Advanced Materials Research Vol. 1133

Abstract: Multilayer coating onto orthopedic implants has been studied extensively due to their excellence mechanical and biological properties. A multilayer coating was coated onto metal implants to prevent the leaching of metallic ions into human body. This paper aims to study the hardness of multilayer coatings of Chromium (Cr), Chromium Nitride (CrN), Chromium Carbonitride (CrCN) and Zirconium Nitride (ZrN) by Physical Vapour Deposition (PVD). The deposited multilayer coating was characterised by Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and Energy Dispersive X-ray (EDX). Cr, CrN, CrCN and ZrN have been successfully deposited onto stainless steel substrates by PVD. XRD analysis detected major peak in preferred orientation of (200) and other peaks with (111), (220), (311) for CrN cubic phase. For CrCN, XRD analysis detected only low intensity peaks of Cr₇C₃ and ZrN peaks with preferred orientation of (111), (200) with other peak (220), (311) and (222). Microvickers Hardness results showed an increment in hardness value from substrates with 160HV to 174HV for Cr, 236HV for CrN, 362HV for CrCN, 364HV for ZrN and 370HV for multilayer coatings.

Abstract: A graphene-based Surface Plasmon Resonance (SPR) biosensor is presented. Graphene layers added to a conventional gold thin film SPR biosensor leads to a drastic increase in sensitivity due to the increased biomolecule adsorption in the graphene layers. In comparison to conventional SPR sensors this produces a large change in the refractive index at the metal-dielectric interface. The reflection of light coupled into a SPR mode propagating along a thin Au-graphene layer surrounded by dielectric is calculated and compared to a conventional SPR sensor.

Abstract: The aim of this paper was to investigate the effects of cross-linked reaction on physicochemical properties of chitosan film by using genipin as cross-linker agent. Series of chitosan film samples with different amount concentration of genipin loaded (0-3 wt %) were prepared and characterized. The physicochemical properties of films were evaluated by Fourier Transform Infra-red (FTIR), UV-vis spectroscopy, Oxygen Transmission Rate (OTR), Scanning Electron Microscopy (SEM), water vapour and tensile test. The cross-linking reaction had affected on colour changing of chitosan film samples from light yellow to dark blue in line with the increasing of genipin concentration. Thus, UV-vis spectroscopy on the cross-linked samples showed the absorbance value at 600 nm wavelength due to genipin content. FTIR observation on cross-linked film samples showed no characteristic of –OCH₃ peak from genipin at 1444 cm^-1 which resulted by new covalent bonding occurred between chitosan and genipin. Cross-linking also had increased the oxygen barrier and reduced the water vapor rate through the film. Chitosan film sample with addition of 1 wt% genipin achieved the highest tensile stress average at 49.46 MPa compared to other samples while percent of elongation at break reduced with the increasing of genipin concentration loaded

Abstract: The recent introduction of selective laser melting (SLM) for the processing of medical grade cobalt chromium (CoCr) alloy has led to a complex shape fabrication of porous custom CoCr alloy implants with controlled porosity to meet the requirements of the anatomy and functions at the region of implantation. This paper discusses finite element (FE) analysis and mechanical characterization of porous medical grade CoCr alloy in cubical structures with volume based porosity ranging between 60% and 80% produced using SLM rapid manufacturing process. Analysis by FE is considered beneficial to predict the effective mechanical properties of the porous structures manufactured by SLM due to minimization of the need for expensive and time consuming physical testing. Cellular structures modelling for fabrication with Direct Metal Laser Sintering machine were designed to vary between 60% and 80% to study the effect of structural variation on mechanical properties of the cellular porous structure. ANSYS 14.0 FE modelling software was used to predict the effective elastic modulus of the samples and comparisons were made with the experimental data. FE results show that with the material properties in the functions of porosities, minimum mesh size of 0.2 mm for triangular shape mesh and boundary as well as load conditions as applied in this study, agreement in equivalent stress, strain and deformation with the experimental results can be achieved to some extent. The technique for FE in this study can be used to investigate stress distribution in three dimensional model of real bone.

Abstract: In this study, the focus was on the optimum design of laminate stacking sequences (LSS) of basalt fiber reinforced composite (BFRP) structure. Eleven rectangular composite panels with different stacking sequences and fiber orientations were analyzed. A three-point flexural test according to ASTM D790 was carried out in ANSYS to simulate the basalt fiber reinforced composite layup flexural strength. From the results, it was found that the composite structure layup of [0/0/45/0/0]_s has the highest strength among all samples.

Abstract: It is well understood that the fabrication process for glass fibre reinforced polymer (GFRP) composite is a near net-shape process. Nevertheless, drilling is often performed in the final stage in product component manufacture. Drilling of GFRP composites usually produces delamination damage that deteriorates the long-term performance of the composite materials. Hence, this project aims to obtain desired drilling parameters for minimum delamination damage under high-speed conditions. Taguchi L₂₇ orthogonal array has been employed for the experimentation and the controlled variables include spindle speed, feed rate, and drill bit. The results of Taguchi analyses showed that feed rate and drill geometry have major influence towards delamination damage.

Abstract: The aim of this study is to investigate the thermal properties of microencapsulated phase change material (μPCM) / multiwall carbon nanotube (MWCNT) composites. Several disc samples with 30mm diameter x 5mm width of μPCM/MWCNT composites were prepared with different mass fractions of MWCNT of 2, 4, 7 and 10 wt% using a compaction method. The thermal conductivity test was performed according to ASTM standard, while the latent heat property was calculated based on the theoretical equations. It was found that the thermal conductivity increase with mass fraction of MWCNT. However, the latent heat decreases with mass fraction of MWCNT. From these results, the optimized mass fraction of MWCNT approximately 5%, could be selected due it stable-form in thermal conductivity and latent heat capacity for electric vehicles (EVs) application. Furthermore, the reducing in melting time with increasing of MWCNT is accordance with the improvement of thermal conductivity.

Abstract: This study investigated the mechanical behavior of the treated and untreated kenaf with different matrix resin (epoxy and polyester) using the tensile and low velocity test. The long kenaf fibre was treated with 6% of sodium hydroxide (NaOH) solution for twelve hours in room temperature. The tensile properties of composites at different weight percentage (10,15,20 and 25%) were studied by using Instron Universal Testing Machine according to the standard ASTM D638. Impact test was conducted using an instrumented drop tower device at 10J incident energy level according to the standard ASTM D3763. The results of the study indicated that the epoxy resin reinforced with treated kenaf fibre exhibited higher tensile properties. On the other hand, the impact properties of polyester resin reinforced with treated kenaf fibre show better matrix bonding compared to those with epoxy resin matrices.

Abstract: Alumina hollow fiber membrane with asymmetric structure has been developed using phase inversion technique followed by sintering process. The formation of asymmetric alumina hollow fiber was influenced by a phenomenon known as hydrodynamically unstable viscous fingering. A desired morphology of the ceramic hollow fiber membrane, that consists of 52 % of finger-like and the rest is sponge-like structure, is tailored by controlled parameters during membrane fabrication process. The result shows that the ratio of alumina/PESf should be reduced to 6. At this ratio, the finger-like structure can be easily formed with inner and outer diameters were 1.11 mm and 2.05 mm respectively. From the given thickness, approximately 243 µm of finger-like length can be developed originating from the lumen of hollow fiber.

Abstract: Carbon(C)/Copper(Cu) Composites based materials were developed by associating both pressure and heat to the mixture of the powder. Three samples of different formulations were prepared by the powder metallurgy route in which the C-Cu powder were mixed with E-poxy Resin in a tubular mixer, pre-compacted using an automated hydraulic press machine, warm compacted using a warm compaction machine and finally post baked in oven. Each sample was subjected to density, hardness, transverse rupture strength and resistivity tests. The microstructures of the sample were observed under the scanning electron microscope. Test results of the developed samples show that sample C produced the highest physical, mechanical and electrical properties. However, the samples developed had lower physical, mechanical and electrical properties as compared with the commercial sample. This phenomenon was taught to be due to high porosity and insolubility of carbon and copper in the sample developed. Thus, father study will be done based on sample C formulation.