Nanostructured Melt-Spun Sm(Co,Fe,Zr,B)7:5 Alloys for High-Temperature Magnets

High coercivity, the highest for Cu-free 2 : 17 Sm-Co ribbons, has been obtained in as-spun (= 211 kOe) and short time annealed (= 232 kOe) samples of Sm(CobalFe Zr B)7 5 alloys, with varying B, Zr, and Fe content (= 0-0 06, = 0-0 16, = 0 08-0 3) and wheel speed. In as-spun samples, the TbCu7 type structure and in annealed samples the Th2Zn17 and CaCu5 type structures is observed, plus fcc Co as minority phase is observed. Reduced remanence () is higher than 0.7. High-temperature magnetic measurements show very good stability above 300 C with coercive field as high as 5.2 kOe at 330 C. For annealed Sm(CobalFe0 3Zr0 02B0 04)7 5, very good loop squareness and high maximum energy product of 10.7 MGOe have been obtained. Increasing Zr content results in less uniform microstructure of annealed ribbons.Comment: IEEE Transactions on Magnetics, Vol. 39, No. 5, pages 2869 - 2871, September 200

) 7.5 Compound Institute of Nuclear Technology and Radiation Protection, NCSR "Demokritos

Abstract The present research work is focused on the effect of activation procedure on the hydrogen absorption-desorption properties of new rare earth -transition metal compound based on Sm(Co 0.6 Fe 0.2 Zr 0.16 B 0.04 ) 7.5 composition. Crystal structure and composition is always connected to the maximum capacity of the intermetallic hydrides. For composite materials the thermodynamic properties of hydrogenation -dehydrogenation procedure are mostly explained through microstructuremicrochemistry characteristics. Efficient hydrogen storage is direct connected to the desorbed hydrogen amount. The as hydrogenated material Sm(Co 0.6 Fe 0.2 Zr 0.16 B 0.04 ) 7.5 seems to have in the desorption a pressure plateau below the atmospheric pressure at room temperature while the absorbed hydrogen almost remains in the material having capacity of ~0.8 wt. % at 0.1 MPa -30°C. After the proper activation procedure, the hydrogenated material desorbs very high amount of hydrogen ~1.9 wt. % at 0.1 MPa -100°C. Subsequently, the treatment of the composite materials before hydrogenation-dehydrogenation procedures could play a crucial role on the efficiency

Electric Car Chassis for Shell Eco Marathon Competition: Design, Modelling and Finite Element Analysis

The increasing demand for energy efficient electric cars, in the automotive sector, entails the need for improvement of their structures, especially the chassis, because of its multifaceted role on the vehicle dynamic behaviour. The major criteria for the development of electric car chassis are the stiffness and strength enhancement subject to mass reduction as well as cost and time elimination. Towards this direction, this work indicates an integrated methodology of developing an electric car chassis considering the modeling and simulation concurrently. The chassis has been designed in compliance with the regulations of Shell Eco Marathon competition. This methodology is implemented both by the use of our chassis load calculator (CLC) model, which automatically calculates the total loads applied on the vehicle’s chassis and by the determination of a worst case stress scenario. Under this extreme stress scenario, the model’s output was evaluated for the chassis design and the FEA method was performed by the pre-processor ANSA and the solver Ansys. This method could be characterized as an accurate ultrafast and cost-efficient method

Lightweight Design and Welding Manufacturing of a Hydrogen Fuel Cell Powered Car’s Chassis

The development of the chassis for the hydrogen fuel cell powered car has been involved in the designing and manufacturing aspects, while taking into consideration the mass, strength, stiffness, centre of gravity (COG), and manufacturing cost requirements. Towards this direction, a chassis design is proposed employing a space frame structure and constructed by an aluminium alloy with great strength. The structural design has been derived through the lightweight engineering approaches in conjunction with the part consolidation, Design for Assembly (DFA) and Design for Manufacture methods. Moreover, it has been performed in compliance with the safety regulations of the Shell Eco Marathon racing competition. The material’s principal characteristics are the great strength, the low mass, as well as the great workability, machinability, and weldability. Following the national and global environmental issues, the recyclable characteristics of the aluminium alloy are an extra asset. Furthermore, the existence of aluminium alloy manufacturers around the fabricating area provides low cost supply and fast delivery benefits. The integration of the fuel cell powered vehicle is obtained through the designing and the manufacturing processes of the chassis and the parts fitted on the chassis. The manufacturing procedures are described thoroughly; mainly consisting of the cutting and welding processes and the assembling of the parts that are fitted on the chassis. Additionally, the proper welding parameters for the custom chassis design are investigated and are selected after deductive reasoning. The quality control of the weld joints is conducted by non-destructive methods (NDT) ensuring the required structural properties of the welds. A combination of the selected material, the specific type of the chassis, and the manufacturing processes lead to construction simplicity in a low manufacturing cost by using the existing laboratory equipment. Furthermore, the designing and manufacturing parameters lead to a stiff with a low centre of gravity, and the most lightweight chassis of the urban concept category at the Shell Eco Marathon race

Investigating Thermal Performance of Residential Buildings in Marmari Region, South Evia, Greece

In recent decades, the steady increase of energy consumption from building construction and operations cause atmospheric pollution and significant financial burden, mainly due to the high costs imposed from energy production. This study examines ways under which modern designs of a building can be applied on construction and domestication while following conventional methods of construction, compared to a building that has been constructed and domesticated under bioclimatic architecture. Particularly, two buildings were investigated in terms of the energy consumption incurred, being built on the same seaside area and period of construction and at adjacent plots of the same distance from sea for ease of comparison. The first building (A1) was constructed under the principles of bioclimatic architecture, being also facilitated with green and smart technologies. The second building (A2) was constructed under conventional construction techniques. The energy efficiency of both buildings was calculated by the “TEE KENAK” software, while specific parameters were recorded. Energy classifications of both buildings were valued and a proposed scenario and interventions unveiled the energy classification upgrading from A2 to A1. Our analysis revealed, as also found in the literature, that during thermal energy oscillating conditions, corresponding relative humidity stresses were observed, indicating that the vapor pressure handling should be taken into account towards comfort. The preliminary incremental cost evaluation and comparison of A1 and A2 energy upgrading under the criterion of simple payback period were critically discussed