Materials Science Forum Vol. 1005

Abstract: Mechanical alloying has recently attracted considerable attention as researchers try to improve materials properties. The process can be performed at room temperature and homogeneous alloys can be produced. In this work Fe–28 wt. % Al; Fe–26 wt. % Al–2 wt. % Sn and Fe–26 wt. % Al–2 wt. % V alloys were synthesized by mechanical alloying to investigate the effects of tin and vanadium additions on the structural and microstructural properties of Nanocrystalline FeAl Alloy. Fe₇₂Al₂₈, Fe₇₂Al₂₆Sn₂ and Fe₇₂Al₂₆Sn₂ were ball milled for 30 h under argon atmosphere using a rotating speed of 200 rpm with 15 min pause time after every 15 min running time. The structural and microstructural properties of the ball milled powders were analyzed using X-ray diffraction (DRX) and Mössbauer spectroscopy techniques. The final powders are characterized by an average crystallite size of 10 nm for the Fe₇₂Al₂₈ alloy, 6 nm for the Fe₇₂Al₂₆Sn₂ alloy and 19 nm for the Fe₇₂Al₂₆V₂, accompanied by the introduction of a lattice strain of order of 1.55 %, 0.78 % and 0.80% respectively. The Mossbauer study of the Fe₇₂Al₂₆V₂ samples showed doublet with isomer shift IS= 0.17 mm/s and three magnetically split sextet.

Abstract: Peritectic transformation contraction of ferrite to austenite plays an important role in the formation of cracks for steels. In order to evaluate the peritectic transformation contraction of steels at the initial solidification, the solidification of 304 stainless steel under different cooling rates were carried out by using high temperature laser confocal microscopy, and then the surface roughness and peritectic transformation contraction were analysed in combination with the microstructure of solidified steel. The result shows that the solidification model of 304 stainless steel was ferrite-austenite model in the experiments, and peritectic transformation occurred during solidification. The residual ferrite in the as-cast structure were vermicular, skeletal and reticular in turn with the increase of cooling rate. The volume contraction caused by peritectic transformation resulted in wrinkles (surface roughness) appearing on the grain surface. The peritectic transformation contraction that was affected by surface roughness increased first and then decreased with cooling rate increasing, indicating the peritectic transformation contraction can be evaluated by the surface roughness.

Abstract: In order to study the tribological properties of titanium alloy materials and reinforced PTFE pairs treated by surface nitriding modification in seawater environment under low speed and high load, the physical properties of surface nitriding modified treatment were observed and measured with Ti-6Al-4V ELI as the substrate, and the samples of substrate and surface nitriding were modified as disks to 25% fiberglass , 15% glass fiber +5% graphite and 60% tin bronze reinforced PTFE as distribution pins, the friction properties of substrate and surface nitriding modification layer in seawater environment were studied by friction tester. The results show that the friction coefficient between titanium alloy and auxiliary pair is above 0.1, the friction coefficient of titanium alloy surface treatment specimen is lower than that of TC4 titanium alloy, the wear of surface nitriding modified treatment sample is significantly slight, the friction coefficient of 60% tin bronze distribution is the highest, and the friction coefficient of 15% fiberglass +5% graphite is about 15% higher.

Abstract: TC4 titanium alloy was treated by ion nitriding. The structure of nitriding layer was analyzed by scanning electron microscopy. The depth and microhardness of nitriding layer were measured. The frictional properties of titanium alloy before and after nitriding were compared by friction test. The results show that the ion nitriding technology can form a stable nitriding layer with a depth of up to 20μm and a surface hardness of 560 HV0.2. At the same time, after nitriding, the wear resistance of the titanium alloy surface is improved. And the coefficient of friction between the friction pair is reduced.

Abstract: This paper discusses the performance of locally made porous paving that has been applied in West Bandung, Indonesia, for almost one year. The porous paving uses fly ash and bottom ash produced by a local coal mining industry to minimize the use of cement and to reuse the industry’s waste. The porous properties of the paving corresponds substantially to the context of the high yearly rainfall in the tropical region up to 442 mm³ and to the high terrain of Lembang in 1080 meters above sea level which is best to immediately recharge ground water. In this paper, the paving’s performance is assessed for its role as a landscape architecture element by applying Vitruvius’ design theories of beauty: firmitas (by the ability to maintain shape or strength), utilitas (by its ability to infiltrate water) and venustas (by its physical appearance or signs of deterioration). The results show that the porous fly-ash paving demonstrate environmentally landscape architectural element. It will significantly contribute to the degrading quality of spatially dense urban environment of Bandung

Abstract: At present, fiber reinforced composite materials (FRP) are widely used in the reinforcement of concrete structures. The bonding interface between FRP plates and concrete is the key part of the strengthening of concrete structures with FRP plates. The bonding performance directly determines the success or failure of structural reinforcement. Based on the self-developed test device, the development of FRP and concrete in direct shear debonding test specimens, with the aid of advanced digital image correlation DIC technology, accurate measurement of specimen strain distribution on the surface of the FRP plate, and the FRP plate surface strain along the plate long distribution rule and the bond strength of the specimens was well researched, it reveals that the stripping of FRP and concrete interface failure process, and provides technical guidance for the treatment of FRP-concrete bond interface in practical projects.

Abstract: This study aims to develop the mix proportion of concrete incorporating water purification sludge (WPS), as parts of fine aggregate and consequently investigate its mechanical properties and durability. The experiments involve three sludges from Da-Nan, Lin-Nei and Nan-Hua water treatment plants in Taiwan. In addition to the control mixture without WPS, four replacement levels of 20%, 40%, 60% and 80% of fine aggregate were selected for preparing the concrete mixture. The concretes tested were designed to have three target compressive strengths of 14MPa, 18MPa and 21MPa. Test results show that the compressive strengths of the Da-Nan and Lin-Nei WPS concretes meet the design requirements, and the strength of the Nan-Hua WPS concrete is lower to be only suitable for application in low strength concretes. The shrinkage deformation of the Da-Nan and Lin-Nei WPS concretes increase with the increase of sludge replacement level, however, the shrinkage deformation decreases with the increase of the compressive strength of concrete. If the sludge replacement ratio is less than 40%, its effect on the compressive strength of the Da-Nan and Lin-Nei WPSs concrete is limited whether they are cured in water or in the air.

Abstract: This work focuses on the new alternatives and technological solutions of clay architecture design for contemporary individual houses in the Sahara Desert. Clay considered as a natural and eco-friendly building material, moreover is now back in the new project because of his ecological and aesthetic benefits that attract the attention of increasing numbers of architects. Current researches efforts focused on increasing its resistance in order to make it competitive and contemporary material. The main aim of this study is to share and disseminate technological and technical solutions besides the new possible alternatives to the architectural design of contemporary individual houses by using clay material. The research methodology went through different phases that range from analyzing the historical experience of clay construction in the Sahara Desert and investigation of the new ecological and technological alternatives. The clay is a lower-impact building material in terms of energy performance, recycle, resources consumption, low-cost, sustainability, and all these factors make the clay material as favourable and excellent natural and contemporary material. The use of clay material with new techniques and machines technologies is an environmental and economic alternative for contemporary individual houses in the Sahara Desert.

Abstract: In tropical regions such as the Philippines, pineapple leaf fiber (PALF) is abundantly available as a low-cost and renewable source for industrial purposes. In this research, PALF was used as a reinforcing material for cement-based composites to open up further possibilities in waste management. Since natural fibers are not fully compatible with the matrix due to their hydrophilic nature, surface treatment is necessary to enhance the fiber-matrix bonding. Fibers were treated using sodium hydroxide (NaOH) with varying concentrations (4%, 8% and 12%) for 6-hr immersion time at room temperature. PALF was then added at varying content (1%, 4% and 7% w/w cement) to the concrete mixture with a design mix ratio of 2:1 (sand: cement) and a constant water-cement ratio of 0.55. The samples were mechanically characterized after 28 curing days following ASTM C209 and ASTM C473. Full factorial experimental design (FFED) was used to investigate the effects of alkali treatment and the fiber content on the mechanical strengths of the composite. Experimental methods, analysis of variance (ANOVA) and normality test were carried out to evaluate, analyze and validate the results. The best results for tensile strength parallel to the surface and flexural strength at 2.028 MPa and 1.495 kN, respectively, were observed at composites with 1% PALF with 4% NaOH. Meanwhile, composites with 1% PALF with 12% NaOH showed the best result for tensile strength perpendicular to the surface at 1.681 MPa. According to ANOVA results, only the model for the tensile strength perpendicular to the surface showed a curvilinear behavior (p-value=0.012). Results revealed that the factor with the most significant effect was the interaction of the fiber content and alkali treatment on the tensile strength parallel to the surface (p-value=0.000), tensile strength perpendicular to the surface (p-value=0.001) and flexural strength (p-value=0.001).