Abstract
Precipitation and ripening of an amorphous aluminogel in an aqueous solution were subjected to irradiation of ultrasound with various intensities and frequencies. For comparison with the ripening of aluminogel, hydration of amorphous alumina powder in the ultrasonic-driven water was studied. It was found that an intensive ultrasound during ripening decreased the relative amount of bayerite, whereas, a moderate ultrasound during ripening increased the relative amount of bayerite. On the other hand, the relative amount of bayerite increased with the increasing intensity of ultrasound when the gels were precipitated ultrasonically and ripened normally. The role of ultrasound in the ripening (dissolution-precipitation) process is discussed.
