S02 セラミックスのソノプロセス : 強い超音波と弱い超音波の物理と化学(特別講演)

抄録

Ceramic processing, such as nanoparticles synthesis via precipitation, sol-gel method, electrochemical deposition, spray pyrolysis, metallurgy, and so forth, can be stimulated by physicochemical actions of ultrasound. In this presentation, various experimental works on sonoprocess of ceramic materials are divided into the following three categories and reviewed; (i) acceleration of a process/reaction that can proceed (slowly) in the absence of ultrasound, (ii) switching or induction of a process/reaction that does not proceed in the absence of ultrasound, and (iii) alteration/modification in the texture/microstructure of the product. In addition, quite a queer use of weak ultrasonication at a power of milliwatt is introduced. What I named soft sonication treatment significantly enhanced the aging of the starting solutions for precipitation. Experimental evidences were shown in the precipitation of oxalate precursor in ethanolic solution and the Stober synthesis of silica spheres. The author hypothesize that a microscopic inhomogeneity of solutes and solvents is influential upon nucleation, time-dependent for a duration of days, and enhanced by soft sonication.