Korrelationen in der Kette Pulvereigenschaften - Processing - Werkstoff- und Bauteileigenschaften

The influence of the powder properties and the processing conditions on the ceramic material properties are discussed with respect to silicon nitride ceramics. The surface of several Si3N4-powders can be modified by treatment with fluoric acid. The isoelectric point shifts from a pH range between 5,0 and 6,3 for the starting powders to a pH range between 8,2 and 8,7 for the acid treated powders. The changed surface chemical properties of the powders influence the adsorption of the deflocculant and thus the viscosity of aqueous slips. A comparison of several processing routes shows that the mechanical strength of the sintered material can by increased by optimum use of the electrokinetic principles for the stabilization of the suspension (pH, deflocculant).