Electrophoretic deposition of zirconia layers for thermal barrier coatings

This paper presents an exploratory investigation of a production route for thermal barrier coatings (TBCs) from a stable zirconia nanopowder suspension by means of electrophoretic deposition (EPD) on a low carbon steel substrate, followed by a consolidation by hybrid microwave sintering. Since the thickness of the green deposit is restricted to a critical thickness, which depends on the curvature of the substrate, a method of repeated deposition and sintering was applied in order to produce thick coatings. The low electric conductivity of the sintered ceramic coating does not inhibit the deposition of additional layers. This method enabled the production of porous coatings with a sintered thickness of 150–300 lm. A finite element model was applied to evaluate the thermal conductivity of the coatings. Values of the order of 0.8 W/mK were obtained which is comparable to that of coatings deposited by other techniques. Hence, the multiple deposited coatings with their thick and porous microstructure have a high potential for thermal barrier coating (TBC) applications.