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Direct foaming of ceramic slurries - Targeted adjustment of foam properties and rheological aspects of quality controlWednesday (07.10.2020) 14:20 - 14:40 Room 1 Part of:
Direct foams can be created by physical-mechanical mixing of air and slurry. In most cases surfactants or so-called foaming agents are used to stabilize the wet foams. For the production of those foams different technologies can be applied. Some examples are the use of fast rotating mixers, rotor stator systems or a special oscillation process. An alternative kind of foam generator has been developed at IKTS with respect to the abrasive character of ceramic slurries. The slurry is pumped through a porous pipe while pressurized air is used to enable a stream of fine dispersed gas bubbles through the pipe into the slurry. Afterwards slurry and air bubbles were blended by a static mixer to form a homogenous foam.
Aim of this presentation is to show that this technology enables a continuous production of foams with an industrial relevant throughput. In dependence of the used components (porosity of the pipe, diameter of the static mixer, etc.) it is possible to realize pore size ranges from 100 µm up to 6 mm. The porosity can be adjusted by the volume flow of slurry and air between 40% and 95%.
Furthermore this study deals with the rheological characterization of unfoamed slurries and wet foams. The Influence of important parameters, such as yield point, viscosity and storage modulus, will be discussed. The measurement of these parameters can be a helpful tool to qualify differences between stable and unstable wet foams.
Both, technological design and a targeted slurry development enable the production of stable foams with a tailored pore structure that can be adjusted to a wide field of applications like heat or sound insulation, lightweight applications, filtration or artificial bone replacement.