The fluoride use for anodizing electrolytes has been primarily responsible for the formation of nanoporous oxides at valve metals, except aluminum, since it causes a dissolution process. This study presents the formation of an oxide model according to the following anodizing parameters: 100 V, 12.73 mA/cm², room temperature and the niobium samples anodized in niobium oxalate and oxalic acid electrolytes without and with the addition of HF for 5, 30 and 60 min. The anodized samples were analyzed morphologically by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM) and the hydrophobicity of the samples was assessed by the sessile drop method. The presence of fluor in the niobium oxalate electrolyte formed oxides with lower a dissolution and a low hydrophobicity compared to the one formed in oxalic acid was attributed to the incorporation of niobium and oxalate ions. Thereby, the model proposed in this paper showed that during anodization the migration of the fluoride ion into the oxide occurs at high speed, which results in the formation of microcones, leading to the formation of discrete layers of porous oxide.
Squeeze casting is the most industrially advantageous process for producing zamak 5 parts. However, this process generates porosity defects in parts, compromising their corrosion resistance. Therefore, this work aims to minimize defects and improve zamak 5 corrosive performance through the anodizing process. For this purpose, zamak 5 was anodized in 300 mol.m -3 oxalic acid and analyzed by ATR-FTIR, SEM, wettability and EIS techniques. The anodizing process promoted the formation of oxalate and oxide layers of Zn and Al, thereby reducing porosity defects. Although the anodized layer has fragile behavior, being porous and permeable, the immersion time of anodized zamak 5 in NaCl forms corrosion products in the alloy that exhibit better protection.
Este é um artigo publicado em acesso aberto (Open Access) sob a licença Creative Commons Attribution, que permite uso, distribuição e reprodução em qualquer meio, sem restrições desde que o trabalho original seja corretamente citado. a ResumoOs fatores críticos que determinam a aplicação do titânio e suas ligas para implantes biomédicos são suas propriedades mecânicas e químicas, seguidas pela excelente resistência à corrosão e biocompatibilidade. Com isso, a anodização tem sido usada para favorecer a formação de superfícies porosas que melhoram o processo de osseointegração do titânio, buscando propriedades que possam estimular o crescimento do osso neoformado. No entanto, esse processo utiliza eletrólitos à base de ácido fluorídrico (HF), o qual é nocivo para a saúde do operador. O objetivo deste estudo é obter superfície porosa de titânio em eletrólitos livres de F -. Desta forma, amostras de titânio foram anodizadas em eletrólitos de ácido sulfúrico com e sem adição peróxido de hidrogênio, em diferentes concentrações (1/2, 1 e 2 M H 2 O 2 ) a fim de obter superfície porosa de óxido de titânio. O crescimento dos óxidos foi avaliado por meio de transientes de anodização e as amostras obtidas foram analisadas ao MEV. As amostras apresentaram a formação de óxidos contendo poros, de dimensões nanométricas. Portanto, este estudo mostra uma alternativa a formação de porosidade, sem uso de eletrólito a base de HF, com potencial aplicação em biomateriais. Palavras-chave: Titânio; H 2 SO 4 ; H 2 O 2 ; Anodização; Biomaterial.
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