Ultrasonic cavitation at solid surfaces.

In spite of the great potential of applying high-intensity ultrasound, which enables high-temperature and high-pressure chemistry with a reactor near room temperature and ambient pressure, sonochemistry at solid surfaces is at a weak stage of understanding with regards to the development of new materials and composite nanostructures. The science towards a quantitative understanding is only now emerging. On the other hand, in many applications an ultrasonic bath is used without thinking of the mechanism. Often surfaces are exposed to ultrasound for cleaning. Since ultrasonic treatment is not an exotic process and applicable even on large scale in industrial manufacturing, controlling the process may lead to new applications making use of the specially designed surface. This review is intended to summarize recent progress in this field and to point out most promising directions of ultrasound application for the development of new materials with functional surfaces.