Rheological Behaviour of Ceramic Inks for Direct Ceramic Inkjet Printing

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.