Effect of a Rising R-Curve on the Sliding Wear of Silicon-Disilicide In Situ Composites

TitleEffect of a Rising R-Curve on the Sliding Wear of Silicon-Disilicide In Situ Composites
Publication TypeJournal Article
Year of Publication2012
AuthorsFischer, DS, Schuh, CA
JournalJournal of the American Ceramic Society
Pagination1406 - 1413
Date Published2012/04//

This study investigates the tribological behavior of a new class of silicon-disilicide (Si-(Cr,V)Si-2) in situ composites which display eutectic microstructures comprising a Si matrix and reinforcing (Cr,V)Si-2 disilicide phase. Dry, room temperature ball-on-disk tests carried out at various loads (W = 1-6 N) showed that the specific wear rates of the Si-(Cr,V)Si-2 composites (k(a) approximate to 10(-5) mm(3)/Nm) were about an order of magnitude lower than that of unalloyed Si (k(a) approximate to 10(-4) mm(3)/Nm) in the wear regime dominated by lateral cracking. Microscopic analysis of the wear tracks, as well as observations from indentation experiments, revealed that the improved wear resistance of the Si-(Cr,V)Si-2 composites at higher loads was due to the activation of crack deflection and bridging toughening mechanisms during the wear process, which results in a rise in the apparent composite fracture toughness with increasing crack size (i.e., a rising R-curve behavior). Analysis of the wear test data in the context of a lateral fracture wear model demonstrates that the enhanced short-crack response of the Si-(Cr,V)Si-2 composites during sliding wear can indeed be explained by the incorporation of a sharply rising R-curve relation for the composite fracture toughness.