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This study provides new insights into the development of high-performance MXene-reinforced coatings to strengthen polymeric nanocomposites by enhancing microstructure, anti-aging properties, corrosion resistance, and robustness. MXene nanoparticles, labeled 25C and 80C, were synthesized using two different methods and incorporated at concentrations ranging from 0.1 to 2.0 wt.% into epoxy composites. The results demonstrated that 80C MXene, characterized by its finer morphology and superior dispersion, significantly improved the composite's performance compared to 25C. Electrochemical Impedance Spectroscopy (EIS) tests, along with long-term exposure assessments, suggested that incorporating both types of MXene nanoparticles enhances the corrosion protection performance of epoxy coatings over time. Micro-CT analysis revealed that both types of MXene substantially reduced defects and voids in the polymeric matrix, resulting in enhanced protective performance. This void reduction confirms that the incorporation of both 25C and 80C MXene improves microstructural integrity by filling voids and creating a more continuous, uniform structure, particularly in samples with 0.1% to 1.0% MXene flakes. The findings also highlighted MXene's potential in modifying the anti-aging properties of epoxy by inhibiting free radical generation and enhancing the composite's resistance against corrosion. Both 25C and 80C MXene-epoxy groups exhibited a clear trend of diminishing free radical intensity with increasing MXene concentration up to 1.0%, with free radical intensity reduced by over 40% compared to neat epoxy. The relationship between MXene concentration and reinforcement was also investigated, revealing superior corrosion protection properties at concentrations of 0.5-1.0 wt.%. This research offers a profound understanding of MXene's potential in polymer-based composites, laying a foundation for future investigations aimed at utilizing MXene to achieve superior material properties for a wide range of applications, particularly in the realm of metallic surface protection.more » « lessFree, publicly-accessible full text available September 1, 2025
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The occurrence of local buckling, an external anomaly in pipelines, significantly contributes to pipeline incidents, posing challenges in monitoring such localized anomalies, particularly during pipeline operations. This paper introduces an approach aimed at monitoring local buckling occurring in the compression bending area of pipeline sections. The proposed approach utilizes fiber Bragg gratings (FBGs) to facilitate real-time measurement of strain changes. Experimental tests were conducted on the steel pipe equipped with FBGs positioned near the top and bottom of the pipe, subjected to four-point loading test to generate bending and local buckling. The strain data obtained from FBGs enable effective detection and localization of bending and buckling deformations during the loading process. This research contributes to enhancing the capability to monitor external threats to pipelines, thereby fostering improved condition assessments and bolstering infrastructure resilience.more » « lessFree, publicly-accessible full text available June 1, 2025
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Structural integrity can be compromised by the simultaneous presence of mechanical loads and corrosive agents. This study investigates the complex interplay between corrosion and impact loads in steel plates, utilizing discrete Fiber Bragg Grating (FBG) and distributed Optical Frequency Domain Reflectometry (OFDR) sensing technology. Generalized fiber optic-based sensing models are developed to quantify corrosion severity and rate. The experimental study was conducted using twelve epoxy-coated steel plates equipped with FBG and OFDR sensors, covering scenarios of individual exposure to corrosion, impact loads, as well as their combination. Test results reveal that specimens subjected to combined conditioning exhibit more corrosion damage than those subjected to individual corrosion. Both pit depth and its growth rate were exacerbated due to the impact loads. The study demonstrates the potential of fiber optic sensors (FOSs) for real-time monitoring and assessment of structural health under different simultaneous multiple factors in challenging conditions.more » « lessFree, publicly-accessible full text available July 1, 2025
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Limongelli, Maria Pina ; Ng, Ching Tai ; Glisic, Branko (Ed.)Civil engineering structures are routinely exposed to corrosive environments, posing threats to their structural integrity. Traditional corrosion control methods often involve employing physical barriers, such as various coatings, to isolate the steel substrate from surrounding electrolytes. Among these methods, thermal spraying of alloy coatings has emerged as a prominent technique in safeguarding steel matrices against corrosion, particularly in industrial and marine settings. However, the inherent porosity of thermal spraying coatings compromises their corrosion resistance. Incorporating a polymer top layer offers a promising solution by sealing pores and augmenting overall performance. This study investigates corrosion on duplex-coated steel utilizing distributed fiber optic sensors based on optical frequency domain reflectometry. Experimental analyses involve embedding serpentine-arranged distributed fiber optic strain sensors within both thermal spraying layers and epoxy layers. Results demonstrate the efficiency of distributed sensors in identifying corrosion propagation paths by measuring the induced strain changes. Furthermore, the duplex coating exhibits significant enhancements in corrosion resistance for steel structures.more » « lessFree, publicly-accessible full text available May 9, 2025
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This study explored the enhancement potential of MXene, a novel two-dimensional material, in epoxy-based nanocomposites; which comprehensively examined the influence of MXene on epoxy's viscosity, void formation, aging resistance, mechanical properties, and anti-wear properties. MXene nanofillers, labeled as 25C and 80C, fabricated via different acid-etching methods, were incorporated into epoxy resin at varying weight percentages (0.1-2.0 wt.%). Observations revealed that for both varieties of MXene, inclusion of 1.0 wt.% MXene led to the mitigation of void content, whereas the incorporation of 2.0 wt.% MXene yielded maximal enhancements in both tensile strength and abrasion resistance. Additionally, the integration of 1.0 and 2.0 wt.% MXene displayed superior aging resistance, with around 80% reduction in free radical formation compared to the unmodified epoxy, while maintaining its excellent mechanical properties after QUV exposure. Therefore, both MXene types significantly enhanced the performance of epoxy composites, with the 80C-MXene displaying marginally superior enhancement due to its smaller particle size and higher purity, as identified by SEM and TEM images.more » « lessFree, publicly-accessible full text available March 1, 2025
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Sanders, Glen A. ; Lieberman, Robert A. ; Udd Scheel, Ingrid (Ed.)Each year, the global cost that is accounted to corrosion was estimated at $2.5 trillion. Corrosion not only imposes an economic burden, when corroded structures are under various loading conditions, it may also lead to structurally brittle failure, posing a potential threat to structural reliability and service safety. Although considerable studies investigated the combined effect of external loads and structural steel corrosion, many of the current findings on synergetic interaction between stress and corrosion are contrary. In this study, the combined effects of dynamic mechanical loads and corrosion on epoxy coated steel are investigated using the distributed fiber optic sensors based on optical frequency domain reflectometry. Experimental studies were performed using the serpentine-arranged distributed fiber optic strain sensors embedded inside the epoxy with three different scenarios including the impact loading-only, corrosion-only, and combined impact loading-corrosion tests. Test results demonstrated that the distributed fiber optic sensors can locate and detect the corrosion processing paths by measuring the induced strain changes. The combined impact loading-corrosion condition showed significantly accelerated corrosion progression caused by mechanical loads, indicating the significant interaction between dynamic mechanical loading and corrosion on epoxy coated steel.more » « less
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Fiber Bragg grating (FBG) sensors have been applied to assess strains, stresses, loads, corrosion, and temperature for structural health monitoring (SHM) of steel infrastructure, such as buildings, bridges, and pipelines. Since a single FBG sensor measures a particular parameter at a local spot, it is challenging to detect different types of anomalies and interactions of anomalies. This paper presents an approach to assess interactive anomalies caused by mechanical loading and corrosion on epoxy coated steel substrates using FBG sensors in real time. Experiments were performed by comparing the monitored center wavelength changes in the conditions with loading only, corrosion only, and simultaneous loading and corrosion. The theoretical and experimental results indicated that there were significant interactive influences between loading and corrosion for steel substrates. Loading accelerated the progress of corrosion for the epoxy coated steel substrate, especially when delamination in the epoxy coating was noticed. Through the real-time monitoring from the FBG sensors, the interactions between the anomalies induced by the loading and corrosion can be quantitatively evaluated through the corrosion depth and the loading contact length. These fundamental understandings of the interactions of different anomalies on steel structures can provide valuable information to engineers for better management of steel structures.more » « less
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Abstract Carbon‐based nanoparticles are widely regarded as promising nanofillers in nanocomposites to pursue advanced properties. To date, there has been a lack of systematic investigation into the structural variations of nanofillers and their influences on dispersion characteristics, as well as the resulting mechanical properties of nanocomposites. In this study, nanodiamond (ND), carbon nanotube (CNT), and graphene (GNP) were selected as the representative zero‐, one‐, and two‐dimensional nanofillers, respectively. A novel functionalization technique utilizing carboxymethyl cellulose (CMC) was employed to disperse nanofillers. The various characterization techniques and experimental results revealed that CMC functionalization was effective in reducing the agglomeration and improving the distribution uniformity of all three nanofillers. Among the three nanofillers, zero‐dimensional ND exhibited the most homogeneous dispersion quality in epoxy nanocomposites. The strongest abrasion resistance was found in ND‐reinforced epoxy nanocomposites, while CNT‐reinforced epoxy nanocomposites exhibited the best tensile properties.
Highlights Nanodiamond with a spherical structure had better dispersion characteristics.
Cylindrical carbon nanotube and planar graphene tended to agglomerate.
Nanodiamond reinforced nanocomposites had better abrasion resistance.
Carbon nanotube reinforced nanocomposites had better tensile properties.
Carboxymethyl cellulose functionalization was valid for all three nanofillers.
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This study presents an experimental investigation on the combined effect of mechanical loads and corrosion using the designed polytetrafluoroethylene tube-packaged fiber Bragg grating (FBG) sensors, as to implement long-gauge FBG (LFBG) sensors in corrosion detection practices for structural health monitoring. A simplified LFBG-based sensing model was proposed for strain measurement in terms of the Bragg wavelength change. Correspondingly, a systematic corrosion assessment strategy was developed to estimate corrosion severity and average corrosion rate. Upon this, the experimental study was performed on epoxy-coated steel specimens embedded with LFBG sensors, where the loading, corrosion, and combined loading–corrosion tests were used to explore the effect of mechanical loads on corrosion behavior. Test results revealed that the specimens subjected to combined conditions exhibited more severe corrosion damage. The maximum mass loss was observed to be 1.82 and 2.43 in percentage under individual corrosion and combined loading–corrosion conditions, respectively. Also, the pit depth under combined conditions was found to develop rapidly in the early stage. The pit depth severity ratio was around 0.2–0.8 during the 67 days of exposure, indicating an evident impact of loading on corrosion severity. Furthermore, the maximum average corrosion rate under combined conditions was found to be 5.66 times that under individual corrosion conditions.