Metal‐organic Surfactants as Sintering Aids for Silicon Nitride in an Aqueous Medium

Abstract

Interaction between two commercial silicon nitride powders and various metal‐organic surfactants was investigated in an aqueous medium to obtain a homogeneous distribution of sintering aid. Conditions under which the silicon nitride particles could be coated with metal oxide sintering aids were identified. Acoustophoresis, XPS, TEM, and FTIR were used to characterize the interaction between the metalorganic and the silicon nitride powder. From these data, the mechanism of attachment of the coatings was proposed. The surface area and surface chemistry of the powder, the pH of the solution, the structure of the surfactant, and the surface charge behavior of the powder and the coating were found to be the crucial parameters. The control of these parameters offered a simple and reproducible method to homogeneously distribute various metal oxides. Multicomponent coatings were also possible. The coated powders containing 0.5–4 wt% sintering aid could be compacted to 72% green density.