No 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-NH 4 Cl, the self-propagating reactions cannot occur, and the quenching products are Si microspheres with porous structure. For the moderate exothermic system Al-SiO 2 -Sucrose, the quenching products consist of some grains, which are hollow spherical or nearly spherical particles and irregular powders. Formation of Al 2 O 3 -Si indicates possible occurrence of SHS reactions. Meanwhile, for high-exothermic system Al-Cr 2 O 3 -Sucrose-Si-Epoxy Resin, the quenching products consist of internal hollow spherical grains and irregular-shaped porous particles; the phase composition mainly contains Al 2 O 3 , Cr 3 C 2 , Cr 7 C 3 , Cr 3 Si, 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.

In order to improve the preparation technology of hollow ceramic microspheres, hollow ceramic microspheres were prepared by self-reactive flame quenching technology based on the main system of Al + Cr 2 O 3 . The results show that: the products are composed of two types of particles which are ball and irregular powders. The size of the ball particles is between 40-60 m, and most of the ball particles have hollow structure inside. So the wanted hollow ceramic microspheres can be prepared by self-reactive flame quenching technology based on the main system of Al + Cr 2 O 3 .