Advanced Materials Research Vols. 264-265

Abstract: The application of simulation software packages for mould design and injection moulding process is becoming importance to optimizing the moulding quality and satisfy market needs. This paper presents the simulation of mould filling and packing for various polymer resin types. The filling and packing pressure phases for different type of polymer resins as well as the flow behaviour of molten resin in the mould cavity were investigated. Three common polymer resins which are amorphous and crystalline thermoplastics were used. Cylinder component cups with variation of wall thicknesses were designed. Two-cavity prototype moulds for cylindrical shape component were constructed by using AutoCAD 2006 including assembly and part drawings. The 3D model was produced by using Autodesk Inventor Professional. The result successfully revealed that polyamide resin required shorter time for filling the cavity and less pressure compared to PS and ABS.

Abstract: successful design of folding bicycle should take into account the function, material properties, and fabrication process. There are some other factors that should be considered in anticipating the behavior of materials for folding bicycle. In order to understand the relationship between material properties and design of a folding bicycle and also for the future direction in new materials with new design, a comprehensive study on the design under different conditions are essential. Therefore, a systematic study on the relationship between material properties and design for folding bicycle has been performed. The advantages and disadvantages matrix between conventional bicycle and folding bicycle is presented for better understanding of the materials properties and design. It was found that the materials properties of the folding bicycle frame such as fatigue and tensile strength are the important properties for the better performance of the frame. The relationship between materials properties and design is not straight forward because the behavior of the material in the finished product could be different from that of the raw material. The swing hinge technique could be a better technique in the design for the folding bicycle frame.

Abstract: Magnesium sacrificial anodes are widely used in cathodic protection systems. In the present work, samples of Mg-0.7% Mn- x% Al- y% Ti (x,y = 0-0.6) alloys were electrochemically characterized to evaluate their performance as magnesium sacrificial anodes. The experiments focused on the influence of aluminium and titanium contents on the electrochemical behavior and efficiency of anodes. Aluminium and titanium was used in different concentrations ranging from 0.15 to 0.60 at.%. Short-term electrochemical tests, ASTM G97-89, as well as polarization curves were performed to obtain electrochemical behavior and efficiency and to reveal any tendencies to be passive. It is shown that by increasing titanium content an improvement of electrochemical properties of magnesium anode such as current capacity and electrochemical efficiency can be obtained.

Abstract: The experiments focused on the influence of strontium and calcium as additional alloying elements on the grain size and phase distribution of AZ91 magnesium alloys. For this purpose, different concentrations of Sr (0.01, 0.1, 0.4, and 0.8) and Ca (0.01, 0.1, 0.4, 0.6 and 0.78) were added. The microsturctural examination of specimens was made by an optical microscope and scanning electron microscope. From obtained results it was found that using 0.4 wt% strontium can provide a fine and uniform structure.

Abstract: La substituted barium hexaferrite Ba1-yFe12LayO19 with 0≤ y ≤0.5 was synthesized by chemical co-precipitation method using aqueous solutions of metallic chlorides at ambient temperature. NaOH was used as a precipitant. The co-precipitated products were annealed at 900 and 1000°C. The effects of La addition on the phase composition, morphology and thermal behavior of samples were studied using XRD, SEM and DTA/TGA, respectively. XRD results indicated that barium hexaferrite forms together with some intermediate phases in samples annealed at 900°C and the amount of intermediate phases decreased significantly by increasing annealing temperature to 1000°C. XRD results also showed that in sample annealed at 1000°C, the crystallite size of magnetic phase decreases from 98 to 64 nm by increasing the amount of La. Thermal analysis (DTA/TGA) implies that formation temperature of barium hexaferrite is increased with addition of La.

Abstract: Iron sand deposit in Indonesia generally consisted of titanomagnetite with ilmenite lamelaa occurred in magnetite particle structure, therefore direct physical separation through magnetic method at particle size of 400 mesh only capable increasing total iron content up to 60%. In order to increase the grade of iron, decreasing TiO2 content in iron sand was applied by chemical method of alkaline fusion followed by grinding to 100 mesh and magnetic separation. Pre-oxidation was conducted prior to reduction and alkaline flux was added to coal based reduction system of in a rotary kiln. The alkali addition into the reduction system resulted to the formation of metallic iron and non metallic phases, in which sodium titanate compounds as nonmagnetic product can be separated from calcine using separator magnetic. XRD analyses of the concentrate and tailing as magnetic separation products showed concentrate was dominated by metallic phase compared to oxide phase and it doesn’t consisted iron-titan oxide and iron oxide. On the other hand, tailing was consisted iron-titan oxide and iron oxide.

Abstract: Production of tungsten-copper composites includes compaction and sintering of tungsten powder, then infiltration of copper melt within the tungsten skeleton. Sintering of tungsten compacts usually requires a temperature range of 1800 to 2200°C. This means, this process not only needs advanced heating equipments and high expenses but also may cause formation of defects such as structural heterogeneities, cracks and distortions. In this research the required sintering temperature was reduced to 1500°C by increasing compaction pressure. Also the relation between compaction pressure applied through a cold isostatic press (CIP), and green density of the compacted tungsten powder was established. In addition, the effect of various pressures on densification of tungsten compacts during sintering at moderate temperature, i.e. 1500°C was studied, and the optimum structure for infiltration was chosen. Then by infiltrating Cu melt into the optimized W-skeleton, composites of W-Cu having a density of 17.2 gr/cm3 were produced. This method of production provides an innovative technique for obtaining a desired density of infiltrable skeleton, sinterable at a lower temperature than the temperatures used for the conventionally packed W-compacts without introducing structural inhomogeneities during sintering. Study of some characteristics of the optimized composite produced by the above technique satisfied the requirements for production of W-Cu composites having all the specifications given for these types of composites produced at higher temperatures than 1500°C.

Abstract: In this work, in order to predict the forming failure of AZ31 magnesium alloy sheet in drawing process at elevated temperatures, a series of square cup tests at various temperatures and FE analyses were carried out. The critical damage values and the mechanical properties dependent on strain rates and temperatures were evaluated from uniaxial tensile tests and those were utilized to the forming failure prediction using FE analysis. Based on the plastic deformation history obtained from FE analysis and Cockcroft and Latham’s ductile fracture criterion, the fracture initiation time and location were predicted and verified with the experimental results.

Abstract: In Malaysia, especially Borneo Island Sarawak has a large scale of tropical wood species. In this study, selected raw tropical wood species namely Artocarpus Elasticus, Artocarpus Rigidus, Xylopia Spp, Koompassia Malaccensis and Eugenia Spp were chemically treated with sodium meta periodate to convert them into wood polymer composites. Manufactured wood polymer composites were characterized using mechanical testing (modulus of elasticity (MOE), modulus of rupture (MOR), static Young’s modulus) and decay resistance test. Modulus of elasticity and modulus of rupture were calculated using three point bending test. Static Young’s modulus and decay resistance were calculated using compression parallel to gain test and natural laboratory decay test respectively. The manufactured wood polymer composites yielded higher modulus of elasticity, modulus of rupture and static Young’s modulus. Wood polymer composite had high resistant to decay exposure, while Eugenia Spp wood polymer composite had highly resistant compared to the other ones.

Abstract: This experimental research work attempted to use End milling on Machinable Glass Ceramic (MGC) using micro grain solid carbide end mill under dry conditions. The predictive Surface Roughness model has been developed in terms of Spindle speed, Feed rate and axial depth of cut by Response Surface Methodology (RSM). The influence of each milling parameter analyzed and results showed that axial depth of cut was the most dominant variable. The adequacy of the model has been verified by ANOVA.