Advanced Materials Research Vols. 383-390

Abstract: The bulk mass concrete pier is esay to crack because of higher temperature contrast between inner and outer of concrete. Experimentation use admixtures to replace some of cement so as to low the hydration heat. Fly ash can decrease more hydration heat than granulated blast furnace slag. If 40 percent of cement in weight is replaced by same amount of blend admixture of fly ash and granulated blast furnace slag, not only the compression strength can meet the requirement of engineering design, but also the hydration heat reduce a lot. Meanwhile, this paper develops a novel lining fabric especially for concrete steel formwork to advance water-retaining property and warm-keeping efficiency, and to distract shrinkage stress by ways of veins of fabric. Because of developed lining fabric and optimized mixture in this paper, the cracking problem of bulk mass concrete pier is avoided.

Abstract: Based on the limit analysis equilibrium theory for the soft soil foundation under rock filling load, a new blasting technique is developed on the main mechanism to soften the strength of soft silt and to relieve the inside pressure of different kinds of soft soil, and a set of design method of blasting destressing is proposed to replace soft silt by rock filling. This technique is applied in the rock filling embankment of a waterfront airport project, which makes a breakthrough to the designed application limit of the current technical codes and acquires a favorable effect of replacement by rock filling.

Abstract: Lost Foam Casting, pressurized casting, solidification, mechanical properties. Abstract. The paper presents the result of investigation on aluminum-silicon (LM6) alloy cast using pressurized lost foam casting process. The study investigated the effect of pressure and sand size on hardness and roughness of the casting produced. Air pressure of 1, 2, 3 and 4 bars was applied on the solidifying alloy poured in mould of sand sized 40-60(AFS). The roughness and hardness of the casting was measured using Hobson (Surtronic 3+) and Vickers hardness testing machine respectively and reported in the average of ten readings. For roughness measurement of the solidified castings, measurement was conducted in 25mm run whilst 11kgf was applied for Vickers hardness indentation test. The results show that using of finer sand size besides applying pressure during solidification of LM6 alloy has significant influence on roughness and hardness of the alloy. Increasing the applied pressure and used of fine sand size expedited heat transfer from the melt to the mould and surrounding thus decreasing solidification time. Consequently, reduced casting surface roughness as well as increased in hardness.

Abstract: This study aims to investigate the formation behavior of intermetallic phases on casting mold die and its effect on erosion tendency in molten Al-Si alloy with the variation of Fe content. For these purposes, dipping tests of die material into molten Al-Si alloys with 0.98 and 1.33wt%Fe were carried out as a function of dipping time. Three kinds of intermetallic phases, α-AlFeSi, β-AlFeSi and θ-AlFe, were found to form on the interface between die and molten alloy in sequence, as iron and aluminum solutes diffuse into the molten alloy and die steel, respectively. It was discussed that the erosion process was decelerated in the case of the high-iron containing alloy, because of the decreased gradient of iron solute through the interface and enhanced diffusion barrier of intermetallic layer.

Abstract: Rapid solidification processing is a technique used for refining the primary silicon and seems to be the most promising technique for the production of high Si Al-Si alloys (i.e. Si content greater than 17 wt.%). There are number of routes which can be used to produce rapid solidification, including spray methods, weld methods, and chill methods. Of these, melt spinning is the most widely used industrially due to its high cooling rate and the ability to process large volumes of materials. This paper summarizes melt spinning and rapid solidification, highlighting a potential production route for aluminium-high silicon alloys involving melt spinning followed by hot isostatic processing.

Abstract: Zeolite membranes were successfully synthesized from coal fly ash by hydrothermal treatment onto 10-cm-long tubular porous supports. The membranes were characterized from XRD analysis, SEM observation and the pervaporation performance. Under the optimized conditions, LTA-type membrane from coal fly ash showed fairly efficient for the dehydration of organic liquids. The maximum selectivity reached more than 3000 with accompanying flux as high as 3.0 kg/(m²•h) for separation of 90 wt% EtOH aqueous solution at 75 °C.

Abstract: A growing demand for lightweight products has been brought about by the rapid development of new automobiles in order to reduce fuel consumption, since the global environment conservation meeting at Kyoto. One of the keys to reduced fuel consumption is to utilize high-strength, light materials like stainless-steel, high-tensile strength steels and magnesium alloys, which are difficult to form due to their material characteristics compared to normal steel tubes. The purpose of this paper discuses the development of our new pressing technology that forms a relatively high-strength and light weight stainless-steel tube which is SUS436 with surface screw threads. Our new press-forming process was tested in order to obtain accurate screw threads on stainless-steel tubes. Finite element simulation and a 3-D digitizer were used to measure the accuracy of tubes manufactured by the proposed pressing method. It was proved from FEM simulation and a 3-D digitizer measurement that the proposed press-forming method decrease tube thickness more effectively than conventional roll-forming technology. As a result, the maximum decrease in material thickness produced by conventional roll-forming process was 40%, but the maximum decrease in material thickness produced by our press-forming process was 20%. Especially the processing by four outer dies and two inner dies is better as for material thickness than the processing by six outer dies and three inner dies.

Abstract: This paper presents effects of silicon carbide (SiC) powder in dielectric fluid of micro EDM on material removal rate (MRR). The aim is to identify the optimum level of SiC powder concentration and other micro EDM parameter for higher MRR. The work material was titanium alloy (Ti-6Al-4V) machined with tungsten carbide (WC) electrode by varying two machining parameters SiC powder concentrations and discharge energy. By using two factor four level factorial design of experiment, sixteen experiments were conducted. Data were analyzed by Design Expert® software. In this experimental investigation, maximum MRR of 7.3 µg/min was obtained for 24.75 g/l SiC powder concentration and 56.77 µJ discharge energy. The analysis of variance revealed that the SiC powder concentration in dielectric fluid on micro EDM has significant influence on MRR Ti-6Al-4V titanium alloy.

Abstract: This Abrasive Water Jet Machining (AWJM) process is usually used to through cut materials which are difficult to cut by conventional machining processes. This process may also be used for controlled depth milling (CDM) of materials. This work primarily focuses on controlling the abrasive flow rate to reduce the time for machining the component. Here, an experimental setup is made with a modified attachment for abrasive feed system to machine for Ti-6Al-4V alloy. The work also investigates the surface morphology, tolerance on depth of machining and surface waviness for the modified setup. With change in mass flow rate of abrasive, the traverse speed is altered and its effects on the machining time are studied. It is observed that traverse speed is an important parameter in the case of CDM for AWJM. It is also shown that surface waviness can be reduced as traverse speed is increased by using modified abrasive feeding system.

Abstract: Investigation of the cutting tool failure is one of the important factors in order to optimize the cutting parameters. This paper studies the cutting tool stresses (maximum principal, maximum shear and von Mises) at the shank and at the tip using three failure theories. These stresses are analyzed by means of the finite element method using MSC patran/nastran software and the experimental method using electrical-resistance strain gages. The comparison of the stresses obtained from these two methods for different feed rates and different rotation speeds are depicted in figures.