Numerical Study on Chemical Vapor Deposition of Aluminide Coatings

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Title of the paper: Numerical Study on Chemical Vapor Deposition of Aluminide Coatings.

Comments:

• The authors should elaborate on the limitations of the work in the introduction.
• Figure 7(a) and Figure 7(b) should be explained with relevant references.
• In Figure 8, the reaction rate is low at both lower and higher temperatures. The authors need to support their claims with relevant references.
• Conclusion should be concise.
• The authors should spell-check the manuscript thoroughly to eliminate grammatical errors.
• Many of the references are much older.

Comments on the Quality of English Language

The authors should spell-check the manuscript thoroughly to eliminate grammatical errors.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Report on manuscript coatings-3804736

Title: “Numerical Study on Chemical Vapor Deposition of Aluminide Coatings”

By Shihong Xin et al.

In the manuscript, the authors report on theoretical studies of predicting flow field within a Chemical Vapor Deposition (CVD) reactors and on the influences of deposition processes on the chemical reaction rates occurring at sample surfaces. The authors employ computational fluid dynamics (CFD) to gain the goal of the research. This study allows predicting optimization of a CVD reactor design and deposition parameters. The results presented here may be of interest for potential readers of the journal “Coatings”. However, the revision of the manuscript should be made as reported just below:

• Page 2: In the sentence “Aluminide coatings, are widely applied to turbine blades due to their simple preparation process, low cost, and mature technology” the term “mature technology” should be explained.
• The authors several times explain the meaning of the acronym CVD (chemical vapor deposition). What reason for?
• The authors have developed three models for CVD aluminide coating preparation system and established that one of them (Model A) suites well in such a case. What about application if this model to other SVD coating preparation systems? Are there some temperature range limitations in such a model for real coating preparation systems? 1253 K? Other temperatures?
• The authors conclude that the use of Model A will allow “forming a uniform aluminide coating on the structural surface.” Are there any experimental confirmations of this statement for CVD aluminide or other coating preparation systems?
• Figures 7, 8 and 11are of poor quality and should be revised.
• What about uncertainties of the data presented in Figs. 7, 8 and 11?
• It is interesting to know about consistence of these theoretical data with those existing in literature for related coating systems employed in similar experimental conditions.
• What about implication/suggestion of the present study in future?
• The authors should check misprints and grammar/syntax errors occurring throughout the text.

Comments on the Quality of English Language

The authors should check misprints and grammar/syntax errors occurring throughout the text.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The introduction outlines the general concept of CVD coating technology and its relevance, but it lacks depth in reviewing recent advancements and key challenges in aluminide coating processes. Some references are cited, but a broader review of recent work—especially comparative studies on reactor design, deposition rates, or flow modeling—would strengthen the background. Including more context about gaps this research addresses would further justify the study's originality. The introduction presents a coherent context for the study, referencing key challenges in CVD-based aluminide coating technologies. It also includes 22 references, covering both recent and foundational works.

The use of CFD simulations for analyzing gas flow, temperature, and pressure effects in a CVD reactor is appropriate and well-justified for a non-invasive, parametric study. The research design uses CFD simulations to systematically evaluate the effects of reactor structure, inlet velocity, temperature, and pressure. This approach is appropriate for studying flow fields and deposition dynamics in CVD processes. The step-by-step simulation setup and comparison of structural types demonstrate a sound methodology for achieving the study's objectives.

While the general approach is understandable, more detailed explanation of the CFD modeling setup, boundary conditions, mesh density, and solver configurations would enhance reproducibility. While the core simulation parameters and models are mentioned, some key methodological details are either missing or too briefly described. For instance, the specifics of the boundary conditions, turbulence model (if applicable), convergence criteria, and grid independence testing are not fully elaborated. A more detailed description would enhance reproducibility.

The results are structured logically, with clear discussion of velocity, pressure, and temperature effects. Each section links findings with physical interpretations. The results are logically organized and follow the research design. Trends related to velocity, temperature, and pressure are clearly reported, with concise observations. However, in some cases, additional quantitative comparisons or visual aids (e.g., contour plots of velocity fields or reaction rates) could help readers better grasp the findings.

The conclusions directly stem from simulation outputs and analysis. Recommendations regarding optimal velocity and temperature are consistent with the results presented. The conclusions are directly drawn from the simulation results. The selection of Type A as the optimal structure, the identification of the optimal inlet velocity (0.065 m/s), and the observation of temperature and pressure trends are all consistent with the findings. The acknowledgment of flow nonuniformity and areas for future optimization adds credibility. 

While generally clear, some figures could benefit from enhanced resolution, labeled axes, and brief captions clarifying their role in supporting key findings. The figures are informative, but some of them lack detailed captions, units, or labeled axes, which can hinder clarity. Enhancing resolution and ensuring all labels are legible would improve the presentation quality. Annotating key findings directly on figures (e.g., optimal values) could also improve reader engagement.

Some sentences in the manuscript are overly long or contain awkward phrasing (e.g., passive constructions and unclear transitions).

The use of CFD to optimize a CVD reactor for aluminide coatings on complex surfaces presents an innovative application not widely addressed.

The topic is relevant to aerospace, energy, and materials engineering, but the impact is limited by the lack of experimental validation or case studies.

Structurally sound, but some figures, English language, and methods description could be clearer.

The references are generally appropriate, covering key foundational topics such as CFD, CVD reactor design, and coating processes. However, integrating a few more recent or high-impact references—especially experimental or CFD studies on similar reactor systems—would strengthen the contextual grounding.

Comments on the Quality of English Language

The manuscript demonstrates technical competence but would benefit from thorough editing for clarity and grammar. Some sentences are overly long, and certain technical terms are used inconsistently. Improving sentence structure and ensuring consistent terminology will significantly enhance readability.

Author Response

Please see the attachment

Author Response File: Author Response.pdf