Key Engineering Materials Vols. 471-472

Abstract: This paper presents a study of the quality of a surface roughness model for mild steel with coated carbide cutting tool on turning process. The experiments were carried out under wet and dry cutting conditions. The model is developed based on cutting speed, feed and depth of cut as the parameters of cutting process. This research applies the fractional factorial design of experiment approach to studied the influence of cutting parameters on surface roughness. The measured results were collected and analyzed using commercial software package called Minitab. Analysis of variances is used to examine the influence of turning factors and factor interactions on surface roughness. The result indicated that, there are inherent differences in surface roughness between wet and dry cutting process with the same parameters process model. Analysis of variance was found that feed parameter is the most significant cutting parameter, which influences the surface roughness. The most significant interactions were found between cutting speed and feed parameters for dry turning process. Therefore is a significant effect of using combination of the fluid for cooling the cutting operation.

Abstract: Nowadays, natural fibre-thermoplastics composites (NFPC) are replacing the conventional wood and timber due to its lower cost, avoid deforestation, higher strength-to-weight ratio and resistant to termites. These composites can be utilized for non-structural components of a building system such as decking, wall cladding, floor tiles and window frame. A natural fiber/plastic composite was produced by extrusion molding process to create a wall cladding profile. The raw materials used for the composites are 40% kenaf fibre and 60% polypropylene (PP). These materials were compounded through a twin-screw extruder and then cut into pellets. The moisture content found in the kenaf/PP composites (KPC) pellets was 2.89%. Therefore, the pellets required to be oven dried every time right before entering the hopper of the extruder. The temperature along the barrel was set to 180°C and the die head temperature is set to 165°C. At the end of the extrusion molding process, pressurized air was used for cooling the profile. Then, samples of the wall cladding were taken back to the laboratory for product quality assurance. Measurements of the samples show that the product experiences 3% of shrinkage in term of width and 1% of shrinkage in term of thickness. Water absorption test indicates an increase of 13.6% of weight after 24 hours immersion of water. Impact strength test was also conducted on the wall cladding samples and the mean result was 2.55 kJ/m². Tensile test on the extruded KPC product indicates a low tensile strength at 4.51 MPa and tensile modulus of 205.01 MPa. The sample also proven to be light weight as the density of the material was found to be 0.618g/cm³.

Abstract: Recycling glass is chosen as an alternative raw material in upgrading ceramic into glass ceramic. The main objectives are to determine the effect of sintering temperature and the recycled glass to ball clay weight ratio on glass ceramic produced from recycled glass. The recycled glass powders are prepared by crushing and grinding waste glass bottles to a particles size distribution below than 75 µm. The raw materials (recycled glass powder and ball clay) are characterised by Differential Thermal Analysis (DTA) and its composition is determine by X-Ray Fluorescence (XRF). The recycled glass powder are then mixed with the ball clay according to the ratio of SLSG to ball clay of 95:5 wt.%, 90:10 wt.% and 85:15 wt.%. Green samples of glass ceramic are then fabricated using Cold Isostatic Pressing (CIP) with constant pressure at 40 MPa. Sintering process is conducted at three different temperatures at 750°C, 850°C and 950°C with 1 h holding time. The sintered glass ceramic were then characterised using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses. Results of physical analyses and microhardness testing conducted according to ASTM C 373 and ASTM C 1327 showed that better properties is achieved at batch composition compromised of 85:15 wt.% ratio of recycling glass to ball clay and sintered at 850 °C. SEM micrographs showed that samples produced from this optimum batch composition provide more homogeneous and dense surface. Furthermore, XRD analysis indicates that crystalline phases evolved during sintering contributes to the final strength of the glass ceramic. These encourage further development on the glass ceramic samples which intended for structural applications.

Abstract: Cellulose and lignocellulose have great potential as nanomaterials because they are abundant, renewable, have a nanofibrillar structure, can be made multi¬functional and self-assemble into well-defined architectures. New methods for liberating these materials, including nanodimensional cellulose fibrils, macromolecules and nanominerals will be needed in order to use the techniques developed for other nanomaterials as platforms for creating new wood-based materials and products. Research findings showed promising results in application of nanotechnology at different aspects of papermaking. Electrospinning; chemical treatment followed by mechanical techniques; or mechanical isolation methods were applied by different research groups to prepare cellulose nanofibres.

Abstract: This study investigates the relationship of rheological properties of nanoparticles added to lead-free solders paste. For lead-free solder paste, a large number of combinations can be made from different elements. Every ingredient plays a role of the paste and the rheological properties. The effect of filler concentration was studied in this present investigation. Creep recovery, stress is applied on samples for a period of time and later release in order for it to recovery itself. In the other words, creep recovery involves a tensile specimen under constant load maintained at a constant temperature. Oscillatory tests were carried out to study the visco-elastic behaviour and paste stability. The visco-elastic behaviour of the paste lies between solid and liquid characteristic of the paste, which could be used to study the flow behaviour of paste during stencil printing process. From this study, it was found that the solid characteristic, G' is higher than liquid characteristic, G'' for all the samples. In addition, the results from the study showed that the 0.06 volume fraction sample system with a large yield point which G'= G'' has a higher cohesiveness and hence resulting in poor withdrawal of the paste during stencil printing process. The phase angle, δ was used to correlate the quality of the dense suspensions to the formulation of solder paste materials. Lower value of phase angle for 0.06 volume fraction sample system may indicating that the paste is very tacky compare to the other samples. As the demand for lead-free pastes increases rheological measurements can assist with the formulation of new pastes.

Abstract: In this paper, the developed new micro-meso method by the authors is used for the edge-effects analyses of various angle-ply laminates such as [10/-10]2s and [30/-30]2s. It is shown that the obtained stress-strain behaviors of laminates are in well agreement with the available experimental results. The stress variations through the laminate thickness and near the free edges are also computed and compared with the available CDM results.

Abstract: Composite cathode is a promising material to be used as electrodes in fuel cells. The fabricated composite cathode materials in this study are comprised of a mixture of submicron La0.6Sr0.4Co0.2Fe0.8O3- (LSCF6428) powders with two types of nanoscale ionically conducting ceramic electrolyte materials, samarium-doped ceria (SDC) and SDC-carbonate (SDCc). 30 – 50 wt% of electrolyte materials are added to the LSCF6428 cathode via the solid state method. The composite powders were ball-milled in ethanol and calcined at the temperature range of 800°C to 900°C for 2 hours in air. The composite cathode powders are characterised in terms of morphology and crystal structure. It is found that after calcining, the LSCF and the electrolyte materials retained their original structures as there was no chemical reaction between the two components. In addition, the LSCF-SDC composite cathode powders were found to exhibit a narrower distribution in size compared to the LSCF-SDC carbonate powders.

Abstract: (100-x) LiCF3SO3 + (x) CeO2 composite electrolytes were prepared using sol-gel technique followed by sintering at 300 °C for four hours. Structural property and conductivity of the prepared composite electrolytes were studied using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX) analysis and Impedance Spectroscopy. The XRD spectra show only crystalline peaks of CeO2 indicating that LiCF3SO3 exists in the form of amorphous phase. This is confirmed by SEM and EDX analyses. The highest ionic conductivity at room temperature is found to be in the order of 10-3 S cm-1 for the composite of 70 mol % LiCF3SO3 - 30 mol % CeO2. The conductivity of the composite electrolytes is observed to increase gradually with temperature.

Abstract: This paper presents the development of a mathematical model based on curved beam theory of composite pipes with irregular shapes under diametral loading. The analytical solution was validated through finite element models of the same pipe shapes under similar loading conditions. Four shapes (circular, elliptical, rectangular, and egg shaped pipes) were considered in this study. The analytical and finite element results were used to estimate the shape factor defined by the ratio of the maximum tangential stress of an irregular shape over the maximum tangential stress for a circular pipe. Comparison of the load-deflection curves for the four different shapes revealed that the egg pipe is the stiffest among the rest of the pipes while the square shape is the most flexible one. The analytical solution and finite element results were used to determine the shape factor for the four pipe shapes taking into account the circular pipe as the base shape. Both results were in good agreement and can be used as design guidelines for the irregular shapes without resorting to the conduct of any further testing.

Abstract: This paper presents a practical approach dealing with the development of safe working envelops for field operators to avoid any potential GRE pipe failure during installation. Finite element modeling was used to model the pipeline. Two different element types available in ANSYS library (Beam and Shell elements) were used in the analysis. Various pipe sizes subjected to typical loading conditions similar to field layout conditions were considered. The finite element models were used to estimate pipe deflection, the internal normal and shear forces as well as bending moments for each pipe section along its length from which the induced stresses were determined. The maximum tensile stress was calculated and compared to the failure strength of GRE for various lifting scenarios. A sensitivity analysis on the various parameters affecting the structural integrity of the pipeline was also performed. It was found that the beam element over predicts the threshold lifting height as compared to the shell element results. In most cases, the estimated threshold value for the lifting height causing potential pipe failure for all pipe sizes is 2 and 1.2 m for beam and shell elements, respectively. Moreover, the results showed that the minimum threshold height increases for smaller pipe sizes.