Damage progression in silicon nitride undergoing non-conforming hybrid cyclic contact

0481381 - ÚFM 2018 RIV GB eng J - Journal Article
Raga, R. - Khader, I. - Chlup, Zdeněk - Kailer, A.
Damage progression in silicon nitride undergoing non-conforming hybrid cyclic contact.
International Journal of Fatigue. Roč. 105, DEC (2017), s. 97-110. ISSN 0142-1123. E-ISSN 1879-3452
EU Projects: European Commission(XE) 263476 - ROLICER
Institutional support: RVO:68081723
Keywords : Silicon nitride * Cyclic contact fatigue * Surface and subsurface damage
OECD category: Audio engineering, reliability analysis
Impact factor: 3.132, year: 2017

Bearings experience one of the most severe mechanical loading of all machine elements. The contact
stresses engendered are highly localised and bound to a very small volume of the material. The aim of
this study was to investigate how localised stresses influence the damage mechanism in hybrid contact.
Cyclic contact loading of a gas pressure sintered silicon nitride (GPSN) was investigated. Silicon nitride
disks and tungsten carbide (WC) indenters were tested under different media, initially at ‘‘application relevant”
low contact pressures (4–6 GPa) and further on, to accelerate damage, at high contact pressures
(10–15 GPa). The low load experiments showed various forms of surface damage with no significant difference
between dry and lubricated contact. Whereas, the high load experiments showed different damage
behaviour under unlubricated and lubricated conditions. Unlubricated contact resulted in the
formation of transfer layers and Hertzian cracks on the silicon nitride surface whereas, damage under
lubricated contact was mainly dominated by grain removal and delayed crack formation. Finite element
simulations were carried out to study the stress state under different loading conditions. The FEM results
indicated that the combination of surface tensile and shear stresses predominantly influence the fatigue
damage observed in the experiments rather than fluctuating tensile stresses only.
Permanent Link: http://hdl.handle.net/11104/0276996