The Construction of a Small-Caliber Barrel Wear Model and a Study of the Barrel Wear Rule
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript "Construction of small-caliber barrel wear model and study of barrel wear rule" contains many understatements and inaccuracies that require clarification.
General remarks
1. In chapter 2.2, write how the Hardness test was performed.
2. The standard deviation from the average values should be shown in Fig.4.
3. Authors should show in the manuscript the standard deviation (SD) and (COV) of the values presented in Fig. 4 and Fig. 17.
4. Please write how many samples were tested in total in the mentioned types of tests.
Specific remarks
5. In Eq.1, write in what units the quantities are expressed.
6. In Eq.2, write what N and L mean.
7. In Eq.3, write the units in which the quantities k, N, H are expressed.
8. Fig.2: Write what the blue rectangles in the drawing mean.
9. Fig.4: It should read: "Temperature and Hardness of coating material".
10. Tab.2 and Fig.6: The authors should decide what the load was: 40 N or 400 N.
11. In Eq.4, write in what units the quantities are expressed.
12. In the text under Eq.4, decide what the designations a or α and b or β should be.
13. In Eq.6, 7 you should write in what units the quantities are expressed.
14. Fig.8: The types of surfaces should be described in the article.
15. Fig.9c, d: The ordinate axis should contain the force units N. In addition, the types a, b, c, d should be described in the article.
16. Fig. 11: Write down the range of thread pitch due to the "normalized distance".
17. Fig.16: The number of bullets should be shown on the abscissa.
18. Chapter 4: Should be “Conclusions.”
The article may be published after thorough revision in the Coatings.
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
Comments1:In chapter 2.2, write how the Hardness test was performed.
Response1: [The microhardness of the coating was determined by HVS-1000 digital microhardness tester. In order to avoid the influence of the substrate, the microhardness of the coating is measured along the cross section. Before measurement, the coating sample is cut along the cross section, sealed with epoxy resin, ground and polished, and then measured. Each sample measures 8 to 10 points, and the average value is taken as the final data. The chrome-plated samples were heated at 25℃, 200℃, 300℃, 400℃, 500℃, 600℃, and 700℃, and then air-cooled to room temperature.]. Thank you for pointing this out. We agree with this comment. Therefore, we supplement the hardness test method, In chapter 2.2, the first paragraph.
Comments2: The standard deviation from the average values should be shown in Fig.4.
Response2: [The temperature of multiple sections of the gun barrel during the entire shooting process was integrated and averaged, and the average temperature of each section the coating material , as shown in Fig 4 (a). By calculating the heat transfer of the barrel and combining with formula (4), we calculated the coating hardness values at different coaxial positions of the barrel (200mm, 250mm, 300mm, 350mm, 400mm and 450mm), and plotted the curve changes in Fig 4 (b).] Thank you for pointing this out. We agree with this comment. We did not make the meaning of Fig 4 clear, so we added a supplementary explanation. Add details to the top and bottom paragraphs of Fig 4.
Comments3: Authors should show in the manuscript the standard deviation (SD) and (COV) of the values presented in Fig. 4 and Fig. 17.
Response3: Thank you for pointing this out. As for the comment of Fig 4, we explained it in detail in the last reply. As for Fig 17, we would like to make an explanation. Fig 17 shows that we calculated the rifling wear depth through the wear model, and made a comparison with the actual pipe wear to show the accuracy of the wear model we proposed. Therefore, Fig 17 is not an error analysis.
Comments4: Please write how many samples were tested in total in the mentioned types of tests.
Response4: Thank you for pointing this out. In the coating hardness test, we used 10 samples, of which 2 samples were backup samples; In the high-temperature pin plate wear test, we used 12 samples, including 3 samples at 550°, 3 samples at 400°, 3 samples at 250°, and the rest were backup samples. In the actual shooting test of the barrel, 2 samples were used.
Comments5: In Eq.1, write in what units the quantities are expressed.
Response5: Agree. We have accordingly modified the units in the Eq. 1 to emphasize this point. Mention exactly where in the revised manuscript this change can be found Eq1
Comments6: In Eq.2, write what N and L mean.
Response6: Agree. In Eq.2, N and L is and of Eq.1. Mention exactly where in the revised manuscript this change can be found Eq.2.
Comments7: In Eq.3, write the units in which the quantities k, N, H are expressed.
Response7: Agree. is dimensionless wear coefficient, N is is normal load (N), which is , is the material hardness. Mention exactly where in the revised manuscript this change can be found Eq.3.
Comments8: Fig.2: Write what the blue rectangles in the drawing mean.
Response8: Agree. the blue rectangles in the drawing mean is the the coating interface temperature change distance 200 mm from the gun barrel tail. The remaining curves represent the temperature change curves at different positions of the barrel.
Comments9: Fig.4: It should read: "Temperature and Hardness of coating material".
Response9: Agree. Mention exactly where in the revised manuscript this change can be found Fig.4.
Comments10: Tab.2 and Fig.6: The authors should decide what the load was: 40 N or 400 N.
Response10: Agree. We decide the load is 400N. Mention exactly where in the revised manuscript this change can be found Tab.2 and Fig.6.
Comments11: In Eq.4, write in what units the quantities are expressed.
Response11: Agree. Mention exactly where in the revised manuscript this change can be found Eq.4.
Comments12: In the text under Eq.3, decide what the designations a or α and b or β should be.
Response12: 、 、 and are undetermined coefficients. In the following research, we get the specific value by combining simulation and experiment
Comments13: In Eq.6, 7 you should write in what units the quantities are expressed.
Response13: Agree. Mention exactly where in the revised manuscript this change can be found Eq.6, 7.
Comments14: Fig.8: The types of surfaces should be described in the article.
Response14: Agree. Mention exactly where in the revised manuscript this change can be found Fig.8 (e).
Comments15: Fig.9c, d: The ordinate axis should contain the force units N. In addition, the types a, b, c, d should be described in the article.
Response15: Fig.9 is the the curve of friction velocity. Figure 9 is just one diagram, and there is no a,b,c,d.
Comments16: Fig. 11: Write down the range of thread pitch due to the "normalized distance".
Response16: Agree. The normalized distance refers to the circumference of the rifling, which is composed of 6 rifling lines, that is the distance 1.
Comments17: Fig.16: The number of bullets should be shown on the abscissa.
Response17: Agree. Mention exactly where in the revised manuscript this change can be found Fig.16.
Comments18:. Chapter 4: Should be “Conclusions.”
Response18: Agree. We have modified.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis research investigates the friction and wear between the inner chamber of the barrel and the projectile at high temperature, high speed and high pressure, and the establishment of the barrel wear model for the development of the wear-resistant barrel suitable for high pressure firing conditions. The authors should incorporate the following suggestions:
1. Please provide complete address for the affiliation institutes for all authors.
2. Please provide the details how the hexavalent chromium coating material is deposited as shown in figure 1?
3. What is the thickness of the coating?
4. Please provide the make and model details of the Vickers hardness tester.
5. What was the penetration depth to measure the hardness of the coating?
6. Please elaborate the details on the set-up and how the hardness was measured at higher temperatures of up to 700C as mentioned in table 1.
7. How many measurements were taken for the values?
8. Explain how the coating interface temperature change between 200 and 463mm from the gun barrel tail as shown in figure 2 was measured?
9. There is no caption of figure 3 as discussed in manuscript as there si directly figure 4(a) and (b) after figure 2, please include figure 3 or re-name figure 4.
10. Please provide the details how the temperature of multiple sections of the gun barrel during the entire shooting process was measured, integrated and averaged?
11. Please provide complete figure captions for figures 8,9,10 as the present one sounds incomplete and seems missing information such as ‘Figure 9. The curve of friction velocity’ for what conditions, details?
12. Please provide the make and mode details of the microscope for the figure 13.
13. Please provide the make and mode details of the microscope for the images take in figure 15.
14. Please elaborate the experimental details on how the wear morphology of barrel muzzle in mid-life and at the end of the barrel was calculated.
15. The authors should include an experimental details section and elaborate the experimental details on how the friction velocity, pressure, force, and wear were measured?
Comments on the Quality of English Language
The English language and figure captions needs to be checked by an expert.
Author Response
Comments1: Please provide complete address for the affiliation institutes for all authors.
Response1: Agree. Mention exactly where in the revised manuscript this change can be found introduction of the author.
Comments2: Please provide the details how the hexavalent chromium coating material is deposited as shown in figure 1?
Response2: I am sorry. how the hexavalent chromium coating material is deposited is not this paper research scope. In addition, the chromium plating process is more complicated. This paper only studies the wear rule of the tube after chromium plating.
Comments 3: What is the thickness of the coating?
Response3: The thickness of the coating is 90 um.
Comments 4: Please provide the make and model details of the Vickers hardness tester.
Response4: HVS-1000 digital microhardness tester. The hardness of chromium plating layer was tested by 100g, 300g and 500g load respectively
Comments 5: What was the penetration depth to measure the hardness of the coating?
Response5: The penetration depth to measure the hardness of the coating is 20 um
Comments 6: Please elaborate the details on the set-up and how the hardness was measured at higher temperatures of up to 700C as mentioned in table 1.
Response6: The microhardness of the coating was determined by HVS-1000 digital microhardness tester. In order to avoid the influence of the substrate, the microhardness of the coating is measured along the cross section. Before measurement, the coating sample is cut along the cross section, sealed with epoxy resin, ground and polished, and then measured. Each sample measures 8 to 10 points, and the average value is taken as the final data. The chrome-plated samples were heated at 25℃, 200℃, 300℃, 400℃, 500℃, 600℃, and 700℃, and then air-cooled to room temperature.
Comments 7: How many measurements were taken for the values?
Response7: In the coating hardness test, we used 10 samples, of which 2 samples were backup samples; In the high-temperature pin plate wear test, we used 12 samples, including 3 samples at 550°, 3 samples at 400°, 3 samples at 250°, and the rest were backup samples. In the actual shooting test of the barrel, 2 samples were used.
Comments 8: Explain how the coating interface temperature change between 200 and 463mm from the gun barrel tail as shown in figure 2 was measured?
Response8: The coating interface temperature change between 200 and 463mm from the gun barrel tail is obtained by simulation calculation.
Comments 9: There is no caption of figure 3 as discussed in manuscript as there si directly figure 4(a) and (b) after figure 2, please include figure 3 or re-name figure 4.
Response9: Agree. Mention exactly where in the revised manuscript this change can be found all figures.
Comments 10: Please provide the details how the temperature of multiple sections of the gun barrel during the entire shooting process was measured, integrated and averaged?
Response10: During the shooting process of the barrel, we processed blind holes in different positions of the barrel (the distance between the blind holes and the inner surface of the barrel is 3mm), installed high sensitivity temperature sensors in the blind holes, measured the temperature there, combined with calculation, and obtained the surface temperature of the barrel
Comments 11: Please provide complete figure captions for figures 8,9,10 as the present one sounds incomplete and seems missing information such as ‘Figure 9. The curve of friction velocity’ for what conditions, details?
Response11: FIG. 8,9 and 10 are the curve rules calculated by the finite element model in Section 2.4. For detailed finite element simulation, please refer to the literature[20-21].
Comments 12: Please provide the make and mode details of the microscope for the figure 13.
Response12: Nova NanoSEM450 field emission scanning electron microscope was used.
Comments 13: Please provide the make and mode details of the microscope for the images take in figure 15.
Response13: The morphology of the bore was characterized by three-dimensional macroscopic imaging (3DIHM), optical microscope (OM) and scanning electron microscope (SEM)
Comments 14: Please elaborate the experimental details on how the wear morphology of barrel muzzle in mid-life and at the end of the barrel was calculated.
Response14: 7 sections of samples were intercepted by wire cutting at 120-130mm, 195-205mm, 270-280mm, 360-370mm, 455-465mm (starting from the tail of the barrel).The sample was put into acetone solution and cleaned by ultrasonic wave. The morphology of the bore was characterized by three-dimensional macroscopic imaging (3DIHM), optical microscope (OM) and scanning electron microscope (SEM). The cold-mounted sample was polished and corroded with 2% (volume fraction) nitrate alcohol, and the microstructure was observed by OM and SEM.
Comments 15: The authors should include an experimental details section and elaborate the experimental details on how the friction velocity, pressure, force, and wear were measured?
Response15: Experimental details of how to measure friction velocity, pressure, force, and wear. Considering that there are more contents in this aspect, we have sorted out a separate research report in this aspect, which will be published later.
Reviewer 3 Report
Comments and Suggestions for AuthorsI have a few small comments on the submitted article.
1. Add specific measured values (results) to the end of the abstract. not just general information.
2. Expand the number of literary references in the introduction, there are several authors who researched coatings as well as materials intended for barrels, for example in the article Contact Fatigue Resistance of Gun Barrel Steels
3. At the end of the abstract, add the main goal of the article as well as the measurement methods.
4. Write down the value of the load when measuring the hardness Hv. Add this information to the text as well as to figure 1b and 3b
5. check the entire text, it contains many typos in the form of text without spaces.
6. It is necessary to elaborate more on the text about the results in Figure 2.
7. Fig. 3 and 3b have the same descriptions, it is necessary to distinguish them.
8. Why did you use a friction time of 15 min?
9. Table 2 why a different rotation speed and linear velocity is used in the last line.
10. Fig. 5 It is not sufficient to measure the wear micrographs, it is also necessary to perform the wear mechanism on these images. You can be inspired by many articles that deal with wear mechanisms, such as Analysis of Tribological Properties of Powdered Tool Steels M390 and M398 in Contact with Al2O or Dry Sliding Friction of Tool Steels and Their Comparison of Wear in Contact with ZrO2 and X46Cr13.
11. Why are different font sizes used in text and formulas on page 6.
12. Fig. 7 when you have it divided into five parts, it is necessary to refer to each picture in the text.
13. Enlarge most of the images or the text on the axes of the images, this should be done for better readability.
14. Conclusion 1 is only general, it does not describe any specific results (measured values).
15. Conclusion 2 to add concrete pressure values.
16. Conclusion 4 is only a recommendation - remove,
16. Add a discussion chapter where the authors compare their results with similar articles. This will also increase the total number of citations
Overall, the article is written only theoretically, it contains results (tables, graphs) that also require an explanation, the article is also poorly processed in terms of graphics, better wear results are needed (the use of a SEM microscope followed by EDX analysis of friction surfaces, it would also be it is also appropriate to determine the friction coefficient for wear measurements. The article needs significant improvements in order to be published in this journal, it also needs additional measurements that are time-consuming, and therefore I do not recommend the article to be defended now. I recommend that the article be revised according to the comments and submitted for publication again don't worry.
Author Response
Comments1: Add specific measured values (results) to the end of the abstract. not just general information.
Response1: Agree. We came to a clear conclusion：100mm away from the tail of the barrel is the junction between the shell and the projectile, before which the inner wall of the barrel wears very fast, and this position is the cone of the bullet embedded in the shell. At the position 150mm~350mm away from the tail of the gun, the inner wall of the barrel is worn from small to large, and this part of the barrel chrome layer is mainly affected by gunpowder impact and projectile extrusion. This is consistent with the actual failure of the coating. When the distance to the tail of the barrel is 350m, the wear becomes stable. Through the analysis of the diameter of the barrel, it is found that when the diameter of the barrel exceeds 12.85mm, the barrel will reach the end of its life.
Comments2: Expand the number of literary references in the introduction, there are several authors who researched coatings as well as materials intended for barrels, for example in the article Contact Fatigue Resistance of Gun Barrel Steels
Response2: Agree. In the introduction we have added research papers related to barrel materials
Comments3: At the end of the abstract, add the main goal of the article as well as the measurement methods.
Response3: After the first sentence of the summary, the following is added: Combined with the high temperature pin-plate wear experiment, actual firing test and finite element simulation calculation, the force and wear laws of the rifling of the barrel were studied.
Comments4: Write down the value of the load when measuring the hardness Hv. Add this information to the text as well as to figure 1b and 3b.
Response4: The load 300g is added at the end of figure 1b and 3b.
Comments5: check the entire text, it contains many typos in the form of text without spaces.
Response5: Agree. We just corrected the mistakes in the article.
Comments6: It is necessary to elaborate more on the text about the results in Figure 2.
Response6: Agree. We covered the contents of Figure 2 in detail：According to the one-dimensional heat conduction equation of the barrel[19], the temperature variation curve of the coating interface at 200~463mm distance from the barrel tail under the condition of 150 consecutive shots (including 10 short shots and 20 and 30 long shots) was calculated by taking the maximum temperature of the gunpowder gas as the heat source and considering the effect of the heat transfer coefficient of the gas-solid interface. After 150 rounds of firing, the barrel surface temperature reached 700 ℃, and the temperature at the interface between the coating and the substrate material was about 420 ℃. It can be seen from the temperature curve that the temperature change of the barrel will affect the hardness of the coating.
Comments7: Fig. 3 and 3b have the same descriptions, it is necessary to distinguish them.
Response7: Agree. For Fig.3 and 3b, we made the following modifications: In order to grasp the relationship between the coating temperature and hardness changes at different positions of the gun barrel axis, the average temperature and hard-ness of the coating material were obtained from the surface and interface temperature of the coating according to the calculation results of the gun barrel temperature field. As shown in FIG. 3 (a), the temperature change curve of the gun barrel coating from 200mm to 450mm is shown. The average coating temperature is about 119℃. Combined with formula (4), the coating hardness values of different coaxial positions of the barrel (200mm, 250mm, 300mm, 350mm, 400mm, 450mm) can be calculated, as shown in Fig-ure 3 (b).
Comments8: Why did you use a friction time of 15 min?
Response8: the friction time of 15 min is In order to ensure that the 0.02mm thickness of the coating can be completely worn, at the same time to achieve wear on the base material.
Comments9: Table 2 why a different rotation speed and linear velocity is used in the last line.
Response9: During the test, in order to record more test conditions and data, we recorded both linear speed and angular speed. Of course we can keep the linear velocity or the angular velocity one or the other.
Comments10: Fig. 5 It is not sufficient to measure the wear micrographs, it is also necessary to perform the wear mechanism on these images. You can be inspired by many articles that deal with wear mechanisms, such as Analysis of Tribological Properties of Powdered Tool Steels M390 and M398 in Contact with Al2O or Dry Sliding Friction of Tool Steels and Their Comparison of Wear in Contact with ZrO2 and X46Cr13.
Response10: Agree. We have added the abrasion marks of the sample and EDS line scan results on page 6 of the article.
Comments11: Why are different font sizes used in text and formulas on page 6.
Response11: Agree. We have changed this.
Comments12: Fig. 7 when you have it divided into five parts, it is necessary to refer to each picture in the text.
Response12: Agree. We have changed this. Figure 7 (e) is illustrated as a separate figure.
Comments13: Enlarge most of the images or the text on the axes of the images, this should be done for better readability.
Response13: Agree. We have changed this.
Comments14: Conclusion 1 is only general, it does not describe any specific results (measured values).
Response14: Agree. After comprehensive consideration, we decide to delete conclusion 1
Comments15: Conclusion 2 to add concrete pressure values.
Response15: Agree.
Comments16: Conclusion 4 is only a recommendation - remove,
Response16: Agree. After comprehensive consideration, we decide to delete conclusion 1.
Comments17: Add a discussion chapter where the authors compare their results with similar articles. This will also increase the total number of citations
Response17: We have checked the relevant literature, and there are few studies on gun barrel coating wear. If compared with other steel wear literature, but the research conditions are very different, so we do not compare other literature.
Reviewer 4 Report
Comments and Suggestions for AuthorsThe topic is of interest, and the method is well planned. But the language needs improvement. Like the titel Fig.2: different (better use various). Section 3.2 - here the grammar needs improvement. Please carefully read and improve the language style.
For the introduction you can also cite literature about Archard wear model used for roller bearings under high pressure (like DOI:10.3390/lubricants8020016)
Comments on the Quality of English LanguageThe language needs extensive improvement.
Author Response
Thank you very much for your valuable comments. We have revised the language and text according to your comments, and supplemented the references, such as reference [22]. Thanks again!
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe revised manuscript looks better after including the suggestions from the reviewer and can be accepted in the present form.
Comments on the Quality of English LanguageMinor editing of English language from an expert is required.
Author Response
Thank you very much. We have revised the English quality of the article.
Reviewer 3 Report
Comments and Suggestions for AuthorsThanks to the authors for answering my questions and comments. I still have some small but rather small comments:
1. shorten the abstract to 200 words, remove theoretical sentences
2. Remove fig. 1a
3. Increase the font size in Tables
4. Change the font of the text in Figure 6
5. Fig. 7. what elements are indicated by the EDS color graphs, it is necessary to describe these results specifically why the individual elements occur in a given amount in a given part of the friction groove.
Author Response
Comments1: shorten the abstract to 200 words, remove theoretical sentences
Response1: Thank you. We have revised the summary.
Comments2: Remove fig. 1a
Response2: Agree.
Comments3: Increase the font size in Tables
Response3: Agree. We have changed the font size in Tables
Comments4: Change the font of the text in Figure 6
Response4: Agree. We have changed.
Comments5: Fig. 7. what elements are indicated by the EDS color graphs, it is necessary to describe these results specifically why the individual elements occur in a given amount in a given part of the friction groove.
Responses5: Agree. We added descriptions of elements in the EDS diagram. We have added a paragraph above Figure 6 explaining this phenomenon. “In the friction process, because the copper ball and the chromium plating layer contact, the force in the middle of the wear mark is large, the force on both sides is small, and the hardness of the copper ball is less than the hardness of the chromium plating layer, so the copper ball will be worn off, but not enough to form a wear mark on the surface of the chromium plating layer; The width of the abrasion mark is larger than the width of the copper adhesive, indicating that the copper adhesive first appears in the middle part of the heavy force, and the adhesion expands to both sides. At the same time, the thickness of the copper adhesive is also different under the influence of the flatness of the surface of the chrome layer.”
