Rolling Fatigue Life of Silicon Nitride Ceramic Balls

질화규소 세라믹볼의 구름피로수명

  • 최인혁 (FAG한화베어링(주)) ;
  • 박창남 (FAG한화베어링(주)) ;
  • 최헌진 (한국과학기술연구원 복합기능세라믹스센터) ;
  • 이준근 (한국과학기술연구원 복합기능세라믹스센터) ;
  • 신동우 (경상대학교 재료공학부, 첨단소재연구소)
  • Published : 1999.06.01

Abstract

The rolling fatigue lives (RFL) of five kinds of silicon nitride balls were investigated. Four kinds of Si$_3$N$_4$ balls were fabricated using different raw materials, sintering aids and sintering conditions, Commercially available Si3N4 ball was also studied for comparison. All the balls were finished up to the dimensional accuracy of Grade 10 defined in KS B 2001 (Steel Balls for Ball Bearings) with a size of 9.525mm. RFL tests were then conducted under the initial theoretical maximum contact stress 6.38 GPa and the spindle speed 10,000 rpm. Gear oil was provided by oiled race as lubricant. The results of RFL test indicated the prerequisitic conditions for the long rolling life of Si$_3$N$_4$ball : (1) the high density, (2) mjcrostructures consisted of small uniformly distributed grains, (3) little glassy phase in grainboundary, and (4) little crystalline phase and secondary phase that induces residual thermal stress due to the differences of thermal expansion coefficient with Si$_3$N$_4$Phase.

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