Power-to-gas systems with a focus on biological methanation

Seongcheol Kang,Anil Kuruvilla Mathew,Amith Abraham,Okkyoung Choi,Byoung-In Sang 한양대학교 청정에너지연구소 2022 Journal of Ceramic Processing Research Vol.23 No.6

Power to Gas (P2G) systems aim to store surplus renewable electricity generated in the form of gaseous fuels such as hydrogenor methane. The concept is ideal for storing the surplus energy for long periods in gaseous form and can be used in the futurefor desired end applications, i.e. either in gaseous form or electricity. In the P2G process, the surplus renewable energyconverts into methane (gaseous form) in a two-step process: electrolysis followed by methanation. The electrolysis process isused as the source for hydrogen generation, which further reduces carbon dioxide to produce methane. In this review, differentelectrolyzers and methanation processes are compared for the P2G process. The major process parameters and hydrogen gasliquid mass transfer are discussed by comparing different process conditions and reactor configurations used in biologicalmethanation. An understanding of the techno-economic analysis indicates that cost of the hydrogen generation is the key factorthat determines the overall economics of the P2G system. The cost of hydrogen generation is associated with the capital costof the electrolyzer and the cost of the electricity. It is expected that once this technology becomes mature, the economics of P2Gsystems will improve in the future.

Enhancing micromachining precision with novel electrolyte combinations: an investigation

Sudharsan Gunasekaran,Suresh Periyagounder,Magibalan Subramaniam 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.4

Electrochemical micromachining is a non-traditional machining process used for drilling at the micro level. The process ischallenging to control due to its reliance on reaction parameters like over-cut, material removal rate, and taper. The removalrate of material (MRR) and overcut are key responses observed during the process. Recent studies have focused oninvestigating the effect of process parameters such as Electrolyte concentration, voltage, and duty cycle on electrochemicalmicromachining. Researchers have found that variations in the Electrolyte type, combination, and duty cycle can significantlyimpact material removal rate and overcut. In this work, the combination of novel electrolyte and the optimal temperature wasmaintained to carry out the experiments. The removal rate of material and overcut are critical responses observed during theprocess in which electrolyte concentration has shown to impact these responses significantly. SEM (Scanning ElectronMicroscope) images have been used to analyze the resulting drill surfaces, providing valuable insights into the microstructureand morphology of the drilled holes.

Use of geopolymer-derived leucite as a reinforcement in dental bioceramic composites

Cengiz Bagci 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.4

Leucite (K2O·Al2O3·4SiO2) converted from geopolymers as a sustainable approach, was used as an alternative to feldspar, oneof the three components of dental ceramics. Leucite crystals were obtained from a dried potassium geopolymer of thecomposition K2O·Al2O3·4SiO2·11H2O by heating at 1200 oC for 3 h in an open-air furnace. Produced leucite was crushed intosmall parts, powdered in a planetary mill and then sieved to sub-63 micron size. Leucite crystals were then replaced byfeldspars at a range from 0-100 (wt.%) in all three parts of dental ceramic slurries. The slurries were molded to 1 cm3 andsubsequently heat-treated at 1300 oC-1450 ºC/4.5 h with a heating rate of 10 ºC/min. Final products were microstructurallycharacterized with XRD, SEM-EDS and mechanically based on Weibull analysis of compressive tests. Due to the phasetransformation occurring in leucite, it was determined that the amount of leucite had a significant effect on the structuralintegrity and therefore the mechanical properties of the final dental material. Results of the statistical analysis showed that thereplacement of 50% leucite exhibited the highest compressive strength of (49.3±10.5 MPa) compared to the other samplesconsistent with microstructural analysis.

Performance of expanded clay aggregate based structural light weight concrete beams containing fibre reinforcement

K.K. Gaayathri,K. Suguna,N. Raghunath Pulipaka 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.4

The current work examines the flexural behavioral analysis of structural lightweight concrete (SLWC) beams made ofexpanded clay aggregate (ECA) and its conclusions. Polypropylene (PP) fiber is used in these beams. The investigation tookinto account a total of six beams, of which one specimen was constructed using regular-weight concrete and the other usingSLWC with 20% ECA in place of coarse aggregate. The remaining four beams were constructed using SLWC material withan ECA base that included polypropylene fiber in volume fractions of 0.1%, 0.2%, 0.3%, and 0.4%. Each beam underwenttesting in a loading frame up to 4-point bending.

Regulation of BaTiO3 ceramics’ electrical properties by varying Na0.5Bi0.5TiO3 dopants

Shuiyun Li,Mingyang Ma,Yongshang Tian,Ruobing Li,Xiongjie Hu,Peng Liu 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.4

The piezoelectricity of BaTiO3 (BT) ceramics could be effectively regulated by Na0.5Bi0.5TiO3 (NBT) compounds, and themechanism is still controversial. In this work, BT-xNBT ceramics with various NBT contents (x) were synthesized by aconventional solid-state sintering process. The characteristic of phase, cross-section morphology, permittivity, ferroelectricity,and piezoelectricity were fully explored by some advanced test equipment. With an increment of x, the ceramics possessed ahigh densification with a sole tetragonal phase, the diffused phase transition and relaxor ferroelectricity enhanced firstly andthen receded. The inherent ferroelectricity and large strain of NBT materials under an electric field were deemed as thereasons for the increased ferroelectricity and piezoelectric coefficients with excessive x, respectively. Moreover, influences ofimpurity phases, fine grains, internal stress, etc. on the electrical properties were also discussed. This work provides a novelstrategy to regulate BT-based lead-free piezoelectric ceramics.

Optimization of fiber length and filler content for improving the mechanical behaviour of musa acuminate fiber-reinforced epoxy composite using response surface methodology

S. Sathiyamurthy,S. Saravanakumar,N. Ananthi,P. Devi 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.4

In recent years, it is crucial to describe and enhance the natural fiber’s strength qualities as well as look for new opportunitiesto use them in composite materials. The technical characteristics of a novel series of Al2O3 and Boiled eggshell fillers addedpolymer composite using Banana fiber as a strengthening material in an Epoxy polymer matrix have been studied in thiscurrent experiment. Composites were created and evaluated for varying fiber lengths (100, 150, and 200 mm) and weightpercentages of fillers (5, 10, and 15%). 9 samples were prepared and the tensile (TES), flexural (FLS), and impact strength(IMS) of the composites were measured. The numerical formulas were developed for the tensile strength, flexural strength, andimpact strength with the investigated process factors using the Design Expert 13 statistical software output coefficients. Optimization was carried out using response surface methodology and the ultimate ideal parameters for maximum tensilestrength, impact strength, and flexural strength were discovered as a fiber length of 200 mm and filler content of 11.74%. Finaloptimum values were found the tensile strength of 14.25 MPa, the impact strength of 37.71 kJm-2, and the flexural strengthof 36.069 MPa. It is observed that the impact of Al2O3 and boiled eggshell filling materials in the improvement of mechanicalproperties are very enormous.

Coating of Si3N4 with HAp via atomic layer deposition

Seniz R. Kushan Akin 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.4

Silicon nitride (Si3N4) is an attractive implant material, particularly in orthopedic surgery. Although it has only been on themarket for spinal fusion surgery requirements so far, it is also a promising candidate for other implant applications whereload-bearing is crucial. In this study, we aimed to examine the potential of making the material surface more advantageousfor various implant applications by coating it with a very thin hydroxyapatite (HAp) layer using the atomic layer deposition(ALD) method. This was done to improve the material's bioactivity without sacrificing its mechanical properties. Characterization results showed that using a 3:1 CaO:PO4 ALD cycle ratio resulted in the formation of very fine crystallineHAp after heat treatment at 500 °C. The bioactivity assessment made by immersing the coated film in SBF revealed HApformation on the surface, and it was observed that the bioactivity of this surface improved compared to the uncoated one.

Effect of heat treatment on microstructure and tensile strength of KD-II SiC fibers in argon and oxidation atmosphere

Huan Yin,Fenghao Yang,Guangmin Hu,Maozhong Yi 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.4

The polycarbosilane derived KD-II SiC fibers were heat treated in argon atmosphere at temperatures from 1000 °C to 1800°C and in oxidation atmosphere at temperatures from 1000 °C to 1500 °C for 1 hour, respectively. The effect of heat treatmenton microstructure of all fibers were characterized by X-ray diffraction, scanning electron microscopy, transmission electronmicroscopy, X-ray photoelectron spectroscopy and Atomic Force Microscopeand, and the tensile strength of fibers wereevaluated by monofilament tensile test and Weibull model. The results reveal that the fibers of heat treatment in argonatmosphere can maintain their original tensile strength (~2.5 GPa) up to the temperature at 1200 °C. After that, their tensilestrength starts to decline, especially when the temperature exceeds 1400 °C a sharp strength degradation is observed. Throughdetailed characterization, we find that the reasons for the strength degradation of fibers heat treatment in argon atmosphereinclude the appearance of surface defects, growth of β-SiC grains and decomposition of SiCxOy amorphous phase. Correspondingly, the fibers heat treated in oxidation atmosphere have lower tensile strength compared with those fibers heattreatment in argon atmosphere at the same temperature. Furthermore, their tensile strength starts to degenerate at 1000 °C,and only 30% of original strength is retained when the temperature reached 1500 °C. Obviously, for fibers heat treatment inoxidation atmosphere, their tensile strength degradation starting temperature is lower and degradation speed is faster thanthose fibers heat treatment in argon atmosphere. This can be attributed to the interface stress existed between silica layer withinternal fibers, the surface cracks caused by the thermal stress and the growth of β-SiC grains.

Effect of La2O3 on the microstructure and electrical properties of ZnO linear resistors

Yajun Fu,Jiajia Lu,Jin Wang,Liangfeng Li 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.4

ZnO-MgO-Al2O3-TiO2-Y2O3 linear resistors with different amount of La2O3 were successfully prepared by the conventionalsolid-state sintering method. The crystalline phase composition, microstructure, and electrical properties of La2O3 doped ZnOlinear resistors were investigated. The results show that La2O3 influences the lattice of ZnO and generates La-rich phase atthe grain boundaries, which improves the dense density of ZnO linear resistors. The addition of La2O3 further affect theelectrical properties of ZnO linear resistors, such as the temperature stability. The sample with 0.5 wt.% La2O3 show excellentelectrical performance with an resistance-temperature coefficient of 0.21×10-3/°C and an nonlinear coefficient of 1.05.

The phase simulation of High-Tc superconductor compound YBa2Cu3-yPbyO6.5+δ

Emad K. Al-Shakarchi,Salwan K.J. Al-Ani,Wedad M. Faysal 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.4

The simulation of a possible change in a structural phase of superconducting compound YBa2Cu3-yPbyO6.5+δ was done for thesamples prepared by solid-state reaction represented by (y=0-0.5). Theoretically, the probability structural phase was derivedfrom a pure structure YBa2Cu3O6.5+δ, which had an orthorhombic phase with lattice constants (a=3.8203, b=3.8855, and c=11.6835 Å) and space group Pmmm. There is a partial variation in the orthorhombic unit cell from the pure phase throughthe substitution of Pb. There is a structural phase transition from orthorhombic to tetragonal phase at (y=0.2, 0.3). The limitedvariation in the lattice constant is around the theoretical values with the orthorhombic phase. The valency (+2) of Pb-ions tookplace in the position of Cu+2-ion in the composition YBa2Cu3-yPbyO6.5+δ. There is a sharp increase in the lattice constants (b,c) at y=0.4 with the remaining orthorhombic phase and space group Pmmm. The simulation exhibited the position of atomswithin the unit cell, which was a function of the bond's nature between different atoms and their effect on the conductivitybehavior with Pb substitution. The results predicted a linear relation between the c-axis and oxygen excess (δ).