THE INFLUENCE OF HUMIDITY AND THE ROLE OF DEBRIS IN THE UNLUBRICATED WEAR OF DUCTILE CAST-IRON AGAINST ALUMINA

The unlubricated wear of ductile cast iron sliding against an alumina counterbody under mild pin-on-disc testing conditions was studied. Wear plots showing the evolution of wear coefficient with normal load, sliding velocity and humidity have been established. The evolution of the wear coefficient as well as metallographic observations revealed a three stage oxidational wear mechanism. A decrease in humidity resulted in an increase of wear coefficient, mainly owing to abrasive debris behaviour. The removal of wear debris during testing helped in understanding its role in the wear process of ductile cast iron. This role appeared to be both detrimental under dry and beneficial under humid conditions respectively.