WIT Press

C-sphere Strength As An Indicator Of Rolling Contact Performance Of Silicon Nitride


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W. Wang, A. A. Wereszczak & M. Hadfield


Silicon nitride material has been used as a bearing material due to its superior performance against bearing steel. Its successful application as a bearing element leads to the development of other rolling contact applications in the automotive industry, especially the engine manufacturing industry. Its excellent rolling contact performance can make significant savings on warranty costs for engine manufactures. However, the remaining difficulty for the broader application is the high component machining cost. Further understanding of the rolling contact performance of silicon nitride material in relation to its surface integrity will enable engine manufactures to produce components that meet the design requirements while at the same time reduce the machining cost. In the present study, the relationship between the C-sphere strengths of silicon nitride specimens and their rolling contact fatigue life is investigated. The C-sphere test is designed to compare the strengths of three batches of Sintered and Reaction- Bonded Silicon Nitride (SRBSN) specimens with different subsurface quality induced by varying the machining parameters. The rolling contact fatigue (RCF) performance of three batches of SRBSN ball specimens are studied on a modified four ball tester. The results show that the most aggressively machined specimens have the weakest C-sphere strength and the shortest RCF life. This positive relationship can give component manufactures a valuable reference when they make selections of candidate material and finishing standards. Keywords: ceramics, silicon nitride, flexure strength, rolling contact.


ceramics, silicon nitride, flexure strength, rolling contact.