With the development of industrial technology, high speed, high performance, high automation, high efficiency and long life required by modern equipment, it is difficult to meet the lubrication of mineral oil alone. Adding a small amount of other substances to the lubricating material can improve its performance and give it new properties. These substances are called additives for lubricating oils.

Adding different additives to the oil is the most economical and effective means of improving oil quality. Generally speaking, the quality of lubricating oil often depends on the variety and quality of additives. Therefore, the development and use of additives has become an important way to rationally and effectively utilize resources, improve equipment performance and save energy.

Lubricating oil additives can be divided into clean dispersing agents, anti-oxidant anti-corrosive agents, extreme pressure anti-wear agents, oil-based agents and friction modifiers, antioxidants and metal deactivators, viscosity index improvers, rust inhibitors, and Grouping of coagulants, anti-foaming agents, etc., In the past two weeks, we have talked about part of the mechanism of action of additives. Next we continue to introduce the mechanism of action of other commonly used lubricant additives.

Rust inhibitor

The role of the rust inhibitor is to form a strong adsorption film on the metal surface to inhibit the contact of oxygen and water, especially water, on the metal surface so that the metal does not rust. As a rust inhibitor for petroleum additives, it is necessary to have sufficient adsorptivity to the metal and solubility in oil. Therefore, the rust inhibitors are composed of a strong polar group and a suitable oleophilic group. At present, the following types are widely used and have better effects: sulfonate (sodium sulfonate, sodium sulfonate and sulfonate), Carboxylic acids and salts thereof (dodecenylsuccinic acid, zinc naphthenate, N-oleoyl sarcosine octadecyl salt), organic phosphates, imidazoline salts, ester type rust inhibitor (lanolin and lanolin soap, benzene-60 or 80, oxidized petroleum grease), heterocyclic compound (benzotriazole), Organic amines and so on.

The water-soluble rust inhibitors mainly include sodium nitrite, potassium dichromate, trisodium phosphate, diammonium hydrogen phosphate, sodium benzoate, triethanolamine and the like. Rust inhibitors are mainly used in industrial lubricating oils and metal processing cooling lubricants, metal protective oils, etc.

Anti-foaming agent

Lubricating oil base oil will still retain a small amount of polar substances after refining, and as the lubricating oil uses various additives to meet the high performance requirements of various mechanical equipment, it will cause foaming in the circulating lubrication system, It not only affects the pumping of lubricating oil, but also destroys the strength and stability of the oil film, causing undue wear and tear, or making the machine unable to operate normally. The phenomenon such as oil cut, gas resistance and sintering will continue to occur.

The antifoaming agent acts to inhibit the generation of foam, so as not to form a stable foam, which can be adsorbed on the bubble film to form an unstable film, thereby achieving the purpose of destroying the foam. The most commonly used antifoaming agent is a methyl silicone oil antifoaming agent. It is insoluble in oil and is distributed in oil by a colloid mill or the like in a highly dispersed state. It is generally used in an amount of from 1 to 100 ppm. There is also a non-silicon antifoaming agent which is a polyacrylate type polymeric ester. Compared with silicone oil, it can effectively improve the air release of oil.