The nanoscale quantification of the electrochemical behavior in metals is critical to understanding the microstructure-corrosion relationship and subsequently controlling it. In this article, the ...application of advanced surface characterization techniques—atomic force microscopy (AFM), vertical scanning interferometry (VSI), digital holography microscopy (DHM), and other quantitative phase microscopy (QPM) techniques—for surface corrosion monitoring in metals at the micro- and nanoscale are systematically reviewed and discussed in detail. Interestingly in situ, real-time nanoscale topography evolution that enables measurement of time-dependent local dissolution rate as often tracked from numerical construction of QPM is also presented. This study demonstrates the considerable attributes of correlative advanced techniques for identifying nanoscale corrosion mechanisms, enabling the informed development of next-generation inhibition technologies, and improving corrosion predictive models.
Experiments were conducted to investigate the leaching behavior of Zn from end-of-life tire rubber. XRD and XPS analyses showed that the Zn-containing phase in the material was mainly ZnO. SEM-EDS ...analysis confirmed the presence of both exposed and encapsulated ZnO particles. Acid leaching tests indicated that the carbon black comprised in the material can be oxidized and dissolved by HNO3, resulting in the dissolution of completely encapsulated ZnO particles with thinner covering layers. Then, leaching tests using HNO3 as the lixiviant were performed by varying acid concentration and leaching temperature. The results showed over 98% of Zn can be recovered using 2.0 mol/L HNO3 at 90 ℃ after 400 min of reaction. Leaching kinetic results were best fit with the Avrami model, indicating the leaching process was controlled by diffusion. The activation energy determined by Arrhenius formula was 12.92 kJ/mol, which further supports the proposed diffusion controlled leaching process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study combines in situ quantitative phase microscopy - with electrochemical monitoring to evaluate the effect of thermal history on corrosion modes and kinetics of AA6111 alloys. The topography ...map revealed that quenching rates, with or without temper conditions, influenced alloys' corrosion modes despite having similar electrochemical responses and chemical compositions. Primarily, heterogeneous dissolution was observed, with the slow-quenched materials susceptible to intergranular corrosion, while the fast-quenched materials were susceptible to pitting. Quantitative analysis showed the fast-quenched material resisted corrosion initiation for a longer time, with excellent resistance even at higher polarization, compared to slow-quenched material.
•In situ SMI combined with electrochemical monitoring was used to measure the corrosion kinetics of AA6111 alloy.•Alloys quenched at two different rates (i.e., slow-quenched at 131 °C/s and fast-quenched at 506 °C/s) and with different temper modes were tested.•Quantitative corrosion initiation and propagation were assessed.•Heterogeneous dissolution was reported, with the slow-quenched material susceptible to early corrosion than the fast-quenched material.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study applied a novel in situ spectral modulation interferometry (SMI) technique to quantitatively measure the spatiotemporal corrosion kinetics on the surface of low carbon steel. The 3D ...topography map showed an early formation of localised shallow pits on the surface subjected to a chloride-free solution. In contrast, the steel samples in chloride-enriched solution revealed early-age microcracks or intergranular defective sites. The quantitative analysis of the height profile data (acquired from SMI) verified the heterogeneity of the corrosion process of these samples susceptible to pitting corrosion and intergranular corrosion behaviour. The estimated volume loss followed a similar trend to the 3D surface topography data. Still, a distinct behaviour in the volume loss was observed when compared to the void volume obtained from the electrochemical data.
End-of-life tire (ELT) rubber has been widely researched to replace fine or coarse aggregates in cementitious composites. While most studies paid attention to its effect on the engineering ...properties, very few considered chemical reactions with pore solution and the potential for environmental leachate. Recently the authors developed a methodology to remove zinc from the ELT rubber, since zinc can be toxic if it is leached into the environment. In this study, the authors utilized ELT rubber before and after the zinc extraction process to partially replace fine aggregate in a mortar. Flowability, compressive strength, flexural strength, and ultrasonic pulse velocity were measured for the engineering properties of rubberized mortars. Simultaneously, isothermal calorimetry was also employed to investigate the effects of ELT rubber on the hydration process of the rubberized mortars. In addition, the pore solution and leaching solutions were taken at different curing ages and then analyzed for elemental and total organic carbon (TOC) contents. The results showed a remarkable loss in engineering properties of rubberized mortar when ELT rubber was utilized, and the decrease in performance was more pronounced in the samples with zinc-extracted ELT rubber. The pore solution was found to contain significant quantities of zinc and TOC. However, the authors also found that using silica fume to partially replace cement could effectively recover the loss in strength and could reduce the leachability of zinc and TOC.
•A metallurgical processing technique is implemented to leach zinc from end-of-life tire rubber.•The fate of zinc and organic carbon leached from end-of-life tire rubber is studied.•Cement-based materials are proven effective to immobilize zinc and organic carbon leached from tire rubber.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This research study presents a novel application of a quantitative phase microscopy technique, spectral modulation interferometry (SMI), for in situ nanoscale characterization of corrosion of an ...aluminum alloy in real time. SMI offers high sensitivity, rapid image acquisition, and speckle-free images; thus, real-time quantification of surface topography evolution during corrosion can be obtained accurately to evaluate the temporally- and spatially-dependent corrosion rates. With an innovative additive-manufactured fluid cell, experiments were performed in situ under flowing solution conditions. Electrochemical tests via stepwise polarization and solution chemistry through collected aliquots of outflow solution were also performed alongside the nanoscale SMI experiment to simultaneously provide a corroborating corrosion rate measurement. Based on the quantitative 3D height profiles across the corroded surface, pit formation resulting from rapid local corrosion was predominant, appearing at different times and are heterogeneously distributed across the surface. The computed time-dependent dissolution rates of aluminum also varied as the experiment proceeded, with the combination of linear and nonlinear surface normal distributions. An initial mean linear dissolution rate of 0.40 ± 0.007 μmol m−2 s−1 transitioned to a more rapid mean rate of 1.95 ± 0.035 μmol m−2 s−1, driven by the anodic polarization. Dissolution rates from the three performed methods follow similar trends and there is the visibility of linking the nanoscale in situ SMI data to the electrochemical corrosion measurements and ex situ chemical solution analysis. At the end of the corrosion period, rates of 118 μmol m−2 s−1, 71 μmol m−2 s−1, and 2.45 μmol m−2 s−1 were obtained from electrochemical measurements, ex situ solution analyses, and in situ SMI corrosion measurement, respectively. Finally, these experimental results validate the applicability of SMI for in situ nanoscale characterization of a corroding alloy surface.
•This research study presents a novel application of a quantitative phase microscopy technique, spectral modulation interferometry (SMI).•The SMI data offer real time surface topography measurements, enabling evaluation of time-dependent surface normal dissolution rates.•The combination of SMI with the E–i response is valuable in providing additional data for both electrochemical and topographical changes.•Pitting corrosion was predominant, appearing at different times, and are heterogeneously distributed across the surface.•The study provides a better construction of corrosion models for practical implications and applications in corrosion engineering.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, SBCE, UL, UM, UPCLJ, UPUK, ZAGLJ
Abstract
This work studies the mechanical and chemical effects of utilizing baghouse dust (BHD) from secondary aluminum processing waste as a cement additive for potential use in concrete materials. ...The baghouse dust was added to cement pastes at replacements of 4 % and 8 % by cement mass. In addition, a combination of BHD and silica fume at different blended ratios were added to the cement mixture as a combined additive. Some reference proportions were also prepared for a comprehensive comparison. Unconfined compressive strength and the chemical composition of the extracted pore solution of the abovementioned hardened cement pastes were investigated. In addition, the effect of BHD on the hydration characteristics of the cement paste was also observed through isothermal calorimetry. It was found that an 8 % substitution of cement by BHD resulted in increased compressive strength after 1 day and 3 days of curing and a reduction of less than 2 % at 7 days of curing. Comparatively, samples with 8 % silica fume resulted in a strength increase of 17 %. As such, it was concluded that BHD addition of up to 8 % was not detrimental to concrete strength but did not improve performance either. This finding was supported by isothermal calorimetry data, which showed that the addition of BHD and the addition of silica fume both increased the initial peak of hydration and accelerated the hydration process but did not significantly impact the total energy of hydration over a period of 7 days. Finally, the high chloride content in BHD may promote corrosion in steel bars and increase concrete scaling potential.
Cementitious binders have become increasingly complex in their variety, mineralogical and chemical compositions, and structure over the past several decades, and there is no sign that the trend will ...stop or reverse in the future. Strategies for handling the complexity fall into one of two categories: (1) increasingly laborious trial-and-error exploration of the design space and mixture qualification process, or (2) systematic development of structure-property relationships, through curation of fundamental material component data and validated modeling based on fundamental scientific principles. The latter approach requires a sustained research investment and has received comparatively little attention in the concrete materials community. Nevertheless, the long-term benefits of determining structure-property relationships arguably far outweigh the costs. This paper describes general measurement and modeling strategies for developing structure-property relationships and suggests how the existence of comprehensive materials data repositories and scientific modeling tools could revolutionize concrete materials design, including design for service life.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
Abstract
Curing temperature is widely known for its effects on the strength of various cementitious-based civil engineering materials, including in stabilized soils. Curing materials at different ...temperatures can cause negative or positive impacts on the mechanical properties of these materials due to the effect of temperature on hydration behavior, hydration rate, and ion exchange. This paper aims to better understand these factors in geoengineering applications. In particular, the discussion focuses on the effects of curing temperatures ranging from below freezing to 50 °C on the hydration process of cement paste (
i.e.
, hydration rate, mineral dissolution, compressive strength) and the hydration process and strengthening mechanism of cement-stabilized soils. Finally, an informative table listing the advantages and disadvantages of the influences of each temperature level on these materials is provided as a summary of the findings from the literature.
