Structural, Mechanical, and Tribological Characterization of Magnetic Pulse Compacted Fe–Cu Bimetallic Particles Produced by Electric Explosion of Dissimilar Metal Wires
, Anton Khrustalyov 1,2, Andrey Filippov 1, Yuri Mironov 1, Aleksander Lozhkomoev 1, Marat Lerner 1 and Sergei Tarasov 1,*Round 1
Reviewer 1 Report
The manuscript reports structural, mechanical and tribological characterization of Fe-Cu bimetallic particles produced by Electric Explosion and then compacted by Magnetic Pulse Technique. Microstructure of the powder and as-compacted samples are investigated. Mechanical strength and tribological properties are also investigated for the as-compacted samples. The study is well performed and gives nice details about Fe-Cu materials obtained by magnetic pulse. The manuscript is prepared at a high scientific-methodical level but needs some minor revision. The minor comments are given as follows:
(Materials and Methods: Then it was degassed at 350C…) Were the parameters of magnetic compaction process selected according to author’s research or literature reports? If parameters are selected from literature please add references.
(Compacted sample characterization: …samples had the density…). Which method was used to estimate density of as-compacted samples?
(Mechanical strength) Information about mechanical strength should be added to Experimental part (i.e. devices, sample dimensions, ...)
(Mechanical strength: The microhardness was…) Information about microhardness test should be also added to Experimental part .i.e. load. How many samples were measured? How many tests were performed per one sample?
Author Response
Reviewer 1
The manuscript reports structural, mechanical and tribological characterization of Fe-Cu bimetallic particles produced by Electric Explosion and then compacted by Magnetic Pulse Technique. Microstructure of the powder and as-compacted samples are investigated. Mechanical strength and tribological properties are also investigated for the as-compacted samples. The study is well performed and gives nice details about Fe-Cu materials obtained by magnetic pulse. The manuscript is prepared at a high scientific-methodical level but needs some minor revision. The minor comments are given as follows:
(Materials and Methods: Then it was degassed at 350C…) Were the parameters of magnetic compaction process selected according to author’s research or literature reports? If parameters are selected from literature please add references.
A: When doing the literature search we could not find any data on the MPC of the bimetallic Fe-Cu powders. Therefore, magnetic pulse compaction parameters were selected experimentally by tailoring them to provide the acceptable level of the consolidated sample strength. A corresponding phrase has been added to the text, see lines 130-133.
(Compacted sample characterization: …samples had the density…). Which method was used to estimate density of as-compacted samples?
A: The sample’s density numbers were obtained using the hydrostatic weighing.
(Mechanical strength) Information about mechanical strength should be added to Experimental part (i.e. devices, sample dimensions, ...)
(Mechanical strength: The microhardness was…) Information about microhardness test should be also added to Experimental part .i.e. load. How many samples were measured? How many tests were performed per one sample?
A: All available information about equipment and samples was added. Lines 138-143
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this paper bimetallic Fe-Cu nanoparticles produced using the electric explosion of two immiscible metal wires and consolidated into disks using magnetic pulse compaction have been characterized for phase composition, mechanical and wear properties
In the introduction section, the authors have portrayed a good background to the use of Al-Cu bimetals, their corrosion, mechanical and tribological properties and the different methods they are synthesized, including from bi-metallic powder form. However, the technique used in the current study "electric explosion of wires" has not been discussed in the introduction, and the abbreviation EEW has been used within the text without referring to what it stands for.
The authors should describe the powder sample preparation procedure for TEM and whether the sample is indeed representative of the synthesized material. From the SEM image in Figure 3, it is clear, and the authors have mentioned this, that there are much larger particles present in the mix. This makes the particle size distribution given un Figure 2b irrelevant.
Moreover, the EDS line profile should be done on a larger number of particles in TEM, especially the more electron transparent ones. For example, for the one shown in Figure 2c, there is a chance that the large particle selected is pure Fe with some smaller particles on the surface. I am not convinced that all particles are indeed Fe-Cu type. An EDS elemental map would be ideal.
The justification given in the conclusion section for MPC as a suitable compacting method for the EEW particles is vague and has to be rewritten.
The manuscript is written poorly in terms of choice of words and English grammar in some parts, especially in the discussion section. There are also other minor issues with this study, all of which are pointed out throughout the manuscript and can be found in the attached pdf document.
In general, this paper presents a new synthesis route to obtain bimetallic Fe-Cu nano-particles. However, the article lacks in providing a complete picture of the size distribution of these particles. The TEM work used for particle size distribution is invalid as it fails to sample larger particles. The article also suffers from poor English vocabulary and grammar in some of the sections. Finally, the article is weak in bringing out the novelty of the work using a strong scientific language. The article might be reconsidered after considerable and thorough revisions.
Author Response
Reviewer 2
In this paper bimetallic Fe-Cu nanoparticles produced using the electric explosion of two immiscible metal wires and consolidated into disks using magnetic pulse compaction have been characterized for phase composition, mechanical and wear properties
In the introduction section, the authors have portrayed a good background to the use of Al-Cu bimetals, their corrosion, mechanical and tribological properties and the different methods they are synthesized, including from bi-metallic powder form. However, the technique used in the current study "electric explosion of wires" has not been discussed in the introduction, and the abbreviation EEW has been used within the text without referring to what it stands for.
A: The text was added to the Introduction section (lines 60-64)to read: “A EEW phenomenon is observed when a 5-15 length and 0.1-0.5 mm diameter conducting wire is energized by an electric current with pulse duration 0.5-5.0 ms and density as high as 106÷109 A/cm2 is thus causing its atomization. Such a process is used to obtain metallic nanoparticles of metals and alloys in either Ar or He atmosphere at 105 …5×105 Pa. The explosion product expansion velocity the buffer gas is at the level of 103 m/s [11]. “
Also Figure 1 was added which shows the EEW electric circuit diagram
The text was added to the Section 2 Material and methods (lines 89-92) to read: “A capacitor battery (C ) is charged from the direct current power source (PS) until reaching U0 voltage level. On reaching the Uo, the air-gap discharger is activated and the circuit is energized by a current pulse of 107 A/cm2 density. The wires suffer burst atomization into fine drops.”
The authors should describe the powder sample preparation procedure for TEM and whether the sample is indeed representative of the synthesized material.
A: Samples for TEM were prepared by dispersing 50 mg powder in 100 ml alcohol and sonication for 5 min in order to provide the powder deagglomeration. Then 10 microliter portion of the resulting suspension was placed on a carbon-coated 3 mm diam. gold mesh substrate and dried. The text was added (lines 110-113)
From the SEM image in Figure 3, it is clear, and the authors have mentioned this, that there are much larger particles present in the mix. This makes the particle size distribution given un Figure 2b irrelevant.
A: Figure 3 was replaced for a new version with particle size distribution accounting for the micron-sized large particles. Lines 116-123, the text was added to read:” The particle size distribution was reproduced using the data obtained from sedimentation in a disk centrifuge DC24000 (CPS Instrument Inc. USA). The resulting sonicated for 5 min suspension contained 20 mg particles dispersed in 10 ml alcohol. The duration of analysis was 30 min. The particle size distributions were obtained by counting not less 4,386× 109 isolated particles.
The mean particle size (as) was determined from measuring the BET specific surface area in a Sorbtometr-M (Katacon, Russia) instrument and formula
1, where r is the density ~8 g/cm3; S is the specific surface area, m2/g” .
Fig.3b shows that the number of the micron-sized particles is negligible.
Furthermore, we carried out up to five independent experiments on measuring the BET specific surface area and compared the mean surface area particle size to that of obtained from TEM.
The text was added to the paper (lines 167-169) to read: “The mean by five measurement BET specific surface area of the powder was 9.1±0.9 m2/g so that according to formula 1 mean particle size was as=82±9 nm. This value is close to that of obtained from TEM analysis’.
Nevertheless, we agree with the reviewer’s comment that the particle size distribution obtained from TEM was incorrect.
Moreover, the EDS line profile should be done on a larger number of particles in TEM, especially the more electron transparent ones. For example, for the one shown in Figure 2c, there is a chance that the large particle selected is pure Fe with some smaller particles on the surface. I am not convinced that all particles are indeed Fe-Cu type. An EDS elemental map would be ideal.
A: The EDS maps were added to the revised version of the manuscript instead of profiles (Fig 3d). Unfortunately, dwell time needed for identification of each particle was limited because of the particle drift in the TEM view field. Therefore , we could not be able to provide better space resolution.
AlsoThe EDS maps have been also obtained and even published with paper by Marat I. Lerner, Sergey G. Psakhie, Aleksandr S. Lozhkomoev, Aliya F. Sharipova, Alexander V. Pervikov, Irena Gotman, and Elazar Y. Gutmanas. Fe–Cu Nanocomposites by High Pressure Consolidation of Powders prepared by Electric Explosion of Wires. Adv. Eng. Mater. 2018, 1701024. DOI: 10.1002/adem.201701024.
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Figure 3 (former Figure 2). TEM images of the bimetallic EEW Fe-Cu particles (a, c), particle size distribution (b), (d) the EDS map of the particles present by Figure 3c. |
The justification given in the conclusion section for MPC as a suitable compacting method for the EEW particles is vague and has to be rewritten.
A: This section has been rewritten
The manuscript is written poorly in terms of choice of words and English grammar in some parts, especially in the discussion section.
There are also other minor issues with this study, all of which are pointed out throughout the manuscript and can be found in the attached pdf document.
A: We did our best to revise the text and make it more readable
Figures 10a,b (former Figures 9a,b) were replaced with their new versions
In general, this paper presents a new synthesis route to obtain bimetallic Fe-Cu nano-particles. However, the article lacks in providing a complete picture of the size distribution of these particles. The TEM work used for particle size distribution is invalid as it fails to sample larger particles.
A: Their number is too low to seriously change the mean particle size. Also we replaced Figure 3 for more realistic one which includes the micron-sized particles too. One may see that their number is negligible. Also it is easy to remove them from the powder.
The article also suffers from poor English vocabulary and grammar in some of the sections. Finally, the article is weak in bringing out the novelty of the work using a strong scientific language.
The article might be reconsidered after considerable and thorough revisions.
A: The authors did their best to improve the wording in accordance to the reviewer’s comments
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors have significantly improved the manuscript in terms of clarity, written English and added new data to improve the soundness of the research work.
There are still some minor errors within the text some of which are pointed out in the attached documents.
After these minor revisions, the article seems suitable for publication.
Comments for author File: Comments.pdf
Author Response
Dear Sir!
Please, find below our a list of revisions made to the text according to your comments.
Lines 62-63. the power exponent transformed into a superscipt
Lines 68-69, a comma inserted to read:" ....for obtaining a composite, it is reasonable...."
Line 137. A sentence "Mechanical tets for compression...." was changed to read "Mechanical tests for compression..."
Figure 3, a legend was added to the EDS particle map
There was two Figures 6 and Figure 7 was missing. One of figures 6 was renamed into Figure 7
Figure 10. Symbols a and b were inserted in Fig10a and Fig 10b, respectively
Lines 311-312. A sentence "The EEW Fe-Cu bimetallic nanoparticles are structurally consist of two immiscible metals 311 bonded into a singular particle." was changed to read:"The EEW Fe-Cu bimetallic nanoparticles structurally consist of two immiscible metals bonded into a singular particle".
Line 312. A sentence "That means that the real powder dispersity becomes even higher s compared to that of mono-metallic ones.." was changed to read : "That means that the real powder dispersity becomes even higher as compared to that of mono-metallic ones."
Author Response File: Author Response.pdf
