Improved Loss-of-Lubrication Performance with Lubricants Containing Nano-Graphene Platelets and Ionic Liquids
Round 1
Reviewer 1 Report
This is an experimental study on the viability of two lubricant additives, nano-graphene platelets and a phosphonium-phosphate based ionic liquid, in rotorcraft gearbox oil for improving the scuffing resistance of gear steels under starved loss of lubricated conditions. The work seems to be done very carefully and consistently and the paper is well written. The paper should be published in "friction" after some minor revisions as follows:
1. The authors had better show the experimental setup graphicly.
2. Line 104 to 107: "Nano-graphene (NG) platelets of dimension 1 to 5 nm were selected. In this set of lubricant blends, IL concentration was varied from 1 wt% to 5 wt% while keeping the NG concentration fixed at 0.02 wt%, which is 4 to 5 times less concentration than in similar studies of graphene added to oil [21,22]." Why did the author choose 0.02 wt% instead of the one close to similar studies so that comparison can be made?
3. Figure 2: point A and B are NOT shown in Figure 2.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Two issues are of concern. 1. As noted in the work, with an increase in the scuffing load, each component of the additive separately exceeded the base oil, but both additives together showed a negative effect. The reason for this is still unclear. It may be necessary to study the ratio of components more carefully or even replace the phosphorus-containing part of the composition. 2. When formulating modern compositions of additives to lubrication, developers strive to avoid the use of phosphorus in the composition of additives. The current concept is Low SAPS (low sulphur, ash and phosphorus) corresponds to this trend.
There is a small remark. On page 4, it says that in Fig. 2 there are symbols – points A and B, but these points are not shown in the figure.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
In the paper “Improved Loss-of-Lubrication Performance with Lubricants Containing Nano-graphene Platelets and Ionic Liquids” the resistance to scuffing under starved lubrication of mixtures of base oil, nanographene platelets and a phosphonium-phosphate ionic liquid has been studied.
Authors have developed a very interesting work by studying the performance of the new lubricants under loss of lubrication conditions, in order to solve a real problem. The results obtained shows the synergistic effect of the two additives when the loss of lubrication is evaluated. However, this synergistic effect is not observed in the scuffing load test.
However, the manuscript contains several aspects that must be improved in order to take into account this work for publication.
- Which is the procedure to obtain the new lubricants? Time of ultrasonication, sequence of mixture etc. should appear in the text.
- Thermal analysis of the new lubricants must be done, in order to confirm that there is not degradation of the lubricants with temperature.
- How many tests have be made to obtain the results?
- In Lines 183-184 and 210-211 there are reference of points A and B in Figure 2, but those point are not in the Figure
- In the part of results, I would recommend explaining the ball- on -disking results all together, and before or after explaining the pin-on –flat results. It is a bit difficult to be sure of what kind of experiment are you explaining
- Figure 7, the images are not on the right or on the left.
- I would propone to made surface analysis in order to confirm the nature of tribofilms.
- Bibliography must be update. Only 5 references are from the last 5 years.
- References must have the same format.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Authors of “Improved Loss-of-Lubrication Performance with Lubricants Containing Nano-graphene Platelets and Ionic Liquids” have considered the suggestions provided and they have also answered kindly to the comments and doubts.
In my opinion, the manuscript can be published after a minor revision of the references. I have observed that authors have changed the style of the references, however, some of them, as nº 4, 10, 12 or 20 must be reviewed.
Author Response
We have checked all the references again. The format is consistent with the MLA format as confirmed by google scholar. No problems were noticed with references 4,10,12 and 20. However, we did notice and correct an error with reference 19.
Please see attached manuscript. Thank you.
Author Response File: Author Response.pdf
