Crack Driving Forces of Atmospheric Plasma-Sprayed Thermal Barrier Coatings

Round 1

Reviewer 1 Report

Dear Authors and Editors,

Here are my questions, comments and recommendations regarding the manuscript.

1) Line 82: What was the purpose of the selected time intervals 20, 50, 105, 225, 300, 350 hours?

2) Line 96, line 99, line 105, line 111, line 115, line 125, line 225, line 248, 306, 311, 321, 326, 368, 380, 45, 481, 483, 496, 500, 504, 516, 543, 553, 556 and many others contain problem with the reference citation:  Error! Reference source not found

3) Fig. 2a,  fig. 7 and fig. 10: does the data contain error bars or correspond to the sigle calculations?

4) The numeration of formula is misleading, there are many equations (1) and (2) in the text, so it is difficult to search for them. 

5) Fig. 5 caption does not contain detailed legend for a-d figures. 

6) Is it OK, that in fig. 8energy release rate is equal for 2,7 and 5 micrometers?

In general, I like the scientific style, the figures, however the article maybe too long but nt because of wordy style, but because of many aspects of the work discussed simultaneously. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

 

Dear Author:

In my viewpoint, the manuscript number coatings-1765072 titled "Crack Driving Forces of Atmospheric Plasma Sprayed-Thermal Barrier Coatings under Burner Cycling and Isothermal Furnace Cycling Testing Conditions" can be accepted to publication after major revision. This ranking is justified as follow.

My comments don't intend to lead to a delay in the manuscript publication but increases the publication velocity. See, as a whole, the manuscript sound much more as a technological peace. But, the manuscript should sound as a scientific one. I believe that at least three immediate actions are necessaries, as follow:

- A significant part of equations should be moved to one or more Supplementary files (two at least); in this clear identification of each term should be presented.

- Title needs be reorganized and/or re-write; as ist this title is very specific, furthermore. I suggest that words as model or modeling, thermal coating, crack formation and/or cracking propagation appears in the Title item. From my view point the manuscript is not based on methods of deposition. Then, the method of deposition should be only presented in the Abstract. Also, actual construction of manuscript provides one impression that model is valid only for this deposition method of coating. If true, such aspect should be mentioned.

- I would like suggest that author create the Experimental and methods item. This item can receive further data sample geometry etc...etc. assigned to reference 8.  Such approach can transform the present format of similar to a book chapter, or Thesis part in something close to a paper. Yet, in Figure 5 each plot can be shortened to reach all ones in a single page and inner vertical arrows should undergone one kind of re-engineering involving color and size, at moment brilliant blue is terrible to read. Yes, the old model should be described here. I suggest that strengths and weaknesses of classical model be inserted. In this sense, new model derived should be clearly presented in this proper position in the manuscript. What are parameters necessary to feed the new model?

Extra intervention:

- the drive force mentioned in the Title  is unclear along results and discusssion.

- the item Conclusion is too long. with half of size of the presented Conclusion item is sufficient. See, also, there are some inconsistences. Any item of scientific manuscript can contain opinion, free idea, suggestion, list of works to be maybe, etc...etc. Then, the part ..."Therefore, the cracking mode and failure mechanism for TBCs under real engine service conditions with longer high temperature holding times might be similar to isothermal furnace cycling tests. Still, the magnitude of the crack driving force is expected to be different, since a thermal gradient exists under the thermal cycling conditions for engine serving civil aircraft."… should be deleted since is an expression of possibility (therefore and might).

- At moment is unclear if most of plots are simple simulation, simulation/experimental plots or another. I suggest that legends supply such level of information. Also, see mention along manuscript the "thermal shock" that is an extreme condiction. Thus, the modeling reach a "thermal shock" phenomenon or not?

 

 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

 

Dear Author:

 

In my viewpoint, the manuscript number coatings 1765072    titled “Crack Driving Forces of Atmospheric Plasma Sprayed-Thermal Barrier Coatings under Burner Cycling and Isothermal Furnace Cycling Testing Conditions” can be accepted for publication after major revision.”

 

Overall comments:

In a broad sense, I have a firm position of reject manuscript similar to this due general misconception between book chapter and paper. However, I felt a great level of efforts by author part to submit a manuscript. In this sense, major faults in the design of manuscript is based on the in the no indicated experimental data and simulation via theoretical approach.

In fact, the abstract item manuscript should be modified to present such information.  Then, it is important to put clear to the reader if the manuscript is theoretical one. In this sense, the manuscript’s text and Figure legend should support information at about a theoretical plot or experimental one.

Taking in account Figures of item “Results and Discussion” there is a critical point that turn the reading of manuscript non fluent and discontinuous, that is also seen in the all legends assigned y-axis.  Seems that parameters physics doesn’t receive same names. Also, again, x-axis legends are incomplete. Really, I suggest that theoretical plots be only represented by continuous lines.  All Figures of “Results and Discussion” item, from Figure 7 up to Figure 20. See, as an example in Figure 14, the legend (“Thermal gradient energy release rate” is shortened with relation to the text of the manuscript, see “Equivalent thermal gradient ERR). From here, I suggest strongly that equation used be presented in Supplementary material, 13 files, parameters used should be listed, constants and parameters that equation were fed should be informed to the reader.

Now, thinking in the great number of Figures, it is important make an upgrade in the Reference Item. At moment, I think in a double of references, experimental and theoretical. I think that the form of load and isothermal preheating and further thermal cycling test. I suggest strongly that any acronym be used. Verify that all terms ascribed to the physical parameter be fully defined in the manuscript.  Furthermore, terms as “thermal gradient” should be defined in manuscript, as well as its physical origin.

At end, In the Conclusion item, I suggest strongly that part …”This might be another crack driving force after long-time service. The corresponding position for maximum CTE stress will shift downwards along the interface gradually as the TGO thickens. Therefore, the cracking mode and failure mechanism for TBCs under real engine service conditions with longer high temperature holding times might be similar to isothermal furnace cycling tests. Still, the magnitude of the crack driving force is expected to be different, since a the isothermal preheating and further thermal cycling thermal gradient exists under the thermal 818 cycling conditions for engine serving civil aircraft.” Be deleted of the text. Seems that seems or is closed to a suggestion. If not, insert this part in a previous part of manuscript

 

Title item:

 

I suggest a more short title. As example of Title, Crack Driving Forces of Atmospheric Plasma Sprayed-Thermal Barrier Coatings.

 

Author Response

[Coatings] Manuscript ID: coatings-1765072 -

 

Reviewer 2

*****************

Overall comments:

In a broad sense, I have a firm position of reject manuscript similar to this due general misconception between book chapter and paper. However, I felt a great level of efforts by author part to submit a manuscript. In this sense, major faults in the design of manuscript is based on the in the no indicated experimental data and simulation via theoretical approach.

 

R2 Question 1:

 

In fact, the abstract item manuscript should be modified to present such information.  Then, it is important to put clear to the reader if the manuscript is theoretical one. In this sense, the manuscript’s text and Figure legend should support information at about a theoretical plot or experimental one.

 

R2 Reply 1:

 

1). First of all, in the revised manuscript, we used all the time the “Track Changes” to modify the manuscript, so that any changes in the revised manuscript can be tracked via “point by point” approach.

 

2). In the revised manuscript, we addressed in the abstract, conclusion and also in the text that our work is on numerical and theorical modeling using the experimental data from the literature cited within the manuscript. We also modified all figure captions (legend) to reflect such changes in the revised manuscript. Also, all legend in y axis was modified to be consistent with description in the caption of each figure

 

R2 Question 2:

 

Taking in account Figures of item “Results and Discussion” there is a critical point that turn the reading of manuscript non fluent and discontinuous, that is also seen in the all legends assigned y-axis.  Seems that parameters physics doesn’t receive same names. Also, again, x-axis legends are incomplete. Really, I suggest that theoretical plots be only represented by continuous lines.  All Figures of “Results and Discussion” item, from Figure 7 up to Figure 20. See, as an example in Figure 14, the legend (“Thermal gradient energy release rate” is shortened with relation to the text of the manuscript, see “Equivalent thermal gradient ERR). From here, I suggest strongly that equation used be presented in Supplementary material, 13 files, parameters used should be listed, constants and parameters that equation were fed should be informed to the reader.

 

R2 Reply 2:

 

1). In the revised manuscript, we replotted almost all figures by following the role as reviewer suggested: theoretical and/or numerical results are plotted by continuous curves, while experimental and/or test results are plotted by dot points.

 

2). In the revised manuscript, following reviewer’s suggestion, we moved a lot of equations and their associated results such as figures, tables and references into the supplementary document. A section 2.1 was added in the supplementary document to make sure readers understand the derivation and application of parameters into energy functions.

 

3). In the revised manuscript, we added a list of nomenclature of all parameters and symbols used in the test to explicitly demonstrate the parameters used in the present study, so that the readers can understand what they indicate.

 

R2 Question 3:

 

Now, thinking in the great number of Figures, it is important make an upgrade in the Reference Item. At moment, I think in a double of references, experimental and theoretical. I think that the form of load and isothermal preheating and further thermal cycling test. I suggest strongly that any acronym be used. Verify that all terms ascribed to the physical parameter be fully defined in the manuscript.  Furthermore, terms as “thermal gradient” should be defined in manuscript, as well as its physical origin.

At end, In the Conclusion item, I suggest strongly that part …”This might be another crack driving force after long-time service. The corresponding position for maximum CTE stress will shift downwards along the interface gradually as the TGO thickens. Therefore, the cracking mode and failure mechanism for TBCs under real engine service conditions with longer high temperature holding times might be similar to isothermal furnace cycling tests. Still, the magnitude of the crack driving force is expected to be different, since a the isothermal preheating and further thermal cycling thermal gradient exists under the thermal 818 cycling conditions for engine serving civil aircraft.” Be deleted of the text. Seems that seems or is closed to a suggestion. If not, insert this part in a previous part of manuscript

 

R2 Reply 3:

 

1). “Thermal gradient” is defined and described in the Introduction section in the revised manuscript. In addition, a nomenclature was added in the revised manuscript, where any acronym was described for readers better understanding.   

 

2). In the conclusion of revised manuscript, we deleted the part as reviewer suggested.

 

 

R2 Question 4:

 

Title item:

I suggest a more short title. As example of Title, Crack Driving Forces of Atmospheric Plasma Sprayed-Thermal Barrier Coatings.

 

R2 Reply 4:

In the revised manuscript, the title was shortened as “Crack Driving Forces of Atmospheric Plasma Sprayed-Thermal Barrier Coatings”.