Variation Of Layer Thickness Research Articles

Comprehensive performance analysis of perovskite solar cells based on different crystalline structures of MAPbI3

Perovskite solar cells (PSCs) have shown high optical absorption and consequently provide high conversion efficiency with stable performance. In our work, CH3NH3PbI3 (MAPbI3) as an absorber layer is analyzed for different crystalline structures. Cubic, tetragonal, and orthorhombic phases of perovskite material are investigated to check the impact of the crystalline structure on the solar cell performance. Both density of states and band structure are studied using Quantum-ESPRESSO package depending on density functional theory. Then, all relevant parameters were employed in SCAPS software and comprehensive study was done for examining the effect of the crystalline structure of perovskite layer on the solar cell performance. In-depth, analyses were conducted to evaluate key parameters, including open circuit voltage (Voc), short circuit current (Isc), fill factor (FF), and power conversion efficiency (PCE) considering the variations of perovskite layer thickness and bulk defect densities. The obtained results indicate that cells with cubic MAPbI3, which shows a notably higher bandgap of 1.7 eV and an enhanced optical absorption coefficient, especially in the higher wavelength range (around 105 cm−1), show better performance for almost all three scenarios. Cubic MAPbI3 cells achieve relatively higher peak efficiency of 26% when the absorber layer thickness is almost 900 nm. The investigation into absorber bulk defect densities reveals the critical role of defect levels in PSC performance. Adjusting defect levels from 1014 cm−3 to 1018 cm−3 results in deteriorating trends in Voc, Jsc, FF, and PCE. Jsc remains stable until a defect level of 1017 cm−3, highlighting a threshold where defects begin to impact charge carrier generation and separation. Doping effect has been studied, PCE remains stable until a critical doping level of 1016 cm−3 after which it drops significantly which indicates that doping is cautioned against due to its adverse effects on material and carrier transport. This finding holds significant promise for experimental solar cell fabrication, as it suggests that cubic MAPbI3’s superior bandgap and enhanced optical absorption could lead to more efficient and robust photovoltaic devices in real-world applications.

Effect of oxidation temperature on physical properties of polycrystalline β-Ga2O3 grown by thermal oxidation of GaN in O2 ambient from 900 to 1400 °C

This study aimed to investigate the effect of oxidation temperature on the physical properties of β-Ga2O3 grown by thermal oxidation of GaN in the O2 ambient at high oxidation temperatures from 900 to 1400 °C. Notably, the analysis of the oxidation temperatures ranging from 1100 to 1400 °C remains unexplored in the other studies. The effects of the oxidation temperature on the physical properties were investigated via X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy (FESEM). At all oxidation temperatures, XPS results revealed oxygen deficiency. The top FESEM images indicated disordered nanocolumn structures on the surface of the oxide layer, which increased in abundance with oxidation temperatures exceeding 1100 °C. Energy-filtered high-resolution transmission electron microscopy images and the selected area electron diffraction patterns revealed that the top nanocolumns and the oxidized layer comprised polycrystalline β-Ga2O3. Additionally, the cross-sectional lamellae prepared through focused ion beam milling revealed an increase in the thickness of the β-Ga2O3 layer with oxidation temperature. To account for the variations in the oxide layer thickness, the oxidation temperatures were classified into two ranges of 900–1100 °C and 1100–1400 °C for calculating the activation energy. Moreover, this study assumed that the activation energy required for the oxidation process remained constant within each temperature interval. According to Arrhenius's model, the activation energy from 900 to 1100 °C was calculated to be 286.15 kJ/mol (2.97 eV). Furthermore, the activation energy from 1100 to 1400 °C was determined to be 111.33 kJ/mol (1.15 eV).

Sequentially PVD‐Grown Indium and Gallium Selenides Under Compositional and Layer Thickness Variation: Preparation, Structural and Optical Characterization

AbstractGroup IIIA metal chalcogenides are an auspicious material system due to their variability of properties and hence the multitude of application options, for example, in the fields of optoelectronic, thermoelectric, piezo‐, and ferroelectric devices. Indium and gallium selenide films are innovatively grown in a sequential PVD (physical vapor deposition) process starting from metal precursor layers of various thicknesses, which are then subject to chalcogenization in different selenium contents. The resulting thin films are investigated for structural and optical properties by Raman, XRD (X‐ray diffraction), and UV–Vis–NIR spectrometry, revealing that all the compounds In2Se3, InSe, In4Se3, Ga2Se3, and GaSe as well as different polytypes can be achieved depending on the metal/chalcogen ratio. Results from Raman and XRD spectroscopy are highly consistent, and also from the optical measurements changes in absorption characteristics can be correlated. The results indicate, that by fine‐tuning the selenium content, deliberately growing ultra‐thin layers of the different indium and gallium phases will be possible, thus opening up a promising route for 2D material fabrication. Given the scalability of the fabrication method, it is highly promising for large‐scale deployment of the materials.

The Influence of Environmental Temperature on the Passive Oxidation Process in the C/SiC Composite

The C/SiC composite plays a crucial role in providing thermal protection for hypersonic vehicles. The SiO2 oxide layer formed via passive oxidation during ablation constitutes a typical porous medium with self-similarity. Given its significant impact on the thermal protection of the material, accurately predicting the variation in the SiO2 oxide layer thickness is of paramount importance. The growth of the oxide layer impedes the diffusion of oxygen within the material. This study considered microstructural parameters of the oxide layer based on high-temperature gas oxidation tests of the C/SiC composite. Fractal theory was utilized to construct a fractal diffusion-reaction kinetics model describing oxygen diffusion within the oxide layer and the evolution of the oxide layer under varying environmental conditions. The finding demonstrated that the existence of the oxide layer significantly influences the passive oxidation of the composite. This study underscored the significance of predicting the impact of environmental parameters on passive oxidation in the practical application of the C/SiC composite and the study result offers a valuable reference for evaluating the thermal resistance of the C/SiC composite.

Conceptual Model of Permafrost Degradation in an Inuit Archaeological Context (Dog Island, Labrador): A Geophysical Approach

Characterizing permafrost is crucial for understanding the fate of arctic and subarctic archaeological archives under climate change. The loss of bio-physical integrity of archaeological sites in northern regions is still poorly documented, even though discontinuous permafrost is particularly vulnerable to global warming. In this study, we documented the spatial distribution of the permafrost-supported Inuit archaeological site Oakes Bay 1 on Dog Island (Labrador, Canada) while employing a novel approach in northern geoarchaeology based on non-invasive geophysical methods. ERT and GPR were successfully used to estimate active layer thickness and image permafrost spatial variability and characteristics. The results made it possible to reconstruct a conceptual model of the current geocryological context of the subsurface in relation to the site topography, hydrology, and geomorphology. The peripherical walls of Inuit semi-subterranean sod houses were found to contain ice-rich permafrost, whereas their central depressions were identified as sources of vertical permafrost degradation. The geophysical investigations were used to classify the permafrost at Oakes Bay 1 as climate-driven, ecosystem-protected permafrost that cannot regenerate under current climate conditions. This work highlights how the permafrost at Oakes Bay 1 is currently affected by multi-point thermal degradation by both conduction and advection, which makes it highly sensitive to climate warming.

A novel layer-based optimization method for stabilizing the early printing stage of LPBF process

ABSTRACT The laser power bed fusion (LPBF) forming process introduces heat accumulation and variations in powder layer thickness, which can destabilize the melt track and reduce surface quality. This phenomenon is especially more serious in the early printing stage. To tackle this stability problem, we proposed a novel approach optimizing process parameters on a layer-specific basis. At first, a numerical database was constructed through a set of numerical simulations. Then, a neural network prediction model was trained based on the database. Finally, this prediction model was embedded into a genetic algorithm for layer-based prediction. To verify the prediction results on processing parameters and calibrate the prediction model, physical experiments were prepared. The developed model consistently exhibited relative errors mostly within 6%. It is noteworthy that the relative errors between the numerical simulation results and the expected values were only 0.77% in width and 1.11% in depth. Printing optimization test was applied for an LPBF machine with a Invar alloy powder. The proposed method yielded positive results in both numerical simulations and the printing test. It can be further adopted for new material printing parameter optimization due to an efficient printing stability in the early-stage for LPBF process.

Adaptive integral sliding-mode finite-time control with integrated extended state observer for uncertain nonlinear systems

For the typical uncertain nonlinear systems subjected to controller gain variation and disturbances, an integrated adaptive robust controller, called integral sliding-mode finite-time controller with an integrated extended state observer (ISFC-IESO), is proposed. The designed controller mainly consists of an integrated ESO (IESO) unit and an integral sliding-mode control (ISMC) unit. The IESO unit is composed of improved linear and nonlinear ESOs which are designed to automatically switch each other, with the aim of enhancing disturbance estimation capability. Moreover, the ISMC unit produces an integral sliding-mode control law (SMCL) based on the newly designed integral sliding-mode surface function (SMSF) and sliding-mode reaching law (SMRL). The integral SMSF is developed based on the n-th estimated state and a designed convergence function of tracking error to suppress the influence of the disturbance estimation error. On this basis, SMRL is further presented by combining integral SMSF with a specially designed variable boundary layer thickness saturation function, for the purpose of eliminating chattering and enhancing robustness. Finally, fourteen control methods are compared to illustrate the effectiveness and superiority of the proposed ISFC-IESO.

Use of Distributed Fiber Optic Sensors for the Monitoring of an Accelerated Pavement Test

The need to develop more efficient pavement management systems has driven continuous improvement in structural health monitoring (SHM) systems for road infrastructures. Factors such as low energy consumption, minimal disruption (small-sized and lightweight devices), resistance to environmental conditions, high durability, and sensitivity are some of the possible improvements worthy of exploration. Fiber optics appear to have several of these desired characteristics. In this context, this article presents strain measurements performed using fiber optic cables installed at various levels in pavement structures tested on the accelerated pavement testing facility at the Université Gustave Eiffel (or fatigue carousel). The results reveal that strains measured with this technology closely align with those obtained using traditional strain gauges. However, an advantage of fiber optics is that they enable distributed measurements over long distances with high precision (10 m with a measurement interval of 2.6 mm in this study). These measurements highlight a significant variability in pavement strains, seemingly attributable to the heterogeneity of pavement materials and variations in layer thicknesses. As a result of these findings, laboratory-scale investigations have been initiated to gain a better understanding of these sources of variability.

Sensitivity analysis of inverted model parameters from transient electromagnetic measurements affected by induced polarization effects

We investigate the application of the distance-based global sensitivity analysis (DGSA) to evaluate the sensitivity of electrical model parameters obtained from transient electromagnetic (TEM) data including induced polarization (IP) effects. We propose novel open-source forward modeling and inversion routines for single-loop TEM data including IP effects with the maximum phase angle model to model the frequency dependence of the complex resistivity. In a first step, we evaluate the accuracy of our forward modeling and inversion routines using numerical studies, where the actual variations of layer thicknesses and resistivities, as well as the frequency dependence of the complex resistivity is known. In a second step, we extend our investigation to field data and apply our approach to three distinct case studies in layered media: 1) a confined aquifer corresponding to conductive non-polarizable media, 2) a graphite deposit corresponding to highly conductive and polarizable anomalies in a resistive host rock and 3) an ice glacier corresponding to highly resistive polarizable media. Our DGSA results reveal that standard depth of investigation (DOI) approaches may overestimate the true sensitivity of the model obtained from the inversion. TEM data collected in conductive layered media without IP effects show reduced sensitivity above the predicted DOI. The case studies in polarizable media demonstrate that the maximum phase angle is more influential on the TEM model response than the relaxation time and dispersion coefficient. Our DGSA results for polarizable media reveal that TEM field data collected at the graphite deposit and at the ice glacier are sensitive to the geometry of the polarizable layer.

Effects of background doping, interdiffusion and layer thickness fluctuation on the transport characteristics of THz quantum cascade lasers

In this work, we investigate the effects of n and p-type background doping, interface composition diffusion (interdiffusion) of the barrier material and layer thickness variation during molecular beam epitaxy (MBE) growth on transport characteristics of terahertz-frequency quantum cascade lasers (THz QCLs). We analysed four exemplary structures: a bound-to-continuum design, hybrid design, LO-phonon design and a two-well high-temperature performance LO-phonon design. The exemplary bound-to-continuum design has shown to be the most sensitive to the background doping as it stops lasing for concentrations around 1.0·1015\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1.0\\cdot 10^{15}$$\\end{document}–2.0·1015\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$2.0\\cdot 10^{15}$$\\end{document} cm-3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{-3}$$\\end{document}. The LO-phonon design is the most sensitive to growth fluctuations during MBE and this is critical for novel LO-phonon structures optimised for high-temperature performance. We predict that interdiffusion mostly affects current density for designs with narrow barrier layers and higher Al\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{Al}$$\\end{document} composition. We show that layer thickness variation leads to significant changes in material gain and current density, and in some cases to the growth of nonfunctional devices. These effects serve as a beacon of fundamental calibration steps required for successful realisation of THz QCLs.

Investigating of novel inorganic cubic perovskites of A3BX3 (A=Ca, Sr, B[dbnd]P, As, X=I, Br) and their photovoltaic performance with efficiency over 28%

Inorganic halide perovskite-based compounds of A3BX3 have been gaining huge attention during the development of high-efficiency solar cells (SC) in recent years. This paper, investigating the physical and chemical properties could unveil its further potential to be used as absorber materials in advanced multijunction photovoltaics. The structural, optical, and electronic characterization of different compositional compounds of A3BX3 (A=Ca/Sr, BP/As, X=I/Br) perovskites are examined thoroughly to be used as absorber in high performance photovoltaics. The DFT study reveals direct bandgaps of 1.93 (2.60) eV, 1.58 (2.14) eV, 1.96 (2.63) eV, 1.58 (2.16) eV, 1.52 (2.30) eV, 1.26 (1.94) eV, 1.53 (2.32) eV, and 1.26 (1.96) eV at Γ for the Ca3AsBr3, Ca3AsI3, Ca3PBr3, Ca3PI3, Sr3AsBr3, Sr3AsI3, Sr3PBr3, and Sr3PI3 perovskites using PBE (HSE) methods with optical absorption of (2−5)x104 (a. u.) in the optical region (< 3.2 eV). Subsequently, the potential of the A3BX3 absorber has been investigated and analyzed at varying layer thickness, defect densities, and doping concentrations with SnS2 electron transport layer (ETL) layer using FTO/SnS2/A3BX3/Ni heterostructure with current density-voltage (J-V) characteristics and corresponding quantum efficiency (QE) observation. The power conversion efficiency (PCE) of 13.52, 20.88, 13.66, 22.47, 20.83, 28.16, 20.77, and 27.32% were achieved in Ca3AsBr3, Ca3AsI3, Ca3PBr3, Ca3PI3, Sr3AsBr3, Sr3AsI3, Sr3PBr3, and Sr3PI3 absorber-based heterojunction SC. Notably, the highest PV performance revealed a PCE over 28% with a VOC of 0.913 V, JSC of 35.75 mA/cm−3, and FF of 86.26% obtained in the Sr3AsI3 absorber SCs. Thus, these detailed studies on the physical and optoelectronic properties of eight (8) different possible absorber-based configurations including their PV applications unveil the huge potential of A3BX3 (i.e., Sr3AsI3) and provide resources for the practical cell development of inorganic perovskites-based high efficiency SC over 28%.

Peripapillary retinal nerve fibre layer thinning, perfusion changes and optic neuropathy in carriers of Leber hereditary optic neuropathy-associated mitochondrial variants

BackgroundWe investigated Leber hereditary optic neuropathy (LHON) families for variation in peripapillary retinal nerve fibre layer thickness and perfusion, and associated optic nerve dysfunction.MethodA group of LHON-affected patients (n=12) and...

Spatiotemporal characteristics and variability in the thermal state of permafrost on the Qinghai–Tibet Plateau

AbstractPermafrost degradation on the Qinghai–Tibet Plateau (QTP) has significant impacts on climate, hydrology, and engineering and environmental systems. To understand the temporal and spatial characteristics of permafrost on the QTP, we quantified the variation in active layer thickness (ALT), permafrost thermal state, and future permafrost change under different scenarios using observational data, reanalysis data, and the numerical permafrost model. Generally, ALT ranged from 0.5 to 6.0 m with an average of 2.39 m, and mean annual ground temperature (at a depth of zero annual amplitude for ground temperature) mainly ranged between 0 and −3°C with an average of −0.85°C. The soil temperatures in different layers based on the ERA5‐Land data revealed even stronger increasing trends, for example, 0.245, 0.245, 0.244, and 0.238°C/decade at depths of 0–7, 7–28, 28–100, and 100–289 cm from 1980 to 2021, compared to those during the period from 1960 to 2021, which were 0.153, 0.156, 0.155, and 0.149°C/decade, respectively. The average warming trends in annual mean soil temperature were 0.153 and 0.243°C/decade from 1960 to 2021 and 1980 to 2021, respectively. The average rate of thickening of the ALT among the 10 active layer observation sites was 2.84 cm/year. There was a significant warming trend in ground temperature above ~15 m with warming of 0.063 to 0.120, 0.026 to 0.182, 0.101 to 0.314, and 0.189 to 0.303°C/decade at the QTB01, QTB06, QTB08, and XDTGT sites, respectively, and yearly minimum ground temperatures exhibited stronger warming trends than maximum ground temperatures. In addition, the simulation revealed significant increases in ground temperature at the Xidatan (XDT) and Tanggula (TGL) sites under both historical and future Representative Concentration Pathway (RCP) scenarios, but the increases in ground temperature were significantly greater at TGL than XDT. These findings provide important information for understanding the variability in permafrost degradation processes and improving simulations of permafrost change under climate change on the QTP.

Investigating inorganic perovskite as absorber materials in perovskite solar cells: machine learning analysis and optimization

This work investigates the potential of inorganic perovskites AgBiSCl2 and Al2Cu2Bi2S3Cl8 as absorber layers in perovskite solar cells, followed by the application of supervised machine learning models. Extensive exploration and optimization of device architectures FTO/SnO2/AgBiSCl2/Spiro-OMeTAD/Au and FTO/SnO2/Al2Cu2Bi2S3Cl8/Spiro-OMeTAD/Au are conducted, involving variations in absorber layer thickness (d), bulk defect density (Nt), and carrier mobility (μ n,p). The AgBiSCl2-based device achieves an optimized conversion efficiency of 10.06%, while the Al2Cu2Bi2S3Cl8-based device achieves 12.27%. To train different machine learning models, 1600 datasets are collected for each device, and Neural Networks (NN), Random Forests (RF), and XGBoost (XGB) models are employed. The performance parameters, evaluated using mean squared error (MSE) and high R-squared (R2) values, demonstrate that XGB performs the best, achieving an MSE of 0.210 and R2 of 97.1% for AgBiSCl2 and 0.671 and 90.6% for Al2Cu2Bi2S3Cl8. Additionally, the impact of each variable (d, Nt, and μ n,p) on the output is analyzed using Shapley Additive Explanations (SHAP) plots for each model. The results presented in this study pave the way for the advancement of perovskite material-based solar cells without relying on complex optoelectronic semiconducting equations and device simulators.

Heat generating impact on radiative nanofluid flow via exponential expanding surface with convective conditions: Mesh independence examination

The current article aims to inspect existence of electrical field in magnetohydrodynamics stream of nanofluid toward nonlinear via various thicknesses of symmetric extended surface. This examination is distinctive in that it analyses influences of Joule heating, thermal radiation, and chemical reaction on heat and mass transport. Electric field and variable thickness phenomena are used to study thermophysical properties. Asymmetry technique is used to describe geometric model. Governed differential equations are changed over into dimensionless ordinary differential equations by applying similarity changes and solutions are obtained by bvp4c in MATLAB. Augmentation in velocity and temperature, together with suppression of concentration is caused by occurrence of electric field. Parameters of magnetized force, thermal radiation, and Eckert number are responsible for enhancing variations in temperature and thermal boundary layer thickness. These variations are reduced with rising Prandtl number and electric field. This research compares new findings with preexisting data in limited cases.

Optimization of Perovskite/Colloidal Quantum Dot Monolithic Tandem Solar Cell to Enhance Device Performance via Solar Cell Capacitance Simulator 1D

Tandem solar cells (TSCs) based on metal halide perovskites offer a route to increase power conversion efficiency (PCE). However, there are limited options for narrow‐bandgap bottom subcells. Colloidal quantum dots‐based solar cells are found attractive for this role. Herein, a cost‐effective two‐terminal (2T) monolithic TSC structure consisting of wide‐bandgap all‐inorganic perovskite top subcell and narrow‐bandgap chalcogenide PbS quantum dots bottom subcell is proposed. For optimization of the PCE of the tandem structure, standalone and tandem analysis are done in terms of variation of absorber layer thickness, total defect density, interfacial defect density, back metal contact, current density voltage (J–V) curves, external quantum efficiency, current matching, and tandem photovoltaic parameters. Optimized TSCs designed with the 530 nm/450 nm‐thick absorber layers of top/bottom sub cells result in of 19.28 mA cm−2, of 1.89 V, and PCE of 27.32%. It is found that performance of the device is very sensitive to the total defect density of the bottom subcell. Therefore, high PCE can be obtained by controlling the total defect density of the bottom subcell. This work motivates the experimental realization of low‐cost, high‐efficiency TSCs for further research.

A data-driven polynomial chaos method for uncertainty quantification of a subsonic compressor cascade with stagger angle errors

The probability-based uncertainty quantification (UQ) methods require a large amount of sampled data to construct the probability distribution of uncertain input parameters. However, it is a common situation that only limited and scarce sampled data are available in engineering applications due to expensive tests. In the present paper, the Data-Driven Polynomial Chaos (DDPC) method is adopted, which can propagate input uncertainty in the case of scarce sampled data. The calculation accuracy and convergence of the self-developed DDPC method are validated by a nonlinear test function. Subsequently, the DDPC method is applied to investigate the uncertain impact of stagger angle errors on the aerodynamic performance of a subsonic compressor cascade. A family of manufacturing error data of stagger angles was obtained from the real compressor blades. Based on the limited measurement data, the DDPC method combined with Computational Fluid Dynamics (CFD) simulation is employed to quantify the performance impact of the compressor cascade. The results show that the performance dispersion under off-design conditions is more prominent than that under design conditions. The actual aerodynamic performance deviating from the nominal performance is not a small probability event, and the probability of deviating from the nominal loss coefficient and exit flow angle by more than 1% can reach up to 47.6% and 36.8% under high incidence i = 7°. Detailed analysis shows that stagger angle errors have a significant effect on the flow state near the leading edge, resulting in variations in separation bubble size and boundary layer thickness.

Magnetic domain structure of iron-based microwires after removal of the glass shell by chipping and chemical etching

The magnetic domain structure of the surface of microwires with composition Fe73.9B13.2Si10.9C2 was studied by magnetic force microscopy. It has been found that the removal of glass shell by chipping leads to distortion of the original magnetic domain structure. Chemical etching of the glass shell makes it possible to observe the magnetic domain structure due to the stresses that have arisen due to the microwire production. In the absence of an applied magnetic field, a magnetic domain structure of the surface layer is observed, consisting of domain layers inclined to the microwire axis by 45 or 135 degrees. This structure has a shape close to a zigzag. The thickness of the domain layers is not constant and varies from 3 to 5 μm. It has been found that the application of a constant magnetic field along the microwire axis causes the formation of ring domain layers of various thicknesses (from 1 to 5 μm) with different orientations of the magnetic moment relative to the microwire surface. In a field of 60 oersteds along the axis of the microwire, the domain magnetic structure consists of only ring layers of domains. Magnetic field inversion leads to almost complete inversion of the observed domain structure. In this case, the complete removal of the magnetic field leads to the formation of a new domain structure of the surface layer. Such a structure is close in shape and position of the domains to the original one, but does not repeat it.

The Effects of Layer Thickness on the Mechanical Properties of Additive Friction Stir Deposition-Fabricated Aluminum Alloy 6061 Parts

Solid-state additive friction stir deposition (AFSD) is a thermomechanical-based additive manufacturing technique. For this study, AFSD was utilized to produce aluminum alloy 6061 (AA6061) blocks with varying layer thicknesses (1 mm, 2 mm, and 3 mm). The mechanical properties were assessed through uniaxial tensile tests and Vickers microhardness measurement, and statistical analysis was employed to investigate differences among data groups. The results revealed that the deposition layer thickness influences tensile properties in the building (Z) direction, while the properties in the X and Y directions showed minor differences across the three AFSD blocks. Furthermore, variations in tensile properties were observed depending on the sample orientation in the AFSD blocks and its depth-wise position in the part in the building direction. The microhardness values decreased non-linearly along the building direction, spread across the width of the part’s cross-section, and highlighted that the deposition layer thickness significantly affects this property. The 1 mm block exhibited lower average microhardness values than the 2 mm and 3 mm blocks. The temperature histories and dynamic heat treatment are influenced by the deposition layer thickness and depend on the location of the point being studied in the part, resulting in variations in the microstructure and mechanical properties along the building direction and across the part’s width.

Effect of process parameters on mechanical properties of PLA resin through LCD 3D printing

A widely existent method of fabricating 3D printed parts by polylactic acid (PLA) is by fused deposition modeling, which faces a poor surface finish when compared to resin-based 3D printing methods. The focus of the current work is to leverage LCD 3D printing to produce 3D printed PLA parts with improved strength and surface quality. Tensile, impact, and flexural specimens with varying layer thicknesses were printed and postcured to explore the mechanical properties. It was found that by increasing the layer thickness and minimizing the postcuring time, printed samples with maximum strength can be obtained. Further, rheological characterization was done to test whether the same resin is suitable for usage as raw material in direct ink write 3D printing and it was found that the resin with 4 wt. % and 5wt. % fumed silica were suitable for direct ink writing.