Advanced Materials Research Vol. 879

Abstract: Lead iodide (PbI₂) thin films were successfully prepared by thermal evaporation method on a glass substrate at room temperature. The structural analysis of these films was done by XRD. The results revealed that the crystallite size increases when increasing the film thickness and annealing temperature. In addition, the preferred growth orientation was 001 for all the samples.

Abstract: Dry machining is one of the ways to achieve a reduction of cooling lubricants, as well as reduced environmental pollution and lower health risk to workers. This leads to higher mechanical and thermal loading on cutting edges. The adaptation of cutting tools to the requirements of dry machining includes the optimisation of manufacturing technologies, the development of cutting materials of sufficient toughness and high hot hardness, the design of tool geometries as well as the coating of tools [.

Abstract: In this study, the applications of CdSe/ZnS quantum dots (QDs) and its role in advanced sensings has been explored. The CdSe/ZnS was synthesized by using hot injection method with the shell ZnS layer was made using successive ionic layer adsorption and reaction (SILAR) method. The morphology of the CdSe/ZnS QDs was studied using Transmission Electron Microscope (TEM) and the average particle size was in 10-12 nm range. The prepared QDs were optically characterized using spectrofluorescence and strong emission was observed at 620 nm. Comparison of the fluorescence emissions of CdSe/ZnS capped with various capping ligands such as L-cysteine, thioglycolic acid (TGA), mercaptopropionic acid (MPA), mercaptosuccinic acid (MSA) and mercaptoundecanoic acid (MUA) were studied. The CdSe/ZnS capped with TGA gave the strongest fluorescence emission compared to others.

Abstract: One major concern in maintaining pipeline structural integrity is failure due to corrosion defects. Various tests and codes had been established to assess the corroded pipelines. Burst test is one of the tests being conducted in the lab to assess the integrity of the pipelines. The advancement in computer technology had made the Finite Element Analysis (FEA) capable to simulate the burst test numerically. The objective of this study is to estimate the burst pressure of a corroded pipeline by using FEA. First, Ultrasonic Testing (UT) scan was carried out to establish the corroded pipe profile. FEA was then conducted to simulate the experimental procedure of the actual burst test. Several models were built and simulated by considering the number of defects, their depth and shape as the varying parameter in each simulation. All models were properly constrained and pressurized internally in determining the burst pressure (p_b) of the corroded pipeline. The result obtained by FEA was analyzed and compared to the actual burst test, ASME B31G and DNV-RP-F101 codes. Lastly the best model of FEA was proposed.

Abstract: Different concentrations of Ni-doped anatase TiO₂ nanoparticles were prepared by ice-bath co-precipitation method to examine the effects of various Ni²⁺ concentrations on the power exchange mechanism in photovoltaic performances of dye-sensitized solar cells (DSSC). X-ray powder diffraction (XRD) revealed a single anatase phase present in all samples together with three times reduction of particle size with the addition of Ni²⁺. Nanoparticle size exhibited better uniformity under scanning electron microscopy (SEM) with an increase of Ni²⁺ ions. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the formation of Ti-O-Ni bonding due to sharpened and enhanced intensity of the bands in the range of 500-1000 cm^-1 and 910-1030 cm^-1. Ni²⁺ concentrations also increased both open-circuit voltage (Voc) and short-circuit current (I_sc). The optimum concentration of Ni-doping obtained was at 0.075M of Ni which shows a maximum DSSC efficiency of 0.38%.

Abstract: The effect of electron beam (EB) irradiation at different doses on the magnetic, microstructure, morphological and thermal properties of NiFe₂O₄/Thermoplastic Natural Rubber (TPNR) nanocomposite was investigated. The NiFe₂O₄/TPNR nanocomposite samples were prepared by using a Haake mixer in weight ratio of 12:88. The TPNR matrix consists of natural rubber (NR), liquid natural rubber (LNR) and high density polyethylene (HDPE) in weight ratio of 20:10:70. The samples were irradiated using a 2 MeV EB machine in doses from 0 - 200 kGy. Magnetic properties studied by using the vibrating sample magnetometer (VSM) at room temperature showed that the values of saturation magnetization (M_S), remanence magnetization (M_R) and the coercivity (H_C) value increased with increasing doses of irradiation. The increase in M_S and M_R values is attributed to the increase in concentration of Fe³⁺ ions at octahedral B-site and decrease of concentration at the tetrahedral A-site in the NiFe₂O₄ cubic structure. X-ray diffraction (XRD) analysis of the samples showed that peak intensities decreased and the width of the peaks increased with increasing doses of irradiation. Scanning electron microscope (SEM) image of the nanocomposite cross section showed the presence of defects which is more visible with increasing doses of irradiation. In the case of thermal properties, differential scanning calorimetry (DSC) analysis showed that the crystallization temperature (T_c) and the degree of crystallinity (X_c) of the nanocomposite samples decreased with increasing doses of irradiation due to crosslinking of polymeric chains which hinders the growth of crystals.

Abstract: The mechanical properties and microstructures of WC-Co are highly dependent on its cobalt content, grain size of the WC particles and sintering temperature. In this work, the effect of addition of VC powder on the mechanical properties and microstructures during the consolidation of process will be investigated. The WC-Co and WC-Co-VC cutting tool inserts were fabricated using powder metallurgy route. The powders were wet mixed with heptane in turbula mixer for three hours, dried and then granulated. The mixed powders were uniaxially pressed at a pressure of 625 MPa and cold-isostatic pressed at a pressure of 200 MPa. The compacted samples were sintered in the temperature range of 1350 1450°C under nitrogen-based atmosphere. The mechanical properties of the samples are analyzed using Vickers microhardness tester, universal tensile machine and the microstructures of the sintered sample were observed using field emission scanning electron microscope. Microstructural examinations showed that VC particle is good as grain growth inhibitor as a result of good precipitation of VC in WC grain boundaries. However the addition of VC in WC-Co hardmetal resulted in the reduction of hardness and transverse rupture stress due to increase of pores in the microstructures of sintered samples.

Abstract: Microwave sintering technology has become attractive and gained interest among material researchers due its capability and advantages over conventional sintering. Since two decades ago, intensive researches on microwave sintering have been carried out to sinter ferrous and non ferrous material purposely to produce composites with enhanced properties not achievable via conventional sintering. In this research, the effect of sintering temperature on the microstructure and properties of the sintered 84Fe-11Cr-5Al₂O₃ composite was investigated. Sintering was carried out in a tubular microwave furnace HAMiLab-V3 under N₂ atmosphere. The sintering temperatures were selected between 1100°C to 1400°C with increment of 100°C. A study of microstructure and physical properties was carried out on sintered samples. It was observed that, relative density and porosity was slightly changed with increasing sintering temperature and hardness increased tremendously at sintering temperature of between 1300oC to 1400°C.However, the results showed that the optimum sintering temperature was at 1400°C.

Abstract: Natural rubber (NR) latex is widely used in the manufacture of thin film barrier products such as gloves and condom. However, due to its low T_g, film casted from NR latex is soft and tacky, and needed to be strengthened to produced high performance products. Films of prevulcanized natural rubber latex (PVNR) blended with nanosized copolymer of n-butyl acrylate/butyl methacrylate (BA/BMA) were prepared at three different ratios of acrylate copolymer: PVNR. The tensile strength and elongation at break of films prepared decreased with increasing ratios of acrylate copolymer:PVNR. FESEM images showed the occurrence of agglomeration of the acrylate copolymers with PVNR molecules. The degree of agglomeration of the blended molecules increased with percentages of copolymer added. The decrease in the tensile strength and elongation at break may due to the agglomeration of the blended molecules suggesting poor dispersion and/or destabilization of PVNR molecules.

Abstract: Ionic liquids have been recognized as an alternative solvent applicable in synthesis, separation, catalysis and electrochemistry. However, the synthesis costs, performance efficiencies and problems related to waste waters contaminated with ionic liquids are the major issues that need to be considered. Thus, recovery method is one of the alternatives to overcome the current issues. 1-butyl-3-methylimidazolium-based ionic liquids were chosen for the study. The recovery process was conducted in two steps; water-washing and recovery using solvent. All the selected ionic liquids were extracted with water and BMIM CH₃SO₄ was 100% recovered. However the ionic liquids contained high percentage of water which may change the properties of the ionic liquids. This current work has studied not only on the performance of recovery, but also on the properties and the behaviour of the ionic liquids to be further reused in a particular application.