Identification of Inhibitors for Corrosion Protective Compounds

1
Identification of Inhibitors for Corrosion
Protective Compounds

• M. Kendig and M. Hon
• Rockwell Scientific Company LLC
• 1049 Camino dos Rios
• Thousand Oaks, CA 91361
• And
• Joseph Osborne
• Boeing Phantom Works Seattle
• P.O. Box 3999 M/S 73-09
• Seattle, WA 98124-2499

2
Acknowledgement

• W. Abbott (Battelle)
• Joel Johnson (WPAFB/MLBT)
• R. Kinzie (Robins AFB)
• L. Warren (RSC)
• M. Donley

3
Background

• Need Lower cost of ownership
• CPCs and CICs provide easily applied hydrophobic
  barriers for crevices and fay surfaces
• CICs are primarily barriers for corrosives and
  generally do not provide much active inhibition,
  particularly for the ORR.

4
Objective

• Determine whether addition of environmentally
  benign active corrosion inhibitors can improve
  CICs
• Identify the active CICs and methods for
  incorporating in existing CICs

5
Approach

• Choose CICs meeting Boeing BMS 3 - 23
  specification to be modified
• Laboratory screening using EIS and inhibition of
  the oxygen reduction reaction (ORR)
• Accelerated testing
• Salt fog
• Lap joint/filiform
• Outdoor exposure

6
Approach

• Inhibitors
• ORR inhibitors
• Dissolve as complexes with high MW ternary and
  quaternary ammines

7
Baseline Materials
8
Oxygen Reduction at Intermetallics Drives
Corrosion
9
Hydrocarbon-Soluble Ion Complexes Exchange
Release Inhibitor
R are relatively high MW quaterary and ternary
ammines Less mobile Tend to like the oil phase
more than water
10
Inhibitor Release Test
11
Baseline CIC Shows Marginal ORR Inhibition
12
Certain S-Containing Organic Ions Inhibit ORR
13
Modified CICs Inhibit ORR
14
Electrochemical Impedance

• Determine whether addition of inhibitor degrades
  barrier property or enhances the barrier property

15
Accelerated Test
16
Selected Salt Fog Results
17
Selected Lap Shear
Baseline
1 TOA -DMT
5 TOA- PYRR
10 TOA- PYRR
18
Concentration Optimization
A ADDMDTC
19
Outdoor Exposure of Cu Coupons(W. Abbott
Battelle)
Higher sensor output greater corrosion
20
Summary and Conclusion

• Several CICs benefited from the addition of the
  inhibitor TOA-PYRR
• Other ORR inhibitor complexes also demonstrated
  benefit
• Rapid electrochemical tests predict inhibitor
  effectiveness less ability to distinguish
  between different coating systems
• Trade off between ORR inhibition and barrier
  behavior
• Zn stearate generally improved barrier
  properties
• Effectiveness of inhibitors depends on the test
  and the substrate material