Dispersion of zirconium diboride in an aqueous, high-solids paste

The dispersion of ZrB2 particles was investigated. In aqueous systems, the surface of ZrB2 consists of a thin layer of ZrO2 that controls the surface chemistry and surface charge. Measurements showed that the ZrB2 had an isoelectric point of pH=4.7 and a maximum zeta potential of -50 mV at pH=9. The addition of a dispersant, either an ionic ammonium polyacrylate or a nonionic alkoxylated polyether, increased the zeta potential of ZrB2 by as much as 60 mV to -110 mV. Viscosity measurements were used to optimize dispersant concentrations. High-solids loading (similar to 45 vol.% ZrB2) aqueous pastes were prepared with two different dispersants. The pastes had viscosities of 40-50 Pa.s which was acceptable for extrusion, and were used to fabricate three-dimensional components from ZrB2.