Effect of Heat on Hollow Multiphase Ceramic Microspheres Prepared by Self-Reactive Quenching Technology

Abstract

The self-reactive quenching technology, which combines flame thermal spraying technology, self-propagating high-temperature synthesis (SHS), and rapid solidification, is a new method for preparation of hollow microspheres. Based on this, the effect of heat released by different exothermic systems on preparation of hollow ceramic microspheres was studied. The results show that for low-exothermic system Si-Sucrose-NH4Cl, the self-propagating reactions cannot occur, and the quenching products are Si microspheres with porous structure. For the moderate exothermic system Al–SiO2-Sucrose, the quenching products consist of some grains, which are hollow spherical or nearly spherical particles and irregular powders. Formation of Al2O3–Si indicates possible occurrence of SHS reactions. Meanwhile, for high-exothermic system Al–Cr2O3-Sucrose-Si-Epoxy Resin, the quenching products consist of internal hollow spherical grains and irregular-shaped porous particles; the phase composition mainly contains Al2O3, Cr3C2, Cr7C3, Cr3Si, and mullite, showing completeness of SHS reactions. The higher the adiabatic combustion temperature of the system is, the more heat it releases is higher, and the ceramic droplets form easilier.