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Peer-Review Record

Investigation of Feedstock Preparation for Injection Molding of Oxide–Oxide Ceramic Composites

J. Manuf. Mater. Process. 2019, 3(1), 9; https://doi.org/10.3390/jmmp3010009
Reviewer 1: Grzegorz Matula
Reviewer 2: Anonymous
Reviewer 3: Anonymous
J. Manuf. Mater. Process. 2019, 3(1), 9; https://doi.org/10.3390/jmmp3010009
Received: 28 October 2018 / Revised: 7 December 2018 / Accepted: 20 December 2018 / Published: 16 January 2019

Round  1

Reviewer 1 Report

I congratulate you on a very interesting article. I look forward to further research results. I think it will be particularly interesting to see how the fibers behave during the injection. It is very probably that the fibers will be laid parallel to the flow direction, which will ultimately make that the properties of sintered composite are anisotropic

Author Response

Dear Reviewer,

Please open the attachment below for my answer for your comments.

Best regards

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript Investigated the feedstock preparation for hnjection 3 molding of alumina based ceramic composites. There are many interesting observations. However, there are still many ambiguous points and mistakes needed to be clarified and revised before acceptance. The comments are as below: 1. P.2: Figure 2 was used to demonstrate the reinforcement of oxide CMC. However, in this case the microstructure with dense alumina matrix with reinforced alumina fiber is desired rather than porous matrix. 2. P.3: The authors considered stearic acid as dispersant to inhibit the agglomeration. However, the addition of stearic acid decreased the mixing torque, but nearly did not affect the viscosity, suggesting the stearic acid may act as the internal lubricant. 3. P.4-6: I suggest the calculation of required stearic acid waste too page, which is meaningless. I suggest it can be removed and the addition of stearic acid can be calculated just based on BET value. 4. P.14: “In this work, PEG-based binding system shows lower viscosities than PW-based system probably because of better bonding between polar matrix of PEG/PVB and the solid particles, increasing fiber content lead to a decrease in viscosity. “ It is not consistent with the result of Table 5. 5. P.15: What is the difference between the two figures in Fig.13? 6. P.15: “the investigation for the effect of PVA sizing on the same images showed that, the fiber clusters or bundles were separated and relative homogeneously mixed with the binder.” No data was provided. 7. P.15: “the investigation for the effect of PVA sizing on the same images showed that, the fiber clusters or bundles were separated and relative homogeneously mixed with the binder.” I suggest it should be explained why? 8. P.16: “4. Discussion” should be corrected as Conclusion. 9. P.17: I cannot follow “The final mechanical characterizations can prove the critical importance of the fiber length.”, because no mechanical characterization was performed.

Author Response

Dear Reviewer,

Please open the attachment below for my answer for your comments.

Best regards

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper presents interesting results about development of CMC feedstock for injection molding. A lot of the description is oriented towards the calculation of «exact» amount of dispersant to be added to the feedstock based on the total surface to cover. Is it really necessary to do such calculations? What is the problem in adding an excess of dispersant? How are you sure that the dispersant covers «all» the surfaces of powder and fibers?

There are numerous details that should be clarified before publication. Here are some comments that should be answered to improve the overall quality of the paper to meet publication standards.

- Fig. 1: Do you have the authorization from ref 23 to use this figure?

- line 92: Give correct notation for chemical products.

- equation 3 and others: the symbols in the equations are not the same as those enumerated in the text. Example here: Wpi.

- line 183: For formal text, instead of «it's», use «it is».

- line 185: ... that is ...

- line 216: ...stearic acid and its effects ...

- Table 3: data for other surfactants are not useful.

- line 243: ... it was decided ...

- Table 4: I do not understand what is the meaning  of the values in the table. What is the unit for the different values? Gram? Gram/m2?

- line 245: ... equality of BET measurement over powder and fibers... What do you mean ?

- line 258: ... has a bimodal size distribution behavior...

- Fig. A1 and A2: The graphs are not of sufficient quality.

- line 267: ... even when they broke...

- Fig. 6: How did you evaluate the error bars on the graph?

- Everywhere, you use the words «surfactant» and «dispersant» to describe the same function. Please avoid confusion.

- Fig. A3: These graphs show the evolution of torque with time in different conditions. Since the torque scale is different from one graph to the other, it is difficult to see the effect of eliminating the sizing agent.

- lines 295-299: Could the increase in torque and kneading energy be related to the formation of agglomerates?

- Fig. 9: Is the difference between the two curves (on the graph to the right) significant? Error bars?

- line 322: model

- Fig. 10: What curve (red or green) corresponds to each data sets?

- line 355: What happens with PVA at 160°C? Does it transforms to «liquid phase» in the feedstock, then reducing the whole viscosity? Also you should consider that the amount of PVA increases continuously with the total fiber content.

- Fig. 13: the image on the right is useless.

- Your discussion at the end contains some elements of a conclusion...that is absent!

Author Response

Dear Reviewer,

Please open the attachment below for my answer for your comments.

Best regards

Author Response File: Author Response.pdf

Round  2

Reviewer 2 Report

The manuscript has been revised to meet the requirement of the comments. I suggest it can be accepted.

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