What phenomenon occurs when the lubricant cannot adequately separate water?

Emulsification occurs when two immiscible liquids, such as oil and water, are combined in a way that allows them to mix temporarily. In the context of lubricants, this phenomenon can happen when the lubricant is unable to effectively separate water from itself, leading to the formation of a stable mixture or emulsion. This situation is problematic because emulsification can hinder the lubricant's ability to perform its intended function, such as providing proper lubrication and preventing wear on engine components. An emulsion may cause increased corrosion, reduced lubricating properties, and difficulties in separating water from the system, ultimately leading to reduced efficiency and potential damage.

The other concepts mentioned, like demulsibility, viscosity breakdown, and thermal degradation, involve different aspects of lubricant performance and stability. Demulsibility refers to the ability of a lubricant to separate from water, while viscosity breakdown involves the reduction of a lubricant's thickness or resistance to flow, usually due to thermal conditions or contamination. Thermal degradation relates to the deterioration of a lubricant due to heat, which can affect its properties but does not directly describe the inability to separate water.