Magnesium nanocomposites are promising materials for weight and strength critical engineering and biomedical applications. The addition of nano-particles to magnesium can improve hardness and strength without detrimental effect on the ductility which tends to occur when micron-size particles are added. Examples of magnesium nanocomposites reinforced with ceramic and metallic particles are provided and the microstructure, grain size, tensile, compressive and dynamic behavior are discussed.
Abstract: Reliability analysis of dense and porous sintered clay-based ceramic was compared using three-parameter Weibull model. The raw and the sintered clay at temperatures 900-1300°C were characterized using XRF and XRD. The raw clay (dense) and clay mixed with cassava starch (porous) were compacted and sintered at 1300°C. Flexural strength of the dense (24.11-46.56MPa) and the porous (13.58-23.26MPa) sintered clay were determined using three-point bending test. The results were analyzed by three-parameter Weibull probability distribution using Minitab 15 software at 95% confidence interval. Scale and threshold parameters of the dense sintered clay were higher than that of the porous sintered clay. However, the Weibull modulus of the porous ceramic was higher than the dense ceramic. The morphology of the porous sintered clay shows a relative distribution of porosity while the dense ceramic shows a random distribution of cracks. Three- parameter Weibull is a suitable tool to model the reliability of dense and porous sintered clays.
Abstract: Crosslink of recycled polypropylene with polyaniline (rPP-PANI) have been prepared via ultrasound extrusion. The concentration of PANI used in the research was varied from 0 to 10 wt% and that of dicumyl peroxide (DCP) was fixed in 1 phr loading of PANI. To examine the morphological structure of the blends, fill emission scanning electron microscopy (FESEM) was conducted. The increasing loading of polyaniline (PANI) has promoted a slight improvement in both elastic modulus and tensile strength at 4 wt% and impact strength at 10 wt%. However elongation at break showed a decrease at all PANI loadings. The FESEM micrograph confirmed good dispersion of nano-PANI on rPP matrix to form crosslinking between rPP matrix and PANI.
Abstract: Formation of thin and continuous layer of thermally grown oxide (TGO) in thermal barrier coating (TBC) are essential in order to avoid coating failure for high temperature applications. As-sprayed high velocity oxy-fuel (HVOF) bond coat can provide more uniform TGO layer in TBC system and much less oxide compare to air plasma spray (APS). In this paper, both APS and HVOF method are used to deposit NiCoCrAlYTa bond coat on Inconel 625 substrate followed by topcoat, YSZ deposition. Pre-oxidation process was done in normal oxygen furnace at 1000°C for 12 to 24 hours to study the characteristic of TGO formation via these two different methods. From the result obtained, it shows that HVOF method provide better TGO formation as compared to APS.
Abstract: Owing to its beneficial material properties, Al-Mg2Si in-situ composite has recently received wide attention and application in the manufacture of automotive and aerospace components. Melt treatment of the in-situ composite with the addition of Ce has resulted in a change in the primary and eutectic Mg2Si phases to refined morphology, which would be expected to improve the mechanical properties of the composite. Characteristic parameters of Mg2Si particles have been investigated via thermal and microstructural analysis. This has revealed that the addition of 0.8wt.% Ce produced optimum refinement effects on Mg2SiP because the coarse structure has been changed to a polygonal shape and reduced in size. Similarly, the flake-like morphology of Mg2SiE has been transformed into a rod-like or fibre form in addition to reduction of the eutectic cell area. The result also showed an increase in nucleation temperature TN of Mg2SiP while depressed for Mg2SiE, which also corresponds to the refinement morphology effect.
Abstract: Oxidation behaviour of in-situ melted pure aluminium was investigated. The granules were heated in ceramic investment casting moulds between 700 and 850°C, for the duration of 30 and 60 min in air using high temperature muffle furnace. The product was visually inspected macroscopically for the geometry and appearance. Scanning electron microscope (SEM) together with energy dispersive x-ray spectroscopy (EDS) was employed to analyse the oxidation characteristics of the product. Macroscopically, the granules failed to melt and unable to produce a casting even when the temperature was increased to 850°C. The surface of the granule experienced oxidation and spalling. Both temperature and heating duration were found to influence geometry, appearance of the product and oxidation behaviour. The oxide layer encapsulated the granule during in-situ melting of Al granules was found to be Al2O3.
Abstract: A nano-sized zeolite has been prepared in an autoclave, using tetraethoxysilane (TEOS), tetrapropylammonium hydroxide (TPAOH) and H2O at various hydrothermal synthesis temperatures. Using transmission electron microscopy and particle size analysis, the size of the nano-sized powders was revealed to be 10–300 nm and its distribution was uniform and spherical, depending on the hydrothermal temperature. X-ray diffraction analysis confirmed that the nano-sized powder was the silicalite-1 zeolite. A coating sol could be prepared by the proper combination of these nanoparticles with a solvent. The resulting coating on the glass substrate showed an antireflection effect, with less than 2–3% average reflectance over the visible range. In addition, the effect of silver nanoparticles in the silicalite-1 zeolite on antibacterial performances was carried as a function of the amount of nano-sized silver used. With increasing amounts of nano-sized silver, the number of colony forming unit decreased and became almost to zero.
Abstract: In this article, the results obtained from a study carried out on the plasma post-treatment of diamond-like carbon (DLC) films using an oxygen/tetrafluoromethane (O2/CF4) gas mixture is reported. The surface morphology and chemical bonding of the films before and after the plasma post-treatment were characterized using atomic force microscopy (AFM) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The effect of adding CF4 to the O2 plasma on the wettability of the films was also examined using contact angle measurements. The results indicate that the surface roughness increased with the addition of CF4 to the O2 plasma, whereas oxygen-and fluorinated-based functional groups were generated on the surface of the DLC films submitted to O2/CF4 plasma post-treatment. The surface energy also decreased with increasing CF4 fraction, causing the surface of the films to be hydrophobic. Furthermore, the films containing 20% CF4 exhibited higher hydrophilic stability than the others. Thus, the addition of a small amount of CF4 to O2 plasma can be considered beneficial in improving the hydrophilic stability of surface of DLC films.
Abstract: This works focus on an enhancement of dye-sensitized solar cell performance by improving photoanode which directly relates to shunt resistance and series resistance of the cell. Polyethylene glycol solution was prepared by dissolved polyethylene glycol in weight ratio of 10 and 30% in distilled water. ZnO past was prepared by mixing ZnO into polyethylene glycol solution, screened by doctor blade technique on fluorine doped tin oxide glass substrate and annealed at 450 °C for 1 h. The power conversion efficiency and fill factor were achieved as 0.81% and 0.44, respectively, because internal resistances were improved. The internal resistances were found that shunt resistance increased up to 4.35% and series resistance decreased down to 8.00% for 30% weight ratio of polyethylene glycol. These indicated that electron transfer in the cell was achieved in pathway direction.