Corrosion and Materials Degradation

14 pages, 7398 KiB

Open AccessArticle

Corrosion Inhibitory Effects of Mullite in Concrete Exposed to Sulfuric Acid Attack

by Shima Taheri, Gerardo Pareja Delgado, Oluwatoosin B. A. Agbaje, Paritosh Giri and Simon Martin Clark

Corros. Mater. Degrad. 2020, 1(2), 282-295; https://doi.org/10.3390/cmd1020014 - 1 Sep 2020

Cited by 11 | Viewed by 4050

Abstract

Prolonged exposure to low pH conditions affects the durability of concrete. In this work, the effect of mullite, aluminum silicate, on the strength and the acid corrosion of mortar and concrete under induced accelerated conditions in sulfuric acid solutions at pH of 0.25 and 1 was studied. The characterization of physicochemical changes was performed using techniques including compressive strength, scanning electron microscopy, micro-X-ray fluorescence spectrometry, and the Vickers hardness test. The results indicate that the addition of mullite does not have any significant effect on the overall strength of mortar and concrete samples, while it significantly increases their resistance to corrosion caused by sulfate attack by 90%, therefore, it is expected to increase the life span and decrease the maintenance costs of concrete pipes subjected to acid corrosion in sewer environments. The inhibition efficiency is observed to be sensitive to acid concentration and was improved with increase in the amount of mullite in samples. Full article

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9 pages, 1545 KiB

Open AccessPerspective

Finite Element Method for Thin Film Corrosion Modelling: Where We Advanced and Where We would like to Advance?

by Mohsen Saeedikhani and Daniel John Blackwood

Corros. Mater. Degrad. 2020, 1(2), 273-281; https://doi.org/10.3390/cmd1020013 - 19 Aug 2020

Cited by 14 | Viewed by 3449

Abstract

Thin film corrosion is a serious issue in almost every sector. Thus, simulation of corrosion under thin electrolyte films has always been of high interest as experimental studies are often challenging. Thus far, progress has been made to model the effect of several important factors on thin film corrosion rates. Some of these parameters are electrolyte thickness, electrolyte composition, chemical reactions in the electrolyte, electrode size and change in electrode size, environmental parameters, and corrosion products deposition. However, these parameters are mainly drawn from different studies and have not been modelled concurrently in a single simulation study, making the thin film corrosion model far from being complete yet. Therefore, despite the many efforts so far, thin film corrosion modelers still strive to push the modelling edges further. This paper takes into account some of the highlighted recent advances in thin film corrosion modelling based on the mentioned parameters to provide a perspective on not only how far the field has come, but also how far it still is from a complete thin film corrosion model. Discussions have also been made on future needs and prospects to advance the thin film corrosion models further. Full article

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24 pages, 8212 KiB

Open AccessFeature PaperArticle

Electrochemical Behavior of Al–Al₉Co₂ Alloys in Sulfuric Acid

by Athanasios K. Sfikas and Angeliki G. Lekatou

Corros. Mater. Degrad. 2020, 1(2), 249-272; https://doi.org/10.3390/cmd1020012 - 5 Aug 2020

Cited by 15 | Viewed by 4713

Abstract

Al–Co alloys of various Co contents (2–20 wt.% Co) were fabricated by vacuum arc melting (VAM) with the scope to investigate the influence of cobalt on the microstructure and corrosion resistance of Al in 1 M H₂SO₄. The obtained microstructures were directional, consisting of Al₉Co₂ platelets (grown to coarse acicular plates as the Co content increased) uniformly dispersed in an Al-matrix. Alloying Al with Co did not decrease the rate of uniform corrosion of Al but it considerably increased its passivation ability. Moreover, all Al–Co alloys displayed lower uniform corrosion rate and notably higher passivation ability than market leading Al-alloys. The underlying mechanisms during anodic polarization in 1 M H₂SO₄ were identified and correlated with the microstructure. High Co content alloys (7–20 wt.% Co) presented superior passivation ability in 1 M H₂SO₄ as compared to the low Co content alloys. Full article

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30 pages, 7551 KiB

Open AccessReview

Corrosion Modeling of Magnesium and Its Alloys for Biomedical Applications: Review

by Moataz Abdalla, Alexander Joplin, Mohammad Elahinia and Hamdy Ibrahim

Corros. Mater. Degrad. 2020, 1(2), 219-248; https://doi.org/10.3390/cmd1020011 - 31 Jul 2020

Cited by 36 | Viewed by 7386

Abstract

Biodegradable metals have been under significant research as promising alternatives to the currently in-use nonbiodegradable materials in the field of supportive medical implants. In this scope, magnesium and its alloys were widely investigated due to their superior biocompatibility over other metals. Most of the research effort in the literature has been focused on assuring the biocompatibility, improving mechanical properties, and tailoring the corrosion rate of magnesium-based implants. Furthermore, considerable research was done to develop numerical models towards an inexpensive and fast designing tools capable of simulating the degradation/corrosion behavior of magnesium-based implants. Due to the complexity of the degradation process and the various factors that can be involved, several hypotheses were introduced to provide a realistic simulation of the corrosion behavior in vitro and in vivo. A review of the current literature hypothesis and different modeling constitutive equations for modeling the corrosion of magnesium alloys along with a summary of the supplementary experimental methods is provided in this paper. Full article

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Corros. Mater. Degrad., Volume 1, Issue 2 (September 2020) – 4 articles

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