An investigation of the dispersion of YSZ, SDC, and mixtures of YSZ/SDC powders in aqueous suspensions for application in suspension plasma spraying

Suspension plasma spraying (SPS) is an emerging technology that can rapidly produce thin, low porosity ceramic layers with no requirement for post deposition heat treatments. However, SPS requires a careful examination of the stability and dispersion of the feedstock suspensions in order to produce high quality coatings. The present study focuses on characterizing the rheology, zeta potential (ZP), particle size, and pH of yttria stabilized zirconia (YSZ), samaria doped ceria (SDC), and mixtures of YSZ and SDC ceramic powders in aqueous suspensions. Three potential dispersant materials were evaluated and optimum suspension formulations with excellent particle dispersion were designed based on rheological and electrostatic stability measurements. These optimized suspensions could be used as feedstock for SPS YSZ or SDC solid oxide fuel cell (SOFC) electrolyte layers or for compositionally graded YSZ/SDC layers.

Research Highlights
► Behavior of YSZ and SDC aqueous suspensions with dispersants was characterized.
► YSZ suspensions – PAA and PBTCA effective at 0.01 wt% and 0.005 wt% respectively.
► YSZ and SDC suspensions – PEI was effective at 0.75 wt% and 2.25 wt% respectively.
► YSZ/SDC mixed suspensions with PEI dispersants showed a great level of stability.