Basic composition of lubricating grease

Lubricating grease is mainly composed of three parts: thickener, base oil and additives. Usually the content of thickener in lubricating grease is about 10%-20%, the content of base oil is about 75%-90%, and the content of additives and fillers is within 5%.

1. Base oil

Base oil is the dispersion medium in the lubricating oil dispersion system, which has a great influence on the performance of lubricating oil. Generally, lubricating greases are mostly made of medium-viscosity and high-viscosity petroleum lubricating oils as base oils, and there is also a point that is suitable for the lubrication and sealing of mechanical equipment operating under harsh conditions. Synthetic lubricating oils are used as base oils, such as ester oils , silicone oil, poly-α-olefin oil, etc.

2. Thickener

Thickener is a key component of lubricating grease. The thickener is dispersed in the base oil and creates the structural framework of the lubricating grease, so that the base oil is adhered and fixed in the structural framework. The water resistance and heat resistance of lubricating grease are mainly determined by the thickener. There are two main types of thickeners used in the preparation of lubricating greases. Soap-based thickeners (i.e. metal salts of fatty acids) and non-soap-based thickeners (hydrocarbon, inorganic and organic).

Soap-based thickeners can be divided into three types: single soap base (such as calcium-based grease), mixed soap base (such as calcium-sodium-based grease), and complex soap base (such as complex calcium-based grease). 90% of lubricating oils are made with soap-based thickeners.

3. Additives and fillers

An additive that is unique to lubricating oils is called a peptizer, which makes the fusion of oil and soap more stable, such as glycerin and water. Once water is lost in calcium-based grease, its structure will be basically destroyed and fat cannot be formed. For example, glycerin can adjust the viscosity of grease in sodium-based grease. Another additive is the same as in lubricating oil, such as anti-oxidation, anti-wear and anti-rust agents, etc., but the amount used is usually more than that in lubricating oil. Such as phosphate ester, ZDDP, Elco extreme pressure antiwear agent, compounding agent, dropping point enhancer, etc. Sometimes, in order to better improve the lubricating grease's ability to resist loss and enhance lubrication, a little graphite, molybdenum disulfide and carbon black are often added as fillers.