The self-healing evaluation of microcapsule-based epoxy coatings applied on AA6061 Al alloy in 3.5% NaCl solution

2017 ◽  
Vol 64 (2) ◽  
pp. 225-232 ◽  
Author(s):  
Mehdi Shahidi Zandi ◽  
Majdeh Hasanzadeh
Keyword(s):  
Electrochemical Impedance ◽  
Linseed Oil ◽  
Theoretical Estimate ◽  
The Self ◽  
Al Alloy ◽  
Self Healing ◽  
Nacl Solution ◽  
Epoxy Coatings ◽  
Water Emulsion ◽  
Content Type

Purpose The aim of this work is to investigate the self-healing performance of epoxy coatings containing microcapsules. The microcapsule-based coatings were applied on AA6061 Al alloy and immersed in 3.5 per cent NaCl solution. Design/methodology/approach Microcapsules with urea–formaldehyde as the shell and linseed oil as the healing agent were prepared by in situ polymerization in an oil-in-water emulsion. For the sake of an optimum self-healing system, some coating samples were prepared by using different microcapsule concentrations: 0, 5, 10 and 20 Wt.%. The scratch-filling efficiency as the theoretical estimate of the self-healing performance was calculated for the coating samples with different microcapsule concentrations. The scratch-sealing efficiency (SSE) as a particularly crucial parameter in the self-healing evaluation of coatings was measured by both electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) techniques. Findings According to EIS and EN results, the coating samples containing 5 and 10 per cent microcapsules provided the insignificant self-healing performance, while the coating sample containing 20 per cent microcapsules exhibited the acceptable self-healing performance to AA6061 alloy in the NaCl solution. The measured SSE values confirmed the good agreement of EN data with electrochemical parameters obtained from the EIS technique. Originality/value This work is an attempt to evaluate the self-healing performance of microcapsule-based epoxy coatings applied on AA6061 Al alloy in sea water.

scholarly journals Preparation and Properties of Self-Healing and Self-Lubricating Epoxy Coatings with Polyurethane Microcapsules Containing Bifunctional Linseed Oil

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1578 ◽  
Author(s):  
Haijuan Yang ◽  
Qiufeng Mo ◽  
Weizhou Li ◽  
Fengmei Gu
Keyword(s):  
Interfacial Polymerization ◽  
Electrochemical Impedance ◽  
Linseed Oil ◽  
Salt Spray ◽  
Average Diameter ◽  
Organic Coating ◽  
Epoxy Coating ◽  
The Self ◽  
Self Healing ◽  
Pure Epoxy

An organic coating is commonly used to protect metal from corrosion, but it is prone to failure due to microcracks generated by internal stress and external mechanical action. The self-healing and self-lubricating achieved in the coating is novel, which allows an extension of life by providing resistance to damage and repair after damage. In this study, a new approach to microencapsulating bifunctional linseed oil with polyurethane shell by interfacial polymerization. Moreover, the self-healing and self-lubricating coatings with different concentrations of microcapsules were developed. The well-dispersed microcapsules showed a regular spherical morphology with an average diameter of ~64.9 μm and a core content of 74.0 wt.%. The results of the salt spray test demonstrated that coatings containing microcapsules still possess anticorrosion, which is improved with the increase of microcapsules content, after being scratched. The results of electrochemical impedance spectroscopy showed a |Z|f=0.01Hz value of 104 Ω·cm2 for pure epoxy coating after being immersed for 3 days, whereas the coating with 20 wt.% microcapsules was the highest, 1010 Ω·cm2. The results of friction wear showed that the tribological performance of the coating was enhanced greatly as microcapsule concentration reached 10 wt.% or more, which showed a 86.8% or more reduction in the friction coefficient compared to the pure epoxy coating. These results indicated that the coatings containing microcapsules exhibited excellent self-healing and self-lubricating properties, which are positively correlated with microcapsules content.

scholarly journals Design of self-healing catalysts for aircraft application

2018 ◽  
Vol 9 (6) ◽  
pp. 723-736 ◽  
Author(s):  
Elisa Calabrese ◽  
Pasquale Longo ◽  
Carlo Naddeo ◽  
Annaluisa Mariconda ◽  
Luigi Vertuccio ◽  
...  
Keyword(s):  
Ruthenium Catalysts ◽  
The Self ◽  
Self Healing ◽  
Catalytic Systems ◽  
Content Type ◽  
Aerospace Applications ◽  
Healing Efficiency ◽  
Relevant Role ◽  
Aircraft Application

PurposeThe purpose of this paper is to highlight the relevant role of the stereochemistry of two Ruthenium catalysts on the self-healing efficiency of aeronautical resins.Design/methodology/approachHere, a very detailed evaluation on the stereochemistry of two new ruthenium catalysts evidences the crucial role of the spatial orientation of phenyl groups in the N-heterocyclic carbene ligands in determining the temperature range within the curing cycles is feasible without deactivating the self-healing mechanisms (ring-opening metathesis polymerization reactions) inside the thermosetting resin. The exceptional activity and thermal stability of the HG2MesPhSyncatalyst, with the syn orientation of phenyl groups, highlight the relevant potentiality and the future perspectives of this complex for the activation of the self-healing function in aeronautical resins.FindingsThe HG2MesPhSyncomplex, with the syn orientation of the phenyl groups, is able to activate metathesis reactions within the highly reactive environment of the epoxy thermosetting resins, cured up to 180°C, while the other stereoisomer, with the anti-orientation of the phenyl groups, does not preserve its catalytic activity in these conditions.Originality/valueIn this paper, a comparison between the self-healing functionality of two catalytic systems has been performed, using metathesis tests and FTIR spectroscopy. In the field of the design of catalytic systems for self-healing structural materials, a very relevant result has been found: a slight difference in the molecular stereochemistry plays a key role in the development of self-healing materials for aeronautical and aerospace applications.

Cellulose microfibers (CMFs) as a smart carrier for autonomous self-healing in epoxy coatings

2020 ◽  
Vol 44 (15) ◽  
pp. 5702-5710 ◽  
Author(s):  
Muddasir Nawaz ◽  
Sehrish Habib ◽  
Adnan Khan ◽  
R. A. Shakoor ◽  
Ramazan Kahraman
Keyword(s):  
Corrosion Inhibition ◽  
The Self ◽  
Self Healing ◽  
Epoxy Coatings ◽  
Cellulose Microfibers

.The cellulose microfibers (CMFs) were synthesized to assist the self-release of loaded product, that provides better corrosion inhibition and self-healing of epoxy coatings.

Research on the Repair Performance of Self-Healing Aluminum Material Based on the Low Melting Point Slicker Solder Alloy

2018 ◽  
Vol 932 ◽  
pp. 57-61
Author(s):  
Wei Sun ◽  
Rong Xin Yan ◽  
Li Chen Sun ◽  
Zheng Li ◽  
Guan Qing Lang ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Melting Point ◽  
Matrix Material ◽  
High Energy ◽  
The Self ◽  
Al Alloy ◽  
Self Healing ◽  
Material Technology ◽  
Damage Repair ◽  
Aluminum Alloy 6063

It is great significance to study self-healing aluminum alloy materials for spacecraft the structure protection from high energy space weapon attack and debris impact in future. In this paper, Using aluminum alloy (6063) as matrix material with low melting point alloy (Sn60Pb40, the melting point of 183°C) as repairing materials, the self-healing Aluminum Alloy material was designed and manufactured by the smelting and casting method. The crack damage repair performance of the self-healing Al alloy was researched through the experiment. The results show that the self-healing aluminum alloy has certain self-healing ability without help, when the temperature reaches the melting point temperature of Sn60Pb40. The repair time is about 20min, the crack filling rate can reach 84%. The research conclusion can provide a reference for the development of metal self-healing material technology.

Applicability of EIS for evaluation of corrosion resistance of aluminum flakes

2016 ◽  
Vol 63 (5) ◽  
pp. 355-359
Author(s):  
Naghmeh Amirshaqaqi ◽  
Mehdi Salami-Kalajahi ◽  
Mohammad Mahdavian
Keyword(s):  
Corrosion Resistance ◽  
Conventional Method ◽  
Design Methodology ◽  
Electrochemical Impedance ◽  
Quantitative Estimation ◽  
Surface Modifications ◽  
Organic Coatings ◽  
Nacl Solution ◽  
Content Type ◽  
Alkaline Conditions

Purpose The conventional method for evaluation of corrosion resistance of aluminum flakes is based on the volume of evolved hydrogen in acidic and basic environments. This study aims to introduce electrochemical impedance spectroscopy (EIS) as a method to evaluate corrosion resistance of aluminum flakes. Design/methodology/approach Aluminum flakes with different surface modifications were compressed to build a disk. Then, the disks were examined by EIS in NaCl solution. Also, the corrosion resistance of the flakes was evaluated by the conventional method. Findings The results revealed applicability of EIS for evaluation of corrosion resistance of aluminum flakes. Originality/value Application of EIS to evaluate corrosion resistance of aluminum flakes is novel. As it can provide fast, reliable and quantitative estimation of the corrosion resistance of the aluminum flakes in the 3.5 per cent NaCl solution. This medium is highly encountered for the aluminum flakes used in organic coatings, that is why test in NaCl solution is more convenient compared to the conventional methods using acid and alkaline conditions.

Corrosion protective properties of coatings doped with inhibitors

2014 ◽  
Vol 61 (6) ◽  
pp. 416-422 ◽  
Author(s):  
Mansoureh Parsa ◽  
Seyed Mohammad Ali Hosseini ◽  
Zahra Hassani ◽  
Effat Jamalizadeh
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Titania Nanoparticles ◽  
Self Healing ◽  
Properties Of Coatings ◽  
Ethylene Imine ◽  
Protective Properties ◽  
Content Type

Purpose – The purpose of this paper was to study the corrosion resistance of water-based sol-gel coatings containing titania nanoparticles doped with organic inhibitors for corrosion protection of AA2024 alloy. Design/methodology/approach – The coatings were obtained using tetraethylorthosilicate, 3-glycidoxypropyltrimethoxysilane, titanium (IV) tetrapropoxide and poly(ethylene imine) polymer as cross-linking agents. As corrosions inhibitors, 2-mercaptobenzoxazole and salicylaldoxime were incorporated into the sol-gel for the improvement of the corrosion resistance. The corrosion protection performance of coatings was studied using the potentiodynamic scan and the electrochemical impedance spectroscopy (EIS) methods. Atomic force microscopy was used to investigate surface morphology of the coatings. Findings – The results indicated that doping the sol-gel coatings with inhibitors leads to improvement of the corrosion protection. The comparison of doped coatings confirmed that corrosion protection performance of the sol-gel coatings doped with 2-mercaptobenzoxazole was better than for the sol-gel coatings doped with salicylaldoxime. Also the EIS results verified self-healing effects for the sol-gel coatings doped with 2-mercaptobenzoxazole. Originality/value – This paper indicates 2-mercaptobenzoxazole and salicylaldoxime can be added as corrosion inhibitors to sol-gel coatings to improve their corrosion protective properties for AA2024 alloy.

The effect of polyurethane-isophorone microcapsules on self-healing properties of an automotive clearcoat

2016 ◽  
Vol 45 (2) ◽  
pp. 73-78 ◽  
Author(s):  
Pooneh Kardar
Keyword(s):  
Infrared Spectra ◽  
Scratch Resistance ◽  
The Self ◽  
Spherical Particles ◽  
Self Healing ◽  
Content Type ◽  
Smart Coatings ◽  
Healing Agent ◽  
Reported Data ◽  
Practical Implications

Purpose – The purpose of this work was to prepare a catalyst-free microcapsules as self-healing agent in an automotive clearcoat to improve the scratch resistance of coatings. Design/methodology/approach – In this research, microcapsule with isophorone diisocyanate (IDPI) core and polyurethane shell were prepared and used in self-healing coatings. Microcapsules synthesised were characterised by thermal gravimeter and infrared spectra. The microcapsules were dispersed in an acrylic-melamine clearcoat, and the scratch resistance was evaluated. Findings – The triplex product and the formed polyurethane bonds were confirmed by thermal gravimeter and infrared spectra. In addition, smooth spherical particles with a diameter of 1.5 to 1.7 micronmeters were observed by a scanning electron microscope. The microcapsules dispersed in an acrylic-melamine clearcoat increased the scratch resistance of coatings. Also, the self-healing feature of those coatings was proved. Research limitations/implications – The size of microcapsules can affect its dispersion in the clearcoat and consequently affect the properties of the cured films. Practical implications – The self-healing coatings are interested for many industries such as building and automotive industries. The reported data can be used by the formulators working in the R & D departments. Social implications – Self-healing systems are considered as one of the smart coatings. Therefore, the developing of its knowledge can help to extend its usage to different applications. Originality/value – The application of microcapsules in the coating as healing agents is a great challenge, which has been hardly investigated so far. In the current research, the effect of polyurethane-IDPI microcapsules in an automotive clearcoat as a self-healing coating was investigated.

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