Evaluation of 4-Year Atmospheric Corrosion of Carbon Steel, Aluminum, Copper and Zinc in a Coastal Military Airport in Greece
Round 1
Reviewer 1 Report
The manuscript and the results are interesting, It can be published with fine revision of the English language and style.
Author Response
We thank the reviewer for the critical assessment of our work. A revision of the English language and style has been conducted. We believe that the contents and the clarity of our paper are much improved in the revised version.
Reviewer 2 Report
REVISION CMD-751891
The paper presents results about the atmospheric corrosion performance of some materials at a Greek location. It is an intensive work, with enough data related to atmospheric conditions, and results sound properly. I feel that some improvements have to be taken into account within the manuscript.
- Lines 28-30. Authors claim for costs about 3-6% GDP with 5 references. This statement must be split (due to GDP differences) and better explained.
- Line 127. Purity of Zn and Cu specimens is required.
- Line 133. Something seems missing in the coordinates of LGMG.
- 141-146 and 155-157. Specimens and information about procedure is repeated. Please, join all the information in the same paragraph, avoiding repetitions.
- Table 2. Write the chemical reagents in their chemical form instead of full names.
- 178: Include formulation to calculate TOW.
- Figure 3 is unclear. What is the black line? Which is the difference between red and blue bars? What are the numbers?
- Table 4. Between Cu and Zn there are two lines that can not be understood.
- In line 158, authors indicate they have carried out measurements after 3 and 6 months. Figures 4-7 are misleading. The upper part of each figure does not include data of 3 and 6 months. They MUST be included, as they will strongly affect the model (maybe they have been used, but they must appear in the plot). As far as I understand, the graph below (in each figure) is the same, but just including the prospective to 30 years. If this is the case, please remove them, as the 30-years value are included in Table 4. (Maybe one of the 4 materials can be left to show graphically the process, maybe including several materials). If it is not the case, please explain properly the difference.
- Lines 432-439. Although Zn and Cu compositions do not meet ISO 9226, I think it is interesting to indicate the values in Table 6 and 7, as it is done with steel and Al, and discuss them.
- Table 7 legend is misleading. Table includes results from first year; the writing of 5 years is misleading, and moreover, it is supposed it is a 4 year period what authors investigate.
- Please define PM (particulate matters) the first time it appears in the text (no later).
- Discussion should be divided in subparts (steel, Al,…) No sure about how to label last part (after Zn). Moreover, going back to comment 10, the data about Cu and Zn without adequate composition can be included in this discussion.
- Please shorten the conclusions.
Other minor things:
- Lines 18, 108, 117….: “Standards” (no “norms”)
- 40: “were” (no “have been carried”).
- 45: unclear, rewrite
- 101: “carried out” (no “touched and carried”)
- 143. A bracket is opened, no closed.
- 183. Subindex for 3 (AgNO3)
- 206,414: year (no “a”) – it occurs in other parts, please check.
- 217-8, something has moved.
- 219: seems “is employed” has no sense there.
- 274: “km” (no “Km”)
- 283: “is” (no “are”)
- 283-293: present and past tenses are mixed; maybe present is the adequate? Homogenize.
- Table 6, steel, C2: there is a strange symbol (not a number, 200)
Author Response
We thank the reviewer for the critical assessment of our work. A revision of the English language and style has been conducted. We believe that the contents and the clarity of our paper are much improved in the revised version. We address the points as follows:
- Lines 28-30. Authors claim for costs about 3-6% GDP with 5 references. This statement must be split (due to GDP differences) and better explained.
Lines 29-32: This sentence was revised as: According to Simillion et al [1], a corrosion cost at the range of 3-6% of the Gross Domestic Product (GDP) of the economies of the industrialized countries can be considered as common grounds of different studies [2-4]. Atmospheric corrosion constitutes a considerable part of this corrosion cost [5].
- Line 127. Purity of Zn and Cu specimens is required.
Line 125: Revised as requested (Purity of Zn and Cu specimens is added).
- Line 133. Something seems missing in the coordinates of LGMG.
Line 131: Coordinates of the LGMG are as they are.
- 141-146 and 155-157. Specimens and information about procedure is repeated. Please, join all the information in the same paragraph, avoiding repetitions.
The sentences 154 “Three test specimens of each metal and period of exposure were used for gravimetric analysis” and 157 “All samples were weighed before and after exposure.” were deleted.
- Table 2. Write the chemical reagents in their chemical form instead of full names.
Table 2. The chemical reagents have been written in their chemical form instead of full names (line 145).
- 178: Include formulation to calculate TOW
Lines 170-172 were revised as: T and RH data obtained by the data logger are also used for calculating the Time of Wetness (TOW). Τhe TOW is calculated as the length of time when the relative humidity is greater than 80% at a temperature greater than 0 °C [6].
- Figure 3 is unclear. What is the black line? Which is the difference between red and blue bars? What are the numbers?
Figure 3 (lines 204-207). The legend was modified as: Monthly variation of T (°C) and RH (%) data at the LGMG [60]. The black line represents the mean monthly temperature and its standard deviation at the LGMG. The red bar marks the hours per month where RH is over 80% and the blue bar marks the hours per month that RH is less than 80%. The numbers at the bottom are the TOW hours for each month. The numbers at the top are the hours where there is no wetness.
- Table 4. Between Cu and Zn there are two lines that can not be understood.
Lines 232-236 were modified and Table 5 (line 242) was added: Table 4 shows the corrosion rate of Cu for 1, 2 and 4 years determined experimentally, expressed in μm/year, given by the equation:
rcorr=Δm/(A ρ t) (2),
where Δm is the mass loss of Cu in g , A is the surface area in m2, t is the exposure time in years and ρ the density of Cu rcu=8.96 g/cm3 [9].
- In line 158, authors indicate they have carried out measurements after 3 and 6 months. Figures 4-7 are misleading. The upper part of each figure does not include data of 3 and 6 months. They MUST be included, as they will strongly affect the model (maybe they have been used, but they must appear in the plot). As far as I understand, the graph below (in each figure) is the same, but just including the prospective to 30 years. If this is the case, please remove them, as the 30-years value are included in Table 4. (Maybe one of the 4 materials can be left to show graphically the process, maybe including several materials). If it is not the case, please explain properly the difference.
Experimental data of 3 and 6 months are included on the plots (figures 4-7) as requested. Plots including the 30-year prospective of Steel, Cu and Zn are removed as requested.
- Lines 432-439. Although Zn and Cu compositions do not meet ISO 9226, I think it is interesting to indicate the values in Table 6 and 7, as it is done with steel and Al, and discuss them.
In this work there are 2 sets of experiments as follows:
A four-year period of outdoor exposure of Aluminum, Steel, Copper and Zinc specimens for the exposure years 2014 to 2018, starting winter and summer, was made. In addition, a set of 5 exposures for 12 months (from 2014 to 2019), starting winter and summer, for steel and aluminum was made, according to ISO and ASTM Standards in order to classify the atmospheric corrosivity and to examine the reliability of the CDA and the Europe and Asia Corrosion Map, regarding steel and aluminum, at the LGMG environment based both on environmental data and the corrosion rate measurements.
In contrast, Zn and Cu are only used for the 4 year experiment and do not follow the repeatability of the (multiple 1-year) measurements of steel and Al. Zn and Cu are mainly used as indicators for chloride deposition rate and sulphur compound concentration. Zn and Cu do not meet the requirements described by ISO 9226. The Standards require over 99.5 and 98.5 purity for Cu and Zn, respectively.
11.Table 7 legend is misleading. Table includes results from first year; the writing of 5 years is misleading, and moreover, it is supposed it is a 4 year period what authors investigate
The legend was modified as (lines 429-431): Table 8.: First-year of exposure corrosion rate of carbon steel and aluminum and ISO classification of the atmosphere severity at the LGMG according to ISO:9223 [6], after repeated experiments of one year period of outdoor exposure from 2014 to 2019.
- Please define PM (particulate matters) the first time it appears in the text (no later).
Revised as requested (first definition of PM in line 367).
- Discussion should be divided in subparts (steel, Al,…) No sure about how to label last part (after Zn). Moreover, going back to comment 10, the data about Cu and Zn without adequate composition can be included in this discussion.
The discussion is divided in subparts (lines 444, 536, 559).
- Please shorten the conclusions
The conclusion was shortened as requested.
- Lines 18, 108, 117….: “Standards” (no “norms”)
Revised as requested.
40: “were” (no “have been carried”).
Revised as requested [“were” (no “have been carried”).].
45: unclear, rewrite
Lines 47-50: Many studies [11,12] concluded that the decrease of the sulphur dioxide pollutant concentration in the atmosphere, the increase of the concentration of other types of air pollutants and the increase of the mean annual rainfall and temperature are the most important parameters changed over the course of the late 20th century, from the atmospheric corrosion aspect.
101: “carried out” (no “touched and carried”)
Revised as requested [“carried out” (no “touched and carried”)].
- A bracket is opened, no closed.
Revised as requested (A bracket is closed).
- Subindex for 3 (AgNO3)
Revised as requested
206,414: year (no “a”) – it occurs in other parts, please check.
Revised as requested
217-8, something has moved.
Revised as requested
219: seems “is employed” has no sense there.
Revised as requested (“is employed” was deleted)
274: “km” (no “Km”)
Revised as requested
283: “is” (no “are”)
283-293: present and past tenses are mixed; maybe present is the adequate? Homogenize.
Lines 280-289: Revised as requested (present tenses used, text is homogenized)
Table 6, steel, C2: there is a strange symbol (not a number, 200)
Table 6 was corrected
Reviewer 3 Report
Comments are attached as a separate file.
Comments for author File: 
Comments.pdf
Author Response
We thank the reviewer for the critical assessment of our work. A revision of the English language and style has been conducted. We believe that the contents and the clarity of our paper are much improved in the revised version. We address the points as follows:
Abstract Lines 15-21: Very long sentence. Also it is not clear which message the authors want to convey with this sentence.
The Abstract in general is poorly written.
Abstract was revised as: Atmospheric corrosion seriously affects the working life of construction metals. The quantitative knowledge of the corrosion effects helps the maintenance cost and the materials logistics. In this work, in a military airport sited by the sea, the corrosion damage equations of carbon steel, aluminum, zinc and copper are measured after outdoor exposure for 4 years. Exposure started at summer and winter for all cases. Weight loss was performed by gravimetry and the characterization of the exposed metal coupon surfaces by microscopy: optical, electron and atomic force, by X-ray diffraction and Fourier transform Infrared spectroscopy. Atmospheric conditions and pollutants were also evaluated. The derived corrosion equations of all tested metals for the exposure have been employed for the 30 year projection of expected corrosion. A parallel 12 month exposure of steel and aluminum -the most common airport metals, have been evaluated for 5 consequent years to designate the rating of the airport, according to ISO and ASTM Standards. The results showed that there is not a good correlation between the predictions of the Corrosion Damage Algorithm and the Europe and Asia Corrosion Map and the actual measurements on steel and aluminum at the site.
Line 28: corrosion is not a factor.
Line 28: “Results from several studies …” should be re-written.
Line 30: please remove the extra space between “of” and “their”.
Lines 29-32: These sentences ware revised as: Atmospheric corrosion is the main parameter in degradation of metallic materials. According to Simillion et al [1], a corrosion cost at the range of 3-6% of the Gross Domestic Product (GDP) of the economies of the industrialized countries can be considered as common grounds of different studies [2-4]. Atmospheric corrosion constitutes a considerable part of this corrosion cost [5].
Line 36: please remove the extra space between “rate” and “and”.
Line 34-37: please re-write: the sentence has an extra verb.
Line 36-39: As a result, Dose Response Functions (DRF) were established, based on meteorological data, SO2 concentration and chlorides (from NaCl) deposition rate. A general methodology for the classification of the atmospheric aggresivity started to emerge, based on the similarities of the methodologies of these programs.
Line 38: “atmospheric severity” should be replaced with a better and more representative expression.
Line 39: “atmospheric severity” replaced with “atmospheric aggresivity”
Line 43: please remove the extra space after the reference number.
Revised as requested
Lines 60-64: very long sentence. Please re-write it as two separate sentences.
Line 60-63: Pourbaix [16] and McCuen et al [17] proposed that a function of a 4-year corrosion versus time evolution is necessary in order to estimate the anticipated 30-year corrosion evolution of metals. Alternatively, in order to estimate the anticipated life-cycle of the manufactured products and infrastructures, a 10-year corrosion versus time evolution is necessary [16,17].
Line 71: please remove the extra space after the reference number.
Revised as requested.
Line 83 should read “as reliable methodologies”
Revised as requested
Line 96: Please remove the extra space after the first sentence.
Revised as requested
Line 118: CDA was already introduced in line 65.
Revised as requested
Line 121: please remove the extra space after “exposed”.
Revised as requested
Line 123: Please use unified units, either Km as it is used here or meters as in line 105.
Revised as requested (km was preferred as unit)
Line 127: Please use a space between “%” and “min”. Also “min” usually indicates minutes. Please use a better acronym.
Line 127: better to write as 100 x 100 x 1 mm.
Lines 124-127: Revised as requested
Line 128: What do authors mean by “current fabrication”?
The phrase “of current fabrication” was deleted
In Table 2, the degree C symbol looks inappropriate.
Table 2: Revised as requested
Line 157: “All samples were …” was already mentioned in previous paragraph.
The phrase “All samples were weighed before and after exposure.” was deleted.
Line 167: Please put a space after the sentence (if there is none).
Revised as requested
Line 174: Should read “Fourier Transform Infrared Spectrometer” (or spectroscopy).
Revised as requested (Fourier Transform Infrared Spectrometer was preferred).
Line 175: the “RH” should be defined here not in the next line.
Revised as requested (first definition of RH in line 168).
Line 176: The degree C symbol looks inappropriate.
Line 176: Revised as requested (The degree C symbol was corrected).
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Only format issues seem to appear in the document (Table 1 seems broken, Figure 3 legend seems to have a problem in the lines, Format in Lines 228-229; 245-246; Table 4, some data (b, R2) have split in two lines) that I suppose they have to be solved in a later stage of editing.
I acknowledge their effort.
Author Response
We thank the reviewer for the critical assessment of our work.
Table 1 was revised.
All format issues were checked and revised as requested.
Reviewer 3 Report
The manuscript “Evaluation of 4-Year Atmospheric Corrosion of Carbon Steel, Aluminum, Copper and Zinc in a Coastal Military Airport in Greece” presents an overwhelming amount of bulk data on atmospheric corrosion of carbon Steel, aluminum, copper, and zinc in an airport close to the shore. Most of the observations are based on the weight loss measurements as well as microscopic evaluations of the corroded samples after exposure for 1-5 year. different exposures started in winter or summer time to assess the role of initial atmospheric conditions on the evolution of the corrosion products in long run. An attempt is made to compare the experimentally obtained corrosion data with those predicted by standard models.
The predictive section of the manuscript is pretty weak. Also, the experimental evaluation of the samples is nothing beyond the standard reports in the industry. Nevertheless, I believe the manuscript could be potentially published in CMD after consideration of the following points.
Overall, the level of clarity of the manuscript text is quite low. The manuscript benefits immensely by re-writing the introduction section. In the revised introduction, the unnecessary historical facts could be removed and a more mechanistic description of the effect of atmospheric conditions on the corrosion of metals could be provided.
Line 13: Helps the maintenance costs is meaningless
Line 14: replace “sited” by “located”
Line 14: “equations” can not be measured
Line 16: “Exposure started at summer and winter”… how is that possible that exposures start at two different seasons…. Please correct (add “and” or “or” to the sentence) or re-write it as it is in line 126.
Line 16: “Weight loss” can not be performed… it should read “weight loss measurements were performed”. The rest of the sentence also required rephrasing
Line 33: “This has led to an extensive international effort to mitigate it” makes no sense.
Line 43: it should read “Morcillo et al.”
Line 53: A reference is required.
Line 71: an auxiliary verb is required to complete the sentence.
Line 77 and elsewhere: “et al.” is the correct form.
Line 80: “an ANN designed and trained” should be rephrased.
Line 81-87: a seven lines sentence is not appropriate. Please rephrase this extremely long sentence to few shorter ones. Also, please utilize proper punctuations to facilitate understanding your text.
Line 100: should read “indicate” instead of “indicating”. Also, this sentence is very long and hard to follow.
Line 106: replace “sited” by “located”
The data in Table 1 can not be seen.
Line 136: should read “due to the observation of macroscopic corrosion …”
Line 137: The selection of a site can not be correlated to the cost of aircraft inspection worldwide.
Line 180 should read “while a new sample was positioned”
Please stick to one tense (past or present) when presenting your experimental procedure. The alternative use of past and present tense makes the text hard to follow.
Line 217: Is this statement the outcome of this study? If yes, then I can not follow why the authors chose to add a reference at the end of this sentence. Similar issue exists in line 220.
Line 222: The reference 47 is misplaced.
Line 226: Please rephrase the sentence.
Figure 4: How good do you think the model can describe the data points in Figure 4?
Line 270: The reference 70 is misplaced in the sentence.
Line 272: Please re-write the sentence.
Line 301: How do the authors exclude the presence of amorphous corrosion products?
Are the XRD results in Figure 10 baseline corrected?
Is the IR spectrum in Figure 11 background corrected? It looks like the interferogram response rather than proper transmission spectrum.
Line 320: should read “independent” instead of “independently”
Line 324: Remove the extra space, please.
Line 328, please use either cuprite or (Cu2O). It is already been defined in the previous sentences.
Why did the authors refrain from using FTIR for characterization of corrosion products on Cu?
Line 337: “Zn shows the highest concentration of S among the tested metals,” makes no sense. I guess the authors refer to the concentration of S in the corrosion products on Zn samples.
It is strange to validate the low level of SO2 in the atmosphere by analyzing the corrosion products. In fact, the cause of level of pollutants should be observed by the effect (in this case, development of corrosion products and their composition), not the other way around.
The SEM images of the sample surfaces are provided with no further discussion.
Line 375. It is not clear which value refers to which sample side after which exposure period. Please either re-phrase the sentence or show the results in a table.
Line 400: Higher than what?
Line 471: I did not encounter any discussion related to the ozone in this study, though.
Either use “ “ or ‘ ‘ for the value “a”. The same with value “b”
Line 575: a reference is required.
Line 590: The text is misplaced.
Line 582: What are those interesting remarks?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 3
Reviewer 3 Report
I acknowledge the authors' efforts in implementing the reviewers' comments and updating their manuscript accordingly.
I am still not satisfied with the authors response to the following comment:
Line 301: How do the authors exclude the presence of amorphous corrosion products?
Are the XRD results in Figure 10 baseline-corrected?
Is the IR spectrum in Figure 11 background-corrected? It looks like the interferogram response rather than the proper transmission spectrum.
Also their response to the other comment for not using IR for assessment of the corrosion products on other samples than SS was not convincing.
Once the answers to the abovementioned issue are provided, the manuscript can be accepted for publication in Corros. Mater. Degrad.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
