The effect of corrosion inhibitors on environmental fatigue crack growth in Al–Zn–Mg–Cu

• We are examining the effect of corrosion inhibitors on fatigue damage.
• The amount of inhibitor in each test is related to aircraft relevant geometries to provide useful prediction information.
• A bacterium was noted to provide similar or better corrosion fatigue inhibition than traditional corrosion inhibitors.

Researchers have shown that high levels of chromate added to corrosion fatigue tests on 7xxx series aluminum alloys slows the fatigue crack growth rate (Gasem and Gangloff, 2001; Lui et al., 2003). Corrosion fatigue testing was completed with polymer coating leaching rate relevant inhibitor concentrations to determine the effect on fatigue damage. These results were compared to inhibition by the bacteria Ralstonia pickettii. For the test conditions, the bacteria showed better inhibition than the ionic inhibitors. More research is needed to quantify the mechanical load range and atmospheric corrosion conditions over which ionic inhibition will occur with the low levels of inhibitors available from coatings.