WEAR MODE MAP OF CERAMICS

On the basis of in situ observations of wear processes in a scanning electron microscope, the mechanical wear mechanisms for ceramics are classified into three microscopic wear modes: flake formation, powder formation and ploughing. The condition for the occurrence of each wear mode is analysed theoretically using linear fracture mechanics. On the basis of this analysis, two wear mode maps for ceramics are introduced by using the dimensionless parameters S(c), S(c)* and the coefficient of friction-mu, where S(c) is a function of maximum hertzian contact pressure, maximum surface roughness and fracture toughness and S(c)* is a function of hardness, maximum surface roughness and fracture toughness. The wear mode map using S(c) and mu shows the possible region of flake formation. The wear mode map using S(c)* and mu shows the possible regions of powder formation and ploughing. Experimental results for several ceramics under different experimental conditions agree well with the above wear mode maps for ceramics.