Showing papers on "Corrosion published in 2017"

Corrosion-Resistant High-Entropy Alloys: A Review

Abstract: Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs) possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods on the corrosion resistance are analyzed in detail. Furthermore, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.

Suppression of Dendrite Formation and Corrosion on Zinc Anode of Secondary Aqueous Batteries

Abstract: Novel zinc anodes are synthesized via electroplating with organic additives in the plating solution. The selected organic additives are cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), polyethylene-glycol (PEG-8000), and thiourea (TU). The synthesized zinc anode materials, namely, Zn-CTAB, Zn-SDS, Zn-PEG, and Zn-TU, are characterized by powder X-ray diffraction and scanning electron microscopy. The results show that each additive produces distinctively different crystallographic orientation and surface texture. The surface electrochemical activity is characterized by linear polarization when the zinc is in contact with the battery’s electrolyte. Tafel fitting on the linear polarization data reveals that the synthetic zinc materials using organic additives all exhibit 6–30 times lower corrosion currents. When using Zn-SDS as the anode in the rechargeable hybrid aqueous battery, the float current decreases as much as 2.5 times. The batteries with Zn-SDS, Zn-PEG, and Zn-TU anodes display ...

Application of superhydrophobic coatings as a corrosion barrier : a review

Abstract: This review provides an overview of recent advances in the application of superhydrophobic surfaces to act as corrosion barriers. The adverse consequences of corrosion are a serious and widespread problem resulting in industrial plant shutdowns, waste of valuable resources, reduction in efficiency, loss or contamination of products, and damage to the environment. Superhydrophobic surfaces, inspired by nature, can be considered as an alternative means for improving the protection of metals against corrosion. Due to the possibility of minimizing the contact area between liquids and a surface, superhydrophobic surfaces can offer great resistance to corrosion. Artificial superhydrophobic surfaces have been developed with the potential of being applied in numerous settings including self-cleaning, anti-icing, oil-water separation, and especially anti-corrosion applications. In this paper, we review the concept of superhydrophobicity through presentation of different theoretical models. The fabrication and application of superhydrophobic surfaces are presented, and we then discuss the use of superhydrophobic coatings as barriers against the corrosion of metals.

Surface Fluorination of Reactive Battery Anode Materials for Enhanced Stability.

Abstract: Significant increases in the energy density of batteries must be achieved by exploring new materials and cell configurations. Lithium metal and lithiated silicon are two promising high-capacity anode materials. Unfortunately, both of these anodes require a reliable passivating layer to survive the serious environmental corrosion during handling and cycling. Here we developed a surface fluorination process to form a homogeneous and dense LiF coating on reactive anode materials, with in situ generated fluorine gas, by using a fluoropolymer, CYTOP, as the precursor. The process is effectively a “reaction in the beaker”, avoiding direct handling of highly toxic fluorine gas. For lithium metal, this LiF coating serves as a chemically stable and mechanically strong interphase, which minimizes the corrosion reaction with carbonate electrolytes and suppresses dendrite formation, enabling dendrite-free and stable cycling over 300 cycles with current densities up to 5 mA/cm2. Lithiated silicon can serve as either a...

Carbon steel corrosion: a review of key surface properties and characterization methods

Abstract: Corrosion is a subject of interest to interdisciplinary research communities, combining fields of materials science, chemistry, physics, metallurgy and chemical engineering. In order to understand mechanisms of corrosion and the function of corrosion inhibitors, the reactions at the interfaces between the corrosive electrolyte and a steel surface, particularly at the initial stages of the corrosion process, need to be described. Naturally, these reactions are strongly affected by the nature and properties of the steel surfaces. It is however seen that the majority of recent corrosion and corrosion-inhibition investigations are limited to electrochemical testing, with ex situ analysis of the treated steels (post-exposure analysis). The characterization of materials and their surface properties, such as texture and morphology, are not being considered in most studies. Similarly, in situ investigations of the initial stages of the corrosion reactions using advanced surface characterization techniques are scarce. In this review, attention is brought to the importance of surface features of carbon steels, such as texture and surface energy, along with defects dislocation related to mechanical processing of carbon steels. This work is extended to a critical review of surface analytical techniques used for characterization of carbon steels in corrosive media with particular focus on examining steel surfaces treated with corrosion inhibitors. Further, emerging surface analysis techniques and their applicability to analyse carbon steels in corrosive media are discussed. The importance of surface properties is commonly addressed by surface scientists as well as researchers in other chemistry fields such as nanotechnology, fuel cells, and catalysis. This article is expected to appeal to a broad scientific community, including but not limited to corrosion scientists, material chemists, analytical chemists, metal physicists, corrosion and materials engineers.

Numerical Modelling of Effects of Biphasic Layers of Corrosion Products to the Degradation of Magnesium Metal In Vitro.

Abstract: Magnesium (Mg) is becoming increasingly popular for orthopaedic implant materials. Its mechanical properties are closer to bone than other implant materials, allowing for more natural healing under stresses experienced during recovery. Being biodegradable, it also eliminates the requirement of further surgery to remove the hardware. However, Mg rapidly corrodes in clinically relevant aqueous environments, compromising its use. This problem can be addressed by alloying the Mg, but challenges remain at optimising the properties of the material for clinical use. In this paper, we present a mathematical model to provide a systematic means of quantitatively predicting Mg corrosion in aqueous environments, providing a means of informing standardisation of in vitro investigation of Mg alloy corrosion to determine implant design parameters. The model describes corrosion through reactions with water, to produce magnesium hydroxide Mg(OH) 2 , and subsequently with carbon dioxide to form magnesium carbonate MgCO 3 . The corrosion products produce distinct protective layers around the magnesium block that are modelled as porous media. The resulting model of advection-diffusion equations with multiple moving boundaries was solved numerically using asymptotic expansions to deal with singular cases. The model has few free parameters, and it is shown that these can be tuned to predict a full range of corrosion rates, reflecting differences between pure magnesium or magnesium alloys. Data from practicable in vitro experiments can be used to calibrate the model's free parameters, from which model simulations using in vivo relevant geometries provide a cheap first step in optimising Mg-based implant materials.

Biodegradable Materials and Metallic Implants-A Review.

Abstract: Recent progress made in biomaterials and their clinical applications is well known. In the last five decades, great advances have been made in the field of biomaterials, including ceramics, glasses, polymers, composites, glass-ceramics and metal alloys. A variety of bioimplants are currently used in either one of the aforesaid forms. Some of these materials are designed to degrade or to be resorbed inside the body rather than removing the implant after its function is served. Many properties such as mechanical properties, non-toxicity, surface modification, degradation rate, biocompatibility, and corrosion rate and scaffold design are taken into consideration. The current review focuses on state-of-the-art biodegradable bioceramics, polymers, metal alloys and a few implants that employ bioresorbable/biodegradable materials. The essential functions, properties and their critical factors are discussed in detail, in addition to their challenges to be overcome.

Corrosion of high entropy alloys

Abstract: High entropy alloys represent a unique class of metal alloys, comprising nominally five or more elements in near equiatomic proportions. High entropy alloys have gained significant interest on the basis that the high configurational entropy of such alloy systems is purported to result in a single-phase solid solution structure. While such a single-phase structure can occur in unique systems, it is now appreciated that the definition of high entropy alloys can be broader, with systems comprising only four elements possible of forming single phases, and most five (or more) element systems actually being multi (>2) phases. To this end, the notion of compositionally complex alloys is a more general description, with the concise review herein focusing on the corrosion of compositionally complex alloys (inclusive of high entropy alloys). It is noted that generally, in spite of complex compositions and in many cases complicated microstructural heterogeneity, compositionally complex alloys are nominally corrosion-resistant. This is discussed and aspects of the status and needs are presented.

Protective coatings on zirconium-based alloys as accident-tolerant fuel (ATF) claddings

Abstract: Abstract Surface-modified zirconium (Zr)-based alloys, mainly by fabricating protective coatings, are being developed and evaluated as accident-tolerant fuel (ATF) claddings, aiming to improve fuel reliability and safety during normal operations, anticipated operational occurrences, and accident scenarios in water-cooled reactors. In this overview, the performance of Zr alloy claddings under normal and accident conditions is first briefly summarized. In evaluating previous studies, various coating concepts are highlighted based on coating materials, focusing on their performance in autoclave hydrothermal corrosion tests and high-temperature steam oxidation tests. The challenges for the utilization of coatings, including materials selection, deposition technology, and stability under various situations, are discussed to provide some valuable guidance to future research activities.

Corrosion‐Resistant Superhydrophobic Coatings on Mg Alloy Surfaces Inspired by Lotus Seedpod

Abstract: Superhydrophobic surfaces are widely found in nature, inspiring the development of excellent antiwater surfaces with barrier coatings isolating the underlying materials from the external environment. Here, the naturally occurring superhydrophobicity of lotus seedpod surfaces is reported. Protective coatings that mimic the lotus seedpod are fabricated on AZ91D Mg alloy surfaces with the synergistic effect of robust superhydrophobicity and durable corrosion resistance. The predesigned titanium dioxide films are coated on AZ91D by an in situ hydrothermal synthesis technique. Through sonication assisted electroless plating combined with a self-assembling method, the densely packed Cu-thiolate layers are uniformly plated with robust adhesion on the Mg alloy substrate, which function as a superhydrophobic barrier that can hold back the transport of water and corrosive ions contained such as Cl−. Notably, the two extreme wetting behaviors (superhydrophilicity and superhydrophobicity) as well as corrosion resistance and improved corrosion resistance can be easily controlled by removal of the hydrophobic materials (n-dodecanethiol) at elevated temperature (350 °C) and modifying them at room temperature for 18 cycles, indicative of exceptional adhesion between the superhydrophobic coating and the underlying AZ91D Mg alloy.

Robust Slippery Coating with Superior Corrosion Resistance and Anti-Icing Performance for AZ31B Mg Alloy Protection.

Abstract: Biomimetic slippery liquid-infused porous surfaces (SLIPSs) are developed as a potential alternative to superhydrophobic surfaces (SHSs) to resolve the issues of poor durability in corrosion protection and susceptibility to frosting. Herein, we fabricated a double-layered SLIPS coating on the AZ31 Mg alloy for corrosion protection and anti-icing application. The porous top layer was infused by lubricant, and the compact underlayer was utilized as a corrosion barrier. The water-repellent SLIPS coating exhibits a small sliding angle and durable corrosion resistance compared with the SHS coating. Moreover, the SLIPS coating delivers durable anti-icing performance for the Mg alloy substrate, which is obviously superior to the SHS coating. Multiple barriers in the SLIPS coating, including the infused water-repellent lubricant, the self-assembled monolayers coated porous top layer, and the compact layered double hydroxide–carbonate composite underlayer, are suggested as being responsible for the enhanced corros...

On the corrosion and metastable pitting characteristics of 316L stainless steel produced by selective laser melting

Abstract: The austenitic stainless steel 316L was additively manufactured using Selective Laser Melting (SLM). The corrosion characteristics of the additively manufactured (3D printed) specimens were investigated by both potentiodynamic and potentiostatic techniques. The production parameters were deliberately varied during SLM, to produce 316L specimens fabricated by different laser scan speed (in the range of 860–1160 mm/s) and laser power (in the range of 165–285 W). The fabrication parameters were found to influence the porosity of the resulting specimens. The pitting potentials, metastable pitting rates and repassivation potentials of the 3D printed specimens are presented herein as a function of the laser scan speed and laser power, and also discussed in the context of specimen porosity. The corrosion characteristics of the 3D printed 316L were also compared with wrought 316L, revealing higher pitting potentials and lower rates of metastable pitting for most SLM 316L specimens, the related concepts of which are discussed herein. © The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. [DOI: 10.1149/2.0551706jes] All rights reserved.

Inorganic–Organic Coating via Molecular Layer Deposition Enables Long Life Sodium Metal Anode

Abstract: Metallic Na anode is considered as a promising alternative candidate for Na ion batteries (NIBs) and Na metal batteries (NMBs) due to its high specific capacity, and low potential. However, the unstable solid electrolyte interphase layer caused by serious corrosion and reaction in electrolyte will lead to big challenges, including dendrite growth, low Coulombic efficiency and even safety issues. In this paper, we first demonstrate the inorganic–organic coating via advanced molecular layer deposition (alucone) as a protective layer for metallic Na anode. By protecting Na anode with controllable alucone layer, the dendrites and mossy Na formation have been effectively suppressed and the lifetime has been significantly improved. Moreover, the molecular layer deposition alucone coating shows better performances than the atomic layer deposition Al2O3 coating. The novel design of molecular layer deposition protected Na metal anode may bring in new opportunities to the realization of the next-generation high ene...