Materials Science Forum Vol. 1144

Abstract: This work analyzes the lattice, electronic structures and hole concentration of calcium-doped YBCO compounds using density functional theory. The investigation was conducted on two models, Y_0.875Ca_0.125Ba₂Cu₃O₇ (YCa123) and Y_0.875Ca_0.125Ba₂Cu₄O₈ (YCa124), using density functional theory. The results reveal that calcium substitution induces changes in the lattice structure, including a decrease in the lattice constant and a distortion of the Cu-O₂ plane. Furthermore, the electronic structure was also altered, leading to changes in the density of states above the Fermi level. The hole concentrations were also calculated and were found to be 0.19 and 0.16 for YCa123 and YCa124, respectively. These results indicate that the hole concentration of YCa124 is lower than that of YCa123, consistent with the parabolic curve relationship between hole concentration and superconducting transition temperature. The results suggest that Cu (2) atoms fluctuate between the states of Cu⁺ and Cu²⁺, which may be crucial for understanding electron-electron pairing mechanism. These results could aid in the development of more efficient and practical superconducting materials through targeted doping strategies.

Abstract: This research presented the preparation as well as characterization of high and low density Bi (Pb)-2223 cuprates superconductors doped with Eu₂O₃ nanoparticles (x = 0.00, 0.0025, 0.02 and 0.05) produced through a typical solid state reaction method. Low density sample was created by adding crystalline sucrose into mixed powders and burned at 400 °C for two hours. The crystalline structure was analyzed through X-ray diffraction (XRD) while electrical properties were studied using four-point probe measurement. Phase examination by XRD revealed that the crystallographic structure has shifted slightly from tetragonal to orthorhombic at higher Eu concentrations for both high and low density samples. The amount of 2223 phase steadily decreased as the Eu concentration increased, indicating that the substitution of Eu nanoparticles favours the formation of 2212 phases. Apparently, the T_c value of the high density Eu-free sample was determined at 89 K. The addition of polycrystalline sucrose as a filler raises the T_c up to 99 K in low density sample. However, increasing amount of Eu nanoparticles leads to the decrease in T_c value. Meanwhile, the J_c value is higher in low-density samples compared to high-density samples due to the presence of large surface area in a porous structure which enhances the grains connectivity. The best structural and electrical properties between the studied samples have been observed at sample with x = 0.0025 for both high and low density Eu-doped Bi (Pb)-2223.

Abstract: An artificial algorithm using a machine learning approach could be used to determine the energy band gap, E_g which would simply the process of synthesizing ZnO properties. This paper proposes to develop machine learning models that can accurately predict the energy band gap of ZnO. This study used PSO-SVR model utilizing three kernel functions: linear, polynomial, and RBF. The PSO-SVR with RBF resulted in the lowest RMSE of 0.0395eV. This analysis also showed that the combination of lattice constant a and c, crystallite size, D and grain size of ZnO datasets had contributed to high accuracy of predicting E_g.

Abstract: Adsorption-based separation technology has emerged as a promising method for capturing carbon dioxide (CO₂) from natural gas. The application of ultrasonic-aided pretreatment prior to hydrothermal heating appears to be a viable alternative in promoting rapid synthesis for porous structures. In the present research, Gismondine (GIS) zeolite were synthesized via ultrasonic-aided hydrothermal growth method to reduce the formation duration of zeolite. The ultrasonic-aided pretreatment period were varied from 30 min to 90 min and hydrothermal growth durations were manipulated from 1 day to 5 days. The resulting GIS zeolites were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). As verified by XRD, SEM and FTIR, the samples synthesized via ultrasonic-aided pretreatment of 60 min and 90 min exhibited GIS zeolite crystal structure. Furthermore, the application of ultrasonic-aided pretreatment has successfully accelerated the formation of GIS zeolite to 2 days as compared to 7 days required by the conventional hydrothermal growth method.

Abstract: This study analyzes the wear mechanisms of a Kevlar-Zirconia-Epoxy composite casing coating under varying drillpipe joint speeds and side loads, using both dry and water-based mud lubrications. Employing Scanning Electron Microscopy, the research highlights the influence of ceramic microfillers on the wear characteristics. Findings indicate that abrasive wear dominates at low speeds, while higher speeds increase adhesive wear. Side load changes had minimal impact on wear mechanisms. Additionally, specimen temperature significantly affects composite behavior, underscoring the importance of lubrication for maintaining composite integrity. The results suggest this composite is well-suited for applications requiring high durability and wear resistance.

Abstract: PMMA resin has been commonly used for fabricating surgical obturators. However, the surface roughness and porosity of the resin can cause microbial aggregation and biofilm formation, leading to potential complications for the patients. Recent progress in antimicrobial strategies for PMMA resin has been reported. It was shown that incorporating vanillin into PMMA resin inhibited biofilm formation by bacteria and yeasts. However, the effect on other properties of the resin has not been studied. The aim of this study was to evaluate the mechanical properties of PMMA resin with 0.1% and 0.5% vanillin incorporation, including flexural strength, flexural modulus, and surface hardness, compared to a control group. All tests were performed according to ISO 20795-2:2013. For flexural strength and modulus, specimens are tested using a three-point bending machine. A Vickers hardness apparatus was used for the surface hardness test. Data on both surface hardness and flexural modulus were statistically analyzed by one-way ANOVA and Turkey’s multiple comparison test. Those of flexural strength were statistically analyzed by the Welch and Dunnett T3 Test with a significance level of 0.05. Results indicated that increasing the amount of vanillin incorporation decreased flexural strength, modulus, and surface hardness. Nevertheless, flexural strength and modulus were still within ISO standards. In conclusion, the incorporation of vanillin into PMMA resin could affect its mechanical properties. However, the application of this resin in a clinical setting could possibly be done due to its standardized flexural strength and modulus.

Abstract: This study addresses the reinforcement of corroded API 5L X42 pipelines using Glass Fiber Reinforced Polymer (GFRP) composite wraps, focusing on optimizing fiber orientation to enhance burst pressure performance. Pipeline corrosion poses significant risks to structural integrity and safety in the oil and gas industry. Experimental burst pressure testing, and Finite Element Method (FEM) were conducted to evaluate unidirectional (0/0/0), bidirectional (0/90/0) and multi-axial (0/45/-45) GFRP wraps. The FEM model, validated against experimental data, showed minimal error with 1.16%. Major findings show that the bidirectional had a maximum stress (501.29 MPa) and burst pressure (44.72 MPa) higher than the unidirectional and multi-axial. Better stress distribution given by the bidirectional structure helped to lower stress concentrations. These results show that pipeline repair techniques can be much improved by orienting fibers correctly. This study found that it helpful in field application of composite repair techniques for corroded subsea pipes.

Abstract: Radiative cooling (RC) technology is becoming crucial with several prospective applications, either as a standalone or in conjunction with conventional cooling systems. The RC flux can be enhanced by tailoring selective spectral emissivity and suitable surface orientation (i.e., azimuth and tilting orientation). However, it has not been studied extensively from the perspective of emissivity modification in the composite layers. Polymer and ceramic particle composite’s emissivity (i.e. selective wavelength dependent spectrum) is based on the effective refractive index estimation. In this article we estimate the effective refractive index of the composite structures using Mie theory and the layer transmissivity approach. In the Mie theory, forward scattering from a composite sphere is monitored with respect to background refractive index. In the layer transmissivity approach, refractive index of composite is estimated from the transmission spectrum (i.e. Fresnel equations) of number of layers with different thickness. The refractive index from these two approaches is in the close agreement at large wavelengths (non-dimensional size parameter x=2πr/λ is below 1). However, the layer transmissivity approach yields a higher effective refractive index for the wavelength comparable to particle size (x =>1) inclusions with lots of fluctuations. The effective refractive index estimation aids in the designs of distributed Bragg stack and quasi-amorphous structure. The selective emissivity within the solar spectrum is also expected from quasi-amorphous structures of these existing polymer and ceramic particles composites. The potential applications of these findings are synthesis of coatings for radiative cooling of residential buildings and solar PV panel. Additionally, implementation of these coatings based radiative cooling phenomena would be very effective in terms of reduction of global warming and heat island effect.

Abstract: Annually, billions of metric tonnes of solid waste are produced, including Polyethylene Terephthalate (PET) plastic waste and other industrial manufacturing by-products. This study assesses durability of waste plastic bricks (WPB), which are made by repurposing scrap plastics from PET. Mechanical and fire resistance properties of WPB have been optimised by varying mixing proportions of PET plastic and mixtures of industrial waste materials like fly ash, waste glass powder and concrete debris in ratios of (20:80, 30:70 and 40:60) respectively. This investigation integrates various wastes synergistically to produce bricks, aiming to replace traditional bricks made from cement and clay. This study investigates mechanical and physical properties of interlocking blocks made from mixtures of plastic and industrial waste materials, including fly ash, waste glass powder, and concrete debris. A mixture ratio of 20:80 (plastic to waste materials) yields a compressive strength of 27.3 N/mm², suitable for use in partition walls. Water absorption rates decrease significantly from 3.5% in conventional blocks to 0.5% in 20:80 ratio blocks, with further reductions to 0.43% and 0.40% for 30:70 and 40:60 ratios, respectively, enhancing water resistance. Efflorescence tests indicate improved performance in blocks with higher proportions of alternative materials, meeting highest standards for first-class bricks. Fire resistance tests confirm that all block compositions, including conventional and mixed ratio blocks, achieve a one-hour fire resistance duration, compliant with ASTM E119 standards, ensuring durability and safety of these alternative material blocks.