Manufacturing and Performance of Carbon Short Fiber Reinforced Composite Using Various Aluminum Matrix

Round 1

Reviewer 1 Report

The manuscript presents interesting research on the fabrication and testing of carbon fiber reinforced Al alloys. The results are well organized, however, some mandatory revisions are required before it can be considered for acceptance.

1. The abbreviation “CSF” is used before the definition.
2. The X-rag diffraction spectra results given in Fig. 5 can only reflect the type of chemical bonds in the fabricated material, however, the bonding condition between the short carbon fibers and their surrounding Al matrix is unclear. It is suggested to add EDS results at the boundary of the carbon fibers for an in-depth analysis.
3. As the carbon fibers are distributed in the Al matrix, how can the Vickers hardness reflect the hardness of the composites? The authors are requested to show the hardness indentations and discuss whether the measured hardness can reflect the local hardness or global hardness of the fabricated composite materials.
4. In addition to the ultimate tensile strength, the yield strength and elongation are also important mechanical properties that should be compared and discussed in section 3.3.
5. According to the Introduction and Conclusion sections, the novelty of this work is the development of a new fabrication process without preform manufacturing for CSF/Al. I strongly suggest the authors compare the mechanical properties of the composites fabricated in this research with those fabricated with preform manufacturing. This would add considerable value to the current work.

Author Response

We have modified the manuscript accordingly, and detailed corrections are listed below point by point:

Reviewers’ Comments:

Reviewer #1:

The manuscript presents interesting research on the fabrication and testing of carbon fiber reinforced Al alloys. The results are well organized, however, some mandatory revisions are required before it can be considered for acceptance.

1. The abbreviation “CSF” is used before the definition.
Response:

Thank you for your useful comment. We modified that the carbon short fiber (CSF) is used before the definition.

2. The X-rag diffraction spectra results given in Fig. 5 can only reflect the type of chemical bonds in the fabricated material, however, the bonding condition between the short carbon fibers and their surrounding Al matrix is unclear. It is suggested to add EDS results at the boundary of the carbon fibers for an in-depth analysis.

Response:

Thank you for this comment. We added analysis data by EMPA and EDS around the carbon fiber.

3. As the carbon fibers are distributed in the Al matrix, how can the Vickers hardness reflect the hardness of the composites? The authors are requested to show the hardness indentations and discuss whether the measured hardness can reflect the local hardness or global hardness of the fabricated composite materials.

Response:

The measurement of hardness is global hardness of the composite material, and a photograph of indentation and description are added to prove the hardness values.

4. In addition to the ultimate tensile strength, the yield strength and elongation are also important mechanical properties that should be compared and discussed in section 3.3.

Response:

Thank you for your useful comment. We added and discuss of elastic modulus, yield strength and elongation of each composites.

5. According to the Introduction and Conclusion sections, the novelty of this work is the development of a new fabrication process without preform manufacturing for CSF/Al. I strongly suggest the authors compare the mechanical properties of the composites fabricated in this research with those fabricated with preform manufacturing. This would add considerable value to the current work.

Response:

Thank you for this comment. We agree with this suggestion. The properties of all composites were compared with the composites fabricated the preform (SiO₂ binder). And I also modified the graph.

Reviewer 2 Report

In the present research, the authors try to investigate the thermal and mechanical properties of carbon short fiber reinforced Al based composites. The authors exhibit some results but there are some questions in the present state.

1. The authors titled the paper as “Thermal and mechanical properties of carbon short fiber reinforced Al and Al alloy based composites”. However, the authors have present more microstructure and phase analysis. The title could not reflect the content and the authors are suggested to revise the title.
2. In the content, the author describe the carbon short fiber by the CSF. However, they us the CFs to abbreviate the words of carbon fibers. Without the full explanation of CSF, the appearance of CSF is really so confusing. The authors are suggested to add the abbreviation of the CSF, when it appears firstly.
3. In the experimental, the authors use the low pressure infiltration to fabricate the composite. It wonders how to control the process to obtain the well distributed the CSF in the composite. The authors should explain it int he experimental in detailed. Moreover, the authors should provide the macrostructure of the composites to demonstrate the state of the CSF in whole as-fabricated composite.
4. In the experimental, there are several descriptions are similar. These descriptions could be unified and make the experimental clearly.
5. In content, the authors give the morphology of the Ni plated carbon fibers. It wonders why the authors have not provided the SEM image with heat treatment? That would be more helpful to understand the surface state of the carbon fibers after recrystallization.  
6. In the content, the authors described that the higher pressure of 0.8MPa lead to an increase of volume fraction of Ni plated CSF in composite. Such a description is so confusing. Firstly, there is only 0.8 MPa has been applied during the fabrication of the composite, and then how to obtain the opinion of the higher pressure? Moreover, the increased volume fraction of Ni plated CSF is also confusing? How could the volume fraction of CSF increase? That should be described in the experimental.
7. In the Fig.4, what is the meaning of defects? The authors should explain it in detail.
8. What is the elongation of the composites? Without the ductility of the composite, how to evaluate the failure of the composite?
9. In the content, the authors should give the cross-sectional microstructure adjacent to the fracture, which could help to understand the role of the CSF during the failure of the composites.
10. There are some grammar errors and repeated sentences. The authors are suggested to check the manuscript carefully and revised the errors.

Author Response

We have modified the manuscript accordingly, and detailed corrections are listed below point by point:

Reviewers’ Comments:

Reviewer #2:

1. The authors titled the paper as “Thermal and mechanical properties of carbon short fiber reinforced Al and Al alloy based composites”. However, the authors have present more microstructure and phase analysis. The title could not reflect the content and the authors are suggested to revise the title.

Response:

Thank you for your useful comment. We have modified the title. “Manufacturing and performance of carbon short fiber reinforced composite using various aluminum matrix”. And we added phase analysis data by EMPA and EDS around the carbon fiber.

2. In the content, the author describe the carbon short fiber by the CSF. However, they us the CFs to abbreviate the words of carbon fibers. Without the full explanation of CSF, the appearance of CSF is really so confusing. The authors are suggested to add the abbreviation of the CSF, when it appears firstly.

Response:

Thank you for this comment. We modified that the carbon short fiber (CSF) is used before the definition.

3. In the experimental, the authors use the low pressure infiltration to fabricate the composite. It wonders how to control the process to obtain the well distributed the CSF in the composite. The authors should explain it int the experimental in detailed. Moreover, the authors should provide the macrostructure of the composites to demonstrate the state of the CSF in whole as-fabricated composite.

Response:

Thank you for this comment. We have included a new figure and explanation of the fabrication process of composites.

4. In the experiment, there are several descriptions that are similar. These descriptions could be unified and make the experimental clearly.

Response:

Thank you for your useful comment. Duplicate serial descriptions were deleted and modified.

5. In content, the authors give the morphology of the Ni plated carbon fibers. It wonders why the authors have not provided the SEM image with heat treatment? That would be more helpful to understand the surface state of the carbon fibers after recrystallization.  

Response:
Thank you for your useful comment. As the reviewer says, I think it is more accurate to express the surface condition of the heat-treated carbon fiber in SEM. The reference paper shows that the trend observed in the heat-treated Ni-plated carbon fiber is similar to the plating state. So we didn't observe the SEM of the plated fibers. I will make sure to observe SEM and add it to the next paper to be submitted.

6. In the content, the authors described that the higher pressure of 0.8MPa lead to an increase of volume fraction of Ni plated CSF in composite. Such a description is so confusing. Firstly, there is only 0.8 MPa has been applied during the fabrication of the composite, and then how to obtain the opinion of the higher pressure? Moreover, the increased volume fraction of Ni plated CSF is also confusing? How could the volume fraction of CSF increase? That should be described in the experimental.

Response:

Thank you for your useful comment. We revised the inaccurate explanation. As you say, there is no difference in pressure in the same amount of nickel plated coated fiber, but pores are affected when using different matrices at the same pressure. In the next paper, we will organize the data on the relationship between the pressure and volume ratio of fibers.

7. In the Fig.4, what is the meaning of defects? The authors should explain it in detail.

Response:

Defect means pore. The defect of the manuscript was modified to pores.

8. What is the elongation of the composites? Without the ductility of the composite, how to evaluate the failure of the composite?

Response:

Thank you for your useful comment. We added and discuss of elastic modulus, yield strength, and elongation of each composite.

9. In the content, the authors should give the cross-sectional microstructure adjacent to the fracture, which could help to understand the role of the CSF during the failure of the composites.

Response:

Thank you for your useful comment. The comment in the review is correct. In this manuscript, only the microstructure on the surface of composites is included, but the microstructure on the cross-section is almost identical to the microstructure on the surface of composites. So I only expressed the surface section of composites.  I added information on this one in the manuscript.

10. There are some grammar errors and repeated sentences. The authors are suggested to check the manuscript carefully and revised the errors.

Response:
Thank you for your useful comment. I checked the manuscript carefully and revised it.

Reviewer 3 Report

This paper investigates the effect of alloying elements on the mechanical and thermal properties of CF/Al matrix composites. It is of interest to the technical community. This paper can be accepted after several minor revisions.

1. The title of this paper should be revised. The current title “Thermal and mechanical properties of carbon short fiber reinforced Al and Al alloy based composites” reads too general.
2. The English expression of the Abstract should be polished.
3. It is suggested to add a figure to show the fabrication process of CF/Al composites.
4. 2: The caption of Fig.2 is inconsistent with the figure. For example, in the caption, Fig.2(b) is “Ni plated CSF (60s)”. But in Fig.2(b), it says “Plating time 90s”.
5. 3d, 3e, and 3f are missing.

Author Response

We have modified the manuscript accordingly, and detailed corrections are listed below point by point:

This paper investigates the effect of alloying elements on the mechanical and thermal properties of CF/Al matrix composites. It is of interest to the technical community. This paper can be accepted after several minor revisions.

1. The title of this paper should be revised. The current title “Thermal and mechanical properties of carbon short fiber reinforced Al and Al alloy based composites” reads too general.

Response:

Thank you for your useful comment. We have modified the title. “Manufacturing and performance of carbon short fiber reinforced composite using various aluminum matrix”

2. The English expression of the Abstract should be polished.

Response:

Thank you for your detailed consideration of the abstract. We have modified the abstract.

3. It is suggested to add a figure to show the fabrication process of CF/Al composites.

Response:
We have included a new figure of the fabrication process of composites.

4. The caption of Fig.2 is inconsistent with the figure. For example, in the caption, Fig.2(b) is “Ni plated CSF (60s)”. But in Fig.2(b), it says “Plating time 90s”.

Response:

Thank you for your useful comment. The caption of Fig.2 is corrected.

5. 3d, 3e, and 3f are missing.

Response:

Thank you for your useful comment. I deleted 3d, 3e, and 3f.

Round 2

Reviewer 1 Report

All my concerns are addressed. 

Reviewer 2 Report

In the present state, the authors have revised the paper and answered the questions. Now, the paper is improved and could be acceepted.