JOM最新文献

This review aims to clarify the evolution of nanogenerator technology, specifically piezoelectric and triboelectric systems, to exploit the human body's mechanical energy as a realistic power source for wearable Internet of Things (IoT) devices. Bibliometric analysis was used to search and analyze related documents from Scopus from 2007 to August 30, 2024. From the Scopus database, 1575 articles were selected and visualized to describe the most cited journals, frequently used keywords, and productive countries in developing and collaborating on the research topic. Additionally, Nano Energy is the most cited journal; China is the most productive and active country in building collaborations; and Wang et al. is the most cited author, with their first zinc oxide nanogenerator design garnering 709 citations. The review also discusses the materials frequently used in nanogenerators, and it has been found that the hand is the most commonly chosen part because it moves the most during daily activities. However, the greatest voltage is harvested when the nanogenerator is placed on the foot. The analysis results can help researchers understand the development of nanogenerators and inspire them to make nanogenerators from more efficient, self-powered, stable, and durable materials.

Through Nb microalloying, the grain size of medium-carbon manganese steel used for 35MnB track links was refined. The growth behavior of austenite grains was investigated under different heating temperatures and holding times. The morphology and evolution patterns of the precipitates were analyzed. Results indicated that as temperature increased, precipitate dissolution was the primary driver of grain size growth. At a holding time of 3600 s, abnormal grain coarsening in 0Nb steel commenced at 950°C, while this phenomenon was delayed to 1000°C for 0.011%Nb and 0.019%Nb steels. At 900°C holding for 7200 s, the average grain size of 0Nb steel was 21.46 µm, while 0.011%Nb and 0.019%Nb steels were 19.35 µm and 18.2 µm. The size of spherical Nb-rich precipitates was significantly smaller than that of rectangular Ti-rich precipitates. As the temperature increased, the volume fraction of NbC gradually decreased. The complete dissolution temperatures of NbC in 0.011%Nb and 0.019%Nb steels were 1124°C and 1199°C, respectively. Different models were established to describe the relationship between the steel grain size and temperature and holding time, and the Sellars model provided good consistency between predicted and measured results, offering a reference for the austenite grain growth behavior in 35MnB steel.

This study analyzes the pipe bursting accident of S30432 austenitic stainless-steel final stage superheater in a thermal power plant, and reveals the failure mechanism through macroscopic morphology examination, mechanical property testing, metallographic organization analysis, and precipitation phase EDS analysis. The results show that the failure was the result of the synergistic effect of flue gas corrosion thinning (external cause) and metallurgical organization aging (internal cause), and because the high sodium sulfur flue gas from the Zhundong coal induced molten salt corrosion, which led to the local thinning of the pipe wall. At the same time, overheating service prompted the coarsening of a grain boundary precipitation phase, the precipitation of a large number of M₂₃C₆, σ phase, and NbC phase, so that the grain boundary strength decreased, and the material-bearing capacity decreased. At the same time, the temperature of the tube service was calculated, and the fact that the tube safety margin was reduced and the risk of pipe burst was high was verified by calculating the circumferential stress. This study provides a theoretical basis for the selection of heat-resistant steel for ultra-supercritical thermal power units and the safe blending of Zhundong coal.

This study investigated the effect of powder mixture-driven aluminum activity on the microstructure of out-of-pack aluminide coatings applied to selective laser melting-fabricated Inconel 939 substrate. The samples were aluminized via a single-step process at 1100°C for 2.5 h using a 10 wt.% Al (99.99)-5 wt.% NH₄Cl -balance Al₂O₃ high-activity pack. The combination of process temperature and aluminum concentration reflects high-temperature high-activity (HTHA) conditions, though its mechanism remains debated due to inconsistent findings in the literature. Formation mechanisms were analyzed using SEM, EDS, XRD, and microhardness (Vickers) test. These findings were also compared with reference aluminide coatings produced via high-temperature low-activity (HTLA). Utilizing HTHA conditions resulted in inward-grown coatings with a thick additive layer (470 ± 9 μm), including precipitates and intermetallics, and a thin internal diffusion zone (IDZ) (22 ± 3 μm). XRD and SEM-EDS analysis suggested that δNi₂Al₂ and β-NiAl phases were present in the additive layer. The average hardness level of the additive layer was 954 ± 96 HV; however, the hardness varied within additive layer due to possible phase transformations (from δ-Ni₂Al₃ to β-NiAl). Although HTHA coatings exhibit both beneficial and potentially undesirable characteristics, further high-temperature corrosion testing is required to assess their overall suitability for turbines.

Copper, a common impurity in petroleum, poses a significant risk of corrosion to iron and aluminum transport pipelines, adversely affecting agricultural machinery and critical infrastructure used in resource transportation. This study presents a novel nano-sensor network platform specifically designed to detect and facilitate the mitigation of copper contamination in petroleum systems. The proposed network integrates specialized nano-sensors that identify copper ions in real time and signal embedded catalytic or reactive subsystems responsible for transforming copper impurities into less harmful or potentially useful forms—such as gases, metal compounds, hydrocarbons, or organics—depending on operational scenarios. While the sensors do not perform chemical conversion themselves, they serve as intelligent triggers within a coordinated mitigation system. This approach combines precision detection with adaptive response mechanisms, offering a technological advancement over conventional filtration or chemical treatment methods. By minimizing copper’s corrosive effects, the research aligns with broader nanotechnology goals in agriculture and energy, promoting sustainability through improved resource efficiency, environmental protection, and extended infrastructure lifespan. Platform performance is evaluated through simulation scenarios demonstrating its scalability, responsiveness, and potential for integration within existing petroleum infrastructure. These findings highlight the potential of the system to support sustainable energy transitions, reinforce transport resilience, and enhance the safety and durability of petroleum distribution networks.

Additive friction stir deposition (AFSD) is a solid-state additive manufacturing technique capable of repairing aluminum alloys with identical filler material, but there are few studies about the lubricant-free round feedstock variant or post-processing avenues for improving performance. The current study investigates the impact of hybrid frictional diffusional bonding (HFDB) as a post-processing route to improve the performance of aluminum alloy AA7075 repaired via AFSD. Implementation of a novel actuator force-control scheme enabled AFSD repairs to be conducted without the aid of lubrication as a potential contaminant. Repairs receiving a combination of HFDB and a post-deposition heat treatment (PDHT) exhibited > 90% of the yield strength and ultimate tensile strength of the wrought control, representing a marked increase relative to repairs that underwent PDHT without HFDB. Fatigue testing of repairs that underwent HFDB and PDHT revealed comparable cyclic performance to the wrought control in the high-cycle regime, indicating the potential of HFDB as a post-processing route to improve repair performance under static and cyclic loading.

The equiatomic NiTi shape memory alloys (SMAs), known as nitinol, exhibit significant potential as a biomaterial for biomedical applications because of their distinctive properties, including the superelasticity and shape memory effect, which are superior to those of conventional materials. Due to their excellent biocompatibility, NiTi alloys are used in cardiovascular devices, orthopedic implants, surgical tools, and orthodontic devices. Despite these advantages, wear debris and nickel ion release challenges can compromise biocompatibility and provoke adverse cellular reactions, posing health risks. To enhance biocompatibility and prolong the implant lifespan, improvements in NiTi's mechanical (e.g., hardness values reported between 201 HV and 707 HV), tribological (coefficient of friction reduced to 0.31), and electrochemical properties are essential before human implantation. Moreover, NiTi alloys are generally considered non-cytotoxic if cell viability is > 70%. In addition, compared to conventional metallic biomaterials, NiTi alloys have a relatively low elastic modulus, ranging from 20 to 50 GPa in the martensitic phase and 40 to 90 GPa in the austenitic phase, which is much closer to that of natural bone (~30 GPa). This review paper summarizes current research and advancements in NiTi shape memory alloys, emphasizing their electrochemical and tribological properties. It also briefly addresses the biocompatibility issues associated with NiTi alloys and the strategies researchers employ to solve them.

This study investigates the physico-mechanical and flame-retardant properties of functionally graded composites (FGCs) created using material extrusion (MEX)-based 3D printing. Composites were developed by blending polylactic acid (PLA) with carbon fiber-reinforced PLA (PLA-CF) in varying ratios from neat PLA to neat PLA-CF. Key properties analyzed included density, water absorption, shrinkage, tensile strength, and flammability. Density decreased from 1.14105 g/cm³ to 1.05124 g/cm³ with increased CF content, while water absorption rose due to greater porosity. The 90PLA/10PLA-CF blend emerged as optimal, reducing density by 7.8%, minimizing shrinkage by 80.9%, and retaining 99.7% of PLA’s density. Tensile testing revealed the 70PLA/30PLA-CF blend had the highest strength gains, with L_max, UTS, and E increasing by up to 79.77%. Even the 90PLA/10PLA-CF blend showed strength improvements over neat PLA-CF. Flame tests indicated better resistance with higher CF content; neat PLA burned rapidly, whereas PLA-CF blends showed reduced dripping and slower degradation. Mass loss during burning decreased from 17.5% in neat PLA to 6.45% in 30PLA/70PLA-CF. These results highlight the potential of PLA/PLA-CF FGCs for applications demanding improved mechanical performance, dimensional stability, and flame retardancy.