A comparative study on nano La2O3 suspension treated by ultrasonic and ball milling

This paper presented a scientific study of the effects of four dispersion methods on the dispersion capability of nano La₂O₃ suspensions, which are ball milling, ultrasonic, ultrasonic followed by ball milling and ball milling followed by ultrasonic. For the purposes of comparing their dispersion capability, sedimentation test, Zeta-potential measurement test, particles size measurement test and transmission electron microscopy (TEM) test were carried out. Suspension ability coefficient was also defined with expectation to estimate the stability of nano La₂O₃ suspension through granularity size, and their relationship curve was worked out. The results showed that ultrasonic followed by ball milling enjoyed an excellent capability of dispersion for nano La₂O₃ suspension. Its mechanism was discussed, and breakage models of nano La₂O₃ particles were developed. The study results indicated that ultrasonic followed by ball milling could break through both the limits of ultrasonic dispersion size range and thermo-effect, and thus was able to overcome the problem of the secondary aggregation of nanoparticles. Moreover, aggregations could be further de-agglomerated. As a result, dispersion capability of nano La₂O₃ suspension could be improved more greatly by ultrasonic followed by ball milling. And its suspension stability was the best with the highest suspension ability coefficient of the nanoparticles. It was found in the experiment that there was almost no obvious phenomenon of stratification for the suspension with a little sediment after being deposited for 8 d.