Abstract: The reprocessing ability of recycled polypropylene (PP) has been investigated to evaluate the recycling feasibility in spur gear production. Up to 15 reprocessing cycles have been performed by injection moulding, and the effects on tensile properties including ultimate tensile strength, Young’s modulus and elongation at break have been studied. Results revealed that reprocessing ability of recycled PP spur gears could yield satisfactory quality as attractive as that corresponding to the virgin PP spur gear. The recycled PP gears resulted in more 10% variation in tensile properties during multiple processing. This effort might be a contribution to convince the industry to apply recycling of PP by means of multiple reprocessing in gear manufacturing.
Abstract: In this study, waste polyethylene terephthalate (PET) polymer binder systems were used to prepare copper-graphite metal injection molding (MIM) feedstock. A mixer and screw extrusion were used to achieve optimized feedstock, and the rheological properties of the resulting fluids were evaluated using a capillary rheometry to simulate the injection molding process. The solid loadings in the copper-graphite mixes were investigated in the ranges of 51-53% using PET binder system. The effects of shear rate (γ), solid volume fraction (φ) and temperature (T) on the rheological behavior of the copper/graphite MIM feedstocks are discussed.High viscosity trend was notably recorded as shear rate increased relatively. The results indicated that this feedstock system shows dilatant characteristic and lots of further work shall be conducted in attempt to establish this as an ideal binder system.
Abstract: Friction stir processing is a novel process evolved to fabricate surface metal matrix composites. Rice husk ash (RHA) is an agro-industrial waste and by product of rice husk. The feasibility of incorporating RHA powder into aluminium alloy AA6061-0 as reinforcement particles to make surface matrix composite via FSP is reported in this paper. The optical micrographs revealed a homogeneous distribution of RHA particles which were well bonded with the matrix in both first and fourth-passes of the FSP due to mechanical stirring. Microhardness of the stir zone SZ with the RHA particles of I-pass increased to about 106 HV, 40% higher than that of the base material 66 HV by dispersed RHA particles.
Abstract: Research on the use of thermal barrier coatings in internal combustion engine had contributed in achieving higher thermal efficiency, improved combustion and reduced emissions of the engine. Low thermal conductivity ceramics can be used to control the temperature distribution and heat flow in high temperature structural components due to its inherent thermal insulation properties. For this reason much has been and is being done on the study and development of ceramics for use in automotive engine components working under severe temperature conditions and heavy loads due to their inherent thermal and mechanical properties. The objective of the study is to review the contributions of structural ceramics in the development and improvement of some of the major automotive engine components working under severe conditions of temperature. It is expected that the study will serve as a useful guide for the selection of materials which can withstand severe conditions of temperature and heavy loads for a novel turbocharger and turbocharged engine applications.
Abstract: In this study, the potential of rust as a pigment in paint technology via sintering process was investigated. Iron (III) nitrate was the raw material used to make rust or iron oxide. The characteristics of iron oxide were analyzed. Moreover, iron oxide was mixed with other chemical components to make paint. The properties of paint in both liquid state and solid state were determined by portable field viscometer, pH indicator, glossmeter, pencil hardness test, and tape adhesive test. The optimum ratio of paint components for this study where used iron oxide as pigment. The other properties of pigments and paints will be conducted in the analysis study.
Abstract: Debinding process of injection moulded Ti-6Al-4V feedstock was divided into two parts: solvent debinding process to eliminate palm stearin (PS) and thermal pyrolysis to eliminate polyethylene (PE). Solvent debinding process used heptane at optimum temperature, 60°C to remove PS binder completely as temperature is the only parameter that can be optimized. Thermal pyrolysis parameters for removal of PE binder from the injected 65vol% Ti-6Al-4V feedstock have been optimized by using Taguchi method. Heating rate, temperature and time were the selected factors during experiment to be applied in the L9(34) Taguchi orthogonal array (OA) to find the best set of parameters to produce highest density of brown part. Thermal pyrolysis process was done at optimum parameters: heating rate: 5°C/min; temperature: 510°C; and time: 90 minutes. Analysis of Variance (ANOVA) was employed to find the best signal to noise ratio (S/N) to express the contribution of the factors towards quality characteristic. Based on the results, heating rate has the greatest contribution (54.63%), followed by duration time of thermal pyrolysis (24.40%) and temperature (19.25%).
Abstract: The mixing process of a newly developed binder system based on waste polystyrene (PS) and palm kernel oil (PKO) to produce feedstock for metal injection molding (MIM) using aluminium waste as metal powder is described. Since mixing is a critical step in MIM process, therefore the mixture of powder and binder should be homogeneous and moldable. In this study, aluminium powder produced from waste aluminium alloy was mixed with a new binder system consisting of waste polystyrene and palm kernel oil in a Brabender Plastograph EC rotary mixer. Several tests were performed to assess the homogeneity of the feedstock that was produced at 60 vol.% powder loadings. The tests conducted were density, binder burn-out and SEM morphology observation. It was found that the feedstock shows good homogeneity and suitable for further processing in MIM.
Abstract: In the present work, the rheological properties in terms of shear stress and viscosity of Kaolin/Polyether-Sulfone (PESf) of varying ratio were investigated by a rotating rheometer. The shear rate of Kaolin/PESf sample was measured at increasing interval shear rate. By assuming that the fluid behaves like a typical Non-newtonian polymeric liquid, the consistency index, K and flow index, n were able to be determined. Thus, the rheology behaviors of the kaolin/PESf suspension could be investigated at a wider range of shear rate. The shear stress was found to increase with increasing shear rate, with the rate of change quite apparent at low shear rate. At higher shear rate, the shear stress increases definitively with the increase of kaolin content. On the other hand, the viscosity decreased at a faster rate initially and slows down to monotonous rate as the shear rate increases. Evidently at increasing shear rate, the viscosity tends to become constant as the deviation become smaller which is also known as zero shear rate viscosity region.
Abstract: In this work, the oxidation behavior of Fe-20wt.%Cr alloys with different titanium contents: 0, 0.5, and 1 wt.% are studied as a function of time in air atmosphere. The samples were isothermally oxidized at 700°C for 24, 48, and 96 h in a box furnace. The area specific resistance of oxides formed at the alloys surface during oxidation is measured by four-point probe methods at 700°C for 24 h. For Ti containing alloys, surface morphology observation by SEM shows that a few of TiO2 particles formed on the top of Cr2O3 scales. Continous TiO2 layer was not formed at the alloys surface after oxidation. XRD analysis on the oxide scales of Fe-20Cr-Ti alloys confirms that Cr2O3 and TiO2 oxide formed on the alloys. Ti addition into the alloys increases the oxidation rates of alloys at the initial stages. Oxidation behavior of Fe-20Cr-0.5Ti and Fe-20Cr-1Ti alloys showed two regimes. The parabolic rate constant, kp (in gr2/cm4s) were 1.57 x 10-13 and 3.08 x 10-13 respectively for initial stage of oxidation then changed to-9 x 10-15 and-3 x 10-14 respectively for the remainder of the test. ASR measurement shows that the presence of Ti in the alloys decreases the electrical resistance up to 60%. Ti addition into Fe-Cr alloys affect the oxide growth rate and increase the conductivity of Cr2O3 scales.
Abstract: Foamed bitumen is a binder of cold mix road recycling materials. It is necessary to understand the best foamed bitumen properties prior to mixing with aggregate materials. Viscosity is one of the important properties, which facilitate the foam to distribute across the aggregate phase in the mixing process, and form a well coated asphalt mix. Unfortunately, the understanding of foamed bitumen viscosity and its contribution in the development of mixture performance is still poorly understood. This paper discusses foamed bitumen viscosity which was explored based on theoretical studies and a series of laboratory investigation. Foamed bitumen was produced using bitumen Pen 70/100 at temperature of 180°C. The research method was developed in three activities, i.e. (1) the previous studies on the foamed bitumen rheology, (2) investigating flow behavior of foamed bitumen, and (3) estimating foamed bitumen viscosity using Kraynik equation.The research results can be summarized in the following three points. First, foamed bitumen consists of gas content and liquid bitumen, in which the value of foam viscosity increases with the gas content. Second, foam flow can be used to indicate the apparent foam viscosity. Foamed bitumen with a higher foaming water content (FWC) tends to have a decreased flow rate and hence higher apparent viscosity. Third, foamed bitumen viscosity estimated using Kraynik equation is affected by gas content and liquid bitumen viscosity. It was found that an ERm of around 35 (or at FWC of 6%) is the critical area of foam viscosity.