Use of Zr–Ti Alloy Melt Infiltration for Fabricating Carbon-Fiber-Reinforced Ultrahigh-Temperature Ceramic Matrix Composites
Round 1
Reviewer 1 Report
The paper " Use of Zr–Ti Alloy Melt Infiltration for Fabricating Carbon-Fiber-Reinforced Ultrahigh-Temperature Ceramic Matrix Composites" is devoted to the important topic; it is well-written and clearly organized. The paper is publishable after the minor revision.
Remarks: 1. It remains unclear, about Figure 6. EDX analysis should have specific values and units.
Remarks: 2. It is unclear about the preparation of Zr–Ti Alloys, such as mold and size?
Author Response
We appreciate for your review.
Answers for your comments are listed below:
Remarks: 1. It remains unclear, about Figure 6. EDX analysis should have specific values and units.
As reviewer suggested, the value of EDX analysis is shown in Fig. 6.
Remarks: 2. It is unclear about the preparation of Zr–Ti Alloys, such as mold and size?
As reviewer suggested, following sentences have been added and changed.
The sentences “Arc-melting was carried out in Ar atmosphere and ingots with the diameter of ~70mm and the thickness of ~10mm were obtained.” (p. 3 line 98-99.) has been added.
The sentence “Zr–Ti alloys with dimensions of 5 × 5 × 5 mm were set on the graphite plate.” has been changed to “Zr–Ti alloys with dimensions of 5 × 5 × 5 mm were cut from ingot and set on the graphite plate.”
Reviewer 2 Report
(1) In naming the samples, ZT12 is short for Ti-12at%Zr. This is misleading. I would suggest changing this to TZ12. The same for Ti-37at%Zr and Ti-80at%Zr.
(2) in page 4 line 114-115, since the porous carbon materials have continuous pore structures, how is the mdedial pore diameter defined? Please specify this.
(3) The last paragraph in Section 2.3 (line 130-140, page4) is about sample characterisation. I suggest to put this into a separate section 2.4
(4) For the measurement of contact angle, shouldn't this be conducted when the alloy is liquid? I understand that the metal is in Ar and direct measurment of the liquid alloy is tricky. Please comment on the potential difference between contact angle measuement at high temperature and room temperature. i.e. is the contact angle sensitive to temperature?
(5) Page 6, line 161. In Eqn. (1), the wetting angle is represnted by φ wherelse the contact angle is represented by θ. If they are the sme thing, please keep the symbol consistent.
(6) In page 6, line 173, the authors state that the infiltration terminated within a few secondes for all the alloys. How is this concluded. Please give more details on the infiltration experiment such as the infiltration time in the experimental section (section 2.3).
(7) For the EDX results, the C concentraiton is usualy not accurate. Special care must be taken in using the C content from EDX. Please give details on the SEM setting for the ED analysis to justify the results on C.
Author Response
We appreciate for your review. Answers for your comments are listed below:
(1) In naming the samples, ZT12 is short for Ti-12at%Zr. This is misleading. I would suggest changing this to TZ12. The same for Ti-37at%Zr and Ti-80at%Zr.
As reviewer suggested, ZT12, ZT37 and ZT80 have been changed to TZ12, TZ37, TZ80, respectively. (including Figs. 2, 3, 4, 6, 7 and 8)
(2) in page 4 line 114-115, since the porous carbon materials have continuous pore structures, how is the medial pore diameter defined? Please specify this.
The distribution of pore diameter for porous carbon is measured by mercury porosimeter and the median pore diameter is also calculated by the result in Ref. 32. However, the expression for the median pore diameter in the manuscript is unclear as reviewer pointed out. Thus, the sentence “The median pore diameter was ~3 μm” has been changed to “The median pore diameter was ~3 μm, which was measured by mercury porosimeter with the pressure of mercury by 0.024–414 MPa [32]”.
(3) The last paragraph in Section 2.3 (line 130-140, page4) is about sample characterization. I suggest to put this into a separate section 2.4
As reviewer suggested, the last paragraph in Section 2.3 has been separated as section 2.4. Thank you for pointing out.
(4) For the measurement of contact angle, shouldn't this be conducted when the alloy is liquid? I understand that the metal is in Ar and direct measurement of the liquid alloy is tricky. Please comment on the potential difference between contact angle measurement at high temperature and room temperature. i.e. is the contact angle sensitive to temperature?
The contact angle defined in the manuscript is not measured at liquid state. As reviewer pointed out, the contact angle is depending on temperature and exposure time. It should be measured during heat exposure. In the present study, we understand that the measurement of contact angle between liquid alloys and carbon is quite difficult. Thus, as a rough estimation for the apparent wettability, angle between solidified alloys and carbon is measured.
In connection with the above, the following words and sentences have been added and changed:
The words “contact angle” is inappropriate for the manuscript and changed to “apparent contact angle”.
The sentence “Since the angle is measured from melted alloys on graphite plate at room temperature, it defined as “apparent” contact angle.” has been added. (p. 5 line 151, 152.)
In abstract, the sentence “the apparent contact angle between Zr–Ti and C was ~20°–42° and that the alloys infiltrated into the preforms regardless of the Zr or Ti content.” has been change to “the apparent contact angle between Zr–Ti and C measured from melted alloys on carbon in room temperature was ~20°–42° and that the alloys infiltrated into the preforms regardless of the Zr or Ti content.” (p. 1 line 16-18)
(5) Page 6, line 161. In Eqn. (1), the wetting angle is represnted by φ wherelse the contact angle is represented by θ. If they are the same thing, please keep the symbol consistent.
“θ” is also used in diffraction angle for XRD analysis. The wetting angle is united by φ. Thank you for pointing out.
(6) In page 6, line 173, the authors state that the infiltration terminated within a few secondes for all the alloys. How is this concluded. Please give more details on the infiltration experiment such as the infiltration time in the experimental section (section 2.3).
The experimental infiltration heights for TZ12, TZ37, and TZ80 were 8.9±0.8, 14±3.5, and 11±1.6 mm, respectively. From the result of Washburn’s equation, the infiltration height by 8-18 mm is realized within few seconds. Then, the melting point of alloys are 1560-1700oC and it is considered that melted alloys are infiltrated into model preform immediately. As reviewer mentioned, the experimental procedure have been improved as “”.
(7) For the EDX results, the C concentraiton is usualy not accurate. Special care must be taken in using the C content from EDX. Please give details on the SEM setting for the ED analysis to justify the results on C.
As reviewer suggested, the C content detected by EDX is qualitative value. Thus, the sentence “(EDX, oxford Instruments, Aztec micsF+ x-stream-2, The U.K.)” has been added (p. 5 line 141, 142).
In addition, the words “Although the content of elements obtained by EDX is qualitative,” have been added (p. 7 line 191).
