Search Results (459)

Background/Objectives: Antiseptic gels applied at the implant–abutment interface (IAI) aim to reduce microbial leakage and peri-implant inflammation. However, introducing viscous media into a precision screw joint may affect tribology, preload maintenance, mechanical stability and corrosion-related processes. This scoping review mapped evidence on chlorhexidine (CHX) and other IAI gels, considering their biological, mechanical and electrochemical effects. Methods: Following PRISMA-ScR and a Population–Concept–Context framework, in vitro, in vivo and clinical studies of two-piece implant systems were eligible if they evaluated CHX or another sealing gel at the IAI and reported microbial, mechanical or electrochemical outcomes. English-language full texts published between 2015 and 2025 were identified through PubMed/MEDLINE, Scopus, ScienceDirect and reference screening. Findings were synthesised qualitatively within “Guardian” (biological protection) and “Hazard” (mechanical or electrochemical effects) domains. Results: Of 241 records, 16 met the inclusion criteria. CHX gels reduced intra-implant bacterial counts, although their sealing effect was limited and time-dependent. Silicone-based sealants generally achieved better microbial leakage control and, in several studies, maintained or increased reverse torque values compared with dry controls. Conversely, aqueous or oil-based antiseptic agents frequently reduced reverse torque, suggesting lubrication-related effects on screw-joint stability. No study directly quantified tribocorrosion associated with specific gels. Conclusions: IAI gels may provide biological protection, but their effects depend on formulation and are not exclusively antimicrobial. Silicone-based materials demonstrated the most favourable combined microbial and mechanical performance. Tribocorrosion remains insufficiently investigated, highlighting the need for integrated microbial, mechanical and electrochemical studies. Full article

This study evaluates the response of flame-retardant polypropylene composites after long-term exposure to aqueous and chemically aggressive media. Polypropylene (PP), used as a reference material, and PP-based composites containing 5, 10, 15, 20, and 25 wt.% of a phosphorus-based intumescent flame-retardant additive were immersed in water, NaCl solution, H₂SO₄ solution, and NaOH solution for up to 200 days. The material behavior was initially assessed by gravimetric measurements, based on the absorption/degradation degree calculated for early, mid, and late exposure intervals. This allowed the evolution of the material–medium interaction to be tracked not only by individual mass variations but also by average trends over the exposure period. The exposed systems were further investigated by thermogravimetric analysis (TGA/DTG) and dynamic mechanical analysis (DMA) to determine whether contact with the selected media modified the thermal degradation profile or the dynamic mechanical response of the composites. The results showed that the incorporated flame-retardant additive increases the interaction of PP with the liquid media, especially at intermediate and high additive contents. TGA/DTG and DMA confirmed that the thermal and viscoelastic behavior of the PP-based systems was maintained after long-term exposure, indicating that the observed medium-induced interactions did not result in substantial deterioration of their bulk thermo-mechanical properties. Full article

Cement mortar is widely used in buildings, roads, bridges, and other infrastructure. However, its inherent porous structure and hydrophilicity facilitate the penetration of water and aggressive media into the cement mortar matrix, accelerating rebar corrosion and compromising structural durability. The construction of superhydrophobic cement mortar surfaces can effectively improve water repellency, self-cleaning performance, antifouling performance, and corrosion resistance. However, existing superhydrophobic cement mortar surfaces have several limitations, such as complex fabrication processes, susceptibility to mechanical damage, and inadequate mechanical durability of surface coatings. To address these limitations, we propose a method for preparing superhydrophobic cement mortar that combines dry modification with stearic acid and template molding. Cement was hydrophobically modified with stearic acid, and a nylon mesh template was used to construct rough structures during cement mortar molding. The prepared superhydrophobic cement mortar exhibited excellent water repellency, self-cleaning performance, and antifouling properties, as well as good repellency to various water-soluble liquids. Moreover, the superhydrophobic surface retained good hydrophobicity after sandpaper abrasion and sand impact tests, indicating good mechanical stability. Furthermore, the superhydrophobic structure can effectively hinder the penetration of water and corrosive media into the cement matrix, improving the corrosion resistance of the cement mortar. The method features a simple fabrication process, avoids the use of fluorinated low-surface-energy agents, and offers tunability in surface appearance, providing a feasible route for preparing superhydrophobic cement mortar that integrates waterproofing, self-cleaning, antifouling, corrosion resistance, and decorative functions. Full article

Fe-Cr-B coatings were fabricated using laser-induction hybrid cladding and extreme high-speed laser-induction hybrid cladding (EHIC), and their microstructural evolution, dry friction performance, and tribocorrosion behavior were systematically investigated. The results indicate that the coatings consist of a matrix and eutectic region comprising M₂B and martensite. With increasing scanning speed, the coarse dendritic matrix transforms into an equiaxed structure, and the overall microstructure becomes significantly refined. The dry friction mechanisms of the Fe-Cr-B coating involve oxidation and abrasive wear. The eutectic region constitutes the primary load-bearing and wear-resistant constituent within the coating. Increasing its fraction directly enhances the overall wear performance. Furthermore, the formation of a tribolayer during testing contributes to improved wear resistance. These combined factors lead to a reduction in the wear rate from 99.7 × 10⁻³ mm³·N⁻¹·m⁻¹ to 50.2 × 10⁻³ mm³·N⁻¹·m⁻¹ as the scanning speed increases. In corrosive media, the formation of a tribolayer is hindered, and electrochemical corrosion diminishes the resistance of the coating to plastic deformation, leading to a substantial increase in the wear rate. Under these conditions, the wear mechanism transitions to one dominated by abrasive wear. Owing to the high fraction of the eutectic region in the EHIC coating, its tribocorrosion performance is superior. As the scanning speed increases, the wear rate decreases from 255.8 × 10⁻³ mm³·N⁻¹·m⁻¹ to 175.4 × 10⁻³ mm³·N⁻¹·m⁻¹. Full article

The increasing penetration of renewable energy requires coal-fired power plants to operate with greater flexibility, while deep load reduction and frequent load variations challenge combustion stability, efficiency, and equipment reliability. High-temperature solid-particle thermal energy storage (TES) offers a promising approach to decouple boiler heat supply from turbine power demand. This review compares particle heating, discharging, transport, and system-integration strategies and relates reported findings to key design and operational constraints. Solid-particle storage media can operate over a wide temperature range of approximately 200–1200 °C; silica sand can withstand temperatures up to about 1200 °C and alumina approximately 1100–1200 °C, substantially exceeding the typical operating range of nitrate molten salts (<600 °C). This broad temperature tolerance provides favorable thermal matching with high-temperature boiler flue gas. Direct flue-gas heating shortens the heat-transfer pathway and reduces intermediate heat-transfer stages, although its effects on boiler heat distribution and downstream heating surfaces require careful evaluation. Moving-bed discharging can provide continuous thermal output, while gravity-driven high-temperature transport combined with mechanical lifting after particle cooling can reduce the demand for high-temperature moving components. Based on these findings, a conceptual configuration integrating direct flue-gas heating, particle sensible-heat storage, moving-bed discharging, and temperature-segmented circulation is proposed. Future studies should focus on system-level efficiency, dynamic response, and load-following capability. Preliminary calculations for a 600 MW subcritical unit at 30% THA load show that particle-storage integration increases the boiler outlet flue-gas temperature by only about 1 °C, indicating no apparent increase in low-temperature corrosion risk under the investigated condition. Full article

Perfluorohexanone (C₆F₁₂O) has been widely utilized as an eco-friendly gaseous fire extinguishing agent. However, it is highly susceptible to thermal decomposition under high-temperature conditions during the fire protection process, generating substantial amounts of corrosive hydrogen fluoride (HF). To overcome the limitations of single-component suppression media, this study systematically investigates the effects of E-CF₃-CH=CClH addition on the thermal pyrolysis of the C₆F₁₂O agent, focusing on the evolution behaviors of fluorine-containing species and HF yield variation under various addition ratios and temperatures via a tube furnace. Additionally, ReaxFF-MD simulations were deployed to elucidate the microscopic pyrolysis fragment evolution and intermolecular interaction mechanisms within the blended system. The results indicate that the pyrolysis conversion of the blended suppressants across all mixing ratios increases monotonically with rising temperature. Once the C₆F₁₂O volume fraction surpasses 20% vol, chlorinated organic species completely disappear from the pyrolysis yield, accompanied by the detection of trace amounts of hydrofluoroalkanes. Additionally, maintaining the C₆F₁₂O content at 40% vol and 50% vol enables effective control over the net HF yield. Modeling reveals that blending predominantly enhances the C₆F₁₂O pyrolysis conversion during the early reaction phase. Mechanistically, HF mitigation within the binary network is governed by a multi-pathway synergistic mechanism. The insights gained from this work provide crucial theoretical foundations and empirical evidence for the formulation optimization of novel environmentally benign blended suppressants and the mitigation of secondary hazards in fire scenes. Full article

Graphene nanoplatelets (GNPs)-reinforced AlSi10Mg composites were fabricated by selective laser melting (SLM), and their corrosion resistance was systematically investigated as a function of GNPs content (0, 0.1, 0.3, and 0.5 wt.%) and corrosion duration. In the short term (≤30 days), the corrosion resistance followed the order: 0.1 wt.% GNPs/AlSi10Mg > 0.3 wt.% GNPs/AlSi10Mg > 0.5 wt.% GNPs/AlSi10Mg > AlSi10Mg. The 0.1 wt.% composite exhibited the best performance, attributed to the uniform dispersion of GNPs that filled micropores and microcracks to form a physical barrier against corrosive ions, along with favorable interfacial bonding that hindered crack growth and reduced corrosion pathways. After 60 days of exposure, however, the ranking reversed to: AlSi10Mg > 0.1 wt.% GNPs/AlSi10Mg > 0.3 wt.% GNPs/AlSi10Mg > 0.5 wt.% GNPs/AlSi10Mg. EIS analysis revealed a porous electrode behavior in the low-frequency response, captured by the constant phase element in the equivalent circuit. The long-term deterioration arose from the gradual penetration of corrosive media through micropores and microcracks, which triggered galvanic corrosion between GNPs and the matrix and rendered the barrier effect ineffective. These findings demonstrate that GNPs addition increases both the number and the total area of cathodic sites in the matrix alloy, thereby accelerating corrosion under prolonged exposure. In essence, GNPs serve as a protective barrier in the short term but transition to corrosion accelerators under long-term exposure. Full article

Heavy liquid metals such as liquid lead (Pb) are attractive heat transfer media for advanced energy applications, despite their corrosive nature. In the search for heat-resistant austenitic materials that are corrosion resistant to liquid Pb at high temperature, three new Fe24Ni15Cr3Al-based alumina-forming austenitic (AFA) steels with slightly varying compositions have been developed. The present study investigates the corrosion behavior of these AFA materials using static exposure tests to molten Pb containing 1 × 10⁻⁷ wt.% dissolved oxygen. The corrosion tests are performed at 500 °C, 600 °C, and 700 °C for 1000 h, 2000 h, and 5000 h each. In addition to the variation in material, temperature, and exposure time, two different surface finishes are also used for the tests. Examination of the specimens after exposure shows the formation of oxide scales for temperatures up to 600 °C on all three AFA materials, with minor material-specific variations. Furthermore, the scale characteristics depend on the surface finish. Coarse ground surfaces exhibit thin Al-rich protective oxide scales, while fine ground surfaces show the formation of thick multilayer oxide scales susceptible to Ni dissolution and Pb penetration. Pb exposure at 700 °C leads to a severe corrosion attack of all three Fe24Ni15Cr3Al-based AFA steels. Full article

Polytetrafluoroethylene/Polyetheretherketone (PTFE/PEEK) corrosion-resistant coatings were prepared on the surface of 7075 aluminum alloy by the electrostatic powder spraying technique (EPST). To achieve a denser microstructure and improved hydrophobic properties, we introduced nano-CeO₂ to fill the coatings and analyzed the mechanism of its effect on the different coating structures. The corrosion resistance of the coatings was evaluated using NaCl immersion. The results indicate that nano-CeO₂ enhances the coatings by filling local defects and forming a denser microstructural barrier, thereby improving the hydrophobicity and corrosion resistance of the composite coatings. Additionally, the addition of nano-CeO₂ to the 20 µm PTFE/PEEK composite coating increases structural heterogeneity and pore defects, reduces coating densification, and facilitates the penetration of corrosive media, thereby weakening the barrier capability of the coating. However, in the 50 µm PTFE/PEEK/CeO₂ composite coating, nano-CeO₂ particles fill part of the pre-existing defects and improve coating densification, thereby increasing the resistance to the penetration of corrosive media through the coating. This enhanced barrier effect delays the contact of corrosive media with the substrate and improves the corrosion resistance of the coating. In this study, the 50 μm PTFE/PEEK/CeO₂ composite coating with a nano-CeO₂ content of 0.5 wt.% exhibited the best corrosion resistance, with a corrosion current density of 8.02 × 10⁻⁴ μA·cm⁻², while |Z|_0.01Hz remained above 10⁶ Ω·cm² after 720 h of immersion in NaCl solution. Full article

The durability deterioration of concrete under the coupled action of freeze–thaw cycles and corrosive media is a critical technical challenge for engineering structures in cold regions and salt corrosive environments. This paper systematically reviews the research progress on the mechanical properties of concrete subjected to coupled freeze–thaw and corrosion effects. Starting from the mechanisms of freeze–thaw damage and corrosion damage, it analyzes the material degradation laws under individual factors and the synergistic failure mechanism of the coupled freeze–thaw–corrosion condition. The coupling effect is revealed: freeze–thaw-induced microcracks accelerate the penetration of corrosive media, while the expansion of corrosion products in turn aggravates freeze–thaw damage. Building on this, from the perspective of factors influencing concrete failure, this paper systematically summarizes the key factors governing concrete damage under single-factor and coupled-factor conditions as well as their nonlinear response characteristics. The review indicates that the damage degree under the coupled action is far greater than the simple superposition of damage caused by individual factors and presents complex patterns, including the concentration threshold effect, the time-sequence effect, and sensitivity to a low water–cement ratio. Existing reviews predominantly focus on qualitative descriptions of single-factor deterioration mechanisms, while systematic comparative analyses of threshold behaviors under multi-factor coupling and quantitative consolidation of mechanical degradation metrics remain limited. Furthermore, targeted durability design guidance tailored to cold saline environments is rarely summarized in the prior literature, which motivates the present comprehensive review. Although existing studies are relatively well-established for single damage mechanisms, further efforts are still needed to deepen the understanding of multi-factor interaction thresholds and dynamic evolution processes. The findings of this review can provide theoretical support and engineering reference for the durability design and service life prediction of concrete structures in cold regions and salt corrosive environments. The summarized threshold laws and quantitative mechanical degradation data can provide targeted parameter guidance for the durability design of hydraulic structures, bridge substructures, and port engineering in northwest saline soil, northern severe cold, and eastern coastal salt fog areas. Full article

Compared with traditional Al–Si die-cast alloys, which have good formability and low cost but poor brazeability and inadequate corrosion resistance, high-pressure die-cast (HPDC) Al–RE alloys exhibit superior comprehensive properties. To satisfy the demand for lightweight, high-performance materials in automotive thermal management, a controlled-atmosphere brazing (CAB) furnace was employed in this work to investigate the effect of the complete brazing cycle on the microstructure, mechanical properties, and corrosion resistance of the HPDC Al–RE alloy. In the as-cast state, the eutectic Al₁₁(La,Ce)₃ phase presents a lamellar structure. After the simulated brazing process, this phase transforms into dispersed near-spherical particles. Such microstructural evolution directly determines the mechanical and corrosion behaviors of the alloy. The yield strength and ultimate tensile strength decrease, while the elongation increases substantially owing to the alleviation of stress concentration. The corrosion resistance of the alloy depends on the service environment. After 960 h of neutral salt spray (NSS) testing, the alloy showed excellent corrosion resistance with only slight corrosion. Nevertheless, severe localized pitting corrosion (maximum pit depth: 0.932 mm) was observed after 480 h of sea water acidified accelerated test (SWAAT) exposure. This pitting phenomenon is directly associated with spheroidized Al₁₁(La,Ce)₃ particles. In acidic chloride-containing media, these intermetallic particles undergo preferential anodic dissolution relative to the α-Al matrix, resulting in micro-galvanic corrosion. In conclusion, after simulated brazing treatment, the ductility of the Al–RE alloy is remarkably improved at the cost of a moderate reduction in strength. The Al–RE alloy possesses good corrosion resistance in neutral saline environments. However, severe localized corrosion tends to occur in acidic environments due to the high electrochemical activity of spheroidized intermetallic phases. Full article

Autogenous shrinkage is a key factor contributing to early-stage cracking in high-performance concrete (HPC), which significantly affects structural durability and service life. As core components of HPC, supplementary cementitious materials (SCMs) can significantly improve concrete workability, mechanical properties, and durability, as well as reduce the risk of shrinkage cracking in HPC, by regulating hydration kinetics, pore structure, and microstructural evolution. The primary objective of this review is to elucidate the differential mechanisms by which different active pozzolanic materials regulate the autogenous shrinkage of HPC. This paper elucidates the patterns and mechanisms by which typical SCMs in HPC (such as fly ash, slag, silica fume, limestone powder, and nano-silica) affect the autogenous shrinkage of HPC. It analyzes the influence of key factors—including the type of SCMs, dosage, particle characteristics, water-to-binder (w/b) ratio, and composite blending on the autogenous shrinkage of HPC. Research indicates that highly reactive SCMs (such as silica fume and nano-silica) accelerate the self-drying process and increase autogenous shrinkage, whereas low-reactivity SCMs (such as fly ash) suppress autogenous shrinkage through dilution effects and by prolonging the hydration cycle. The combined use of multiple SCMs can achieve synergistic control of autogenous shrinkage and mechanical properties. Furthermore, this paper reviews existing autogenous shrinkage prediction models that account for the influence of SCMs and outlines future research directions. At the same time, this review identifies the limitations that currently exist in the research: there is a lack of a unified quantitative theoretical framework for the synergistic effects of multicomponent admixtures. The applicability of prediction models under multi-field coupling of temperature, humidity, and corrosive media is limited. And there is insufficient experimental data on the long-term shrinkage behavior of new low-carbon admixtures such as rice husk ash and calcined clay, which requires further dedicated research. Full article

Moisture significantly reduces the load-carrying capacity of lubricating oil films, accelerates oxidative degradation, and induces equipment corrosion, making it a critical hazard factor affecting lubrication reliability. To overcome the limitations of existing methods for determining water content—such as complex operation, poor real-time performance, and high cost—this paper proposes a radio frequency identification (RFID)-based method for lubricating oil water content detection via the orthogonal fusion of phase and received signal strength indicator (RSSI) as an off-line analytical tool. The method exploits the signal variation characteristics when RF signals penetrate media with different dielectric properties; by analyzing the phase and RSSI of backscattered RFID signals, non-contact moisture sensing is achieved. First, a theoretical model integrating phase and RSSI for water content detection is established to reveal the differential response mechanisms of the two parameters to water content. Second, a detection method based on phase-RSSI orthogonal fusion is proposed, and performance evaluation metrics are constructed. Finally, comparative experiments with different detection approaches are conducted. It is found that as water content increases, the mean phase continuously rises with significantly increased fluctuation, while RSSI exhibits a linear decreasing trend, demonstrating clear complementary response characteristics. Compared with single-phase or single-RSSI methods, the proposed fusion method achieves a coefficient of determination (R²) of 0.95 over the 0–2.0% water content range, with reliable detection verified at concentrations as low as 0.1%, and exhibits superior detection sensitivity in the low-water-content range. Furthermore, it possesses a type-discrimination capability absent in single-parameter methods—that is, it can effectively distinguish whether response variations originate from moisture contamination or non-moisture interference. The method offers stable response and high detection efficiency, providing a new approach for accurate determination of water content in lubricating oil. Full article

Methanol compression-ignition engines are vital for transport carbon neutrality, yet methanol’s low cetane number, corrosivity, low viscosity, and cavitation tendency compromised piezoelectric injector reliability. This study proposed systematic optimization strategies tailored to methanol’s fuel properties. A sealed thin-walled metal encapsulation, fabricated from precipitation-hardening martensitic stainless steel, was designed to isolate corrosive methanol media. The geometry of the tubular spring was optimized to meet the stiffness requirements for high-frequency injections. A monolithic nozzle without side pin holes, also upgraded to the same precipitation-hardening martensitic stainless steel, effectively suppressed stress corrosion cracking by leveraging the material’s combined high strength and excellent corrosion resistance. A dedicated return-line backpressure valve compensated for hydraulic leakage and improved fuel replenishment, and nozzle hole taper and inlet fillet radius were optimized to mitigate cavitation. Cold-motoring reliability tests showed the optimized injector maintained flow deviation within 3% after 100 million cycles, whereas the unoptimized prototype reached 8% deviation at 60 million cycles. The single-cycle injected fuel quantity coefficient of variation dropped from 4% to 1.3%. Spray characteristic comparison tests further confirmed that the optimized injector maintained stable flow consistency and atomization quality after prolonged cyclic operation. These optimizations effectively resolved corrosion, wear, and hydraulic instability caused by methanol, significantly enhancing flow consistency and durability over the service life. The results provided critical component-level technical support for advancing methanol compression-ignition engines from laboratory research to industrial application, addressing key reliability barriers that previously hindered engineering deployment of methanol-fueled powertrains. Full article

A novel orthophosphate compound, BaNb_0.5In_0.5(PO₄)₂ (FA31), was investigated as a corrosion inhibitor for mild steel in 1.0 M HCl using electrochemical techniques, adsorption studies, and surface characterization. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) measurements demonstrated that the inhibition efficiency increased with inhibitor concentration, reaching a maximum value of 94.8% at the optimal concentration. The charge-transfer resistance (Rct) increased significantly from that of the uninhibited solution to 427.2 Ω·cm² in the presence of FA31, indicating the formation of a protective interfacial layer that effectively suppressed the corrosion process. The adsorption of FA31 on the mild steel surface followed the Langmuir adsorption isotherm, while the calculated standard Gibbs free energy of adsorption (ΔG°ads) indicated that the inhibition process was predominantly governed by physisorption. SEM/EDS analyses further confirmed the formation of a compact and homogeneous protective film on the steel surface. The combined electrochemical and surface analyses demonstrate that FA31 is an effective and environmentally promising corrosion inhibitor for mild steel in acidic media. Full article