Effect of surface exposure time on bonds to aluminum

Lap joints with AF‐126 adhesive were prepared from surfaces of 2024‐T3, 2024‐T3 alclad, and 6061‐T4 aluminum alloys treated by either FPL etch, sandblasting, or vapor degreasing. The strength data were described by a two‐parameter Weibull distribution. Allowing between 1 hr and 30 days to elapse between surface preparation and actual bonding had no appreciable effect on bond strength. This was true for all three alloys surface treated in each of the three ways as well as for bonds either tested at ambient conditions or aged for 30 days at 120°F and 95% R.H. 2024‐T3 aluminum, both bare and alclad, formed bonds that showed better strength than 6061‐T4 aluminum.