Effect of Free Water on Film Forming Characteristics of Lubricating Oil in Point Contact Zone

As a main source of oil contamination, water is one of the most importance reasons of failures and life reduction of the lubricant and the mechanical system. Up to now, there is few research about the direct observation and research on the impact of water contamination on the lubrication properties of the contact zone, and the researchers only can infer the possible failure mechanism by the contact worn surface. Therefore, it is important to carry out the research on the influence of the water on the film forming ability of the contact. It helps us to understand the mechanisms of the water induced mechanical failure and to provide theoretical guidance of the water contamination protection work. The influence of water on the film thickness under different lubricating condition has been studied and the dimensionless criterion for the influence of water on the film thickness has been proposed. It is found that the scour and emulsification of free water on the oil pool and the track were the main reasons for the reduction of the film thickness and the oil re-flow. The failure of the lubrication of the contact due to free water in early stage is testified.