The Durability of Adhesively-Bonded Titanium: Performance of Plasma-Sprayed Polymeric Coating Pretreatments

Non-solution and electrochemical treatments in preparation for adhesive 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 surfaces were characterized using infrared, solid state NMR, and surface-sensitive analytical methods. The chemical nature of plasma-sprayed polymers is equivalent to that for powdered materials. The durability of titanium, adhesively bonded with a polyimide adhesive, was investigated 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 analytical methods. Surface treatments using plasma-sprayed LaRC-type polyimides result in good durability as evidenced by minimal crack growth for wedge specimens and by failure in the adhesive (cohesive failure).