Failure Surface Analysis of Polyimide/Titanium Notched Coating Adhesion Specimens

Adhesively-bonded joints of LaRC^TM PETI-5, a phenylethynyl-terminated polyimide, with chromic acid anodized titanium were fabricated and debonded interfacially. The adhesive-substrate failure surfaces were investigated using several surface analysis techniques. From Auger spectroscopy, field emission scanning electron microscopy, and atomic force microscopy studies, polymer appears to be penetrating the pores of the anodized substrate to a depth of approximately 100 nm. From X-ray photoelectron spectroscopy data, the polymer penetrating the pores appears to be in electrical contact with the titanium oxide, leading to differential charging. These analyses confirm that the polymer is becoming mechanically interlocked within the substrate surface.