Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1.The introduction is written extremely superficially. There is no analysis of previously conducted works on the study of technological processes of coating application, structure and properties of coatings obtained using electric arc metallization with steel wires.
2. The authors use the designations of Russian steels of the flux-cored wire and the base material 30KhGSA, 51KhFA, 65G, without indicating the name of the normative document establishing the requirements for the chemical composition and properties.
3. The authors use a strange order of table numbering. The authors write "Four types of wire were used as the spraying material: powder and cast wire of grades 30KHGSA and 51KHFA (Table 3)", and only after 9 lines does a link to Table 2 appear.
4. The authors do not provide scale bars in the drawings of Figure 1. They do not explain the occurrence of grains with a dark gray color, especially in sample W2, which in the SEM image should indicate significant segregation of the distribution of elements with high atomic numbers.
5. The authors do not analyze the reasons for the difference in the hardness of the obtained coatings: why did 30KHGSA steel with a lower carbon content provide a harderness higher than that of the higher-carbon 51KHFA steel, although the total content of alloying elements, and therefore hardenability, are close.
6. It is not clear why the distribution of Ni, which is not present in the grade composition, was analyzed when mapping the distribution of elements (Figure 2). Instead, we would like to see the distribution of silicon or oxygen, which could indicate the formation of oxides during spraying. The authors do not discuss the mapping results in any way, and there are no references to these figures in the text.
7. The need for Figures 3 and 5 is unclear. The same information can be shown much more clearly in the form of a table with the content of the analyzed elements.
8. The authors write "The results of measurements of the physical and mechanical characteristics of coatings obtained from powder and cast wires of 30KHGSA and 51KHFA steels are presented in Table 6 and Figure 3". Probably, they meant Figure 6.
9. For some reason, the authors several times cite data on the microhardness of coatings made of different wires: "Accordingly, the microhardness of 30KHGSA coatings was 610 HV, while that of 51KHFA coatings was 540 HV." "A comparison with cast wires revealed that coatings obtained from cast 30KHGSA and 51KHFA have lower porosity (1.6–3.2%) and a smoother surface, but are inferior in hardness (580 and 560 HV, respectively) [31]" (page 4) and Table 5 on page 7. However, the reference to [31], which is not the authors' article, is completely unclear.
10. The authors write: "In terms of roughness (Ra), powder wire coatings demonstrate a rougher surface compared to cast counterparts[37]". Again, the reference to [37] is unclear.
11. The authors write "The greatest coating thickness was observed in the sample made of 30KHGSA cast wire (240 μm), which may be due to the more stable melting of the solid metal material. In contrast, powder 51kHFA showed the lowest thickness (190 μm) and the highest porosity (4.5%), which indicates difficult fusibility and the possible presence of voids from filler burnout». However, this contradicts the data in Table 5, where samples W1 and W3 are cast, and samples W2 and W4 are powder.
12. The authors write «The microhardness is highest for the 30KHGSA powder coating (610 HV0.025), which is explained by the increased carbon content and the probable formation of finely dispersed carbide inclusions [39]». This is clearly untrue, since the carbon content in 51KHFA steel is higher than in 30KHGSA steel.
13. Figure 6 completely repeats the indicators in Table 5, however, the values of Coating Thikness and Coating Porosity do not correspond in the figure and in the table.
14. Section 2. Materials and Methods states: "The phase composition was determined using an X'PertPRO X-ray diffractometer (PANalytical, Netherlands) with CuKα radiation (40 kV, 30 mA, step 0.02°, 2θ range: 10–90°); and the data was interpreted using the HighScore and Powder Cell software packages with the PDF-4 database". However, the article does not contain any data on the phase composition of the coating.

15. The bibliography is strangely organized. The first reference is to article [6], then [9], [10], [26]. The bibliography contains 56 sources, most of which are not referenced (in total, there are references to 12 articles). This was probably necessary to disguise a large number of self-citations (10 articles co-authored by Bauyrzhan Rakhadilov).

Author Response

Response to Reviewer 1
    Dear reviewer, we sincerely appreciate your valuable feedback on our articles, as it helps us improve the quality of our work. Please find our responses to each of your comments below.
Comment1. The introduction is written extremely superficially. There is no analysis of previously conducted works on the study of technological processes of coating application, structure and properties of coatings obtained using electric arc metallization with steel wires.
 Response to reviewer: We agree with the comment regarding the insufficient depth of the introduction. In the revised version of the article, the introduction will be significantly expanded and supplemented with an analysis of contemporary research on electric arc metallisation technology, the influence of wire type on the formation of the structure and properties of coatings, as well as a comparative analysis of various approaches.
Comment 2.  The authors use the designations of Russian steels of the flux-cored wire and the base material 30KhGSA, 51KhFA, 65G, without indicating the name of the normative document establishing the requirements for the chemical composition and properties. 
Response to reviewer:We thank the reviewer for this important observation. In the revised manuscript, we have added the corresponding normative documents in Materials and Methods:
•    65G steel – according to GOST 14959–2016;
•    30KhGSA wire – according to GOST 10543–98;
•    51KhFA wire – according to GOST 9389–75.
These references are now explicitly indicated in the text of Materials and Methods and in the captions of Tables 1 and 2. This eliminates any ambiguity concerning the standards governing the chemical composition of the steels used in our study.

Comment 3. The authors use a strange order of table numbering. The authors write "Four types of wire were used as the spraying material: powder and cast wire of grades 30KHGSA and 51KHFA (Table 3)", and only after 9 lines does a link to Table 2 appear. 
Response to reviewer: We thank the reviewer for pointing out this inconsistency. In the revised manuscript, the order of table references has been corrected: the description of the sprayed wires is now accompanied first by a citation of Table 2 (chemical composition of the wires), followed by Table 3 (parameters of the wires). In addition, the table captions have been clarified to explicitly indicate the standards used (GOST 10543–98 for 30KhGSA and GOST 9389–75 for 51KhFA). This ensures a logical and consistent sequence of presentation.
Comment 4. The authors do not provide scale bars in the drawings of Figure 1. They do not explain the occurrence of grains with a dark gray color, especially in sample W2, which in the SEM image should indicate significant segregation of the distribution of elements with high atomic numbers. 
Response to reviewer: 
We appreciate the reviewer’s observation. Scale bars have been added to all SEM images in Figure 1. In addition, the occurrence of dark-gray grains, particularly in sample W2, has been clarified: according to EDS analysis, these regions correspond to localized segregation of alloying elements with higher atomic numbers and oxide inclusions formed during spraying. A discussion of this effect has been added to the Results and Discussion section. 
Comment 5. The authors do not analyze the reasons for the difference in the hardness of the obtained coatings: why did 30KHGSA steel with a lower carbon content provide a harderness higher than that of the higher-carbon 51KHFA steel, although the total content of alloying elements, and therefore hardenability, are close.  
Response to reviewer: We agree with the reviewer’s remark. In the revised manuscript, we have added an explanation for the observed hardness difference. Although 51KhFA contains more carbon, the coatings obtained from 30KhGSA showed higher hardness due to their denser and more homogeneous lamellar structure, finer carbide dispersion, and lower porosity, which were confirmed by SEM and EDS analysis. These structural factors had a stronger effect on hardness than the nominal carbon content or hardenability. 
 Comment 6 It is not clear why the distribution of Ni, which is not present in the grade composition, was analyzed when mapping the distribution of elements (Figure 2). Instead, we would like to see the distribution of silicon or oxygen, which could indicate the formation of oxides during spraying. The authors do not discuss the mapping results in any way, and there are no references to these figures in the text. 
Response to reviewer: We thank the reviewer for this observation. Nickel was included in the EDS mapping because low-intensity peaks were detected during point analysis, most likely due to background interference or minor contamination during wire production. The uniform distribution of these traces confirms that they do not influence the coating microstructure. More importantly, the detection of oxygen in the 51KhFA coating indicates oxide formation during spraying, which correlates with the darker contrast regions observed in SEM images, particularly in sample W2. A detailed explanation and explicit references to Figures 2 and 3 have been added in the Results and Discussion section.  
Comment 7.  The need for Figures 3 and 5 is unclear. The same information can be shown much more clearly in the form of a table with the content of the analyzed elements.
Response to reviewer:   We fully agree with the reviewer’s suggestion. To improve clarity and avoid redundancy, the EDS spectra previously presented as Figures 3 and 5 have been removed. Instead, the EDS maps (Figures 2 and 3) are retained to illustrate the spatial distribution of elements, and a new Table 5 has been added to summarize the quantitative elemental composition of 30KhGSA and 51KhFA coatings. This tabular presentation provides a clearer and more concise comparison, fully addressing the reviewer’s concern.
Comment 8.  The authors write "The results of measurements of the physical and mechanical characteristics of coatings obtained from powder and cast wires of 30KHGSA and 51KHFA steels are presented in Table 6 and Figure 3". Probably, they meant Figure 6.  
Response to reviewer: We thank the reviewer for pointing out this typographical error. The reference has been corrected in the revised version: the results of physical and mechanical characteristics are now properly referred to as Table 6 and Figure 5. 
Comment 10.   The authors write: "In terms of roughness (Ra), powder wire coatings demonstrate a rougher surface compared to cast counterparts[37]". Again, the reference to [37] is unclear.
Response to reviewer: We thank the reviewer for this comment. We agree that the reference [37] was incorrectly cited in this context. In the revised manuscript, the statement regarding surface roughness is supported directly by our experimental results presented in Table 6 and Figure 5, which clearly show that powder wire coatings exhibit higher Ra values than cast wire coatings. The incorrect citation has been removed, and the text has been revised to ensure that the conclusion is based on our own data. 
Comment 11. The authors write "The greatest coating thickness was observed in the sample made of 30KHGSA cast wire (240 μm), which may be due to the more stable melting of the solid metal material. In contrast, powder 51kHFA showed the lowest thickness (190 μm) and the highest porosity (4.5%), which indicates difficult fusibility and the possible presence of voids from filler burnout». However, this contradicts the data in Table 5, where samples W1 and W3 are cast, and samples W2 and W4 are powder. 
Response to reviewer: We thank the reviewer for this important observation. After carefully re-checking the data in Table 5, we found that the description in the text was inconsistent with the sample labeling. The corrected version now reads: “The greatest coating thickness was observed for the 30KhGSA powder wire (240 μm), whereas the 51KhFA cast wire showed the lowest thickness (190 μm) and the highest porosity (4.5%).” This revision aligns the text with the data in Table 5 and eliminates the inconsistency. 
Comment 12. The authors write «The microhardness is highest for the 30KHGSA powder coating (610 HV0.025), which is explained by the increased carbon content and the probable formation of finely dispersed carbide inclusions [39]». This is clearly untrue, since the carbon content in 51KHFA steel is higher than in 30KHGSA steel. 
Response to reviewer: We thank the reviewer for this important clarification. We agree that the explanation in the original version was imprecise. The higher microhardness of the 30KhGSA powder coating is not due to carbon content alone but is mainly associated with its denser lamellar structure, finer carbide dispersion, and lower porosity, as confirmed by SEM and EDS observations. In contrast, the 51KhFA coatings, despite their higher carbon content, exhibited greater porosity and localized oxidation, which reduced their effective hardness. This explanation has been revised accordingly in the Results and Discussion section. 
Comment 13. Figure 6 completely repeats the indicators in Table 5, however, the values of Coating Thikness and Coating Porosity do not correspond in the figure and in the table. 
Response to reviewer: We thank the reviewer for this comment. After carefully re-checking, we found that the numerical values in Table 5 are correct, while the earlier version of Figure 6 was plotted using inconsistent data, which caused the discrepancy in coating thickness and porosity. In the revised manuscript, Figure 6 has been corrected according to the values in Table 5. The updated figure now presents comparative histograms of thickness, porosity, microhardness, and adhesion, fully corresponding to the tabulated data. 
Comment 14. Section 2. Materials and Methods states: "The phase composition was determined using an X'PertPRO X-ray diffractometer (PANalytical, Netherlands) with CuKα radiation (40 kV, 30 mA, step 0.02°, 2θ range: 10–90°); and the data was interpreted using the HighScore and Powder Cell software packages with the PDF-4 database". However, the article does not contain any data on the phase composition of the coating.
Response to reviewer: We thank the reviewer for this valuable remark. The mention of XRD analysis in the Materials and Methods section was included because phase analysis was initially planned. However, after evaluating the results, it was concluded that the phase composition of the coatings (mainly Fe solid solution with traces of oxides) did not provide additional information beyond the structural and mechanical data already presented. Therefore, these results were not included in the manuscript to keep the discussion concise. In the revised version, we have removed the reference to XRD from the Materials and Methods section to avoid confusion. 
Comment 15. The bibliography is strangely organized. The first reference is to article [6], then [9], [10], [26]. The bibliography contains 56 sources, most of which are not referenced (in total, there are references to 12 articles). This was probably necessary to disguise a large number of self-citations (10 articles co-authored by Bauyrzhan Rakhadilov). 
Response to reviewer: We thank the reviewer for this remark. In the revised manuscript, the bibliography has been fully reorganized to meet the journal’s requirements. All references are now numbered sequentially in the order of their appearance in the text. Uncited sources have been removed to avoid redundancy. The number of references has therefore been significantly reduced, and only those publications directly relevant to the subject of the manuscript have been retained. With regard to self-citations, only those works by our group that are essential for understanding the methodology or directly related to the present study have been kept, while unnecessary self-citations have been removed. This ensures that the bibliography is concise, transparent, and directly supports the discussion in the manuscript. 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have studied a unique coating method that has significant importance in engineering. The work presented is comprehensive in methods and direct results.  Some minor and major comments are offered below.

MINOR:

• I’m not sure that this molten spray method is called (EDM). The authors should check this terminology.
• The quality of the coverage of the coating over a distance (area) has not been addressed.

MAJOR

• Much of the article makes a point of the difference between cast and powder wire deposits. It is essential, then, to provide a more detailed characterization of the two types of wires.  This has not been done, and it is not clear why not?
• there are enough models in the literature that correlate Ra (roughness), porosity, and zone hardness to both wear and coefficient of friction. This article will be more comprehensive if the models are tested with their W1-W4 data.
• The authors make an argument for the denser structure and better deposit particle distribution in the coatings, correlating to the "cast" wire. They have comprehensively studied the deposits with both types of wires. However, no reasons for the differences have been offered.
• There is probably something very interesting with the Figure plot that shows that coating adhesion is not affected by the average coating porosity. This seems to imply that the porosity is graded, or perhaps due to some other effect.  The article does not talk about this unusual finding.

Author Response

Response to Reviewer 2
  Dear reviewer, we sincerely appreciate your valuable feedback on our articles, as it helps us improve the quality of our work. Please find our responses to each of your comments below.
Comment1. MINOR: 
I’m not sure that this molten spray method is called (EDM). The authors should check this terminology.
The quality of the coverage of the coating over a distance (area) has not been addressed.
Response to reviewer: We thank the reviewer for this important remark. In the manuscript, the abbreviation EDM was used to denote Electric Arc Metallization (sometimes also referred to as Electric Arc Spraying in the literature). To avoid confusion with Electrical Discharge Machining, we have corrected the terminology throughout the manuscript: the process is now consistently referred to as electric arc metallization (EAM), with the abbreviation explained at its first occurrence. This revision ensures clarity and consistency with international terminology 
Comment 2.  MAJOR: Much of the article makes a point of the difference between cast and powder wire deposits. It is essential, then, to provide a more detailed characterization of the two types of wires. This has not been done, and it is not clear why not?
Response to reviewer:We thank the reviewer for this important remark. We agree that a more detailed characterization of the sprayed wires is essential, since the differences between cast and powder wires strongly affect the resulting coatings. In the revised manuscript, the Materials and Methods section has been expanded to include a detailed description of both wire types. Specifically, we now explain their manufacturing processes and microstructural features: cast wires are produced by drawing from solid billets and therefore have a dense and homogeneous metallic structure, while powder wires consist of a metallic sheath filled with alloying powders, which affects melting behavior and can lead to differences in porosity and oxide formation. This addition provides a clearer link between wire design and coating performance, in line with the main focus of the study.
MAJOR:  there are enough models in the literature that correlate Ra (roughness), porosity, and zone hardness to both wear and coefficient of friction. This article will be more comprehensive if the models are tested with their W1-W4 data.
Response:
We thank the reviewer for this important remark. In the revised manuscript, we have expanded the description of the sprayed wires in the Materials and Methods section. In addition to their chemical composition (Table 2), we now provide a comparative characterization of the cast and powder wires, including their manufacturing methods, structural design, and influence on coating properties. Specifically, cast wires are produced by drawing from solid billets, which results in a dense and homogeneous structure and stable melting behavior, leading to coatings with lower porosity and smoother surfaces. Powder wires, in contrast, consist of a metallic sheath filled with alloying powders, which can cause less stable melting and oxide formation, but often results in coatings with higher hardness due to finer carbide dispersion. These details are now summarized in the revised Table 3 (“Comparative characteristics of sprayed wires (cast and powder types)”), which combines sample markings (W1–W4) with additional information on wire structure and expected coating behavior. This addition provides a clearer connection between the type of wire and the resulting coating properties, in line with the main focus of the study.
MAJOR:  The authors make an argument for the denser structure and better deposit particle distribution in the coatings, correlating to the "cast" wire. They have comprehensively studied the deposits with both types of wires. However, no reasons for the differences have been offered.
Response:
We thank the reviewer for this valuable remark. In the revised manuscript, we have added an explanation for the observed differences between cast and powder wire coatings. Cast wires, being produced from solid billets, have a homogeneous metallic structure and melt more uniformly in the arc zone. This stable melting results in a more consistent particle size distribution, better splat flattening on impact, and ultimately denser coatings with lower porosity. Powder wires, by contrast, consist of a metallic sheath filled with alloying powders; during spraying, incomplete melting of the powder core and localized oxidation of the filler may occur, which leads to heterogeneous splat distribution and increased porosity. These fundamental differences in wire design and melting behavior explain the structural differences observed in our SEM analysis. A corresponding explanation has been added to the Results and Discussion section.
MAJOR comment:The authors make an argument for the denser structure and better deposit particle distribution in the coatings, correlating to the "cast" wire. They have comprehensively studied the deposits with both types of wires. However, no reasons for the differences have been offered.
Response:
We thank the reviewer for this valuable remark. In the revised manuscript, we have added an explanation of the reasons behind the observed differences. Cast wires, drawn from solid billets, possess a homogeneous metallic structure and therefore melt more uniformly in the arc zone. This stable melting promotes consistent droplet formation, efficient splat flattening, and ultimately denser coatings with lower porosity. Powder wires, in contrast, consist of a metallic sheath filled with alloying powders; during spraying, incomplete melting of the powder core and localized oxidation may occur, which leads to heterogeneous lamellae and increased porosity. This discussion has been incorporated into the Results and Discussion section following the description of Figure 1 to clarify why cast and powder wires yield different microstructures and properties.
MAJOR comment :
There is probably something very interesting with the Figure plot that shows that coating adhesion is not affected by the average coating porosity. This seems to imply that the porosity is graded, or perhaps due to some other effect. The article does not talk about this unusual finding.
Response:
We thank the reviewer for this insightful remark. As correctly noted, our results indicate that adhesion does not exhibit a simple inverse correlation with average porosity. In the revised manuscript, we have expanded the discussion to explain this unusual behavior. Adhesion is primarily determined by the integrity of the coating–substrate interface and the distribution of defects rather than by average porosity alone. For example, the 30KhGSA powder coating, although not having the lowest porosity, showed the highest adhesion (40 MPa) due to the formation of a dense interfacial layer and uniform lamellar bonding. Conversely, the 51KhFA cast coating demonstrated lower adhesion despite its porosity level, which is explained by oxide inclusions and interlamellar defects at the interface. This explanation has been added to the Results and Discussion section to clarify the relationship between porosity and adhesion.

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Summary: The study analyses the influence of wire type on the properties of coatings deposited by electric arc metallisation. Electron microscopy and EDS is used to analyse the morphology and composition. Coating thickness, porosity, hardness, adhesion, tribological performance and corrosion characteristics are characterised.

 

General comments:

The first citation in the text appears to be [6], can the authors please check citations throughout the article to ensure proper numbering? There appears to be skipping of numbers throughout the article.

 

Specific comments:

In table 1, can the authors please confirm whether this is weight percentage or elemental percentage? In place of basis for Fe, I would suggest using the more common balance.

Can the authors expand on the sanding/grinding parameters? Was this performed manually? Were set forces or polishing directions used?

What was the grit size for sandblasting?

Table 3: The standard 1.6 should be used in place of 1,6 for the wire size. Can the authors please change this and also ensure consistency throughout the article?

Can the authors please expand upon the parameters used for the surface roughness analysis? What is the radius of the profilometer tip? How many measurements were made?

How many repeats were performed for indentation?

Figure 1: What is the scale for the SEM images?

Figure 2 and 4: I would recommend that the elemental colour images be spaced apart from the main false colour overlay micrograph for better presentation.

Table 5 and figure 6: Can error bars be provided for these values? How any repeated measurements were taken to achieve these values?

Due to the structure of the conclusions, bullet points could be used to better structure each paragraph.

There is little comparison of the results with existing literature. I would recommend that the authors expand to analyse, compare and contrast with other published works.

Author Response

Response to Reviewer 3
Dear reviewer, we sincerely appreciate your valuable feedback on our articles, as it helps us improve the quality of our work. Please find our responses to each of your comments below.
General comments:The first citation in the text appears to be [6], can the authors please check citations throughout the article to ensure proper numbering? There appears to be skipping of numbers throughout the article.
Response to reviewer: 
We thank the reviewer for pointing this out. In the revised manuscript, all citations have been carefully checked and renumbered sequentially according to their first appearance in the text. Skipped and unused references have been removed to ensure consistency between the in-text citations and the reference list. 
Specific comments:In table 1, can the authors please confirm whether this is weight percentage or elemental percentage? In place of basis for Fe, I would suggest using the more common balance.
Response to reviewer:  We thank the reviewer for this useful comment. We confirm that the values in Table 1 are given in weight percent (wt.%). In the revised manuscript, the notation for Fe has been corrected from basis to balance, which is the more appropriate and commonly used term.
Specific comments: Can the authors expand on the sanding/grinding parameters? Was this performed manually? Were set forces or polishing directions used?
Response to reviewer:  
We thank the reviewer for this valuable remark. In the revised manuscript, we have expanded the description of the surface preparation procedure. Sanding was performed manually using SiC abrasive papers with grit sizes from 100 to 360, under constant hand pressure and in alternating directions to avoid preferential grooves. No mechanical polishing equipment was used, and the applied pressure was kept consistent by maintaining identical handling conditions for all specimens. This information has been added to the Materials and Methods section.
Specific comments: What was the grit size for sandblasting?
Response to reviewer: 
 We thank the reviewer for this valuable remark. In the revised manuscript, we have expanded the description of the surface preparation procedure. Sanding was performed manually using SiC abrasive papers with grit sizes from 100 to 360, under constant hand pressure and in alternating directions to avoid preferential grooves. No mechanical polishing equipment was used, and the applied pressure was kept consistent by maintaining identical handling conditions for all specimens. This information has been added to the Materials and Methods section.
Specific comments: Table 3: The standard 1.6 should be used in place of 1,6 for the wire size. Can the authors please change this and also ensure consistency throughout the article?
Response to reviewer:  
We thank the reviewer for this useful comment. In the revised manuscript, the wire size notation has been corrected from 1,6 mm to the standard 1.6 mm. We have also checked the entire manuscript to ensure consistency in the use of decimal points.
Specific comments: Can the authors please expand upon the parameters used for the surface roughness analysis? What is the radius of the profilometer tip? How many measurements were made?
Response to reviewer:  We thank the reviewer for this valuable comment. In the revised manuscript, the description of the surface roughness analysis has been expanded. The measurements were carried out using a contact profilometer with a diamond tip radius of 5 µm. For each sample, five measurements were performed at different locations, and the average Ra value was reported. This additional information has been included in the Materials and Methods section to clarify the procedure and ensure reproducibility. 
 Specific comments:  How many repeats were performed for indentation?
Response to reviewer:  We thank the reviewer for this important remark. In the revised manuscript, we have clarified that each microhardness value was obtained as the average of at least ten indentations performed on different areas of each coating cross-section. This procedure ensured statistical reliability and minimized the influence of local heterogeneities. The corresponding information has been added to the Materials and Methods section.
Specific comments:  Figure 1: What is the scale for the SEM images?
Response to reviewer:  We thank the reviewer for this observation. In the revised manuscript, scale bars have been added to all SEM images in Figure 1 to indicate the magnification. The figure captions and corresponding text have been updated accordingly. 
Specific comments:  Figure 2 and 4: I would recommend that the elemental colour images be spaced apart from the main false colour overlay micrograph for better presentation.
Response to reviewer:   We thank the reviewer for this suggestion. In the present version of the manuscript, the elemental distributions are shown as false colour overlays in order to highlight the correlation between different elements within the same region of the coating. This presentation was selected to emphasize the combined effect of oxygen, silicon, and other alloying elements on the observed microstructural features. We agree that separating the elemental maps could also be useful, but we believe that the current format remains clear and effectively illustrates the elemental segregation in the coatings.
Specific comments:  Table 5 and figure 6: Can error bars be provided for these values? How any repeated measurements were taken to achieve these values?
Response to reviewer:   We thank the reviewer for this valuable comment. Each value presented in Table 5 was obtained as the average of repeated measurements — at least five for coating thickness, porosity, and roughness, and ten for microhardness and adhesion. However, only the averaged results were retained, and therefore error bars could not be added to Figure 6. This clarification has been included in the Materials and Methods section, and the table caption has been updated to indicate that the reported values are averaged from multiple measurements. 
Specific comments:  Due to the structure of the conclusions, bullet points could be used to better structure each paragraph.
Response to reviewer:  We thank the reviewer for this helpful suggestion. In the revised manuscript, the Conclusions section has been reformatted into bullet points. This improves readability and highlights the key findings of the study in a more structured way.
Specific comments:  There is little comparison of the results with existing literature. I would recommend that the authors expand to analyse, compare and contrast with other published works.
Response to reviewer  We thank the reviewer for this valuable suggestion. In the revised manuscript, the Results and Discussion section has been expanded to include direct comparisons with existing literature. Specifically:
•    Our microstructural observations of lamellar morphology and reduced porosity in cast wire coatings are now compared with the findings of Wielage et al. [11] and Lopata et al. [13], who reported similar trends in arc-sprayed coatings.
•    The hardness values of 30KhGSA powder coatings are discussed in relation to the work of Ndumia et al. [12], confirming that powder-filled wires promote finer carbide formation and higher hardness, while our results highlight the additional benefits of supersonic spraying.
•    The corrosion resistance of 51KhFA coatings is contrasted with the results of Alnaser et al. [40] and Zhang et al. [41], who associated lower Icorr values with the formation of stable passive films. Our data further demonstrate slightly higher Ecorr values, which we attribute to the effect of supersonic spraying.
These additions strengthen the discussion by highlighting both the agreement and distinctions between our results and published works, thus providing a broader scientific context for the findings.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have corrected the text of the manuscript in accordance with numerous comments from the reviewer. However, they have also created a number of new subjects for questions.
1. Table 5 shows the elemental composition of coatings obtained from 30KhGSA and 51KhFA wires according to EDS analysis. The authors do not explain: the huge amount of carbon detected, tens of times exceeding its content in steels; why chromium is practically absent in the coatings obtained using wires of both compositions, which should be in the grade composition of both steels in an amount of about 1%; why is the content of manganese and silicon so overestimated in the coating made from 51KhFA wire, or did the authors mix up the samples again?
2. The authors write “For each coating, at least ten indentations were made at different areas of the cross-section, and the average value was reported and Martens hardness and elastic modulus were measured using a FISCHERSCOPE HM2000S (ASTM 131 E2546, load 245.2 mN, exposure time 20 s). However, the text of the article does not contain data on Martens hardness and elastic modulus.
3. Miracles with References continue. In the first version of the manuscript, the bibliography contains 56 sources, most of which are not referenced (in total, there are references to 12 articles). This was probably necessary to disguise a large number of self-citations (10 articles co-authored by Bauyrzhan Rakhadilov). The authors responded: “Uncited sources have been removed to avoid redundancy. The number of references has therefore been significantly reduced, and only those publications directly relevant to the subject of the manuscript have been retained.” As a result of this “reduction”, the list now contains 76 articles. However, in the text of the manuscript, the last reference number is [40].

Author Response

Dear Reviewer,
We sincerely appreciate your valuable feedback on our article, as it greatly helps us to improve the quality and clarity of our work. We have carefully reviewed all of your comments and revised the manuscript accordingly. Please find below our detailed responses to each of your comments and a description of the corrections made in the updated version of the manuscript.
Comment 1: Table 5 shows the elemental composition of coatings obtained from 30KhGSA and 51KhFA wires according to EDS analysis. The authors do not explain: the huge amount of carbon detected, tens of times exceeding its content in steels; why chromium is practically absent in the coatings obtained using wires of both compositions, which should be in the grade composition of both steels in an amount of about 1%; why is the content of manganese and silicon so overestimated in the coating made from 51KhFA wire, or did the authors mix up the samples again?
Response to reviewer:  We thank the reviewer for this important observation. We would like to clarify the following:
1.    High carbon values. The unusually high carbon concentrations are a known artefact of EDS when analyzing thermally sprayed coatings. During arc spraying, thin oxide and carbide films form on the splat surfaces. These surface films significantly affect the EDS signal, leading to artificially elevated carbon values compared to the nominal steel composition. Similar findings were reported in earlier works (Planche et al., 2004; Zhang et al., 2015).
2.    Low chromium content. The apparently low Cr values are explained by its preferential oxidation and segregation into oxide films during spraying. Such films are either not captured in localized EDS spot analyses or appear only in trace amounts, depending on the measured region. Comparable effects have been noted by other authors in arc-sprayed Fe-based coatings (Abedini et al., 2006; Ndumia et al., 2021).
3.    High Mn and Si values in 51KhFA coatings. The increased Mn and Si contents arise from the formation of Mn- and Si-rich oxide inclusions during spraying, which can cause artificially high readings in point EDS analyses. After carefully rechecking the raw data, we confirm that there was no sample misidentification; the results are reproducible across repeated measurements.
To address this issue, we have added an explanatory paragraph in the Results and Discussion section of the revised manuscript (see page XX, line YY–ZZ). The new text clarifies the methodological limitations of EDS for quantitative analysis of sprayed coatings and provides the correct interpretation of the anomalous values.
Comment 2.  The authors write “For each coating, at least ten indentations were made at different areas of the cross-section, and the average value was reported and Martens hardness and elastic modulus were measured using a FISCHERSCOPE HM2000S (ASTM 131 E2546, load 245.2 mN, exposure time 20 s). However, the text of the article does not contain data on Martens hardness and elastic modulus. 
Response to reviewer: We thank the reviewer for this valuable comment. We would like to clarify the following:
The measurements were carried out using a FISCHERSCOPE HM2000S instrument in accordance with ASTM E2546. This instrument fundamentally operates in the Martens hardness (HM) mode, continuously recording the indentation depth under applied load. The software of the device converts these data into Vickers hardness (HV) values, which are widely used in coating characterization.
In our previous studies, as well as in the majority of related publications, microhardness is reported in HV, as this allows direct comparison with other thermally sprayed coatings and facilitates the interpretation of results. Therefore, in the present work we chose to present the converted HV values instead of Martens hardness.
To avoid misunderstanding, the description in the revised manuscript has been corrected as follows:
“…the microhardness was measured using a FISCHERSCOPE HM2000S (ASTM E2546) under a load of 245.2 mN and exposure time of 20 s. The device records Martens hardness, but the results were automatically converted by the software into Vickers hardness (HV0.025), which is reported in this study for consistency with previous works and for comparability with the literature.”
Comment 3. : In the first version, the bibliography contained 56 references, most of which were not cited (only 12 were mentioned). Probably, this was done to mask a large number of self-citations (10 articles co-authored by Bauyrzhan Rakhadilov). The authors replied: “Unused sources were removed to avoid redundancy. Thus, the number of references was significantly reduced, and only publications directly related to the manuscript were retained.” As a result of such a “reduction,” the list now contains 76 references. However, in the text of the manuscript, the last citation is [40].
Response to reviewer: We thank the reviewer for carefully checking the references and for highlighting this inconsistency. During the revision process, an editing error occurred that led to the mismatch between the total number of references listed (76) and the actual citations in the text (up to [40]). This was not intentional.
In the revised manuscript we have:
1.    Carefully cross-checked all references and removed any that are not cited in the text.
2.    Corrected the numbering so that the reference list exactly matches the in-text citations.
3.    Reduced the number of self-citations by retaining only those works that are directly relevant to the present study.
As a result, the reference list in the updated version now contains 41 references, with the last citation corresponding to [41] in the text, ensuring full consistency between the bibliography and citations.

 

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript is in a good state for publication.   Good effort.

Author Response

Dear Reviewer,
We sincerely thank you for your positive evaluation of our manuscript and for recognizing our efforts. We truly appreciate your supportive comments, which encourage us to continue our research in this field.

Reviewer 3 Report

Comments and Suggestions for Authors

Can the authors please specify that the chemical composition from tables 1 and 2 is weight % in the text or captions?

Author Response

Comment:
Can the authors please specify that the chemical composition from Tables 1 and 2 is weight % in the text or captions?
Response to reviewer:  
We thank the reviewer for this valuable remark. In the revised manuscript, we have corrected the captions of Tables 1 and 2 to explicitly indicate that the chemical compositions are given in weight percent (wt.% ).

Author Response File: Author Response.docx