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Effect of Relative Humidity on Repetitive Impact Behavior of Machined Silicon Nitride
Author(s) -
Srinivasan Sreeram R.,
Blau Peter J.
Publication year - 1994
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.1151-2916.1994.tb05349.x
Subject(s) - materials science , relative humidity , silicon nitride , humidity , composite material , silicon , durability , fracture (geology) , combustion , nitride , water vapor , metallurgy , layer (electronics) , chemistry , physics , organic chemistry , thermodynamics
Silicon nitride is a promising candidate material to replace metallic valves in internal combustion engines. Its attractive mechanical properties relative to conventional alloys are expected to lead to reduced valve wear. As valves operate under combined conditions of impact and sliding contact, the durability of Si 3 N 4 under a repetitive 45° impact was studied to assess the performance of these materials as valves. A significant effect of relative humidity on the impact behavior of Si 3 N 4 was noticed. Humid conditions resulted in a significant increase in impact wear resistance. This increase appears to be related to the differences in fracture modes under humid versus dry conditions. A possible mechanism for the observed humidity effects in Si 3 N 4 is advanced to explain the change in fracture modes. Increased impact resistance is expected to be a useful property for valve materials, as engine atmospheres contain significant amounts of water vapor resulting from the combustion reactions.