Effect of Brazing Temperature on Microstructure and Properties of WC-10Ni + AgCuTi Composite Coatings

Round 1

Reviewer 1 Report

35: correct- whole[1][2]. in whole [1,2].

40: correct- the like[3][4]. in the like [3,4]. et al.[5] in at al. [5] Al2O3 in Al₂O₃

_{44: correct al[6]. in al. [6].}

_{47: [7]prepared in [7] prepared}

_{50: years[8]. in years [8].}

_{55: put other standard for a 45# steel}

_{59: correct surface[10][11]. in surface [10,11].}

Author Response

Dear Reviewer,

Thank you very much for your valuable comments. We have made changes based on your comments.

Kind regards,

Yi Wang

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper presents a study of brazing WC-composite coatings on top of copper subtracts. For all samples, the brazing temperature was varied and the microstructure of the specimens, the phase composition, and the hardness were studied.

The paper is easy to follow. However, I can't suggest the publication in the current state because it lacks in-depth assessment of the samples, as discussed in the following:

- As shown in Fig. 2 and 3, the microstructure of the studied samples is very heterogeneous. Therefore, a careful assessment of the repeatability of the specimens and the variation in each specimens is vital to this study: How good is the repeatability for different samples? This includes information of how many specimens were used for each brazing temperature and how many line scans were performed. Especially the information of the variation in hardness is important to understand Fig.8: Are the shown values the mean values of the hardness and how large is the variation for different hardness line scans? Plotting additional error bars would be helpful in Fig. 8.

- It is unclear at which position the phase composition and the line-scans were performed. Were samples investigated only in the centre of the specimens?

- Section 2 is partly not understandable: It is unclear what "repeatedly rolled into tape shape" means. How was the coating finally applied to the substrate and what is the final thickness of the coating?

- It is said that the surface of the copper plates were ground before applying the coating - What is the necessary roughness for bounding the coating or was that step performed to remove an oxide layer?

- The hardness was measured by micro-hardness testing. What was the applied force and the area of the indent? This information is crucial to understand if the hardness values are actually a mean value over a larger tested volume or if single WC-particles were indented which have a diameter of roughly 20 microns.

- The XRD peaks in Fig. 6 are looking very similar for different brazing temperature - e.g. why is the third peak from the left defined at 830C as Ni4Ti3, at 860C as beta-Ti, at 890C as CuTi, and at 920C as Ag? I don't see a large change in those peaks over the brazing temperature.

Minor issues to address:

- The colours in Fig. 5 are changing in (b, d, f, h) for the same elements which is very confusing for the reader.

- Carefully check spelling and grammar

Author Response

Dear reviewer,

First of all, thank you very much for your valuable comments.

We have made changes based on your review of the manuscript.

Kind regards,

Yi Wang

Author Response File: Author Response.pdf

Reviewer 3 Report

This article deals with WC-10Ni+AgCuTi composite coatings and reports microstructure and hardness of samples fabricated at different brazing temperature. Authors explained in details influence of brazing temperature on coatings microstructure. They used simply research methods such as  microscopy observations, EDS and XRD analysis and finally hardness measurements.  The paper is written in a logical way and good in English. Moreover the obtained results may be useful for scientific community. Summarize, the manuscript is worth to publishing in Coatings journal but before few correction should be done:

Please notice that only hardness was measured – If you still want to use “Properties” in the article title other properties must be defined and presented. Please explain why the holding time was 30 min. The heating/cooling rate during brazing process should be given in Materials and Methods section. The methodology of Light Microscopy (Fig.2), XRD (Fig.6) and hardness (Fig.8) measurements must described in detail in Materials and Methods section. Do you use standards for EDS measurements? How was contain of carbon calculated? The scale bars must be more visible – Fig.1, Fig.4. Table 1 – please define the region for A and B points. Moreover the results of EDS measurements should be also presented in at%. The figures captions must be corrected (please use suitable term and definitions) e.g. - 1 – Particles of Ag68.8Cu26.7Ti4.5 powder (SEM), 8 – Linear hardness distributions…. etc. Fig.7 must be moved to Materials and Methods section. “Temperature”, “Microstructure” should be used in singular form – please check throughout the article.

Author Response

Dear reviewer,

First of all, thank you very much for your valuable comments.

We have made changes based on your review of the manuscript.

Kind regards,
Yi Wang

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors addressed most of the issues from the first review. However, the following minor issues should be addressed before publication:

- No reference to Fig. 2 is found in the text and should be added to the manuscript.

- I still highly recommend to change the colours in Fig. 7 (b, d, f, h) so that same elements have the same colour!

- Add details of Vikers testing to the manuscript (weight, how many tests to obtain mean values...)

- In conclusions: it should be 10^-3 Pa and not 10-3Pa

Author Response

Dear reviewer,

We have modified your review based on your comments, thank you again for your valuable comments!

Wish you a happy life!

Kind regards, Yi Wang

Author Response File: Author Response.pdf

Reviewer 3 Report

Dear Authors,

Please notice that some mandatory recommendations were omitted:

Fig.1, Fig.2a, Fig.6 - the scale bars must be more visible. Do you used standards for EDS measurements? How was content of carbon calculated? – these information must be given in Materials and Methods section. You must know that EDS is not suitable method for carbon content measuring. Table 1 – The results of EDS measurements should be ALSO presented in at%. Now these results are given in wt%! If you see point G the chemical composition of WC particle is properly for wt% (around 50 to 50 should be for at%).  Please put in the table 1 the at% result for each measuring point and correct the sentence “The energy spectrum analysis showed that the two solid solution components were Ag4.9Cu91.88 (% wt%) and Ag84.41Cu14.47 (at.% wt%), respectively, which were Cu-rich Cu-based solid solution and Ag-rich Ag-based solid solution.  (Lines 145-147) Fig.10 – The figure caption sounds strange. The caption must be clearly corresponding with the presented  dependence.

Author Response

Dear reviewer,

First of all, thank you very much for your valuable comments. We have carefully revised the draft based on your comments. The scale in all the pictures in the manuscript is clearly visible.

Kind regards,

Yi Wang

Author Response File: Author Response.pdf

Round 3

Reviewer 3 Report

Dear Authors,

Please notice that carbon contain for each point (indicated in Fig.6) must be presented in Table 1.

You must give in Materials and Methods section information about EDS measurement. Probably you use EDS standardless method with ZAF correction.

Moreover the caption of Table 1 must be updated. The EDS points are shown in Fig.6.

Author Response

Dear reviewer,

We appreciate your valuable comments. We will modify the manuscript as soon as possible based on your comments and upload it.

Wish you a happy life!

Best regards,

Yi Wang

Author Response File: Author Response.pdf