A systematic study on Si3N4 slip processing is presented. Stable well dispersed aqueous suspensions with high solid contents can be prepared with an adequate control of the electrophoretic and rheological properties. The influence of these parameters on the kinetics of slip casting and pressure slip casting processes is studied. X-ray photoelectron spectroscopy (XPS) analysis has shown that the optimisation of processing conditions as for example liquid vehicle, pH and the characteristics of the deflocculant, allows the control of the oxidation level at the particle surface. After sintering, dense Si3N4 compacts (> 96% TD) are obtained with good mechanical properties ( E = 312 GPa, K IC = 6.6 MPa.m1/2) at room temperature as well as at high temperature (1200-1300°C), in the same range of values reported in the literature.
silicon nitride; slip casting; surface chemistry; rheology
