Plasma-sprayed aluminum and titanium adherends: 1. Characterization of coatings

The morphological and surface chemical properties of plasma-sprayed coatings on metals have been investigated using surface characterization techniques. Organic polymeric and inorganic powders were plasma-sprayed on aluminum and titanium. Organic-polymeric coatings were prepared using epoxy, polyester, polyimide, and cyanate ester components. Inorganic coatings were obtained by plasma-spraying Al2O3, AlPO4, MgO, and SiO2 on aluminum adherends, and TiO2, TiSi2, MgO, and SiO2 on titanium adherends. The organic-polymeric coatings were prepared at one thickness while the inorganic coatings were sprayed to obtain two different thicknesses. SEM photographs reveal various morphological differences in the sprayed specimens. The surface morphology ranged from smooth to nodular among the plasma-sprayed specimens. Surface chemical analysis of the plasma-sprayed coatings indicated that little or no chemical degradation of the components occurred as a result of plasma-spraying. However, plasma-sprayed TiSi2 appeared to be a mixture of silica and a titanium silicate.