Thermally Sprayed Nickel-Based Repair Coatings for High-Pressure Turbine Blades: Controlling Void Formation during a Combined Brazing and Aluminizing Process
Round 1
Reviewer 1 Report
This work reports a study of thermally sprayed nickel alloy repair for turbine blades of Inconel 718.
The paper is interesting, attractive topic for investigation, but some requires and corrections must be taken into account before publication in Materials.
Introduction: This part of paper need attention because is only weak point of paper. Introduction must provide a comprehensive critical review of recent developments in a specific area or theme that is within the scope of the journal, not only a list of published studies or a bibliometric one. I personally feel that this part of paper is not concise enough from a reader's perspective.
Comments and questions:
- “This two-stage hybrid technology has both technical and economic adantages.” provide evidence.
- Device names are not required, like "Germany PVA Tepla, Wettenberg,”
- What was the surface roughness for different test parameters?
- Author wrote: “ Based on the appearance in the micrographs, these should be referred to as voids rather than as porosity” - please explain this phenomenon
Author Response
Dear Reviewer,
thank you very much for reviewing this manuscript for coatings and for your comments. The manuscript is revised according to the comments.
“This work reports a study of thermally sprayed nickel alloy repair for turbine blades of Inconel 718.
The paper is interesting, attractive topic for investigation, but some requires and corrections must be taken into account before publication in Materials.
Introduction: This part of paper need attention because is only weak point of paper. Introduction must provide a comprehensive critical review of recent developments in a specific area or theme that is within the scope of the journal, not only a list of published studies or a bibliometric one. I personally feel that this part of paper is not concise enough from a reader's perspective.”
- The introduction is rearranged, so that the reader gets more background information about repairing turbine blades (state of the art) and what was the idea of developing the hybrid technology to shorten the state of the art repair process.
“’This two-stage hybrid technology has both technical and economic advantages’. provide evidence.”
- It is now explained in the introduction and it was also addressed in the conclusions.
“Device names are not required, like Germany PVA Tepla, Wettenberg“
- It is revised now.
“What was the surface roughness for different test parameters?”
- The roughness is mentioned now.
“Author wrote: “Based on the appearance in the micrographs, these should be referred to as voids rather than as porosity” - please explain this phenomenon”
- An explanation is given now.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors studied the coating properties of a thermal spray turbine blade. The spraying method and experiment test are well described. However, there is a lack of analytical computation results by DOE technique. As the authors mentioned, they used the DOE. However it seems the results obtained by DOE are not clear. I think the authors should discuss more on the optimal/preferable spray conditions obtained by applying DOE.
Author Response
Dear Reviewer,
thank you very much for reviewing this manuscript for coatings and for your comments. The manuscript is revised according to the comments.
“The authors studied the coating properties of a thermal spray turbine blade. The spraying method and experiment test are well described. However, there is a lack of analytical computation results by DOE technique. As the authors mentioned, they used the DOE. However it seems the results obtained by DOE are not clear. I think the authors should discuss more on the optimal/preferable spray conditions obtained by applying DOE.”
- Of course it is right, that more calculations can be made. But in this case the DOE is just carried out to get a microstructure with the lowest porosity in the brazed joint. Strong fluctuations within the porosity, or the voids, have been found, so that a further evaluation of the DOE in terms of the main effects was not pursued. Furthermore, diffusion, segregation, solubility and precipitation processes cannot be covered by this DOE. But these facts are now mentioned additionally in the manuscript.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The paper can be accepted as it is.
