Failure mechanisms of a hydrogenated amorphous carbon coating in load-scanning tests

► First FIB-assisted microstructural study of failure of a-C:H in load-scanning tests ► In sliding against steel (pressure 1-3 GPa), failure is initiated by steel transfer. ► Sites of adhered steel are the source of tensile cracks and further coating failure. ► Coating defects are not responsible for overall mechanical coating failure. ► For a-C:H sliding against a-C:H, at equal pressure, there is no coating failure.