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Friction and Wear Properties of Si 3 N 4 /Carbon Fiber Composites with Aligned Microstructure
Author(s) -
Hyuga Hideki,
Jones Mark I.,
Hirao Kiyoshi,
Yamauchi Yukihiko
Publication year - 2005
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.1551-2916.2005.00283.x
Subject(s) - materials science , composite material , microstructure , fiber , perpendicular , composite number , silicon nitride , grain size , layer (electronics) , geometry , mathematics
The friction and wear properties of silicon nitride/carbon fiber composites have been assessed and compared with monolithic Si 3 N 4 . Three different types of composites have been produced; one in which both the Si 3 N 4 grains and the carbon fibers were aligned, one in which only the fibers had alignment, and a third where both the grains and fibers had random orientation. The friction coefficients of all of the composites, following running in, were around 0.2–0.3, typically less than one‐third of that of the monolithic material. However there was no significant difference in friction coefficient between the three different types of composite. The specific wear rates of all the materials decreased with sliding distance and those of the composites were lower than the monolithic material. Among the composites, the wear rate of the one with aligned fibers in a randomly oriented Si 3 N 4 matrix showed no dependence on sliding direction relative to the fiber alignment, and the specific wear rates of these samples were similar to that of the randomly oriented fiber composite, indicating little effect of fiber alignment alone on the wear properties under the present testing conditions. However, the specific wear rate of the composite with both fiber and grain alignment showed directional dependence. Grain cracking was observed perpendicular to the sliding direction, and the Spara specimen, in which the sliding direction was parallel to the Si 3 N 4 grain alignment, showed higher wear rates than the Sperp and N samples of this composite. Such cracks are perpendicular to the major axis of the grains in the Spara sample and are thought to lead to easier removal of grains following their cracking under the tensile stresses induced particularly during the running in period.