Hydrogen assisted rolling contact fatigue due to lubricant degradation and formation of white etching areas

RCF tests were conducted on bearings lubricated with three different lubricants: a gearbox oil, a MAC fluid and PFPE oil. The decomposition of the MAC fluid and PFPE was investigated by FTIR and NMR. Gearbox oil tests showed flaking and networks of subsurface cracks with partial intercrystalline crack growth. Cross-sectional analysis revealed the formation of WEAs. FEM correlated the damage with stress fields. The results of the MAC lubricated tests showed surface flaking and intercrystalline crack growth in the subsurface. The PFPE lubricated bearings showed no signs of hydrogen induced damage. Post-experimental hydrogen analysis of the bearings indicated an increased hydrogen concentration in the samples lubricated with the gearbox oil and MAC compared to those lubricated with PFPE.