Influence of the different organic chelating agents on the topography, physical properties and phase of SPPS-deposited spinel ferrite splats

Different types of organic chelating agents (polyvinyl alcohol, citric acid, and oxalic acid) were added during the preparation of cobalt ferrite precursor. The resulting cobalt ferrite solutions were then used in the solution precursor plasma spray (SPPS) process to deposit single splats onto mild steel substrates. It was revealed that the thermal oxidation of cobalt and iron salts into cobalt monoxide (CoO), maghemite (γ-Fe2O3), cobalt oxide (Co3O4), cobalt oxyhydroxide (CoOOH), goethite (α-FeOOH), hematite (α-Fe2O3), magnetite (Fe3O4), and cobalt ferrite (CoFe2O4) occurred largely within the deposited splats. The surface topographies of the splats exhibited unmolten, partially molten, and completely molten splats. The type of organic chelating agents affected significantly the splat thickness, percentage of cobalt ferrite phase, degree of splashing and equivalent diameter of the splats.