Pasa-Jell-107 method

T. J. St. Clair (MASA Langley Re6eaAch CentoX) The PASA-JELL 107 method was used for cleaning all of adherends used in the presented work. The phosphate-fluoride treatment was studied in our lab and was found to give the same lap shear results at room temperature on the systems that were tested. 

Panels of Ti-6-4 alloy adherend were obtained from the NASA-Langley Research Center. The panels were either used in the as-received condition or cleaned by the Pasa-Jell 107 method, a commercial process (American Cyanamid ) for cleaning titanium alloy surfaces. The primary steps in this cleaning process are, briefly sample immersion in degreasing 1,2-Tdichloroethane immersion in an alkaline cleaner, SPREX AN 9 solution pickling in an HNO3/HF solution and treatment with Pasa-Jell 107 (a chromate based acid paste). 

The cut samples were secured to the ESCA probe with double-sided tape. ESCA spectra also were obtained for Ti-6-4 samples in the as-received condition and cleaned by the Pasa-Jell method, and coated with the polymer resin. Two polymer coated samples were prepared by placing a 0.01 ml of 14% and 25% dilutions in diglyme of the stock resin solution of BTDA and m,m DABP on cleaned Ti-6-4 panels. Each drop spread spontaneously over the entire sample surface. The samples were dried at room temperature for at least 24 hours prior to the ESCA and contact angle runs. 

IR reflectance spectra were obtained for the fractured samples of Set II. The samples were placed in the reflectance attachment so that the lapped portion of the panels covered the entire sample window. This method allowed spectra of the samples to be obtained in situ. Comparisons of intensities of individual peaks in the different sample spectra proved to be unsatisfactory in evaluating the amount of adhesive present on a panel. For this reason, reflectivity as measured by percent transmission in a non-absorbing region (2600 cm ) was considered as a possible characterization of the fracture surface. The percent transmission in this region was measured for each sample and also for a polished Ti-6-4 surface and a Pasa-Jell cleaned Ti-6-4 surface. 

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