obtain superior heat transfer and lubricative properties. Cuspidine crystallization was observed in situ using a confocal scanning laser microscopy. The results shown that cuspidine typically shows different dendritic morphologies in molten fluxes. The morphology transforms from long equiaxed dendrites, partially equiaxed dendrites and small block shape containing dendrites concurrence to regular blocky shapes containing dendrites as the isothermal temperature decreases from 1150°C to 1000°C for a flux with R = 1.1. Cuspidine morphology changes from robust dendrites, partially dendrites and small block shapes containing dendrites concurrence to blocky shapes containing dendrites as the isothermal temperature decreases from 1250°C to 1150°C for a flux with R = 1.2. The effects of temperature and basicity on the morphology transition and growth of cuspidine were analysed.