Rheological Behaviour of Ceramic Inks for Direct Ceramic Inkjet Printing

Abstract

In this paper, studies were made on the preparation of ceramic inks with: (i) alumina powder
in ethyl alcohol and (ii) zirconia powder in ethyl alcohol at different volume fractions of ceramic.
Different amounts (0.75-3.00 vol %) of an organic dispersant (oleic acid) were added to ceramic
ink containing 5 per cent of ceramic by volume in ethyl alcohol. The viscosities of the suspensions
were determined with Brookefield viscometer (model: DV-E), which is suitable for measuring
the viscosities of suspensions accurately. These inks were deposited on a substrate to see their
spread. The sediment packing densities ( m) of the resulting suspensions were calculated using
theoretical models which can be related to the density that can be achieved in the final product.
The highest sediment packing density was arrived at low viscosity values of the ink and occurred
when 1 per cent of dispersant by volume was used for 5 per cent alumina content. For 5 per
cent zirconia content, 2 per cent of dispersant by volume gave a similar result. Experiments
were also conducted to find the value of m for different solid loadings (5-25 vol %) of ceramic
with 1 per cent dispersant. It was observed that the sediment packing density and the apparent
viscosities were increasing when solid loading concentrations were increased for both alumina
and zirconia-based inks. The optimum value of m and viscosity have been determined from this
study. The results of this preliminary study will be useful for further investigations on the
rheological behaviour of ceramic inks for direct ceramic inkjet printing.