Materials Science for Energy Technologies最新文献

Nanoindentation technique is generally used for measuring thinfilm mechanical properties such as hardness, modulus and stiffness. Nanoindentation of ceramic thinfilms of SiO_2, Si₃N₄ and Al₂O₃ was deposited by radio-frequency (RF) magnetron sputtering on the stainless steel (SS304) substrates using a nanoindenter. Under varied sputtering conditions, the “as-deposited” film was amorphous. The as-deposited thin film had a thickness of 200 nm. The amorphous film was loaded/unloaded only once while operating in load control mode. Hardness and Young's modulus, two mechanical properties of the ceramic thinfilms, were also measured. When SiO₂, Si₃N₄, and Al₂O₃ thinfilms are deposited onto stainless steel substrates using an RF magnetron sputtering, the roughness of the ceramic thinfilms is in the range of 8 to 12 nm. The nanoindentation results were compared, the hardness of the coatings is in the range of 6 to 9 GPa, and these ceramic coatings can be used as an adhesive layer for multilayer thin film coating.

Today, the world’s power system is in transition towards “green” generation in line with the Paris climate agreement of 2015. Emergence of this technology alters existing consumption pattern for mineral resources. Today, center stage is taken by such crucial elements as copper, nickel, lithium, cobalt and, of course, REMs. Permanent REM magnets are pivotal to transition to green and renewable energy. Therefore, in new circumstances the global power system needs different approaches to production and supply chains for key natural resources. Russia’s FEC is the world’s second largest (after the USA) producer of power resources and third largest in-country consumer of the same (trailing the USA and China). However, there is no full-cycle production of individual REMs and REM-based alloys inside the country, despite one of the largest mineral resource bases of REMs in the world. A clearly apparent global trend shows that the pace of developing new MR sources and the necessary investments do not match acceleration in production of such high tech products as solar batteries, wind power generators (WPG), and electric cars. This is due to the fact that many key MRs (especially REMs) come from a small number of producers located in just a few countries. With this in mind, the paper presents a study of the production chain of NdFeB magnets and electric engines based on them, seen as essential to development of Russia’s wind power. Also, economic feasibility of some generation technologies in connection with the ever-increasing power of generators is considered. Basic topologies of electric machines are analyzed as well. The key question of the study is whether rare earth MRs become an incentive for transition to a new energy system in Russia or a bottleneck in the process.

Energy storing devices plays a major role in the development of technology. We synthesized carbon-based nanocomposites through a physical method and CuCo₂O₄ nanocomposites through a sol–gel technique calcined at 600 °C. From X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) confirmed the formation of CuCo₂O₄ nanocomposites which also shows some impurity phase of CuO nanoparticle. The average crystalline size found to be 45 nm. According to optical absorption analysis, the particles show maximum absorption in 256 nm and 369 nm in the UV region, while copper cobaltite doped with activated carbon (AC) shows broad absorption compared with copper cobaltite alone. Morphology studies shows agglomerate image in AC composites and hexagonal structures was formed in CuCo₂O₄ nanoparticles with average particle size of 100 nm. Atomic and weight percentages were recorded using energy dispersive X-ray analysis (EDAX). A good specific capacitance can be found from CV analysis, using electrochemical impedance spectroscopy (EIS), nanoparticles are shown to have different interface properties at the surface of electrodes. Using CuCo₂O₄ and its composite as positive and negative electrodes in cyclic voltammetry (CV) studies shows excellent electrochemical properties. In addition, CuCo₂O₄ with activated carbon is promising as a low-cost and good supercapacitor material.

Using first-principles calculations, in this piece of work, authors have investigated the physical properties of Ra₂LaNbO₆ double perovskite by employing the linearized augmented plane wave (LAPW) method. Structural and electronic properties are determined by using LDA, GGA (WC and PBE), LDA + mBJ, and GGA + mBJ potentials. We have found that Ra₂LaNbO₆ is an indirect band gap (E_g = 2.4 eV) semiconductor. Its elastic and thermodynamic parameters demonstrate its stability. Its optical study indicates that this material opens the door to its applications in optical devices such as photodetectors, solar cells, superlenses, optical fibers, filters, electromagnetic shielding devices, photovoltaic devices, etc. This material is very good for its practical implementation in thermoelectric devices as both p- and n-type material and extends the interest of experimentalists for further investigations. Thus, Ra₂LaNbO₆ is found thermodynamically stable and identified as a potential candidate for photovoltaic and thermoelectric devices.

Modern engineering applications continually strive to develop greater performance mechanical components with good microstructural stability, improved mechanical properties, corrosion resistance and decreased cost of repairing and maintenance. This necessitates the broad use of advanced high performance materials like high entropy alloys (HEAs). These alloys are created by combining five or more alloying elements in equal or substantial amount. About 5 to 35 at. % of the alloying element is present in HEAs. It is characterized primarily by greater entropy, slow diffusion, severe lattice distortion, and cocktail effects. Due to its advanced microstructural stability throughout a larger temperature span and for longer length of time, it demonstrates improved mechanical characteristics at ambient temperature, cryogenic temperature, and elevated temperature. The diversity of elemental contents and significantly higher mixing entropy of HEAs make them mechanically superior to classic metals and alloys. It also shows better strength to weight ratio. Hence, it qualifies as a possible structural and functional material for aeroengine applications. In this work, the studies on the HEAs are briefly reviewed. A basic explanation of the four core effects of HEAs is given. Discussion is held on microstructure and mechanical properties of HEAs. The processing routes for manufacturing of HEAs (arc melting, bridgman solidification, mechanical alloying and vapour deposition) are presented briefly. The influence of heat treatment on mechanical behavior and microstructure of HEAs is presented. The simulation approach of CALPHAD modeling for designing of HEAs is discussed briefly. The future scope for research and development of HEAs in aeroengine applications is briefed.

Nano-silicon is synthesized by hydrothermal method from rice husk, which has the advantage of using low temperature in an autoclave at 180 °C. Reduction of silica using a mixture of silica gel extracted from rice husks with Mg powder. The silica gel and Mg powder reaction produces nano-silicon. XRD diffractogram, it can be seen that Si-0.5, Si-0.6, and Si-0.7 form hkl (1 1 1), (2 2 0), (3 1 1), (4 0 0), (3 3 1), and (4 2 2). Raman spectra show peaks at the Raman shift of 520 cm⁻¹, XPS spectrum high scan Si2p peaks at 99 eV, indicating silicon, and at 103 eV, the oxide layer on nano-silicon. The isotherm adsorption graph using the BET method type IV isotherm graphs with surface areas are 18.60 m²g⁻¹ until 20.39 m²g⁻¹. Pore size using the BJH method shows 1.69 nm until 8.30 nm. SEM and TEM nano-silicon morphology images, the shape of the nano-silicon is spherical. The nano-silicon formed produces high-performance anode lithium-ion batteries with a discharge capacity of 1757 mAh g⁻¹, above 1000 mAh g⁻¹ for approximately 200 cycles.

The experiment was carried out by growing BaTiO₃ (Undoped or Li-doped) on p-type Si_(1 0 0) substrates using the Chemical Solution Deposition (CSD) method and spin coating at a rotational speed of 3000 rpm for 60 s, followed by heating at 850 °C. The characterization results show that the bandgap energy value of the thin film due to lithium doping reduces the bandgap energy value. This is presumably because the donor atom added to a semiconductor causes the allowable energy level to be slightly below the conduction band. The presence of this new band causes the thin film bandgap energy to decrease with a five-valent tantalum dip. The morphological properties showed that the BaTiO₃/Si_(1 0 0) thin film particles in the deposited lithium had a fairly homogeneous grain. With the addition of lithium acetate as a binder into barium titanate, the grain size is getting smaller because it is suspected that the lithium-ion radius is smaller than the barium-ion radius. Measurement of I-V on the thin film shows that the output voltage value increases with more light intensity hitting the surface of the thin film. The greater the light intensity, the greater the energy of the photons, so the electrons are easier to jump. The three things above (both electrical and morphological properties) conclude that the thin films grown have the potential for photovoltaics.

Recent concerns regarding climate change and rising energy costs have dramatically increased interest in using alternative energies, especially biomass energy which is carbon neutral. Hemp is among the fastest-growing plants with unique fiber characteristics. The objective of this study was to investigate the physical and chemical properties of hemp stalks of seven different clones and to assess their feasibility as a sustainable bioenergy resource. Seven clones (KU03, KU18, KU27, KU45, KU49, RPF1, and RPF2) of four-month-old hemp (Cannabis sativa) were used in this work. Physical properties, volatile content, fixed carbon, ash content, calorific value, chemical composition, ash composition, and metal element of the samples were investigated. The results revealed that hemp stalk had desirable fuel characteristics with high volatile substance, high heating value, low ash content, very low nitrogen content, and non-detectable sulfur. Selecting well-adapted clones and appropriate technology which can convert the hemp stalks to suitable bioenergy forms are important aspects of bioresource management. Based on our findings, some selected hemp clone biomass possessed excellent characteristics and great potential to be used as raw material for bioenergy production.

Different polylactic acid (PLA) thin films containing clarithromycin and a number of metal oxide nanoparticles (magnesium, titanium, zinc, and nickel) dioxides were created. Low dosages of metal oxides (0.01% by weight) and clarithromycin (0.5% by weight) were used to make transparent films. The role of metal oxide nanoparticles and clarithromycin as UV blockers for PLA photodegradation was looked at. The durability of polymeric materials is improved more by clarithromycin in combination with metal oxides than by clarithromycin alone in PLA films. An analysis of the weight loss, surface morphology, and changes in infrared spectra of irradiated polymeric blends revealed that nickel oxide and clarithromycin together function as effective UV blockers and offer PLA a high degree of protection. Nickel oxide nanoparticles were the best addition for PLA stability. Highly alkaline metal oxides are present. Contrarily, the heteroatom and aromatic nature of clarithromycin enables it to absorb damaging radiation and function as an ultraviolet absorption. Thus, the adaptability of PLA to photodegradation was significantly improved by using a mixture of metal oxide nanoparticles and clarithromycin.