Towards optimum additive performance: A numerical study to understand the influence of roughness parameters on the zinc dialkyldithiophosphates tribofilm growth

In recent years, several theoretical models to predict the triboreactive film thickness of zinc dialkyldithiophosphates (ZDDP) have been developed. Although these models are not complete and are approximate in nature, they provide a framework which can be used to evaluate the factors impacting the tribofilm growth. In this paper, rough surfaces with different roughness parameters were numerically generated and used to calculate the tribofilm growth. The simulation results show that lower negative skewness, higher kurtosis, and larger autocorrelation length values give thicker ZDDP tribofilms with skewness and autocorrelation values having a greater effect on the tribofilm growth. Based on the simulation results, it is found that these parameters influence the tribofilm growth by changing the contact ratio which eventually changes the dynamic growth of tribofilm and wear of substrate. The results presented in this paper have bigger implications for industry in designing surface textures that promote the anti-wear action.