Chemical modification of LDH conversion coating with diethyldithiocarbamate as a novel anti-corrosive film for AA2024-T3

Abstract

Nowadays, layered double hydroxide conversion coatings are a potential eco-friendly alternative for hazardous and carcinogenic chromate conversion coatings. In this work, Zn-Al LDH conversion coating (LDH−CC) modified with diethyldithiocarbamate (DEDTC) molecules, as a smart inhibitive film, was synthesized on AA2024-T3. For this purpose, the LDH−CC was prepared on the AA2024-T3 by an in-situ hydrothermal route, and then intercalated with DEDTC molecules through an anion-exchange procedure. The intercalation of the DEDTC into the structure of the LDH−CC was studied using XPS, XRD, ATR-FTIR, SEM-EDS, and TGA techniques. All of the characterization techniques proved the successful intercalation of the DEDTC molecules in the structure of the LDH−CC. Results indicated that the chemical modification treatment increases in the gallery space of LDH−CC by the intercalation of DEDEC molecules in the coating structure. Also, electrochemical tests were implemented in 3.5 wt. % NaCl media to study the anti-corrosion performance of the coatings. The electrochemical test results showed that the presence of the DEDTC molecules dramatically enhanced the anti-corrosion behavior of the LDH−CC due to the induction of the active inhibition mechanism.