Surface strength of silicon nitride in relation to rolling contact performance measured on ball-on-rod and modified four-ball tests

Wei Wang, Mark Hadfield, Andrew A. Wereszczak

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Silicon nitride (Si3N4) has been used in various rolling contact applications in turbomachinery, automotive and power industry. It is favoured to replace conventional steel due to its low density, low friction, corrosion resistance and good performance under extreme condition. However, a major limitation of its wider application is its high material and machining cost, especially the cost associated with the finishing process. In the present study, a low cost sintered and reaction bonded silicon nitride (SRBSN) is used to study the surface machining effects on its rolling contact performance. Attempt has been made to link the surface strengths of Si3N4 derived from half-rod and C-sphere flexure strength specimens to the rolling contact lifetimes of Si3N4 rod and ball specimens. The rolling contact fatigue tests are carried out on ball-on-rod and modified four ball machines. Three types of surfaces with coarse, fine and conventional finishing conditions are examined. Flexure strength tests on half-rod and C-sphere show an increasing surface strength from specimens with coarse, fine to conventionally machined conditions. During rolling contact fatigue test of as-machined specimens, there are no failures observed on both ball-on-rod and four ball tests after 100 million stress cycles. However, there is a trend of decreasing wear volumes measured on the contact path of rods and balls with coarse, fine and conventional conditions. In four ball test, spall failures are observed on pre-crack specimens. There is a trend of increasing rolling contact fatigue lifetime from pre-cracked specimens with coarse, fine to conventional machining conditions.

Original languageEnglish
Pages (from-to)423-432
Number of pages10
JournalTribology International
Volume43
Issue number1-2
DOIs
StatePublished - Jan 2010

Funding

The authors would like to thank US Department of Energy Heavy Duty Diesel Engine Material Programme for funding this research through Oak Ridge National Laboratory.

Keywords

  • Rolling contact fatigue
  • Silicon nitride
  • Surface strength

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