International audienceFilament growth and breakup are investigated in the context of ceramic inkjet printing. Several inks were formulated and ejected on a printer dedicated to ceramic materials. They consisted of six colloidal inks, four simple fluids and two graphic inks. For each, stroboscopic snapshots were acquired and the filament shape was extracted and analysed, for different nozzle actuation pulses. The filament length and the thread minimum radius were measured during the ejection process. A scaling of the breakup time with the Rayleigh number was obtained, as well as a general behaviour for the filament growth rate during the ejection process
International audienceBaTiO3-based materials are currently used for the fabrication of multilayer ceramic capacitors (MLCC) because of their high dielectric properties. The inkjet printing (IJP) process can be used to fabricate MLCC of complex configurations by integrating internal electrodes and dielectric layers in a single step using a multi printing-head system. Stabilized aqueous suspensions of BaTiO3-based powders are required to obtain dielectric inks adapted to IJP. This study investigates the influence of BaTiO3 powder hydrolysis in water on the surface chemistry and stability in relationship with the milling step used to adjust the powder grain size to IJP. Optimum parameters for a good stability of BaTiO3 suspensions are identified. The selected dispersant is a polyacrylate (PAA) for which the content is adjusted to minimize the sedimentation rates as required by IJP. Moreover, the addition of ethylene glycol is shown to be necessary to avoid the formation of a gel structure which could result from the interaction of borates ions leached from the surface of BaTiO3 with the PAA dispersant. A mechanism of gel formation is proposed
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