Semi-interpenetrating network composites containing 40 vol.% ceramics (5Al 2 O 3 Á8SiO 2 ) and 60 vol.% Al-alloy were fabricated in place of cast iron available for automotive brake rotors. The friction and wear performances of brake pads dry sliding against the composites were measured using a SRV testing machine. The test procedures include friction fade and recovery, load sensitivity at 100 and 250°C, and wear. The friction was found to increase first and then decrease with increasing temperature, followed by the inverse recovery upon cooling. Wear showed an incremental tendency over a wide temperature range. For loads from 40 to 160 N, the friction decreased at 100 and 250°C. At load below 128 N, the former friction was inferior to the latter while at load above 128 N the friction exhibited an inverse tendency. Wear mildly increased with load at 100°C and decreased dramatically at 250°C. SEM and EDS investigations revealed that the worn pad surfaces at 250°C were covered by more tribofilms, including more coke and graphite with frictionreducing action as well as fewer compounds (corresponding to Si and Al) with friction-increasing action in comparison with those at 100°C. The compression of the tribofilms contributed to a large decrease in the friction and wear with increasing load. However, at 100°C E-glass fibers exposed at the worn surfaces inhibited the excessive wear of the pad despite lack of more tribofilms. Their glossy surfaces decreased the friction. The proposed friction models explain some friction and wear behaviour better.

Semi-interpenetrating network composite containing 33 vol% ceramics (5Al 2 O 3 Á8SiO 2 ) and 67 vol% Alalloy dry sliding against Cr12 cold-work die steel was measured on a SRV4 testing machine. The test procedures include the load sensitivities of the friction and wear at 70°C and 270°C. Test results show that the friction and wear decreased with the increase of load, whereas the specific energy conversion per countermaterial surface unit increased. The friction level and the specific energy conversion at 70°C were superior to those at 270°C. Scanning electron microscopy and energy dispersive X-ray spectroscopy analysis revealed at 270°C the existence of the thicker tribofilms and, with them, more Fe oxides and less Al oxide at the worn composite surfaces in comparison with those at 70°C. A good accordance was obtained between test and analysis results.