Precipitation Chromium
Mostrando 1-12 de 33 artigos, teses e dissertações.
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1. STUDY OF THE CHROMIUM(VI) REMOVAL FROM AQUEOUS SYSTEMS BY COBALT NANOPARTICLES
The cobalt nanoparticles (NPs-Co) were synthesized and applied in the removal of Cr(VI). The obtained nanomaterials presented magnetic properties and were characterized by the techniques of Transmission Electron Microscopy and X-ray diffraction. The NPs-Co, with a diameter of less than 50 nm, had a composition based on metallic cobalt and cobalt oxide. The N
Quím. Nova. Publicado em: 18/07/2019
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2. Characterization of the Austenite Reformation Mechanisms as a Function of the Initial Ferritic State in a UNS S32304 Duplex Stainless Steel
Aiming to better understand the effects of heat treatment parameters on Ferrite-Austenite phase transformation in a 2304 duplex stainless steel different thermal cycles were applied to this steel in a quenching dilatometer. The obtained microstructures were characterized by optical microscopy, transmission electron microscopy and electron backscatter diffrac
Mat. Res.. Publicado em: 17/08/2017
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3. Martensitic Stainless Steels Low-temperature Nitriding: Dependence of Substrate Composition
Low-temperature plasma assisted nitriding is a very promising technique to improve surface mechanical properties of stainless steels, keeping unaltered or even improving their surface corrosion resistance. During treatment, nitrogen diffuses into the steel surface, increasing its hardness and wear resistance. In the present work the nitriding process of diff
Mat. Res.. Publicado em: 2015-06
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4. Nitrogen Surface Enrichment of Austenitic Stainless Steel ISO 5832-1: SHTPN vs Low-temperature Plasma Nitriding
Specimens of ISO 5832-1stainless steel were submitted to low temperature plasma nitriding treatment and Solution Heat Treatment after Plasma Nitriding (SHTPN) process aiming to obtain a S-phase, chromium precipitates-free, surface layer. The following techniques were used for analysis: scanning electron microscopy (SEM), optical microscopy (OM), microhardnes
Mat. Res.. Publicado em: 2015-06
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5. Naphthenic corrosion resistance, mechanical properties and microstructure evolution of experimental Cr-Mo steels with high Mo content
One method to face the effects of naphthenic acid corrosion in petroleun refining plants is to use alloys with good resistance to this kind of corrosion. For this purpose, molybdenum additions to chromium containing steels are specially recommended. In this work, experimental Fe-9Cr-xMo (x = 5, 7 and 9 wt. (%)) ingots were cast, forged and hot rolled before
Materials Research. Publicado em: 29/02/2012
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6. Cathodic cage nitriding of AISI 409 ferritic stainless steel with the addition of CH4
AISI 409 ferritic stainless steel samples were nitrided using the cathodic cage plasma nitriding technique (CCPN), with the addition of methane to reduce chromium precipitation, increase hardness and wear resistance and reduce the presence of nitrides when compared to plasma carbonitriding. Microhardness profiles and X-Ray analysis confirm the formation of a
Materials Research. Publicado em: 24/02/2012
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7. Caracterização da resistência à corrosão de ligas de alumínio após tratamentos alternativos à cromatização, com e sem revestimento orgânico / Characterization of the corrosion resistance of aluminum alloys after alternative treatmentes the chromate, with and without organic coating
In this study, the protective properties provided by new surface treatments for aluminum aiming the replacement of treatments that are harmful to the environment and human health, have been evaluated. The following treatments were investigated: passivation in solution with trivalent chromium ions, surface modification with self assembling molecules (SAM), im
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 14/03/2011
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8. Evaluatin of metabisulfite and a commercial stee wool for removing chromium (VI) from wastewater.
Efficiency of metabisulfite and a commercial steel wool as reducing agents in the removal of Cr(VI) from wastewaters was evaluated. Chromium( VI) was converted to Cr(III), precipitated with NaOH, and removed by filtration. A reduction of more than 1.0 x 10(5) and 4.0 x 10(5) fold in total Cr and the Cr(VI) concentrations, respectively, was observed by employ
Enviromental Chemistry Letter. Publicado em: 2011
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9. RemoÃÃo de Sulfato em Efluentes de Curtume usando Processo BiolÃgico / Sulfate removal in tannery wastewater using biological processes
A dissertaÃÃo teve como objetivo analisar a estabilidade e eficiÃncia do processo anaerÃbio de reduÃÃo de sulfato aplicado ao tratamento de efluente de um curtume. Utilizaram-se dois reatores anaerÃbios de manta de lodo e fluxo ascendente (UASB-Upflow Anaerobic Sludge Blanket), com capacidade de 3,0 litros, temperatura constante de 29+2ÂC e tempo de
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 11/08/2010
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10. InfluÃncia do Teor de Cromo e MolibdÃnio na Microestrutura e na Textura de Ligas Fe-Cr-Mo / INFLUENCE OF CONTENT OF CHROMIUM AND MOLYBDENUM MICROSTRUCTURE AND TEXTURE IN ALLOY Fe-Cr-Mo
The effects of chemical composition on texture and microstructure of five Fe-Cr-Mo alloys with 17%, 15% and 9% chromium contents and 5%, 7% and 9% molybdenum contents were investigated. The thermodynamic study of alloys for all investigated compositions showed the presence of secondary phases such as Mu (μ), Chi (χ), Sigma (σ) and a ferritic m
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 08/07/2010
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11. Programa de gerenciamento de resíduos químicos do CENA/USP: avaliação, ações de aperfeiçoamento e de extensão / Chemical waste management program of CENA/USP: assessment, improvement and extension actions
The generation of chemical waste in industry is very high, therefore the effluent discharge has been monitored by environmental inspections with greater intensity, to avoid environment contamination. The volume of waste generation is very small in universities, but the diversity is too large, what makes the treatment more difficult. Nevertheless, there are a
Publicado em: 2010
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12. Cinética de envelhecimento de aços dual phase de baixa resistência mecânica laminados a frio
The kinetics of static strain aging in cold rolled Dual Phase steels of the 250/450 MPa grade of mechanical strength was studied by means of tensile tests. Two Dual Phase steels, with and without a chromium addition of 0.36wt%, were studied in a pilot scale. After the continuous annealing step, carried out in a Gleeble machine model 3500, the specimens were
Publicado em: 2009