Applied Mechanics and Materials Vols. 799-800

Abstract: Proton Exchange Membrane Fuel Cell (PEMFC) is a device that generates electricity through an electrochemical reaction of oxygen air and hydrogen fuel. Thetransportofoxidantand fuel through the bipolarplatesis a significant factor affecting the cell performance. Currently, present work concentrates highly on flow field layout and channels design configurations. In this paper, the development two flow field layouts are discussed with different inlet/outlet channel ratio. Serpentine-paralleldesignisusedasthe base layout. The flow fields have inlet/outlet channel ratio of 1:1 and multiple inlet 2:1 configurations. Graphite is used as theplate material.Theanodeflowchannelis 2 mmx 1.2 mmx 2 mm meanwhile the cathode channel is 2 mm x 0.5 mm x 2 mm fora xbxwrespectively.Theactiveareais 25 cm² with 5 cmx 5 cm dimensions. The fields were fabricated by Roland EGX-360 Desktop Engraver machine that involved drilling and profiling process. The fuel cell assembly process is explained in detail. The gasketmaterialis made from two materials which are Polyimide and Silicon. A series of pre-conditioning experiments were carried out in both fuel cells for confident purposes.

Abstract: The use of low dosage gamma radiation and crosslinker was explored to reduce time and energy requirements for the crosslinking of the biomedical polymer poly(glycerol sebacate)-co-lactic acid (PGS-co-LA) and to determine the effect of these parameters on the polymer’s properties. Curing time was effectively reduced to less than 2 hours from the typical 48 hours required by thermal curing. Analysis using infrared spectroscopy identifies the bonds forming PGS-co-LA and confirms the formation in all low radiation dosage settings and crosslinker amounts. Increasing the amount of crosslinker did not change the polymer’s thermal properties significantly whereas increasing the radiation dosage from 5 kGy to 10 kGy resulted to more negative value of melting temperature and increase in heat of fusion. The sample with the highest amount of crosslinker irradiated at the lowest level of radiation dosage has the least negative melting temperature and lowest heat of fusion

Abstract: Graphite reinforced bio-based epoxy composites with different particulate fractions of graphite were investigated for mechanical properties such as tensile strength, elastic modulus and elongation at break. The graphite content was varied from 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, 30 wt.% by weight percent in the composites. The results showed that the mechanical properties of the composites mainly depend on dispersion condition of the treated graphite filler, aggregate structure and strong interfacial bonding between treated graphite in the bio-based epoxy matrix. The composites showed improved tensile strength and elastic modulus with increase treated graphite weight loading. This also revealed the composites with increasing filler content was decreasing the elongation at break.

Abstract: Cobalt-nickel (Co-Ni) nanowires were formed by electroless deposition in ethylene glycol under external magnetic field. The effects of initial Co (II) and Ni (II) concentration on the surface and morphology of the synthesized nanowires were investigated by x-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. An increase in the Co (II) concentration resulted in increase in diameter of the nanowires. However, the length of nanowires was observed to decrease. Higher Co (II) concentration resulted in a mixture of hexagonal close-packed and face-centered cubic Co-Ni nanowires. X-ray diffraction revealed that crystal growth occurred when the nanowires are annealed at 653 K for 10h.

Abstract: Zirconia (ZrO₂) nanotubes were synthesized by anodization of zirconium (Zr) foil in NH₄Fand (NH₄)₂SO₄ aqueous solution. Different surface preparation methods (electropolishing and etching) were applied on the Zr foil prior to anodizaton. In addition, the anodization time and NH₄F concentration were varied. The structure and morphologies of the nanotubes and their crystallinity were confirmed using scanning electron microscope and x-ray diffractometer, respectively. ZrO₂ nanotubes with large diameters and thick walls were formed at lower NH₄F concentration and longer anodization time. On the other hand, smaller nanotubes with thinner walls were produced when the NH₄F concentration was increased. The synthesized nanotubes were predominantly tetragonal ZrO₂ with small amounts of monoclinic ZrO₂.

Abstract: While manufacturing composite materials, reinforcement fillers inevitable collide with each other and subsequently they congregate to aggregates with different shapes. The shape of these nanoparticles aggregates are of great significance for the mechanical material properties and in consequence, knowing the percentage of aggregates of each shape within of a specific group of shapes can give an idea of the final properties of the material. This work classifies aggregates, a new dataset of 5713 carbon black aggregates gathered based on transmission electron microscopy image processing, using several classification trees and rule-based methods. Based on these methods several models are built, trained and tested to perform the classification. And then, the most reliable and accurate model to classify aggregates is selected, obtaining a testing accuracy of the 74.57% according to their shape.

Abstract: The combinations of polymer resin and glass microballoon are the main materials used to produce syntactic foams. Syntactic foam is a lightweight material that has good mechanical properties and is commonly used as a component for structural materials in civil construction, aerospace and marine applications. Hence, it should have suitable mechanical properties, particularly good compression behaviour. In the present study, the results obtained from compression tests are compressive strength, elastic modulus and specific compression that decrease when increasing of glass microballoon contents (2.0 wt.%, 4.0 wt.%, 6.0 wt.%, 8.0 wt.% and 10.0 wt.%) and also neat resin. The highest strength value for compression testing is owned by 2.0 wt.% which is 88.9 MPa, while the lowest strength is 43 MPa that belongs to 10.0 wt.% of glass microballoon. This shows that the density and weight percentage of glass microballoon in these syntactic foams affect compression properties. Therefore, a further study should be conducted, which includes the effect of compressive failure mechanism.

Abstract: This paper discusses the film coating formation mechanism after an anodizing process carried out in AA6061 with a varying potential between 15-30V. The electrolyte used to be 1M H₃PO₄ with titanium as the cathode. From this study, it was found that after the anodizing process the pore uniformity occurs with a size varied from 1.09-5.74 μm become 2.78-4.56 μm. There was also an increase in the titanium content on the deposition surface about 21% and was achieved at an electric potential of 25V where titanium in the pore penetration occurs up to the depth of 5 μm.

Abstract: The glass-forming area in the system SiO₂-P₂O₅-Al₂O₃-MgO-Na₂O is determined utilizing reagent grade chemicals. The obtained glasses are characterized using FT-IR, DTA, DSC, TMA and SEM. The multicomponent, mixed network glasses exhibiting low coefficients of thermal expansion, fairly high softening temperatures (at Al₂O₃/P₂O₅ ˃1) and good chemical durability, are made of SiO₄, AlO₄ and PO₄ polymerized tetrahedral units. AlPO₄ groups incorporated in the network structure increase thermal stability and modify the crystallization behavior, rendering it a slow process requiring high temperatures and / or prolonged heating times. Ceramization is accomplished through a multistage process depending mainly on the AlPO₄ content which is determined by the Al₂O₃/P₂O₅ ratio. At Al₂O₃/P₂O₅≈1, AlPO₄-high cristobalitic form is the first to crystallize in bulk, followed by farringtonite Mg₃(PO₄)₂. At Al₂O₃/P₂O₅˃ 2, platy corundum is the main crystallizing phase. Microporous glass-ceramics are obtained via acid leaching of either some or all of the crystallized phases, or through dissolving of the glassy matrix and preserving a network of one or more of the crystalline phases. Selected phases of less chemical durability have been removed, to leave a network of the most chemically resistant phases AlPO₄ and amorphous silica. On the other hand, the amorphous silica matrix containing Na₂O, MgO and P₂O₅ has been leached out in glasses having fibrous corundum as the main crystallizing phase to produce a microporous material with a unique morphology, being made of what looks like a house of cards structure made up of deformed, randomly oriented corundum blades or sheets. Such morphology, is believed to provide a microporous material with an extremely high surface area.

Abstract: The conductive thin film was made based on bio-based epoxy and graphite compounded with its cross-linker (Methylene Diphenyl Diisocyanate, MDI) and further blended with disparate percentages of pretreated graphite. The preparation of this solution started by drop casting as thin films, where the thickness of thin film was set approximately ~0.1 mm. Optical microscope, Fourier transform infra-red spectroscopy (FTIR) and Ultraviolet-visible (UV-vis) spectrophotometer has been operated to diagnose Graphite/ biopolymer composites in order to have better and accurate results of this work. The current-voltage (I-V) characteristics of the composite thin film samples were measured at room temperature. This study shows the electrical conductivity was discovered and calculated by achieving conductivity of 10³ S/m as a prove that this thin film has the ability to conduct electricity.