Nanoscale Mechanical Properties of In-Situ Tribofilms Generated from ZDDP and F-ZDDP with and without Antioxidants

Abstract

Tribofilms with thickness ranging from 100-200 nm were developed in-situ during wear tests using a zinc dialkyl dithiophosphates (ZDDP) and fluorinated ZDDP (F-ZDDP). The influence of the antioxidant alkylated diphenyl amine on the formation and properties of these tribofilm is examined. Results indicate that the thickness of the tribofilms formed when F-ZDDP is used is always thicker than the tribofilm formed with ZDDP. In addition, in the presence of antioxidants the tribofilm thickness is increased. The hardness of these tribofilms in the absence of the antioxidants is significantly higher at the near surface region (0-30 nm) when compared to the films formed in the presence of antioxidant. Nanoscratch tests conducted to examine the abrasion resistance of the tribofilms also indicate that the tribofilms formed by F-ZDDP are more resistant to scratch compared to films formed by ZDDP. In the presence of antioxidant, tribofilms formed by F-ZDDP are significantly thicker while both films behave in a similar fashion in nanoscratch tests. Transmission electron microscopy of the wear debris formed during the tests were examined and results indicate the nucleation and growth of nanoparticles of Fe3O4 with an approximate size of 5-10 nm embedded within an otherwise amorphous tribofilm.

Fluorinated interactions in two different plain ZDDP oils using design of experiment (DOE) and chemistry characterization of tribofilms

“…Both images indicates stable and smooth tribofilms are formed with thicknesses range 300-400 nm. This thickness of tribofilms measured is consistent with several studies (Somayaji et al, 2007;Kim et al, 2010;Platinum Research Corporation, 2000). The tribofilm formed with F-plain ZDDP oil 1 is approximately 400 nm thick while the tribofilm from F-plain ZDDP oil 2 is approximately 380 nm thick.…”

“…The reduced elastic modulus was calculated using the Oliver and Pharr (1992) method and hardness was calculated by getting the ratio of applied load to the projected area of indentation. The calculation method is similar to the one established by Somayaji et al (2007) and Nehme et al (2010). Figure 12 shows All things considered, both oil formulations established good tribofilms in the bulk which are more compliant and correlate closely with related studies (Pereira et al, 2010;Kim et al, 2010;Somayaji et al, 2007).…”

“…The calculation method is similar to the one established by Somayaji et al (2007) and Nehme et al (2010). Figure 12 shows All things considered, both oil formulations established good tribofilms in the bulk which are more compliant and correlate closely with related studies (Pereira et al, 2010;Kim et al, 2010;Somayaji et al, 2007). On the other hand in the case of F-plain oil 1, all SEM, EDS, X-ray, tribosurfaces (Figure 6), and areas of tribofilm images present better antiwear resistance and the lower hardness and reduced modulus support that indication.…”

Analysis of fluorinated interactions in plain ZDDP and fully formulated oils using design of experiment (DOE) and chemistry characterization of tribofilms in boundary lubrication under extreme loading conditions

“…Both images indicates stable and smooth tribofilms are formed with thicknesses in the range of 300-400 nm. This measured thickness of tribofilms is consistent with several studies (Somayaji et al, 2007;Kim et al, 2010;PRO, 2000). The tribofilm formed with F-plain oil 1 is approximately 400 nm thick while the tribofilm from F-fully formulated oil 1 is approximately 300 nm thick.…”

“…On the contrary, it shows an increase in F-fully formulated oil 1 tribofilm. All things considered, both oil formulations established good tribofilms in the bulk which are more compliant and correlate closely with related studies (Somayaji et al, 2007;Pereira et al, 2010;Kim et al, 2010). On the other hand in the case of F-plain oil 1, all SEM, EDS and X-ray analysis, tribosurfaces ( Figure 7) and areas of tribofilm images present better anti-wear resistance and lower hardness and reduced modulus support that indication.…”