Search Results (319)

Copper and its alloys are indispensable for electronics, communications, new energy systems, and aerospace engineering due to their exceptional electrical conductivity and mechanical properties. However, the thin cuprous oxide (Cu₂O) layer that naturally forms on copper and its alloys is prone to failure under elevated temperatures and high humidity, particularly in chloride-rich environments, leading to accelerated localized corrosion. While conventional chromate-based passivation has long been the industrial standard for preventing corrosion, its use has been increasingly restricted by global regulations (such as RoHS and REACH) due to its severe toxicity and health risks. To address the conflict between environmental compliance and protective performance, this review systematically evaluates recent advances in environmentally friendly, chromium-free anti-corrosion coatings in the present review. These alternative coatings are critically analyzed and categorized into four mechanistic groups: (i) inorganic conversion coatings (including molybdate, tungstate, rare earth, and phosphate systems); (ii) organic films formed via chemical or physical adsorption (such as organic inhibitors, thiol-based monolayers, and organosilane self-assembled films); (iii) conversion coatings engineered through covalent bonding, coordination chemistry, and microstructural tailoring; and (iv) multifunctional coatings that integrate self-healing capability with high electrical conductivity. Beyond providing a technical summary, this review explored how the swift progression of electronic information technology, new energy infrastructure, and robotics has imposed more exacting, multifunctional demands on copper components. This review provides a strategic roadmap for future research and prioritizes the creation of protection strategies that operate robustly in multi-physics coupling environments—integrating high conductivity, autonomous self-healing, and long-term chemical stability to ensure the reliability of next-generation infrastructure. Full article

Recently, gel coatings have been studied as a promising method that can provide electrochemical corrosion protection. This review presents a comprehensive analysis of advanced gels such as sol–gel coatings, hybrid organic–inorganic, self-healing, and crack repair gels. These gels employ different mechanisms for corrosion protection, from passive barrier formation to active self-healing and corrosion inhibition. Their performance can be influenced by gel chemistry, microstructure, and the incorporation of functional additives. Recent studies have shown that gel coatings can achieve promising corrosion resistance. This high efficiency can be attributed to the formation of dense barrier layers that restrict the mobility of attacking ions. The incorporation of functional additives such as silica nanoparticles can enhance mechanical characteristics for gels. In the field of crack-repair, bio-gels based on microbially induced calcium carbonate precipitation show acceptable sealing capability. Additionally, the evolution of polarization resistance and corrosion current suggests the sustained protective performance of these gels. Multifunctional gels extend this concept by combining crack sealing, alkalinity restoration, and steel re-passivation. Gel coatings are transitioning from simple barrier coatings to multifunctional smart inhibition capable of self-healing, corrosion sensing, and long-term durability. This review highlights the relationship between gel chemistry, microstructure, and corrosion resistance for the development of next-generation gel coatings. Full article

Extending the service life of asphalt pavement and cutting maintenance costs are two reasons self-healing technologies have drawn growing attention. Based on 66 studies published between 2011 and 2026, this review covers four engineered self-healing technologies: induction heating, microwave heating, microcapsule-based healing, and microbial-induced calcium carbonate precipitation (MICP). Quantitative comparisons are made for the first three; microbial healing is discussed separately because only four studies were found. Induction heating has been tested in the field and can reach healing efficiencies of up to 96.5% (maximum reported value). Microcapsule-based healing has a reported peak efficiency that approached 100% under optimal conditions, but can only be used once. Microwave heating heats more evenly across the pavement depth but has not been tested in the field. Microbial healing is at an early stage, with modest strength recovery (UCS, unconfined compressive strength, up to 47%). This review argues that evaluation fragmentation—the use of different indicators, test conditions, and material formulations across studies—makes it difficult to compare technologies and hinders field use. A standardized dual-index evaluation framework is proposed, along with three research priorities: adopting standardized protocols, monitoring existing field trials over the long term, and conducting full life-cycle cost analysis. Full article

Cracks pose a significant threat to the structural integrity, durability, and service life of concrete; therefore, sustainable, autonomous repair solutions are paramount. In the last 25 years, bio-based self-healing, particularly microbially induced calcium carbonate precipitation (MICP), has become an attractive technology. Self-healing by bacteria has been studied extensively, but the use of other biomineralization agents, such as fungi and algae, has unique benefits, namely, hyphal crack-bridging and photosynthetic mineralization. In this paper, a thorough state-of-the-art review is presented that compares bacteria, fungi, and algae as biomineralization agents. The comparative methodology involves a structured review of the peer-reviewed literature on these agents (2000–2025), and compares them on a set of common performance criteria: (i) biochemical precipitation mechanisms (ureolytic, non-ureolytic, photosynthetic and hyphal bridging); (ii) quantitative crack-healing efficiency (maximum width of crack closed); (iii) mechanical performance recovery (restoration of compressive and tensile strength); (iv) long-term durability enhancement. Moreover, it critically evaluates implementation challenges, including biological viability in extreme cementitious media, encapsulation methods, and the levels of technological maturity for practical engineering applications. The findings of this synthesis outline key research gaps and offer a roadmap for creating hybrid, consortium-based self-healing systems to help engineers and researchers select the best bio-based concrete for a given structure and environment. Full article

This review provides an overview of the latest advances in bionic vascular self-healing cement, focusing on vascular design, fabrication, selection of healing agents, transport and curing mechanisms, and performance evaluation methods. Compared to systems based on microcapsules and microorganisms, vascular networks enable directed and efficient transport of healing agents and repeated healing; however, the presence of hollow channels results in an inevitable loss of mechanical properties. Additive manufacturing, in situ printing based on Pickering emulsions, and direct printing of cement-based or multi-material systems have enhanced geometric flexibility and scalability. However, issues such as channel quality, polymer-cement interface stability, and on-site quality control remain unclear. Regarding the selection of healing agents, epoxy resin systems are generally more suitable for structural healing, polyurethanes are suitable for rapid sealing and wide or irregular cracks, while silicate healing agents are suitable for healing where cement compatibility and durability are prioritized. The most critical research gap lies in the lack of standardized, full-scale, multi-cycle, and long-term environmental validation, which limits the practical engineering application of vascular self-healing technology. Future research should prioritize the integrated design of various performance metrics, the long-term durability of polymers, standardized benchmark testing, and validation based on actual service conditions. Full article

Polybenzoxazines (PBz) represent a versatile class of high-performance thermosetting polymers that have attracted significant attention for advanced composite applications due to their unique combination of properties including high glass transition temperatures, low polymerization shrinkage, excellent thermal stability, and molecular design flexibility. This comprehensive review examines the structure–property relationships governing PBz composite performance, from molecular design principles through network formation, composite reinforcement strategies, and ultimate application performance. The review systematically addresses benzoxazine monomer structure and its influence on polymer network architecture, explores the polymerization mechanism, and critically evaluates composite design strategies incorporating carbon-based nanofillers, fiber reinforcements, and hybrid filler systems. Detailed analysis of structure–property relationships reveals how molecular and composite architecture control thermal stability (glass transition temperatures exceeding 350 °C and char yields up to 92%), mechanical performance, electrical properties (dielectric constants as low as 2.67), and chemical durability. Processing techniques ranging from conventional compression molding to emerging additive manufacturing approaches are discussed in the context of morphological control and property optimization. Applications spanning aerospace structures, high-frequency electronics and protective coatings demonstrate the technological relevance of PBz composites. Critical challenges including network brittleness, high cure temperatures, and recyclability limitations are addressed alongside recent advances in dynamic covalent networks, vitrimer chemistry, and self-healing systems that promise to overcome these barriers. This review provides a comprehensive framework for understanding and engineering polybenzoxazine composites for next-generation advanced applications. Full article

The von Neumann architecture, due to the physical separation between memory and processor, has limited the development of data-intensive applications. Neuromorphic computing technologies inspired by the brain’s parallel and event-driven operation mechanisms have enabled low-power in-memory computing. Memristors with tunable conductance can emulate biological synapses, while flexible memristors further offer mechanical flexibility, making them suitable for wearable electronics and intelligent sensing systems. This review systematically summarizes the switching mechanisms of flexible neuromorphic memristors, including conductive filaments, interface effects, ferroelectricity, phase change, and multiple synergistic mechanisms. It categorically discusses natural and bio-derived materials, synthetic organic/polymer materials, and inorganic functional materials, and introduces strategies for enhancing flexibility. The article also covers device architectures such as sandwich structures, crossbar arrays, and fiber-based textile structures, along with low-temperature fabrication techniques. Finally, it reviews recent advances in neuromorphic computing, in-memory computing, biomimetic sensing, and biomedical wearable systems. Challenges related to mechanical stability and device uniformity are analyzed, and future directions toward self-healing materials and integrated sensing-storage-computing systems are outlined. This comprehensive review bridges the gap between material innovation and system-level integration in flexible neuromorphic memristors, providing a valuable roadmap for accelerating the development of next-generation wearable artificial intelligence, edge computing, and bio-integrated electronic technologies. Full article

Carbon-based materials, including graphene, carbon nanotubes, laser-induced graphene, and pyrolyzed glassy carbon, are widely used in sensing applications due to their high conductivity, large surface area, and tunable surface chemistry. Meanwhile, microfluidic systems enable precise fluid handling, reduced sample consumption, and enhanced analytical performance through improved mass transport and device miniaturization. The integration of carbon-based materials with microfluidic platforms has enabled the development of compact, portable, and highly sensitive devices for water monitoring. This review summarizes recent advances in carbon-based microfluidic sensors for water monitoring applications. Key carbon materials and their sensing mechanisms, particularly electrochemical transduction, are discussed. Various microfluidic integration strategies, including paper-based devices, polymer-based devices, MEMS-based systems, and flexible platforms, are highlighted, with emphasis on mass transport enhancement and overall system performance. Representative recent advances in carbon-based microfluidic sensors for water monitoring, including the detection of heavy metal ions, nutrients, and emerging contaminants, are reviewed. Finally, challenges related to scalable manufacturing, long-term operational stability, biofouling/surface fouling, and reproducible system integration are discussed, together with future perspectives on intelligent carbon-based microfluidic platforms featuring AI-assisted analytics, sense-response functionality, and self-healing and dynamic antifouling capabilities for water monitoring. These advances are expected to enable real-time, low-cost, and field-deployable water monitoring systems for environmental protection and public health management. Overall, this review highlights the critical role of integrating carbon-based sensing materials with microfluidic engineering in advancing next-generation water monitoring technologies. Full article

Gallium (Ga)-based liquid metal (LM) composites, particularly those based on eutectic gallium–indium (EGaIn) and related alloys, have emerged as a promising materials platform for soft and deformable energy storage owing to their unique combination of metallic conductivity, fluidic deformability, and adaptive interfaces. Despite rapid advances in LM-enabled devices, binders remain insufficiently understood and are still commonly regarded as passive structural components. Here, we present a comprehensive binder-centered perspective for LM composites, establishing the binder as a key regulator of electro-chemo-mechanical coupling, interfacial stability, transport behavior, and processability in soft energy systems. We show that tailored binder chemistries in Ga-based LM systems—including stretchable batteries, printable conductors, and soft electrochemical devices—govern LM droplet dispersion, suppress coalescence and leakage, and preserve conductive percolation under large deformation, while enabling room-temperature fabrication and printability through rheological regulation and interfacial wetting. Beyond mechanical confinement, emerging binder functionalities—including dynamic bonding, supramolecular interactions, ionically conductive networks, and reversible polymer architectures—enable self-healing interfaces, adaptive transport pathways, and robust adhesion in deformable devices. By integrating recent advances in stretchable batteries, flexible supercapacitors, printable electronics, and multifunctional soft energy systems, we establish a unified multiscale framework linking binder molecular design to device-level electrochemical and mechanical performance. We further discuss sustainability and manufacturing considerations, including recyclable polymer networks, low-temperature fabrication, and scalable processing strategies. Finally, we outline current challenges and future opportunities toward programmable binder systems with tunable viscoelasticity, interfacial reactivity, and adaptive functionality. This Review establishes binder-centered engineering as a key pathway for transforming LM composites from proof-of-concept materials into resilient, manufacturable, and multifunctional soft energy technologies for wearable, stretchable, and biointegrated electronics. Full article

Corrosion-protective coatings have progressed from passive barrier systems and chromate-based technologies toward multifunctional materials that integrate barrier durability, interfacial adhesion, active inhibition, electrochemical response, and self-healing capabilities. However, the intellectual framework connecting these technological developments remains fragmented, as most reviews focus on specific material families rather than on the broader evolution of the field. This study examines technological paradigms in corrosion-protective coatings through a citation network analysis of highly cited publications retrieved from Web of Science and processed with CitNetExplorer. The most influential publications were thematically reviewed to identify dominant materials, coating architectures, protection mechanisms, seminal contributions, and bridge articles. Four principal paradigms were identified: smart and self-healing coatings based on nanocontainers, layered double hydroxides, mesoporous silica, halloysite, zeolites, hydroxyapatite reservoirs, and microcapsules; chromate-free sol–gel and silane pretreatments based on organic–inorganic hybrid matrices, organosilanes, rare-earth inhibitors, and oxide nanoparticles; graphene and graphene oxide-based nanocomposite coatings in which two-dimensional fillers enhance tortuosity, reduce water uptake, and reinforce polymer matrices and coating–substrate interfaces; and electroactive coatings based mainly on polyaniline and polypyrrole, where protection is associated with passivation, redox mediation, and dopant-controlled inhibition. The findings indicate that corrosion-protective coatings have evolved through partially overlapping and increasingly integrated paradigms rather than through a single technological trajectory. This citation network analysis clarifies the transition from chromate replacement toward active, nanostructured, electroactive, and self-healing corrosion-protective systems. Full article

Although microbial self-healing concrete technology has been widely studied, limited attention has been paid to the effect of the dosage of microbial self-healing materials on concrete crack repair performance. To address this, this study investigates the influence of the dosage of microbial self-healing materials on the crack repair performance of concrete using planar thin-plate specimens. The results are summarized as follows: (1) Increasing the dosage of microbial self-healing materials effectively delays the initial cracking time of concrete specimens. When the dosage levels were 10%, 20%, and 30%, the initial cracking time was prolonged by 50%, 65%, and 70%, respectively, compared with the blank group without microbial addition. (2) After 28 d of water spraying and coating curing, the total crack area of concrete decreased significantly compared with that at the early age (1 d). For dosages of 0%, 10%, 20%, and 30% of microbial self-healing materials, the total crack area per unit surface area decreased by 12.2%, 21.9%, 22.7%, and 31.8%, respectively, compared with the initial stage. (3) Through X-ray diffraction (XRD), thermogravimetric analysis (TG/DTG), and morphological characterization, the presence of microbial mineralization products, including calcite and vaterite, on the concrete crack surfaces was confirmed. Full article

This study presents a comprehensive analysis of self-healing concrete technologies, focusing on autogenous and autonomous self-healing methods, through a systematic literature review of peer-reviewed articles. The autogenous self-healing method relies on the natural hydration and carbonation processes of unhydrated cement particles, enhanced by additives such as fly ash, slag, and superabsorbent polymers. It is effective for small cracks (<200 μm), environmentally favorable, and cost-efficient, although it is limited by relatively slow healing rates and reduced performance over time. The autonomous self-healing method incorporates external agents, primarily bacteria like Bacillus cohnii and Bacillus sphaericus, encapsulated in protective carriers. These bacteria precipitate calcium carbonate (CaCO₃) upon activation, sealing cracks up to approximately 1240 μm. While generally more effective in terms of healing efficiency and durability, the autonomous self-healing method involves higher production costs. Life cycle assessment results indicate that the autonomous self-healing concrete can exhibit up to 85% higher environmental impact during the production phase than conventional concrete. However, during the production phase, the autogenous self-healing method shows about 32% higher CO₂ emissions than the autonomous method. Results from investigating the mechanisms, performance, repairability, environmental impacts, and economic aspects in this study demonstrate that bacterial concentration and nutrient type critically influence mechanical properties, with optimal strength gains at 10⁵ cells/mL. Both techniques reduce corrosion risk and extend service life, with the autonomous self-healing method displaying superior performance in harsh environments. However, the autogenous self-healing method is more feasible for large-scale applications due to lower costs and simpler implementation. The study concludes that method selection should align with project-specific durability, sustainability, and economic goals. Full article

Microbial-induced calcite precipitation (MICP) and enzyme-induced calcite precipitation (EICP) have emerged as research hotspots in recent years at the intersection of geotechnical engineering, environmental engineering, and materials engineering. Compared with traditional grouting reinforcement and repair methods, these methods exhibit greater environmental benignity, higher calcium carbonate precipitation yield, and more significant improvement in mechanical properties of repaired materials. The urease activity in the urease-based MICP and EICP techniques lies at the core of rock fracture repair, soil reinforcement, and concrete crack remediation. This paper presents a systematic review of urease-based MICP and EICP repair technologies, focusing on repair principles, environmental influencing factors, research methods, and application approaches, including microbial cultivation, enzyme activity determination, preparation of cementing solutions, selection of carriers, injection methods, and repair cycles. It also compares the advantages and disadvantages of MICP and EICP. This review clarifies the intrinsic similarities and differences between the two technologies in mineralization mechanism, crystal characteristics and engineering applicability, and constructs a complete technical system of urease-based biomineralization. Additionally, this paper discusses current macroscopic and microscopic evaluation methods for biomineralization repair effects, synthesizes existing mineralization repair systems, and assesses the challenges of self-healing biomaterials, including long-term microbial durability, repair strength stability, and the overall cost of widespread application. It includes long-term microbial durability, repair strength stability, enzyme activity retention, and the overall cost of widespread application, which are key issues to be solved for engineering implementation. The aim of this study is to provide a theoretical and practical reference for the theoretical improvement and engineering application of EICP and MICP technologies. Full article

Background/Objectives: The aim of this study was to compare the augmentation stability and clinical outcomes of L-shaped collagenated soft block bone substitutes (BBS) used in combination with either a self-assembly technology (SAT)-based physically crosslinked resorbable collagen membrane (RCM) or a conventional non-crosslinked RCM for peri-implant dehiscence defects. Methods: This retrospective cohort study included 30 patients who underwent guided bone regeneration (GBR) with simultaneous implant placement. The patients were treated with either a physically crosslinked membrane (PCM group, n = 15) or a non-crosslinked membrane (NCM group, n = 15). Clinical, radiographic, and profilometric parameters were evaluated at baseline, immediately post-GBR, and at re-entry surgery. Early wound healing complications and patient-reported outcomes were also assessed. Results: Both groups achieved significant defect resolution without severe adverse events. The mean reductions in defect width and height were 4.47 ± 1.82 mm (92.9%) and 4.07 ± 2.19 mm (89.4%) in the PCM group and 3.80 ± 1.59 mm (89.5%) and 4.13 ± 1.64 mm (86.9%) in the NCM group, respectively. Both groups showed comparable dimensional changes in hard and soft tissues, with no statistically significant differences in radiographic or profilometric outcomes. The incidence of wound healing complications, as well as patient-reported postoperative pain and swelling, were similar between the groups. Conclusions: Within the limitations of this retrospective pilot cohort study, SAT-based physically crosslinked RCMs used in combination with L-shaped soft BBS demonstrated clinical, radiographic, profilometric, and patient-reported outcomes similar to those observed with conventional non-crosslinked RCMs, without major short-term postoperative complications. These preliminary findings suggest that SAT-based RCMs may represent a feasible membrane option for GBR; however, these findings should be interpreted as preliminary and hypothesis-generating and should be confirmed in larger, adequately powered prospective clinical studies. Full article

Asphalt pavements are prone to the formation of microcracks due to aging under environmental factors, and microcapsule-based self-healing technology represents an effective means of preventive maintenance. In this study, corn oil, a renewable and environmentally friendly material, was selected as the asphalt rejuvenator to prepare corn oil microcapsules via in situ polymerization, and the self-healing performance of corn oil microcapsule-modified asphalt was investigated. By analyzing the effects of corn oil microcapsules on the high-temperature performance, salt resistance, chemical structure, and microscopic morphology of asphalt, as well as the influence of temperature, time, and corn oil microcapsule content on the self-healing performance of asphalt mixtures, the self-healing mechanism of corn oil microcapsule-modified asphalt was elucidated at both the microscopic and macroscopic levels. The results showed that during the preparation of corn oil microcapsules, the optimal molar ratio of M_F:M_(M+U) was 2.5, with an emulsification rate of 1.2 kr/min. The prepared corn oil microcapsules exhibited high yield and good encapsulation efficiency, possessed excellent high-temperature resistance that met the requirements of the asphalt mixing stage, and showed superior salt resistance. FTIR analysis confirmed the successful incorporation of microcapsules into the asphalt system. Atomic force microscopy (AFM) observations revealed that the microcapsules mitigated microscopic surface damage caused by aging. The healing index of the asphalt mixtures incorporating corn oil microcapsules increased with prolonged healing time and elevated temperature. By establishing the relationship between the healing index and the content of corn oil microcapsules, the recommended content of corn oil microcapsules within the tested range is 6 wt%. This study elucidates the self-healing mechanism of corn oil microcapsule-modified asphalt from both microscopic (surface parameter recovery) and macroscopic (mechanical property restoration) scales, providing a scientific basis for the application of microcapsule technology in green and sustainable asphalt pavement maintenance. Full article