tribologia

C.S. Abreu et al.

Revestimentos de Diamante CVD em Si3N4

Revestimentos de Diamante CVD em Si3N4: Atrito e Desgaste no
Deslizamento de Pares Próprios sem Lubrificação
C.S. Abreu(1)*, F.J. Oliveira(2), M. Belmonte(3), A.J.S. Fernandes(4), R.F. Silva(2), J.R. Gomes(5)
(1)*

Departamento de Física, Instituto Superior de Engenharia do Porto, ISEP, Portugal [e-mail] (2)

Departamento de Engenharia Cerâmica e do Vidro, CICECO, Universidade de Aveiro, Portugal
(3)
Instituto de Cerámica y Vidrio, CSIC, Cantoblanco, Madrid, Espanha
(4)
Departamento de Física, Universidade de Aveiro, Portugal
(5)
Departamento de Engenharia Mecânica, CIICS, Universidade do Minho, Portugal

ABSTRACT: Due to its extreme hardness natural diamond posses a high wear resistance. However, apart from the high cost, it is characterised by a strong anisotropy in terms of tribological behaviour. These limitations are overcome using diamond coatings produced by chemical vapour deposition (CVD) which due to their polycristalline nature, while retaining the extreme properties of natural diamond, make surfaces with high tribological performance.
CVD diamond coatings can be deposited on various types of substrates. However, in order to sustain high levels of adhesion, silicon nitride (Si3N4) based ceramics constitute a particularly attractive substrate material due to its carburizing nature and low thermal expansion coefficient mismatch with diamond.
In the present work, dense Si3N4 samples were diamond coated using the microwave plasma activated chemical vapour deposition (MPCVD) technique. The tribological tests were performed using a ball-on-flat (BOF) configuration on self-mated diamond CVD pairs, without the presence of lubrication in ambient atmosphere. The applied normal varied in the range 1080 N, while keeping the frequency (1 Hz) constant throughout the tests.
The tribological behaviour was characterised by extremely low steady-state friction coefficient