resumo
The tribological behaviour of homologous contacts between nanocrystalline diamond (NCD) chemically vapour deposited (CVD) coated parts is reviewed. The major part of the published works is related to silicon nitride ceramic coated materials. The NCD-on-NCD tribo-tests were performed under unlubricated and lubricated sliding conditions in water and in simulated physiological fluids (Hank's balanced salt solution, HBSS, and dilute fetal bovine serum, FBS). The friction and wear behaviour was assessed using a reciprocating motion setup under moderated to high applied normal loads (10-90 N), and up to 6 km of sliding distance. The inherent very low surface roughness of the NCD films was responsible for a very low steady-state friction response (0.01-0.05) in unlubricated and water-lubricated tests. Moreover, the running-in period of accommodation observed for conventional microcrystalline diamond coatings is greatly suppressed by the much lower starting surface roughness found in the NCD coatings. In distilled water, the NCD coatings displayed a remarkable tribological performance characterised by a high resistance to wear damage (10(-9) mm(3) N(-1) m(-1)), characteristic of very mild wear regimes, and high tribomechanical threshold loads (85 N) before film failure. Biotribological experiments conducted in HBSS resulted in similar friction and wear coefficients, while tribotesting in FBS revealed higher friction values (0.10) due to a protein attaching effect. (C) 2009 Elsevier B.V. All rights reserved.
palavras-chave
NANOCRYSTALLINE DIAMOND COATINGS; CVD DIAMOND; TRIBOLOGICAL PROPERTIES; FRICTION; FILMS; BEHAVIOR; PERFORMANCE; BIOTRIBOLOGY; PLASMAS; CARBON
categoria
Materials Science; Physics
autores
Amaral, M; Abreu, CS; Fernandes, AJS; Oliveira, FJ; Gomes, JR; Silva, RF
nossos autores
Filipe José Alves de Oliveira
Investigador Principal