1. Metal-Supported Niobium Catalysts Investigation for Conversion of Bio-Renewable Glycerol to Organic Compounds

The glycerol oxidative dehydration to organic compounds, especially acrolein and acrylic acid, was studied over vanadium, molybdenum, and cobalt oxides supported on niobium oxide and niobium phosphate catalysts. At 300 °C, the glycerol conversion was 100% over all catalysts tested, and acrolein was the main product observed, without significant deactivation

Journal of the Brazilian Chemical Society. Publicado em: 2022

2. Influence of the addition of niobium oxide on the properties of fused aluminum oxide used in abrasive tools

Abstract Fused alumina is a material used in the manufacturing of abrasive tools, due to its high fusion point, great hardness, and mechanical toughness. In this context, this study addressed the influence of niobium addition on the properties of fused alumina for abrasive applications. A comparison was also made between this oxide and the brown fused alumin

Cerâmica. Publicado em: 2022

3. Synthesis and characterization of niobium-doped fish scale-derived hydroxyapatite by physical ultrasound interference

Abstract Fish scales of the Arapaima gigas (pirarucu) species were heat-treated to obtain natural hydroxyapatite (HAp), and it was doped with niobium (Nb) by physical ultrasound interference to confirm an effective route to the production of Nb-doped HAp powders. The effect of ultrasound application on doping was investigated. The structure of the powders wa

Cerâmica. Publicado em: 2021-03

4. Magnetic and Mesoporous Silica-Niobia Material as Modifier of Carbon Paste Electrode for p-Nitrophenol Electrochemical Determination

In the present work, the sol-gel synthesis method was employed as strategy to obtain a magnetic and mesoporous silica-niobia material. The planned synthesis was based on the hetero-condensation of niobium and silicon alkoxide precursors, in the presence of spherical magnetite particles. The resulting material presented interesting characteristics such as mag

J. Braz. Chem. Soc.. Publicado em: 2021-03

5. The Surface Treatment of Niobium Superconducting Reentrant Cavities by Means of High Temperature Nitrogen Plasma Based Ion Implantation

High Temperature Nitrogen Plasma Based Ion Implantation (HT-NPBII) has been used to treat the surface of niobium superconducting reentrant cavities, which are part of parametric transducers in a resonant-mass gravitational wave detector. The aim is to enhance the corresponding electrical quality factors (Q-factors) which are closely related with the increase

Mat. Res.. Publicado em: 13/12/2019

6. Microstructural Evolution and Phase Transformation of a Ti-5Nb-5Al Alloy During Annealing Treatment

The microstructural evolution and phase transformation of a Ti-5Nb-5Al alloy during isothermal annealing treatment were studied in this paper. The microstructural evolution was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with X-ray energy dispersive spectroscopy (EDS) and electron backscattering diffraction (EBSD). The fi

Mat. Res.. Publicado em: 05/12/2019

7. Characterization of Austenite Decomposition in Steels with Different Chemical Concepts and High Potential to Manufacture Seamed Pipes for Oil and Gas Industry

This work presents the characterization of austenite decomposition kinetics in two steels during continuous cooling considering non-deformed austenite grains. Two different chemical concepts of steels were evaluated: low carbon - high manganese and a relatively new concept based on low carbon - low manganese - high niobium contents. Dilatometric experiments,

Mat. Res.. Publicado em: 21/10/2019

8. Simple Niobium Catalysts Applied in Reflux and Ultrasound-Assisted Systems for Biofuel Synthesis

Using niobium compounds as heterogeneous catalysts in biodiesel production is a promising methodology from economic and environmental viewpoints. However, the application of niobium catalysts still is a challenge due to the high temperatures and pressures for moderate biofuel yields. Therefore, easily handled and applied materials have been developed to opti

J. Braz. Chem. Soc.. Publicado em: 16/09/2019

9. Characterization of Ti-35Nb alloy surface modified by controlled chemical oxidation for surgical implant applications

ABSTRACT Titanium-Niobium alloys have been studied for biomedical applications due to their satisfactory biocompatibility. In order to improve the long-term implantation, surface modification techniques have been developed to generate suitable topography, roughness, chemical composition, surface energy, etc. Considering this approach, the present work aimed

Matéria (Rio J.). Publicado em: 16/09/2019

10. Study of the Nb2O5 Insertion in ZnO to Dye-sensitized Solar Cells

Dye-sensitized solar cells (DSSC) have received much attention as an alternative to silicon-based solar cells, due to various advantages. Zinc oxide (ZnO) is an n-type semiconductor employed as photoanode on DSSC. The decrease of charge recombination is an efficient strategy capable of improving the photovoltaic performance of the device. In this perspective

Mat. Res.. Publicado em: 01/07/2019

11. Analysis of the densification of a composite obtained by sintering process of aluminum bronze powders with different carbides

Abstract Aluminum bronze alloy is applied in environments that require materials of high mechanical resistance and wear, such as marine, oil & gas and aerospace ones. This study analyzes the densification of composites based on aluminum bronze with additions of the vanadium (VC) and niobium (NbC) carbides, and the influence of these carbides in the milling e

REM, Int. Eng. J.. Publicado em: 19/06/2019

12. Influência da microestrutura na resistência ao desgaste microabrasivo de ligas de F-Cr-C e Fe-Cr-C-Nb

ABSTRACT Neste trabalho é feita uma avaliação da influência do teor de cromo e da combinação do cromo e nióbio em ligas de revestimento duro do tipo Fe-Cr-C, na microestrutura e propriedades que envolvam a resistência ao desgaste microabrasivo. Vários estudos têm sido realizados em busca de informações conclusivas sobre este sistema em condiçõe

Matéria (Rio J.). Publicado em: 20/05/2019