The bulk powder behavior of each type of silica particle and
mica powder before and after the removal of surface-adhered
nanoparticles by ultrasonic cleaning was investigated by a
friction tester and texture analyzer. The following conclusions
were drawn:
1) By the removal of surface-adhered nanoparticles after
ultrasonic cleaning, the CDF value of both the types of
silica particles decreased.
2) By the removal of surface-adhered nanoparticles after
ultrasonic cleaning, the AS value of porous silica did not
exhibit a substantial change; on the other hand, nonporous
silica did exhibit an increase in the AS value.
3) Surface-adhered nanoparticles of the substrate filler were
tentatively removed by ultrasonic cleaning, which resulted in
completely different properties even for the bulk forms.
4) Both the friction coefficient and AS value were consistently
influenced by the existence of nanoparticles for porous and
nonporous silica.