Lanthanum Zirconate Thermal Barrier Coating Fabricated by Solution Precursor Plasma Spray Process

An aqueous solution of lanthanum nitrate hexahydrate (La(NO₃)₃×6H₂O) and zirconium acetate (Zr(CH₃CO₂)₄) was plasma sprayed on stainless steel substrates. The shapes of individual particles generated from a single pass of the torch was investigated as a function of plasma enthalpy and spray distance. From the individual particles and splats collected from experiments, the injection history of the solution droplets was studied. The topography and microstructure of the coating cross section produced by multiple passes was examined and correlated with the single pass observations. The thermal conductivity of the as sprayed coated samples and annealed coated samples were measured using the laser flash method.