Modeling of Inhibitor Release from Organic Coating Using Finite Element
Method in Assisting in the Multifunctional Organic Coating Design
Hongwei Wang ([email protected]) and Robert Kelly ([email protected])
Summary: Several strategies for the control of solubility and delivery of inhibitors in
organic coatings are being explored in a DoD MURI. One method uses anion-exchanging
hydrotalcites (HTs). Buchheit et al. have demonstrated the inhibition of AA2024-T3
corrosion by the migration of VO3- released from a HT.
(mol/m3)
Inhibitor Concentration
The mode of corrosion protection envisioned is for HTs to reside at a metal surface as a
conversion coating or as a pigment in the primer coating. In the presence of an attacking
solution, HT anion exchange will
2500 µm scratch
release of an inhibiting anion into the
solution and absorb and immobilize
2
the attacking ion or ions. This study
0.1 s
1.6
extends the early crevice corrosion
100 s
300 s
modeling
work
to
inhibitor
500 s
1.2
release/aggressive
anion
capture
Scratch
0.8
from/to HT in epoxy coatings. The
inhibition
(48%)
kinetics of the bare Al alloy were
0.4
determined
from
separate
0
electrochemical
measurements.
0
0.002
0.004
0.006
0.008
0.01
Similarly inhibitor release kinetics and
Distance (m )
diffusion parameters were assumed
based on measurements on virgin
epoxy films.
Water layer
(500 µm)
The objectives of this study are:
HT inhibitor particles
1) Develop a computational model for Primer coating
(15-20 µm)
the inhibitor release and transport
within and from the hydrotalcite Substrate
AA2024
High aluminum dissolution
coating system to assist in the design
rate in scratch
of the multifunctional coating system
with the encapsulated inhibitors. The
model and source code will be also released via http://www.virginia.edu/cese/research/
crevicer/.
2) Study the influence to the corrosion inhibition of: inhibitor release rate, inhibitor
loading, polymer resins, chloride gettering rate, scratch size, water layer thickness, NaCl
concentration.
This modeling study is associated with another experimental study of release and
transport of chemical species within and from functional coatings.
Current sponsors: Air Force Scientific Research Officer (AFOSR)