lithium stearate grease is a lithium-based lubricating grease that is used to lubricate friction parts such as automobile hub bearings, chassis and water pump in a temperature range of -30 deg C to 120 deg C. It is a type of high and low-temperature general purpose grease that can be used in a wide variety of applications.
It can be produced by thickening fatty acid soap with low-condensation point mineral oil and adding rust inhibitor and antioxidant. It has excellent lubrication properties and is characterized by good low-temperature performance, high rust resistance, mechanical stability and dropping point.
The fatty acid used to thicken the lithium-based grease can vary from the usual fatty acids used in calcium-based greases, such as linoleic acid, to an uncommon fatty acid called lithium 12-hydroxystearic acid. This fatty acid has been found to be superior for a variety of reasons and is generally preferred by grease manufacturers when compared with other fatty acids.
Some of the advantages of this acid are its webbed fibrous structure which is only visible on a microscopic scale, its smooth texture and its high thickener content by weight ranging from about 10-15 percent. The fatty acid also tends to have a higher viscosity than other fatty acids, which can be an important factor when choosing the proper thickener for a specific application.
Typically, a lithium-based grease is prepared by heating the required fatty acid soap to a temperature of about 250 F. or higher and adding a gel stabilizer such as an aliphatic monohydric alcohol and then cooled to room temperature. Kettle-cooling, a method that has been used to prepare lithium-based greases for some time, is the preferred method of cooling these greases. This method allows a more controlled and uniform cooling process.
