In this study, different sets of plasma-sprayed YSZ thermal barrier coatings were deposited via Ar/H 2 and N 2 /H 2 plasmas and compared based on deposition efficiency (DE), thermal conductivity (TC), and furnace cycle testing (FCT). The top-performing coatings exhibited equivalent FCT lifetimes with TC values in the range of 1.15-1.25 W/mK at 1200 °C, but the deposition efficiency of those produced with N 2 /H 2 plasma was twice as high, resulting in a 55% reduction in production costs.

Molten calcium-magnesium-aluminum-silicate (CMAS) particles cause significant degradation of thermal barrier coatings (TBCs) in aero-engines. One way to protect TBCs against CMAS attack is through the application of a sacrificial topcoat. In this work, Al 2 O 3 coatings were deposited on top of EB-PVD 7wt% YSZ layers via suspension thermal spraying using an aqueous Al 2 O 3 suspension. Spray parameters were varied in order to obtain Al 2 O 3 layers with two different microstructures and porosity levels. The coating systems were evaluated by means of CMAS infiltration testing at 1250 °C. It was found that the porosity and morphology of Al 2 O 3 strongly influence CMAS infiltration and the formation of reaction products and that CMAS mitigation is a function of coating morphology and the speed at which Al 2 O 3 reacts with CMAS deposits.

In this study, NbC coatings, 250 µm thick, were deposited by low-velocity flame spraying on stainless steel substrates and were laser remelted in a controlled argon atmosphere. Isolated passes transverse of the coatings were performed at different focal lengths at speeds of 10, 15, and 20 mm/min. Using the selected laser parameters, layers were recast with eight passes at 10% superposition. Erosion-corrosion tests were performed and coating surfaces and cross-sections were characterized via SEM, EDS, and XRD analysis. Modified surfaces of dense, 800-µm thick coatings with no defects and excellent metallurgical bonding with the substrate were obtained. It was found that dilution of the coating with the substrate formed a gradient of chemical composition and mechanical properties and that erosive-corrosive wear resistance was highest for an erodent impact angle of 90°.