Synthesis of Zinc Dialkyldithiophosphates as an Additive into Motor Oil and Study of Antioxidant and Antiwear Properties of Them

Considering the progress of tribology and the existence of a wide range of additives in lubricants, proceeding this field of technology is of an outstanding importance. In this study, a kind of antiwear additive and antioxidant, called zinc dialkyldithiophosphate, is investigated. The synthesis of zinc dialkyldithiophosphate is performed in two stages. In the first stage, phosphorus pentasulfide reacts with alcohol to obtain dialkyldithiophosphoric acid. In the second stage, the produced acid is neutralized by zinc oxide and thus the final product is achieved. In this study, six types of products are synthesized with different kinds of alcohol, such as isobutanol, isoamyl alcohol, hexanol, and isooctanol. Infrared spectroscopy is used to detect the structure of the synthesized materials. These materials are mixed with base oil SN 150 and SN 500 to operate oxidation and wear tests. The results are compared with the results obtained from the imported sample. Among all the products synthesized, the best antioxidant and antiwear is the sixth product.