Abstract: Geopolymers can be transformed into ceramics upon sintering. This paper reports the effect of temperature on the physical, mechanical properties and characteristics of kaolin geopolymer ceramic. The nepheline ceramic was fabricated through geopolymerization. The geopolymer samples were exposed to temperature from 900 °C up to 1200 °C. Kaolin geopolymer undergo shrinkage upon temperature exposure. Unheated kaolin geopolymer appeared to be amorphous and crystalline nepheline was the major phase after sintered to high temperatures as depicted by XRD analysis. Microstructural analysis showed formation of denser structure as the temperature increased. The maximum flexural strength of 86 MPa is achieved at temperatures of 1200 °C.
Abstract: This study focuses on the analysis of plastic injection moulding process simulation using Autodesk Moldflow Insight (AMI) software in order to minimize shrinkage by optimizing the process parameters. Two types of gates which is single and dual gates have been analysed. Nessei NEX 1000 injection moulding machine and P20 mould material details are incorporated in this study on top of Acrylonitrile Butadiene Styrene (ABS) as a moulded thermoplastic material. Coolant inlet temperature, melt temperature, packing pressure and cooling time are selected as a variable parameter. Design Expert software is obtained as a medium for analysis and optimisation to minimize the shrinkage. The polynomial models are obtained using Design of Experiment (DOE) integrated with RSM Center Composite Design (CCD) method in this study. The results show that packing pressure is a main factor that contributed to shrinkage followed by coolant inlet temperature, while melt temperature and cooling time has less significant for both single and dual gates. Meanwhile, single gate shows a better result of shrinkage compared to the dual gates.
Abstract: Rejected due to Ethics and Copyright issue
Abstract: Warpage is a common issue in an injection moulding process due to non-uniform temperature variation causing differential shrinkage on the moulded parts. In designing moulds for injection molding process, it is very difficult to achieve efficient cooling with uniform thermal distribution. Most of researchers focus on an optimisation of processing parameters to improve the warpage. However, the conformal cooling channels have advantages with the uniform distance between center of cooling channels and mould surfaces in order to get a better thermal distribution thus reducing the warpage. This paper presents the Milled Grooved Square Shape (MGSS) conformal cooling channels which provide more uniform in cooling and have a bigger effective cooling surface area cross sectional area and comparing to circular and others type of cooling channels with similar cross section. A case study on front panel housing is investigated and the possibility of fabrication the conformal cooling channels on hard tooling for injection moulding process which is easier to design, fabricate and assemble compared to other method are presented. The performance designs of straight drilled are compared to the two types of MGSS conformal cooling channels by using Autodesk Moldflow Insight (AMI) 2012. The analyses show that the both types of MGSS conformal cooling channel suggested can provide a more uniform thermal distribution and able to reduce the warpage on the molded part compared to the straight drilled cooling channels.
Abstract: Utilization of lignocellulosic biomass as the source for lignin could possibly gain an interest and future demands due to its potential to be converted into high value added compound based on their structural characteristics. Three types of biomass lignin originated from oil palm empty fruit bunch fiber (OPEFB), coconut husk and kenaf fibers are subjected to an alkaline hydrolyzation in steam autoclave and precipitation by phosphoric acid. The structural characterization of all three lignin samples performed by FTIR spectroscopy and HNMR analysis suggests that OPEFB is primarily consist of syringyl (S) units while coconut husk and kenaf fiber were consisted of guaiacyl (G) units. However, all three samples exhibit small portion of p-hydroxyphenyl propane (H) units.
Abstract: The serious quality problem in the magnetic substrate during polishing process by using conventional lapping machine had generate the idea to develop a doubled-sided lapping machine of polishing stone manufactured of an abrasive and resin. After certain parameter of polishing process, the polishing stone starts to clog because of debris agglomeration from the polishing substrate, thus lead to the scratches on the magnetic substrate which will affect its performance. Three difference type of acid were used as to dissolve the debris agglomeration in the polishing stone. The influence of oxalic, phosphoric and citric acid at three different times were examined. It was found that oxalic acid is the best chelating agent in dissolving the debris in the polishing stone.
Abstract: A comprehensive study was carried out to assess the effectiveness of untreated and treated palm kernel shell (PKS) as filler into the polypropylene (PP) matrix at different filler loading (5 wt%, 10wt%, 15wt%, 20wt%, and 25wt%) to form a biocomposite material. Surface modification of PKS surface was made by treating it with 2wt% of 3-aminopropyltriethoxysilane (APTES) coupling agent. The efficiency of treated PKS and non-treated PKS were assessed based on its tensile and flexural properties, water absorbability, and surface morphology. The biocomposites were prepared using Brabender Plastograph internal mixer at processing temperature of 180°C and rotor speed of 60rpm. Results showed that the treated PKS/PP has better mechanical properties with less water absorption than non-treated PKS/PP and neat PP. Moreover, the scanning electron microscope (SEM) surface images of the treated PKS/PP biocomposites showed stronger interaction between filler and matrix due to surface modification. The Fourier transmission infrared spectroscopy (FTIR) results showed the changes in the functional groups of the treated PKS indicating an effective surface modification using amino silane. It was concluded that the addition of amino silane treated palm kernel shell as filler/additives into PP matrix offers better properties on tensile, flexural and water absorbility of the biocomposites.
Abstract: The applications of stainless steels may be meeting in chemical industry, food industry, civil building, but present an increased interest also in machine constructions or household.This paper highlight the structural modifications obtained after temperature variations for AISI 321 stainless steel. The modifications of structure and proprieties can be induced by heat treatments applied to semi-products before or after the obtaining of final parts, but also by heating at regimes which respect the exploitation conditions of part. In the experiments, it is applied quenching to put into solution, with modification of final treatment temperature and maintaining time, aiming the dissolution of complex carbides and in this mode an easy processing. The treatment parameters were chosen, after the determination of alloying elements by AISI 321 samples, by optic spectrometry. The dilatometric analysis aimed to highlight the structural modifications, specific to thermal fatigue phenomenon, due to temperatures variations.
Abstract: The paper present theoretical and practical aspects concerning to the phenomena of thermal / mechanical fatigue specific to metallic materials, which are found in the structure of industrial parts, subjected to thermal and mechanical requests, also in combination with the corrosion phenomenon, pressure different etc. The analyzed alloys subjected to thermal and mechanical fatigue requests, on a prototype testing installation, using samples from Cu-Zn-Al alloys, which have been processed at standard dimensions by machining. Function of chemical composition of alloy, after a variable number of cycles it was found the micro-cracks appearance that generates crack and finally the break of samples. The SEM realized at different magnifications, highlight the character of samples break.
Abstract: Increase the life exploitation of implants has been the motor factor in the elaboration of the new biocompatible alloys based on cobalt. The paper aims the complete structural characterizations for CoCrMoSi6 alloy, based on modern investigation methods, like compositional analysis by EDX method, optical and electronic microscopy analysis, X-ray diffractrometric analysis, fracture analysis. The experiments aimed to establish all the structural aspects for CoCrMoSi6 alloy and his recommendation for using to manufacture the components for medical applications. The results obtained from the SEM microstructural analysis, for the original version allied with silicon in percentage of 6%, certify a dendritic structure specific to the cobalt base alloys. This paper established the structural aspects for a new variant of CoCrMoSi6 alloy and recommends their use successfully in the production of components for medical applications.