Papers by Keyword: Solid-State

Abstract: Optimizing the performance and reliability of welding techniques for dissimilar aluminum (Al) to titanium (Ti) is a promising way to establish new applications in aerospace industry. Due to structural weight reduction, lightweight materials can help to minimize fuel consumption and save emissions. Solid-state welding technologies allow short joining cycles and metallurgical changes, residual stresses and severe intermetallic compound formation can be reduced by limited thermal exposure. Besides temperature and plastic deformation, intimate contact plays an important role for diffusion. In this work, AlMgSi alloys with systematic variations of Mg and Si alloying elements, were welded to Ti6Al4V (Ti64) by refill Friction Stir Spot Welding. The focus lays on the effect of Ti64 sheet surface roughness, varied by different surface preparations. Additionally, the influence of the plunge depth, the distance between the tool and the Ti64 sheet surface is analyzed. It was found that a reduced tool to interface spacing has a beneficial influence on joint integrity. Grinding trenches allowed better bonding compared to the pit-like surface structure generated by sandblasting, which led to an increase in mechanical lap-shear properties. Knurling the grinded surfaces resulted in high standard deviation, as most likely not the whole interface area was bonded. However, the partially outstanding properties showed that a beneficial effect can be expected due to mechanical interlocking mechanisms, when sufficient diffusion is ensured.

Abstract: Optimizing the mechanical properties of aluminum to titanium welds is crucial to establish applications for dissimilar lightweight structures in the aerospace industry. In this context, solid-state welding technologies have proven effective in terms of short joining cycles, allowing the combination of cost-effective production and structural weight optimization. However, metallurgical effects between aluminum and titanium in the joint interface are still not completely understood due to differences in physical as well as chemical characteristics. In this study, aluminum alloy 6013 was welded to Ti6Al4V by refill Friction Stir Spot Wel ding, including systematic variations of Mg and Si alloying element content in the used AA6013 sheets. In total five different Al alloys were welded to the titanium to investigate the influence of Mg and Si during processing. Apart from the material selection, the weld strength is mainly influenced by the intermetallic compound thickness at the interface, which in turn primarily depends on the exposed temperature cycle. Consequently, major interest during this study was given on the temperature evolution, interfacial features and the global mechanical properties.

Abstract: Battery technology applications for energy storage are currently increasing. The most popular kind of battery in use today is the lithium-ion battery. However, lithium is limited. In fact, the need for batteries as energy storage devices grows over time. One alternative for replacing lithium-ion batteries is the sodium-ion battery because its characteristics are similar to lithium’s and it is very abundant. In this study, Na-NCM 532 has been successfully produced using a co-precipitation and solid-state method combination. The co-precipitation process, using oxalic acid as a precipitation agent and ammonia as a pH adjustor, can be used to create sodium ion-based cathode materials. It is clear from the characterization that the material has been formed and has a good structure. A hexagonally layered material structure can be seen in the XRD patterns. FTIR analysis revealed that the material was produced after the sintering process. The morphology of the substance, which has dimensions between 1 to 5 micrometers, was revealed by a SEM investigation. The EIS test results show a battery conductivity of 1.24 x 10^-4 Scm^-1_. The electrochemical performance of the Na-NCM 532 cathode sodium battery and hard carbon anode was evaluated in a type 18650 cylindrical cell. The sodium battery was tested at a voltage window of 1.5-3.7 V and a current of 0.05C produced a capacity of 40 mAhg^-1.

Abstract: In this study we have synthesized the iron and bismuth co-substituted BaTiO₃ ceramic, with the general formula: Ba_0.95Bi_0.05Ti_1-xFe_xO₃ for x=0.00 to 1.00, by solid state route. The impedance and electrical properties of these materials were investigated. The dispersion in conductivity in these ceramics can be described by Jonscher's power law and suggests a mechanism of conduction that is related to the Correlated Barrier Jump (CBH) model, according to which charge transport occurs between localized states due to a jump of the potential barriers. The conductivity results confirmed the semi-conductor behavior of these ceramics at high frequency region. The Nyquist plots for the different ceramics confirmed the simple electrical relaxation phenomena with the presence of a Debye-type relaxation phenomenon for x<040 of Fe content. While above this rete, the relaxation behavior is transformed into a Non-Debye phenomenon.

Abstract: So far, there has been a large number of high conductivity of solid materials to replace the liquid electrolyte. All solid-state composite polymer electrolyte materials have not yet fully realized industrial production, but many areas are moving in the direction of practical development. With the deepening of the study, the ionic conductivity mechanism and constantly improve, but the ionic conductivity of composite electrolytes should be improved, need to conduct groundbreaking research in the preparation process, structure and properties of the composite electrolyte materials have many problems. The composite polymer electrolyte materials has become an intersection of many disciplines including materials science, chemistry, physics, and the content may lead to the field of new energy materials, in particular, is a new technological revolution in the field of battery materials, which study of the problem will continue and in-depth.

Abstract: Solid-state photocycloaddition reactions between tri-2-pyrones (1a,1b) with benzophenone (2) gave the corresponding oxetane derivatives (3a:3a′=1:1 and 3b:3b′=1:1, 1:2 adducts) with high site- and regioselectivity across the C5-C6 , C5′-C6′ and C5′′-C6′′ double bonds in 1 via the triplet excited state of 2. The site- and regioselectivities were explained by MO calculations. The hydrogen-bonding interaction between 2 and 1a, 1b and the triplet reaction mechanism were also explained by the IR analyses and the quenching experiments, respectively.

Abstract: Magnesium oxide (MgO) is a metal oxide which has many applications in industry and can be synthesized by many different synthesis methods. In this study, MgO was synthesized by using two different methods which were sol-gel and solid-state reaction methods. Both samples were annealed at 800 oC for 24 hours and characterized by using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The band gap energies for both samples were determined by using UV-Vis NIR Spectroscopy. The band gap values of the samples are evaluated from the data. It was found that the band gap energies of the MgO using different synthesis route were not the same.

Abstract: The properties of polymer/semiconducting nanoparticle (NP) composites-materials used in hybrid, bulk-heterojunction photovoltaic materials-are dependent on the interaction of the NPs and polymer. Composite films of water soluble polymers and CdS NPs have been produced both by synthesizing the NPs within the polymer matrix and by adding the CdS NPs, containing a capping agent, to the polymer. The composites have been characterized by microscopy as well as 1H, 13C and 113Cd solid-state NMR. When synthesizing the NPs within the polymer, the polymer matrix plays a role in the cadmium sulfide NP nucleation, growth and structure. In the blended system, the dominant interaction between the glycerol capping agent and sulfonated polymer is observed to be hydrogen bonding.