scholarly journals Failure Mechanism of Pure Epoxy Coating in Near-Neutral Solution Focusing on Coating/Metal Interfaces

Author(s):  
Chao Yang ◽  
Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1578 ◽  
Author(s):  
Haijuan Yang ◽  
Qiufeng Mo ◽  
Weizhou Li ◽  
Fengmei Gu

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.


Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1702
Author(s):  
Marjetka Conradi ◽  
Aleksandra Kocijan ◽  
Tadeja Kosec ◽  
Bojan Podgornik

An AISI 316L surface was functionalized by the adsorption of hydrophilic epoxy and epoxy/TiO2/epoxy coatings and hydrophobic epoxy/fluoroalkylsilane-functionalized FAS-TiO2/epoxy coatings. We characterized the coatings’ wettability, morphology and average surface roughness and discussed the influence of surface wettability and morphology on the coefficient of friction and the wear resistance. Experiments were performed in dry, distilled water and in a simulated physiological solution (Hank’s solution). In the case of dry sliding, a lower coefficient of friction is achieved for both TiO2 coatings compared to the pure epoxy coating. In a water environment the same level of friction is shown for all three coatings, whereas in Hank’s solution the friction is reduced for the hydrophilic epoxy/TiO2/epoxy coating, increased for the hydrophobic epoxy/FAS-TiO2/epoxy coating and has no effect on the pure epoxy coating. The results show that the corrosion resistance is significantly improved for the hydrophobic epoxy/FAS-TiO2/epoxy coating compared to the hydrophilic pure epoxy and epoxy/TiO2/epoxy coatings.


2019 ◽  
Vol 795 ◽  
pp. 200-207 ◽  
Author(s):  
Bo Zhao ◽  
Yu Xin Yu ◽  
Tian Yu Zhou ◽  
Shi Wen Zhou ◽  
Jing Guo ◽  
...  

In this article, a set of aging anti-corrosion epoxy coating was prepared in Xenon lamp light chamber of 0h, 72h, 144h, 216h, 288h, 360h and 432h. Meanwhile, the changes of coating thickness, adhesion properties, functional groups, and corrosion resistance properties increasing with aging time were determined. The results showed that the thickness of epoxy coating was increased more than 50% as the aging time increased to 432h, and reached 32μm. The adhesion reduced significantly, which was 0 grade in cross-cut test at 0h, but decreased to 2 grade after been aged for 432h. Meanwhile, the value of adhesive force declined more than 56% in pull-off test. The corrosion resistance properties were investigated by electrochemical impedance spectra (EIS) in both 3.5% NaCl neutral solution (pH=7) and acid solution (pH=2). The Nyquist plots in neutral solution transferred from single time constant to two time constants in neutral solution. The capacitive impedance loop became shorter, while coating resistance Rf declined more rapidly as the aging time increasing. Meanwhile, the Nyquist plots possessed three time constants in acid solutiondue to the dissolution of zinc in the coating. The FT-IR spectrum showed that the peak value of C-O-C and C-H declined with aging time increasing, and the peak of C=O becamemore significantly. The results showed that the protective properties of epoxy coating declined while the aging reaction going on, with chain broken of C-O-C and C-H bond and hydrophilicity enhancing.


AIP Advances ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 035217
Author(s):  
Chao Yang ◽  
Qing Han ◽  
Anquan Wang ◽  
Yong Yang ◽  
Xiyan Li

2013 ◽  
Vol 74 ◽  
pp. 59-70 ◽  
Author(s):  
Ying Liu ◽  
Jiangwei Wang ◽  
Li Liu ◽  
Ying Li ◽  
Fuhui Wang

2015 ◽  
Vol 227 ◽  
pp. 127-130 ◽  
Author(s):  
Linda Diblíková ◽  
Alena Koukalová ◽  
Jan Kudláček ◽  
Michal Zoubek ◽  
František Herrmann

Properties of commercially available epoxy coating were modified using multi-walled carbon nanoparticles (MWCNT) to obtain functional coating with improved abrasion resistance. Simultaneously, corrosion resistance of the epoxy resin could not be negatively affected by the particles addition. Composite coatings with various MWCNT content were prepared and evaluated with regard to their function by abrasion and corrosion tests. We found out that the abrasion resistance of the coatings increased with increasing amount of CNT particles in the matrix. Corrosion protection properties of pure epoxy coating as well as its adhesion were slightly improved by adding 0.5 and 1 wt% MWCNT.


Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.


1978 ◽  
Vol 17 (06) ◽  
pp. 238-248
Author(s):  
H. Beekhuis ◽  
M.A.P.C. van de Poll ◽  
A. Versluis ◽  
H. Jurjens ◽  
M.G. Woldring ◽  
...  

Investigations with bleomycin labelled with radionuclides other than 57Co in patients with cancer and in tumor-bearing animals are described. In patients 57Co-bleo appears to be a better tumor-seeking radiopharmaceutical than 111In-bleo, 99mTc-bleo or 197Hg-bleo. This can be explained by a higher stability in vivo and a better tumor-seeking property of 57Co-bleo and less disturbing activity in the cardiac pool and in bone and other normal tissues when assessing the scintigram.Results with 111In-bleo labelled in acidic solution are not essentially different from those with 111In-bleo labelled in neutral solution.Results of 197Hg-bleo are almost identical with those of 197HgCl2 regarding the tumor-seeking effect as well as the distribution in normal tissues and organs. Probably the complex of 197Hg to bleomycin is not stable in vivo. The superiority of 57Co-bleo over 99mTc-bleo, 197Hg-bleo and also over 67Cu-bleo is confirmed by experiments on tumor bearing animals.We may conclude that the indication for use of bleomycin as a tumor-seeking pharmaceutical labelled with 111In, 99mTc, 197Hg or 67Cu seems to be very limited.


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