Effect of Seawater on the Fatigue Life and Failure Distribution of Flood-Lubricated Angular Contact Ball Bearings

Reductions in rolling contact fatigue life as high as 80 percent were observed during flood-lubricated angular-contact ball bearing studies when 1 percent by volume of seawater was added to various lubricants as a contaminant. The lubricants investigated were of different chemical and physical classes and included mineral oils, triaryl phosphate, and two recently developed mineral-oil-base sea-water-emulsifying hydraulic fluids of different viscosities. A shift in failure distribution, from ball failures to inner and outer race failures, is observed when seawater is added. It is proposed that the inner and outer race, because of their anisotropic fiber orientation, are affected to a greater extent by the presence of water than are the rolling elements (balls). Some of the lubricant and system properties affecting fatigue life and failure distribution are: (a) Amount of seawater; (b) Nature of the seawater-lubricant system (dissolved or free seawater); (c) Lubricant viscosity; and (d) Elasto-hydrodynamic film parameter.