Solid State Phenomena Vol. 349

Abstract: Standard duplex stainless steel X2CrNiMoN22-5-3 is resistant to both, corrosion and mechanical stress, but corrosion fatigue (CF) lowers the lifetime expectancy in a geothermal environment such as the Northern German Basin. Laboratory experiments used the in-situ electrolyte at 369 K in a specifically designed corrosion chamber applying rotation bending cyclic load to failure. CF behaviour was compared to pure push-pull load. Corrosion kinetics are independent of the load applied. Failure is initiated by pits resulting in mechanical degradation. Increased thickness of the passivating layer surrounding pits enhances degradation or delamination. Also, sharp notches located along the pit edge increase notch effects and stress concentration consequently leading to fast crack propagation and early failure.

Abstract: Aluminum-based alloys, due to their high properties compared to pure aluminum, have expanded their use in building the aircraft strength structures, in the automotive construction and in the naval field. Some of these, such as the radome (aircraft nose) and the wings of the airplane, are exposed also to intense stress from the erosion created by the impact with the raindrops. The literature considers this type of damage to be assimilated by the erosion trough cavitation. Therefore, the paper presents the results of the behavior and resistance to erosion trough vibratory cavitation of the 7075 - T651 aluminum alloy structure, heat treated by artificial aging at 140 °C for 12 hours. The research has been carried out on a standard device that complies with the requirements described in ASTM G32-2016. The structure strength obtained through the researched heat treatment, is evaluated through comparison with the state obtained by artificial aging at 180 °C with a similar duration of 12 hours. The evaluation is done by comparing the parameters recommended by the ASTM G32-2016 norms of the two heat treatments. The results show that the achieved gain is slightly increased.

Abstract: The melt jet spinning process has been used for production of consistently fine nonwoven fibers. The process was applied to produce the biodegradable nonwoven fabric such as poly (lactic acid) (PLA). However, the rigid nonwoven PLA fibers limited the application of nonwoven. To improve the nonwoven fiber flexibility, the fabrication of PLA/PBS blend nonwoven fabric using melt jet spinning process under various process conditions was studied. In the melt jet spinning process, the nozzle temperature is varied between 250 to 280 °C. The performance metric evaluation is comprised of fiber diameter, fiber crystallinity, mechanical property and contact angle. The fiber diameter, crystallinity and tensile strength of PLA/PBS blend nonwoven fabric decreased with increasing nozzle temperature. The optimum process condition of the PLA/PBS nonwoven fabric production was found at nozzle temperature of 280 °C to produce the nonwoven fiber with average diameter of 5.1 μm. The forming temperature has no effect on the hydrophilic properties of PLA/PBS nonwoven fabric. The melt jet spinning process was successfully applied for the biodegradable polymer to produce the environmentally friendly products.

Abstract: In order to improve the conformity of the glove wearers, the microporous breathable polyethylene gloves are developed using Low-Density Polyethylene (LDPE), Ziegler-Natta Linear-Low Density Polyethylene (ZNLLDPE), Metallocene Linear-Low Density Polyethylene (MLLDPE) and calcium carbonate filler (CC). In this study, LDPE/ZNLLDPE/CC and LDPE/MLLDPE/CC microporous films were prepared to investigate the influence of ZNLLDPE and MLLDPE on the film breathability and elongation. The microporous films were characterized by Scanning Electron Microscope (SEM) analysis, X-ray Diffraction (XRD) analysis and Particulate Filtration Efficiency (PFE) analysis, Water Vapor Transmission Rate (WVTR) testing and mechanical properties testing. Based on the result, LDPE-MLLDPE film yielded film breathability of 335.73 g/m² ∙ day which is 95.3% higher than LDPE-ZNLLDPE film due to the higher LDPE-MLLDPE film crystallinity and prominent dewetting behaviour between CC and LDPE/MLLDPE matrix. Moreover, the high degree of tie molecules in MLLDPE enabled the film to stretch further upon film elongation. Therefore, LDPE-MLLDPE film showed up to 207.2% comparatively better film elongation than LDPE-ZNLLDPE film. The improved film breathability and film elongation render the mixture of LDPE/MLLDPE/CC as a better material for breathable polyethylene glove production.

Abstract: The research on the synthesis of nanoparticles using the high-energy ball milling method technique is limited in Indonesia. This work aims to reduce the size of the remaining biochar powder from the lignocellulosic residual forest (twig) into a nanoparticle. High-Energy Ball Milling-Ellipse 3 Dimension (HEM-E3D) was used to grind the biochar through 212 um mesh with time variations of 0, 2, 3, and 4 hours. The speed of the HEM-E3D is 180 rpm, while the milling on and off times are 10 minutes and 1 minute, respectively. The Particle Size Analyzer (PSA) characterization data show that 4 hours is the optimal milling time with 282,7 nm and evenly distributed particles. The morphology of powder biochar resemblant sheets and an average size of 205 nm at 60000x magnification. There were no discernible and damaged functional group alterations in the surface functional groups as determined by Fourier Transform Infrared Spectroscopy (FTIR). The adsorption experiment using a thin film method shows that powder biochar could reduce heavy metal concentrations of Cr (VI).

Abstract: A pulverized-coal boiler is a type of boiler that is commonly seen in power plants. During an operation, a portion of the coal is converted to ash. The consequence is a cause of slagging on the furnace wall and a considerable loss in heat transfer performance. In coal-fired power plants, slagging is one of the most common causes of maintenance issues. This problem can be resolved by using a water soot blower cleaning system. It shoots a high-pressure jet of water through a hole in the side of the furnace’s wall to clean the opposite wall surfaces. This study presents a Computational Fluid Dynamics (CFD) investigation of the water soot blower trajectory with a flow field in full-scale boiler. Multiphase-flow simulation is utilized. The turbulence model couple and Discrete Phase Model are used to analyze flow field in boiler and water soot blower trajectory, respectively. The aim is to accurately determine an injection angle degree for the water soot blower. The CFD results are compared with the experiment of water soot blower shooting in Cold Air Velocity Test (CAVT) conditions. The results of the study show that the simulation results agree with the experimental data. Moreover, the velocity profile of numerical study shows that the effect of flow field in boiler has little effect on the water soot blower trajectory.

Abstract: This study focus is on the physical solvent-based CO₂ capture process from an integrated Gasification Combined Cycle (IGCC) power plant, followed by a comparison of Dimethyl ether of polyethylene glycol (DEPG) solvent and methanol solvent, which is based on traditional technology and has a 95% CO₂ purification requirement. After achieving the optimal condition, we would compare which solvents are suitable for this system. This procedure was simulated in Aspen HYSYS. Additionally, this study examined the effects of factors that provide the CO₂ capture cost per ton ($/tCO₂ captured). The response surface approach is used to get the optimal result. In the case of the optimal condition of DEPG solvent, the inlet temperature of fuel gas is – 2 °C, the stripper of inlet temperature is at 67 °C, the pressure of the absorber is at 2,994 kPa, and the stage of absorber appears to be 12 stages. As a result, the lowest DEPG solvent process cost is $189.63 per ton of CO₂ collected. The minimum cost of CO₂ capture under the optimal condition of methanol solvent, where the temperature of the absorbent and fuel gas is – 8 and – 20 °C, the stripper inlet temperature appears to be at – 6 °C, and the concentration of the absorbent is 88.85 wt.% in methanol solvent, is then $19.21 per ton of CO₂ captured.

Abstract: The Langevin theory of diamagnetism is used to examine the effects of geometric confinement and hydrogenic impurity location on the diamagnetic susceptibility in a GaAs hemispherical quantum dot with an infinite confinement potential considered as vacuum. Using the finite difference approach and the effective mass approximation, the electron-donor Schrödinger equations are derived. As a function of the size of the hemi-spherical quantum dot, the mean value of the electron location and electron to ionized donor atom distance are investigated, taking into account the various impurity positions. The results show that shrinking the size of the hemi-spherical quantum dot improves the diamagnetic susceptibility by reducing the electron-donor distance. The major findings show that the donor impurity location has a significant impact on the diamagnetic susceptibility. We believe that the findings from our work into the diamagnetic susceptibility of quantum dots will be crucial in determining how well optoelectronic devices will operate.

Abstract: In this work, we have studied an electron confined in a GaAs Horn torus quantum dot in the presence of a shallow donor impurity. Using the effective mass approximation and by considering an infinite confinement potential, the Schrödinger equation was calculated by the finite difference method. The electron-impurity binding energy and the diamagnetic susceptibility are studied for different geometric sizes of the Horn torus. In addition, the effect of the radial and angular positions of the shallow donor impurity on the binding energy and the diamagnetic susceptibility are examined. The results show that the binding energy is much higher at small sizes of the nano system. Also, the diamagnetic susceptibility exhibits a symmetric behavior as a function of the angular position of the shallow impurity donor unlike that when the impurity moves radially. The influences of these parameter variants help us to better understand the effects of the size of the quantum dot and the position of the donor impurity, which improve the sensitive of the opto-electronic devices.