Enhanced performance of HFCVD nanocrystalline diamond self-mated tribosystems by plasma pretreatments on silicon nitride substrates |
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Authors: | C.S. Abreu M. Amaral F.J. Oliveira A.J.S. Fernandes J.R. Gomes R.F. Silva |
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Affiliation: | aPhysics Department, Porto Superior Engineering Institute, ISEP, 4200-072 Porto, Portugal;bCeramics and Glass Eng. Department, CICECO, University of Aveiro, 3810-193 Aveiro, Portugal;cPhysics Department, University of Aveiro, 3810-193 Aveiro, Portugal;dMechanical Eng. Department, CIICS, University of Minho, 4800-058 Guimarães, Portugal |
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Abstract: | Nanocrystalline diamond (NCD) coatings were grown by the hot-filament chemical vapour deposition (HFCVD) method on hydrogen plasma pretreated silicon nitride (Si3N4) substrates. The friction and wear behaviour of self-mated NCD films, submitted to unlubricated sliding and high applied loads (up to 90 N), was assessed using an oscillating ball-on-flat configuration in ambient atmosphere. The reciprocating tests revealed an initially high friction coefficient peak, associated to the starting surface roughness of NCD coatings (Rq = 50 nm). Subsequently, a steady-state regime with low friction coefficient values (0.01–0.04) sets in, related to a smoother (Rq = 17 nm) tribologically modified surface. A polishing wear mechanism governing the material loss was responsible for mild wear coefficients (k 10− 7 mm3 N− 1 m− 1). The hydrogen etching procedure notably increased the film adhesion with respect to untreated surfaces as demonstrated by the high threshold loads (60 N; 3.5 GPa) prior to film delamination. |
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Keywords: | Nanocrystalline Diamond film Hot filament CVD Tribology |
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