Microstructural Properties and Wear Resistance of Fe-Cr-Co-Ni-Mo-Based High Entropy Alloy Coatings Deposited with Different Coating Techniques

Round 1

Reviewer 1 Report

The paper is well-written and presents a comparison of three deposition processes regarding surface morphology and microstructure. A broad characterization was executed, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and tribological properties with hardness and wear sliding tests.

However, the methodology was not consistent. First, it lacks a Design of Experiment (DOE). Second, just one parameter for each deposition process is not sufficient to conclude if this process is better than the other in terms of roughness and friction coefficient. If other parameters were selected, the conclusion could be different.

Based on that, the publication is not recommended in the present form. The following methodological approach is suggested:

1 – Develop a DOE matrix for each process – fix powder composition and size – vary power and speed for example

2 – Analyze the results – surface morphology (roughness) and friction coefficient for each process and parameter variation through a graphic map

3 – Compare the graphic maps

Author Response

The authors appreciate the time and effort from the reviewer for reviewing the manuscript and the comments. A design optimisation phase was performed as part of a research project called Geo-Coat, which this study was part of. The coatings analysed in this study were the result of this optimisation for each process, i.e. the coatings for this study were produced based on the results from the optimization process of the different coating processes. The optimisation performed involved a variation in process parameters, e.g. evaluation on % of dilution was done (for laser cladding), spray distance and angles (for HVOF), and adhesion and microstructural defects (the less the better) (for ESD) for the optimisation, but presenting this work was not the scope of this paper and thus not presented as part of this work. Explanation of this has been added on page 4 in the revised manuscript in the section 2.1 Materials and Coating Processes.   

Reviewer 2 Report

See my Comments and Suggestions for Authors in the attached PDF.

Comments for author File: Comments.pdf

Author Response

Thank you for your time and effort in reviewing the manuscript and your valuable comments. The manuscript has been revised according to your comments as highlighted with yellow and track changes in the revised manuscript as summarized here below for each comment: 

Reviewer comments: The present structure of the manuscript is (NOTE: there are three minor “discrepancies”):

2.4. Tribological: friction and wear testing testing. This has been deleted in the manuscript according to this comment.

3.1.3. Morphology and microstructural characterization of the LC HEACs. This has been revised according to this comment.

5. Conclusions (Note: should be 4.) This has been fixed in the manuscript.

General comments: This is a very long manuscript (with a total of 30 pages; 12 figures and 8 tables) presenting in detail the microstructural, mechanical and tribological properties of High Entropy Alloy Coatings (Co19Cr17Fe19Ni18Mo27 and Co20Cr20Fe20Ni20Mo20) deposited by 3 different techniques: high-velocity oxygen fuel 20 (HVOF), laser cladding (LC), and electro-spark deposition (ESD). Proposed wear mechanisms are discussed. It is said that “This work was part of the H2020 EU Geo-Coat project”. Due to the relevancy of the topic and the envisaged applications, this manuscript is recommended for publication, but some improvements are suggested:

1) In my opinion, at the end of such long manuscript, the CONCLUSIONS (presently written in a single and monotonous paragraph) could be presented (to the readers …) in a much more attractive way. The conclusions have been revised according to the reviewers’ comment.

2) At the Abstract: Avoid the direct use of the abbreviation HEACs without explaining the meaning. Most readers are more familiar with the abbreviation. This has been fixed in the abstract.

 

 

 

Reviewer 3 Report

• In abstract should be add to beginning some general introduction about manuscript topic.
• In abstract is way too much conclusion information, it has to be shortened.
• Between number and unit should be gap. For example here: "-56+20μm, -35+10μm and -161 150+63μm".
• All figures are good readable and very nice and clear. Only Fig. 8 should have bigger font of text for legend on scales.
• I recommend to rewrite Conclusion as a list of results.
• Manuscript has nice and adequate discussion.

Author Response

The authors thank the reviewer for the time and effort in reviewing the manuscript and the valuable comments. The manuscript has been revised according to the comments as stated here below and highlighted with yellow in the revised manuscript.

Comments and Suggestions for Authors

1. In abstract should be add to beginning some general introduction about manuscript topic. This has been revised, general introduction has been added to the abstract.
2. In abstract is way too much conclusion information, it has to be shortened. The abstract has been revised according to this comment.
3. Between number and unit should be gap. For example here: "-56+20μm, -35+10μm and -161 150+63μm". This has been revised according to this comment.
4. All figures are good readable and very nice and clear. Only Fig. 8 should have bigger font of text for legend on scales. This has been revised according to this comment.
5. I recommend to rewrite Conclusion as a list of results. The conclusions have been revised according to the reviewers’ comment.
6. Manuscript has nice and adequate discussion.

Round 2

Reviewer 1 Report

The authors did not follow the suggestions from the first review. Therefore, publication is not recommended.