32 research outputs found
Identification and recovery of rare earth elements from electronic waste: Material characterization and recovery strategies
Full text linkThe sustained growth of the electronic and electrical industries necessitates not only efficient energy utilization throughout all manufacturing stages but also the recycling of end-of-life electric and electronic components. However, rapid advancements, miniaturization, and added value have led to a significant accumulation of e-waste, posing environmental concerns. Rare Earth Elements (REE) are considered critical raw materials that face a risk of global supply shortage due to their highly desirable performance-enhancing properties such as corrosion resistance. This study focuses on identification and exploring the recycling possibilities of different types of electronic waste for Rare Earth Materials. The electronic waste is first disassembled and categorized, after which material characterization techniques are employed to identify Rare Earth Elements (REEs). X-Ray Diffraction, X-ray fluorescence spectroscopy, Scanning Electron Microscopy, and Energy-dispersive X-ray spectroscopy are utilized for this identification. Subsequently, an in-depth review of existing literature is conducted to ascertain the most appropriate method for recovering these REEs. Neodymium and Dysprosium are among the REEs identified in the electronic waste samples.</p
The potential of utilising papaya seed oil and stone fruit kernel oil as non-edible feedstock for biodiesel production in Australia—A review
No full textAshwath, N ORCiD: 0000-0002-4032-4507; Nabi, M ORCiD: 0000-0002-4087-930X; Rasul, M ORCiD: 0000-0001-8159-1321This paper reviews and discusses the potential of papaya seed and stone fruit kernel biodiesels — the two sources of 2nd generation transport biodiesels in Australia. The challenges associated with biodiesel production and their possible solutions, particularly on feedstock selection, oil extraction, conversion of oil into biodiesel, biodiesel storage and transport, costs of production and the information needs for commercialising these sources of biodiesels are discussed, along with the eco-friendly attributes of these biodiesels to Australian transport sector. Some researchers report that the use of papaya seed and stone fruit kernel biodiesels reduce engine power only 2 to 5%), however significantly reduce harmful engine emission such as HC reductions of 9 to 19%, PM reductions of 19.5 to 35% and CO reductions of 11 to 29%. © 2019 The Author
EBSD characterization of Ag<sub>3</sub>Sn phase transformation in Sn–Ag lead-free solder alloys:a comparative study before and after heat treatment
No full textThe phase transformation and microstructural evolution of Sn–Ag solder alloys under heat treatment, with a focus on the Ag3Sn phase, were investigated to address the need for reliable lead-free solder alternatives in electronic packaging. Initially, the solder alloy exhibited a fine eutectic structure with well-dispersed Ag3Sn particles and a polycrystalline grain structure devoid of any strong crystallographic texture. Following heat treatment, significant microstructural changes were observed, including the coarsening of the Ag3Sn phase and the development of a preferred grain orientation, suggesting recrystallization and grain growth. XRD analysis revealed a decrease in the intensity of the Sn phase peaks and an increase in the coarseness of the Ag3Sn peaks post-heat treatment, indicating phase evolution and redistribution of silver within the alloy. The EBSD results supported the SEM findings, showing elongation and growth of grains and a shift in texture. These changes imply that heat treatment can significantly alter the mechanical properties of Sn–Ag solders, particularly affecting creep resistance and hardness due to the evolution of anisotropic mechanical properties. The study provides essential insights into the selection and optimization of solder materials for high-reliability applications in the electronics industry
Developing an a-/nc-Ge:H: film characterization and single-junction solar cell
No full textSingle junction solar cells have a theoretical efficiency limit of 33.1% due to spectral mismatch. To overcome this, multi-junction devices are generally fabricated with two or more junctions, so as to achieve better energy conversion efficiency by optimum spectral utilization. The c-Si bottom cell of a thin-film Si triple-/quadruple-junction device does not utilize the low energy photons (below 1.1 eV). The photons in the range of 0.7-1.1 eV, have an available current density of 15.9 mA/cm^2. A fraction of this current density would be large enough to not limit the output current of these thin-film Si-based multi-junction devices. Ge, belonging to the same group IV as Si and being heavier than it, forms weaker covalent bonds. Hence, it has a lower bandgap energy, making it the preferred choice of material. In this work, a low bandgap material such as a Ge-based absorber layer is fabricated that can be used in the bottom cell of a thin-film Si-based quadruple-junction device. This thesis will focus on the influence of a set of deposition parameters on the various properties of the Ge:H films. This will result in a set of Ge:H films from which a specific few are used as absorber layers to analyze the performance of a single-junction cell. The fabrication of the Ge:H films is carried out on a CASCADE setup which is based on the RF-PECVD technique. A processing range is identified to be in the range of 1-5 mbar pressure with RF powers ranging between 5-25 W for a fixed electrode distance of 20mm. nc-Ge:H are processed in the range of 20-25 W for pressures of 2 mbar and higher at a high dilution of 400. A strong correlation is found between the refractive index of the films and the presence of GeOx. The films with low refractive index possibly indicate a porous network with high void density show substantial oxygen contamination and vice-versa. Water vapour in the ambient is responsible for the oxidation. The oxygen contamination significantly impacts the properties of the films. The E04 optical bandgap increases with oxygen contamination which hinders the development of a low-bandgap absorber layer, while the Eact decreases to values as low as around 50 eV . Generally, the pre-exponential factor (sigma_o) decreases significantly by 1-5 orders of magnitude which outweighs the decrease in Eact, resulting in the decrease in dark conductivity by 1-3 orders of magnitude. Consequently, highest photo/dark conductivity ratios of 5-6 are obtained for these films. Amongst the films without oxygen contamination, the lowest E04 optical bandgap reported is 1.2 eV, with a Etauc bandgap of 0.93 and a photo/dark conductivity ratio around 3.4. Most of the single-junction cells processed at absorber layer thicknesses of 100nm and above show resistor-like behaviour. The substantially high values of Rs losses associated to the Rsh degrade the cell parameters significantly. Although, for low absorber layer thickness of around 50nm, the closest resemblance to a cell-behaviour is observed. Therefore, there is a scope for improvement with regards to processing of these single-junction cells.Electrical Engineering | Electrical Power Engineerin
mm-Wave Heatsink Antenna Array Design for Low-Sidelobe and Low-Temperature
No full textThe development of fifth-generation (5G) technology is the beginning of a rapid transition in the world of wireless communications. Gbps data rates, minimal latency, and good connectivity are the ultimate aims of 5G. To achieve them, 5G systems employ the mm-Wave frequency band which has a frequency range above 24GHz and so allows for higher bandwidth and gigabit wireless services. Because the size of the antenna elements and their spacings are so small in mm-Wave, massive antenna arrays in the base station may fit into a smaller area while yet providing high gain. However, the problem with the mm-Wave integrated antenna array system is the excessive heat generated per unit volume as there is not enough surface area to dissipate heat. Thermal management of the antenna system is very important as it affects the reliability and lifetime of the electronic components in the system. Both active and passive cooling strategies have been employed with passive cooling being the cost-effective and energy-efficient solution. Heatsink antennas can enhance the cooling capacity by providing dual functionality in terms of both thermal and electromagnetics. Traditionally, most of the works on heatsink antennas are focused at lower frequencies and a few at the mm-Wave frequency range. However, proper mm-wave thermal modeling in active integrated antennas is missing and there isn’t any research on the performance of heatsink antennas in array designs. This thesis work aims in designing and optimizing a heatsink antenna operating at 28 GHz to achieve dual functionality. The second aim of the thesis is to develop an appropriate thermal model for the designed antenna. Following the conduction-based simulations depending on assumed heat transfer coefficients, proper thermal modeling with appropriate beamformer chip characteristics and a CFD-based natural convective simulation setup has been developed without the assumption of a heat transfer coefficient. Optimal heatsink antenna dimensions are chosen based on the electro-thermal performance. Then, the selected antenna has been used in 1D and 2D arrays. Finally, a comparison study has been made with that of the conventional patch antenna. The results obtained have shown that both 1D (1x8) and 2D (4x4) heatsink antenna arrays can achieve a better heat dissipation by lowering the junction temperature of about 10-20 degrees Celsius (for the investigated cases) with higher realized gain and similar side lobe level compared to the respective patch antenna arrays. Furthermore, amplitude tapering of the heatsink antenna array achieved lower sidelobe levels which make this heatsink antenna a low-sidelobe and low-temperature alternative for the patch antenna array.Electrical Engineerin
The Effect of Prior Ferrite on Bainite Transformation Kinetics
No full textIn this work the effect of ferrite on the formation of bainite is studied. Different ferrite fraction of up to 25% were obtained through the application of three different intercritical annealing treatments to an Fe-0.2C-3Mn-2Si (wt%) steel. Two of the heat treatments consisted of an isothermal hold at temperatures between 835°C and 950°C, which was followed by slow cooling to a bainite formation temperature of 400°C. A third heat treatment included fast cooling from top temperatures between 810°C and 950°C to the same bainite formation temperature of 400°C. The heat treated material has been studied by means of dilatometry, optical microscopy, scanning electron microscopy and Vickers micro-hardness tests. All of the involved ferrite fractions had an accelerating effect on bainite formation, when compared to samples where no prior ferrite was present. The accelerating effect was larger for smaller prior ferrite fractions. It is proposed that the amount of preferential nucleation sites for bainite is increased by the formation of prior ferrite and leads to an acceleration of bainite formation. The presence of a significant amount of silicon (2 wt%) prevented the formation of cementite and resulted in carbon enrichment of austenite during ferrite formation. For the evaluated ferrite fractions, the accelerating effect due to ferrite presence is greater than the decelerating effect caused by the carbon enrichment of austenite, the latter becoming stronger with increasing ferrite fraction. Additionally, it is proposed that, due to the increase in preferential nucleation sites, a large amount of bainite sheaves start to grow simultaneously. Together with the autocatalytic nucleation of new bainite sub-units, this could account for the high bainite formation rates that were observed in the presence of ferrite. A change in bainite morphology from degenerated upper bainite to granular bainite with increasing prior ferrite fractions was also noticed. No significant difference in hardness was observed between the samples that contained prior ferrite, but the fully austenitised samples were slightly harder. It is expected that increasing ferrite fractions will result in a decrease in overall hardness, when macro-hardness tests would be applied
Comparison of oil refining and biodiesel production process between screw press and n-hexane techniques from beauty leaf feedstock
No full textAshwath, N ORCiD: 0000-0002-4032-4507; Rasul, M ORCiD: 0000-0001-8159-1321The Beauty Leaf Tree (Callophylum inophyllum) is regarded as an alternative source of energy to produce 2nd generation biodiesel due to its potentiality as well as high oil yield content in the seed kernels. The treating process is indispensable during the biodiesel production process because it can augment the yield as well as quality of the product. Oil extracted from both mechanical screw press and solvent extraction using n-hexane was refined. Five replications each of 25 gm of crude oil for screw press and five replications each of 25 gm of crude oil for n-hexane were selected for refining as well as biodiesel conversion processes. The oil refining processes consists of degumming, neutralization as well as dewaxing. The degumming, neutralization and dewaxing processes were performed to remove all the gums (phosphorous-based compounds), free fatty acids, and waxes from the fresh crude oil before the biodiesel conversion process carried out, respectively. The results indicated that up to 73% and 81% of mass conversion efficiency of the refined oil in the screw press and n-hexane refining processes were obtained, respectively. It was also found that up to 88% and 90% of biodiesel were yielded in terms of mass conversion efficiency in the transesterification process for the screw press and n-hexane techniques, respectively. While the entire processes (refining and transesterification) were considered, the conversion of beauty leaf tree (BLT) refined oil into biodiesel was yielded up to 65% and 73% of mass conversion efficiency for the screw press and n-hexane techniques, respectively. Physico-chemical properties of crude and refined oil, and biodiesel were characterized according to the ASTM standards. Overall, BLT has the potential to contribute as an alternative energy source because of high mass conversion efficiency. © 2016 Author(s)
Characterization Studies on Graphene-Aluminium Nano Composites for Aerospace Launch Vehicle External Fuel Tank Structural Application
Full text linkFrom the aspect of exploring the alternative lightweight composite material for the aerospace launch vehicle external fuel tank structural components, the current research work studies three different grades of Aluminium alloy reinforced with varying graphene weight percentages that are processed through powder metallurgy (P/M) route. The prepared green compacts composite ingots are subjected to microwave processing (Sintering), hot extruded, and solution treated (T6). The developed Nano-graphene reinforced composite is studied further for the strength−microstructural integrity. The nature of the graphene reinforcement and its chemical existence within the composite is further studied, and it is found that hot extruded solution treated (HEST) composite exhibited low levels of carbide (Al4C3) formations, as composites processed by microwaves. Further, the samples of different grades reinforced with varying graphene percentages are subjected to mechanical characterisation tests such as the tensile test and hardness. It is found that 2 wt% graphene reinforced composites exhibited enhanced yield strength and ultimate tensile strength. Microstructural studies and fracture morphology are studied, and it is proven that composite processed via the microwave method has exhibited good ductile behaviour and promising failure mechanisms at higher load levels
A Study on Technical Services of a R&D Institute with Special Reference to Customer Feedback and Satisfaction.
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Microstructural and mechanical behaviours of Y-TZP prepared via slip-casting and fused deposition modelling (FDM)
Full text linkThis paper reports the microstructural characteristics and mechanical properties of yttria-stabilized zirconia prepared via fused deposition modelling and slip casting. X-Ray Diffraction peaks indicated that yttria-stabilized zirconia crystallized in tetragonal structure for both slip casted(SC) and fused deposition modelled(FDM) samples. Further, scanning electron microscopy of slip casted sample showcased closely packed structure with fine grains and an average grain size of ∼65 nm whilst fused deposition modelled samples showcased non-homogeneous pores with ∼20 nm grain size. Average relative density of slip casted samples was ∼99.4 % while that of fused deposition modelled sample exhibited ∼96.2 %. The Vickers Hardness of slip casted (∼15.26 ± 0.4 GPa) was ∼10 % higher than the fused deposition modelled samples (∼13.79 ± 0.3 GPa). Likewise, indentation fracture toughness of slip casted (5.78 ± 0.5 MPa m1/2) was 14 % higher than fused deposition modelled samples which could have been due to the change in grain size as well as porosity of the ceramics. Compressive strength of the fused deposition modelled samples was 32 % less than slip casted samples (∼510 ± 10 MPa) due to its non-homogenous pores which led to weakening van der Waals force of attraction
