Extended Data Figure 6: Wear volumes, calculated using three-dimensional optical profilometry.
a, Three-dimensional representation of the volume loss of three steel balls (one coated with MoNx–Cu and two uncoated, in different oils) on the basis of flattening of the spherical caps of the steel balls. There is very little wear, with only a few scratches, on the ball coated with MoNx–Cu and tested in PAO 10. b, Wear volume calculations, based on the profilometry in a, and compared with geometrical calculations based on the wear scar diameter. The wear volumes calculated using the two techniques are comparable, except in the case of MoNx–Cu, where the diameter represents only the polished Hertzian contact area. 7.35E−15 is 7.35 × 10−15, and so on.
