Advanced Materials Research Vol. 576

Abstract: Surface modification by reinforcing ceramic particulates can give protection against wear and corrosion of metal. In this work, two different amounts of TiC powder of nominal size 45 to 100 µm were embedded on AISI 4340 steel surfaces by melting under a Tungsten Inert Gas (TIG) welding torch with an energy input of 2640 J/mm. The microstructure, geometry and hardness of the single track composite layers were investigated. The resolidified melt tracks were hemispherical in shape. With increasing TiC content, the melt dimensions reduced a little but the microstructure had a remarkable change. The track with 1.5 mg/mm2 TiC gave more un-melted TiC, partially melted TiC and agglomeration of ceramic particulates while the 1.0 mg/mm2 track dissolved most TiC particulates and precipitated carbides in the form of dendrite, globular and flower type particles; dendrites are almost absent in the 1.5 mg/mm2 track. A reduced TiC addition created more fluid melt which accelerated dissolution of TiC and that caused more carbide precipitation in the 1.0 mg/mm2 track compared to that with 1.5 mg/mm2 track. The 1.0 mg/mm2 track produced lower hardness of 1065 Hv compared to 1350 Hv for the 1.5 mg/mm2 track.

Abstract: This paper investigates the flexural and impact properties of kenaf-glass (KG) fibers reinforced unsaturated polyester (UPE) hybrid composite on a source of green composite. The matrix is kept constant with 70 % volume fraction while kenaf and glass fibers were varied, such as 7.5/22.5 v/v, 15/15 v/v and 22.5/7.5 v/v. The 30 % kenaf and 30 % glass are also used for the preparation of composite materials. The kenaf fiber was treated with 6% sodium hydroxide (NaOH) diluted solution for 3 hours. Hybrid composites are fabricated using sheet molding compound (SMC) process. The mechanical tests, such as flexural and impact are performed using ASTM D790-03 and ASTM D256-04 respectively. The study showed that the highest flexural strength was obtained from treated kenaf with 15/15 v/v KG fiber reinforced hybrid composite while untreated of 15/15 v/v KG composite showed the highest value of impact strength in this investigation. This can be concluded that 15/15 v/v KG fiber reinforced unsaturated polyester hybrid composite is the most appropriate hybrid composite which can be considered for many engineering structural applications, such as automotive, aerospace, construction or sports.

Abstract: Nanocrystalline silicon (nc-Si) thin films were deposited on glass and polytetrafluoroethylene (PTFE, teflon) substrates using Radio frequency (RF) magnetron sputtering. The effect of RF power and deposition temperature on the physical and structural properties of nc-Si on the glass and Teflon substrate was studied. The thin films properties were examined by Raman spectroscopy and field emission scanning electron microscopy (FESEM). We found that the thickness of thin films increased with increased RF power and deposition temperature. Raman spectroscopy results it showed that, with increasing RF power and deposition temperature can cause the changing of crystallinity on both glass and Teflon substrate.

Abstract: This paper reported on properties of sago starch that was compounded with montmorillonite (MMT) nanoclay to form biodegradable composites film. The film was fabricated via film casting method with glycerol as a plasticizer. The investigated biocomposites film was prepared at starch-glycerol/MMT weight fraction of 90/10, 85/15, 80/20 and 75/25. The physical properties of the film, namely thickness and density were studied and results show that incorporation of nanoclay as filler affects the biocomposites physical properties. Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) were used to analyze the film’s morphological properties and chemical characteristics, respectively. SEM shows that less clay content in the film produces homogenous phase and well dispersed of clay platelets within the starch matrix. FTIR summarizes that MMT nanoclay is able to form hydrogen bonding with starch.

Abstract: Zinc anode is electrodeposited from a 2-M zinc chloride electrolytic bath with varying ammonium chloride supporting electrolyte concentrations (0-5 M) and plating current density (0.1 – 0.6 A cm-2). The total charge quantity supplied during electrodeposition is fixed at 150 mAh. Alkaline zinc-air cell is fabricated using the electrodeposited zinc anode and characterized according to its discharge capacity at constant load current of 20 mA. The effect of various qualities of zinc electrodeposits on the cell discharge performance is discussed. It is found that zinc electrodeposits prepared from electrolytic bath of 5-M ammonium chloride and 0.5 A cm-2 plating current density produced zinc-air cell with the highest output energy i.e. 24 mWh. We observe that the influence of plating current density is more prominent than the plating bath formulation on the zinc anode performance in the cell.

Abstract: The thermal stability of kenaf sandwich panel core structures are presented in this paper. Sandwich core structures tested are of varying kenaf percentage being 10, 20 and 30 wt%. The result indicated that all composite have two step degradation processes due to the presence of kenaf in epoxy. From the discussion, increasing the kenaf percent ratio will decrease the percent residue.

Abstract: The aim of this study is to determine the morphology and water uptake behaviour of single fibre and leaf of Typha Latifolia. In order to study the morphology and water uptake properties of the fibre, a single fibre was taken out from the Typha Latifolia leaf. The leaf was divided into two-part that are top and bottom parts. From direct observation towards leaves, the leaf at the bottom part has more cavities compare to the leaf on the top parts of the tree. Based to morphology analysis, the fibres were found randomly held in the middle of the top part and there were spongy structures in the middle of the bottom part of the leaves. SEM analysis evidenced that a single Typha Latifolia fibre is from a bulk of fibre. A water absorption result at top part of the leaf is higher than bottom part of the leaf with 79.79% and 66.63%, respectively. It was observed that different part of Typha latifolia could absorb water with different percentages.

Abstract: The paper discusses sensitization characteristics in medium chromium Ferritic Stainless Steel (FSS) welds processed at two different grain refining conditions namely metal powder addition and cryogenic cooling. Tungsten Inert Gas (TIG) torch welded samples were exposed to 10% oxalic acid electrolytic etch for evaluation of sensitization. Empirical analysis indicated that, though both the grain refining conditions reduced the sensitization width relative to the conventional weld, the width was virtually nil with cryogenic cooling suggesting the elimination or reduction of sensitization. Similarly, the microstructure of cryogenically cooled welds showed no ditched grain boundary but aluminum powder treated welds revealed extensive ditching and none in titanium treated welds while knifeline attack was observed in welds treated with the mixture of aluminum and titanium powders.

Abstract: Carbon fiber reinforced plastic (CFRP) composites as high performance material in aerospace industry. The application of laser technology to cut the CFRP shows promising advantages. Therefore, several cutting parameters such as pulse energy, pulse repetition rate, cutting speed and pulse duration need to be taken into consideration. In this study, the effect of the aforementioned parameters on heat affected zone (HAZ), kerf width and taper angle were evaluated. The results showed that pulse energy and pulse repetition rate gave a significant effect on the cutting characteristic.

Abstract: Fabrication of micro and nanoscale components are in high demand for various applications in diversified fields that include automotive, electronics, communication and medicine. Focused ion beam (FIB) machining is one of the techniques for microfabrication of micro devices. This paper presents a review of FIB machining technology that include its parameter, responses, its important component systems, as well as the fundamentals of imaging, milling (etching) and deposition techniques. The application of FIB in micromachining is also presented.