THE DURABILITY OF ADHESIVELY-BONDED TITANIUM - PERFORMANCE OF PLASMA-SPRAYED POLYMERIC COATING PRETREATMENTS

Non-solution and electrochemical treatments in preparation for adhesiv e bonding of titanium have been studied. Polymeric materials, LaRC TPI -2000(TM) LaRC PETI-5(TM) and Aurum(TM) polyimides were deposited onto titanium-6Al-4V surfaces via plasma spraying. The plasma-sprayed surf aces were characterized using infrared, solid state NMR, and surface-s ensitive analytical methods. The chemical nature of plasma-sprayed pol ymers is equivalent to that for powdered materials. The durability of titanium, adhesively bonded with a polyimide adhesive, was investigate d by immersing wedge-type specimens in boiling water. Crack length and the mode of failure were used to assess durability. The determination of the failure mode was accomplished using surface-sensitive analytic al methods. Surface treatments using plasma-sprayed LaRC-type polyimid es result in good durability as evidenced by minimal crack growth for wedge specimens and by failure in the adhesive (cohesive failure).