抄録
Wear processes of Co/Cu multilayers whose component layer thickness h ranged from 10 nm to 250 nm have been investigated. The Co/Cu multilayers were fabricated on polycrystalline copper substrates using electrodeposition method. Sliding wear tests on the Co/Cu multilayers were carried out in a ball-on-disk type machine in air at room temperature. Wear resistance of the multilayers depended strongly on component layer thickness h: a lost thickness of the multilayer of h=10 nm was shorter than that of h=250 nm by a factor of 5. From surface observation of the worn multilayer of h=100 nm, surface cracks were detected along lines corresponding to grain boundaries of the copper substrate. The wear process of the multilayers having thicker layers was certainly promoted by these surface cracks. On the other hand, in the worn multilayer of h=20 nm, the crack formation was almost suppressed. Accordingly, the layer thickness dependence of the wear resistance could be related to the resistance to surface cracking.
