The classical lubrication theory suggests the use of oil to reduce wear by the development of a thin separating lubricating film. However, the trends in the industry dictate miniaturization of the mechanical devices with a concurrent increase in the load carrying capacity. This in turn brings the surfaces to a closer contact and increases wear. Anti-wear additives are widely used to prevent excessive wear of the materials in these situations.
One of the most effective anti-wear additives used in engine oil is Zinc Dialkyl Dithiophosphate (ZDDP). It is well known, that ZDDP generates a tribofilm on the surface of the material and protects them from wear. While being effective, it is also environmentally hazardous and the new regulations restrict the use of ZDDP in oils and therefore, there is an urgent need for the substitute. In order to create the new anti-wear additive, it is necessary to understand the mechanisms of the effective performance of the ZDDP and particularly to answer the question why ZDDP is wear resistant?
Researchers from University of Leeds, UK, and SKF Research and Engineering Centre, The Netherlands, recently reported a detailed study of the ZDDP tribofilm generation and removal. The researchers developed a novel experimental method and investigated the durability of ZDDP tribofilm at various conditions by measuring the tribofilm thickness.
“This is interesting in a sense that the amount of tribofilm removed at different stages of tribofilm build-up can be seen. We also have shown the effect of physical parameters such as temperature and load on the film removal. This is so important for understanding the new mechanism involved in wear protection” – Ali Ghanbarzadeh, one of the leading researchers commented.
The results of the research shine light on the wear mechanisms of the ZDDP tribofilm and will be very useful in the further development of environmentally friendly anti-wear additives.
Further details can be found in the original research article: http://dx.doi.org/10.1016/j.apsusc.2017.01.178, Parsaeian, P, Ghanbarzadeh, A, Van Eijk, MCP et al. (3 more authors) (2017) A New Insight into the Interfacial Mechanisms Involved in the Formation of Tribofilm by Zinc Dialkyl Dithiophosphate. Applied Surface Science, 403. pp. 472-486. ISSN 0169-4332 .