Zn-Cu alloys have attracted great attention as biodegradable alloys owing to their excellent mechanical properties and biocompatibility, with corrosion characteristics being crucial for their suitability for biomedical applications. However, the unresolved identification of intermetallic compounds in Zn-Cu alloys affecting corrosion and the complexity of the application environment hamper the understanding of their electrochemical behavior. Utilizing high-throughput first-principles calculations and machine-learning accelerated evolutionary algorithms for screening the most stable compounds in Zn-Cu systems, a dataset encompassing the formation energy of 2033 compounds is generated. It reveals that most of the experimentally reported Zn-Cu compounds can be replicated, especially the structure of R32 CuZn5 is first discovered which possesses the lowest formation energy of -0.050 eV per atom. Furthermore, the simulated X-ray diffraction pattern matches perfectly with the experimental ones. By formulating 342 potential electrochemical reactions based on the binary compounds, the Pourbaix diagrams for Zn-Cu alloys are constructed to clarify the fundamental competition between different phases and ions. The calculated equilibrium potential of CuZn5 is higher than that of Zn through the forward reaction Zn + CuZn5 reversible arrow CuZn5 + Zn2+ + 2e(-), resulting in microcell formation owing to the stronger charge density localization in Zn compared to CuZn5. The presence of chlorine accelerates the corrosion of Zn through the reaction Zn + CuZn5 + 6Cl(-) + 6H(2)O reversible arrow Cu + 6ZnOHCl + 6H(+) + 12e(-), where the formation of ZnOHCl disrupts the ZnO passive film and expands the corrosion pH range from 9.2 to 8.8. Our findings reveal an accurate quantitative corrosion mechanism for Zn-Cu alloys, providing an effective pathway to investigate the corrosion resistance of biodegradable alloys.

This study investigates the hot compression behavior of a molybdenum- Rhenium (Mo-Re) alloy, focusing on deformation mechanisms and instability. Utilizing electron backscattered diffraction (EBSD) and transmission electron microscope (TEM), we characterized the microstructure, grain orientation, and deformation behavior across temperatures (650, 750, 850, and 950 degrees C) and strain rates (0.01, 0.1, 1, and 10s-1). The study reveals that Mo-Re alloys exhibit high hot deformation resistance, necessitating optimal processing conditions for effective plastic deformation. Key findings by EBSD and TEM include the formation of dislocation networks and substructures enhancing grain plasticity. We established a constitutive equation and processing maps, providing valuable insights for industrial applications and future alloy development.

By employing laser cladding, the surface of a ferritic/martensite (F/M) steel was coated with FeCrAl metallic and FeCrAl/TiC composite coatings with their microstructures and wear resistance subjected to dedicated characterizations. The thickness of the FeCrAl coating is -90 mu m with its microstructure mainly consisting of coarse columnar grains. In contrast, the FeCrAl/TiC coating is primarily comprised of fine equiaxed grains with a thickness of -140 mu m. It is demonstrated that the addition of TiC could lead to very effective grain refinement, promote their morphology to transform from columnar to equiaxed, and suppress cracks in the coating. Both the laser-clad specimens have a heat-affected zone with 35-40 mu m in thickness and mainly comprised of martensitic laths. During the martensitic transformation, the obedience of specific orientation relations (Nishiyama-Wassermann and Kurdjumov-Sachs) produces scattered orientations and featured misorientation characteristics. Wear tests show that both the coatings have greatly reduced wear rates compared with the substrate, and characterizations of their worn tracks suggest all of them to essentially have abrasive and oxidative wear mechanisms. Compared with the FeCrAl metallic coating, the wear resistance of the FeCrAl/TiC composite coating is further considerably improved due largely to the TiC-induced grain refinement.

The compatibility of cladding material with lead-bismuth eutectic (LBE) above 600 °C poses a critical challenge in the implementation of lead-bismuth fast-cooled stacks. Consequently, we fabricated three coatings of Al + Al 2 O 3 , FeAl, and FeAl + Al 2 O 3 using ferritic/martensitic steel as the substrate through multi-arc ion plating. We evaluated the microstructure and hardness of the substrate and coatings, in addition to exploring the samples' corrosion resistance through static LBE corrosion at 600 °C for 1000 hours. Our findings indicate that all three coatings exhibited exceptional corrosion resistance under high-temperature lead-bismuth, and the thickness of the oxide layer formed by corrosion was reduced by 60 pct in comparison to that of the uncoated sample. The oxide layer was composed of Fe 3 O 4 , Al 2 O 3 , and FeCr 2 O 4 . During the corrosion process, lead-bismuth infiltrated the oxide layer through the pores, leading to oxidation of the inner fresh coating, while the outer oxide layer underwent crack expansion with pores at the core.

In this work, two oxide-reinforced FeCrAl matrix composite coatings, FeCrAl-Al2O3 and FeCrAl-Y2O3, were fabricated on a ferritic-martensitic steel by laser cladding with their microstructures probed by means of multiple characterization methods. Their cross-sections are found to consist of three zones with distinct microstructure features, i.e. cladding zone (CZ), heat-affected zone (HAZ) and substrate. Their CZs are mainly composed of columnar ferrite (the average grain sizes 7.1 +/- 3.9 mu m and 6.5 +/- 3.8 mu m for the FeCrAl-Al2O3 and the FeCrAl-Y2O3 coatings, respectively), with plenty of O-rich particles dispersed in-side the ferrite. For the HAZs, they are essentially comprised of markedly refined martensitic laths. The average surface hardnesses of the FeCrAl-Al2O3 and the FeCrAl-Y2O3 coatings are 357.1 +/- 8.7 HV and 348.4 +/- 26.1 HV, respectively, notably higher than the substrate (264.7 +/- 2.7 HV). Such effective hard-ening is attributed to the combined effect of solid-solution and dispersion strengthening. The wear rates of the FeCrAl-Al2O3 and the FeCrAl-Y2O3 coatings are 37% and 73% lower than the substrate, respectively, demonstrating considerably enhanced wear resistance. After characterizing the worn surfaces, abrasive wear and oxidative wear are confirmed to occur on all the specimens during the wear test. The en-hanced wear resistance of both the composite coatings should mainly be related to the high hardnesses produced by their specific microstructural features, and the easier formation of surface oxide films during the wear.(c) 2023 Elsevier B.V. All rights reserved.

Al2O3 coatings are the most promising candidate material for mitigating (lead-bismuth eutectic) LBE corrosion at elevated temperatures, but preventing inward diffusion of Pb, Bi, and O for the ceramic coating remains a critical challenge. Here, we have fabricated an amorphous Al2O3 coating with an ultra-dense structure by continuous high-power magnetron sputtering (C-HPMS). After LBE corrosion at 550 °C for 2000 h, nanocavities induced by the phase transformation from amorphous to γ-Al2O3 provide the diffusion path for Fe, O, Pb, and Bi in which the corrosion products, such as Fe3O4, PbO2, or their mixed oxides, form. Furthermore, the diffusion of Pb to the substrate and Cr segregation at the interface between the coating and substrate are observed for the sample exposed to LBE at 550 °C for 4000 h. Additionally, the hardness and interface bonding strength are enhanced after LBE corrosion. Moreover, pit corrosion was found to be the main failure mode of coating, and pits that merged with each other induced large area failure at a temperature of 650 °C. The corrosion mechanism of Al2O3 includes element diffusion, phase transformation, and chemical reaction. This work not only provides a deep understanding of the corrosion mechanism of amorphous Al2O3 coatings, but also shows the optimization method on the corrosion resistance of Al2O3 coating.

Aluminide coating is a promising candidate material to prevent the LBE corrosion on structural materials in Generation IV lead-based reactor. However, the corrosion resistance and its failure mechanism remain a longstanding challenge. Here, we synthesis an amorphous Al2O3 coating via radio frequency magnetron sputtering (RFMS). Corrosion pits are observed at the macro scale on the coated substrate after LBE corrosion at 550 degrees C for 2000 h, because of the consumption of ferritic/-martensitic (F/M) steel caused by oxidation. In particular, the volume expansion of corrosion nodules while covered by the Al2O3 coating is investigated. Furthermore, calculation results demonstrate that the concentration of Pri-stress in corrosion products induced coating failure. A model based on corrosion morphology and related properties is proposed to illustrate the stress distribution of corrosion nodules and the further failure mechanism of coatings. This work not only provides a deep understanding on the failure mechanism of brittle ceramic coating, but also paves the way for designing highperformance coatings in reactor.

High temperature coatings possess great potential for improving operation temperature of 4th generation nuclear reactor. In this paper, a high-entropy alloy nitride coatings (CrAlTiNbV)N x were investigated for the application in corrosive lead-bismuth alloy (LBE). The coatings were synthesized by unbalanced magnetron sputtering on ferritic/martensitic (F/M) steel. Properties of (CrAlTiNbV)N x are systematically investigated from perspective of the electron structure, crystalline, and mechanical properties under different bias voltage applied on samples. Significant improvement of hardness (30 GPa) is obtained at bias voltage of -156 V. Furthermore, the corrosion behavior in 550 degrees C lead bismuth eutectic (LBE) was conducted for 1200 h with saturated oxygen content, which demonstrates the dense structure of coatings with no obvious crack, spallation that characterized by the SEM, EDS, and TEM. Upon the application of high bias voltage, more prone formation of high-density grain boundary with fine grains extends the diffusion path of Pb and Bi are achieved for excellent LBE corrosion resistance. Our work not only provide an insight to the electron structure of high entropy alloy nitrides, but also shows a potential application for (CrAlTiNbV)N x protecting fuel cladding in the next generation lead based reactor. (c) 2022 Elsevier B.V. All rights reserved.

A typical ferritic/martensitic (F/M) steel sheet was subjected to pulsed laser surface remelting (LSR) and corrosion test in lead-bismuth eutectic (LBE) at 550 °C. There present two modification zones with distinct microstructures in the LSRed specimen: (1) remelted zone (RZ) consisting of both bulk δ-ferrite grains and martensitic plates and (2) heat-affected zone (HAZ) below the RZ, mainly composed of martensitic plates and high-density precipitates. Martensitic transformation occurs in both the RZ and the HAZ with the Kurdjumov-Sachs and Nishiyama-Wassermann orientation relationships followed concurrently, resulting in scattered orientations and specific misorientation characteristics. Hardnesses of the RZ and the HAZ are 364 ± 7 HV and 451 ± 15 HV, respectively, considerably higher than that of the matrix (267 ± 3 HV). In oxygen-saturated and oxygen-depleted LBE, thicknesses of oxide layers developed on both the as-received and the LSRed specimens increase with prolonging corrosion time (oxide layers always thinner under the oxygen-depleted condition). The corrosion resistance of the LSRed F/M steel in oxygen-saturated LBE is improved, which can be attributed to the grain-refinement accelerated formation of dense Fe–Cr spinel. In oxygen-depleted LBE, the growth of oxide layers is very low with both types of specimens showing similar corrosion resistance.

Liquid metal fast reactors were considered to be the most promising solution to meet the enormous energy demand in the future. However, corrosion phenomenon caused by the liquid metal, especially in high-temperature lead-bismuth coolant, has greatly hindered the commercialization of the advanced Generation-IV nuclear system. This review discussed current research on the corrosion resistance of structural materials (such as EP823, T91, ODS, and authentic steels) in high-temperature liquid metal served as reactor coolants. The current corrosion resistance evaluation has proved that even for the excellent performance of EP823, the structural material selected in pressurized water reactor is not the ideal material for operation in the high-temperature lead-bismuth eutectic (LBE). Furthermore, the latest coating technologies that are expected to be applied to cladding materials for coolant system were extensively discussed, including Al-containing coatings, ceramic coatings, oxide coatings, amorphous coatings and high-entropy alloy coatings. The detailed comparison summarized the corrosion morphology and corrosion products of various coatings in LBE. This review not only provided a systematic understanding of the corrosion phenomena, but also demonstrated that coating technology is an effective method to solve the corrosion issues of the advanced next-generation reactors.

Dielectric material selection coupled with surface-charge engineering is demonstrated to effectively improve the output performance of triboelectric nanogenerators in a high humidity environment.

Vibration sensor is very necessary for monitoring the structural health of constructions. However, it is still a major challenge to meet simultaneously real-time monitoring, continuous assessment, and early incident warning in a simple device without a complicated power and analysis system. Here, we report a self-powered vibration sensor system to achieve real-time and continuous detection of the vibration characteristics from a dual-mode triboelectric nanogenerator (AC/DC-TENG), which can produce either alternating current (AC) or direct current (DC) within different operation zones. Within the vibration-safe region, the AC/DC-TENG with AC output not only can continuously assess the vibration characteristics but also can power the signal transmission. More importantly, once the vibration amplitude crosses the danger threshold, the AC converts immediately to DC, meanwhile triggering the alarm system directly to accurately predict the danger of construction. Our self-powered vibration sensor system can serve as a facile tool for accurately monitoring the structural health of constructions.

An ocean wave contains various marine information, but it is generally difficult to obtain the high-precision quantification to meet the needs of ocean development and utilization. Here, we report a self-powered and high-performance triboelectric ocean-wave spectrum sensor (TOSS) fabricated using a tubular triboelectric nanogenerator (TENG) and hollow ball buoy, which not only can adapt to the measurement of ocean surface water waves in any direction but also can eliminate the influence of seawater on the performance of the sensor. Based on the high-sensitivity advantage of TENG, an ultrahigh sensitivity of 2530 mV mm(-1) (which is 100 times higher than that of previous work) and a minimal monitoring error of 0.1% are achieved in monitoring wave height and wave period, respectively. Importantly, six basic ocean-wave parameters (wave height, wave period, wave frequency, wave velocity, wavelength, and wave steepness), wave velocity spectrum, and mechanical energy spectrum have been derived by the electrical signals of TOSS. Our finding not only can provide ocean-wave parameters but also can offer significant and accurate data support for cloud computing of ocean big data.

In situ harvesting undersea energy is a vital method for undersea detector to realize its long‐term and real‐time undersea research. Herein, inspired by the fins with excellent hydrodynamic characteristic and the triboelectric nanogenerator (TENG) with the merits of light‐weight and high‐efficiency at low frequency, an energy harvesting device is designed to harvest undersea energy by bionic‐fin‐structure assisted with multilayer‐structured triboelectric nanogenerator (BFM‐TENG). The good design of geometry and structure enable BFM‐TENG to harvest energy efficiently by the driving of water‐flow from multidirections. Besides, based on the multiarea contact structure and ultrathin dielectric material, the BFM‐TENG could achieve a peak power density of 444 W m −3 under ideal test condition, which is about 1–2 orders of magnitude higher than that of previous work for harvesting wave energy. The findings not only provide a new in situ undersea energy harvesting method for undersea detectors to realize the real‐time, long‐term, and self‐powered undersea research, but also provide a potential strategy to achieve large‐scale undersea energy harvesting.

Although high charge densities of triboelectric nanogenerators (TENG) were achieved by working in high vacuum or charge pumping techniques in atmosphere, owing to their complex structure and/or stability issues, it still remains a great challenge and necessity to directly obtain the high charge density directly through triboelectrification effect in atmosphere. Here, a basic theory about the limitation factors of surface charge density is comprehensively rebuilt through analytical mathematical derivation of the limitation equation. As a result, high surface charge density can be obtained directly by a new optimization methodology, i.e. using thin dielectric layer, which is demonstrated by the designed contact-separation model TENG and sliding model TENG. In addition, the theoretical models of charge decay and charge accumulation during triboelectrification process were built. This work provides not only a new facile and universal optimization methodology for TENG, but also a new insight in the triboelectrification process, both of which will prompt the applications of TENG ranging from powering electronic devices to harvesting large-scale blue energy. (C) 2019 Elsevier Ltd. All rights reserved.

Recently, the direct-current (DC) TENG based on triboelectrification and discharge has been reported, which can not only generate a DC power, but also provide a higher charge density compared to traditional TENG. Here, we report a novel coplanar-electrode DC TENG (CDC-TENG) design which can be easily fabricated by two electrodes, and then a theoretical model is built to illustrate its principle and optimize its output performance. Both theoretical and experimental studies show that the designed device can enhance the energy output, and then the output power is optimized. Furthermore, we develop a three-electrode CDC-TENG to output DC during the reciprocating motion. We apply this CDC-TENG design for rotational energy harvesting and produce a stable constant DC output. This represents an important progress to effectively store the energy harvested by the CDC-TENG with the aim to drive portable/wearable/implantable electronics with the stable output.

Motion vector sensors play an important role in artificial intelligence and internet of things. Here, a triboelectric vector sensor (TVS) based on a direct‐current triboelectric nanogenerator is reported, for self‐powered measuring various motion parameters, including displacement, velocity, acceleration, angular, and angular velocity. Based on the working mechanism of the contact‐electrification effect and electrostatic breakdown, a continuous DC signal can be collected to directly monitor moving objects free from environmental electromagnetic signal interference existing in conventional self‐powered TVSs with an alternative‐current signal output, which not only enhances the sensitivity of sensors, but also provides a simple solution to miniaturize the sensors. Its sensitivity is demonstrated to be equivalent to state‐of‐the‐art photoelectric technology by a comparative experiment in an intelligent mouse. Notably, an intelligent pen based on the miniaturized TVS is designed to realize motion trajectory tracing, mapping, and writing on the curved surface. This work provides a new paradigm shift to design motion vector sensors and self‐powered sensors in artificial intelligent and internet of things.

Electrostatic breakdown is a common but generally negative physical phenomenon. Here, efficient conversion of mechanical energy to electric power is achieved by enhanced direct-current triboelectric nanogenerator (DC-TENG) based on contact electrification and electrostatic breakdown. By verifying the high temperature can not only improve the triboelectric charge density but also enhance electrostatic breakdown of air dielectric due to thermionic emission of electrons and avalanche breakdown effect. Meanwhile an appropriate low atmosphere pressure is another favorable factor to air breakdown in DC-TENG. As a result, its output power density is improved by three orders of magnitude at 473 K and 300 Pa compared to that at 298 K and standard atmosphere pressure. These findings not only provide a new paradigm to design high-performance TENG, but realize efficiently harvesting mechanical energy and thermal energy in one device by coupling the two kinds of physical effects.

The high-output triboelectric nanogenerator (TENG) is indispensable for its practical applications toward industrial products. However, the electricity loss in simple parallel connection among all units and the typically high crest factor output seriously hamper the practical applications of TENG. Here, a rectified TENG is reported in parallel structure to solve the problem of electricity loss in simple parallel connection. The rotational contact-separation structure with phase difference between rectified TENGs addresses high crest factor output and extends service life of rotational TENG simultaneously. The current crest factor is dramatically decreased to 1.31 in multiple rectifier multiple TENG in parallel (MRM-TENG), while that of TENG in simple parallel is higher than 6. Meanwhile, the current output can retain up to approximate to 93% of its initial performance after 7 200 000 rotations under 2.00 r s(-1) of 1000 h. Furthermore, the equivalent current can be in linear growth with low crest factor by making MRM-TENG in parallel for distributed energy supply without electricity loss. This work may provide a new strategy for TENG in parallel to achieve a low crest factor output and long-term cycling stability power generation in distributed energy harvesting for large-scale power application.

Triboelectric nanogenerator (TENG) is a new emerging and cost-effective technology for harvesting water wave energy because of its unmatchable performance in low frequency and randomly directed motions. Here, we report an approach that significantly increased the output power of spherical TENGs by optimizing both materials and structural design. Fabricated with an acrylic hollow sphere as its shell and a rolling flexible liquid/silicone as the soft core, the soft-contact spherical triboelectric nanogenerator (SS-TENG) presents up to 10-fold enhancement to the maximum output charge compared to that of a conventional Polytetrafluoroethylene (PTFE) based hard-contact one, which is resulted from the significantly increased contact area. Besides, the output is tunable through controlling the softness of the liquid/silicone core. Our finding provides a new optimization methodology for TENGs and enable its more promising usage in harvesting large-scale blue energy from water wave in oceans as well as feeble but ubiquitous wind energy.