Materials Development (United States)

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A decentralised distributed ledger system called Blockchain Technology (BCT) enables safe, open, and impenetrable transactions without the need for a central authority. The technology was initially created for the Bitcoin cryptocurrency, but it has subsequently been applied to other areas such as voting procedures, supply chain management, and digital identity management. The technology is increasingly becoming accepted in the academic setting for a variety of purposes, including the creation and storage of academic records. There are numerous platforms accessible for this usage, though. When numerous decision-makers are engaged in the selection process, picking an appropriate platform can be a contentious affair. For decision makers, selecting among a wide range of acceptable options might be difficult. It is possible to overcome these difficulties by using Multi-criteria Decision-Making (MCDM) techniques. When there are numerous elements to take into account, one technique for making judgments is MCDM. The process entails assessing multiple options according to pre-established standards in order to identify the optimal selection. In essence, when there are several variables to consider, MCDM assists in selecting the option. The Fuzzy Analytic Hierarchy Process (FAHP) is one of the various MCDMs which this paper uses to choose the best BCT platform for academic records based on three choices (IBM, Ethereum, and Hyperledger Fabric) and five factors (cost, degree of acceptance, simplicity of use, data security, and level of customization). The analysis's findings indicate that data security is the most crucial factor, with a weight of 0.645, and that IBM is the best BCT platform, with a value of 0.448. By comparing the FAHP results to those of AHP, IBM's suitability as a platform was confirmed.

A hyperbaric aerodynamic levitator has been developed for containerless materials research at specimen temperatures exceeding 2000 °C and pressures up to 10.3 MPa (1500 psi). This report describes the prototype instrument design and observations of the influence of specimen size, density, pressure, and flow rate on levitation behavior. The effect of pressure on heat transfer was also assessed by studying the heating and cooling behavior of levitated Al2O3 liquids. A threefold increase in the convective heat transfer coefficient was estimated as pressure increased to 10.3 MPa. The results demonstrate that hyperbaric aerodynamic levitation is a promising technique for containerless materials research at high gas pressures.

Abstract The isotopic composition of precipitation (δ18O, δ2H, and δ17O) is affected by evaporation and exchange as hydrometeors descend. These processes can significantly alter the isotopic ratio of precipitation relative to its initial condensation state in the cloud yet are exceedingly difficult to study in situ. The most widely utilized model for droplet‐atmosphere exchange was derived from controlled experiments where droplets were suspended by forced air in a narrow glass tube‐ a design that manipulated the structure of the boundary layer around the droplet. Here, we provide a novel experimental test of atmosphere‐hydrometeor isotopic exchange using the mechanism of acoustic levitation, where sound waves are projected vertically to levitate droplets in free‐flowing ambient air. We present results from a series of droplet levitation experiments where the droplets' surface temperatures were measured by a thermal camera and the background atmospheric isotope concentration was measured via cavity‐ringdown spectroscopy, providing a high degree of constraint on the fractionation conditions. We show that isotope enrichment of the suspended droplets met first order expectations based on existing models. However, to account for the slope of δ18O versus δ2H (i.e., the meteoric water line) and deuterium excess of the droplets as they evolved, we had to modify the existing model for droplet‐atmosphere exchange to account for the fact that some portion of the evaporative flux from the droplet remained present in the boundary layer around the droplet leading to an evolving feedback between droplet and the atmosphere‐that is, a quasi closed‐system effect. The isotopic enrichment of the boundary layer surrounding the droplet as a consequence of the closed‐system dynamics, drives more rapid δ18O isotope enrichment relative to δ2H of the droplet compared to what is predicted using an open system model. Although these were controlled experiments, they illustrate important dynamics regarding the isotopic signature of feedbacks between droplet evaporation and atmospheric humidity.

In this study, Ti-10Mo alloy powder and sintered bodies were successfully fabricated using a threestep process of acid/organic solvent cleaning, hydrogenation/dehydrogenation (HDH) of bulk Ti-Mo scrap, and pressureless vacuum sintering of the alloy powder. This process can be used to recycle valuable Ti alloy. And unlike remelting-based recycling processes, in which elements vaporize, this process maintains the original ratio of Ti and Mo and results in no loss of elements during HDH and sintering. We note, however, that the phases in the resulting Ti-Mo alloy were changed by HDH and the sintering processes, and as a result the phases of the alloy evolved differently than those of alloys prepared by the blending of Ti and Mo powders. XRD results of the processed sintered bodies revealed different pathways for the transformation of the crystal structure. As sintering temperature increased, the dominant phase changes in the crystal structure of the sintered bodies that used commercial powders were α' → α' + α'', while the phase changes for the recycled Ti-10Mo sintered bodies were α' + α'' → α'' + β. Although the density of the sintered body using commercial materials was generally higher at a lower sintering temperature than the density of the sintered body that used recycled powder, at 1673 K their respective densities were nearly identical. Moreover, the sintered body that contained scrap showed superior Vickers hardness after the dual phase (α + β) of Ti was reached, despite its relatively low density.

The atomic structural arrangements of liquid iron oxides affect the thermophysical and thermodynamic properties associated with the steelmaking process and magma flows. Here, the structures of stable and supercooled iron oxide melts have been investigated as a function of oxygen fugacity and temperature, using x-ray diffraction and aerodynamic levitation with laser heating. Total x-ray structure factors and their corresponding pair distribution functions were measured for temperatures ranging from 1973 K in the stable melt, to 1573 K in the deeply supercooled liquid region, over a wide range of oxygen partial pressures. Empirical potential structure refinement yields average Fe–O coordination numbers ranging from ~4.5 to ~5 over the region FeO to Fe2O3, significantly lower than most existing reports. Ferric iron is dominated by FeO4, FeO5 and FeO6 units in the oxygen rich melt. For ferrous iron under reducing conditions FeO4 and FeO5 units dominate, in stark contrast to crystalline FeO.

Incongruent liquid–liquid phase separation is a common phenomenon in molten oxides, but there are few structural studies as a result of the high temperatures involved, ca. >1600 °C. Here, we present a high-energy X-ray combined small-/wide-angle scattering (SAXS/WAXS) method that can directly probe non-equilibrium phase diagrams. The Porod exponent in the SAXS signal is extracted, which measures the roughness of the interface formed between different phases. Problematic volatilization of silica in Al2O3-, CaO-, and MgO-bearing silica-rich liquids was minimized using levitation, laser heating, and rapid time-resolved measurements (lasting tens of seconds), to probe the kinetics of the phase separation process. The WAXS measurement simultaneously probes the local atomic structure of the liquid state and shows that the primary structural changes are associated with the SiO2 network. Cation coordination numbers extracted from pair distribution functions support the model that the origin of phase separation in binary silicate systems is due to coulombic repulsions between poorly screened cations. For CaO–SiO2, the liquid–liquid phase separation is found to correlate with a pause in the temperature-dependent atomic disorder associated with SiO4 tetrahedra.