Investigation of Breakaway Time Delay Phenomenon in Isothermal Test with Zircaloy-4 under Oxygen Atmosphere at 1000 °C

Round 1

Reviewer 1 Report

An interesting work that studies the oxidation behavior of zircaloy-4 under controlled oxidative atmosphere. The manuscript is well organized. The experimental part is clear and the conclusions are supported by the results. My only concern is that the aim is not clear and in the current it appears as a listing of experimental results without any specific aim. In my opinion, it can be considered for potential publication after the following comments are addressed:
1) In the introduction section, the purpose of this work has to be better described. What is the aim? Why do we do this process and why do we want to study it? Which application is referred to? What is the ultimate goal? Do we want to raise temperature and be oxidized and how much? Target values? Some additional more up to date references of the last decade would also be appreciated. 
2) Why did you choose 1000 oC? Please explain in the manuscript.

Author Response

1) In the introduction section, the purpose of this work has to be better described. What is the aim? Why do we do this process and why do we want to study it? Which application is referred to? What is the ultimate goal? Do we want to raise temperature and be oxidized and how much? Target values? Some additional more up to date references of the last decade would also be appreciated. 

Introduction was modified according to your opinions.

2) Why did you choose 1000 oC? Please explain in the manuscript.

It also specified in modified introduction. 

Reason of selecting the temperature is because breakaway phenomenon is dramatically changed around this temperature. 

Author Response File: Author Response.pdf

Reviewer 2 Report

This manuscript investigated the breakaway time delay phenomenon in the Zircalay-4 under an oxygen atmosphere through isothermal tests. The authors also discuss the role of temperature on the thickness of the oxide layer and its effect on the zirconium oxidation behavior and the breakaway time. I suggest the authors must thoroughly revise the manuscript even before it is published in the Applied Sciences journal. I suggest a major revision of the manuscript. A lot of grammatical errors in the whole manuscript. Science is not well communicated to the reader at all.

1. Pg1, L35: “were a good in agreement with” it should be “were in good agreement with”
2. Pg2, L50: “paper” “work”
3. Pg2, L80: Please state the reason behind the choice of oxygen to argon ratio 2:1.
4. Figure 2-4: The font size of the X and Y axis labels is very small. Please make it clear and proportionate.
5. Pg3, L113: “These results were interpreted in point of view reaction heat.” Such sentences make no sense at all. It should rather be “These results were interpreted with respect to the reaction rate or in context to the reaction rate”
6. Pg3, L114: itothermal must be changed to isothermal
7. Figure 3a: what does n= 1, 2, 3 mean and why is not mentioned in the text??
8. Pg4, L140: Grammatically incorrect sentence, please correct it.
9. Pg5, L152: It should be the reason for breakaway time.
10. Pg5, L156: It should be “the peak temperature increases with the increase in the oxygen flow rate due to rise in the oxygen flow rate per outer surface of the metal as shown in the figure 4b”.
11. Pg6, L166: Correct the sentence to “as reported earlier in the literature 1,4,7 at temperatures above 1050C dense columnar oxides were favorably formed.”
12. Pg6, L173: Use taken or captured instead of prepared.
13. Pg6, L173: 2 hours isothermal tests must be changed to 2 hours of isothermal test
14. Pg6, L187: Previously reported TG mass gain.
15. Pg7, L199: It should be reported in the literature instead of detected by the other researchers
16. Pg7, L205: Grammatically incorrect sentence, please correct it.
17. Pg8, L223: Mass gain rate is also contributed to the must be changed to “mass gain rate also contributes to”
18. Pg8, L233: “columnar oxide is assumed that it equals to the thickness” must be changed to “columnar oxide is assumed to be equal to the thickness”
19. Pg9, L240: what is tetragonal stabilization.
20. The conclusion section needs more evidence to be substantiated.
21. Need to stress more on the role of the tetragonal and monoclinic phases leading to breakaway.

Author Response

Thanks you for your comments.

I revised my paper according to your comments, especially grammar problems.

And I received 'English Editing check' in MDPI.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The author's response is convincing. In my humble opinion the manuscript can be published in the present form. 

Author Response

Thank you for your kind comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

Inconsistency with the figures is not resolved at all. Figure 2, X and Y axis labels reading from 1 to 1000, -1.0 to 1.0 are so small you can barely see them. The same comments hold good for Figures 3 and 4 as well, the axis font is further reduced in these figures. Please have the same font size for all the figures. Authors need to make the figures legible to the reader and must be consistent. Please tale time to plot the figures properly.  

Author Response

Thank you for your very important comments.

Your comments are definitely right. These are good lessons for me. Thanks again.

I modified Figures.  Font size of labels and axis values of all Figures are 30 and 26, respectively.

Thank you so much.

Author Response File: Author Response.pdf