Round 1

Reviewer 1 Report

This is the comments on the paper N Coatings (ISSN 2079-6412) Manuscript ID

coatings-2004962.Type. Article.

Title: Preparation and properties of plasma-sprayed Fe-Cr-B-C coating.

Authors: Jing Lu , Jiayi He , Dong Chen , Chengchuan Sun , Yimin Li , Fenghua Luo .

Section Plasma Coatings, Surfaces & Interfaces.

This manuscript has been quickly  reviewed by reviewer and the comments are attached at the bottom.

Rate the Manuscript:

1. Significance to field and specialization of  “Coatings (ISSN 2079-6412)”  journal:  good.
2. In the article has been consider the
   Fe-Cr-B-C wear-resistant coating was prepared by plasma spraying technology. The effects of spraying current, main gas flow, auxiliary gas flow and spraying distance on the hardness and bonding strength of the coating were studied. The results show that the microhardness of the coating is relatively uniform, within the range of 820~860 HV0.1. The cross section of the coating is typical lamellar structure. There are unmelted particles with high hardness in Fe-Cr-B-C coating, and the hard phase particles are spherical and dispersed. Spraying process parameters significantly affect the bonding strength of the coating, but have little effect on the microhardness. The coating substrate is α-Fe phase and hard phase are mainly (Fe,Cr)2(B,C) phase and (Fe,Cr)3(B,C) phase, and there is little oxidation during spraying. The wear track depth of Fe-Cr-B-C coating is shallow, with good wear resistance. The wear mechanism of Fe-Cr-B-C coating is mainly abrasive wear and fatigue wear. The fine spheroidized coating structure is helpful to improve the wear resistance.
3. Originality: good.
4. Clarity and presentation:  acceptable.
5. Appropriateness for Journal: appropriate subject mater for the journal “Coatings”.
6. Need for rapid publication: yes.
7. Recommendations: to sent after minor revision to “Coatings (ISSN 2079-6412)”.

However, the following remarks and questions were arisen after reading of the manuscript:

1. Abstract should include only main statements and conclusions of study. Please (if it possible) re-write this section in more compact and clear view.
2. Section “CONCLUSIONS”: Text should be improved.
3. All abbreviations should be explaine.
4. The literature review is weak with limited references, which have experimental results. May be consider the next papers: Laser treatment of plasma coatings.Soviet Materials Science. - New York: Plenum Publishing Corporation.- 1991, vol.27, No 1.- P.51-55. https://doi.org/10.1007/BF00724136

5.Final conclusion. All components of the manuscript should be carefully checked: text, figures and tables. Revised version of paper should be prepared and submitted again.27.10.2022.

Comments for author File: Comments.doc

Author Response

Comments from the editors and reviewers: Reviews 1 1. Abstract should include only main statements and conclusions of study. Please (if it possible) re-write this section in more compact and clear view. Reply: According to your valuable comments, we have carefully rewritten the abstract and conclusion of the article. ABSTRACT: Fe-Cr-B-C wear-resistant coating was prepared by atmosphere plasma spraying. The effects of spraying current, main gas flow, secondary gas flow, and spraying distance on the microstructure, hardness, and bonding strength of the coating were studied. The results show that the cross section of the coating is a typical lamellar structure. There are unmelted particles with high hardness in Fe-Cr-B-C coating, and the hard phase particles are spherical and dispersed. As a result, the microhardness of the Fe-Cr-B-C coating is relatively uniform, within the range of 820~860 HV0.1. Spraying process parameters significantly affect the bonding strength of the coating, but have little effect on the microhardness. The matrix of the coating is α-Fe phase and the hard phase are mainly (Fe,Cr)2(B,C) phase and (Fe,Cr)3(B,C) phase. Due to the spheroidized coating structure, the wear rate of the FeCrBC coating is only 0.62×10-5 mm3/Nm, which is 51 % of that of 304 stainless steel. The wear mechanism of Fe-Cr-B-C coating is mainly abrasive wear and fatigue wear. 2. Section “CONCLUSIONS”: Text should be improved. Reply: According to your valuable comments, we have carefully rewritten the conclusion of the article. Conclusion (1) The microstructure of plasma sprayed Fe-Cr-B-C coating contains a typical lamellar structure with pores and microcracks. The hard phase particles in Fe-Cr-B-C coating are spherical and dispersed. Consequently, the microhardness of that coating is uniform and is in the range of 820-860 HV0.1. (2) The plasma spraying parameters have a significant effect on the bonding strength of Fe-Cr-B-C coating, but have little effect on the microhardness. The optimized spraying parameters are as follows: spray current of 500 A, the main gas flow of 40 L/min, the secondary gas flow of 17 L/min, and spraying distance of 100 mm. The bonding strength and microhardness of the Fe-Cr-B-C coating after process optimization are 69.8 MPa and 852.1 HV0.1, respectively. (3) The Fe-Cr-B-C powder is composed of α-Fe phase, (Fe,Cr)2(B,C) phase (Fe,Cr)23(B,C)6, and a small amount of (Fe,Cr)3O4. The hard phases of Fe-Cr-B-C coating are mainly (Fe,Cr)2(B,C) and (Fe,Cr)3(B,C) phases. (4) Due to the fine spheroidized structure, the wear rate of Fe-Cr-B-C coating is only 0.62×10-5 mm3/Nm, which is 51 % of that of stainless steel. The wear mechanism of Fe-Cr-B-C coating includes mainly abrasive wear and fatigue wear. 3. All abbreviations should be explained. Reply: In the revised manuscript, we carefully revised the Abbreviations. We are sorry for this negligence. For Example: Scanning electron microscopy (SEM, JSM-6390LA, JEOL) 4. The literature review is weak with limited references, which have experimental results. May be consider the next papers: Laser treatment of plasma coatings. Soviet Materials Science. - New York: Plenum Publishing Corporation.-1991, vol.27, No 1.- P.51-55. https://doi.org/10.1007/BF00724136 Reply: We have carefully read and studied this document (Balits’kii, O. I., Pokhmurs’kii, V. I., & Tikhan, M. O. (1991). Laser treatment of plasma coatings. Soviet Materials Science, 27(1), 51–55. doi:10.1007/bf00724136).We have checked and modified the reference. Thank you for your valuable advise. Refers this great paper as: Particles are converted to a molten or highly plastic state in plasma coatings, which are widely used for these reasons, but there are substantial disadvantages in such coatings because of the high porosity and poor adhesion to the substrate[15]. 5. Final conclusion. All components of the manuscript should be carefully checked: text, figures and tables. Revised version of paper should be prepared and submitted again.27.10.2022. Reply: We have carefully checked and modified the orthographic and grammatical errors in manuscript.

Reviewer 2 Report

Whole the manuscript should be completely checked by native editor.

All of the references should be write in same style:

For example ref. 3 and 18 don’t have starting and ending page numbers!

In the manuscript, no recent researches 2022 and even 2021 references were used for discussion section! And just one 2021 and one 2022 published papers were cited.

Data in Table. 1 and Fig. 2 should be repeated at least 3 times and will be reported in (Average+_Standard deviation) and then P-Value should be calculated.

The discussion section should be improved and more recent papers should be compared and cited.

Author Response

Comments from the editors and reviewers:

Reviews 2

1. Whole the manuscript should be completely checked by native editor.

Reply：We are sorry for those linguistic mistakes. We have checked and corrected in total manuscript. Thank you for your careful reading of our manuscript.

2. All of the references should be write in same style:

Reply：Thank you very much for your suggestions. We have carefully checked and modified the references of the manuscript

3. For example ref. 3 and 18 don’t have starting and ending page numbers!

Reply：We have carefully checked and modified the references of the manuscript. The reference 3 and 18 (refs. 20 in revised manuscript ) only has the document number, not the page number. We have read the Instructions for Authors carefully, and read some papers download from journal "coating". we think they are in right style.

4. In the manuscript, no recent researches 2022 and even 2021 references were used for discussion section! And just one 2021 and one 2022 published papers were cited.

Reply：We recognize that recent literature is an important data for judging and analyzing the value of this research, and we supplement and cite relevant literature. The above changes have been added to the results and discussion section of revised draft. We refers some new papers as:

[19] Zhang, J.D.; Huang, W.Z.; Hu, T.T.; Zeng, N.; Fan, X.Z. Effect of Critical Plasma Spray Parameters on Microstructure and Mechanical Properties of Plasma-Sprayed YSZ-20 wt%LSM Composite Coating.      J. Therm. Spray Technol. 2022, 31(3), 436-448.

[20] Shi, M.; Xue, Z.; Zhang, Z. Effect of spraying powder characteristics on mechanical and thermal shock properties of plasma-sprayed YSZ thermal barrier coating. Surface and Coatings Technology. 2020, 395, 125913.

[21] Kumar, S.; Kumar, R. Influence of processing conditions on the properties of thermal sprayed coating: a review. Surf. Eng. 2021, 37(11), 1339-1372.

[22] Hong, J.; Qian, Y.; Zhang, L.; Huang, H.; Jiang, M, Yan, J. Laser nitriding of Zr-based metallic glass: An investigation by orthogonal experiments. Surf. Coat. Tech. 2021, 424, 127657

.

5. Data in Table. 1 and Fig. 2 should be repeated at least 3 times and will be reported in (Average+_Standard deviation) and then P-Value should be calculated.

Reply：Thank you very much for your suggestion. Three parallel samples were set for the bonding strength test. The bonding strength of the coating in this paper is the average value of the three groups of samples. Considering the high dispersion of hardness of the coating, we measured 10 points and average them. These data error bars were added in the revised draft, as shown in the figure below.

6. The discussion section should be improved and more recent papers should be compared and cited.

Reply：We have added relevant literature and modified the discussion in the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript is on topic in the field of preparation of plasma-sprayed Fe-Cr-B-C coating and evaluation of the properties of these coatings. The research results are interesting and the manuscript is recommended for publication. However, a few points should be clarified before publishing.

1. Lines 126, 127, Table 1. There are problems with the calculation of parameters K1, K2, K3 and D1, D2. The text of the manuscript refers to a paper [19] in the journal China Surface Engineering, but this paper is difficult to access.

2. Line 170, Table 2. This table is missing from the manuscript.

Author Response

Comments from the editors and reviewers:

Reviews 3

1. Lines 126, 127, Table 1. There are problems with the calculation of parameters K1, K2, K3 and D1, D2. The text of the manuscript refers to a paper [19] in the journal China Surface Engineering, but this paper is difficult to access.

Reply：In the revised manuscript, we revised the reference. We are sorry for this negligence. We refers the following paper, which have a describe on orthogonal experiments:

[22] Hong, J.; Qian, Y.; Zhang, L.; Huang, H.; Jiang, M, Yan, J. Laser nitriding of Zr-based metallic glass: An investigation by orthogonal experiments. Surf. Coat. Tech. 2021, 424, 127657

.

2. Line 170, Table 2. This table is missing from the manuscript.

Reply：We are sorry for our careless and we have corrected it in the new manuscript. Thank you for your careful reading of our manuscript.

Table 2 Result of friction and wear test of Fe-Cr-B-C coating and substrate

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

It is accepted in this revised version.