Defect Formation Mechanism and Performance Study of Laser Cladding Ni/Mo Composite Coating

Round 1

Reviewer 1 Report

Mass loss, wear rate, wear resistance, specific wear rate, and co-efficient of friction with the respective cladding and base materials should be clearly represented with clear table formulations and along with suitable mathematical expressions that you can achieve the improvements.

Figures 5 and 6 should include the y bar error and repeat the sample at least three times to improve accuracy and provide sample evidence to support the actual record.

Figures 3 and 4 should properly mention and explain each phase indicated in the figure, as well as provide appropriate literature support for previous work.

Figure 1 should show the exact lattice parameter and phases, as well as the grain size of each phase and volume fraction, as shown in the XRD diagram.

It should optimise the process parameters and clearly show how you can accomplish the task of improving laser cladding.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

In abstract, Add the information about the Defect formation mechanism and performance. No such observation found.

Add more literature and compare the findings of research related to cladding to minimize the defects and to improve the performance.

Writ the standard procedure to prepare cross-section for hardness measurement.

Index the XRD patterns according to JCPDS data. Compare the finding with the literature.

From the Fig. 2, No visible pores and cracks Can be observed in the mixing area of Mo and Ni layer area. However, in Fig. 3, authors are reported pores and cracks on the surface of the Mo layer.

What is the main reason to improve the hardness and wear resistance. Add proof of indentation marks on coating. 

Index the Wear morphology in Fig. 8.

Re-write the conclusion part and add the significant findings.

Author Response

List of Responses

Dear Editors and Reviewer:

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled "Defect formation mechanism and performance study of Laser Cladding Ni/Mo composite coating " (Manuscript Number: coatings-145145). Those comments are all valuable and very helpful for revising and improving our paper, as well as the essential guiding significance to our researches. We have studied comments carefully and have made a correction, which we hope to meet with approval. The revised portion is marked in red in the paper. The leading corrections in the paper and the response to the reviewer’s comments are as flowing:

Reviewer2

1.”In abstract, Add the information about the Defect formation mechanism and performance. No such observation found.”

Thanks for your suggestions! the information about the Defect formation mechanism and performance was added. "Due to the fluidity and non-equilibrium solidification of Mo in the molten state, pores and cracks along the grain boundary were observed in the Mo layer.."(Page1 line 12)

2.”Add more literature and compare the findings of research related to cladding to minimize the defects and to improve the performance.”

Thanks for your suggestions! Related literature[29,30] has been cited in3.6. The main contents are as follows:(Page11)

The addition of CeO₂ is equivalent to adding many non-spontaneous crystal nuclei in the molten pool, increasing the nucleation rate and crystal grain size. CeO₂ can increase the absorption rate of laser radiation energy, so that more substrates are melted into the molten pool, thereby reducing the difference in thermal expansion between the Mo layer and the substrate. Reducing the thermal stress between the cladding layer and the substrate can reduce the tendency of cracking.

3.”Writ the standard procedure to prepare cross-section for hardness measurement.”

Thanks for your suggestions! The cross-section hardness of the cladding layer is averaged by three average measurements, and Schematic diagram of hardness measurement path are as follows:

Figure 2. Schematic diagram of hardness measurement path

4. “Index the XRD patterns according toJCPDS data. Compare the finding with the literature.”
5. “From the Fig. 2, No visible pores and cracks can be observed in the mixing area of Mo and Ni layer area. However, in Fig.3, authors are reported pores and cracks on the surface of the Mo layer.”

Thanks for your suggestions!The cladding layer is divided into three layers, namely Mo layer, Mo-Ni-Cu mixed layer, and Ni-Cu mixed layer. pores and cracks were observed in the Mo-Ni-Cu mixed layer and Mo layer. But most of the pores are observed in the Mo layer.

6.”What is the main reason to improve the hardness and wear resistance. Add proof of indentation marks on coating. ”

 Thanks for your comments and suggestions."Mo layer grains can be refined under the action of laser cladding. It is formed a fine dendritic structure, thereby the hardness of the surface layer is improved. It can be observed from Fig.7 that the hardness of the Mo-Ni-Cu mixed layer is higher than that of the Mo layer, which is attributed that there are hard phase Ni3Mo and fine grain strengthening."which was explained in 3.4(Page9 line 284)

7. ”Index the Wear morphology in Fig. 8.”

Thanks for your suggestions! I have indexed the wear morphology. Fig.9 (a) shows the wear morphology of Cu, a large area of adhesion wear pits appear on the Cu surface, which is mainly adhesive wear[25](Page 11 line 320).The main wear mechanism of the Mo is abrasive wear[27][28].(Page 11 line 331)

8.”Re-write the conclusion part and add the significant findings.”

Thanks for your suggestions! Conclusion has been rewritten.In the conclusion part, the structure, phase, wear mechanism and crack formation mechanism of the laser cladding Mo-Ni composite coating on the copper surface are summarized.

“(1)By using a laser power of 6000W , the scanning speed of 5mm/s and the feed rate was 10 g/min. Three layers of Ni layer and two layers of Mo layer was cladded. Cladding layers with pure Mo on the surface can be prepared.

(2)Due to the compresensive factors such as poor fluidity of the molten pool of Mo and non-equilibrium solidification of the laser, pores and cracks are easily formed in the pure Mo layer.

(3)In order to prepare wear-resistant and high thermal conductivity coating on the Cu, Ni was introduced to overcome the incompatibility of Cu and Mo. The surface hardness of the cladding layer can be increased by 3 times than that of the substrate. The volumetric wear rate of copper is 3 times that of the cladding layer. The main wear mechanism of the Mo is abrasive wear, and the Cu is adhesive wear. ”

Author Response File: Author Response.docx

Reviewer 3 Report

In my opinion, the paper is not yet ready to publication. Major revisions are in order for the authors to address the comments detailed below.
1. As is known, the Introduction should briefly place the study in a broad context and highlight why it is important. The current state of the research field should be reviewed carefully and key publications cited. In the Introduction section, it should be mentioned that not only works of scientists from one country is carried out in the field of laser cladding metal composite coating, but also in other countries. In this case, it is necessary to make references to well-known Refs. 10.1016/j.matdes.2013.08.060, 10.1016/j.addma.2018.05.017, 10.4028/www.scientific.net/KEM.685.403, and 10.1016/j.addma.2018.03.025 for example.
2. To write the Introduction section, it is recommended to briefly mention the main aim of the work and highlight the main conclusions. Keep the introduction comprehensible to scientists working outside the topic of the paper. It would be rational apart from highlighting the main conclusions, briefly mention the main aim of the paper. It is necessary to exclude the phrase “were studied” from the narration, replacing it with “the purpose of this work is”.
3. If the authors would clarify what is the novelty of the work in comparison with previously published Refs., they would have done the introduction comprehensible to scientists working outside the topic of the paper.
4. In the section 3. Results and analysis (maybe “Results and Discussion”), very little information is devoted specifically to the discussion. It might be better to supplement the article with subsection 3.6, which would fill the existing gap. It would be nice to finish this paper with some sort of future perspective on this topic. This would be very valuable for the work done here.
5. Despite the interesting content of the article, the conclusions seem too short and do not reveal details.

Author Response

List of Responses

Dear Editors and Reviewer:

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled "Defect formation mechanism and performance study of Laser Cladding Ni/Mo composite coating " (Manuscript Number: coatings-145145). Those comments are all valuable and very helpful for revising and improving our paper, as well as the essential guiding significance to our researches. We have studied comments carefully and have made a correction, which we hope to meet with approval. The revised portion is marked in red in the paper. The leading corrections in the paper and the response to the reviewer’s comments are as flowing:

Reviewer 3

1. As is known, the Introduction should briefly place the study in a broad context and highlight why it is important. The current state of the research field should be reviewed carefully and key publications cited. In the Introduction section, it should be mentioned that not only works of scientists from one country is carried out in the field of laser cladding metal composite coating, but also in other countries. In this case, it is necessary to make references to well-known Refs. 10.1016/j.matdes.2013.08.060,

10.1016/j.addma.2018.05.017,

10.4028/www.scientific.net/KEM.685.403, and 10.1016/j.addma.2018.03.025 for example.

Thanks for your suggestions! The copper guide rail is the main component of the electromagnetic gun, which is easy to cause abrasion. Mo has the characteristics of high hardness and good heat conduction. Therefore, the wear-resistant coating is prepared on the Cu surface. Since Mo and Cu do not melt, Ni is used as the transition layer. Because copper has good thermal conductivity, laser cladding on the copper surface and ensuring that the copper will not be over-melted has always been difficult.

I have cited the above reference as follows: ”Patrick W. [13]Leech performed laser cladding on the surface of composite high-alloy steel and found that pores and cracks extended from the surface to the bottom of the collective. The cracks can be reduced by controlling the laser power and scanning speed.Florian Wirth et al.[14] established a laser cladding simulation model to predict the height and width of the cladding, so as to achieve the purpose of process optimization.V.G.Smelov et al.[14] designed a laser sintering experimental device. By establishing a fine-powder laser sintering process algorithm, defect-free samples can be obtained, thereby obtaining a sintering zone without pores and cracks. But the Technology for producing a fine powder requires the  use of expensive equipment”. (Page2 line 69-78)

2.To write the Introduction section, it is recommended to briefly mention the main aim of the work and highlight the main conclusions. Keep the introduction comprehensible to scientists working outside the topic of the paper. It would be rational apart from highlighting the main conclusions, briefly mention the main aim of the paper. It is necessary to exclude the phrase “were studied” from the narration, replacing it with “the purpose of this work is”.

Thanks for your suggestions! 

In order to solve the non-wear characteristics of the copper surface, Mo has the characteristics of high hardness and good heat conduction. However, the two are not fused, Ni is used as a transition material to prepare Ni/Mo wear-resistant coating on the surface of copper, and ensure that Ni is not excessively diluted.

I have cited the research statuse as follows:

"Some scholars have carried out some related researches on the conductive wear-resisting coating of laser cladding. Liu [7]carried out a study on H62 brass as a guide rail, which proved that the Cu guide rail had good thermal and electrical conductivity. However, it would cause serious wear, failing the Cu guide rail, it could not meet the requirements of the electromagnetic performance. In order to solve the non-wear characteristics of the Cu alloy surface. Dong[8] prepared a cobalt-based coating on the Cu alloy surface to increase the surface hardness to 600HV, which is 6 times the hardness of the copper substrate. However, carbides are formed on the surface of the coating, so pure Co layer cannot be guaranteed. In order to solve the characteristics oxidize at high temperature and Low abrasion resistance, a high-temperature resistant cermet coating is claded on the copper surface. Gu[9] chose the ceramic Pb₃O₄-B₂O-BaO-SiO₂ system to study the performance of the coating by changing the amount of Ni powder added. The results show that the coating with the addition ratio of Ni powder to glass frit of 1.2:11.0 has the best overall performance Besides, it can effectively protect the base alloy from oxidation. However, the hardness of the copper surface is not significantly increased. Yang et al.[10] added Cr, Al, Sn, Ni and other elements to the Cu alloy. Yang put Cu particles and pure metal particles into the melting furnace, vacuum and slowly flush with argon gas, performed cold deformation treatment and hardness test. The surface hardness of laser cladding was about 2 times that of Cu substrate. But the thermal conductivity is reduced. Dehm[11] et al. first coated Cu powder with Ni-based powder and deposited a Ni-B-Si plasma spraying layer on the Cu substrate. Although the surface hardness was improved, a large number of borides fractured due to high stress in the cooling process. Due to the characteristics of rapid laser cooling, cracks are prone to occur on the surface of the cladding layer. Patrick W.Leech [12] performed laser cladding on the surface of composite high-alloy steel and found that pores and cracks extended from the surface to the bottom of the collective. The cracks can be reduced by controlling the laser power and scanning speed. Florian Wirth et al.[13] established a laser cladding simulation model to predict the height and width of the cladding, so as to achieve the purpose of process optimization. V.G.Smelov et al.[14] designed a laser sintering experimental device. By establishing a fine-powder laser sintering process algorithm, defect-free samples can be obtained, thereby obtaining a sintering zone without pores and cracks. But the Technology for producing a fine powder requires the  use of expensive equipment. "

3.If the authors would clarify what is the novelty of the work in comparison with previously published Refs., they would have done the introduction comprehensible to scientists working outside the topic of the paper.

Thanks for your suggestions! The Introduction section has been sorted out and revised. Compared with the previously published literature, in this article, the Ni and Mo composite coatings are prepared on the Cu surface. Cu is not completely melted, Mo is not diluted, and the surface layer is Mo, which improved the wear resistance and ensured excellent thermal conductivity.

4.In the section 3. Results and analysis (maybe “Results and Discussion”), very little information is devoted specifically to the discussion. It might be better to supplement the article with subsection 3.6, which would fill the existing gap. It would be nice to finish this paper with some sort of future perspective on this topic. This would be very valuable for the work done here.

Thanks for your suggestions! 

The title was modified “Results and Discussion”(Page11).

"3.6.Improvements in the experience" was added. "The residual stress generated after the cladding layer is caused by the physical properties of the substrate and the cladding layer. Thermal stress can be reduced by reducing the difference in thermal expansion coefficient between the cladding layer and the substrate. Increase the toughness of the cladding layer so that it is not easy to crack under the action of stress. Because rare earth elements can reduce defects in the cladding layer and increase the hardness of the cladding layer, metal oxides can stir the molten pool under convective impact, which is beneficial to gas discharge and improve the fluidity of the molten pool. At the same time, the addition of metal oxides is equivalent to add many non-spontaneous crystal nuclei in the molten pool, increasing the nucleation rate and crystal grain size[29]. The rare earth oxide CeO₂ can increase the absorption rate of laser radiation energy[30], so that more Mo is melted into the molten pool. So it can reduce the thermal expansion difference between the Mo and the Ni layer and reduce the cracking tendency of the Mo layer."(Page11)

5. Despite the interesting content of the article, the conclusions seem too short and do not reveal details.

Thanks for your suggestions! Conclusion has been added.（Page12）

(1)By using a laser power of 6000W , the scanning speed of 5mm/s and the feed rate was 10 g/min. Three layers of Ni layer and two layers of Mo layer was cladded. Cladding layers with pure Mo on the surface can be prepared.

(2)Due to the compresensive factors such as poor fluidity of the molten pool of Mo and non-equilibrium solidification of the laser, pores and cracks are easily formed in the pure Mo layer.

(3)In order to prepare wear-resistant and high thermal conductivity coating on the Cu, Ni was introduced to overcome the incompatibility of Cu and Mo. The surface hardness of the cladding layer can be increased by 3 times than that of the substrate. The volumetric wear rate of copper is 3 times that of the cladding layer. The main wear mechanism of the Mo is abrasive wear, and the Cu is adhesive wear.  

Author Response File: Author Response.docx

Reviewer 4 Report

Defect formation mechanism and performance study of Laser Cladding Ni/Mo composite coating 

The paper presented interesting materials for discussion in the field of coatings. It can be a good reference for future works in laser cladding and composite coating.

Nevertheless, I found several matters need to be corrected and revised before the paper is announced as acceptable for publication.

1. All emails of authors need to be written in authorship. See template and guidance in Coatings | Instructions for Authors (mdpi.com)
2. Check for typos. Several parts are detected have a space between word and comma, e.g., [sssss ;]. Also, check every title of sections and sub-sections.
3. The introduction is not clear. The authors did not state what will be conducted in the research. Instead, the authors made long discussions related to pioneer works.
4. Related no. 3, I also highly recommend composing a literature review after the Introduction in an individual section.
5. The experimental section is very not clear. At least, the authors have to present figures of the specimen; instrument/apparatus; details of composite materials; substance, or entity, including where the substance was bought. etc. This section has to be rewritten, including is section title.
6. On page 6, it is mentioned a table. However, the format is incorrect. See template and guidance in Coatings | Instructions for Authors (mdpi.com)
7. Make sure all axes in graphs are given by Dimension and Unit. Several graphs are not given these details. If the unit does not exist, such as in ratio, it can be written as (-).
8. The formula needs to be stated as an equation. See template and guidance in Coatings | Instructions for Authors (mdpi.com) to see equation numbering and clarification of equation in the text.
9. Future works based on the current findings need to be stated in the Conclusions.
10. The credit authorship contribution statement has not been completed. All authors need to be assigned by all elements/job desks, including funding, supervision, etc.
11. Cite papers from Coatings, especially for the Literature Review. Pioneer works need to be arranged as a table. It is preferred that way.
12.  Fix the reference format. See template and guidance in Coatings | Instructions for Authors (mdpi.com)

Author Response

List of Responses

Dear Editors and Reviewer:

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled "Defect formation mechanism and performance study of Laser Cladding Ni/Mo composite coating " (Manuscript Number: coatings-145145). Those comments are all valuable and very helpful for revising and improving our paper, as well as the essential guiding significance to our researches. We have studied comments carefully and have made a correction, which we hope to meet with approval. The revised portion is marked in red in the paper. The leading corrections in the paper and the response to the reviewer’s comments are as flowing:

Reviewer4

The paper presented interesting materials for discussion in the field of coatings. It can be a good reference for future works in laser cladding and composite coating.

Nevertheless, I found several matters need to be corrected and revised before the paper is announced as acceptable for publication.

1."All emails of authors need to be written in authorship. See template and guidance in Coatings | Instructions for Authors (mdpi.com)"

Thanks for your comments and suggestions.Email has been added.

School of Transportation Science and Engineering, Civil Aviation University of China,

Tianjin 300300, China; [email protected](M.S.); [email protected](M.P.)

*Correspondence: [email protected](M.P.); Tel: +86-15510827880. （Page1）

Thanks again for your correction.

2. "Check for typos. Several parts are detected have a space between word and comma, e.g., [sssss ;]. Also, check every title of sections and sub-sections."

Thanks for your comments and suggestions. I am very sorry for my negligence Typos has been checked. Thanks again for your correction.

3. "The introduction is not clear. The authors did not state what will be conducted in the research. Instead, the authors made long discussions related to pioneer works."

Thanks for your comments and suggestions. I have revised the introduction. The specific content was in the introduction of the manuscript(Page1)

The main contents are as follows:

"The copper rail is the main component of the electromagnetic gun. Due to the poor wear resistance of copper, a wear-resistant coating is prepared on the copper surface. The existing methods include electroplating and cold spraying, but each has disadvantages. Laser cladding has the characteristics of small heat-affected zone, so laser cladding is used. However, due to the excellent thermal conductivity of copper, laser cladding on the copper surface has always been a difficult point. Some scholars conduct some research in order to solve the difficulties. Because laser cladding is prone to cracks, some scholars have proposed some solutions. Because Mo has good wear resistance and thermal conductivity, laser cladding Mo is used on the surface of the copper rail, and Ni is used as the transition layer. In this paper, the laser cladding Mo/Ni composite coating on the copper surface, and the defects and properties such as surface cracks are studied. "

Thanks again for your correction.

4."Related no. 3, I also highly recommend composing a literature review after the Introduction in an individual section."

Thanks for your comments and suggestions. The Introduction section has been sorted out and revised(Page1). Thanks again for your correction.

5."The experimental section is very not clear. At least, the authors have to present figures of the specimen; instrument/apparatus; details of composite materials; substance, or entity, including where the substance was bought. etc. This section has to be rewritten, including is section title."

Thanks for your comments and suggestions.The experimental has been rewritten.(Page3)

The specimens were cut by wire-cut machine (ZhongXin, Taizhou, China) in the vertical to the scanning direction. It was ground by #60 to #2000 metallographic SiC sandpapers and polished by a polish-grinding machine. Ni-Cu layer and Mo-Ni-Cu mixed area layer was etched with aqua regia, which time is 10s. Mo layer was etched with etchants ( HNO₃: HCL: HF=1:2:2). The time of corrosion is 5s.

The microstructure evolution of the single trace coatings was characterized by optical microscopy (TK-C1031EC, China) and scanning electron microscope (Phenomg5 pure，Netherlands), with the energy dispersive spectroscopy (EDS), the working distance of 52.7μm, the accelerating voltage of 15 kV and the pressure of 0.1 Pa.

The composition of the cladding layer was identified by X-ray diffractometry (Rigaku D / max-2500 / PC,Japan). XRD patterns were collected in the range of 10^◦≤2θ≤100^◦at a scanning velocity of 8^◦/min.

The room-temperature dry slide friction and wear experiments were performed in the M−2000 frictional wear tester(HengXu, Jinan, China), with the following conditions: rotating speed was 300r/min, grinding time 30 min, glide distance 84.78m, the average load 60 N. The diameter of the grinding ball is 3mm, the material is 316 stainless steel, and the hardness is 290HV. The dimension of the test specimens was 15mm×10mm×10mm. Tests 3 times per sample were completed to measure the friction coefficient and wear rate.

The microhardness of the cross-sectional of the coatings was measured with a HVS-1000Z microhardness analyzer at an applied load of 0.5 N and a dwell time of 10s. The hardness of the crosssection of the sample was tested three times from the coating surface to the substrate. The hardness test was carried out along the vertical directions at 250μm intervals, and a hardness test was carried out along the horizontal direction at 200μm. The path of the hardness point is shown in Figure 2.

Thanks again for your correction.

6."On page 6, it is mentioned a table. However, the format is incorrect. See template and guidance in Coatings | Instructions for Authors (mdpi.com)"

Table 1. Point energy spectrum analysis results of the cladding layer in different areas (wt.%)

Thanks again for your correction.

7."Make sure all axes in graphs are given by Dimension and Unit. Several graphs are not given these details. If the unit does not exist, such as in ratio, it can be written as (-)."

Thanks for your comments and suggestions. The relevant content has been corrected.(Page10)

Figure 7. The hardness of cladding layer (a)The hardness distribution from the surface of the laser cladding to the substrate.(b) The average hardness of each layer

Figure 8.The average friction coefficient (a) and wear rates (b) of coatings and matrix.  

Thanks again for your correction.

8."The formula needs to be stated as an equation. See template and guidance in Coatings | Instructions for Authors (mdpi.com) to see equation numbering and clarification of equation in the text."

9."Future works based on the current findings need to be stated in the Conclusions."

Thanks for your comments and suggestions. Future works has been introduced in 3.6(Page11)

"The residual stress generated after the cladding layer is caused by the physical properties of the substrate and the cladding layer. Thermal stress can be reduced by reducing the difference in thermal expansion coefficient between the cladding layer and the substrate. Increase the toughness of the cladding layer so that it is not easy to crack under the action of stress. Because rare earth elements can reduce defects in the cladding layer and increase the hardness of the cladding layer, metal oxides can stir the molten pool under convective impact, which is beneficial to gas discharge and improve the fluidity of the molten pool. At the same time, the addition of metal oxides is equivalent to add many non-spontaneous crystal nuclei in the molten pool, increasing the nucleation rate and crystal grain size[29]. The rare earth oxide CeO₂ can increase the absorption rate of laser radiation energy[30], so that more Mo is melted into the molten pool. So it can reduce the thermal expansion difference between the Mo and the Ni layer and reduce the cracking tendency of the Mo layer"

Thanks again for your correction.

10."The credit authorship contribution statement has not been completed. All authors need to be assigned by all elements/job desks, including funding, supervision, etc."

Thanks for your comments and suggestions.The credit authorship contribution statemen has been finished.

“Author Contributions: Conceptualization and Methodology, Ming Pang; Investigation and Validation, Min Sun. All authors have read and agreed to the published version of the manuscript.”

Funding: This work was financially supported by the National Natural Science Foundation of China (Grant No. 52075559).

Institutional Review Board Statement: Not applicable.

Informed Consent Statement: Not applicable.

Data Availability Statement: Not applicable.

Conflflicts of Interest: The authors declare no conflflict of interest. “

Thanks again for your correction.

11."Cite papers from Coatings, especially for the Literature Review. Pioneer works need to be arranged as a table. It is preferred that way."

Thanks for your comments and suggestions. 

"[22]Chun, S.-Y. Changes of Crystal Structure and Microstructure of MoN Coatings in Accordance with Inductively Coupled Plasma Power. Coatings 2021, 11, 1351. doi:org/10.3390/coatings11111351

[23]Feng, Y.; Du, Z.; Hu, Z. Effect of Ni Addition on the Corrosion Resistance of NiTi Alloy Coatings on AISI 316L Substrate Prepared by Laser Cladding. Coatings 2021, 11, 1139,doi:10.3390/coatings11091139" was cited.

12. "Fix the reference format. See template and guidance in Coatings | Instructions for Authors (mdpi.com)"

Thanks for your advice! Based on your comments, we have corrected the abbreviations of all names in the reference. At the same time, we have unified the format of the titles of the articles in the references. In the original text, we have marked the corrected references in red. The modified references are as follows:(Page12)

Ma, W.; Lu, J. Thinking and study of electromagnetic launch technology. IEEE Trans Plasma Sci 2017;45:1071e7.

Hong-bin Xie,Hui-ya Yang,Jian Yu,Ming-yu Gao,Jian-dong Shou,You-tong Fang,Jia-bin Liu,Hong-tao Wang.Research progress on advanced rail materials for electromagnetic railgun technology.J.Defence Technology,2021,17(02):429-439.

Ren, F-z.; Yin, L-t., Wang, S-s., Volinsky AA; Tian, B-h. Cyanide-free silver electroplating process in thiosulfate bath and microstructure analysis of Ag coatings. J.Trans Nonferrous Met Soc China 2013;23:3822e8, doi:10.1016/S1003-6326(13)62935-0

Zhou, Z.- Y.; Liu, X.- B.; Zhuang, S.- G. Preparation and high temperature tribological properties of laser in-situ synthesized self-lubricating composite coatings containing metal sulfides on Ti6Al4V alloy.J.Applied Surface Science,2019,481:209-218,doi:10.1016/j.apsusc.2019.03.092

Liu, X.- B; Meng, X.- J.; Liu, H.-Q.Development and characterization of laser clad high temperature self-lubricating wear resistant composite coatings on Ti-6Al-4V alloy.J.Materials and Design,2014,55:404-409,doi:10.1016/j.matdes.2013.09.038

Yang, M.-S.; Liu, X.- B.; Fan, J.-W. Microstructure and wear behaviors of laser clad Ni/Cr3C2-WS2 high temperature self-lubricant wear-resistant composite coating.J.Applied Surface Science 2012,258:3757-3762,doi:10.1016/j.apsusc.2011.12.021

Liu , G.- M; Li J; Zhang, Q.-X.; Li, B. Failure mechanism of railways for H62brass electromagnetic gun.J.Journal of Academy of Armored ForceEngineering,2013,27(05):90-94

Dong, J.; Liu. F.; Chen, S.- Y. Preparation of Co-Ni-Cu gradient coatings by CO2laser cladding on Cu plate.J.Journal of Northeastern University,2008,29(11):1581-1584.

Gu,Y.; Zhao, P.- X. Performance of novel  metal/ceramic coating on the surface of Cu alloy.J.Materials Protection, 2017, 50 (6) :22-26.

Yang, Q.-Q.; Xu, Y.; Zhao, M.-L.; Wang. B.; Shao, X.- H.;  Li,Y.-F. Effect of adding trace Cr Al Sn and Ni on the properties of Cu alloy.J. Special casting and non-ferrous alloys. 2020,40(06):690-693.

Dehm G,Medres B,Shepeleva L,et al..Microstructure and tribological properties of Ni-based claddings on Cu substrates.J.Wear,1999,225:18-26, doi:10.1016/S0043-1648(98)00347-0

Leech, Patrick W. Laser surface melting of a complex high alloy steel. J.Materials and Design, 2014, 54:539-543, doi:10.1016/j.matdes.2013.08.060

F Wirth, Wegener K. A physical modeling and predictive simulation of the laser cladding process.J. Additive Manufacturing, 2018, 22:307-319,doi:10.1016/j.addma.2018.05.017

Smelov V G, Sotov A V, Murzin S P. Particularly Selective Sintering of Metal Powders by Pulsed Laser Radiation. J. Key Engineering Materials, 2016, 685:403-407,doi:10.4028/www.scientific.net/KEM.685.403

Xue, K.-N.; Lu, H.-F.; Luo, K.-Y.; Cui, C.-Y.; Yao, J.-H.; Xing, F.; Lu, J.-Z. Effects of Ni25 transitional layer on microstructural evolution and wear property of laser clad composite coating on H13 tool steel.J. Surface and Coatings Technology,2020(prepublish),doi:10.1016/j.surfcoat.2020.126488

10. Okamoto,T. B. Massalski. Binary alloy phase diagrams requiring further studies.J. Journal of Phase Equilibria,1994,15(5),doi:10.1007/BF02649400

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear Authors,

In the future, you should use optimization techniques to improve cladding optimization.

Reviewer 2 Report

Manuscript improved and accepted in present form

Reviewer 3 Report

Authors have addressed all the comments made by the reviewer. In my opinion, the paper is suitable for publication.

Reviewer 4 Report

All recommendations have been addressed in the revision.