Ceramic powders such as alumina can be gelcasted by first electrostatic dispersing the powder in an acid aqueous solution followed by coagulation caused by the addition of alkoxide compounds. A strong, non-complexing acid should be used in order to generate aluminium ions, adsorbed at the surfaces, which enlarge the dispersion degree. The electrically charged groups at the grain surfaces are replaced by non-charged alkoxy compounds which become chemically bonded to the grain surface and lead to coagulation of the ceramic suspension. Various alkoxy compounds can be used leading to different materials, eventuality composites, which are modified at the grain boundaries. Sintering, which is a thermodynamically well-defined process, leads to ceramic materials which can be identical with other ceramics or which can be different, depending on the type of grain boundary modification.
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