Investigation of the Lubrication Performance of γ-Al2O3/ZnO Hybrid Nanofluids for Titanium Alloy
Round 1
Reviewer 1 Report
I read the article and I think it can be improved. Some disadvantages are listed below:
What kind of control group is that, which lubricant? Listed under number 8 in Figure 5.
Pure Al2O3 has correct properties in terms of wear and a low coefficient of friction. I don't see the importance of hybrid lubricants in relation to Al2O3?
Have you performed repeatability experiments? How reliable are the measurement results?
When you talk about surface morphology, were you able to measure the roughness of the machined surface?
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Suggestions for improving the manuscript are as follows:
1. I don't think a group citation is necessary in the first paragraph of the Introduction section.
2. The authors wrote the objectives of this research in the Introduction section. However, a scientific contribution should be highlighted at the end of this section. It is also necessary to write scientific hypotheses.
3. Figure 1 shows the tribometer scheme. Can a photo of the tribometer be shown in addition to the scheme?
4. What is the accuracy of the measurement instrumentation?
5. Currently, the universality of the applied methodology is hidden. It should highlight what is new in theory and/or experimental techniques.
6. Is it possible to explain the following sentence or cite a reference: "Cemented carbide is the optimal tool material for machining Ti 6Al 4V titanium alloy".
7. It is not clear how the friction coefficient curves were obtained.
8. Cost analysis would significantly improve the quality of research.
9. Is it possible to assess the negative environmental impact of hybrid and pure nanofluid?
10. All results should be further scientifically discussed and, if possible, compared with the results of previous researches.
11. Currently, only the main results of the research are repeated in the conclusions. The conclusions should be significantly corrected. The scientific contribution of the research should be highlighted. What are the benefits of research? What are the possibilities of practical application? What are the limitations of the research? What are the directions of future research?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
This manuscript investigates the lubricating performance of γ‑Al2O3/ZnO hybrid nanofluids for Ti‑6Al‑4V. The pure and hybrid nanofluid are compared, and the effects of γ‑Al2O3/ZnO ratios are studied. The results show that γ‑Al2O3/ZnO hybrid nanofluids outperform pure nanofluid in terms of lower friction co‑efficients and better surface quality. Moreover, the hybrid nanofluid with a mass ratio of Al2O3 to ZnO of 2:1 demonstrates the best lubrication performance with a reduced friction coefficient of up to 22.1% compared to the base solution, resulting in improved surface quality. Al2O3 nanoparticles can adhere to the surface of ZnO nanoparticles and work as a coating, which further enhances the lubrication performance of the water‑based nanofluid. The authors designed the work systematic way by performing some valuable experimental works. It is also necessary to critically evaluate new data and not make hasty conclusions that may lead to misinterpretations. However, several points are important to be addressed before going to possible publication in this high-quality journal.
1. Conclusion also needs to be rewritten. Include the following: new concepts and innovations demonstrated in this study, a summary of findings, a comparison with findings by other workers, and a concluding remark.
2. Details of test rig components - measuring ranges and accuracy of the measuring devices are not stated.
3. Please provide the statistical test results, e.g. Fig.5 (standard deviation). Please indicate how many rounds of trials were conducted? Please also report their variances.
4. Authors cite 30 source, however only 6 of them were published in last 5 years. It is less than 20% of all the list of references. Authors should analyse up-to-date publications.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors accepted the suggestions and improved the article.
Reviewer 2 Report
The authors responded adequately to all my comments and I do not have more essential remarks. I recommend a reviewed article for the publication.
