Nano-sized Oxide Particles Research Articles

Mechanical Behavior of Oxide Dispersion Strengthened Steel Directly Consolidated by Rotary Swaging.

Among the main benefits of powder-based materials is the possibility of combining different constituents to achieve enhanced properties of the fabricated bulk material. The presented study characterizes the micro- and sub-structures and related mechanical properties of ferritic steel strengthened with a fine dispersion of nano-sized Y2O3 oxide particles. Unlike the typical method of preparation via rolling, the material presented herein was fabricated by direct consolidation from a mixture of powders using the versatile method of hot rotary swaging. The mechanical properties were evaluated at room temperature and also at 1300 °C to document the suitability of the prepared steel for high-temperature applications. The results showed that the imposed shear strain, i.e., swaging ratio, is a crucial parameter influencing the microstructure and, thus, material behavior. The workpiece subjected to the swaging ratio of 1.4 already exhibited a sufficiently consolidated structure with ultra-fine grains and featured high room-temperature microhardness values (up to 690 HV0.5), as well as a relatively high maximum flow stress (~88 MPa) when deformed at the temperature of 1300 °C with the strain rate of 0.5 s-1. However, the dispersion of oxides within this sample exhibited local inhomogeneities. Increasing the swaging ratio to 2.5 substantially contributed to the homogenization of the distribution of the Y2O3 oxide particles, which resulted in increased homogeneity of mechanical properties (lower deviations from the average values), but their lower absolute values due to the occurrence of nucleating nano-sized recrystallized grains.

Microstructural and Tensile Property Differences between Ni-16Mo and ODS alloys Fabricated by the Powder Metallurgy Processes

Ni-16Mo and ODS alloys were fabricated by the powder metallurgical processes, and their microstructures and tensile properties were investigated. Ni-16Mo-7Cr and Ni-16Mo-7Cr-0.3Ti-0.35Y2O3 (in wt.%) alloys were prepared by mechanical alloying, uniaxial hot pressing, and heat treatment processes. Microstructural observations of these alloys revealed that the Ti and Y2O3 additions to a Ni-16Mo alloy were significantly effective to refine the grain size and form nano-sized Y-Ti-O oxide particles. Consequently, the tensile strengths at room temperature and 700°C were considerably enhanced. This improvement of tensile properties can be mainly attributed to the formation of nano-sized oxide particles, as well as the refined grain size. It is thus concluded that Ni-16Mo alloy with Ti and Y2O3 additions would be very effective in improving the mechanical properties especially at elevated temperatures.

The Application of Micro- and Nano-Sized Zinc Oxide Particles Differently Triggers Seed Germination in Ocimum basilicum L., Lactuca sativa L., and Lepidium sativum L. under Controlled Conditions

The Application of Micro- and Nano-Sized Zinc Oxide Particles Differently Triggers Seed Germination in Ocimum basilicum L., Lactuca sativa L., and Lepidium sativum L. under Controlled Conditions

Enhancing the Mechanical Performance of Concrete Slabs through the Incorporation of Nano-sized Iron Oxide Particles (Fe2O3)

The utilization of recycled iron in durable concrete production has gained attention for enhancing sustainability and resource efficiency. Simultaneously, incorporating nanoparticles as supplementary cementitious materials (SCMs) offers significant benefits. Introducing nano-sized iron particles (Fe2O3) into the cement paste results in a compact microstructure, improving strength, and durability. In this study, we investigate the bending behavior of concrete slabs reinforced with Fe2O3 nanoparticles using the non-local quasi-3D shear deformation theory based on Eringen's non-local differential constitutive relations. To characterize the elastic material properties of the nanocomposite, we employ Eshelby's homogenization model. In order to extend the applicability of our findings, we assume that the concrete plate rests on Kerr's foundation, which includes a shear layer connected to upper and lower springs. By deriving the equations of motion using the principle of virtual work, we establish a comprehensive framework for analyzing the bending of the concrete plate. To solve the equilibrium equations for a simply supported concrete plate, we present Navier's analytical solutions. Our investigation considers various influential parameters, such as the concentration of Fe2O3 nanoparticles in the concrete matrix, the elastic constants of the soil medium, different types of bending loads, and size-dependent nonlocal parameters. One of the most captivating findings of this study is that the incorporation of 30 wt% of iron nanoparticles in concrete leads to a remarkable improvement of 60% in the elastic properties of the material. Additionally, this same amount of iron nanoparticles has shown the potential to reduce the deflection of thin plates by over 60%.

Manufacturing Oxide Dispersion Strengthened (ODS) steel plate via cold spray and friction stir processing

Oxide dispersion strengthened (ODS) steels, traditionally fabricated by ball milling and conventional powder metallurgy techniques to achieve bulk form, followed by intricate rolling and thermal treatment steps to achieve plate or sheet form. Here, we present a novel processing route that combines cold spray (CS) with friction stir processing (FSP) to manufacture ODS steel plate directly from gas atomization reaction synthesis (GARS)-prepared powder, thus no rolling steps involved. Microstructural and mechanical characterizations were performed to assess the quality and properties of the resulting ODS steel plate. Our findings demonstrate that the slightly porous CS deposited layer was fully consolidated after FSP, yielding a fully dense ODS steel plate that exhibited a favorable tradeoff between strength and ductility upon extraction from the substrate. Furthermore, through microstructural analysis, we revealed the presence of an appreciable density (∼1022/m3) of nano-sized oxide particles, with the majority being smaller than 5 nm via the combined CS + FSP fabrication route. This work serves as a first proof-of-concept demonstration of the manufacturing approach described herein, offering a possible alternative route for producing ODS steel plates.

Corrosion of 316L stainless steel produced by laser powder bed fusion and powder metallurgy in pressurized water reactor primary coolant

Corrosion mechanism of 316 L stainless steel produced by laser powder bed fusion-hot isostatic pressing (LPBF-HIP) and powder metallurgy-hot isostatic pressing (PM-HIP) is studied with in-situ electrochemical impedance measurements coupled to detailed oxide film characterization. Quantitative analysis of impedance spectra using the Mixed-Conduction Model and estimation of local kinetic and transport parameters by interpretation of in-depth elemental composition profiles indicated lower corrosion and oxidation rates of LPBF-HIP and PM-HIP materials in comparison to conventional wrought 316 L. This owes to a higher fraction of low-angle grain boundaries, smaller grain size, the presence of nano-sized oxide particles and elevated Cr and Ni contents.

Formulation of high-temperature strength equation of 9Cr-ODS tempered martensitic steels using the Larson–Miller parameter and life-fraction rule for rupture life assessment in steady-state, transient, and accident conditions of fast reactor fuel

This paper discusses the applicability of Straalsund et al.’s technique for combining the Larson–Miller parameter (LMP) and life-fraction rule to form a single high-temperature strength equation for 9Cr-oxide-dispersion-strengthened (ODS) tempered martensitic steels (TMS). It uses the extensive dataset on creep rupture, tensile, and temperature-transient-to-burst tests of 9Cr-ODS TMS cladding tubes in the α-phase, α/γ-duplex, γ-phase matrices, which are accumulated by the Japan Atomic Energy Agency so far. The technique is adequately applicable to 9Cr-ODS TMS cladding tubes. A single high-temperature strength equation expressing the mechanical strength in different deformation and rupture modes (creep, tensile, temperature-transient-to-burst) is derived for 9Cr-ODS TMS cladding tubes. This equation can predict the rupture life of the cladding tubes under various stresses and temperatures over time. The applicable range of the high-temperature strength equation is specified in this study and the upper limit temperature for the equation is found to be 1200 °C. At temperatures higher than 1200 °C, the coarsening and aggregation of nanosized oxide particles and the γ to δ phase transformation are reported in previous studies. The high-temperature strength equation can be well applied to the creep and tensile strength in the α-phase matrix, the creep strength in the γ-phase matrix and the temperature-transient-to-burst strength in both phases except for the low equivalent stress (43 MPa) at temperatures exceeding 1050 °C. The mechanism of the notable consistency between creep and tensile strength in the α-phase matrix is discussed by analyzing the high-temperature deformation data in the light of existing deformation models. The study suggested the thermal activation process is dominant even for the high-temperature deformation modes exceeding yield stress in the 9Cr-ODS TMS with the fine-grained matrix.

Enhancing Hydrogen Sulfide Gas Detection: Tailoring ZnO Films Through a Novel Sol–Gel Approach with Ultra-Sonication

In this study, nano-sized Zinc Oxide (ZnO) particles were synthesized using a novel sol–gel process with Zn(NO3)2 solutions, specifically tailored for the development of a highly efficient Hydrogen Sulphide (H2S) gas sensing element. The impact of ultra-sonication on the properties crucial for H2S detection was systematically investigated. The resulting ZnO materials exhibited a well-defined crystalline structure along (100), (002), (101), and (102) planes, confirming the formation of the hexagonal wurtzite phase of ZnO. Significantly, an increase in sonication treatment time led to a reduction in particle size. The gas sensing properties for H2S were meticulously analyzed in relation to the varying sizes of ZnO films. Remarkably, the ZnO film fabricated with a 30-minute ultra-sonication treatment demonstrated the highest response to H2S gas at 423 K. The ZnO-thick films exhibited notable sensitivity, coupled with rapid reactivity and recovery times upon exposure to H2S gas. Importantly, our findings establish a direct correlation between the sensitivity of the ZnO sensor and the particle size.

Study of Precipitates in Oxide Dispersion-Strengthened Steels by SANS, TEM, and APT.

In this work, the nanostructure of oxide dispersion-strengthened steels was studied by small-angle neutron scattering (SANS), transmission electron microscopy (TEM), and atom probe tomography (APT). The steels under study have different alloying systems differing in their contents of Cr, V, Ti, Al, and Zr. The methods of local analysis of TEM and APT revealed a significant number of nanosized oxide particles and clusters. Their sizes, number densities, and compositions were determined. A calculation of hardness from SANS data collected without an external magnetic field, or under a 1.1 T field, showed good agreement with the microhardness of the materials. The importance of taking into account two types of inclusions (oxides and clusters) and both nuclear and magnetic scattering was shown by the analysis of the scattering data.

Nanotechnology's Application in Cosmetics: Dermatology and Skin Care Items

Nanotechnology has emerged as a revolutionary force in various fields, and its application in cosmetics has significantly transformed the landscape of dermatology and skin care. This abstract explores the multifaceted impact of nanotechnology on cosmetic products, focusing on its potential to enhance efficacy, improve delivery systems, and address specific dermatological concerns. Integrating nanotechnology into cosmetics offers a notable advantage by enabling precise control of materials at the nanoscale. This capability leads to the creation of formulations that exhibit enhanced bioavailability. The use of nano-sized particles, typically measured in nanometers, improves the penetration of active ingredients into the skin, ensuring precise delivery and increased absorption. This precision has paved the way for the development of highly effective skincare products capable of addressing specific skin conditions such as hyperpigmentation, fine lines, and acne. Furthermore, nanotechnology has revolutionized the formulation of sunscreens, offering transparent and cosmetically elegant options that provide superior protection against both UVA and UVB rays. Nano-sized titanium dioxide and zinc oxide particles scatter light more effectively, offering broad-spectrum coverage without the white residue associated with traditional sunscreens. Enhanced visual appeal motivates consistent application of sunscreen, fostering improved skin well-being and diminishing the likelihood of skin damage caused by sun exposure. In the realm of dermatology, nanotechnology has played a pivotal role in propelling forward groundbreaking therapeutic strategies. Nanoparticles are utilized to encapsulate and transport active components, including vitamins and antioxidants, ensuring their stability and prolonged release. This targeted approach allows for the customization of skincare regimens based on individual skin needs, thereby optimizing treatment outcomes for various dermatological conditions. Despite the remarkable advancements facilitated by nanotechnology, concerns have been raised regarding the safety of nano-sized particles in cosmetics. Addressing these concerns is crucial to ensure consumer confidence and regulatory compliance. Thorough testing and extensive research are crucial for a comprehensive evaluation of the safety characteristics of nanomaterials, taking into account factors such as particle size, surface charge, and potential interactions with the skin. In summary, the integration of nanotechnology into cosmetics marks a new era of innovation in dermatology and skincare. It not only enhances the delivery of active ingredients but also improves the effectiveness of sunscreens, presenting a promising path for the advancement of cutting-edge cosmetic formulations. As research in this field advances, it is essential to find a balance between innovation and safety, ensuring that nanotechnology continues to positively influence the cosmetics industry while prioritizing the well-being of consumers.

Nano-size cobalt-doped cerium oxide particles embedded into graphitic carbon nitride for enhanced electrochemical sensing of insecticide fenitrothion in environmental samples: An experimental study with the theoretical elucidation of redox events

In the present work, a nanocomposite, based on embedding Co-doped CeO2 nanoparticles into graphitic carbon nitride (g-C3N4), was applied to functionalize commercial glassy carbon paste. This is the first application of the electrochemical sensor, developed through the proposed procedure, in electrochemical sensing. The sensor was utilized for the electrochemical determination of organophosphate pesticide fenitrothion (FNT). Cyclic voltammetry identified reversible oxidation of FNT (oxidation at 0.18 V and reduction at 0.13 V) and additional reduction at −0.62 V vs. Ag/AgCl in HCl solution (pH = 1). Theoretical calculations were carried out to model and elucidate experimentally observed redox processes. Special attention was devoted to modeling experimental conditions, and based on the obtained results, a detailed redox mechanism of the investigated analyte was proposed. This represents the first complete and unambiguous elucidation of the FNT redox mechanism, supported by joined experimental and theoretical data. Square wave voltammetry (SWV) was utilized for quantification, whereby the FNT oxidation peak was chosen for monitoring the analyte concentration. The developed sensor provided a nanomolar detection limit (3.2 nmol L−1), a wide linear concentration range (from 0.01 to 13.7 μmol L−1), and good precision, repeatability, and selectivity towards FNT. Practical application possibility was explored by testing the sensor performance for examining tap water and apple samples. Recovery tests, conducted during the FNT-spiked sample assays, showed a great application capability of the developed sensor for real-time monitoring of FNT traces in environmental samples.

Impact of micro/nano cadmium oxide on shielding properties of cement–ball clay matrix

This study investigates the gamma radiation shielding properties of cement–ball clay matrix composites doped with micro- and nano-sized cadmium oxide (CdO) particles. The linear attenuation coefficient (LAC) was determined using a sodium iodide (NaI) detector and five radioactive point sources with energies ranging from 59.5 to 1408 keV. The LAC values obtained were compared to the XCOM database and found to be in good agreement. The composites' half-value layer (HVL), tenth value layer (TVL), mean free path (MFP), effective atomic number (Zeff), equivalent atomic number (Zeq), and absorption buildup factor (EABF) were determined. The results showed that the addition of CdO particles improved the radiation-shielding behavior of the composites and increasing the weight fraction of CdO particles increased the shielding effectiveness. The results also illustrated that when nano-sized CdO particles were compared to their micro-sized counterparts, there was a significant enhancement in radiation shielding effectiveness. For instance, a composite material composed of 50% cement, 41.7% ball clay, and 3.8% nano CdO at an energy level of 0.0595 MeV exhibited a remarkable 12.2% increase in attenuation, surpassing the performance of the micro-sized sample with an equivalent concentration. Similarly, another composite consisting of 50% cement, 33.3% ball clay, and 16.7% nano CdO demonstrated a significant 15.4% increase in attenuation at the same energy level, when compared to the micro-sized sample. The study demonstrates the potential of CdO-doped cement–ball clay matrix composites for gamma radiation shielding applications.

Mechanism to form nanosized oxides when burning aqueous carbohydrate salt solutions

This paper describes a method for the synthesis of nanosized oxide powders exemplified by Al2O3, MgO, and SiO2, which includes combustion of a saturated aqueous solution of salts and carbohydrates with multi-stage thermal treatment. A new approach to the synthesis of dispersed oxides with controlled properties has been developed. Particular attention is paid to the selection of optimal synthesis parameters (ratio of components, temperature, processing time) and analysis of phase transformations in the process of formation of nanosized powders with low bulk density. The stages of structural transformations of nanosized oxide particles during multistage heat treatment of an element-containing polymer matrix have been established. The synthesized Al2O3, MgO, and SiO2 nanoparticles are highly reactive due to their disordered defect structure.

Graded microstructure and mechanical properties of spark plasma sintered Fe-Cr alloys

Developing graded microstructure and mechanical properties is critical for accelerating the design and optimization of structural materials for a wide range of applications. In this study, Fe-Cr alloys were fabricated by spark plasma sintering (SPS) technique. The microstructure, microhardness, and tensile properties of the as-fabricated and thermally annealed variants were investigated. Graded grain structures were created in the as-fabricated cylinders along both axial and radial directions. Grain size was gradually reduced from the sample periphery to the center. Microhardness measurements reveal a gradual decrease of hardness towards the periphery of the samples. The as-fabricated Fe-Cr alloys show a desired combination of tensile strength and elongation, primarily due to the formation of a high density of oxides, voids, dislocations, and grain boundaries. After in-situ thermal annealing at 600 °C under 60 MPa for 2 h using SPS, the Fe-Cr alloys underwent minimal grain growth, and the graded grain structures were retained. The hardness was more uniformly distributed in the annealed variants, and the tensile strength was reduced with an increase in the total elongation, which is attributed to the dissolution of nano-sized oxide particles and the relief of the residual stress. This study demonstrates that SPS coupled with subsequent heat treatment can tailor the graded microstructure and control the mechanical properties of Fe-Cr alloys, showing potential applications in other alloy systems.

Preparation and properties of nano-MgO/HDTMS super hydrophobic multifunctional cotton

First, nano-sized magnesium oxide (MgO) particles were prepared with magnesium nitrate hexahydrate as raw material and plant extract Angelica dahurica as a protective agent and dispersant. Then, MgO nano particles (MgO NPs) were loaded on the cotton fabric surface by dipping method. Finally, using hexadecyl trimethoxysilane (HDTMS) as a modifier and ammonia as a catalyst, the cotton fabric was hydrophobically modified to prepare a super hydrophobic multifunctional cotton fabric. FTIR indicated that long carbon chain silane was successfully introduced onto cotton fabric. SEM and XRD analysis showed that the micro-nano rough structure was formed on the MgO/HDTMS/cotton fabric surface, and its crystal structure was unchanged. The water contact angle of cotton fabric modified by MgO/HDTMS reached 153°, which made it super hydrophobic. Moreover, MgO/HDTMS/cotton fabric has excellent antibacterial properties with the antibacterial rates against S. aureus and E. coli of 95.50% and 95.30%, respectively. After 10 times of cyclic washing, both the water contact angle and the antibacterial rate for S. aureus and E. coli of the fabric showed a slight decrease, which indicated that it has good washing durability.

A comparative evaluation of the effects of seed invigoration treatments with precursor zinc salt and nano-sized zinc oxide (ZnO) particles on vegetative growth, grain yield, and quality characteristics of Zea mays

IntroductionThe zinc micronutrient fertilizers have a critical impact on the grain productivity and quality attributes of maize. However, the low use-efficiency issues of the applied Zn-fertilizers are required to be addressed through the development of novel formulations and alternative application techniques.ObjectivesThis field study investigates the comparative impact of seed invigoration (including seed priming and coating) treatments with bulk zinc and ZnO nanoparticles (ZnONPs).MethodsThe two seed treatments with two different zinc sources at three different concentrations of 0, 20, and 40 mg L−1 each, for a total of ten treatments, were evaluated for vegetative growth, photosynthetic pigments, grain yield, and quality traits in Zea mays.ResultsThe total chlorophyll content was improved by ZnONPs seed priming at the V8 stage. However, there were plants that grew tall, bearing longer ears with bulk ZnSO4 and the untreated control. Yield-contributing factors like number of seeds per cob, and 1000-grain weight were marginally improved by ZnONPs treatment. Overall, only cob weight, starch, total soluble protein, and soil nutrient (N, P, K, and Zn) content were significantly enhanced by ZnONPs treatment. Furthermore, no negative effect was recorded on the soil microbiological and enzymatic activities seed treatment with both the zinc sources.ConclusionThe seed treatment, i.e. coating and priming with ZnONPs, did not significantly alter the grain yield, but the seed starch and total soluble protein content were improved.

Microstructural stability of a 9Cr oxide dispersion strengthened alloy under thermal aging at high temperatures

High temperature heat treatment is one of the critical steps in hot compression bonding (HCB), which was recently developed to scale up the fabrication of oxide dispersion strengthened (ODS) alloys. Understanding the microstructural evolution during heat treatments is required to refine the fabrication process to produce large-scale homogeneous ODS alloys. In this study, the effect of high temperature thermal aging treatments at representative temperatures (1000 °C and 1200 °C, respectively) on the microstructural stability of a 9Cr ODS alloy was investigated. The results show that the microstructure is relatively stable during thermal aging at 1000 °C up to 500 h. Within 50 h of aging at 1200 °C, δ-ferrite appears and its content increases with aging time. However, δ-ferrite completely disappears and hexagonal TiO2 particles with the size of 1–3 µm are uniformly distributed in the matrix after aging for 200 h. The nano-sized oxide particles coarsen slightly at 1000 °C, and the average size is ∼4.3 nm after aging for 500 h, whereas, significant coarsening takes place at 1200 °C after aging for more than 20 h, and the particle size increased from 3.76 nm at 20 h to 6.22 nm at 200 h. Additionally, the average grain size grows obviously after aging to 200 h. These results indicate that the HCB and hot working processes of 9Cr ODS alloy should be less than 20 h at 1200 °C or kept at lower temperatures to maintain the stability of nano-sized oxide particles and the overall microstructure.

An investigation on the plane-strain fracture toughness of a water atomized 4130 low-alloy steel processed by laser powder bed fusion

A water atomized 4130 steel powder was processed by Laser powder bed fusion and investigated both in as-built condition and after quench and tempering thermal treatment. Analyses were focused on the different microstructures developed and on steel fracture behavior in terms of tensile fracture elongation, Charpy impact properties, and linear elastic fracture toughness. Comparisons were also drawn by testing a reference 4130 steel fabricated from a gas atomized powder. The slightly higher oxygen content found in the water atomized powder led to the formation of finely dispersed nano-size oxide particles in the steel matrix. It was found that these inclusions have a minor effect on the tensile properties, but a significant influence on the impact toughness response. The fracture toughness tests showed that the orientation leading to propagation of cracks along the inter-layer planes represented the most critical situation, and the steel toughness could be significantly improved after the quench and tempering treatment owing to the achievement of a more homogeneous microstructure. The results suggest that the investigated water atomized low-alloy steel powder feedstock can be considered as a suitable and cheaper alternative for structural parts produced by additive manufacturing, which could replace the more popular gas atomized steel grades.

Mechanical Properties of Carbon Fiber/Epoxy Composites Modified with Micro- and Nano-Sized Magnesium Oxide Particles

A systematic study on evaluating the effect of micro- and nano-sized magnesium oxide (MgO) particles on the mechanical properties of carbon fiber/epoxy composites was conducted by adding various contents of MgO particles into an epoxy resin matrix. The impact and flexural strengths were determined by the Charpy impact tests and three-point bending experiments, respectively. We found that the carbon fiber/epoxy composites filled with nano-MgO particles had higher mechanical strength than that of the carbon fiber/epoxy composites filled with micro-MgO particles. Both impact and flexural strength were enhanced by adding the proper content of nano-MgO particles. Although the impact strength was increased by adding micro-MgO particles, the flexural strength was decreased by adding micro-MgO particles. In addition, the influence of the nano- and micro-particles on the failure modes of the fiber/epoxy composites was also studied and is described.

Ethanol gas sensing with lower temperature and higher response based on three-dimensional multilevel materials composed of micron hollow carbon spheres@SnO2 nanoparticles

Metal oxide semiconductor gas sensors (MOS) based on tin oxide have excellent performance in ethanol gas detection and have been widely used in industrial production, environmental protection, and road safety detection. However, conventional tin oxide sensors can only show excellent detection performance for ethanol gas above 250 °C. In this work, nano-size tin oxide particles were grown on the micron hollow carbon spheres derived from the biomaterial chlorella by a gel method. This three-dimensional hierarchical porous structure can enrich ethanol gas at a certain temperature. Ethanol gas sensor fabricated with this material has better sensing performance at low temperature (168–200 °C).