Materials Engineering Department
BS in Materials Engineering
Katherine C. Chen
P2 etchant is an environmentally-friendly aluminum etchant which has the potential to replace the Forest Products Laboratory (FPL) etchant as the industry standard. Environmental durability of adhesively-bonded aluminum surfaces etched using a paste version of the P2 etchant were tested using the Boeing-developed wedge test (ASTM D3762 - 03(2010)). This project specifically aimed to examine the relationship between outlife time (the time between etching and adhering) and the ability of bonded aluminum samples to pass the wedge test. Two aluminum alloys, 2024-T3 and 7075-T6, were wedge tested and the etched surfaces examined with an atomic force microscope (AFM) and a scanning electron microscope (SEM). The etchant improved durability of the bonded specimens and helped produce passing 2024 specimens for times ranging up to one week. Results of the 2024 testing demonstrated slightly decreased bond durability on average with increased outlife times, while the results of the 7075 testing were less conclusive and require more investigation to make meaningful conclusions. With more 2024 testing, the data could ideally be used to find a consistent critical outlife time near where bond durability decreases below the minimally-acceptable value. The results of this study may help Raytheon Company to improve their manufacturing procedures by defining a broader range of acceptable outlife times.