Experimental Design of the Adhesion between a PEI/Glass Fiber Composite and the AA1100 Aluminum Alloy with Oxide Coating Produced via Plasma Electrolytic Oxidation (PEO)

Round 1

Reviewer 1 Report

Please see enclosed text.

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 1:

Dear Reviewer 1, we appreciate your valuable corrections to our manuscript.

• The acronym PEI should be defined. 

Dear reviewer, the acronym "PEI" had its meaning added to the manuscript

• What is AA1100 alloy? Al99Cu ? What does mean AA?

Dear reviewer, the acronym "AA" stands for aluminum alloy, and the same was added to the manuscript

• Line 85 : Is it possible to know the weight %? Would it be possible to know the average size of the 
  fibers (and their diameter) ?

Dear editor, in previous studies, the diameter of composite material glass fiber is about 0.006 mm

• Yes, aluminum, due to its characteristics, naturally forms an oxide layer (passivation); however, the anodization process has the tendency to enhance this layer while simultaneously reducing the growth time.

• Line 189 Table caption. What do mean or stand for Model, Sum of Square, Mean square, F value and Prob> F. Does 0.7994 = 0.8? If yes change all the data accordingly. Add the units in the first column if needed. What do mean Time² , Voltage² , (Time.Voltage does not mean Time x Voltage since 0.38 x 2.94 = 1.1172), an so on… The caption of the table should let the reader understand the table without reading the manuscript...

Time. Voltage does not represent multiplication, but rather how well these parameters together can capture the variability of the process. The other items can be found in various manuscripts cited in this work, but the ANOVA (analysis of variance) was used more to assess how much each process parameter influences the final outcome.

Dear reviewer, some of your notes can be seen directly in the manuscript, especially marked with red text for better viewing

Reviewer 2 Report

The article aims to review the state-of-the-art of fused deposition modelling for polymer composites. However, several big issues must be well addressed before acceptance for publication. The reviewer’s comments are as follows:

(1)      What is the biggest contribution of this review? Because several similar publications can be found currently. The reviewer cannot see the significance of this study which must be well presented.

(2)      This study is not strictly related to optimisation, and it is suggested to modify the title into “Experimental design of the adhesion between PEI/Glass fiber composite and AA1100 aluminum with oxide coating produced by  Plasma Electrolytic Oxidation (PEO)”.

(3)      What is the unit for LSS in Table 2?

(4)      As mentioned by the authors, “It is notable that among the parameters of the PEO process, there are other factors that can be investigated in future studies, such as electrolyte temperature, distance between electrodes (GAP), substrate chemical composition, and the use of additives to improve electrolyte conductivity, such as Potassium Hydroxide (KOH)”, why not consider these aspects? Is it because of the limitations using Central Composite Design? It is recommended that the authors can discuss more on other DOE or optimisation methods.

Fine

Author Response

(1)      What is the biggest contribution of this review? Because several similar publications can be found currently. The reviewer cannot see the significance of this study which must be well presented.

Although there are some publications on the bonding of materials with dissimilar physical properties, such as the bonding of aluminum with a polymeric composite, this study brings innovation by exploring the application of thermoplastic composite. This material enables recycling and employs a low-cost bonding technique. However, the main innovation of this study lies in the application of plasma electrolytic oxidation to enhance the adhesion between materials, with PEO being a more environmentally efficient process.

(2)      This study is not strictly related to optimisation, and it is suggested to modify the title into “Experimental design of the adhesion between PEI/Glass fiber composite and AA1100 aluminum with oxide coating produced by  Plasma Electrolytic Oxidation (PEO)"

Dear reviewer, the title of the manuscript has been revised.

(3)      What is the unit for LSS in Table 2?

in MPa

(4)      As mentioned by the authors, “It is notable that among the parameters of the PEO process, there are other factors that can be investigated in future studies, such as electrolyte temperature, distance between electrodes (GAP), substrate chemical composition, and the use of additives to improve electrolyte conductivity, such as Potassium Hydroxide (KOH)”, why not consider these aspects? Is it because of the limitations using Central Composite Design? It is recommended that the authors can discuss more on other DOE or optimisation methods.

Given the number of parameters to be used, computational analysis would require a more sophisticated computer to process all the data. However, the premise of this study was to analyze only three parameters due to the limitation in the quantity of available samples.

Reviewer 3 Report

In this work the authors treated an aluminum alloy with Plasma Electrolytic Oxidation in order to form a coating of Al₂O₃. The treated alloy was then joined with a thermoplastic composite (PEI +glass fiber). They used a 2³ factorial design to in order to study the effect of some of the parameters which are involved in the PEO process, on the shear strength of the joined samples. These parameters were the immersion time, the applied Voltage and the electrolyte concentration.

The factorial design is typically used for process optimization. Since the model was not statistically significant no optimization could be performed. There is a reasonable amount of experimental work. The results are clearly presented and adequately discussed. The conclusions are supported by the results.

However, I cannot recommend this manuscript for publication as “communication”. A “communication” article its not just an article of short length. A communication is supposed to present some highly innovative and urgent results. The results of this study are not such. Thus, I suggest rejection. If the authors submit the work as regular article, then I would suggest minor revision according to the comments below.

1.     The authors should clearly mention the concept for this work. For example, did the authors perform PEO in order to improve the adhesion of the PEI composite on the Al alloy?

2.     Explain PEI in the abstract.

3.   Section 2.3 Since the design is 2³ why there are 5 levels for each variable in Table 1?                                                                                                               

Minor Editing is required. see for example:

Rewrite the following sentence in the abstract. The meaning is difficult to follow. “Through variance analysis, it was determined that the statistical model encompasses approximately 80% of the variability in the adhesion process between materials.”

 Line 77. Replace “including” with “namely”

         Lines 253-255. “This….liquid aluminum”. This sentence needs to be rewritten.

Author Response

   1.  The authors should clearly mention the concept for this work. For example, did the authors perform PEO in order to improve the adhesion of the PEI composite on the Al alloy?

In this study, the adopted strategy was to generate a thin layer of aluminum oxide on the alloy through the process of plasma electrolytic oxidation, aiming to enhance adhesion with the thermoplastic polyetherimide matrix in the composite. This was achieved by creating micro-pores, which contribute to improving mechanical anchoring.

2.     Explain PEI in the abstract.

PEI is short for Polyetherimide, an engineering polymer belonging to the thermoplastics family. It is widely used in sectors such as aerospace, automotive, and electronics due to its excellent physical properties, particularly when reinforced with meshes, such as fiberglass and/or carbon fibers.

3.   Section 2.3 Since the design is 2³ why there are 5 levels for each variable in Table 1?   

With the intention of developing a Central Composite Design (CCD) factorial planning with 5 levels, the aim is to create a response surface for the statistical model. However, due to the model's significance falling below 95%, it was not possible to create an optimized system. Consequently, the manuscript title has been modified.

Round 2

Reviewer 2 Report

The authors have not fully revised the manuscript.

none

Author Response

Dear Reviewer,

I sincerely appreciate your time and effort dedicated to reviewing this work. Your contributions are invaluable in improving its quality and relevance to the academic community.

I would like to inform you that all recent change requests have been addressed according to your suggestions. Regarding one of the reviewers' comments about the possibility of transforming this work into a full article, I would like to share my perspective on this matter. I believe that initially, this work was conceived as a communication due to the current volume of available data. To be considered a full article, a significant addition of data and analysis would be necessary.

However, I am open to dialogue and the possibility of expanding this work into a full article format in the future, should there be access to additional data that could substantially enrich the content and analysis presented.

Once again, I appreciate the valuable feedback and the opportunity to enhance this work.

Sincerely, Rafael R. Lucas

Reviewer 3 Report

The authors responded to my comments. However I see that it has been submitted as communication. It should be published as regular article

Author Response

Dear Reviewer,

I sincerely appreciate your time and effort dedicated to reviewing this work. Your contributions are invaluable in improving its quality and relevance to the academic community.

I would like to inform you that all recent change requests have been addressed according to your suggestions. Regarding one of the reviewers' comments about the possibility of transforming this work into a full article, I would like to share my perspective on this matter. I believe that initially, this work was conceived as a communication due to the current volume of available data. To be considered a full article, a significant addition of data and analysis would be necessary.

However, I am open to dialogue and the possibility of expanding this work into a full article format in the future, should there be access to additional data that could substantially enrich the content and analysis presented.

Once again, I appreciate the valuable feedback and the opportunity to enhance this work.

Sincerely, Rafael R. Lucas