Self-healing coatings for multiple action corrosion protection: various approaches and analyses

Transcription

1 Self-healing coatings for multiple action corrosion protection: various approaches and analyses Iris De Graeve Research group of Electrochemical and Surface Engineering SURF Vrije Universiteit Brussel Valorisation scope of Self-Healing materials New constructions s in transport Electronics Heritage projects Offshore Protection of new energy technologies 1

2 Do self-healing coatings already exist and work in real application? YES Early commercial product: >> Worked only on black cars >> Only cosmetic repair... pag. 3 Concept of multiple action self-healing polymer coating 1 2 Self-healing polymer systems Corrosion inhibitors damage 3 Healing of metal through inhibitor release and activity = Autonomous, immediate response 4 Healing of the polymer, autonomous or external trigger Multiple action self-healing corrosion protection coatings pag. 4 2

3 Research consortium VUB: For polymer science: Guy Van Assche, Bruno Van Mele For surface & corrosion science: Iris De Graeve, Herman Terryn Students: Gill Scheltjens, Thibault Muselle, Joost Brancart, Alexander Lutz, Hilke Verbruggen, Mats Meussens, Alexandros Kakaroglou Close collaboration with UGent: - For polymer synthesis: Filip Duprez, Richard Hoogenboom Close collaboration with TU-Delft: - For local electrochemical techniques: Arjan Mol, Yaiza Gonzalez Garcia Close collaboration with University of Aveiro: - Inhibitor encapsulation pag. 5 Evaluation of the performance Methods Local healing in a defect in the coating AFM = Atomic Force Microscopy SVET = Scanning Vibrating Electrode Technique SECM = Scanning Electrochemical Microscopy SIET = Scanning Ion-selective Electrode Technique LEIS = Local Electrochemical Impedance Spectroscopy Surface analysis by SEM, XPS, Raman... Multiple action healing EIS = Electrochemical Impedance Spectroscopy

4 1 Concept of multiple action self-healing polymer coating Self-healing polymer systems Corrosion inhibitors damage Healing of metal through inhibitor release and activity = Autonomous, immediate response Healing of the polymer, autonomous or external trigger Multiple action self-healing corrosion protection coatings pag. 7 First approach to SH: Intrinsic SH by shape memory polymer PCL/PU block copolymer Physical network Soft PCL matrix Hard PU segments 12, 30 & 41 wt% 0, 5, 8, 12 & 16 wt% Soft matrix T m,pcl = 52 C Hard phases < T healing <T m,pu = 173 C Soft PCL segment (8000 g/mol) Hard PU segment (variable length) pag. 8 4

5 Polymer healing action Atomic Force Microscopy Coating thickness 0.5 µm Scratch width 15 µm pag. 9 Polymer healing for corrosion protection Scanning Vibrating Electrode Technique Heating at 40 C 2 days of immersion 1 day of immersion 6 days of immersion Heating at 80 C 5

6 Second approach to SH: Extrinsic SH Autonomous defect repair by encapsulated healing agents Healing agents can be: - Plasticizer in microcapsules - Two components in separate microcapsules e.g. for epoxy healing - Single-reactive healing agent like IPDI in PU-microcapsules: PU microcapsules Second approach to SH: Extrinsic SH Autonomous defect repair by encapsulated single reactive healing agents Corrosion experiment: coating with pin defect after 6 hours in water Proof-of-concept of an autonomous selfhealing coating! Coating without capsules Corrosion at defect site Coating with capsules Limited corrosion Corrosion due to delay between defect event and healing Note: no corrosion inhibitors present yet + slow reacting healing agent - IPDI 6

7 Concept of multiple action self-healing polymer coating 2 Self-healing polymer systems Corrosion inhibitors damage Healing of metal through inhibitor release and activity = Autonomous, immediate response Healing of the polymer, autonomous or external trigger Multiple action self-healing corrosion protection coatings pag. 13 Inhibitor selection and incorporation into coatings Case galvanised steel: inhibitor Mercaptobenzothiazole (MBT) Dissolved in the coating Encapsulated in Porous nanocapsules Layered Double Hydroxides (LDH)

8 Inhibitor incorporation methods Nanocontainers Silica porous nanocontainers nm Layered Double Hydroxides [1] Zheludkevich et al., Nanoscale, 2011 [2] Poznyak et al., Appl. Mat. & Interf., 1, 10, 2353, 2009 Concept of multiple action self-healing polymer coating Self-healing polymer systems Corrosion inhibitors damage 3 Healing of metal through inhibitor release and activity = Autonomous, immediate response Healing of the polymer, autonomous or external trigger Multiple action self-healing corrosion protection coatings pag. 16 8

9 Evaluation of the inhibitor activity in the coating Epoxy-Amine thermoset (non self-healing) Inhibitor (0.4 wt%) added to unreacted components Dissolved In porous silica nanocapsules In LDH Bar coater on HDG 50 µm thick coatings SVET on coating without inhibitors In-situ optical imaging and SVET mapping above two microdrill defects 0 hr of immersion hr of immersion 9

10 SVET on coating with freely dissolved MBT 4 h 4 hr of immersion Lower currents, but coating delamination! SVET on coating with silica NC + MBT For 4 hr of immersion Corrosion inhibition and no coating delamination

11 SVET on coating with LDH + MBT For 4 hr of immersion Corrosion inhibition and no coating delamination Concept of multiple action self-healing polymer coating Self-healing polymer systems Corrosion inhibitors damage Healing of metal through inhibitor release and activity = Autonomous, immediate response 4 Healing of the polymer, autonomous or external trigger Multiple action self-healing corrosion protection coatings pag

12 Multiple action self-healing Electrochemical Impedance Spectroscopy Case aluminium: cerium nitrate inhibitor in intrinsic SH coating Inhibitor mechanism: 23 Multiple action self-healing Electrochemical Impedance Spectroscopy Ce-inhibitor doped SH coating Non-doped SH coating Black: Al substrate Green: Initial coating Red: Scratched coating Blue: Healed coating >> Inhibitor action at low frequencies + polymer healing action at mid-high frequencies 24 12

13 Evaluation of the performance Methods Local healing in a defect in the coating AFM = Atomic Force Microscopy SVET = Scanning Vibrating Electrode Technique SECM = Scanning Electrochemical Microscopy SIET = Scanning Ion-selective Electrode Technique LEIS = Local Electrochemical Impedance Spectroscopy Surface analysis by SEM, XPS, Raman... Multiple action healing EIS = Electrochemical Impedance Spectroscopy Prediction of performance by modelling New project PredictCor Organic Coated s Under Long-term Environmental Corrosion HOW TO BUILD A MECHANISTIC MODEL? AIR δ ELECTROLYTE FILM δ COATING OXIDE METAL 13

14 . BY SUB-SYSTEM APPROACH AIR Sub-system 1 δ ELECTROLYTE FILM Dynamic film model: Evaporation and condensation δ COATING OXIDE METAL Sub-system 2 Model: transport through organic coatings Sub-system 3 Model: delamination of the organic coating Sub-system 4 Model: corrosion of the metal Prediction of durability and lifetime of organic coated metals under long-term environmental corrosion conditions Industrial support committee for PredictCor 14

15 SH research thanks to the support of. Program SHE Self-Healing Engineered materials and all SHE partners! Masterclasses and mini - conference For PhD students and industrial researchers Corrosion: from analysis to modeling 4-8 February, 2019 Vrije Universiteit Brussel Brussels, Belgium Electrochemical Impedance Spectroscopy Surface Analytical Techniques Micro Electrochemical Techniques Numerical Modeling Interested? Ask for a flyer or tom.hauffman@vub.be 15

16 Welcome to EUROCORR 2020 in Brussels!!!! 16