A single splat is the building block of a thermal spray coating; thus, investigating single splats is essential to understanding thermal spray coatings and their properties. In this study, the morphology of flame sprayed ethylene methacrylic acid (EMAA) splats, deposited at various stand-off distances (SODs) onto glass and mild steel substrates were investigated using a scanning electron microscope, Leica M Stereo-microscope, the WYKO surface profiler and the ContourGT surface profiler. This work analyzed the effect of the process variables on EMAA splat morphology. The modeling of the temperature versus velocity (TV) map, the temperature versus stand-off distance (TS) map and the velocity versus stand-off distance (VS) map of EMAA single splat were presented.

In this study, the microstructure and electrochemical and passive characteristics of NiCr_25.2−xMoAl_x (x = 0, 1.25, 2.5, and 5 mol.%) alloys were investigated. The results show that Ni-Cr-Mo-Al alloys with varying Cr:Al ratios both had a single FCC structure without any second structure precipitates, and decreases in dislocation density and grain size were observed as the Al content in NiCrMoAl alloys increased. It was found from the electrochemical results that the NiCr_23.95MoAl_1.25 alloys had the maximum radius for a semicircle and the lowest I_corr, indicating an enhanced anti-corrosion performance (R_ct: 8.08 ± 0.368 × 10⁵ Ω cm², I_corr: 1.05 ± 0.003 × 10⁻⁷ A/cm²). In this study, it was found that the anti-corrosion performance of the alloys had an approximate connection to the composition and density of passive films. Denser and more stable microstructures in NiCr_23.95MoAl_1.25 alloys were further proven by potentiostatic polarization tests and Mott–Schottky experiments, showing a lower stable current density and acceptor density (N_A: 9.79 ± 0.4 × 10⁻²⁰ cm⁻³). In addition, the results of XPS show that the Al_1.25 specimen had the highest Cr₂O₃ in the passive film’s content among the NiCrMoAl alloys. Cr₂O₃ was the main component, suggesting an enhanced protective influence of passive film. The present study can offer guidance for the application of nickel-based alloys with high anti-corrosion resistance in marine environments.