Septem Wear Behavior of A//Al-Zr Laminated Composites 1.0 v=005m/s 0.8 0.6 04 008c V=0.10m/s 0.8 0.6 v=0.15ms 0.8 0.6 AAZ 0.4 40 60 80 100 120 140 160 Applied load, N Fig. 5. Mean values of the friction coefficients measured on the various materials for the different experimental conditions. oy cracking of the grains at the early stage of the process. This equal to the local fracture toughness K e The presence of com- ascertainment suggests that microcracking is the main wear mech ressive residual stresses increases the rent surface fracture anism active under the described experimental conditions. When toughness and, since it opposes the tensile stress generated in the the wear mechanism is associated with the formation of surface wake of the sliding contact, it prevents the formation and propa cracks, the laminated composite A/AZ always exhibits(except gation of cracks. under a load of 50 N and sliding speed of 0. 10 m/s)a lower Some cracks were also observed (Fig. 7(a)) in the wear track of pecific wear than the other materials (AA and MA). For a material he A/AZ composite tested at 100 N and 0.05 m/s. However, the with a given flaw size. the critical condition for the onset of severity of the damage caused by this phenomenon was definitely cracking at the surface occurs when the stress intensity factor Kr lower than that observed in the other materials tested under the due to the maximum principal tensile stress (o, max) Is greater or same experimental conditions (Fig. 7(b)) v=005m/s zE0=930 -5 V=0.10m/s ▲…AA 县二 -6 V=0.15ms -5 mild 100 120 Applied load, N Fig. 6. Semilog plot of the disk specific wear of the various materials as a function of the different experimental conditions