Preparation and Characterization of (La_0.9Ca_0.1)(Cr_0.9Mg_0.1)O₃ High Emissivity Coatings Deposited by APS

In this study, (La_0.9Ca_0.1)(Cr_0.9Mg_0.1)O₃ ceramic powders prepared by solid-state synthesis were deposited on nickel-base superalloy substrates by atmospheric plasma spraying. Powder morphology and coating surfaces were examined by SEM, and composition and phase structure were evaluated by EDS and XRD. Coating porosity and bond strength were measured and emissivity and thermal shock tests were carried out. The results show that the powders maintained their perovskite structure during spraying and that no impurities were introduced in flight. The emissivity of the coatings was found to be 0.88 at 600 °C and 0.89 at 800 °C, which is attributed to lattice distortion stemming from differences between doping and original ions and the valence states of Mg²⁺ and Cr³⁺. Coating crystal structure was stable over the thermal shock range from room temperature to 1100 °C and no spalling or fracture occurred after ten shock cycles.