Hydrothermal Oxidation Research Articles

Copper(II) Oxide Spindle-like Nanomotors Decorated with Calcium Peroxide Nanoshell as a New Nanozyme with Photothermal and Chemodynamic Functions Providing ROS Self-Amplification, Glutathione Depletion, and Cu(I)/Cu(II) Recycling.

Uniform, mesoporous copper(II) oxide nanospindles (CuO NSs) were synthesized via a method based on templated hydrothermal oxidation of copper in the presence of monodisperse poly(glycerol dimethacrylate-co-methacrylic acid) nanoparticles (poly(GDMA-co-MAA) NPs). Subsequent decoration of CuO NSs with a CaO2 nanoshell (CuO@CaO2 NSs) yielded a nanozyme capable of Cu(I)/Cu(II) redox cycling. Activation of the Cu(I)/Cu(II) cycle by exogenously generated H2O2 from the CaO2 nanoshell significantly enhanced glutathione (GSH) depletion. CuO@CaO2 NSs exhibited a 2-fold higher GSH depletion rate compared to pristine CuO NSs. The generation of oxygen due to the catalase (CAT)-like decomposition of H2O2 by CuO@CaO2 NSs resulted in a self-propelled diffusion behavior, characteristic of a H2O2 fueled nanomotor. These nanostructures exhibited both peroxidase (POD)-like and CAT-like activities and were capable of self-production of H2O2 in aqueous media via a chemical reaction between the CaO2 nanoshell and water. Usage of the self-supplied H2O2 by the POD-like activity of CuO@CaO2 NSs amplified the generation of toxic hydroxyl (•OH) radicals, enhancing the chemodynamic effect within the tumor microenvironment (TME). The CAT-like activity provided a source of self-supplied O2 via decomposition of H2O2 to alleviate hypoxic conditions in the TME. Under near-infrared laser irradiation, CuO@CaO2 NSs exhibited photothermal conversion properties, with a temperature elevation of 25 °C. The combined GSH depletion and H2O2 generation led to a more effective production of •OH radicals in the cell culture medium. The chemodynamic function was further enhanced by an elevated temperature. To assess the therapeutic potential, CuO@CaO2 NSs loaded with the photosensitizer, chlorine e6 (Ce6), were evaluated against T98G glioblastoma cells. The synergistic combination of photodynamic, photohermal, and chemodynamic modalities using CuO@CaO2@Ce6 NSs resulted in cell death higher than 90% under in vitro conditions.

Recent Advances in Hydrothermal Oxidation Technology for Sludge Treatment

With the rapid development of urbanization and the widespread adoption of wastewater treatment facilities, the volume of sludge produced has steadily increased. Hydrothermal oxidation (HTO) technology offers an effective solution for sludge reduction, harmless disposal, and resource recovery, making it a highly promising method for sludge treatment. In recent years, HTO has attracted significant attention due to its efficiency and environmental benefits. This paper provides a detailed explanation of the fundamental principles of HTO in sludge treatment, with a focus on the removal of organic pollutants, nitrogen transformation, and phosphorus recovery. The influence of key operational parameters, such as reaction temperature, time, initial oxygen pressure, and pH, on the performance of HTO treatment is also explored. In addition, the research status of HTO sludge treatment and an example of product recovery after treatment are also discussed. It examines the challenges associated with scaling up HTO for large-scale sludge treatment, along with potential research directions for future work. Special attention is given to the innovation of catalysts, with the goal of achieving self-catalysis in sludge treatment. Moreover, considering that ammonia nitrogen (NH3-N) is a major intermediate product in HTO, its removal, as well as the prediction and planning of other unintended products, remains a key issue. Further areas of interest include improving sludge dewatering performance and enhancing the production of valuable single carboxylic acids, which can boost resource recovery efficiency. This paper also highlights the diversification of sludge applications after HTO treatment. By providing insights into future development trends, this review offers valuable references for further research and practical applications. The ultimate goal is to support the development of HTO as a sustainable and efficient solution for sludge treatment, addressing environmental concerns while maximizing resource recovery opportunities.

Advancement of Ionic Complexes Based on Multivalent Carbon Dot Polyanions for Applications in Electrochemical Systems

Carbon dots, also known as carbon quantum dots or graphene quantum dots (C-dots), have garnered significant attention due to their promising applications in various fields such as energy, catalysis, bioimaging, and nanomedicine. Typically, C-dots exhibit zero-dimensional characteristics with hybridized carbon structures at the core and functional groups like hydroxyl and carboxyl at the edges.In this talk, I will highlight our recent advancements in utilizing ionic complexes based on C-dots for electrochemical applications, serving as supporting electrolytes and anionic dopants. We've developed nano-sized multivalent C-dot polyanions through a hydrothermal oxidation process of carbon nanofibers, forming complexes with alkali cations such as Li+, Na+, and K+. Consequently, we investigated the potential applications of ionic complexes based on C-dot as electrolytes for lithium-ion batteries and electrochromic devices. The ionic complexes demonstrate low Coulombic energy, exceptional thermal/electrochemical stability, and good ionic conductivity when dissolved in both aqueous and organic solvents. Molecular dynamics simulation with the electrochemical characterization reveals that the ionic complexes provide highly abundant free metal cations with highly stable C-dot polyanions and negligible ion pairs in solution. Furthermore, we have successfully implemented a novel approach to fabricate nanoarchitectures based on C-dots as an electrode-active material with outstanding electrochemical catalytic activity which is suitable for electrochemical biosensors and H2O2 reduction. Figure 1

Evaluating sustainable energy pathways: Economic perspective on advanced hydrogen production

This investigation seeks to evaluate hydrogen generation technologies in China with a focus on two commercial processes, namely hydrothermal oxidation and supercritical water gasification of organic waste from 2011 to 2021. This period witnessing major development, and highlight the key determinants of hydrogen production. The present study was mainly concerned with the enhancement of SCWG processes for hydrogen generation from microalgae and other potential feedstock. Some of the significant observations made in this period are the critical role of biomass composition, choice of catalyst, and operating conditions in increasing H-producing capabilities of reactor systems. The authors of research affirm that the feedstock with a high carbohydrate content and low levels of protein are the most suitable for hydrogen generation. Thus, expanding research on Supercritical Water Gasification, there is the development of HTO methods to consider various pathways of hydrogen production and their connection with existing energy networks. It also studied the effects that several types of catalysts embracing the heterogeneous transition metals and the homogeneous alkali metal compounds have on the efficiency of hydrogen production. These changes have rendered the hydrogen generation process to make more precise predictions and/or course corrections on the process. The studies that have been done between 2011 and 2021 show significant improvements in the ways that sustainable and efficient hydrogen generation technology can be created in China. The results provide a solid platform for future improvements and stress positive impacts that can be provided by these technologies for China's sustainability and energy transition progress.

Variations in the optical and thermoelectric behavior of ZnCo2O4 nanostructures as a function of synthesis temperature

Zinc cobalt oxide nanostructures were synthesized by electrochemical deposition of zinccobalt alloy at various bath temperatures (15, 30, 45 and 60 ˚C) and its hydrothermal oxidation at 100 ˚C. X-ray diffraction pattern and Raman spectroscopy data reveals the formation of spinal structure of ZnCo2O4. Photoluminescence spectra of the samples exhibit broad peaks with a red shift in the emission energy. Diffused reflectance spectroscopy measured the band gap of the synthesized materials; band gap is 3.06, 3.03, 3.02 and 2.99 eV, for samples electrodeposited at 15, 30, 45 and 60 ˚C, respectively. Optical conductivity of synthesized materials decreases with increasing deposition layers while reflectance shows opposite trend. Thermoelectric set up measures the change in potential difference through synthesized materials when different temperatures are applied and an increment in potential were observed. Seebeck co-efficient and power factor are also studied as function of bath temperature.

Neogene Hydrothermal Fe‐ and Mn‐Oxide Mineralization of Paleozoic Continental Rocks, Amerasia Basin, Arctic Ocean

AbstractRocks dredged from water depths of 1,605, 2,500, 3,300, and 3,400 m in the Arctic Ocean included Paleozoic continental rocks pervasively mineralized during the Neogene by hydrothermal Fe and Mn oxides. Samples were recovered in three dredge hauls from the Chukchi Borderland and one from Mendeleev Ridge north of Alaska and eastern Siberia, respectively. Many of the rocks were so pervasively altered that the protolith could not be identified, while others had volcanic, plutonic, and metamorphic protoliths. The mineralized rocks were cemented and partly to wholly replaced by the hydrothermal oxides. The Amerasia Basin, where the Chukchi Borderland and Mendeleev Ridge occur, supports a series of faults and fractures that serve as major zones of crustal weakness. We propose that the stratabound hydrothermal deposits formed through the flux of hydrothermal fluids along Paleozoic and Mesozoic faults related to block faulting along a rifted margin during minor episodes of Neogene tectonism and were later exposed at the seafloor through slumping or other gravity processes. Tectonically driven hydrothermal circulation most likely facilitated the pervasive mineralization along fault surfaces via frictional heating, hydrofracturing brecciation, and low‐ to moderate temperature Fe‐ and Mn‐rich hydrothermal fluids, which mineralized the crushed, altered, and brecciated rocks.

Hierarchical porous MXene film with diffusion path optimization for supercapacitor

MXenes have immense potential in electrochemical energy storage owing to their outstanding physicochemical properties such as their oxygen-containing groups that impart additional pseudocapacitance to acidic electrolytes. However, during electrode assembly, MXene nanosheets undergo restacking because of hydrogen bonding and van der Waals forces, which causes electrolyte ions to traverse long diffusion pathways between the long and narrow nanosheets. Exploiting the oxidative properties of Ti3C2Tx, a hierarchical porous MXene film with micro-, meso- and macroporous structures was successfully prepared using a simple hydrothermal oxidation and etching process to create micro- and mesoporous structures, followed by ice templating to prepare three-dimensional (3D) linked macroporous structures. Because these hierarchical pores have synergistic effects on electrochemical activity and electrolyte ion diffusion, the film attained a specific capacitance of 539F/g at a current density of 2 A/g when it was used as a supercapacitor electrode, which corresponds to one of the highest values reported for MXene-based electrodes. The film retained 83% of its specific capacitance when the current density was increased to 40 A/g, and exhibited excellent cycling stability. By using this multi-porous MXene design, synergistic improvement in ion diffusion was successfully realized and thus a new strategy to prepare high-performance supercapacitor electrode materials was developed.

Anglian Water to Develop Resources from Waste

Collaboration to convert biosolids with hydrothermal oxidation

Exploiting the potential of images from the aster and landsat 9 satellites for the mapping of hydrothermal alteration minerals associated with mineralization in the departments of Abtouyour and Guera, located in the Chadian massif central (republic of Cha

This article deals with the use of remote sensing with Aster and Landsat 9 imagery for mapping hydrothermal alteration minerals and oxides in relation to mineralization. Aster VNIR (Visible and Near Infrared) and SWIR (Mean Infrared) data are used to calculate PCA (Principal Component Analysis), RBD (Relative Band Depth) and BR (Band Ratio). These different parameters are used to highlight the groups of hydrothermal alteration minerals and oxides. Landsat data are used for mapping lithological units using PCA and BR. The identified mining areas coincide with the gold planning sites of Toumka and Lellé and allow to know the interesting areas for future mining prospecting campaigns in the departments of Abtouyour and Guéra (Guéra province).

Chemiresistive flexible gas sensor for NO2 sensing at room-temperature using in situ constructed Au@In2S3/In2O3 hybrid microflowers

The construction of a novel Au nanoparticles loaded In2S3/In2O3 hybrid microflowers composite was conducted through a well-designed hydrothermal and partial oxidation method and used for NO2 sensing at room-temperature (RT). The characterization data confirmed the hybrid structures and demonstrated that the ratio of adsorbed oxygen species on the surface increased after partial oxidation. The sensing performance of flexible gas sensors based on In2S3/In2O3, In2O3, AuxIn2S3/In2O3 (x = 0.5, 1 and 2 wt%) were tested and compared at RT. Heterostructure construction and Au NPs loading significantly improved the sensing properties at RT. Peculiarly, the response value of 1 wt% Au NPs loaded In2S3/In2O3 (Au1In2S3/In2O3) sensor for 100 ppm NO2 at RT was 20.7, which was 9.2 times higher than that of In2O3 sensor. Meanwhile, it also possessed excellent selectivity, fast response/recovery time (12/27 s), good repeatability, long-term and mechanical stability. The outstanding sensing performance for NO2 at RT mainly associated to the heterojunction between In2S3 and In2O3 and the catalytic effect of Au NPs. Finally, density functional theory (DFT) was used to calculate and analyze the gas adsorption and charger transfer, which related to the enhanced sensing performance.

Preparation of Stainless Steel Superhydrophobic Surface and Analysis of Hydrophobic Mechanism.

By analyzing the application conditions of hydrothermal oxidation equipment, we found that the corrosion resistance of stainless steel is crucial. It is necessary to prepare superhydrophobic surface to improve the corrosion resistance and find a cost-effective and environmentally friendly preparation method. Therefore, this paper proposes a method combining nanosecond laser and post-treatment, which uses nanosecond laser to etch microstructure and reduces the surface energy through diverse post-treatment methods to achieve hydrophobicity. The surface morphology characteristics were studied, the wettability of various post-treatment methods was compared, and the hydrophobic mechanism was analyzed. The results show that the groove width has a significant impact on the surface morphology. Superhydrophobic surface can be obtained immediately after heat treatment and fluorosilane modification, while natural storage requires more than one month. All of the post-treatment can obtain hydrophobicity by reducing the surface energy, but the chemical composition is distinct. The cost-effective composite process of laser and heat treatment plays a guiding role in future research on the preparation of stainless steel superhydrophobic surface and has broad prospects in the future in large-scale production and application.

Recovering Valuable Chemicals from Polypropylene Waste via a Mild Catalyst-Free Hydrothermal Process.

Waste polypropylene (PP) presents a significant environmental challenge, owing to its refractory nature and inert C-C backbone. In this study, we introduce a practical chemical recovery strategy from PP waste using a mild catalyst-free hydrothermal treatment (HT). The treatment converts 64.1% of the processed PP into dissolved organic products within 2 h in an air atmosphere at 160 °C. Higher temperatures increase the PP conversion efficiency. Distinct electron absorption and emission characteristics of the products are identified by spectral analysis. Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) reveals the oxidative cracking of PP into shorter-chain homologues (10-50 carbon atoms) containing carboxylic and carbonyl groups. Density functional theory (DFT) calculations support a reaction pathway involving thermal C-H oxidation at the tertiary carbon sites in the polymer chain. The addition of 1% H2O2 further enhances the oxidation reaction to produce valuable short-chain acetic acids, enabling gram-scale recycling of both pure PP and disposable surgical masks from the real world. Techno-economic analysis (TEA) and environmental life cycle costing (E-LCC) analysis suggest that this hydrothermal oxidation recovery technology is financially viable, which shows significant potential in tackling the ongoing plastic pollution crisis and advancing plastic treatment methodologies toward a circular economy paradigm.

Formation of hydrothermal ferromanganese oxides in the Daini-Nishi-Yamato Seamount, Sea of Japan: Do they really contain critical-metal particles?

In submarine environments, ferromanganese (Fe–Mn) oxides are formed via various processes. Although hydrothermal Fe–Mn oxides are generally valueless as mineral resources because of their low critical metal content, they reflect temporal changes in hydrothermal activity. Metal particles, including native metals, have been observed in hydrothermal Fe–Mn oxides and associated igneous rocks that are extensively distributed in the Sea of Japan. This finding can have significant implications for metal transport in submarine hydrothermal systems. However, the existence of these metal particles requires verification because their thermodynamic coexistence with Mn oxides is challenging and has only been reported by one research team. Here, we show the growth structure and geochemistry of hydrothermal Fe–Mn oxides and volcanic rocks from the Daini-Nishi-Yamato Seamount in the Sea of Japan. The chemical and Nd–Sr isotopic compositions of the volcanic rock indicated that the Daini-Nishi-Yamato Seamount formed through magmatism after back-arc spreading in the Yamato Basin at 10–17 Ma. The hydrothermal Fe–Mn oxides consisted of Ti-rich layers that formed earlier and Ti-poor layers that formed later. The Ti-rich layers precipitated from Ti-rich hydrothermal fluids because of water–rock interactions at higher temperatures during the early stages of hydrothermal activity. During the late stages of hydrothermal activity, Ti-poor layers formed, likely because of a decrease in the temperature of the water–rock interactions and/or the depletion of Ti in the host rocks. However, unlike in previous studies, metal particles such as Ag and rare earth elements were not detected in our samples, which were impregnated with resin to prevent contamination during the polishing process. These results strongly suggest that the metal particles reported in the previous studies were contaminants.

O2-H2O2 high-efficient co-oxidation of carbohydrate biomass to formic acid via Co3O4/C nanocatalyst

The conversion of biomass to chemicals/fuels has emerged as a valuable solution that offers both environmental and economic benefits, with the transformation of carbohydrate into formic acid garnering escalating scholar interest. However, the relative limited efficiency of catalyzed-oxidation or expensive cost of H2O2 and alkali in wet hydrothermal oxidation impose limitations on industrialization. This paper proposed a new idea for formic acid production by O2-H2O2 co-oxidation of carbohydrate. A two-step reaction method was developed, where the initial step is engineered to regulate the carbon chain cleavage of carbohydrates to augment the production of active intermediate. Oxygen was employed in the subsequent step as effective oxidant through free radical mechanism, resulting in a formic acid yield of 82.6%. Theoretical calculation, intermediates detection and real time EPR confirmed the reaction mechanism. Finally, the universality of the reaction was verified by using disaccharides and polysaccharides such as cellulose as substrates.

High-efficiency phosphorus recovery from hypophosphite and phosphite-containing wastewater via a new electrodialysis enrichment and hydrothermal oxidation coupling process

Hypophosphite is an ideal reducing agent used in industries such as electroplating. However, the presence of high concentrations of hypophosphite and phosphite in industrial wastewater necessitates the consumption of large amounts of strong oxidants to oxidize hypophosphite to phosphate for subsequent removal by precipitation. This study introduces an innovative application of green hydrothermal process for the oxidation treatment of inorganic materials, combined with the ion enrichment advantages of electrodialysis. This novel coupling process achieves efficient enrichment and rapid oxidation of high-concentration hypophosphite and phosphite with minimal chemical consumption and more economical operating costs, yielding high-quality phosphate resources. Under electrodialysis conditions with a particle electrode dosage of 3 %, a voltage of 20 V, and a residence time of 10 h, the total phosphorus in the middle chamber was reduced from 2801.17 mg/L to 119.05 mg/L, achieving an anodic enrichment rate of 95.75 %. Under hydrothermal conditions of 400 °C for 15 min, with an H2O2 doping ratio of 7 % and a Ca(OH)2 doping ratio of 35 g/L, the peak oxidation rates of H2PO2− and HPO32− reached 99.38 %, and 99.39 % of phosphorus was transferred from the liquid phase to the solid phase in recyclable forms such as Ca5(PO4)3OH, Ca3(PO4)2, and FePO4. H2O2 enhances the hydrothermal oxidation process by increasing the concentration of free radicals. Ca(OH)2 acted as a catalyst to enhance •OH generation during the hydrothermal reaction, provided Ca2+ required for phosphorus recycling, and increased the pH to obtain crystalline products with a high Ca/P molar ratio. Compared to conventional advanced oxidation processes, the electrodialysis and hydrothermal coupling process offers a clean alternative for treating high-concentration hypophosphite and phosphite in plating wastewaters, achieving a cost saving of 22.99 %.

Hydrothermal oxidation improves the corrosion resistance of titanium and initial cellular responses

Hydrothermal oxidation is the key reaction in the hydrothermal treatment for titanium-based biomedical materials. However, there is still a lack of detailed characterization and in-depth research on the bonding between the oxide film and the substrate, the protection for substrate and the early cellular responses. In this study, nanostructured oxide films were prepared on the titanium surface through hydrothermal oxidation in pure water. The interfacial structure was thoroughly analyzed, corrosion resistance was evaluated, and wetting properties, surface energy and protein adsorption capacity were measured; the interaction between cells and the oxide film was revealed through fluorescence staining and microscopic observations. The results showed that nanocrystalline anatase grew in situ on the titanium surface between 150–200 °C, forming a dense oxide film of approximately 40–50 nm. The oxide film significantly improved the corrosion resistance of the substrate, providing strong shielding protection even after immersion in a solution containing fluoride ions for 30 days. Furthermore, the oxide film endowed the titanium substrate with superhydrophilicity and high surface energy, enhancing protein adsorption, accelerating the polymerization of actin and the formation of stress fibers, and facilitating a tight bond between the cell matrix and the substrate surface; cell attachment and spreading were greatly improved.

An efficient Urea-formaldehyde resin degradation method by hydrogen peroxide and malic acid: At three-mole ratios

Urea-formaldehyde (UF) resin has a high annual output, but the used and waste UF resin poses a challenge for recycling due to the difficulty in effectively decomposition them. In this study, A novel one-step degradation method was proposed, i.e., using eco-friendly malic acid and hydrogen peroxide to degrade cured UF resin residues using carboxylic acid through the hydrothermal oxidation method (HPMA), which was proved to have high cured UF resin degradation efficiency. This method will offer a new path for effectively recycling the UF resin out of service.

Magmatic sulfide oxidation drives crustal PGE mobilization: Implications for hydrothermal PGE mineralization

Platinum-group elements (PGEs) have a strong affinity for sulfur and tend to accumulate in the deep continental crust, either concentrated within magmatic Cu-Ni-PGE deposits or dispersed throughout disseminated sulfides. However, PGE enrichment in shallow magmatic-hydrothermal systems implies an obscure link to deep sulfide destabilization, which releases PGEs into ore-forming fluids. To bridge this gap, our study investigates the PGE composition of magmatic sulfides with oxidative textures in dacitic rocks from the southwestern Okinawa Trough. We identified three groups of magmatic sulfides, primarily precipitated as Cu-poor monosulfide solid solution (MSS), which formed at distinct stages of magma evolution from deep to shallow crustal levels. Group A sulfides manifest as small-sized inclusions (<30 μm) within most high-Mg olivines, whereas Group B and C sulfides are larger (50–500 μm) and occur within cognate xenoliths of mafic cumulate rocks and the groundmass of host dacites. Group B and C sulfides exhibit distinct oxidative textures and newly-formed mineral assemblages, including magnetite, hematite, goethite, and magnetite ± pyrite, alongside hydrothermal silicate minerals, respectively. We attribute the oxidation process to the infiltration of orthomagmatic fluids exsolved from mafic magma that had underplated the sulfide-bearing felsic magma reservoir, which was nearly solidified. By comparing the chemical compositions between pristine sulfides and their oxidative remnants, we observed extensive mobilization of Pd, Pt, Cu, Ag, Ni, and Co from the altered sulfides of Group B, while Au enrichment occurred as nanoparticles under high oxidation states. In contrast, Au was extracted along with other mobile metals from the altered sulfides of Group C, with Pt remaining in place under more reduced conditions. These distinct scenarios may lead to the formation of PGE-rich and Au-rich fluids, respectively. The formation of deep crustal MSS and subsequent hydrothermal oxidation under varying redox conditions thus provides a viable mechanism for trans-crustal PGE mobilization and inter-element fractionation, typical of PGE-rich magmatic-hydrothermal deposits.

Application of red mud in hydrothermal remediation of Cd- and petroleum-contaminated soil

Developing a technique to simultaneously remove the harmful effects of organic matter and heavy metals from composite-polluted soil is of great importance, as it could reduce the time required for land restoration. In this study, red mud was used as an additive to remediate Cd- and petroleum-contaminated soil (CPCS) using hydrothermal technology, and its effects on the total organic carbon (TOC), total Cd, and available Cd (CdA) in the soil were evaluated. During hydrothermal extractions, when the temperature increased from 150 °C to 350 °C, the TOC removal efficiency increased from 16.32 % to 61.29 %, while the ratio of CdA (RCdA) decreased from 32.28 % to 10.72 %, and after adding 2 g of red mud, the RCdA decreased from 46.54 % to 20.30 %. During hydrothermal oxidations, adding red mud increased the TOC removal efficiency from 78.44 % at 0 g to 84.62 % at 3 g when the amount of oxidant was 30 mL, and RCdA decreased from 31.62 % to 19.46 %. These results indicate that hydrothermal treatments could significantly affect the organic substances in soil, and red mud played the roles of a catalyst and passivator during hydrothermal oxidation. The passivation of Cd by red mud was promoted under high-temperature conditions and an appropriate increase in the oxidant concentration and reaction time could promote the removal of organic matter and the reduction of CdA. However, excessive oxidants and reaction time could cause further decomposition of organic matter, leading to a decreased ability to capture Cd.

Insulation coating via hydrothermal oxidation for high-frequency FeSiAl soft magnetic composites

Soft magnetic composites (SMCs) play a crucial role in electronic devices owing to their high saturation magnetization. However, conventional insulation methods employed in SMCs exhibit inadequate insulation reliability, thereby restricting their further application in high frequencies. In this study, hydrothermal oxidation is introduced for insulation coating in the preparation of FeSiAl SMCs. When treated at 150 ℃ for 2 h, an insulation layer comprising of Al2O3, SiO2, Fe3O4 and Fe2O3 is formed on the surface of FeSiAl. The most optimal sample is achieved with saturation magnetization of 134.3 emu/g, presenting no significant reduction in saturation magnetization compared to the untreated sample. Cut-off frequency exceeding 300 MHz, and power loss of 503.7 kW/m3 (@7 MHz, 5 mT) are also obtained. This study suggests that hydrothermal oxidation could be a dependable method for fabricating high-frequency SMCs.