Wear Features of Nickel-Based Superalloy ZhS6U and Commercial Pure Titanium During Dry Friction in a Pin-on-Disc Scheme

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors

The study is well-structured and generally clear; however, some revisions are required before the manuscript can be considered for publication.

Abstract: Add key quantitative findings in the abstract.

Introduction: Clearly state the research gap and how this study advances the understanding of frictional behavior between ZhS6U and titanium.

Materials and Methods: Include statistical analysis or at least repeatability data (e.g., standard deviation or confidence intervals) for wear rate and friction coefficient.

Results and Discussion: Provide a deeper quantitative comparison with previous studies (Refs. [7–12]) on Ni-based alloys and similar temperature/friction conditions. Expand on the interpretation of the tribolayer formation mechanism, connecting oxidation and mechanical mixing with diffusion processes in both materials. Discuss in more depth the relationship between tribological behavior and potential friction stir welding conditions (temperature, pressure, velocity).

Conclusions: Rewrite the conclusions as bullet points summarizing major findings, wear mechanisms identified, and implications for industrial processes.

References: Consider including more comparative studies from other research groups to broaden the scientific basis.

General Comments: Ensure consistency in notation: italicize variables, use SI units, and format tables and figure captions.

Comments on the Quality of English Language

The manuscript is generally well written but would benefit from minor English polishing for conciseness and flow.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript titled “Wear Features of Nickel-Based Superalloy ZhS6U and Commercial Pure Titanium During Dry Friction in a Pin-On-Disc Scheme” investigates the comparative wear behavior of a nickel-based superalloy and pure titanium under dry friction conditions. The topic is relevant to tribology and surface engineering, and the work aligns with the scope of Eng (MDPI). The study adds value to the fields of tribology and surface engineering by providing comparative experimental insights into the dry friction behavior of nickel-based and titanium materials. 
However, the manuscript also has some limitations and weaknesses that need to be addressed and improved. Here are some specific recommendations and suggestions for each section of the manuscript:
Introduction
1.    The introduction gives a general overview of tribological challenges in high-temperature alloys but lacks depth in connecting previous findings to the present study. Several key studies on dry sliding wear of nickel-based superalloys and titanium alloys (particularly in pin-on-disc configurations) could be added to strengthen the context. The discussion of friction mechanisms could also cite more recent works from the last 3–5 years.

2.    While the introduction highlights the industrial need for wear-resistant materials, the specific knowledge gap is not explicitly defined. The authors should clearly state what has not yet been investigated to strengthen the study’s justification.

3.    The aims and objectives are presented in a vague and general manner. It is recommended to include a concise, clearly separated “Aims” paragraph at the end of the introduction, outlining the main research goals and scientific contributions of this work.

Materials and Methods

4.    The rationale behind the chosen parameters (load, speed, time) is not clearly linked to prior studies or preliminary trials. The authors should explain whether these conditions were selected based on standard ASTM procedures, literature precedent, or optimization trials.
5.    Did the authors measure the surface roughness of both friction bodies before conducting the wear tests? If so, please provide the corresponding roughness values in the Materials and Methods section. Surface roughness is a critical parameter influencing friction and wear behavior, and reporting these values is essential for ensuring reproducibility and accurate comparison of results.
Results
6.    Figure 7 presents wear track images labeled (a–d), but the figure caption does not describe what each subfigure specifically represents. Please revise the caption to provide full descriptions of all subfigures and briefly indicate the observed wear features or trends. Clear figure labeling and detailed captions are necessary for proper interpretation and reproducibility of results.

The manuscript needs major revision before it can be considered for publication. The authors need to address all the recommendations and suggestions mentioned above to improve their manuscript.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The paper leaves a positive impression. Its novelty lies in the analysis of friction and wear of a previously unexplored friction pair at high temperatures. The effect of speed on the friction coefficient and wear is analyzed. The reviewer believes the mechanisms of frictional interaction are explained correctly. The paper may be published after corrections according to the comments below.

1. The relevance of studying this particular friction pair should be emphasized at the end of the introduction.
2. A motivation for the choice of friction parameters (load, temperature, etc.) is required.
3. The pin diameter is specified. Does this refer to the cylindrical part or the rounded tip?
4. At what accelerating voltage were the SEM images obtained and the EDS analysis performed?
5. It is better to relate wear intensity to distance rather than time. Otherwise, the results obtained at different speeds appear trivial.
6. In Figures 8c and 11b, the text is difficult to read due to the chosen color.

Comments on the Quality of English Language

It appears the authors used automated translation. There are no grammatical errors, but some phrases are misleading. Their meaning is only clear from the context.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I recommend that the manuscript be accepted in its present form.

Reviewer 3 Report

Comments and Suggestions for Authors

The revised version can be published

Comments on the Quality of English Language

It appears the authors used automated translation. There are no grammatical errors, but some phrases are misleading. Their meaning is only clear from the context.