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Effect of a Rising R‐Curve on the Sliding Wear of Silicon‐Disilicide In Situ Composites
Author(s) -
Fischer David S.,
Schuh Christopher A.
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2012.05075.x
Subject(s) - materials science , composite material , fracture toughness , eutectic system , composite number , tribology , microstructure , molybdenum disilicide , silicon , indentation , cracking , toughness , metallurgy , molybdenum
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 ≈10 −5 mm 3 /Nm) were about an order of magnitude lower than that of unalloyed Si ( k a ≈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.