Niobium and niobium-iron coatings on API 5LX 70 steel applied with HVOF

• Autor(a) principal: Brandolt, Cristiane de Souza
• Data de Publicação: 2014
• Outros Autores: Souza Júnior, Jair Garcia de, Kunst, Sandra Raquel, Ortega Vega, Maria Rita, Schroeder, Roberto Moreira, Malfatti, Célia de Fraga
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/115523
• topic: Nióbio; Resistência à corrosão; Aspersão térmica; Aço; Revestimento; Coatings; Niobium; HVOF; API 5L X70 steel

The present study aimed to create and characterize niobium and niobium-iron60% coatings applied to steel API 5L X70 using the hypersonic thermal spray process (HVOF). The morphologies of the coatings were analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and profilometry, while the coatings’ hardnesses was evaluated using the Vickers hardness test. The coatings’ corrosion resistance was evaluated by monitoring their open circuit potential and potentiodynamic polarization and performing electrochemical impedance spectroscopy in a 0.05 M NaCl solution. The results showed that the niobium-iron coating contained minor porosity regions, while such defects occurred over large regions of the niobium coating. In terms of corrosion resistance, the coatings obtained in this work promoted a reduction in the substrate’s corrosion rate, but the presence of discontinuities such as porosity compromised the barrier effects of these coatings.