Wear behaviour of interpenetrating alumina–copper composites

► Increasing copper fraction increased the wear rate, except where a tribolayer formed or where the alumina grains were weakly bonded. ► Increasing the copper ligament diameter decreased the wear rate. ► The grain size of alumina affected the wear behaviour. ► Composites with the coarsest copper network had the highest wear resistance, probably due to the higher heat conductivity and fracture toughness. The wear behaviour of a variety of alumina–copper interpenetrating composites was tested as a function of copper ligament diameter and volume fraction of copper. The wear mechanisms of pure copper and pure alumina were adhesive and abrasive wear, respectively. In the composites with 1 μm, 5 μm and 15 μm copper ligament diameters, the wear mechanism was a mixture of adhesive and oxidative; in composites with a 30 μm copper ligament diameter a mixture of abrasive and oxidative. Increasing the amount of copper decreased hardness and thus increased wear, except where cyclic tribolayer behaviour occurred or where the alumina grains were weakly bonded. Increasing the copper ligament diameter decreased wear, although this trend was only clear under a load of 20 N. The composites with the highest wear resistance had the highest copper ligament diameter of 30 μm. This was probably due to the higher heat conductivity and fracture toughness caused by the coarse, fibrous copper network replicating the wool felt used to produce it. This was possibly also because these composites had the smallest alumina grain size.