High Velocity Suspension Flame Spraying and Suspension Plasma Spraying of Oxide Ceramics

Thermal spraying of oxide ceramic suspensions containing fine and ultra fine powder particles is a new approach for manufacturing ceramic coatings exhibiting a refined microstructure. Suspension sprayed coatings clearly differ from conventionally sprayed coatings regarding microstructure phase composition and resulting mechanical properties.

Several industrial applications may take advantage in future, among these are thermal barrier structures, thermal shock protection, solid electrolytes, catalytically active surfaces and wear resistant coatings.

Two methods, namely suspension plasma spraying (SPS) and high velocity suspension flame spraying (HVSFS) are suitable to process suspensions but lead to rather different coating structures due to differences in the achievable particle velocities and temperature. Generally, HVSFS can lead to more dense coatings with low porosity values. With SPS on the other hand, coatings with a high volume fraction of porosity featuring a homogeneous pore structure is achievable. The presentation will compare SPS and HVSFS regarding the spray process, achieved properties of the oxide coatings and potential applications.