Electrostatic Adsorption of a Colloidal Sintering Agent on Silicon Nitride Particles

Abstract

Pressureless sintering of silicon nitride requires addition of sintering agents. The main part of this study was done in order to homogenize the distribution of sintering agents, in this case Y 2 O 3 , in a silicon nitride matrix. Colloidal 10‐nm Y 2 O 3 Particles were electrostatically adsorbed on Si 3 N 4 particle surfaces. The adsorption was studied by X‐ray fluorescence analysis and electrophoretic measurements. Addition of Y 2 O 3 sol to a Si 3 N 4 suspension decreased the viscosity of the suspension. The slip casting properties of Si 3 N 4 suspensions with added Y 2 O 3 sol were examined, and the homogeneity of Y 2 O 3 in the green compacts was compared with conventionally prepared samples. An improved microstructural homogeneity was obtained when Y 2 O 3 sol particles were adsorbed on the Si 3 N 4 particle surfaces.