In the present study,electrostatic atomization(EA)behavior of several test liquids having much higher viscosities(1 400 mPa·s)than have previously been studied was investigated by spraying at a series of applied voltages and flow rates.The results showed that to obtain stable cone-jet mode spraying and hence gain better monodispersity of droplets,electrical conductivity,viscosity and surface tension of the liquid are important controlling factors.The stable cone-jet mode could be easily established for liquids having shear viscosities in the range from 80 to 1 400 mPa·s and surface tensions below 65 mN·m-1.In contrast,methylcellulose aqueous solutions with shear viscosities ranging from 10 to 540 mPa·s and moderate surface tensions(50~56 mN·m-1)generated more complicated spraying modes.However,fine TiO2 powder(a few micrometers in size)could be prepared using the EA method from its precursor solutions.
Titanium dioxide(TiO2) films were prepared by cone - jet mode electrospraying a titanium ethoxideprecursor solution onto a silicon substrate.The effects of spraying time,substrate temperature and aging on thesurface morphology of the films prepared were studied.Thin films obtained after spraying for 600 s were aged atroom temperature to form a porous TiO2 network with pores in the size range of 100 - 500 nm.Thicker filmswere prepared by spraying for 3 000 s,but these cracked on drying although it can be concluded that films pre-pared using a higher substrate temperature were denser.By this method,SiC coating was also prepared on anAl2O3 substrate using polysilane as a precursor.The result implies the potential of an industrial production ofdye sensitized solar cells by electrospraying technique.
