Prolonged Service Research Articles

Evolution of Microstructural and Mechanical Properties of Alloy 617B During Service on a Key-Component Test Platform at 700 °C

The evolution of the microstructural and mechanical properties of alloy 617B during long-term service on a key-component test platform at 700 °C was systematically investigated. The precipitation behavior and size changes of the M23C6 and γ′ phases were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that carbide M23C6 precipitated in the form of discontinuous particles, plates, or needles at grain boundaries and within grains, while the γ′ phase had a spherical shape and was distributed in a dispersed manner. With prolonged service time, both the M23C6 and γ′ phases gradually coarsened. After 24,000 h of service, the yield strength, tensile strength, and Brinell hardness of alloy 617B significantly increased; however, the impact toughness decreased, accompanied by intergranular embrittlement. The increase in precipitate volume fraction and its contribution to the strength of the alloy were evaluated by a precipitation strengthening model. The coarsening of M23C6 was identified as the main cause of embrittlement. The findings of this study provide important experimental data and theoretical support for the stability of 617B alloys under long-term high-temperature service conditions.

Microstructural Evolution of P92 Steel with Different Creep Life Consumptions After Long-Term Service

P92 steel is widely used in ultra-supercritical units due to its excellent high-temperature performance. This paper studies the microstructure of P92 steel steam pipes in three conditions: as-supplied, after 80,000 h of service at 67.06 MPa stress, and after 100,000 h of service at 80.28 MPa stress. After prolonged service, the P92 steel retains its martensitic structure, but the lath width increases and the dislocation density decreases. In addition to M23C6, MX, and Laves phases, Z phase was also observed among the precipitates. The results indicate that the sizes of M23C6 and Laves phases increase with the progression of creep life consumption, with the coarsening rate of Laves phase being significantly higher than that of M23C6. However, the coarsening of MX phase is not evident. Compared to the Laves phase, the formation of the Z phase requires a longer period of time. The precipitation of the Z phase consumes MX carbonitrides, and it has been observed that the Z phase precipitates from the MX phase, with the two phases exhibiting a coexisting state.

An active learning framework assisted development of corrosion risk assessment strategies for offshore pipelines

Aggressive fluids and prolonged service life result in an increasing internal corrosion risk of offshore pipelines, especially for perforation. A framework was constructed by active learning (AL) aimed at assessing the future corrosion risk of offshore pipelines and rapidly developing in-line inspection (ILI) strategies. Compared with Support Vector Regression (SVR), K-Nearest Neighbors (KNN) and Random Forest (RF), the Gradient Boosting Regression (GBR) model exhibits greater robustness and stability under both 10-fold cross-validation (CV) and bootstrap method. The RMSE and R2 are 1.48 and 0.83, respectively. Through the double iterative operation of input parameters and models, the AL framework can significantly reduce the demand for training samples, while maintaining accurate predictions. This study contributes to promoting the application of active learning methods in pipeline integrity management and planning, and providing assistance for the construction of intelligent and digital oilfields.

Hydrodynamic Flexible Spindle (HydroFlex) Polishing of turbine blade internal cooling channels for oxide removal

Internal cooling channels are essential to turbine blades for high efficiency power generation. Effective removal of aluminum oxide build-up in turbine blade cooling channels is of critical importance to refurbishment and prolonged service life of turbine blades. Conventional internal polishing processes, including abrasive flow machining, chemical polishing, and electrical discharge machining cannot effectively remove the oxide layer within the internal cooling channels due to the complex geometry with high aspect ratio and diameter variation and the electric insulation of the oxide layer. In this case study, we investigated the application of a novel hydrodynamic flexible-spindle (HydroFlex) polishing process to remove the oxide layer within the internal cooling channels of an Inconel 738 turbine blade that was taken out of serve due to oxide build-up. For a 350 mm long cooling channel featured with an inner diameter transition from ϕ4 mm to ϕ2.5 mm, within 12 min, at the grinding wheel rotational speed of 50,000 rpm and 30,000 rpm, HydroFlex was able to completely remove the 14.31 µm thick oxide layer off from the wall of the turbine blade internal cooling channel, improve the channel circularity by 54.7 %, and decrease the channel surface roughness by up to 64.3 %. The results demonstrated the effectiveness of HydroFlex in polishing complex internal cooling channels of turbine blades for oxide removal and potential blade service life extension.

Predicting time to cracking of concrete composites under restrained shrinkage: A review with insights from statistical analysis and ensemble machine learning approaches

Restrained shrinkage cracking significantly undermines the performance of reinforced concrete and shortens the structures' lifespan. Standard methods have been established to examine restrained shrinkage cracking of cementitious composites, i.e., ASTM C1581, AASHTO T 334, AASHTO T 363, and RILEM TC 119-TCE. Deficiencies in testing methods for accommodating and evaluating different cementitious composites have been recognized. Nevertheless, the significance of the restrained shrinkage cracking factors and cracking vulnerability based on the degree of restraint provided by different testing methods remain unexplored. This article provides a critical review of testing methods and studies on restrained shrinkage cracking in cementitious composites, highlighting the limitations, advantages, and further capabilities. Comprehensive experimental test datasets associated with standard restrained shrinkage cracking test methods are compiled. Advanced statistical analysis and machine learning (ML) techniques are utilized to predict time-to-cracking (TTC) of cementitious composites subjected to various testing methods based on the cracking factors. Robust and precise ML's bagging and boosting algorithms such as random forest, gradient boosting machine, extreme gradient boosting, adaptive boosting, categorical gradient boosting, and stacking ensemble models are utilized to merge predictions of the various approaches on TTC. Despite the satisfactory performance of statistical modeling, stacking demonstrates the highest precision in forecasting TTC, achieving an R2 of 0.92 for the ASTM dataset and 0.65 for the AASHTO dataset. The derived statistical and ML models reveal the significance of drying shrinkage, binder content, and moist curing as the most important factors in TTC based on ASTM C1581 and AASHTO T 334 standard testing methods. Equations are derived to predict cracking vulnerability and design concrete composites that offer delayed TTC and prolonged service life.

METHODS OF TREATMENT OF RETAINED PLACENTA IN FRIESIAN COWS

Retained placenta in dairy cows is when the fetal membrane or placenta does not exit the uterus within 9-12 hours after calving. Retained placenta is a pathological disorder when the placenta does not fall out within a certain period of time after calving. The placenta in cows is most often expelled 6 (77.3%) to 8 hours after calving (Van Werven et al., 1992). The incidence of placental abruption in cows averages 8.6%. The cause of placental exit is not fully understood. There are several factors on which the separation of the fetal placenta from the uterus depends, they can be: genetic (inherited), nutritional, immunological, and as a result of some diseases of the reproductive tract. The causes of placental retention can be: fatigue of the uterus, inflammatory conditions of the bed, an insufficient amount of some hormones, lack of vitamins and/or minerals, toxic effects of some substances and poisons, and mechanical obstacles. The conclusion is that cows with retained placenta belong to the risk group because they are prone to inflammation of the uterus, so they have a prolonged service period and delayed or absent recovery of the cyclic activity of the ovaries, which can be the cause of sterility, temporary or permanent. Treatment of retained placenta should be carried out in time, removing the fetal placenta manually and inserting foaming tablets for intrauterine use. After that, PgF2α and oxytocin are applied.

Influence of connection design and material properties on stress distribution and fatigue lifetime of zygomatic implants: A finite element analysis

Zygomatic implants (ZIs) were developed as a graftless alternative to rehabilitate severely reabsorbed maxillae. This study aims to employ three-dimensional finite element analysis (FEA) to simulate the impact of external hexagonal implant connection (EHC) and internal hexagonal implant connection (IHC) on the stress distribution and fatigue lifetime within the ZI systems using parameters defined in ISO 14801:2016. Two ZI assemblies (Nobel Biocare and Noris Medical) were scanned in a micro-CT scanner and reconstructed using Nrecon software. Three-dimensional models were generated by Simpleware ScanIP Medical software. All models were exported to FEA software (ABAQUS) and subsequently to a fatigue analysis software (Fe-safe). A compressive 150 N load was applied at a 40° angle on the cap surface. A 15 Hz frequency was applied in the in silico cyclic test. The implant components had material properties of commercially pure grade 4 titanium (CPTi) and Titanium-6Aluminum-4Vanadium alloy (Ti64). Von Mises stress data, contour plots, and fatigue limits were collected and analyzed. EHC models exhibited higher peak stresses in implant components for both materials compared to IHC models. However, simulated bone support results showed the opposite trend, with higher stresses on IHCthan EHC models. The fatigue analysis revealed that assemblies with both designs exceeded ISO 14801:2016 number of cycles limits using Ti64, while CPTi groups exhibited comparatively lower worst life-repeats. In conclusion, ZIs with IHC were found to have a more homogeneous and advantageous stress distribution within both materials tested. Ti64 demonstrates a prolonged service life for both design connections.

Bilayer nested porous microcapsules inspired by honeycomb structures achieving efficient self-healing and intrinsic property enhancement of insulating materials

Self-healing microcapsules represent a highly promising strategy for enhancing the long-term durability of materials under prolonged service conditions. Nevertheless, the industrial application of microcapsules encounters significant challenges. This is primarily due to the dilemmas involved in guaranteeing effective repair without significantly undermining the intrinsic properties of the substrate materials. Inspired by the structure of honeycombs, this paper introduces a bilayer, nested, porous self-healing microcapsule featuring an ultra-thin, rigid shell that effectively addresses the above challenges. An ultra-thin rigid shell is first constructed to enhance mechanical strength while significantly increasing the load capacity of the healing agent. Subsequently, the subcritical water treatment method is employed to etch nanoscale through-holes on the shell surface for encapsulating the healing agent. Finally, via a cross-linking reaction, a film is formed on the surface of the porous shell to seal the holes. The test results show that the loading efficiency of the microcapsules achieves 94.4 %. Moreover, while the repair efficiency is substantially enhanced, the intrinsic properties of the matrix material are maintained, and there is additionally a measurable improvement in tensile strength and insulation performance. To our knowledge, the microcapsules that significantly enhance repair efficiency while concurrently improving the properties of the matrix have not yet been reported in previous studies.

Organizational resiliency through practice innovation: forced brand evolution in a prolonged exogenous service ecosystem disruption

PurposeThis paper aims to explore practice innovation and organizational resiliency during exogenous service ecosystem disruptions. This inquiry focuses on the extreme disruption caused by the COVID-19 pandemic, which required service firms to recodify long-established service scripts, adapt digital and physical material elements of the service encounter and ultimately reconfigure a system of practices. The specific context is forced practice innovation in Starbucks servicescape (kiosks and coffeehouses). Starbucks is best known for its custom beverages and third-place strategy. Their strict adherence to a complex service script and unique ordering practices altered during pandemic stay-home disease prevention mandates.Design/methodology/approachThematic coding consistent with prior research on practice innovation and diffusion and a grounded theory methodology was conducted. Data were triangulated and analyzed within and across a variety of sources. These include field notes from direct observation, interviews, focus groups, firm-authored collateral in the form of marketing communications and third-party authored secondary sources such as news, social media, blogs and forums.FindingsData reveal how practice innovation occurs through the reconfiguration of a system of practices, which support organizational resiliency and can force brand evolution, in prolonged exogenous service ecosystem disruptions. The COVID-19 pandemic required service industries to adapt and recodify service scripts and alter physical and digital elements of service encounters. While the pandemic affected all firms in the sector, we argue that Starbucks' established scripts and third-place strategies, which characterized the brand experience, were particularly vulnerable. We find that practice innovation occurs through the reconfiguration of practice elements – competences, meanings and materiality – and restructures the service encounter. Practice codification, transposition, adaptation and stabilization support organizational resiliency and brand evolution. We find that Starbucks' brand experience emphasis on the third place is reconceptualized from an in-person community-based retailscape to a platform-based strategy necessitating script recodification and practice adaptation. Our analysis of Starbucks' kiosks and coffeehouses illuminates how a distinctly branded service encounter is constituted by a system of practices that can be reconfigured and diffused anew in the face of disruption.Originality/valueThe conceptualization of practice innovation as systems reconfiguration establishes a novel approach to understanding innovation in service ecosystems. The COVID-19 pandemic is a unique context to study a sector-wide exogenous extended service disruption. We focus on a firm with an elaborate pre-pandemic service script and commitment to a third-place brand experience guiding its system of practices. We reveal unique insights on practice innovation within service ecosystems during exogenous prolonged disruptions in which brands evolve through the recodification of service scripts and sustained reconfiguration of systems of practice.

A model of contact deep groove seals based on partition model and JFO boundary condition

Unlike nuclear main pump seals, deep groove seals in aero-engines operate on a contact basis. However, the precise working mechanism and accurate quantitative methods for assessing their sealing performance remain elusive. This paper introduces a fluid-solid-thermal coupling model for contact deep groove seals, utilizing a partition model and considering JFO boundary condition, mixed lubrication, and detailed heat calculations. The model significantly enhances accuracy compared to original approaches. It comprehensively accounts for contact effects, thermal deformations, convergence wedges, radial waviness, hydrodynamic pressures, groove drainage, and convection, revealing characteristics of contact deep groove seals such as high stiffness, effective heat dissipation, wear resistance, and prolonged service life. The proposed model and working mechanism provide theoretical guidance for designing diverse deep groove seal structures.

Highly tough, crack‐resistant and self‐healable piezo‐ionic skin enabled by dynamic hard domains with mechanosensitive ionic channel

AbstractRobust and reliable piezo‐ionic materials that are both crack resistant and self‐healable like biological skin hold great promise for applications inflexible electronics and intelligent systems with prolonged service lives. However, such a combination of high toughness, superior crack resistance, autonomous self‐healing and effective control of ion dynamics is rarely seen in artificial iontronic skin because these features are seemingly incompatible in materials design. Here, we resolve this perennial mismatch through a molecularly engineered strategy of implanting carboxyl‐functionalized groups into the dynamic hard domain structure of synthesized poly(urethane‐urea). This design provides an ultra‐high fracture energy of 211.27 kJ m−2 that is over 123.54 times that of tough human skin, while maintaining skin‐like stretchability, elasticity, and autonomous self‐healing with a 96.40% healing efficiency. Moreover, the carboxyl anion group allows the dynamic confinement of ionic fluids though electrostatic interaction, thereby ensuring a remarkable pressure sensitivity of 7.03 kPa−1 for the tactile sensors. As such, we successfully demonstrated the enormous potential ability of this skin‐like piezo‐ionic sensor for biomedical monitoring and robotic item identification, which indicates promising future uses in flexible electronics and human–machine interactions.

Exploring Musculoskeletal Injuries Among Informal and Formal Carers of People With Dementia.

Carers of people with dementia manually handle the care recipients (eg, repetitive lifting, transferring, and pulling) as part of the care service, increasing the musculoskeletal injury risk to themselves. We aimed to determine the prevalence of musculoskeletal injuries among informal and formal carers of people with dementia and the perceived associated risk factors. Primary carers of people with dementia (26 males and 141 females) from Dementia Care Centers and Home Care programs completed a questionnaire providing information about (a) the carers' and their care recipients' characteristics, (b) musculoskeletal symptoms (via the Nordic Musculoskeletal Questionnaire) and related aspects, and (c) the caregiving activities exposing the carers to risk of musculoskeletal injury. Our results showed that 69.7% of informal and 86.7% of formal carers reported having more than 1 musculoskeletal injury, while 63.1% and 61.5%, respectively, reported having a musculoskeletal injury in the last year. Lower back had the highest injury prevalence (>10% for both groups). The 2 carer groups were not different in any of the variables. Our results reinforce calls for education and support of carers, regardless of their formal status, to enable injury-free and prolonged service provision.

Design and molecular dynamics of biocompatible WPU/PVA composite hydrogels with enhanced fatigue resistance: Energy dissipation of intermolecular clusters for elastomers

To engineer a hydrogel elastomer for use as an in vivo tissue replacement, it is imperative to ensure superior fatigue resistance, guaranteeing a prolonged service life. Investigating the molecular mechanisms of strain energy accumulation and transmission, which occur during the compression of elastomeric materials, is instrumental in elucidating the causes of hydrogel material fatigue. Such insights are of immense value for the development of durable artificial tissue replacements, ensuring their longevity and sustained functionality within the human body. We synthesized hydrogel elastomers through polyvinyl alcohol (PVA) and waterborne polyurethane (WPU) with good biocompatibility, and studied their fatigue behavior through molecular dynamics (MD). The results of this analysis demonstrate that the introduction of energy dissipation structures between mechanically supported molecular frameworks can enhance the relaxation efficiency of polymers. This improvement leads to enhanced resistance of hydrogels to compression fatigue. A total of 1,000,000 cycles of compression tests were conducted to verify that WPU/PVA did not exhibit any significant compression fatigue under high stress of 50 % strain. In contrast, PVA hydrogel exhibited obvious fatigue due to the absence of an energy dissipation structure. These results revealed the source of compression fatigue resistance of hydrogel elasticity and provided powerful guidance for the design and synthesis of artificial tissues.

Kenaf/glass fiber‐reinforced polymer composites: Pioneering sustainable materials with enhanced mechanical and tribological properties

AbstractHybrid kenaf/glass fiber reinforced polymer composites have emerged as promising structural materials, garnering significant attention due to their unique blend of natural kenaf fibers and synthetic glass fibers. However, despite their potential, there remains a gap in the comprehensive understanding of their quasi‐static mechanical behavior, creep resistance, and fatigue performance. This paper addresses this gap by presenting recent advancements in studying these key properties of hybrid composites. Studies reveal that the combination of kenaf and glass fibers results in enhanced tensile, flexural, and impact strengths compared to individual fiber composites. Additionally, the hybridization offers improved creep resistance, with the glass fibers reinforcing the polymer matrix against deformation under sustained loads. Furthermore, investigations into fatigue properties demonstrate the resilience of hybrid composites to cyclic loading, contributing to prolonged service life in high‐stress environments. By elucidating the interplay between kenaf and glass fibers, this review underscores the potential of hybrid composites in various structural applications. The synergistic effects between natural and synthetic fibers offer a balance between sustainability, performance, and durability, making hybrid kenaf/glass fiber reinforced polymer composites a compelling choice for industries seeking lightweight, high‐performance materials in which aligns with the sustainable development goals (SDGs) especially on Goal 12.Highlights In composite engineering, combining glass and kenaf fibers could cut production costs, yield high‐performance materials, and promote green technology. Substituting part of the glass fiber with kenaf can enhance the strength‐to‐weight ratio and promote greater biodegradability in current synthetic composites. Quasi‐mechanical properties of hybrid kenaf/glass‐based composites was enhanced by optimal stacking sequences, filler addition, and fiber treatment. Failures due to fatigue and creep can be reduced by hybridizing kenaf/glass fiber composites can prevent in polymer composite due to enhance elastic modulus. Enhanced tribological performance of hybrid kenaf/glass‐based composites due to less damage in microstructure via good interlocking of kenaf and glass in matrix.

A Water Environment-Based Simulated Method for Ultrasonic Testing of Slag Inclusion Weld Defects Based on Improved VMD.

The identification of slag inclusion defects in welds is of the utmost importance in guaranteeing the integrity, safety, and prolonged service life of welded structures. Most research focuses on different kinds of weld defects, but branch research on categories of slag inclusion material is limited and critical for safeguarding the quality of engineering and the well-being of personnel. To address this issue, we design a simulated method using ultrasonic testing to identify the inclusion of material categories in austenitic stainless steel. It is based on a simulated experiment in a water environment, and six categories of cubic specimens, including four metallic and two non-metallic materials, are selected to simulate the slag materials of the inclusion defects. Variational mode decomposition optimized by particle swarm optimization is employed for ultrasonic signals denoising. Moreover, the phase spectrum of the denoised signal is utilized to extract the phase characteristic of the echo signal from the water-slag specimen interface. The experimental results show that our method has the characteristics of appropriate decomposition and good denoising performance. Compared with famous signal denoising algorithms, the proposed method extracted the lowest number of intrinsic mode functions from the echo signal with the highest signal-to-noise ratio and lowest normalized cross-correlation among all of the comparative algorithms in signal denoising of weld slag inclusion defects. Finally, the phase spectrum can ascertain whether the slag inclusion is a thicker or thinner medium compared with the weld base material based on the half-wave loss existing or not in the echo signal phase.

Numerical simulation and experimental study of three-phase distribution characteristics of leaked light non-aqueous phase liquid from buried pipelines in soils containing groundwater and gas.

Leakage accidents of buried pipelines have become increasingly common due to the prolonged service of some pipelines which have been in use for more than 150years. Therefore, there is an urgent need for accurate prediction of pollution scope to aid in the development of emergency remediation strategies. This study investigated the distribution of a light non-aqueous phase liquid in soils containing gas and water through numerical simulations and laboratory experiments. Firstly, a three-dimensional porous medium model was established using ANSYS FLUENT, and for the first time, the distribution of gas and groundwater in soil environments was simulated in the model. Subsequently, the distribution of the three phases of diesel, gas, and water in soil was studied with different leakage velocities and it was found that the leakage velocity played a significant role in the distribution. The areas of diesel in soils at 60min were 0.112m2, 0.194m2, 0.217m2, and 0.252m2, with corresponding volumes of 0.028m3, 0.070m3, 0.086m3, and 0.106m3, respectively, for leakage velocities of 1.3m/s, 3.4m/s, 4.6m/s, and 4.9m/s. Calculation formulas for distribution areas and volumes were also developed to aid in future prevention and control strategies under different leakage velocities. The study also compared the distribution areas and volumes of diesel in soils with and without groundwater, and it was found that distribution scopes were larger in soils containing groundwater due to capillary force. In order to validate the accuracy of the numerical simulation, laboratory experiments were conducted to study the diffusion of oil, gas, and water under different leakage velocities. The results showed good agreement between the experiments and the simulations. The research findings are of great significance for preventing soil pollution and provide a theoretical basis for developing scientifically sound soil remediation strategies.

Comparative investigation on the tribocorrosion resistance of Ti6Al4V and 60NiTi alloys inimulated seawater environment

The Ti6Al4V alloy is extensively utilized in critical marine equipment components due to its low density, high specific strength, and exceptional corrosion resistance in marine environments. However, its low hardness and inadequate wear resistance pose challenges in meeting the urgent demand for prolonged service life of relative motion friction pairs under complex wear and corrosion conditions. As a newly developed lightweight friction pair material, hardened 60NiTi is considered highly desirable owing to its combination of high hardness, high compressive strength, and excellent corrosion resistance. Nevertheless, the tribocorrosion properties of 60NiTi compared to those of Ti6Al4V are not yet fully comprehended. The present study conducted a series of sliding wear tests using a ball-on-plate configuration in artificial seawater environment to compare the response of 60NiTi with Ti6Al4V. In order to gain a comprehensive understanding of the factors contributing to the divergence in tribocorrosion response between both materials, further analysis was performed on the wear track subsurface and transfer film using focused ion beam-scanning electron microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy respectively. The 60NiTi demonstrates significantly enhanced wear resistance in artificial seawater compared to Ti6Al4V, attributed to its combination of high hardness and excellent corrosion resistance. However, Ti6Al4V exhibits a lower friction coefficient (∼0.30) than 60NiTi (∼0.45) due to the formation of a stable transfer film primarily composed of SiO2, Al(OH)3, and Al2O3.

Replacement of Fault Sensor of Cutter Suction Dredger Mud Pump Based on MCNN Transformer

The mud pump water sealing system (MPWSS) is important in the efficient operation and prolonged service life of the cutter suction dredger’s (CSD) mud pump. Considering that the underwater pump operates underwater and the shaft seal water pressure sensor is prone to failure, a hybrid deep learning model MCNN transformer is proposed to predict the underwater pump shaft seal water pressure in the event of sensor failure. This paper uses big data from the dredging project to deeply excavate the relationship between the shaft end sealing water pressure and other construction data by combining experience and artificial intelligence, and then uses multi-scale convolutional neural network (MCNN) to reconstruct the data, highlighting the time series characteristics of the multi-scale data were then input into the transformer model for prediction, and compared with a single MCNN, transformer model and four other neural networks. Finally, the cutter suction dredger “Hua An Long” was selected as an application research case; experimental comparisons were conducted on seven different models to verify the accuracy and applicability of the MCNN-transformer model.

Electrodeposited ZIF-67 reinforced polypyrrole coating on ferritic stainless steel substrate with durable anticorrosion performance

The harsh acidic environment containing chloride ions has created serious corrosion hazards for ferritic stainless steels. Zeolitic imidazole frameworks (ZIFs) are a promising material for corrosion protection due to their microstructural and physicochemical properties. In this study, we proposed the electrodeposited ZIF-67 reinforced polypyrrole (PPY) coating (PPY/ZIF-67) for corrosion protection of 430 ferritic stainless steel (430SS). The morphology, microstructure, and anticorrosion behavior of the pristine PPY and hybrid PPY/ZIF-67 coating systems were characterized. The successful electrodeposition of ZIF-67 nanoparticles on the surface of the PPY layer resulted in a uniform distribution and a compact coating structure, which contributed to the overall uniformity of the coating and enhanced both the barrier and activity inhibition functions of the coating. The protective performance of PPY/ZIF-67 coatings was evaluated through electrochemical tests, the results indicated that the anticorrosion efficiency of PPY/ZIF-67 coating (with 0.4 mol/L pyrrole monomer content) reached to 99 %, and the coating demonstrated a durable corrosion protection ability (744 h) in 0.1 mol/L HCl solution. Such performance of can be attributed to the combined effect of the anodic protection provided by the inner PPY film, the active corrosion inhibiting properties of the ZIF-67 nanoparticle layer, and the hindrance of aggressive species by the compact coating structure over the prolonged service time.

A novel sensor based on the composite mechanism of magnetic flux leakage and magnetic field disturbance for comprehensive inspection of defects with varying angles and widths

Ferromagnetic components are susceptible to various defects after prolonged service. The defects generated in these components are diverse and exhibit irregular orientation, which may impede comprehensive defect examination using a single magnetic testing method. This paper proposes a novel magnetic measurement sensor that integrates the principles of magnetic flux leakage (MFL) and magnetic field disturbance (MFD). The combined theory is analyzed and validated through the utilization of finite element method (FEM) simulations as well as experimental investigations. By comparing simulation results with experimental data, the composite nature of the signal acquired beneath a magnetic bridge is convincingly demonstrated. In comparison to conventional MFL and MFD methods, this innovative sensor exhibits superior defect detection performance for varying angles and widths, while also addressing some inherent limitations associated with MFL and MFD principles.