Advanced Materials Research Vols. 931-932

Abstract: Titanium dioxide (TiO₂) nanofibers with different particle sizes were fabricated using an electrospinning technique. The nanofibers were prepared from a mixture of titanium tetraisopropoxide and polyvinyl pyrrolidone (PVP). The scanning electron microscope (SEM) and the transmission electron microscope (TEM) were used to analyze the morphology and sizes of TiO₂ nanoparticles within the nanofibers. The particle sizes of TiO₂ were measured to be 17 nm, 28 nm and 35 nm for nanofibers calcined at 500 °C, 600 °C and 700 °C, respectively. Ultraviolet-visible absorption spectroscopy analysis and the application of the KubelkaMunk function reveal the size-dependent band gap energy of TiO₂ nanofibers. The band gap energies are measured to be 2.9 eV, 2.6 eV and 2.5 eV for TiO₂ nanofibers with average particle sizes of 17 nm, 28 nm and 35 nm, respectively.

Abstract: The characteristics of Nickel Aluminum Bronze alloy (NAB) after hot deformation were investigated. The NAB alloy have been studied by dilatometer according to study the influence of hot deformation on microstructure of NAB alloy by dilatometer in the temperature range 800 - 950 °C, strain rate 10s^-1 and cooling rate 40 and 100 °C/s. The experimental results showed that peak stress in relation to the involved deformation temperature, peak stresses at a constant strain rate decreased with an increase of deformation temperature. It was found that volume fraction of the β phase significantly increased with increasing temperature and cooling rate. The variation of this phase affected macro hardness of the investigated alloy. By higher temperatures, amount of β phase increased as well as the macro hardness of the NAB alloy.

Abstract: The use of biogenic materials to produce naturally based biomaterials has been widely studied. In this study, heavy metal content, phase transformation and physical characterization of Golden Apple Snail shell were investigated for use as a calcium source in the production of naturally based biomaterials. In order to investigate phase transformation, Golden Apple Snail shell was calcined at 600 °C, 700 °C, 800 °C and 900 °C. Small amounts of As and Pb were found in raw Golden Apple Snail shell. Calcium carbonate (CaCO₃, calcite) and calcium oxide (CaO) phases were observed in Golden Apple Snail shells after calcination at 600 °C and 800 °C. Fine white CaCO₃ (calcite) and CaO powders were prepared after calcination of Golden Apple Snail shells. The CaCO₃ (calcite phase) was completely transformed into a CaO phase at 800 °C. Phase transformation depended on calcination temperature and time.

Abstract: Biocompatible material called scaffold helps patient suffering from skin loss or skin disorder such as burn and ulcer. The scaffold allows the wound healing process to occur in suitable condition and heal faster. There are varieties of commercial scaffold available but it is also relatively expensive. This research seeking to develop new affordable scaffold using gelatin blended with carboxymethylcellouse (CMC) to strengthen the porous structure. Moreover, the strength of the scaffold by using thermal crosslinking technique is called dehydrothermal (DHT) treatment. At this stage, identification of material parameter, in this case, shear modulus is necessary. The behavior of the material is foam-like hyperelastic material. The large deformation theory has been use to derive the constitutive equation to obtain the engineering stress equation in form of Blatz-Ko hyperelastic model. The stress-strain curve obtained from compressing test. The curve fitting method was used to identify the shear modulus of the scaffold. As a result the scaffold with 80:20 gelatin-CMC ratios is dominant and shows highest shear modulus of 12.85±3.77 kPa. However, this is can be improved. Further discussion and suggestion is given at the end of the research.

Abstract: Mechanical response of polyurethane open-cell foam with electrodeposited copper coatings under compressive loads is investigated via experimental characterization. Commercially available open-cell polyurethane foam specimens are copper deposited using electroless and electro-deposition techniques. Thickness and composition of the coating are controlled by varying the deposition time to 30, 60 and 90 minutes. Micrographs of the coated foam structure show that the coating thickness is higher at the outer surface, and the averaged thickness linearly depends on the deposition time. The coated foam exhibits a stiffer compressive response than that of the uncoated one. When unloaded, the copper coating layers fracture at the center of foams ligaments, and fall off from the foam structure.

Abstract: Thin films of sodium cobalt oxide and zinc aluminium oxide were prepared onto ceramic substrates by a bipolar pulsed-dc magnetron sputtering system using a NaCoO₂ target and a ZnAlO target, respectively, under an argon atmosphere. Energy dispersive spectroscopy analysis revealed that the as-deposited films from the NaCoO₂ target comprised Na, Co, O elements, while those from the ZnAlO target contained Zn, Al, O elements. Cross-sectional view estimation by the scanning electron microscope indicated that the as-deposited Na-Co-O (NCO) and Zn-Al-O (ZAO) films had the thickness of 0.63 μm and 0.58 μm, respectively. X-ray diffraction analysis showed that the NCO thin films were grown in amorphous phase while the ZAO thin films exhibited hexagonal structure. From thermoelectric properties measurement, the p-NCO and n-ZAO films were found to exhibit the thermoelcectric power factor of 0.03 and 14.39 μW/mK², respectively. A thermoelectric module made from three pairs of the p-n thin film stripes provided the open-circuit voltage up to 26.0 mV for a temperature difference of 79.3 K. However, the module was unable to produce useful electrical current due to its high internal series resistance contributed from the NCO films.

Abstract: The aim of this research is to study heat transfer rate of impinging flame jet and cutting quality of steel plate using flame jet. The cutting torch was used for heating on the impingement surface, and it was used for cutting the steel plate samples. LPG at constant flow rate of 0.14 kg/s was mixed with pure oxygen at varied flow rate corresponding to equivalence ratio, =0.78, 0.93 and 1.16. The nozzle-to-plate distance was examined at h=3, 4, 5, 6, 7 and 8 mm. Heat transfer rate on the impingement surface was measured using water cooled heat flux sensor. In order to investigate cutting quality, steel plate with 6 mm in thickness was cut by this flame jet with cutting speed at 260 mm/min. The surface roughness, slag quantity and kerf characteristics were considered for cutting quality. The results show that the flame jet for condition of =0.78 at h=4 mm gives the highest heat transfer rate. The flame jet for condition of =0.93 at h=6 mm is optimal for using cutting steel plate in this study.

Abstract: The temperature of the surface of a material in a manufacturing process of plasma is very important information, while the results of measurements usually indicate the average temperature of the material. By using the method of numerical analysis, the distribution of temperature on the thickness of the material can be formulated using the heat conduction equation for material. Heat distribution that occurs is computed using a heat flux parameter input power, the heat transfer coefficient and surface area of the material. Simulations performed on the heat distribution PMMA and LiNbO3 crystal with thickness of 2 to 2.5 mm.

Abstract: At the present time, researchers try to find alternative fluids for being used as lubricants or hydraulic fluids that are biodegradable and environmental friendly. In this study, Refined-Bleached-Deodorized (RBD) palm olein was investigated whether it is such a potential candidate. RBD palm olein could be easily acquired since it is of the type used as cooking oil. The physical properties of both conventional hydraulic oil and RBD palm olein were tested and compared by an accredited laboratory. The performance of the hydraulic systems when using both fluids as working mediums were also tested and compared. The experimental results show that temperature significantly affected the performance of the hydraulic system when using conventional hydraulic oil, whereas the performance of the hydraulic system when using RBD palm olein barely changed with temperatures. At the temperatures below 60 °C, the RBD palm olein yielded less flow rate and less energy efficiency. However, for the temperatures above 60 °C, the RBD palm olein yielded slightly more flow rate and slightly more energy efficiency. It can be confirmed from this study that RBD palm olein can be used as an alternative hydraulic fluid.

Abstract: The objective of this work was to examine the microstructural changes caused by the carbonation of normalised cement mortar. Samples were prepared and subjected to accelerated carbonation at 20°C, 65% relative humidity and 20% CO₂ concentration. The main contributions of this study were: 1) a new way to determine separately the amount of calcium carbonate CaCO₃ produced by the carbonation of portlandite Ca (OH)₂ and that associated with the carbonation of calcium-silicate-hydrate C-S-H using only thermal analysis; 2) determination of the increase in the molar volume of the calcium-silicate-hydrate C-S-H due to carbonation using gas pycnometer, which indicated an increase of about 39 cm³ for 1 mole of C₃S₂H₃ carbonated. The results indicated that the amount of CaCO₃ produced by the carbonation of C-S-H is higher than that produced by the carbonation of portlandite.