Comparison of bentonite grease and lithium complex grease

Greases are broadly classified into soap-based grease and non-soap-based grease. Although the former is most used in industry, the latter also has its application advantages. With the development of society and industry, the requirements for the use of grease in mechanical equipment have become more and more stringent, and high temperature resistance is crucial. There are many soap-based high-temperature greases in China that cannot meet the needs of users. The advantage of non-soap-based high-temperature greases is that they have no dropping point.

Bentonite grease is an important non-soap high-temperature grease, which is widely used in the lubrication of aircraft, automobiles, metallurgical equipment, heavy-duty equipment, etc. In my country, lithium-based grease and high dropping point lithium complex-based grease are still the mainstream, accounting for more than 70% of the total. The output of moisturizing grease is much lower than the world average. The reasons are roughly as follows:

Bentonite grease has poor sensitivity to additives, that is, the additives do not improve its performance too much, and incompatibility will also destroy the structure of the grease.

The mechanical stability of bentonite grease is far inferior to that of lithium complex grease. Research shows that the change rate of cone penetration of lithium complex grease for 00,000 times and 60 times is generally less than 0%; while the change rate of bentonite grease Then it is greater than 20%. After shearing of bentonite grease, the working cone penetration increases greatly, the grease becomes thinner, the oil separation rate increases, and the colloid stability becomes worse. In the final analysis, it is because bentonite grease is incompatible with many additives that its performance is far inferior to lithium complex grease. Therefore, it is also the biggest problem restricting the popularity of bentonite grease.

The characteristics of bentonite grease are as follows:

(1) Organic bentonite does not change like soap-based grease, so bentonite grease has no dropping point, and its high-temperature properties are only determined by the high-temperature resistance of the surfactant. General bentonite grease can be used above 150C.

(2) The low temperature performance of bentonite grease is mainly determined by the low temperature of the selected base oil.

(3) The structural particles of bentonite grease should be more resistant to shearing than soap fibers. However, since bentonite has been treated with surfactants, the mechanical stability of bentonite grease changes with the properties of different surfactants. After being used in rolling bearings for a long time, bentonite grease will easily become thin and flow out. Bentonite grease has poor anti-corrosion properties on metal surfaces, and effective rust inhibitors must be added to improve it.

(5) Bentonite grease: Since the bentonite thickener is firmly combined with the base oil, on the one hand it shows its excellent colloidal stability, on the other hand it shows that the base oil is difficult to enter the friction surface, so the wear resistance and scratch resistance are not very good. Ideal, affecting its use in high-speed rolling bearings.