Thermal spray synthesis of functional metal oxides, test methods and applications

Functional metal oxides embody a wide class of materials with multiple applications, such as energy harvesting (thermoelectric), solid oxide fuel cell, energy storage (batteries) and sensor integrated coatings. Their properties are dependent upon the phase composition and its stability. Metal oxide coatings deposited by plasma spray are susceptible to decomposition, formation of intermediate compounds with wide range of nonstoichiometry and metastable phases. By tuning the plasma spray conditions the creation of defects and metastable phases can be controlled. In this work we are going to overview the operational mechanisms of those functional coatings and describe efforts to develop dedicated test methods for functional coatings. In addition, plasma environment-particle interaction is described and correlated to the coating properties, which provides us the opportunity to review in-situ transformations driven by particle morphology, plasma enthalpy and dissimilar vapor pressure material systems.