1. -Phosphate post-treatment of spontaneous spray deposited cerium-based conversion coatings (CeCCs) on Al 2024-T3 increases their corrosion performance -The effect of phosphate source on the surface morphology, electrochemical response, and corrosion performance of CeCCs was characterized -Multifunctional UV coatings were spray deposited onto CeCCs on Al 2024-T3 -The performance of MUV coatings were evaluated for salt spray corrosion testing, wet tape adhesion, and filiform corrosion Evaluation of Multifunctional UV (MUV) Curable Corrosion Coatings on High Strength Aluminum Alloy Substrates M. O’Keefe (PI), W. Fahrenholtz, D. Heller, W. Gammil, A. Thomas Develop a Two Layer, Chromate-Free, Zero TRI/VOC/HAPs Corrosion Coating System for DoD Metallic Substrates Objective Metallic Substrate Chromate Conversion Coating Strontium Chromate Primer Organic Top Coat Metallic Substrate Non-Chromate Conversion Coating UV-Curable Coating Current 3 Layer SystemProposed 2 Layer System J. DeAntoniB. Curatolo SERDP Project WP-1519 The guidance and support of Bruce Sartwell of SERDP and Donna Ballard of AFRL/ML are gratefully acknowledged Overview CeCC Surface Morphology CeCC Potentiodynamic Scans NH 4 H 2 PO 4 K4P2O7K4P2O7 Na 2 H 2 P 2 O 7 Na 5 P 3 O 10 As Deposited NH 4 H 2 PO 4 K4P2O7K4P2O7 Na 5 P 3 O 10 Na 2 H 2 P 2 O 7 Na 3 PO 4 -Post-treatment reduces cracking of the CeCC compared to as-deposited films CeCC XRD Analysis Corrosion Performance As Deposited Na 3 PO 4 CeCC EIS Spectra CrCC w/ MUV CeCC w/ MUV Spray MUV Evaluation Cr (VI) Control -Orthophosphate post-treatments showed the fewest pits and least salting after 14 days of salt spray exposure 3000 hr Salt Spray 3000 hr Stripped Wet Tape Adhesion Filiform Corrosion -Post-treatment solutions affect pitting potential (E pit ) and corrosion current (i corr ). Conclusions -Electrochemical data correlate to results from salt spray corrosion testing and can be used to predict performance -The spray MUV coatings used with CrCCs offers comparable, or better, corrosion protection to the Cr (VI) Control without VOCs, HAPS or TRI chemicals in the coating. -Adhesion/blistering exhibited by the MUV coatings on CeCCs is related to the thickness; thinner CeCCs perform better -Orthophosphates charge transfer resistance >2X higher than pyrophosphates and >10X higher than polyphosphate or unsealed CeCCs -The formation of CePO 4 H 2 O is believed to improve corrosion resistance -The MUV coating on a chromate-based conversion coating (CrCC) performs as well as the Cr (VI) Control in salt spray and adhesion tests -MUV coatings on CeCCs performed worse than the Cr (VI) Control and CrCC w/ MUV for each of the tests (CeCC too thick). -MUV coatings on thinner CeCCs (fewer spray cycles) have higher adhesion and do not blister after curing. E pit = -343 mV I corr = 2.14 µA/cm 2 E pit = -420 mV I corr = 1.36 µA/cm 2 E pit = -322 mV I corr = 1.17 µA/cm 2 E pit ≈ -280 mV I corr ≈ 0.45 µA/cm 2 E pit = -261 mV I corr = 0.60 µA/cm 2 E pit = -275 mV I corr = 0.74 µA/cm 2 E pit i corr