Fig. 6 summarizes all the results above. It shows the normalized distributions for the nitrogen ion profile, the hardness profile, and wear rate as a function of depth. The hardness profile seems to peak at about the same spot as the nitrogen concentration profile, but it is difficult to determine this precisely, due to the inability of the hardness tests to provide useful data at depths below about 25 nm. The wear rate exhibits a somewhat more complex distribution, primarily due to the break-in behavior discussed earlier. Discounting this, the wear rate is shown to be relatively small in the implanted layer (to a depth of approximately 110 nm), before increasing markedly at greater depths. This implies that the wear rate is low until the wear depth exceeds the deepest penetration point of the nitrogen ions. This is consistent with the assumption that the property changes correspond to the region in which the nitrogen ions are deposited.