Advanced Materials Research Vol. 979

Abstract: The effect on performance of single direct ethanol cell due to ethanol solution concentrations (5%, 10% and 15% by volume, ambient temperature (and), continuously changing of ambient temperature ( and), load resistance ( and) and air circulation through the cell were investigated experimentally in this research. The results showed that fuel cells have a high performance at high concentration of ethanol solution, high ambient temperature or operated in the wide range of continuously changing of ambient temperature. The performance was measured by the amount of the initial voltage, current and power obtained from fuel cell. But increasing air circulation through the fuel cell does not affect the performance of cell. The voltage and power drop obtained from the fuel cell increase with varying resistance load. But the current decreases with increases resistance load.

Abstract: The giant magnetoresistance (GMR) effect in FeMn/NiCoFe/Cu/NiCoFe spin valve prepared by dc opposed target magnetron sputtering is reported. The spin valve thin films are characterized by Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and magnetoresistance ratio measurements. All measurements are performed in room temperature. The inserted 45 mm thickness FeMn layer to the NiCoFe/Cu/NiCoFe system can increase the GMR ratio up to 32.5%. The coercive field to be increased is compared with different FeMn layer thickness. Furthermore, the coercive field (Hc) decreases with increasing FeMn layer thickness. Magnitude of coercive field is 0.1 T, 0.09 T and 0.08 T for FeMn layer thickness is 30 nm, 45 nm and 60 nm, respectively. The FeMn layer is used to lock the magnetization in the ferromagnetic layer through the exchange anisotropy. This paper will describe the development of a GMR spin valve and its magnetic properties.

Abstract: The pure TiO₂ and SnO₂-TiO₂ thin films on glass substrate were fabricated using a sol-gel dip coating technique. The thin films were annealed at the temperature of 700 °C for 2 h with the heating rate of 10 °C/min. The microstructures of the fabricated thin films were characterized by SEM and XRD techniques. The photocatalytic activities of the thin films were also tested by the degradation of methylene blue (MB) solution under UV irradiation. Finally, hydrophilic or self-cleaning properties of thin films were evaluated by measuring the contact angle of water droplet on the thin films with and without UV irradiation. It was found that 1 %mol SnO₂-TiO₂ thin films shows the highest of photocatalytic activity and provide the most self-cleaning properties.

Abstract: This research aims to study the effect of sludge from water treatment plants on the properties of pottery such as density, compressive strength, water absorption, and porosity.The composition of sludge from water treatment plants added to the clay varies, at percentages of 0%, 10%, 20%, 30%, 40%, and 50%, controlled by weight. The results showed that the composition of 10% by weight of sludge from the water treatment plant yields the ultimate pottery properties, with 12.63 MPa of compressive strength, 1.85 g/cm³ of density, 14.24% of water absorption, and 26.34% of porosity.

Abstract: Ho³⁺ doped zinc bismuth borate glasses of the composition 10ZnO : 30Bi₂O₃ : (60-x)B₂O₃ : xHo₂O₃ (where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 mol%) were fabricated by conventional melt quenching technique. In order to understand the role of Ho₂O₃ in these glasses, the density, molar volume and optical spectra were investigated. The molar volume decreases with an increase in Ho₂O₃ content, which is attributed to the structure becomes more compacted. The absorption spectra of Ho³⁺ doped in zinc bismuth borate glass correspond to several bands, which are assigned from the ground state, ⁵I₈ to ⁵G₅ (420 nm), ⁵G₆ + ⁵F₁ (451 nm), ⁵F₂ + ⁵F₄ (538 nm), ⁵F₅ (643 nm) and ⁵I₅ (1152 nm). Moreover, the optical basicities were also theoretically determined.

Abstract: Yellowish-brown inorganic pigments having a high near infrared solar reflectance have been synthesized. In this research, Fe₂O₃ was used as the host component, whereas, the mixtures of Sb₂O₃, SiO₂, Al₂O₃, and TiO₂ were used as the guest components. The guest components were investigated over a range of 36 different compositions. The results showed that the pigment, denoted by YB32, with a composition of Fe₂O₃, Sb₂O₃, SiO₂, Al₂O₃, and TiO₂ of 65, 15, 10, 2 and 8 wt.% respectively, generated a maximum near infrared solar reflectance of 40.8% while the YB3 pigment was found to have a minimum reflectance of 29.3%. The CIE L*a*b* colour index was used to measure the yellowish-brown pigment colours. The YB32 and YB3 pigment powders were also characterized by powder X-ray diffraction technique. It was found that the YB3 powder developed a new phase, FeSb₂O₃, which is mainly responsible for the decrease in the near infrared solar reflectance.

Abstract: Step-heating (single-and four-step heating) was used in the melt-mixing preparation of linear low density polyethylene (LLDPE)/multi-walled carbon nanotube (MWNT) composites. The MWNT in the composites were used at volume fractions of 0, 1, 3, 5, and 10 vol% (four-step heating), and 0, 1, 3, and 5 vol% (single-step heating). The effects of the heating steps on the microstructure of the LLDPE/MWNT composites were studied. An ultimate tensile testing machine and an impact testing machine were used to characterize the mechanical properties of the composites. The sample prepared using four-step heating had a lower porosity than the sample prepared using single-step heating. The sample with 3 vol% MWNT that was prepared using four-step heating had tensile strength, elastic modulus, and impact strength values that were higher than those of the other samples.

Abstract: The influence of damages on the insulator’s surface in the distribution system is investigated in this paper. The circular resin is used as the specimen under high voltage direct current (HVDC) between the electrodes with diameter of 2 mm and distance between both electrodes are 35 mm. There are three cases in the experiment and it was tested in environmental condition under dry surface, single droplet and double droplets. The HVDC had been applied to the electrodes, the level of applied were 5, 10, 15, 20, 25, 30 and 35 kV. The results show that the arc occurs rapidly in the case of single and double drops with compared to dry surface. The movements of the water drop of the single and doubles are pretty similar, but the arc occurs quickly in the double drop in comparison with single drop owing to double drops stretch to each other. The double drops take a lower voltage on stretching, whereas the single drop takes higher because the double drops have much more densities than single drop. Besides, the double drops act as a bridge allow the electrical field generated from both electrodes pulled them resulting in arcing easily. In conclusion, the droplets on the surfaces cause the leakage current and it has an effect on the stability of the distribution system.

Abstract: This work, surface fluorination process was used for improvement photocatalytic activity of TiO₂. Photocatalytic activity was observed by degradation of methylene blue (MB). TiO₂ nanopowders were prepared by sol-gel technique from titanium-tetraisopropoxide (TTIP): 2-propanal (2-PP) with the ratios of 1:5, 1:15, and 1:30 (V/V) then adjusted pH by nitric acid at 2. The result showed that grain size of TiO₂ powder decreased as 2-PP ratio increase. The grain sizes of TiO₂ were in the range of 14-25 nm. Photocatalytic activity was considered by characteristic time constant. The results showed that F-TiO₂ presented higher photo-degradation than naked TiO₂. At 1:30 for TTIP: 2-PP ratio with improvement by surface fluorination (F-TiO₂) could degrade MB faster than other samples under weak-UV at irradiation time of 1 hr. The 1:30 sample degraded MB reach to 96%. The results led to conclude that surface fluorination is the good process to improve photocatalytic activity for TiO₂.

Abstract: This research article was presented the thermal conductivity of cement pastes containing nanosilica. The effects of nanosilica particle size and concentration determined by mixing three nanosilica particle sizes of 12, 50 and 150 nm, using nanosilica were of 1-5 wt%. The water to binder ratio of 0.5 was used. The thermal properties test were subsequently measured in terms of thermal conductivity coefficient using ISOMET 2114. The thermal conductivities of cement paste is thus numerically calculated and the predictions are compared with the existing experimental data. A unifying equation for four fundamental effective thermal conductivity structural models (Series, Parallel, one-dimensional heat flow, Maxwell’s model) was derived. The best prediction was provided by a composite model that combined the Maxwell’s model. Consequently, applications of nanosilica cement paste in building constructions may be an interesting solution in order to improve sustainability and building energy efficiency.