Influence of UV Illumination on the Corrosion Behavior of New 3Ni Weathering Steel in Marine Atmospheric Environments

Round 1

Reviewer 1 Report

The paper presents important study of the influence of UV irradiance on the corrosion of steel in the marine environment. Paper could be published after addressing the following:

 

General comments

Abstract

- in two marine atmospheric environments

R: What kind of two environments?

time[1, 2].

Please through text add a space between references and last word.

page 2:….environment for a cycle, Carry out 48, 96, 192, 384 h…

Reviewer (R): Carry? -> carried out

page 3: UV illumination set illumination intensity of 1W/m2,

R: What was the UV sources? Also, 1 W/m2, (Also, through the whole text units should be written as W m^-2).

Page 2: Eq. 2 and the text below: T is the corrosion time, h.

R: T is thermodynamic temperature, t is quantity symbol for time.

Page 3: the three-electrode system of the VersaSTATMC workstation….

R: For all the equipment’s and chemicals, manufacturer, city and country should be added.

Page 3: An open-position circuit test was started for 3600 s. The polarisation curve was scanned at a rate of 0.167 mV/s, the potential interval scanned was -0.9 ~0.5 V…

R: “An open-position circuit test was started for 3600 s”- what is the meaning of this sentence, and what is the “open-position circuit test”.  “The polarisation curve was scanned”- scanned -> recorded?

page 3: The potential range of the M-S curves…

R: Mott-Schottky (M-S)

2.3. Electrochemical testing

R: Reference, counter electrodes and electrolyte must be mentioned.

ALSO, author stated that used “the three-electrode system”. Is it glass cell and is there any quartz or UV not absorbing window?????

3.2. electrochemical testing -> 3.2. Electrochemical testing

 

The main issue!

- The results show that UV illumination affects the corrosion process through the photovoltaic effect of the corrosion products, with photoelectrons and photo-vacancies participating in the redox reaction between the substrate and the atmospheric environment….

from the Introduction

 The β-FeooH, γ-FeooH, Fe2O3, CuO[11] and other metal oxides in the metal rust layer have semiconductor properties and produce photovoltaic effects; under the conditions of UV illumination, the entry of photogenerated electrons puts the electrons in the valence band (VB) of the corrosion products in an excited state and leap into the conduction band (CB), producing photogenerated holes, which can participate in oxidation reactions and photoelectrons in reduction reactions[12].

and from R&D

Tafel curves in both environments are almost identical in shape, with a corrosion potential of -610 mV and a corrosion current density of about 42 μA/cm2,

R: From Figure 2. it is obvious that UV has a positive effect on the decreasing the corrosion rate. Practically all the experiments suggest semiconducting properties of corrosion products. But polarization curves at both conditions are identical with the same current density and corrosion potentials? It is known that corrosion product are mainly n-type semiconductors, and under the UV irradiance negative shift of the corroded samples should be expected. So, reviewer will suggest that authors perform following test. Left the samples to corrode, and record the corrosion potentials with and without UV, for example 300/300 s. From the reviewer experience, the negative shift under UV serves as “cathodic protection”.

Author Response

Thank you for your affirmation of my work, for your questions and suggestions, I have made changes and labelling in the manuscript, for your questions, the corresponding responses are as follows:

1. For the marine environment, ultraviolet light source, dynamic potential polarisation curve and three-electrode system has been made to explain the explanation
2. t and units have been modified.
3. The manufacturer, city and country of the equipment have been modified.
4. For your explanation of cathodic protection for the experimental results, the polarisation curve does show a negative shift of corrosion potential and a decrease of self-corrosion current density, thank you for your correction.
5. for your proposed corrosion after 300s, determine the corrosion potential of the experiment, I have tested and analysis, but due to the corrosion time is short, the test environment, etc., it is difficult to come up with obvious rules, only the anodic polarisation curve of the pseudopassivation effect is obvious, and so the corrosion resistance is mainly through the results of the EIS to clarify.

Reviewer 2 Report

Authors in their study deal with the experimental research of the influence of UV illumination on the corrosion behavior of a certain weathering steel. The study seems reasonably well designed, and the conclusions are backed by the obtained results. The paper with its topic seems appropriate for the Metals journal, but there are some minor amendments to the paper rthat need to be addressed:

1. Examples of the specific use of the selected steel in marine structures should be given with possible failures due to UV illumination and corrosion, to justify the need for such research.

2. Results should be placed in the context of same/similar studies performed by other authors.

3. List of references should be expanded with publications of not only regional significance.

4. A comment on the possible comparison between results obtained in laboratory conditions and one obtained in real environment would be beneficial.

Minor English corrections.

Author Response

Thank you for your affirmation of my work, for your questions and suggestions, I have made changes and markings in the manuscript, for your questions, the corresponding responses are as follows:

1. in the introduction, has been described in the selected steel in the marine structure of the specific purpose, as well as the harsh marine environment may produce corrosion
2. As the experimental materials in this paper are designed by ourselves, the comparison is also designed for the corrosion behavior of experimental steel in two environments.
3. has been added in the introduction to the relevant references in the last three years
4. Comparable experimental results are fewer, while we have been in the actual environment for a long time hanging film experiments, comparison results will be described later.

Round 2

Reviewer 1 Report

Dear authors,

Thanks for answering to all the questions. Paper can be accepted now.

Notice to authors: you incorrectly understand me. I proposed that you left the sample to corrode few days, and than to record corrosion potential vs time with UV on/of for approximately 300/300 s. But, maybe next time and be sure tu use quartz window, Pyrex glass adsorb most of the UV light.

Best wishes