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vol.47 número303Tratamentos para obtenção de TaC em superfície de grafite. Parte I: Imersão em solução aquosa de TaF7(2-)Tratamentos para obtenção de TaC em superfície de grafite. Parte III: Imersão em suspensão Aquosa de Ta e Ta2O5 índice de autoresíndice de assuntospesquisa de artigos
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Cerâmica

versão impressa ISSN 0366-6913versão On-line ISSN 1678-4553

Resumo

IZARIO Fº, H. J. et al. TaC formation on graphite surface. Part II: electrodeposition from molten fluorides. Cerâmica [online]. 2001, vol.47, n.303, pp.149-152. ISSN 0366-6913.  http://dx.doi.org/10.1590/S0366-69132001000300004.

This paper presents tantalum electrodeposition in molten fluorides followed by thermal treatment, as a pre-treatment technique to graphite tubes used in spectrometry of atomic absorption in graphite oven. The experiments were carried out using the eutectic FLINAK with addition of 15% (weight %) of K2TaF7. The tantalum anodes were made of tantalum commercial scrap; the cathode was the graphite tube to be electroplated. Tantalum coatings were obtained with high current efficiency at 750 o C temperature, 20 mA.cm-2 current density and 120 minutes electrolysis time, under controlled argon atmosphere. The thermal treatment under argon atmosphere was effective to obtain a perfect tantalum carbide layer; X-ray diffraction analysis confirmed tantalum carbide formation. Based on the scanning electronic microscopy analysis results, it was found that the tantalum carbide deposits were adherent to the substrate and were free of porosities, incrustations and microcracks.

Palavras-chave : electrodeposition; graphite; molten fluorides; tantalum carbide.

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