Microstructure and Phase Composition Changes in Polymer Fiber-Modified Thermacoat™ Lining Exposed to Contact with Liquid Steel

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The introduction provides a clear overview of the use of multicomponent clay and cenosphere linings in continuous steel casting. When introducing technical terms such as "ultimate flexural strength (UFS)" or "differential scanning calorimeter (DSC)," consider providing brief explanations for readers who may not be familiar with these terms. Emphasize the significance of the study. Why is it essential to understand the interaction between the modified Thermacoat™ lining and liquid steel?

Explain why polypropylene Belmix™ fibers were chosen for the modification. What specific properties do these fibers bring to the Thermacoat™ mixture?

The SEM images (Figure 3) illustrate the microstructure of the modified Thermacoat™ with polypropylene fibers. Discuss the observed changes in detail and their potential impact on the material's properties.

How does the transformation of the material, as observed in the TEM/BF images (Fig. 9), impact its properties under high-temperature conditions?

Discuss the limitations and uncertainties associated with replicating real working conditions in laboratory tests.

The summary effectively encapsulates the key findings. If available, consider incorporating any quantitative results or measurements from the experiment to strengthen the summary. Provide insights into the potential future implications of these findings, especially concerning practical applications and further research directions.

Author Response

• The introduction provides a clear overview of the use of multicomponent clay and cenosphere linings in continuous steel casting. When introducing technical terms such as "ultimate flexural strength (UFS)" or "differential scanning calorimeter (DSC)," consider providing brief explanations for readers who may not be familiar with these terms.
• Answer: A proper explanation was given in the text, e.g. in case of UFS: “The latter parameter gives stress at failure in bending, what is of most interest in case of that type of coatings and routinely applied in industry involved in production of such parts.” and in case of DSC: “The heating runs in differential scanning calorimeter (DSC) measuring the heat flow during continuous sample heating at 20 K/min showed that the endothermic effect of polymer fiber melting at ~165 ^oC was dominated by that from water evaporation without affecting the sample overall shape.”
• Emphasize the significance of the study. Why is it essential to understand the interaction between the modified Thermacoat™ lining and liquid steel?
• Answer: A proper explanation was given in the text, e.g. “In the worst scenario, a fast accumulation of combustion gases and lack of enough escape channels could lead to catastrophic removal of lining from the substrate”.
• Explain why polypropylene Belmix™ fibers were chosen for the modification. What specific properties do these fibers bring to the Thermacoat™ mixture?
• Answer: A proper explanation was given in the text, e.g. These fibers are easily accessible and low priced, what made them a material of choice as anti-shrinkage addition for bathroom concrete floors and alike.
• The SEM images (Figure 3) illustrate the microstructure of the modified Thermacoat™ with polypropylene fibers. Discuss the observed changes in detail and their potential impact on the material's properties.
• Answer: A proper explanation was given in the text, e.g.:” In case of these observation method, the brighter spots at the images were caused by irregular sharper points formed at the fiber ends cut by diamond saw. Simultaneously, it is of importance that practically no tangles were observed, as only such defects could have led to accumulation of larger amount of gases at one place during their combustion.”
• How does the transformation of the material, as observed in the TEM/BF images (Fig. 9), impact its properties under high-temperature conditions?
• Answer: A proper explanation was given in the text, e.g.: “Similar “needle-like“ microstructure was observed previously in heat treated calcium-magnesium-aluminium-silicate (CMAS) coating subjected to high temperature treatment (5h / 1250 ^oC), which authors tentatively (due to lack of TEM/ electron diffraction data) assigned as one of alumina forms [Y]. The matrix of their material was the first to liquefy during heating, what should take place also in the present case.”
• Discuss the limitations and uncertainties associated with replicating real working conditions in laboratory tests.
• Answer: A proper explanation was given in the text, e.g. “The laboratory-scale test covering placement of a drop of liquid steel over the Thermacoat™ modified with polypropylene fibers was only a kind of first approximation of working conditions in the vat filled with molten steel. The ceramic lances coated with such linings are used to blow oxygen into molten metal, what is connected not only with exposure to high temperature, but also to shear forces caused by disturbed flow of the liquid steel. However, the sacrificial role of the linings means that they would serve well the purpose as long as they avoid self-delamination within first second of such exposure. A problem in this case might be an explosive combustion of polypropylene fibers, e.g. reaction of such composite to high temperature. From that point of view placing even a small amount of a molten steel over Thermacoat™ substrate should gave a so much needed answer. And indeed, the experiment performed within this work  showed that most of the material remain in its original form, even as such exposure to temperature in excess of 1500 ^oC resulted in partial evaporation of some of its components leaving behind a heavily porous upper layer and HAZ below it.”
• The summary effectively encapsulates the key findings. If available, consider incorporating any quantitative results or measurements from the experiment to strengthen the summary. Provide insights into the potential future implications of these findings, especially concerning practical applications and further research directions.                                          Answer: A proper explanation was given: “Introduction of polypropylene fibers modified linings into the industry practice will have to be preceded with the real test by work, what is interfering with accepted still mill procedures and therefore generally opposed by industrial plants. Additionally, even a small rise in material costs are newer welcomed. However, a positive outcome of these experiment may not only bring a pay-back form lower number of factory rejects, but also cut-down on an amount of hard to recycle ceramic waste”.

Reviewer 2 Report

Comments and Suggestions for Authors

11) In general, the grammar used in this paper must be improved as it is difficult to comprehend the manuscript. I suggest that some of the professional English language authors, or an editor, take a more active role in the re-writing and editing of the manuscript.

22) Background information is insufficient and cited literature is limited.

33) Line 27: What does HT stand for?

44) Line 55: The unit of temperature used is inconsistent with others. The authors should stick to using either K or ℃ for temperature.

55) Line 70: Should be “strand” instead of “stand”

66) Line 85: Optical microscopy (OM) has previously been abbreviated in line 65.

77) Line 87: Transmission electron microscopy (TEM) has previously been abbreviated in line 65.

88) Line 155: What does BSE stand for?

99) Figure 8: 2 of the images are labeled incorrectly.

110) Line 259: Selected area (SA) was abbreviated for the first time here but it was already mentioned in line 90.

Comments on the Quality of English Language

The grammar used in this paper must be improved as it is difficult to comprehend the manuscript. I suggest that some of the professional English language authors, or an editor, take a more active role in the re-writing and editing of the manuscript.

Author Response

Comments and Suggestions for Authors

1) In general, the grammar used in this paper must be improved as it is difficult to comprehend the manuscript. I suggest that some of the professional English language authors, or an editor, take a more active role in the re-writing and editing of the manuscript. 

Answer: We followed the suggestion and corrected the manuscript as far as we were able to do it. 

2) Background information is insufficient and cited literature is limited. 

Answer: We supplied background information with more data including new citation from that area (sacrificial coatings).

3) Line 27: What does HT stand for?                                                                                                                             Answer: a proper information was inserted into the, e.g. “.., i.e. retained good high temperature (HT) properties of the non-modified material.

4) Line 55: The unit of temperature used is inconsistent with others. The authors should stick to using either K or ℃ for temperature.                                                                                                              Answer: The text was corrected as advised ( K was replaced with ℃).

5) Line 70: Should be “strand” instead of “stand”

Answer: The text was corrected as advised.

6) Line 85: Optical microscopy (OM) has previously been abbreviated in line 65.                                    

Answer: The text was corrected as advised.

7) Line 87: Transmission electron microscopy (TEM) has previously been abbreviated in line 65.            

Answer: The text was corrected as advised.

 

8) Line 155: What does BSE stand for? 

Answer: A proper explanation was inserted in to the text, e.g.

“Parts of the crucible subjected to direct contact with the liquid steel were section with a diamond saw and observed using OM with an Olympus KL as well as a ThermoFisher Scios II Dual Beam microscope enabling imaging both with secondary and back scattered electrons (SE/ BSE).”

9) Figure 8: 2 of the images are labeled incorrectly.

Answer: The images were corrected as advised.

10) Line 259: Selected area (SA) was abbreviated for the first time here but it was already mentioned in line 90.                                                                                                                              Answer: a proper corrections were made in the text.

Comments on the Quality of English Language: The grammar used in this paper must be improved as it is difficult to comprehend the manuscript. I suggest that some of the professional English language authors, or an editor, take a more active role in the re-writing and editing of the manuscript.

Answer: English language was checked and corrected.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

All of the comments have been responded to accordingly and the manuscript is now suitable for publication.