Study of the Evolution of the Residual Stresses in Thermal Barrier Coatings from Manufacturing to Its Operation Work

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

1.- First of all, the title of manuscript “Study of Residual Stress Evolution in Thermal Barrier Coating from its Manufacturing to the end of its useful life” is not suitable and needs to be rewrite as its scope is too broad needing more supports. The research efforts of this paper are more on the analysis of residual stresses of TBCs in two state of as-fabrication and after 1250 ℃ heat-treatment. There is no division of the TBCs application stage and no evolution of residual stresses with application time or temperature. According to the manuscript, the coating after heating at 1250 ℃ for 6 hours is still complete and has not failed or detachment, so it is hard to summarize “to the end of its useful life”.

You are right, the title is confusing. According to your recommendation, the following title is clearer. 

Study of the Evolution of the Residual Stresses in Thermal Barrier coatings from Manufacturing to its operation work.

 

2.- The grammar of this paper as well as the phrasing needs further improvement. There are several repetitions and incomplete statements in the text. For example, “In this project was determine the magnitude of the residual stresses …, from its manufacture to its operation work.” (Page 1, Abstract, the first sentence, Line 9); “during 6 hours of operation to evaluate the effect of coating deposition, operating temperature…” (Page 1, Abstract, Line 15); “this is low thermal conductivity, and low thermal expansion coefficient.” (Page 1, Line 33) and “The YSZ is the most… due to its thermal properties, low thermal conductivity, thermal shock resistance, and low coefficient of thermal expansion.” (Page 1, Line 35); “In addition to a corrosive and oxidizing atmosphere, which it may cause detachment of the ceramic layer.” (Page 2, Line 81) and so on. All in all, the manuscript needs to be thoroughly revised.

In this project was determine the magnitude of the residual stresses …, from its manufacture to its operation work.” (Page 1, Abstract, the first sentence, Line 9); “during 6 hours of operation to evaluate the effect of coating deposition, operating temperature…” (Page 1, Abstract, Line 15); It was corrected.

The YSZ is the most… due to its thermal properties, low thermal conductivity, thermal shock resistance, and low coefficient of thermal expansion.” (Page 1, Line 35). It was eliminated

In addition to a corrosive and oxidizing atmosphere, which it may cause detachment of the ceramic layer.” (Page 2, Line 81) It was eliminated

The grammar was checked, indeed there were some grammatical errors.

3. “There is no information in the literature regarding the stress generated at each stage from the manufacture of the TBC to its end of life time.” (Page 1, Line 19) This sentence is contradictory with the references that are cited in section of Results and Discussion to compare with results of this paper. E.g. “Values close to zero are observed, similar to those reported by et al. [3]” (Page 6, Line 226); “This behavior is similar to that reported by Lima et al. [26]” (Page 7, Line 235); “This results agrees with that observed by Khan et al. [23]” (Page 7, Line 247).

It is correct, (I already deleted this paragraph) if there is information on residual stresses in each stage, but it is in different articles separately. In this work, the residual stresses of each stage are shown. Residual stress profile (σT), which is the sum of the residual stresses caused by the deposition of the coating (σD), the stresses generated by the rapid cooling of the droplets sprayed by the plasma (Quenching Stress, σQ), residual stresses caused by the difference in coefficients of thermal expansion (Thermal Stress, σTH), stresses due to the operating temperature of gas tur-bines (σOT) and the stresses due to the CMAS infiltration in the TC (σCMAS)

 

4. A broad view of the whole manuscript reveals that this paper focus is on the analysis of residual stresses rather than on the preparation of TBCs, while the introduction part gives too much information about the TBCs preparation. The introduction should give more research progress about the analysis of residual stress using FEM. Especially, the method applied in this paper should highlight the recent research progress and the scope of application.

I added more information about FEM.

 

5. Lack of process details on the meshing of model. It should be given at the first model simulation. The MRCMRB procedure should also be given in detail.

In the meshing, Shell elements were used for the ceramic and metallic coatings, and Solid elements (hexahedral) for the substrate. 1,009 elements with 5,853 nodes were used for the substrate and 2,250 elements with 17,280 nodes for both coatings.

MRCMRB: I respect your comment,  let me tell you that the detail comes in the article referred to.

 

6. “This increase could also be attribute to the thickness of the TGO…” (Page 10, Line 304). It is necessary to decipher what the abbreviation TGO means at first time occurrence.

Modification made: thermally grown oxide

 

7. The pressure units should be unified. “Pressure (Bar)” (Table 1); “with a vacuum of 10-5 mmHg” (Page 4, Line 145).

Modification made:1.33×10^-8 bar

8. It is better to replace the phase “finite element simulation (FEM)” with “finite element method (FEM)” since the latter one is generally accepted.

Modification made:  finite element method

 

9. The reference are required in following sentence. “This result is similar to the result obtained experimentally, which reaches a maximum of 65 MPa (Fig.4).” (Page 9, Line 280).

The experimentation was carried out by us, we used the Modified Layer Removal Method for Duplex Coatings technique, we also validated with the FEM technique.

 

10. “In the TC, it can be observed that possibly the decrease in the concentration of zirconium is related to the increase in the profile of residual stress in compression.” (Page 9, Line 301). This sentence is a relatively important conclusive description for this paper, which explains the relationship of residual stress change with the TBCs composition. But, the correlation between the two actually is not evident from Figure 7. It can be seen from the picture that the overall change in zirconium and silicon content of TC does not appear to be significant, while the residual stress is notably reduced.

Your comment is correct, the wording was incorrect.

I modify it like this:

In the TC, it can be observed that possibly that the concentration of zirconium is related to the increase or decrease of the residual stresses. In Figure 7 it can be seen that the infiltration depth is also related to the residual stresses. The residual stress increases linearly when the zirconium is maintained at a similar concentration and the concentration depth increases, and between 260 µm and 300 µm depth there is a small decrease in zirconium which keeps the residual stress constant.

 

11. The use of abbreviations in manuscript is irregular and confusing, making it difficult to read.

I reviewed and modified.

Reviewer 2 Report

The Authors have done work on Study of Residual Stresses Evolution in Thermal Barrier Coating from its Manufacturing to the end of its useful life. Here are my recommendations:

1.   By the conclusions it says effect of microstructure on HC and erosion performance of TBC

2.  
I found most of the figures and text to be very mundane, well-known information more akin to a text book or thesis chapter than a journal article.

3.  
My OEM information is that CMAS is the primary issue for deposits and not traditional hot corrosion with S/Cl compounds.  Gd2Zr2O7 coatings and other non-YSZ coatings are most CMAS-resistant.  This does not come through paper.

4.  
SPS is not considered, there is no perspective that this is just a lower cost process to replace PVD but because of the limited standoff distance, it can't be used for large components so is mainly used aircraft engines.

5.   No mention of flash bond coatings which dominate current APS/HVOF/LPPS TBCs

 

6.  
In general, the paper is missing a critical assessment and without much insight or practical knowledge of TBCs.  

Comments for author File: Comments.pdf

Author Response

1. By the conclusions it says effect of microstructure on HC and erosion performance of TBC

These are my conclusions.

The residual stress profile of the TBCs, deposited by HVOF and APS, subjected to high tem-perature (1250°C) and CMAS attack for 6 hours, were obtained due to Quenching stress, Thermal Stress, the operating temperature of the gas turbines (1250°C); and CMAS infiltration in TC, us-ing the MRCMRB experimental technique, ANSYS software and the Noda equation, the follow-ing was concluded:

 

a) It was observed that the residual stresses caused by the deposition in the TC are al-most neutral because the magnitude of the residual stresses caused by the Quenching Stress and the magnitude of the compression stresses caused by Thermal Stress are very similar. The results are consistent with the literature. In BC, it was observed that the residual tensile stress resulting from the deposition process is that because the stress caused by the Quenching Stress is greater than the stress caused by the Thermal stress.  

b) It was observed that after the thermal treatment of the TBC at the operating tempera-ture (1250°C), compressive residual stresses were generated due to the relaxation of cooling re-sidual stresses. It can be observed that possibly that the concentration of zirconium is related to the increase or decrease of the residual stresses.

c) In this work, the magnitude of the residual stress profile of the TBC due to the rapid cooling of the drops sprayed by the plasma was determined (Quenching stress), due to the dif-ference in coefficient of thermal expansion between BC and TC (Thermal Stress), due to the oper-ating temperature of gas turbines (1250°C); and due to the infiltration of CMAS in the TC during 6 hours of operation.

d) The total maximum residual stress reached in the Top Coat was 139 MPa in compression and in the Bond Coat the maximum residual stress was 214 MPa in compression.

2.  I found most of the figures and text to be very mundane, wellknown information more akin to a text book or thesis chapter than a journal article.

Ansys  Figures were modify and TBC Figure.

3. My OEM information is that CMAS is the primary issue for deposits and not traditional hot corrosion with S/Cl compounds. Gd2Zr2O7 coatings and other non-YSZ coatings are most CMASresistant. This does not come through paper.

You are right, the job was to avoid the destruction of TBC-YSZ to determine its residual stress in the coating at each stage before its destruction. For that reason, Gd2Zr2O7 coatings were not considered.

4. SPS is not considered, there is no perspective that this is just a lower cost process to replace PVD but because of the limited standoff distance, it can't be used for large components so is mainly used for aircraft engines.

Thank you so much for your comments, We are using SPS in engines and small pieces.

The ceramic top layer is usually deposited by APS or Electron Beam Physical Vapor Deposition (EB-PVD) [23]. In this work, the ceramic layer was deposited by the APS process, since it is cheaper than EB-PVD [24-26], and has good tolerance to deformation due to microcracks and pores [26].

The metallic layer can be deposited by atmospheric plasma spray (APS), vacuum plasma spray (VPS), and HVOF. The VPS process represents the state of the art in metal layer deposition, however, the VPS chamber process requires evacuation, and flooding cycles are time-consuming, which limits the efficiency of the process, furthermore, the cost is relatively high due to vacuum operation [27]. In contrast, the HVOF spray process operates at atmospheric pressure and the investment costs are about one-tenth that of the VPS process. Therefore, the HVOF process is a good alternative for the deposition of bond coatings of the MCrAlY type [28].

[23] A. Cipitria, I.O. Golosnoy, and T.W. Clyne.  Sintering Kinetics of Plasma-Sprayed Zirconia TBCs. Journal of Thermal Spray Technology, Vol. 16, [2007] 809- 815.

 [24] R.A. Miller. Thermal Barrier Coatings for Aircraft Engines: History and Directions. Journal of Thermal Spray Technology.  Volume 6 (1997)  35-42

[25] A. Vaidya, V. Srinivasan, T. Streibl, M. Friis, W. Chi, S. Sampath. Process maps for plasma spraying of yttria-stabilized zirconia. An integrated approach to design, optimization, and reliability. Materials Science and Engineering A 497 (2008) 239–253

 [26] N. P. Padture, K. W. Schlichting, T. Bhatia, A. Ozturk, B. Ctegen, E. H. Jordan, M. Gell, S. Jiang, T. D. Xiao, P. R. Strutt, E. García, P. Iranzo and M. I. Osendi. Towards durable thermal barrier coatings with novel microstructures deposited by solution precursor plasma spray. Acta Mater. 49 (2001) 2251–2257

[27] A.S. Khanna, W.S. Rathod. Development of CoNiCrAlY oxidation resistant hard coatings using high velocity oxy fuel and cold spray techniques. Int. Journal of Refractory Metals and Hard Materials. 2014

[28] Metco, Sulzer. HVOF Solutions, Advanced Technology Solutions and Service. HVOF Solutions, Advanced Technology Solutions and  service: 2010.

 

 5.- No mention of flash bond coatings which dominate current APS/HVOF/LPPS TBCs

The purpose of this work was that the coating was not destroyed in order to obtain information on residual stresses with the different techniques used. The following investigation is to carry out an experimental design using a flash bond with different parameters. The answer to comment 2 is similar to this answer.

Thank you for your great contribution. 

In the article it is mentioned why not use flash bond coating

APS flash bond coatings deposited on a dense high velocity oxy-fuel (HVOF) bond coating have been shown to exhibit longer thermal barrier coating (TBC) lifetimes during 100 hour furnace cycle testing [42]. In this work, the heat treatment cycle was 6 hours, so flash bond coating was not used.

 

6.- In general, the paper is missing a critical assessment and without much insight or practical knowledge of TBCs.}

Modifications were made throughout the document, images and tex

Reviewer 3 Report

The paper seeks to introduce an approach “Study of Residual Stresses Evolution in Thermal Barrier Coating from its Manufacturing to the end of its useful life”. However, the authors should consider improving upon the quality to further highlight and emphasis.

 

1.    Based on the understanding of should be included in an abstract, add one or two lines highlighting what the problem you are trying to solve. I

 

2.    Consider changing the word “was” to “we” and put a comma after the word “project” in the first line of your abstract.

 

3.    The introduction needs to be improved by relating to the mechanics of the studied materials and their mechanical characteristics. The references to be included are: 10.1007/s10853-022-06994-3, 10.1177/0021998318790093, 10.3389/fmech.2020.00056, 10.1016/j.polymertesting.2017.09.009, 10.1016/j.msea.2020.140368, 10.1016/j.compstruct.2021.114698, 10.1007/s12540-022-01185-w, 10.1177/0731684417727143, 10.3390/met12020253 and 10.1002/app.46770.

 

4.    Write the unit of “10 mg/cm2” instead of “10 mg/cm2”. The number 2 is a power, not a multiplier.

 

5.    Start with a capital letter if you are introducing a new sentence. For instance, instead of “During”, you open the new sentence with “during” in the abstract.

 

6.    Consider adding one or two sentences highlighting the significance of the study.

 

7.    Tabulate all the physical and chemical properties of the materials used in this study.

 

8.    What is the size of the grit-blasted (in microns) used in cleaning the surface of the material and its significance?

 

9.     In the article, you made mention of your sample being cleaned in the open air, how did you protect your particle from external impurities after cleaning.

 

10.Rephrase the whole of this sentence “These TBCs were grouped in pairs to realize tests with a replica, during the heat treatment was subjected to a CMAS attack, CMAS was placed on the coated surface, with a concentration of approximately 10 mg/cm2”. It does make sense.

 

11. In the first line of your results and discussion, in this sentence “After the TC and BC deposition, the residual stresses for each layer (TC and BC) of the coating (TBC) results.” what are you trying to communicate?? It’s a broken sentence that has lost its main element of communication.

 

12. Most of your figures appeared so blurred. Check and re-insert them in a proper manner considering the visibility of all the text that comes with it.

 

 

13. Separate the variables and their corresponding units in your conclusion with a space like you have done in all the sections.

Author Response

1. Based on the understanding of should be included in an abstract, add one or two lines highlighting what the problem you are trying to solve.

 I add the lines that appear in red.

 The deposition, quenching stress, thermal stress operation temperature and infiltration.

The total maximum residual stresses reached in the YSZ was 139 MPa in compression and in the CoNiCrAlY the maximum residual stress was 214 MPa in compression.

 

2. Consider changing the word “was” to “we” and put a comma after the word “project” in the first line of your abstract.

I modified the sentence.

Residual stresses magnitude generated by the deposition, quenching stress, thermal stress, operation temperature and infiltration were determine in the thermal barrier coating (TBC) of gas turbines 

 

3. The introduction needs to be improved by relating to the mechanics of the studied materials and their mechanical characteristics. The references to be included are: 10.1007/s10853-022-06994-3, 10.1177/0021998318790093, 10.3389/fmech.2020.00056, 10.1016/j.polymertesting.2017.09.009, 10.1016/j.msea.2020.140368, https://doi.org/10.1016/j.compstruct.2021.114698, 10.1007/s12540-022-01185-w, 10.1177/0731684417727143, 10.3390/met12020253 and 10.1002/app.46770.

 Check all the proposed items, only 2 are related to the type of work done. These were cited.

14. Pape , T. Coors and G. Poll. Studies on the influence of residual stresses on the fatigue life of rolling bearings in dependence on the production processes. Front. Mech. Eng.  (2020) 6 1-9. https://doi:10.3389/fmech.2020.00056

 

31. Ahmad, B.; Zhang, X.; Guo, H.; Fitzpatrick, M.E.; Neto, L.M.S.C.; Williams, S. Influence of Depositio. Strategies on Residual Stress in Wire+ Arc Additive Manufactured Titanium Ti-6Al-4V. (2022), 12 1-20. https://doi.org/10.3390/met12020253

 

4. Write the unit of “10 mg/cm2” instead of “10 mg/cm2”. The number 2 is a power, not a multiplier.

I modified the unit.

10 mg/cm²

 

5. Start with a capital letter if you are introducing a new sentence. For instance, instead of “During”, you open the new sentence with “during” in the abstract.

I modified the sentence.

The TBCs were heat treated at 1250 °C, with CMAS (CaO, MgO, Al₂O₃ and SiO₂) attack by concentration of 10 mg/cm² for 6 hours in order to evaluate the evolution of the state of residual stresses in the coating at high temperature

6. Consider adding one or two sentences highlighting the significance of the study.

 Throughout the document there were significant changes, they are in red.

 

7. Tabulate all the physical and chemical properties of the materials used in this study.

Ok, they were already tabulated.

 

8. What is the size of the grit-blasted (in microns) used in cleaning the surface of the material and its significance?

The size of grit-blasted is 1.1 mm (1100 microns), and G20 alumina was used. Yes, it has significance but pressure, time, and distance are involved. 

 

9. In the article, you made mention of your sample being cleaned in the open air, how did you protect your particle from external impurities after cleaning.

 Before starting the deposition, the samples are cleaned with acetone and air in a closed chamber.

 

10. Rephrase the whole of this sentence “These TBCs were grouped in pairs to realize tests with a replica, during the heat treatment was subjected to a CMAS attack, CMAS was placed on the coated surface, with a concentration of approximately 10 mg/cm2”. It does make sense.

After depositing the TBC on the stainless steel substrate AISI 304, the thermal treatment of the TBCs was realized in a tubular furnace SWGL-1600x, at a temperature of 1250 ° C with CMAS attack of 10 mg/cm² on TBC surface. 

11. In the first line of your results and discussion, in this sentence “After the TC and BC deposition, the residual stresses for each layer (TC and BC) of the coating (TBC) results.” what are you trying to communicate?? It’s a broken sentence that has lost its main element of communication.

The text was corrected.

 In the Figure 3, it can be seen the residual stresses caused by deposition of the coating (σD), b) quenching stress (σQ), and c) thermal stress (σTH) [23].

 

12. Most of your figures appeared so blurred. Check and re-insert them in a proper manner considering the visibility of all the text that comes with it.

You are correct.

I modify and corrected some Figures. (TBC Figures and ANSYS Figures)

 

13. Separate the variables and their corresponding units in your conclusion with a space like you have done in all the sections.

The modification is already done.

Round 2

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

1. The first sentence of ABSTRACT has an obviously grammatical error and needs further revision.

The sentence was modify:

Residual stresses magnitude generated by deposition, quenching stress, thermal stress operation temperature and infiltration in the thermal barrier coating (TBC) of gas turbines was determined.

 

2. According to the description of TBCs in INTRODUCTION, it is easy to understand the coating structure. Figure 1 is best placed in the second section (2.1 TBC deposition).

 

Figure 1 was moved to section 2.1 TBC deposition.

 

3. The format of Al2O3 in Table 2 need to correct. This manuscript can be published in “COATINGS” journal after the author revise abovementioned issues.

Format was modify:

          Al₂O₃

Reviewer 2 Report

The paper can be accepted in its current form.

Author Response

Figure 1 was moved to section 2.1 TBC deposition.

 

 

Reviewer 3 Report

The introduction wasn't yet improved to include the given references. Authors declared that they added two references of the suggested list but these two added references weren't part of the suggested list.

Kindly add these new references on coating technologies in the introduction:  10.1016/j.jiec.2022.06.023, 10.1007/s10853-022-06994-3 and 10.1016/j.porgcoat.2022.107015.

Author Response

Kindly add these new references on coating technologies in the introduction:  10.1016/j.jiec.2022.06.023, 10.1007/s10853-022-06994-3 and 10.1016/j.porgcoat.2022.107015.

I added new references.

The electrophoretic deposition (EPD) process of polyaniline (PANI) technique allows a better control in the deposition of the coating [ 24, 25], which can avoid or reduce its porosities and increase its protection against corrosion [26].

 

[24] M. Fuseini, and M. M. Y. Zaghloul. Statistical and qualitative analyses of the kinetic models using electrophoretic deposition of polyaniline. (2022) . J. Ind. Eng. Chem. https://doi.org/10.1016/j.jiec.2022.06.023

[25] M. Fuseini, and M. M. Y. Zaghloul. Qualitative and statistical approaches of the electrophoretic deposition kinetics of polyaniline copper coating. Prog. Org. Coat. (2022) 171. https://doi.org/10.1016/j.porgcoat.2022.107015.

[26] M. Fuseini, M. M. Y. Zaghloul., M.F. Elkady and A. H El-Shazly. Evaluation of synthesized polyaniline nanofibres as corrosion protection film coating on copper substrate by electrophoretic deposition. J. Mater. Sci. (2022) 57 6085–6101. https://doi.org/10.1007/s10853-022-06994-3

 

Round 3

Reviewer 3 Report

The authors have successfully made the corrections. The paper can be accepted and published.