Instituto Superior Técnico

About: Instituto Superior Técnico is a based out in . It is known for research contribution in the topics: Catalysis & Finite element method. The organization has 10085 authors who have published 30226 publications receiving 667524 citations. The organization is also known as: IST & Instituto Superior Tecnico.

More sustainable approaches for the synthesis of N-based heterocycles.

Abstract: Centro de Quı́mica-Fı́sica Molecular (CQFM) and Institute of Nanosciences and Nanotechnology (IN), Departamento de Engenharia Quı́mica e Biológica, Instituto Superior Técnico, 1049-001 Lisboa, Portugal, REQUIMTE, Departamento de Quı́mica, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal, and iMed.UL, Faculdade de Farmácia da Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal

Mechanism of corrosion inhibition of AA2024 by rare-earth compounds.

Abstract: The mechanism of corrosion protection of the widely used 2024-T3 aluminum alloy by cerium and lanthanum inhibitors in chloride media is described in detail in the present work. The corrosion process was investigated by means of scanning Kelvin probe force microscopy (SKPFM), in situ atomic force microscopy, and scanning electron microscopy coupled with energy dispersive spectroscopy. Employment of the high-resolution and in situ techniques results in a deep understanding of the details of the physical chemistry and mechanisms of the corrosion processes. The applicability of the SKPFM for mechanistic analysis of the effect of different corrosion inhibitors is demonstrated for the first time. The inhibitors under study show sufficient hindering of the localized corrosion processes especially in the case of pitting formation located around the intermetallic S-phase particles. The main role of Ce(3+) and La(3+) in the corrosion protection is formation of hydroxide deposits on S-phase inclusions buffering the local increase of pH, which is responsible for the acceleration of the intermetallics dealloying. The formed hydroxide precipitates can also act as a diffusion barrier hindering the corrosion processes in active zones. Cerium nitrate exhibits higher inhibition efficiency in comparison with lanthanum nitrate. The higher effect in the case of cerium is obtained due to lower solubility of the respective hydroxide. A detailed mechanism of the corrosion process and its inhibition is proposed based on thermodynamic analysis.

Mechanical behaviour of non-structural concrete made with recycled ceramic aggregates

Abstract: In order to reduce the volume of ceramic waste from the construction industry, it is possible, among other applications, to use it as aggregates in the production of non-structural concrete artefacts. The main characteristics of such aggregates as well as those of the fresh and hardened concrete made with them (after a standardized pre-saturation procedure) are presented here and compared with those of conventional materials (primary stone aggregates and the concretes made exclusively with them), within a larger experimental investigation to maximize the reuse and reutilization of construction and demolition waste. The results show that there is a potential for the use of these ceramic aggregates in elements in which the primary requirement is not compressive strength but tensile strength and abrasion resistance, such as for concrete pavement slabs.