Studies on preparation of ceramic inks and simulation of drop formation and spread in direct ceramic inkjet printing

Recently, there is an increased interest to use ceramic containing inks to develop ceramic components for several strategic applications to develop sensors and fuel cells by depositing ceramic inks using direct ceramic inkjet printing technology (DCIJP), a free form fabrication process. In this paper, studies were made on the preparation of ceramic inks with (a) alumina powder in ethyl alcohol and (b) zirconia powder in ethyl alcohol at different volume fractions of ceramic and a dispersant. To understand the mechanism of drop formation, ejection, spread and flow of ceramic inks in microchannels, simulation studies were carried out using a software, CFD-ACE+. Different amounts (0.75-3 vol%) of an organic dispersant (oleic acid) were added to ceramic ink containing 5% of ceramic by volume in ethyl alcohol. The sediment packing densities (ϕm) of the resulting suspensions were calculated 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% of dispersant by volume was used for 5% alumina content. For 5% zirconia content, 2% of dispersant by volume gave a similar result. Experiments were also conducted to find the value of ϕm for different solid loadings (5-25 vol%) of ceramic with 1% dispersant. It is observed that the sediment packing density and the apparent viscosities are increasing when solid loading concentrations are increased for both inks. These results will be useful while designing a delivery system for DCIJP to handle different ceramic inks.