Tribological Behavior and Self-Healing Properties of Ni3Al Matrix Self-Lubricating Composites Containing Sn-Ag-Cu and Ti3SiC2 from 20 to 800 °C
Round 1
Reviewer 1 Report
The work still needs to be refined. I suggest a mandatory review of the following points to increase the quality of the paper.
1. Provide complete details of the powders used, i.e., manufacturer, and country.
2. The same applies to any test apparatus used, e.g. tribometer, 3D printer, SEM, XRD, EDS, and Raman spectroscope. There is no information for some devices. Name, manufacturer, and country of production should be provided.
3. Reporting relative humidity for tests at 200, 400, 600 and 800C is incorrect. Humidity probably concerned the room and not the test system, a friction pair in a closed chamber.
4. EDS analysis is not suitable to determine the carbon content. Remove its contents from the EDS spectra.
5. The authors insert references to the literature into the text. In my opinion, there is a lack of discussion and references to the results of other works. For example, the authors wrote "The main wear mechanism of NST is abrasive wear [24]. As presented in Figure 7(b), obvious spalling and oxides indicate that the main wear mechanisms of NST at 800 ° C are adhesive wear and oxidative wear [ 21]." This is not a discussion. I even wonder if these references make sense. After all, you describe your observations on the basis of your knowledge, which you probably also took from these items from the literature. Of course, there are places at work where references fit perfectly, e.g., „... on the worn surface, which have good antifriction effects [28]. In addition, TiC and TiO2 with high hardness can reinforce the lubricating film of NST [ 29, 30], improving the wear resistance of NST at high temperature".
Recommendation: This manuscript in the presented form is not acceptable for publication in Coatings. A major revision is necessary.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
1. At least one line of application is required in Abatract. Further, line 13-16 is not very clear. rewrite for better clarity. Moreover, describe the methods of fabrication of MMC in the abstract and the abstract should be more quantitative in terms of improvements.
2. Research gap and objective should be more clear. rewrite it.
3. Preparation method of as-prepared samples is missing. include it. Further, the reason has to mention the selection of the Si3N4 ball and include the load, and indentation time for evaluating microhardness.
5. The author should mention the scientific reason for the presence of the Ti3SiC2 phase.
6. The author should add at least one raw data of friction and include how to calculate the wear rate.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The paper is about the mechanisms of self-lubrication during friction of the developed composite coatings in a wide temperature range. This is relevant for friction units operating completely or partially without lubrication. The main conclusions are drawn from the results of studying surfaces after friction by microscopy, chemical analysis, and Raman methods. The high scientific level and novelty of this part of the paper are beyond doubt. However, there are shortcomings (lack of information) in terms of tribology. My comments are below.
1. There is no description of the friction process. Is there a running-in process and a steady state? How does the duration of the running-in process depend on temperature? Is the average value of the coefficient of friction over the entire test period or is it typical for the steady state? The processes that occur during running-in can also become an object of analysis, since it is often important to reduce the running-in time.
2. What happens to the counter-body (ball)? How worn out is it? In the process of ball wear, a sharp decrease in the maximum contact pressure occurs, on which, as well as on temperature, the mechanisms of friction and wear depend.
3. Was the surface of the ball been examined? Is there a transfer of the lubricating film to the ball?
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
Authors investigates Tribological behavior and self-healing properties of Ni3Al matrix self-lubricating composites containing Sn-Ag-Cu and Ti3SiC2 from 20 to 800 °C. The idea of the paper is interesting and it has well organized. However, it needs modifications before recommendation for publication. Here are my comments that I encourage authors to revise their paper carefully according with them.
1) The wear testing configuration is constant. What will be the composite behavior in other conditions of tribology test?
2) Kindly strengthen the introduction by explaining more about the application of such composites.
3) Add a photograph of the sample before and after specimens?
4) What is your reason for choosing these percentages for additive? It is obvious author can try other additive ratios.
5) The selection of those kind of additives used in the present work should be justified specially in introduction section.
6) Authors could check both width and depth of tribology path by profilometer instrument and report the results.
7) Does the tribofilm act as a transfer film? How does it work?
8) How did you prepare the samples for the SEM analysis? Please add the information.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have taken into account the comments of the reviewer and made corrections in this article. They have responded to all the comments from the reviewer.
Recommendation: This manuscript in the presented form is acceptable for publication in Coatings.
Reviewer 2 Report
No Comments
Reviewer 3 Report
All comments regarding the first version of the paper are taken into account in the revision. The paper is recommended for acceptance.
Reviewer 4 Report
Accepted
