First Results of Cavitation Erosion Behavior of Plasma Nitrided Niobium: Surface Modification

• Autor(a) principal: Kertscher,Ricardo
• Data de Publicação: 2015
• Outros Autores: Moraes,Juliana Martins de, Henke,Sérgio, Allenstein,Angela Nardelli, Silva,Regis Henrique Gonçalves e, Dutra,Jair Carlos, Brunatto,Silvio Francisco
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Materials research (São Carlos. Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000601242
• topic: cavitation-erosion; niobium nitride; plasma nitriding; niobium

This work presents the first results of the plasma nitriding study performed in pure niobium in order to increase its cavitation erosion resistance. Samples were prepared from 98.9% purity and 90% reduction cold-rolled niobium bars. Annealing treatment of the cold-worked niobium samples was carried out in vacuum furnace at 1.33 Pa pressure, in the temperature of 1000 °C, for a time of 60 min. Annealed samples showing hardness of 80 HV were cut to dimensions of 20 × 30 × 4 mm3. Nitriding treatment was conducted at 1080 °C, gas mixture of 90% N2 + 10% H2, flow rate of 5 × 10–6 Nm3s–1, and pressure of 1200 Pa (9 Torr), for a total time of 4 h comprised by two treatment steps of 2 h each. For comparison purpose, results for nitrided and non-nitrided niobium are confronted. Samples were characterized by XRD, nanoindentation, microhardness, SEM, and 2D surface topography and 3D interferometry profile analysis techniques. Cavitation testing was conducted according to ASTM G32-09. Comparatively, promising results based on the formation of niobium nitride phases in treated surfaces are presented and discussed in the present work.