Cavitation and rolling wear in silicon nitride

Rolling contact and cavitation testing were integrated in a testing methodology to study their combined effect on silicon nitride rolling elements. This testing methodology is well suited to perform controlled cavitation and rolling contact experiments. Acoustic cavitation method and a rotary tribometer were utilized to achieve this objective. Silicon nitride degradation initiated with the formation of blisters in rolling contact. This blisters underwent cracking in the subsequent testing, thereby allowing the lubricant to squeeze in due to rolling contact. Erosion pits formed and their density increased along with their growth by detaching grains and bridging into adjacent pits. As the erosion severity in the rolling contact increased the material eventually failed in a short period of time with respect to the testing conditions. The effect of cavitation and rolling contact parameters on material damage is detailed in this paper thereby allowing an evaluation of material systems for cavitation-rolling contact fatigue (RCF) conditions.