Showing papers on "Corrosion published in 2021"

Horizontally Arranged Zinc Platelet Electrodeposits Modulated by Fluorinated Covalent Organic Framework Film for High-Rate and Durable Aqueous Zinc Ion Batteries

Abstract: Rechargeable aqueous zinc-ion batteries (RZIBs) provide a promising complementarity to the existing lithium-ion batteries due to their low cost, non-toxicity and intrinsic safety. However, Zn anodes suffer from zinc dendrite growth and electrolyte corrosion, resulting in poor reversibility. Here, we develop an ultrathin, fluorinated two-dimensional porous covalent organic framework (FCOF) film as a protective layer on the Zn surface. The strong interaction between fluorine (F) in FCOF and Zn reduces the surface energy of the Zn (002) crystal plane, enabling the preferred growth of (002) planes during the electrodeposition process. As a result, Zn deposits show horizontally arranged platelet morphology with (002) orientations preferred. Furthermore, F-containing nanochannels facilitate ion transport and prevent electrolyte penetration for improving corrosion resistance. The FCOF@Zn symmetric cells achieve stability for over 750 h at an ultrahigh current density of 40 mA cm−2. The high-areal-capacity full cells demonstrate hundreds of cycles under high Zn utilization conditions. Rechargeable aqueous zinc-ion batteries are promising but the zinc anode suffers from dendrite growth and electrolyte corrosion. Here, the authors develop a fluorinated covalent organic framework film as a protective layer for aqueous zinc anode battery.

Growth of NiAl‐Layered Double Hydroxide on Graphene toward Excellent Anticorrosive Microwave Absorption Application

Abstract: High-performance microwave absorbers with special features are desired to meet the requirements of more complex modern service environments, especially corrosive environments. Therefore, high-efficiency microwave absorbers with corrosion resistance should be developed urgently. Herein, a 3D NiAl-layered double hydroxide/graphene (NiAl-LDH/G) composite synthesized by atomic-layer-deposition-assisted in situ growth is presented as an anticorrosive microwave absorber. The content of NiAl-LDH in the composite is optimized to achieve impedance matching. Furthermore, under the cooperative effects of the interface polarization loss, conduction loss, and 3D porous sandwich-like structure, the optimal NiAl-LDH/G shows excellent microwave absorption performance with a minimum reflection loss of -41.5 dB and a maximum effective absorption bandwidth of 4.4 GHz at a loading of only 7 wt% in epoxy. Remarkably, the encapsulation effect of NiAl-LDH can restrain the galvanic corrosion owing to graphene. The epoxy coating with the NiAl-LDH/G microwave absorber on carbon steel exhibits long-term corrosion resistance, owing to the synergetic effect of the superior impermeability of graphene and the chloridion-capture capacity of the NiAl-LDH. The NiAl-LDH/G composite is a promising anticorrosive microwave absorber, and the findings of this study may motivate the development of functional microwave absorbers that meet the demands of anticorrosive performance of coatings.

A comparative study on microstructure and properties of traditional laser cladding and high-speed laser cladding of Ni45 alloy coatings

Abstract: High-speed laser cladding technology can significantly improve the efficiency of coating preparation and effectively widen the application range of laser cladding. In this study, the Ni45 powders were deposited on steel substrate by traditional low speed laser cladding and high-speed laser cladding process, respectively. The cladding efficiency, surface forming, cross-sectional microstructure, microhardness, wear and corrosion resistance properties of the traditional and high-speed laser cladded Ni45 alloy coatings were compared. It can be seen that the thickness of the high-speed laser cladding coating was much thinner than that of the traditional laser cladding coating. Compared with traditional laser cladding, high-speed laser cladding could achieve a cladding speed of 76.86 m/min and a cladding efficiency of 156.79 cm2/min. The microstructure of the two kinds of coatings shows the same growth law, but the microstructure in high-speed laser cladding was smaller and denser, and the columnar crystal interval was narrower, only about 6 μm. It is found that the cooling rate of the traditional laser cladding coating was smaller than that of the high-speed laser cladding, and as the cladding speed increased, the cooling rate became higher and higher. The cross-section microhardness of the traditional laser cladding coating was relatively uniform of 337 HV0.2, while the microhardness of high-speed laser cladding surface increased to about 543 HV0.2. In addition, the wear and corrosion resistance of high-speed laser cladded coatings were better than that of traditional laser cladded coatings. As the cladding speed increased, the wear and corrosion resistance of the cladded coatings became better.

Fundamental understanding of carbonation curing and durability of carbonation-cured cement-based composites: A review

Abstract: To tackle the rising CO2 concentration in atmosphere, technologies of carbon sequestration are emerging. As one of these technologies, carbonation curing of cement-based composite at early age shows a great potential because its wide application and benefits to provide cement-based composite with enhanced mechanical properties and durability. However, carbonation curing is mostly investigated on lab-scale, due to two main challenges that should be addressed before it can be widely applied for industrial-scale production: (1) CO2 sequestration rate is still low, which is around 20 %–50 % of the theoretical potential because of the limitation of CO2 diffusion into matrix during the carbonation curing; and (2) the effect carbonation curing on the durability of cement-based composites and the underlying mechanisms remains unclear, especially for some critical aspects such as alkali-silica reaction, corrosion, and sulfate attack. Therefore, this paper focuses on discussing: (1) factors affecting CO2 sequestration in cement-based composite during each stage of carbonation curing and the optimization methods of carbonation curing for high CO2 sequestration rate without mitigating mechanical properties and durability, and (2) effects of carbonation curing on different aspects of durability and the corresponding mechanisms. Based on the review, future studies on addressing current challenges are inspired to comprehend and promote the carbon sequestration by carbonation curing of cement-based composites.

Recent developments in sustainable corrosion inhibitors: design, performance and industrial scale applications

Abstract: Recently, research studies in the fields of science and engineering are directed towards the synthesis, design, development, and consumption of environment-friendly chemical species to replace traditional toxic chemicals. This is because of the escalating demands of conservation understanding and stringent ecological rules. Currently, various environment-friendly alternatives derived from natural resources such as biopolymers, plant extracts, chemical medicines (drugs), etc. are widely used to replace toxic corrosion inhibitors. Moreover, various biopolymers in their pure and modified forms are extensively employed as environment-friendly corrosion inhibitors. Compounds derived through multicomponent reactions (MCRs), and microwave (MW) and ultrasound (US) irradiations are also considered as environment-friendly alternatives. Polyethylene glycol (PEG) and ionic liquids (ILs) possess low vapor pressure and are regarded as designer environment-friendly alternatives. The chemicals synthesized using green solvents such as water, ILs and supercritical CO2 can also be regarded as environment-friendly chemical species. A comprehensive literature survey reveals that these compounds are extensively utilized as metallic corrosion inhibitors in various corrosive electrolytes. Overall, this review provides a summary of several major reports on environment-friendly corrosion inhibitors.

Stainless steel corrosion via direct iron-to-microbe electron transfer by Geobacter species.

Abstract: Microbial corrosion of iron-based materials is a substantial economic problem. A mechanistic understanding is required to develop mitigation strategies, but previous mechanistic studies have been limited to investigations with relatively pure Fe(0), which is not a common structural material. We report here that the mechanism for microbial corrosion of stainless steel, the metal of choice for many actual applications, can be significantly different from that for Fe(0). Although H2 is often an intermediary electron carrier between the metal and microbes during Fe(0) corrosion, we found that H2 is not abiotically produced from stainless steel, making this corrosion mechanism unlikely. Geobacter sulfurreducens and Geobacter metallireducens, electrotrophs that are known to directly accept electrons from other microbes or electrodes, extracted electrons from stainless steel via direct iron-to-microbe electron transfer. Genetic modification to prevent H2 consumption did not negatively impact on stainless steel corrosion. Corrosion was inhibited when genes for outer-surface cytochromes that are key electrical contacts were deleted. These results indicate that a common model of microbial Fe(0) corrosion by hydrogenase-positive microbes, in which H2 serves as an intermediary electron carrier between the metal surface and the microbe, may not apply to the microbial corrosion of stainless steel. However, direct iron-to-microbe electron transfer is a feasible route for stainless steel corrosion.