High-speed tribological properties of some Al/SiCp composites:: II.: Wear mechanisms

The high-speed frictional and wear-rate characteristics (up to 29 m s(-1)) of four Al/SiCp composites have been described earlier (Kwok JKM, Lim SC, High-speed tribological properties of some Al/SiCp composites: I. Frictional and wear-rate characteristics. Composite Science and Technology, 1999;59(1):55-63). This paper documents our investigation into the various mechanisms of wear which are observed to operate under this same range of sliding conditions when the same four composites, two fabricated inhouse by a powder metallurgy route incorporating mechanical alloying and two sourced commercially, were tested. Five dominant mechanisms have been found, viz (1) abrasive and delamination wear; (2) a combination of abrasion, delamination, adhesion and melting; (3) melt wear; (4) severe adhesion and (5) severe melting. The regions of dominance of the various mechanisms are also presented in terms of the applied load and sliding speed used. It is found that the size of the particulate SiC reinforcement phase controls the high-speed wear resistance of the composites tested; massive wear will occur if the particles are smaller than a threshold value. Al/SiCp composites with small SiC particles are therefore more suitable for lower-speed applications. (C) 1999 Elsevier Science Ltd. All rights reserved.