Friction behavior of co-continuous alumina/aluminum composites with and without SiC reinforcement

Co-continuous alumina/aluminum composite materials with excellent physical and mechanical properties offer great potentials for lightweight, wear resi stant, and high-temperature applications. Composite materials prepared from a liquid-phase displacement reaction, present a unique microstructure in w hich each phase is a continuous network penetrated by the network of the ot her constituent. The frictional and wear effects of adding SiC particulate to the co-continuous composite, as well as the application Of MoS2 coatings were examined. Pin-on-disc experiments were performed between 440C stainle ss steel balls and composite disc samples of alumina/aluminum at 0.2 m/s sl iding velocity, with loads of 0.25 and 0.75 N. Microstructural analysis of the composites, wear scar analysis on the composite discs, and material tra nsfer to the steel balls were examined using a scanning electron microscope equipped with an energy-dispersive X-ray spectroscope. The coefficients of friction obtained from the Al2O3/Al composites with and without the SiC pa rticulate reinforcements were correspondingly 0.9 and 0.7 at 60 m sliding d istance. Transfer of aluminum to the steel counterface was not observed and the debris consisted mostly of iron oxide for all tests without the MoS2 c oatings. The friction coefficients dropped to 0.1 when the composite surfac e was burnished with a MoS2 coating. The SiC particulate-reinforced Al2O3/A l ONNEX composites showed higher wear resistance and caused a lower wear ra te on the steel counterface than the unreinforced Al2O3/Al ONNEX composite. (C) 2001 Elsevier Science B.V. All rights reserved.