SiC Products Formed by Slip Casting Method

The paper presents results of research designed to obtain a dense silicon carbide materials shaped by slip casting of aqueous suspensions. Aluminum oxide and yttrium oxide were used as sintering additives in a weight ratio of 3:2 in an amount of 10% by mass relative to the dry weight. The slip was electrostatically stabilized by adjusting pH . Measurement of the zeta potential as a function of pH and viscosity tests as a function of pH and volume fraction of the solid phase allowed for making selection of the suspension parameters, such as the solid volume loading (30%) and pH of ~ 8.5. Results of these investigations confirmed that it is possible to produce pseudoplastic slips suitable for slip casting. The increase in the strength of green bodies, allowing for their green processing, was obtained by addition of a commercial acrylic binder. SiC casts were sintered at 2050°C, which led to materials with high density and fine, homogeneous microstructure. The fracture toughness test revealed a positive effect of the sintering additives on K Ic of the material, increasing its value to approximately 5 MPa·m 1/2 .