Modeling of MRP Protection Considering Chemical Inhibition, Electrochemistry, and Mass Transport
Abstract
Aluminum alloy AA2024-T3 is widely used in aerospace applications due to its high strength-to-weight ratio. However, because of its heterogeneous microstructure, it is susceptible to microgalvanic corrosion and pitting in chloride containing environments, requiring additional corrosion protection methods. Organic coatings are the primary corrosion protection method used in aluminum alloys and they are usually composed of pigments embedded in a polymeric matrix. The polymeric matrix promotes a high resistance to ionic movement and it provides barrier against the ingress of aggressive species onto the substrate. The pigments can provide corrosion protection by inhibiting corrosion reactions, providing cathodic protection to the substrate, and/or depositing a protective layer on the surface of the substrate. Recently, a coating system containing a Mg-rich primer (MgRP) has emerged as an effective alternative to the chromate-based coatings commonly used for this purpose. Due to the lower potential of Mg, MgRP can protect aluminum alloys via galvanic coupling, serving as a sacrificial anode and preventing the corrosion of the Al substrate. Additionally, recent studies showed that the electrolyte chemistry resulting from Mg dissolution is beneficial to localized corrosion inhibition of AA2024, providing corrosion protection even after pigment depletion.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 23, 2020
- Source ID
- 10.1149/ma2020-02131345mtgabs
Entities
People
- Carolina Vicente Moraes
- John R. Scully
- Raymond Santucci
- Robert Kelly