Influence of ammonium salt of poly-methacrylic acid and butylamine addition on the viscosity and electrophoretic deposition behavior of ethanol-based powder suspensions

Ethanol-based Al2O3 and Ce-ZrO2 suspensions are stabilized with ammonium poly-methacrylate (Darvan-C) and n-butylamine. The effect of the additives on the suspension stability is studied by zeta potential and viscosity measurements. When n-butylamine is added to the particles dispersed in ethanol, the suspension is electrostatically stabilized, the viscosity decreases and a shear-thinning behavior is observed. The suspensions stabilized with Darvan-C have a low Newtonian viscosity at concentrations above 140 μl/g. The polyelectrolyte is a more efficient dispersant than the organic base due to electrosteric stabilization. When the suspension is stabilized with n-butylamine prior to Darvan-C addition, stable suspensions are obtained when the n-butylamine or Darvan-C concentration is kept low. The wet deposit obtained from the suspensions stabilized with different BA concentrations and more than 100 μl/g of Darvan-C deforms under its own weight. When Darvan-C is adsorbed on the particles prior to n-butylamine addition, the suspensions have a low viscosity and a Newtonian behavior and the wet EPD deposit is smooth and rigid.