What are hydraulic oil additives?
1、Oiliness Agent
Oiliness agent is a substance with strong polarity. Under low temperature and pressure, it can adsorb to the metal surface to form a strong adsorption film, prevent direct contact between metals, improve the strength of the oil film, and reduce the friction and wear of metals.
In hydraulic oil, commonly used oiliness agents include: oleic acid, sulfurized whale oil, sulfurized cottonseed oil, sulfurized olefin cottonseed oil, dimer acid , etc.
2、Antiwear Agents
Under high friction temperature, the decomposition products of anti-wear agents react with the metal surface to produce a low shear stress and low melting point compound film to prevent the bite or welding of the contact surface. The resulting plastic deformation fills the uneven parts between the friction surfaces, increases the contact surface, reduces pressure, and reduces wear.
Anti-wear agents usually contain sulfur, phosphorus and chlorine, and their compounds have their own characteristics. Anti-wear agents containing sulfide react with iron to form an iron sulfide film under high temperature friction conditions, which plays an anti-wear role; anti-wear agents containing phosphorus, under not too high temperature and mild friction conditions, the products of the thermal decomposition of phosphate interact with steel to form a low melting point, high plasticity phosphate mixture, which plays an anti-wear role; anti-wear agents containing chlorine, under extreme pressure conditions, produce iron chloride film, which is a layered structure with a small friction coefficient, easy shearing, and good lubrication.
In hydraulic oil, commonly used anti-wear agents include: zinc dialkyl dithiophosphate (T203), trimethylol phosphate (T306), thiophosphate (T303°), sulfided olefin (T321), chlorinated paraffin (T301), etc.
3、Tackifier
Thickener is an additive that improves the viscosity-temperature properties of hydraulic oil and increases the viscosity index. This is a type of high molecular polymer that shrinks and curls into tight small balls in the oil at low temperatures, which has little effect on low-temperature viscosity. At high temperatures, it swells and stretches in the oil, increasing viscosity and improving viscosity-temperature properties.
Commonly used thickeners in hydraulic oil include: polyisobutylene (PIB), ethylene-propylene copolymer (J0010), polymethacrylate (T602HB), etc.
4、Antifoaming agent
Antifoaming agents are substances that can reduce the stability of foam adsorption films and shorten the existence time of foam. Adding antifoaming additives to hydraulic oil can reduce surface tension, allowing bubbles to quickly overflow the oil surface, thereby eliminating bubbles.
In hydraulic oil, commonly used antifoaming agents include: silicon-containing defoaming agents (AF-3), silicon-free defoaming agents (AF-5), etc.
5、Pour Point Depressant
Pour point depressants are a type of additive that can inhibit the formation of paraffin in oil into network crystals, lower the pour point, and maintain the fluidity of the oil. This product changes the crystal shape and size of paraffin by adsorbing or forming eutectics on the surface of paraffin crystals, thereby lowering the pour point of the oil.
Commonly used pour point depressants include: alkyl naphthalene, polymethacrylate (T602), alpha olefin copolymers, and in hydraulic oil, "ethylene vinyl acetate" ester copolymers, etc.
6、Antioxidants
Antioxidants are a type of additive that is easily oxidized and can form a complex film on the metal surface, isolating it from contact with oxygen and other corrosive substances, and preventing the metal from catalyzing the oxidation of the oil and the oil from corroding the metal.
Generally, several antioxidant additives are used in combination to achieve better anti-gas effects. For example, the combination of sulfide and aromatic hydrocarbons will produce a synergistic effect; the combination of free radical terminator and peroxide decomposer also has a significant synergistic effect.
In hydraulic oil, commonly used antioxidants include: 2,6-di-tert-butyl-p-cresol (T501), N-phenyl-a-naphthylamine, sulfided isobutylene (T321), dialkyl dithiocarbamate, aromatic hydrocarbons, bisphenol, etc.
7、Rust inhibitor
Rust inhibitors are a class of polar compounds that can form a strong water-increasing adsorption film on the metal surface to prevent the metal from rusting.
In hydraulic oil, commonly used rust inhibitors include: dodecenyl succinic acid, barium dinonyl naphthalene sulfonate, dodecenyl succinate of heptadecenyl imidazoline etc.
8、Antifungal agent
Antifungal agents can prevent and inhibit the formation of mold in emulsified oil.
In hydraulic oil, commonly used antifungal agents include: phenolic compounds and formaldehyde compounds.
9、Demulsifier
Demulsifiers are substances that can separate or settle water and oil.
In hydraulic oil, commonly used demulsifiers include: polyether polymer compounds and various polymers of ethylene oxide and propylene oxide.
10、Metal passivator
Metal passivators are a type of additive that can protect non-ferrous metals, especially copper surface corrosion. The agent can also increase the oil's antioxidant properties and inhibit and passivate acidic substances from corroding copper.
There are two types of Jinwu passivators used in hydraulic oils: one is a film-forming passivator that can form a film with the copper surface to prevent corrosion by acid-active sulfides and corrosive extreme pressure agents. Commonly used ones include benzotriamine azole, and the other is an active sulfur scavenger that reacts with active sulfides to generate low-corrosive or non-corrosive polysulfide compounds.
