Lubricating grease is mainly composed of three parts: thickener, base oil, and additives.
Generally, 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 less than 5%.
l. Base oil
Base oil is the dispersing medium in the grease dispersion system, and it has a great influence on the performance of the grease.
Generally, medium-viscosity and high-viscosity petroleum lubricating oil is used as the base oil for general lubricating greases, and some are used to meet the needs of mechanical lubrication and sealing under harsh conditions, using synthetic lubricating oil as the base oil, such as ester oil and silicone oil. , Poly-olefin oil, etc.
The thickening agent is an important component of the grease. The thickening agent is dispersed in the base oil and forms the structural skeleton of the grease, so that the base oil is absorbed and fixed in the structural skeleton.
The water resistance and heat resistance of grease are mainly determined by the thickener. There are two broad categories of thickeners used in the preparation of greases. Soap-based thickeners (ie fatty acid metal salts) and non-soap-based thickeners (hydrocarbon, inorganic and organic).
Soap base thickeners are divided into three types: single soap base (such as calcium base grease), mixed soap base (such as calcium sodium base grease), and complex soap base (such as complex calcium base grease). 90% of greases are made with soap-based thickeners.
3. Additives and fillers
One type of additive is what lubricating grease needs, called peptizer, which makes the combination of oil and soap more stable, such as glycerin and water.
Once calcium-based grease loses water, its structure is completely destroyed and cannot become fat. For example, glycerin can adjust the consistency of grease in sodium-based grease.
The other type of additives are the same as those in lubricating oils, such as antioxidants, anti-wear and rust inhibitors, but the amount is generally more than that in lubricating oils. Such as phosphate ester, ZDDP, Elco extreme pressure antiwear agent, compounding agent, dropping point enhancer, etc.
Sometimes, in order to improve the ability of grease to resist loss and enhance lubrication, some graphite, molybdenum disulfide and carbon black are often added as fillers.
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