Tecnologia em Metalurgia, Materiais e Mineração
https://tecnologiammm.com.br/article/doi/10.4322/2176-1523.1310
Tecnologia em Metalurgia, Materiais e Mineração
Artigo Original

OBTAINING NIOBIUM OXIDES IN ACETIC ACID WITH ADDITION OF HF

OBTENÇÃO DE ÓXIDOS DE NIÓBIO EM ÁCIDO ACÉTICO COM ADIÇÃO DE HF

Marcolin, Patrícia; Longhi, Marielen; Caio, Letícia; Zini, Lucas Pandolphi; Beltrami, Lilian Vanessa Rossa; Silva, Jéssica Cristina; Morisso, Fernando Dal Pont; Kunst, Sandra Raquel; Oliveira, Claúdia Trindade

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Abstract

During anodizing, the chemical attack of hydrofluoric acid (HF) electrolytes on niobium can promote the formation of oxides with porous structures. However, this chemical attack can also cause an intense dissolution of the oxide during its formation. This effect can be minimized by varying the HF concentration of the anodizing electrolyte, thereby controlling the growth of the porous oxide. Studies have alternative electrolytes that do not use HF to obtain porous oxides. Thus, organic electrolytes, such as acetic acid, may be a viable alternative. In this context, the objective of this study is to obtain and evaluate the anodization of niobium in acetic acid at different current densities (10, 20 and 50 mA/cm2 ) and to study the influence of the addition of HF to the electrolyte. The results showed that the anodized anodic in acetic acid, under conditions of 100 V and 10 mA/cm2 , presented porous oxide with less defects. Therefore, this result indicates that it is possible to produce porous niobium oxides by anodizing in HF-free electrolyte.

Keywords

Niobium, Anodizing, Acetic acid.

Resumo

Durante a anodização, o ataque químico de eletrólitos de ácido fluorídrico (HF) sobre o nióbio pode promover a formação de óxidos com estruturas porosas. Contudo, este ataque químico pode causar uma intensa dissolução do óxido durante sua formação. Esse efeito pode ser minimizado variando-se a concentração de HF do eletrólito de anodização, controlando assim o crescimento do óxido poroso. Estudos têm buscado por eletrólitos alternativos que não utilizam HF na obtenção de óxidos porosos. Logo, eletrólitos orgânicos, como o ácido acético, podem ser uma alternativa viável. Neste contexto, o objetivo deste estudo é obter e avaliar a anodização de nióbio em ácido acético em diferentes densidades de correntes (10, 20 e 50 mA/cm2 ) e estudar a influencia da adição de HF ao eletrólito. Os resultados mostraram que a amostra de nióbio anodizada em ácido acético, nas condições de 100 V e 10 mA/cm2 , apresentou óxido proroso com menor quantidade de defeitos. Portanto, este resultado indica que é possível a formação de óxidos de nióbio porosos por anodização em eletrólito livre de HF.

Palavras-chave

Nióbio, Anodização, Ácido acético.

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