Humidity effect on the critical number of friction cycles for wear particle generation in carbon nitride coatings

Wear particle generation in carbon nitride coatings by a spherical diamond counterpart in repeated sliding contacts has been studied with an emphasis on the effect of relative humidity varying from 0.4 to 80%. An environmental scanning electron microscope (E-SEM), in which a pin-on-disk type apparatus was installed, has in situ provided direct evidence that when and where the wear particle generation do occur. The in situ examination of non-conductive carbon nitride coatings are therefore available free from surface charging with controllable relative humidity and a sliding speed of 50 mm/s varying normal load from 10 to 250 mN.