SURFACE CHARACTERIZATION AND ADHESION OF PLASMA-SPRAYED ADHERENDS

The physical and chemical properties of plasma-sprayed coatings on met als have been investigated through surface characterization techniques . The durability of plasma-sprayed metals bonded with epoxy and polyim ide adhesives was studied. Polymer and inorganic powders were plasma-s prayed on aluminum and titanium. Polymer powders included an epoxy, an d a polyester. and a bismaleimide/cyanate ester mixture. Inorganic coa tings included Al2O3, AlPO4, MgO, and SiO2 on aluminum adherends, and TiO2, TiSi2, MgO, and SiO2 on titanium adherends. Inorganic coatings w ere sprayed at two different coating thicknesses. All plasma-sprayed p olymer coatings had a Smooth appearance. The inorganic specimens exhib ited differences in the coating uniformity aid the particle surface mo rphology. Durability studies using samples prepared in wedge and butt- torsion geometries were carried out. Bonded specimens were exposed to an environmental cycle that included vacuum at high temperature, cold temperature, and high relative humidity. Time to failure and mode of f ailure for the samples were measured.