15 research outputs found
Effect of Additives on the Trap State Distribution of TiO<sub>2</sub>Anode in Dye-Sensitized Solar Cells
No full textSynthesis of Spinel-Hydroxyapatite Composite Utilizing Bovine Bone and Beverage Can
No full textSpinel-based hydroxyapatite composite (SHC) has been synthesized utilizing bovine bones as the source of the hydroxyapatite (HAp) and beverage cans as the aluminum (Al) source. The bovine bones were defatted and calcined in the air atmosphere to transform them into hydroxyapatite. The beverage cans were cut and milled to obtain fine Al powder and then sieved to obtain three different particle mesh size fractions: +100#, −140# + 170#, and −170#, or Al particle size of >150, 90–150, and <90 µm, respectively. The SHC was synthesized using the self-propagating intermediate-temperature synthesis (SIS) method at 900 °C for 2 h with (HAp:Al:Mg) ratio of (87:10:3 wt.%) and various compaction pressure of 100, 171, and 200 MPa. It was found that the mechanical properties of the SHC are influenced by the Al particle size and the compaction pressure. Smaller particle size produces the tendency of increasing the hardness and reducing the porosity of the composite. Meanwhile, increasing compaction pressure produces a reduction of the SHC porosity. The increase in the hardness is also observed by increasing the compaction pressure except for the smallest Al particle size (<90 µm), where the hardness instead becomes smaller
Key Deposition Parameters for Short-type ZnO Nanosheets Electrodeposited Under Galvanostatic Mode
No full textStudies on the deposition of ZnO nanosheets grown vertically and perpendicular to conductive substrates have been conducted to obtain tall-type nanosheets (approximately 15 µm in height). However, some applications require short-type nanosheets with a height of about 1µm or less. In this study, short-type ZnO nanosheets were electrodeposited on indium-doped tin oxide substrates under galvanostatic (constant current) mode for a short deposition time. Then, the key parameters to form nanosheet layers with a height in the micrometer order and with good coverage were evaluated. Deposition was performed at 1 mA/cm2 for 60 s. Ar gas was initially bubbled into the electrolyte solution during electrodeposition to remove oxygen. Then, the solution was compared with solutions that did not undergo bubbling. Various electrolyte compositions (various concentrations of acetate and nitrate) were observed in solutions under the non-Ar bubbling condition. Moreover, the oxygen in the solution remarkably affected the morphology of the nanosheet, which became much denser and taller. Therefore, altering electrolyte composition affects morphology, although the effect is not as significant. Electrolyte composition must be optimized to produce the desired short and dense nanosheets because a low concentration of each anion leads to the production of a non-nanosheet layer, whereas a high concentration causes reduction in the density coverage of the nanosheet. A complete discussion of this phenomenon is presented in this study
OPTIMIZATION OF MACHINING PARAMETERS ON THE SURFACE ROUGHNESS OF ALUMINUM IN CNC TURNING PROCESS USING TAGUCHI METHOD
No full textIn this research, Taguchi method is employed by focusing on spindle speed, feed rate, and depth of cut to optimize the CNC turning parameters for aluminum alloy 6063. The main goal of this study is to improve the surface roughness of the material. A L9 orthogonal array is used for experimentation, and the results are subsequently analyzed using ANOVA (Analysis of Variance). A spindle speed of 1300 rpm, a feed rate of 0.5 m/min, and a depth of cut of 1.5 mm are the optimal conditions to achieve the minimum average surface roughness (Ra). The main effect plot of the signal-to-noise (S/N) ratio provides significant evidence supporting the primary research goal. Furthermore, the ANOVA table reveals that spindle speed contributes 59.71%, feed rate contributes 29.80%, while depth of cut only contributes minimally at 0.72%. Based on the research findings, spindle speed and feed rate can be adjusted to control surface roughness. Both factors are highly significant in influencing the surface roughness of the material. The prediction equation from the linear regression analysis is Ra = 1.745 – 0.001024 spindle speed + 0.3000 feed rate – 0.0233 depth of cut. A coefficient of determination or R-squared value of 0.9115 indicates that the independent variables can explain 91.15% of the variation in the dependent variable. The experimental and predicted surface roughness (Ra) values have a predicted error percentage of 2.26%
Study of Eigenvalues and Matrix Eigenvectors Using MATLAB: Vibration Systems of Multi-Purpose Vehicle (MPV)
No full textVehicle vibration is a critical factor influencing both passenger comfort and vehicle performance. In this study, we analyze the multi-degree-of-freedom (MDOF) vibrational behavior of a multi-purpose vehicle (MPV) using matrix eigenvalue and eigenvector methods. The vehicle’s dynamics are modeled by developing a set of equations of motion that account for the forces acting on the front and rear tires, car body, and pitch angle. MATLAB is utilized to numerically compute the system’s eigenvalues and eigenvectors, representing the natural frequencies and vibration modes of the vehicle, respectively. The analysis focuses on the vehicle’s response to a 50 mm displacement at the front tire, simulating the effect of road disturbances. The resulting vibrations in the front and rear tires, car body, and vehicle pitch are illustrated over a 1-second time frame. The findings show that the front tire experiences the largest oscillation amplitude of ±1 mm, while the rear tire exhibits a much smaller displacement of ±0.04 mm. The overall car body displacement reaches a maximum amplitude of ±1.3 mm, indicating partial damping of the front tire vibrations. However, the results reveal that the vehicle’s suspension system lacks effective damping, as the vibrations do not decrease over time. This behavior could negatively impact ride comfort and safety, particularly on uneven roads. The study concludes that improvements to the vehicle’s suspension system are necessary to enhance damping performance. The presented MATLAB-based approach offers a valuable tool for analyzing and optimizing vehicle vibration systems
Mechanical Properties Analysis of Stainless Steel 304 Linear Guide Rail Using Autodesk Inventor and MATLAB
No full textThis study investigates the mechanical properties of a stainless steel 304 linear guide rail using a combination of Autodesk Inventor and MATLAB. The primary objective is to analyze the von Mises stress distribution, displacement, and safety factor of the linear guide rail under varying load conditions, as well as to develop a model representing the relationship between stress and strain. A detailed 3D model of the guide rail was created using Autodesk Inventor, followed by finite element analysis (FEA) to evaluate stress and strain distribution across different sections of the rail. The simulation was conducted to assess the structural response under multiple loading scenarios, ensuring its reliability for real-world applications. Furthermore, a linear regression analysis was performed using MATLAB to establish a predictive model correlating stress and strain, enabling more accurate forecasting of the material's mechanical behavior. The results revealed that the maximum von Mises stress obtained from the simulation was 23.595 MPa, with a corresponding maximum displacement of 0.397 mm. The safety factor analysis confirmed the rail's structural integrity, with a minimum safety factor of 10.595, well above the failure threshold. These findings indicate that the linear guide rail meets the necessary mechanical performance requirements for its intended application
Characteristics of Sodium Lithium Titanate Synthesized at Different Solid-State Reaction Temperature for Lithium-Ion Battery Anode
No full textThe effect of sintering temperature on the characteristics of sodium lithium titanate (NaLiTi3O7/NaLTO) synthesized at different solid-state reaction temperature and its performance as lithium-ion battery anode has been investigated. The precursors for the synthesis consisted of LiOH.H2O, TiO2, and NaHCO3. The synthesis was performed via solid-state reaction method. The precursors were mixed and sintered at variation temperatures of 900oC, 1000oC, and 1100oC for 2 hours under atmosphere condition. The final product was characterized using X-ray diffraction (XRD) and particle size analyzer (PSA). The XRD analysis showed the main phase of NaLTO with some impurities. PSA analysis showed that the sintering temperature has a significant effect on changes in particle size where the sample at a temperature of 1100oC has the largest particle size of 74.62 µm. The battery was fabricated by firstly mixing NaLTO powder with polyvinylidene fluoride (PVDF) and acetylene black (AB) in a ratio of 85:10:5 wt.% and the mix was then deposited onto copper foil to form NaLTO a sheet. The NaLTO sheet was cut into circular discs with a diameter of 14 mm and were arranged in a sequence of separator, metallic lithium, and electrolyte to form a coin cell in a glove box. Characterization using cyclic voltammetry (CV) and charge-discharge (CD) showed that the NaLTO sintered at 1000oC provided good electrochemical performance with the largest diffusion coefficient of 3.948 x 10-10 m2/s, Coulombic efficiency reached 100%, and a high specific capacity of 65.83 mAh/g
Recent Progress in Colloidal Quantum Dot Thermoelectrics
No full textSemiconducting colloidal quantum dots (CQDs) represent an emerging class of thermoelectric materials for use in a wide range of future applications. CQDs combine solution processability at low temperatures with the potential for upscalable manufacturing via printing techniques. Moreover, due to their low dimensionality, CQDs exhibit quantum confinement and a high density of grain boundaries, which can be independently exploited to tune the Seebeck coefficient and thermal conductivity, respectively. This unique combination of attractive attributes makes CQDs very promising for application in emerging thermoelectric generator (TEG) technologies operating near room temperature. Herein, recent progress in CQDs for application in emerging thin-film thermoelectrics is reviewed. First, the fundamental concepts of thermoelectricity in nanostructured materials are outlined, followed by an overview of the popular synthetic methods used to produce CQDs with controllable sizes and shapes. Recent strides in CQD-based thermoelectrics are then discussed with emphasis on their application in thin-film TEGs. Finally, the current challenges and future perspectives for further enhancing the performance of CQD-based thermoelectric materials for future applications are discussed
Sustainable Recovery of Fe(II) Oxalate from Steel Industry Waste Using Leaching, Hydrothermal, and Photo-Reduction Routes
No full textThe iron and steel industries have continuously expanded in recent years. These manufacturing companies are one of the main contributors to the environmental problems due to their by-products such as slag and mill scale. These solid wastes from iron and steel industries consist of a high iron element. Hence, the recovery of iron from these steel wastes can reduce secondary pollution and can have an economic benefit. Fe(II) oxalate is a critical building block material for several applications such as lithium-ion batteries, photocatalysts, pigment, etc. This work proposes a green synthesis technology with near-zero waste for the preparation of Fe(II) oxalate from steel waste in Indonesia. The following steps of leaching, photochemical reduction, and hydrothermal methods were used to achieve the purpose. The leaching process of steel waste using oxalic acid was conducted to produce a yellow precipitate of Fe(II) oxalate and the greenish filtrate (Fe(III) oxalate aqueous solution) as a by-product. The optimum dose of steel waste in oxalic acid solution was found at 50 mg/mL. Subsequently, photochemical reduction and hydrothermal were utilized to produce another Fe(II) oxalate from the greenish filtrate with high purity of Fe(II) oxalate in the form of α-FeC2O4⋅2H2O and β-FeC2O4⋅2H2O. A rod-like microstructure of Fe(II) oxalate was found in various sizes, depending on the synthesis route. A major particle length in the range of 4–10 μm was found for the leaching and photoreduction routes, while a larger size with a length of 150–350 μm was found for the hydrothermal one. Our results indicate that different methods influenced α or β crystalline structure as well as the particle size of Fe(II) oxalate
Electrical and Electrochemical Properties of Sandwich- and Monolithic-Structured Dye-Sensitized Solar Cells with Various Counter Electrode Materials
No full textA counter electrode is one of the crucial components in dye-sensitized solar cell (DSSC), where
platinum, carbon composite, and poly(3,4-dioxythiophene)-poly(styrene sulfonate) or PEDOT:PSS are
among the most widely used materials. In terms of configuration, DSSC is typically constructed in two
ways: sandwich and monolithic. However, the DSSC performance associated with the selection of both
counter electrodes and configuration has received little attention to date. This study aims to study the
effect of counter electrode materials on DSSC performance by analyzing their electrical and
electrochemical properties from their configuration standpoint. First, the physical properties of the
counter electrodes materials were analyzed using scanning electron microscopy (SEM), followed by
four-point probes, electrochemical impedance spectroscopy (EIS), incident photon-to-current
conversion efficiency (IPCE), and current density-voltage (J-V) characterization. Among all variations,
our results show that the sandwich-type DSSC with PEDOT: PSS counter electrode generated the best
performance with a power conversion efficiency of 5.40%, which was primarily attributed to the high
conductivity (3210 S/cm) and low charge transfer resistance (RCE 53 Ω). It was also found that the
electron transfer pathways that are determined by the cell configuration also had a significant impact on
the cell performance
