How to choose "zinc containing" and "ash free" antiwear hydraulic oil?
October 27, 2022
The antiwear hydraulic oil is developed from antirust and antioxygen hydraulic oil, which has good antirust, antioxygen and excellent antiwear properties. The composition of antiwear hydraulic oil is relatively complex. In addition to antirust and antioxidant, antiwear agent, extreme pressure additive, Metal Deactivator, demulsifier and Antifoam Additive are also added.
From the composition of anti-wear agent, anti-wear hydraulic oil can be divided into two types: 1. Zinc containing antiwear hydraulic oil with zinc dialkyl dithiophosphate (ZDDP) as the main agent. 2. Ash free (metal salt free) anti-wear hydraulic oil. For decades, zinc dialkyldithiophosphate (ZDDP) generated by chemical reaction between zinc oxide and organic thiophosphoric acid has been a key additive component in hydraulic oil and most lubricating oils. ZDDP is a multifunctional additive with good anti-oxidation, anti-corrosion and anti-wear effects. It is widely used in various lubricants such as internal combustion engine oil, hydraulic oil and grease. However, in the actual application process, some hydraulic systems contain silver and copper components. If zinc containing anti-wear hydraulic oil is used, it will corrode silver and copper. At this time, ash free anti-wear hydraulic oil should be selected.
Comparison between zinc containing and ash free anti-wear hydraulic oils: Anti wear hydraulic oil is generally divided into zinc containing type (or ash containing type) and ash free type: ⑴ Zinc containing anti-wear hydraulic oil This kind of oil is called ashy type because it will retain zinc oxide ash after burning because of the addition of zinc containing antiwear agent. In addition, those whose zinc content in oil is lower than 0.07% are usually called low zinc type; Those whose zinc content is higher than 0.07% are also called high zinc type. ⑵ Ash free anti-wear hydraulic oil This type of oil does not contain zinc containing anti-wear additives, nor other metal element additives. Therefore, there is no residual metal oxide ash after combustion, so it is called ash free type. Because ZDDP has many important functions at the same time, if ZDDP is not used, a variety of other additives must be used, which increases the cost of lubricating oil on the one hand, and on the other hand, the use effect may not be ideal. Therefore, ZDDP is still the mainstream of hydraulic oil additives. If the system does not contain silver or copper components and is not subject to environmental restrictions, zinc containing anti-wear hydraulic oil is still the preferred working medium for hydraulic systems, regardless of cost or performance.
