Rolling wear of silicon nitride bearing materials with refrigerant lubrication
Start date: 7 December 2005
Publisher: Institution of Mechanical Engineers
t This paper presents the experimental results of wear in rolling hybrid ceramic (Si3N4) bearing material with hydrocarbon HC (R600a, CH (CH3)3, 2-methyl propane/isobutene) refrigerant lubricants. Failure modes and rolling wear performance of these ceramic materials in HC refrigerant environment were analysed. During rolling contact fatigue testing the secondary crack initiation occurs at the maximum tensile region of the contact path. The crack initiation of takes place as the residual stresses are relieved with increase in rolling contact stress cycles. The crack is subsequently propagated in the contact circle. The decrease in residual stress at the contact edges causes a gradual decrease in the maximum tensile stress circle. The original contact circle stress distribution is changed. Gaseous phase of the refrigerant results in severe wear during rolling contact fatigue of hybrid ceramic/steel contact.
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Authors: Khan, Z.
Journal: Society of Tribologists and Lubrication Engineers - 2008 Annual Meeting and Exhibition, Extended Abstracts
This paper presents the experimental results of wear in rolling hybrid ceramic (Si3N4) bearing material with hydrocarbon HC (R600a, CH(CH3)3,2-methyl propane/isobutane) refrigerant lubricants. A novel pressurised chamber was designed to construct the special purpose rig to achieve saturated liquid state of the refrigerant as fluid for the rolling contact fatigue experiments. High Speed four ball Rotary Tribometer was used for rolling contact fatigue tests. This paper presents an experimental study of the influence of the HC (R600a) refrigerant environment on rolling wear of the silicon nitride/steel elements and shows various modes of failures. Rolling fatigue test methods were used to measure the wear performance of silicon nitride/steel bearing materials. Light microscopy was used to examine the material surface before carrying the tests. Light microscopy was employed for surface examination during and after tests. Scanning Electron Microscopy (SEM) was used for imaging. Failure modes and rolling wear performance for these ceramic materials in HC refrigerant environment were analysed. Experimental results are presented in this paper.