Missouri University of Science and Technology

About: Missouri University of Science and Technology is a education organization based out in Rolla, Missouri, United States. It is known for research contribution in the topics: Artificial neural network & Control theory. The organization has 9380 authors who have published 21161 publications receiving 462544 citations. The organization is also known as: Missouri S&T & University of Missouri–Rolla.

How much particle surface corrugation is sufficient to improve aerosol performance of powders

Abstract: Purpose. The current study aimed to quantify the different degree of particle surface corrugation and correlate it to the aerosol performance of powders.

Nickel telluride as a bifunctional electrocatalyst for efficient water splitting in alkaline medium

Abstract: Designing efficient electrocatalysts has been one of the primary goals for water electrolysis, which is one of the most promising routes towards sustainable energy generation from renewable sources. In this article, we have tried to expand the family of transition metal chalcogenide based highly efficient OER electrocatalysts by investigating nickel telluride, Ni3Te2 as a catalyst for the first time. Interestingly Ni3Te2 electrodeposited on a GC electrode showed very low onset potential and overpotential at 10 mA cm−2 (180 mV), which is the lowest in the series of chalcogenides with similar stoichiometry, Ni3E2 (E = S, Se, Te) as well as Ni-oxides. This observation falls in line with the hypothesis that increasing the covalency around the transition metal center enhances catalytic activity. Such a hypothesis has been previously validated in oxide-based electrocatalysts by creating anion vacancies. However, this is the first instance where this hypothesis has been convincingly validated in the chalcogenide series. The operational stability of the Ni3Te2 electrocatalyst surface during the OER for an extended period of time in alkaline medium was confirmed through surface-sensitive analytical techniques such as XPS, as well as electrochemical methods which showed that the telluride surface did not undergo any corrosion, degradation, or compositional change. More importantly we have compared the catalyst activation step (Ni2+ → Ni3+ oxidation) in the chalcogenide series, through electrochemical cyclic voltammetry studies, and have shown that catalyst activation occurs at lower applied potential as the electronegativity of the anion decreases. From DFT calculations we have also shown that the hydroxyl attachment energy is more favorable on the Ni3Te2 surface compared to the Ni-oxide, confirming the enhanced catalytic activity of the telluride. Ni3Te2 also exhibited efficient HER catalytic activity in alkaline medium making it a very effective bifunctional catalyst for full water splitting with a cell voltage of 1.66 V at 10 mA cm−2. It should be noted here that this is the first report of OER and HER activity in the family of Ni-tellurides.

Optimization and performance of cost-effective ultra-high performance concrete

Abstract: This paper presents a mix design method for ultra-high performance concrete (UHPC) prepared with high-volume supplementary cementitious materials and conventional concrete sand. The method involves the optimization of binder combinations to enhance packing density, compressive strength, and rheological properties. The water-to-cementitious materials ratio is then determined for pastes prepared with the selected binders. The sand gradation is optimized using the modified Andreasen and Andersen packing model to achieve maximum packing density. The binder-to-sand volume ratio is then determined based on the void content, required lubrication paste volume, and compressive strength. The optimum fiber volume is selected based on flowability and flexural performance. The high-range water reducer dosage and w/cm are then adjusted according to the targeted mini-slump flow and compressive strength. Finally, the optimized UHPC mix designs are evaluated to determine key properties that are relevant to the intended application. This mix design approach was applied to develop cost-effective UHPC materials. The results indicate that the optimized UHPC can develop 28-days compressive strength of 125 MPa under standard curing condition and 168–178 MPa by heat curing for 1 days Such mixtures have unit cost per compressive strength at 28 days of 4.1–4.5 $/m3/MPa under standard curing.

Effect of tool geometry on static strength of friction stir spot-welded aluminum alloy

Abstract: Friction stir spot welding is performed on 5083 Al alloy using tools with a conventional cylindrical pin and the proposed triangular pin. Partial metallurgical bond (called as ‘hook’) is formed in the weld region between the overlapped metal sheets. The tool-pin geometry significantly affects the hook shape. Under the same process condition, welds made with the cylindrical pin have a continuous hook which bypasses the stir zone and points downward towards the weld bottom. By contrast, for welds made with the triangular pin, the hook is directed upwards and then arrested at the periphery of the stir zone. The difference in the hook shape could be attributed to the asymmetric rotation of the triangular pin that may cause the material in the vicinity of the pin to move back and forth in the radial direction resulting in the hook being broken-up (dispersed) in the stir zone. In addition, the triangular pin results in a finer grain structure in the stir zone compared to the cylindrical pin. Static strength of welds made with the triangular pin is twice that of welds made with the cylindrical pin, which is attributed to the finer grain size as well as tensile failure mode as a result of the arrested hook.