The electrocatalytic properties of steel-FeNbC composites were evaluated after potentiostatic ageing with the purpose of establishing the potential use of such materials as electrodes for the industrial production of oxygen. The effect of processing parameters, involved in the production of the composites by powder metallurgy, such as milling conditions and compaction pressure, on the performance of the electrodes was also studied. The electrodes were characterized according to their electrical resistance in NaOH 1M solution, considering that the purpose of the application requires this value to be ~ 0.5 .cm 2 . This parameter was evaluated from repetitive electrochemical measurements carried out from 0.7 V to 1.5 V (vs. Ag/AgCl) by electrode anodization. Changes in the electrochemical behavior of the electrodes, especially concerning the O 2 evolution in alkaline medium, were studied as a function of the applied potential. The results revealed that the electrocatalytic activity of the electrodes increased upon ageing, probably as a consequence of the growth of oxide layers and/or increase in the conductivity of the material, resulting in current gain and corresponding decrease in the polarization resistance to 0.75 cm 2 .

Several kinds of alloys Ni-based, Fe-based and Al-based oxide dispersion strengthened (ODS) and carbide dispersion strengthened (CDS) have been produced through mechanical alloying. Precipitation-strengthened or dispersion-strengthened steels are a kind of high strengthened steel using fine precipitation or dispersion of carbides. This work present a study of EUROFER97 steel powder reinforced with 3%wt of niobium carbide. The starting materials were wet-milled in a high-energy planetary ball mill for several times up to 5 hours. The ratio of ball to powder weight was 15:1. The milled powders were characterized by SEM, XRD, EDX and laser scattering. The results are presented on base of a microstructure analysis of composite particles of steel-carbide as a function of milling time.

Particle reinforced metal matrix composites have received considerable interest over many years and continue still under constant development to gain wider industrial applications. New technique of production of carbetos of refractory metals (WC, NbC, TaC, TaxNby) has been developed, synthesizing nanostructured carbides that show improvement of diverse properties of the materials to the gotten ones for the conventional processes. The properties of sintered composites are determined not only by the nature and quality of the raw materials employed but also by microstructure and porosity resulting from the processing techniques e sintering method. In this study, additions of 20 wt% NbC nanoparticles or micro-particles in the ferrite matrix were performed with the aim of improving the mechanical and use properties. Ancorsteel Fe 1000B powder from Hoengans Corp. was used together with the graphite, and a small amount of Fe3P, to induce liquid phase sintering. NbC nanoparticles or micro-particles were inserted into the Fe 1000B matrix by wet grinding (acetone) in a mill of planetary type of high energy. The angular velocity of the mill was kept constant at 300 rpm with milling time of 10 hours. The composites powders milled were annealed at 900 ° C for 1 hour under flowing hydrogen e argon, and a priori were pressed into cylindrical pellets under 600 MPa and sintered the plasma. Finally, the sintered pellets were evaluated through the testing: SEM, microhardness and density. It was noticeable the behavior of the composites Fe 1000B - NbC was affected by the content of nanoparticles of NbC added as well as by processing parameters, particularly plasma sintering.

This paper presents the results of tests for characterization of soil samples collected in Mossoró-RN, UFERSA-RN Campus (5 ° 12'34 .68 "South latitude, 37 ° 19 '5.74 "west longitude), for the purpose of producing soil-cement for the manufacture of pressed blocks. Objective of improving the quality of soil-cement, and provide conditions for the use of the soil making it ideal for the production of soil-cement block. Tests of compaction, particle size analysis, plastic limit, liquid limit and correct particle size, X-ray fluorescence and morphology by scanning electron microscopy (SEM). It was concluded that the soil needs correction particle size, due to the high clay content. The method combined grading, sieving, sedimentation and blooming X-ray as the fastest and most accurate in correcting soil particle size.

No Rio Grande do Norte, a extração de rochas ornamentais é responsável pela grande geração de resíduos sólidos, dentre eles o pó de rocha ornamental (RPRO). Dessa maneira, visando contribuir com o desenvolvimento sustentável, o presente trabalho possui como objetivo realizar a caracterização de dois resíduos de RPRO do Seridó Potiguar. Para isso, realizou-se os ensaios de FRX, DRX, granulometria a laser e MEV. Através do estudo realizado, verificou-se viabilidade técnica de utilização desses resíduos na indústria de construção civil, com adição em argamassas. As amostras contêm predominância de sílica; em menores proporções óxido de potássio, óxido de ferro, óxido de fósforo, óxido de alumina e óxido de cálcio. Os resultados de DRX apresentam predominância de fases mineralógicas cristalinas. Na análise de MEV, as amostras apresentaram partículas de tamanhos variados, com morfologia irregular e angular. Possuem diâmetro médio de partícula de 23.84µm e 18.71µm. Os resíduos caracterizados possuem potencial de efeito filler para adições minerais em argamassas autonivelantes.