Materials Science Forum Vol. 975

Abstract: Study of TiC interaction with low-and high-carbon steel is presented in this article. Was carried out interaction thermodynamic modeling in the temperature range of 900-1800 °C, which showed that titanium carbide would dissolve in melts with these compositions, regardless of melt’s carbon content at given parameters. The obtained thermodynamic results were verified by conducting an experiment with high-temperature complex in order to study substances interaction processes. The obtained experimental samples were studied with scanning microscope as well as structure and compounds composition, obtained as a result of experiment mentioned above.

Abstract: PES is used as raw material for the preparation of membrane in this paper. Through gas-assisted-phase separation and synergetic pore-forming technology, the influence of the content of CaCO₃ in foaming pore-forming agent and the content of N,N-DMAc in coagulation bath on membrane property is studied. The results indicate that this method prepares PES hollow fiber membrane with uniform macroporous structure in which the cross section is wedge-shaped and running through internal and external surface. The addition of CaCO₃ can improve membrane property and the increase in the content of DMAc also has a great positive influence on membrane property.

Abstract: Carbonated hydroxyapatite (CHAp) is an inorganic mineral that more closely resembles the main component of composing human hard tissue in 2-8 wt% carbonate content. CHAp powders have been synthesized from oyster shells using the precipitation method. Oyster shells are one type of shellfish from the bivalve class which is rich in calcium carbonate content. In this research, CaO from oyster shells obtained from the decomposition process of CaCO₃ was used as a source of calcium and diammonium hydrogen phosphate and ammonium bicarbonate as well as a precursor of phosphate and carbonate, respectively. In addition, carbonate content variations were x = 0, 0.3, 0.8 and 1.2 which were characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), and scanning electron microscope-energy dispersive X-Ray (SEM-EDX) to determine the functional groups, crystallographic properties, morphology and Ca/P molar ratio, respectively. Carbonate ion substitution in the hydroxyapatite crystal structure is known to decrease crystallinity and crystallite size. The theory is in accordance with the results obtained in this study with the crystallite size is 74.322, 46.933, 37.727, and 31.499 nm for 0.95, 2.7, 5.7, and 9.35 wt.% carbonate content, respectively.

Abstract: The aim of this work is to investigate the influence of sintering temperature on purity and crystallography properties of carbonated hydroxyapatite (CHAp). The CHAp was synthesized using a coprecipitation method. The snail shells (Pilla ampulacea) were processed to yield calcium oxide as the calcium source in synthesis. The CHAp powder then was sintered for 2 h in an air atmosphere at 400, 600, 800, and 1000°C. An X-Ray diffractometer (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and energy dispersive x-ray (EDX) are used to investigate the physicochemical properties of CHAp. XRD, FTIR, and EDS results show primary phase is carbonated hydroxyapatite. Calcium oxide as a secondary phase is detected starting from 800°C. The crystallinity and crystallite size are increased along the increasing of sintering temperature. Drastic enhancement on these properties is shown at 600–800°C. However, there is no simple relation to the sintering temperature and lattice parameters. These results show that sintering temperature has an important role in the purity and crystallography properties of the CHAp.

Abstract: In this study, the effects of curing white Portland cement (WPC) and hydroxyapatite mixed with white Portland cement (HAp/WPC) pastes in water and the in vitro biological environment on the compressive strength and bone-like apatite formation were examined. The compressive strength of both WPC and HAp/WPC pastes increased with longer curing periods in water. The compressive strength of WPC and HAp/WPC pastes was 51.88 and 25.67 MPa, respectively, after curing in water for 28 days. The compressive strength of both samples continuously increased during in vitro testing in a simulated body fluid (SBF). After 4 weeks of immersion in a SBF, the strengths of cured WPC and HAp/WPC samples were 59.01 and 28.06 MPa, respectively. It is due to continued hydration of WPC. The addition of HAp to WPC decreased the compressive strength of the sample. Alternatively, it enhanced bone-like apatite formation on the surface of the samples.

Abstract: Metalworking fluids (MWFs) are widely used in the metal forming industrials. It was used for reducing of the friction and cooling of the mechanical processes. In this research, the modified sugarcane bagasse (MSB) with aluminium sulphate (Al₂(SO₄)₃) was used as an adsorbent for removal of the metalworking fluid in Continuous Stirred Tank Reactor (CSTR). The point of zero charge of sugarcane bagasse and modified sugarcane bagasse were pH 6.1 and 3.7, respectively. The effect of initial concentration of metalworking fluid was studied. When used the reactor 3 L and flow rate at 0.055 L/min, the % removals of MWF at initial concentration 6,480-41,513 g/m³ were 98.0-56.7%, respectively. The significant uptake of metalworking fluid was demonstrated by FT-IR spectroscopy.

Abstract: In this paper, a novel local surface nanocrystallization treatment is introduced to design the anti-buckling rectangular plate. The mechanical properties and critical buckling loads of the plates are greatly improved by the surface nanocrystallization technology. Several local nanocrystallization layouts, including the horizonal stripes distribution, the vertical stripes distribution and the spaced latticed blocks distribution, are designed and numerical simulations are carried out to evaluate the stability of the plates. Results show that the critical buckling load was significantly improved by the local nanocrystallization treatment. Among all the designs, the critical buckling loads for the vertical nanocrystallization layouts is the optimal one. And the technology can also be extended to the anti-buckling design of other structures.

Abstract: A novel rectangular tube with circumferential anti-symmetric local self-surface nanocrystallization (CALSSN) layouts is designed for energy absorption. The effects of stripe numbers on the energy absorption performance is investigated. Results reveal that the 8-stripe CALSSN model exhibits the best buckling modes, which is more regular and stable than the untreated ones. It is also found that the stripe numbers highly depend on the structural sizes, unsuitable stripes number may reduce the buckling stability and periodicity. Besides, five CALSSN models with stripe numbers from 6 to 10 are selected to find the optimized size which has the highest specific energy absorption (SEA). A new 7-stripe CALSSN model which has optimal buckling modes and energy absorption performance is achieved.

Abstract: This work presented the high activity of metal-free g-C₃N₄ photocatalyst for methylene blue (MB) removing over natural sunlight irradiation. These g-C₃N₄ photocatalysts materials were synthesized by a conventional thermal condensation method using melamine as a precursor under treated at the various annealing temperatures (450 °C, 500 °C, 550 °C, 600 °C and 650 °C). All as-synthesized samples were characterized and confirmed by a several techniques, such as, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectrometer (DRS), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) specific surface area. XRD and FTIR results confirmed that the as-synthesized g-C₃N₄ samples were completely synthesized at annealing temperature of 500 °C. SEM images showed the morphologies of the g-C₃N₄ samples had more flake-like structures upon the increasing of annealing temperatures. While DRS results indicated that the absorption edges of as-synthesized g-C₃N₄ samples were shifted to visible-light region, except the sample as-synthesized at 650 °C (g-C₃N₄-650 °C). Moreover, the photocatalytic properties of metal-free g-C₃N₄ photocatalyst materials were evaluated by degrading of MB dye solution under natural sunlight irradiation for 100 min. The results revealed that the highest photocatalytic activity was exhibited by the sample synthesized at 600 °C, which the apparent rate constant (k_app.) was 0.0291 min^-1. The orders of activities as: g-C₃N₄-600 °C > g-C₃N₄-650 °C > g-C₃N₄-550 °C > g-C₃N₄-500 °C > g-C₃N₄-450 °C. Hence, the metal-free g-C₃N₄ photocatalyst appears to be an attractive-material for water or wastewater purification applications over activated by sunlight irradiation.

Abstract: Double-layered graphene sheets (DLGSs) as a new type of nanocomponents, with special mechanical, electrical and chemical properties, have the potential of being applied in the nanoelectro-mechanical systems (NEMS) and nanoopto-mechanical systems (NOMS). In DLGSs structure, the two graphene sheets are connected by van der Waals (vdW) interaction. Thus, it can exhibit two vibration modes during the propagation of the flexural wave, i.e., in-phase mode and anti-phase mode. Based on the Kirchhoff plate theory and the nonlocal elasticity theory, Hamiltonian equations of the DLGSs are established by introducing the symplectic dual variables. By solving the Hamiltonian equation, the dispersion relation of the flexural wave propagation of the DLGSs is obtained. The numerical calculation indicates that the bending frequency, phase velocity and group velocity of the in-phase mode and anti-phase mode for the DLGSs are closely related to the nonlocal parameters, the foundation moduli and the vdW forces. The research results will provide theoretical basis for the dynamic design of DLGSs in micro-nanofunctional devices.