Enhancing the Photoluminescence and Microstructural Transformations of Al₂O₃/Glass–Ceramic Composite Coatings by Laser Irradiation

Round 1

Reviewer 1 Report

In my opinion the article is interesting and worth to be published. I think that the obtained results are clearly presented, and their interpretation is reasonable. The conclusions are well supported by the experimental results. I recommend the acceptance of this article for publication in the present form.

Author Response

  Dear reviewer, thank you very much for your comments on the article.

Reviewer 2 Report

This work is on the spectroscopic properties of the composite coating based on Al2O3/glass-ceramics deposited on the brass substrate. Superficial layer is modified by CO2 laser at different irradiation which caused phase transformation and crystallization process is studied.

 

The results presented in the manuscript  I believe would be interesting for the readers. Before continuing, I suggest to the Authors to consider the following revisions, which I feel should be addressed and clarified:

1. Conclusion: It seems to me that the Authors are listing the results.
2. In the Introduction part, in my opinion, there should be more about the objective of the present investigation and connection with the literature data. Please provide Up-to-date literature.
3. Experimental: Please provide more details about methods use. For example, XRD.
4. Figure 6. Place legend with all phases present in sample. Gamma Al2O3 is identified base on only one diffraction line?
5. Figure 7. Intense Diffraction line at around 30 degrees 2 theta is not identified.
6. Could you maybe perform Scherrer analysis to get information about the crystallite size of identified phases?
7. Please edit the English language and style and check spelling.
8. I would like to see reviewed manuscript.

 

 

Author Response

Dear reviewer, thank you very much for your contributions and comments on the article. Below is a list of reviews performed:

1. Changes were made to the wording of the conclusions. 
2. The introduction was revised and improved to be more related to the objective of the research. An article from the year 2021 was included.
   
   
3. The crystalline structure of the sample was investigated by an
   X-ray diffraction (XRD).  Gamma Al2O3 is effectively identified based on a single diffraction line, which is found for as-deposited alumina by plasma spray.  Intense diffraction line around 30 degrees 2 theta is not identified in figure 7 because only Alumina peaks are being present in this figure. This analysis of intense diffraction at 30 degrees is presented in Figure 6.
4. Scherrer analysis was not performed for this study but is planned to be used for a later publication which we are already working on.

Reviewer 3 Report

The introduction do not enough focus on the application of this specific SiO2-ZrO2 / Al2O3 coating and the target properties.

In materials and methods.

Please indicates how the surface of the brass substrate is prepared (state of surface, roughness, cleaning).

Information on the thicknesses of the Al2O3 and ZrO2-SiO2 coating must be given.

I do not understand different brass substrates (line 85). Only one kind of substrate has been used, I seems to me?

In results and discussion.

Figure 3 shows an SEM image and not optical image as it is said in line 113. A comparison we an image before laser treatment wold be nice (better than 2 different magnifications).

Figure 4 is not easy to read. Elemental composition of spots 1 and 2 could be given

Figure 5b, interpretation of the image is poor (lines 126 – 128).

Figure 6 must be completed by the XRD pattern of the substrate and also with the pattern of the coating before the annealing at 850°C.

Figure 7, please identifiy on the figure the different phases better than the (hkl)

Clearly, this paper must be completed by a characterisation of some properties of the coating (roughness, hardness,…) to demonstate potential use.

Author Response

Dear reviewer, thank you very much for your contributions and comments on the article. Below is a list of reviews performed:

1. The introduction was complemented with information about the SiO2-ZrO2 / Al2O3 system, which is not well known. We regret not finding much literature on the matter but it is part of our motivation to study this system.
2. The method of preparing the substrates was clarified in the methodology.
3. Although not exactly measured in this system, the thickness of the alumina coating with similar manufacturing parameters is between 500 and 600 microns. It is a study that we are currently carrying out. Unfortunately, an exact measurement was not made in this system because the SEM cross-sectional image using the glass-ceramic was impossible to obtain because the cut of the sample further fractured the coating. 

1. Line 85 (now 95) was corrected, it is a single substrate.
2. Line 113 (now 124) was corrected, it is a SEM image.
3. The title of figure 4 was changed where it is explained that in 4a (SEM image) there are the two positions 1 and 2. Then in 4a the EDS analysis of position 1 is presented and in 4b, the analysis of position 2 is presented.
4. Information on image 5b was supplemented.
5. Regarding the X-ray study of the substrate, it is something that we would like to achieve, despite the fact that they are found in the literature, but unfortunately the diffraction equipment with which the experiments were carried out is under repair and this result has not been achieved.  We have tried in other laboratories but due to a pandemic it has not been possible, we regret not being able to include this spectrum.
6. Figure 7 was modified according to the indications. The tetragonal phase of zirconia was included, as it was a suggestion from another evaluator. 
7. It is true, it can be supplemented with information on mechanical properties of the material and roughness. It is not easy to achieve this with the fragile contribution of the glass-ceramic, but we are currently reviewing nanoindentation tests. We have some results but they are too preliminary to include in this publication. Anyway, we greatly appreciate the suggestion.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Dear Authors,
I can see the improvement of the submitted manuscript. However, I am not sure it is sufficient at this stage based on all reviews.

Author Response

Dear evaluator, once again I appreciate your comments, as they have allowed us to improve the document. We have included changes in the introduction in order to arrive at an application as you have suggested. We hope you like these changes, as far as our application is concerned, it has been very favorable to visualize the context of this application and the potential of the results obtained. Thank you very much.

Author Response File: Author Response.docx

Reviewer 3 Report

Line 143-144 : About the thickness, a reference must be added

Author Response

Dear evaluator, thank you very much for reviewing the document again and the suggestions made.

As for the reference that you suggest, it is difficult to take it from the literature, since the equipment where we carry out this procedure is an industrial equipment and they do not usually report this information in scientific articles, but rather they are dedicated to coating industrial parts. In this sense, I would like to propose to complement this paragraph with the SEM image of this material deposited on another substrate (Inconel 718 alloy) which is also our result. If this is possible, I greatly appreciate the opportunity of publication, leaving as my main experience greater attention in the determination of this parameter for all the proposed coatings.