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Pitting corrosion

From Wikipedia, the free encyclopedia
Severe pitting corrosion problems caused bychlorideions on a truss beam of theNandu River Iron Bridge(HainanProvince, China) leading to the complete rupture of a metallic element.

Pitting corrosion,orpitting,is a form of extremely localizedcorrosionthat leads to therandomcreation of small holes in metal. The driving power for pitting corrosion is thedepassivationof a small area, which becomesanodic(oxidation reaction) while an unknown but potentially vast area becomescathodic(reduction reaction), leading to very localizedgalvanic corrosion.The corrosion penetrates the mass of the metal, with a limited diffusion of ions.

Another term arises, pitting factor, which is defined as the ratio of the depth of the deepest pit (resulting due to corrosion) to the average penetration, which can be calculated based on the weight loss.

Development and kinetics of pitting

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According to Frankel (1998) who performed a review on pitting corrosion, it develops in three successive steps:(1) initiation(ornucleation) by breakdown of the passive film protecting the metal surface from oxidation, (2) growth of metastable pits (growing up to the micron scale and then repassivating), and (3) the growth of larger and stable pits.[1]

The evolution of the pit density (number of pits per surface area) as a function of time follows a sigmoid curve with the characteristic shape of alogistic functioncurve, or ahyperbolic tangent.[2]Guo et al. (2018), after a statistical analysis of hundreds of individual pits observed on carbon steel surfaces at the nano-to-micro- scales, distinguish three stages of pitting corrosion: induction, propagation, and saturation.[2]

Mechanism

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The pit formation can be essentially regarded as a two step process: nucleation followed by a growth.

Depassivation of the protective layer

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The process of pit nucleation is initiated by thedepassivationof the protective oxide layer isolating the metal substrate from the aggressive solution. The depassivation of the protective oxide layer is the less properly understood step in pitting corrosion and its very local and random appearance probably its most enigmatic characteristic. Mechanical or physical damages may locally disrupt the protective layer. Crystalline defects, or impurity inclusions, pre-existing in the base metal material can also serve as nucleation points (especially metal sulfide inclusions). The chemical conditions prevailing in the solution and the nature of the metal, or the alloy composition, are also important factors to take into consideration. Several theories have been elaborated to explain the depassivation process.Anionswith weak or strongligandproperties such aschloride(Cl−
) andthiosulfate(S
2O2−
3) respectively can complex the metalliccations(Men+) present in the protective oxide layer and so contribute to its local dissolution. Chloride anions could also compete withhydroxide ions(OH−
) for the sorption onto the oxide layer and start to diffuse into the porosity or the crystal lattice of the oxide layer. Finally, according to the point-defect model elaborated by Digby Macdonald, the migration of crystal defects inside the oxide layer could explain its random localized disappearance.[3][4][5]The main interest of the point-defect model is to explain thestochasticcharacter of the pitting corrosion process.

Pit growth

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Schematic diagram showing the mechanism of localized corrosion with anodic zone (Fe oxidized intoFe2+
inside the pit) and cathodic zone (O2reduced intoOH−
elsewhere outside the pit) developing on a metal immersed into an aqueous solution containing dissolved oxygen. Here, the pH conditions are neutral or alkaline (presence ofOH−
ions in solution). The transport of ions occurs into the aqueous solution while electrons are transported from the anode to the cathode via the base metal (electrical conductor).

The more common explanation for pitting corrosion is that it is anautocatalyticprocess driven by the random formation of smallelectrochemical cellswith separateanodicandcathodiczones. The random local breakdown of the protective oxide layer and the subsequentoxidationof the underlying metal in the anodic zones result in the local formation of a pit where acid conditions are maintained by the spatial separation of the cathodic and anodic half-reactions. This creates agradientofelectrical potentialand is responsible for theelectromigrationof aggressiveanionsinto the pit.[6]For example, when ametalis exposed to an oxygenatedaqueous solutioncontainingsodium chloride(NaCl) aselectrolyte,the pit acts as anode (metal oxidation) and the metal surface acts as cathode (oxygen reduction).

In the case of pitting corrosion ofiron,orcarbon steel,by atmosphericoxygendissolved in acidic water (pH< 7) in contact with the metal exposed surface, the reactions respectively occurring at the anode and cathode zones can be written as follows:

Anode:oxidationof iron: 2 (Fe → Fe2++ 2e−)
Cathode:reductionof oxygen:O2+ 4H++ 4e−→ 2 H2O
Globalredoxreaction:2 Fe + O2+ 4 H+→ 2 Fe2++ 2 H2O

Acidic conditions favor the redox reaction according toLe Chatelier principlebecause the H+ions added to the reagents side displace the reaction equilibrium to the right and also increase the solubility of the releasedFe2+
cations.

Under neutral to alkaline conditions (pH> 7), the set of redox reactions given here above becomes the following:

Anode:oxidationof iron: 2 (Fe → Fe2++ 2e−)
Cathode:reductionof oxygen:O2+ 2 H2O + 4e−→ 4 OH−
Globalredoxreaction:2 Fe + O2+ 2 H2O → 2 Fe(OH)2

TheprecipitationofFe(OH)2(green rust) can also contribute to drive the reaction towards the right. However, thesolubilityofFe(OH)2(Fe2+) is relatively high (~ 100 times that ofFe3+), but strongly decreases when pH increases because ofcommon ion effectwith theOH−.

In the two examples given here above:
– Iron is a reductant giving electrons while being oxidized.
– Oxygen is an oxidant taking up electrons while being reduced.

The formation of anodic and cathodic zones creates anelectrochemical cell(i.e.,a smallelectric battery) at the surface of the affected metal. The difference inGibbs free energy(ΔG) drives the reaction because ΔG is negative and the system releases energy (enthalpy,ΔH < 0) while increasingentropy(ΔG = ΔH - TΔS).

The transport of dissolvedionsoccurs into theaqueous solutionin contact with the corroding metal while electrons are transported from the anode (giving e−) to the cathode (accepting e−) via thebase metal(electrical conductor).

The localized production of positive metalcations(Men+,Fe2+in the example here above) in the pit (oxidation: anode) gives a local excess of positive charges which attract the negative ions (e.g., the highly mobile chlorideanionsCl−
) from the surroundingelectrolyteto maintain the electroneutrality of the ion species inaqueous solutionin the pit. The pit contains a high concentration of metal (Me) chloride (MeCln) whichhydrolyzeswith water to produce the corresponding metal hydroxide (Me(OH)n), and n H+and n Cl–ions, accelerating the corrosion process.[7]

In the case of metallic iron, or steel, the process can be schematized as follows:[8]

Fe2++ Cl−→ [FeCl complex]+
[FeCl complex]++ 2 H2O → Fe(OH)2+ 2 H++ Cl−

Under basic conditions, such as under the alkaline conditions prevailing in concrete, the hydrolysis reaction directly consumes hydroxides ions (OH−
) while releasing chloride ions:

[FeCl complex]++ 2 OH−→ Fe(OH)2+ Cl−

So, when chloride ions present in solution enter in contact with the steel surface, they react withFe2+of the passive layer protecting the steel surface and form an iron–chloride complex. Then, the iron-chloride complex reacts with theOH−anions produced by the water dissociation and precipitatesferrous hydroxide(Fe(OH)2) while releasing chloride ions and new H+ions available to continue the corrosion process.

In the pit, the oxygen concentration is essentially zero and all of the cathodic oxygen reactions take place on the metal surface outside the pit. The pit is anodic (oxidation) and the locus of rapid dissolution of the metal.[9]The metal corrosion initiation is autocatalytic in nature however its propagation is not.

This kind of corrosion is often difficult to detect and so is extremely insidious, as it causes little loss of material with the small effect on its surface, while it damages the deep structures of the metal. The pits on the surface are often obscured by corrosion products. Pitting can be initiated by a small surface defect, being a scratch or a local change in thealloycomposition (or local impurities,e.g.metallicsulfideinclusions such asMnSorNiS),[10][11]or a damage to the protective coating.Polished surfacesdisplay a higher resistance to pitting.[12]

Capillary electrophoresis in the pit

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In order to maintain the solution electroneutrality inside the pit populated by cations released by oxidation in the anodic zone (e.g.,Fe2+
in case of steel), anions need to migrate inside the narrow pit. It is worth to notice that theelectromobilitiesofthiosulfate(S
2O2−
3) andchloride(Cl−
) anions are the highest after these of H+and OH−ions in aqueous solution. Moreover, themolar conductivityof thiosulfate ions is even higher than that of chloride ions because they are twice negatively charged (weak base reluctant to accept a proton). Incapillary electrophoresis,thiosulfate moves faster than chloride and eluates before this latter. The high electromobility of both anions could also be one of the many factors explaining their harmful impact for pitting corrosion when compared with other much less damaging ion species such asSO2−4andNO−3.

Susceptible alloys and environment conditions

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Pitting corrosion is defined by localized attack, ranging from microns to millimeters in diameter, in an otherwise passive surface and only occurs for specific alloy and environmental combinations. Thus, this type of corrosion typically occurs in alloys that are protected by a tenacious (passivating) oxide film such as stainless steels, nickel alloys, aluminum alloys in environments that contain an aggressive species such as chlorides (Cl–) or thiosulfates (S2O32–). In contrast, alloy/environment combinations where the passive film is not very protective usually will not produce pitting corrosion. A good example of the importance of alloy/environment combinations iscarbon steel.In environments where thepHvalue is lower than 10, carbon steel does not form apassivatingoxide film and the addition of chloride results in uniform attack over the entire surface. However, at pH greater than 10 (alkaline) the oxide is protective and the addition of chloride results in pitting corrosion.[13]

Besides chlorides, other anions implicated in pitting includethiosulfates(S2O32−),fluoridesandiodides.Stagnant water conditions with low concentrations of dissolved oxygen also favor pitting. Thiosulfates are particularly aggressive species and are formed by partialoxidation of pyrite(FeS2,a ferrous disulfide), or partialsulfate reduction by microorganisms,a.o. bysulfate reducing bacteria(SRB). Thiosulfates are a concern for corrosion in many industries handling sulfur-derived compounds:sulfideores processing,oil wellsand pipelines transporting soured oils,kraft paperproduction plants, photographic industry,methionineandlysinefactories.

Influence of redox conditions

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See also:Pourbaix diagram

Although in the aforementioned example, oxic conditions were always considered with the reduction of dissolvedO2in the cathodic zones, pitting corrosion may also occur under anoxic, or reducing, conditions. Indeed, the very harmful reduced species of sulfur (H2S,HS−
,S2−
,HS–S−
,−
S–S−
,S0andS
2O2−
3) can only subsist under reducing conditions.[14]Moreover, in the case of steel and stainless steel, reducing conditions are conducive to the dissolution of the protective oxide layer (dense γ-Fe
2O
3) becauseFe2+
is much more soluble thanFe3+
,and so reducing conditions contribute to the breakdown of the protective oxide layer (initiation, nucleation of the pit). Reductants exert thus an antagonist effect with respect to the oxidants (chromate, nitrite) used as corrosion inhibitors to induce steel repassivation via the formation of a dense γ-Fe
2O
3protective layer. Pitting corrosion can thus occur both under oxidizing and reducing conditions and can be aggravated in poorly oxygenated waters by differential aeration, or by drying/wetting cycles.

Under stronglyreducing conditions,in the absence of dissolved oxygen in water, or pore water of the ground, theelectron acceptor(oxidizing agent) at thecathodic sites,where reduction occurs, can be the protons ( H+) of water itself, the protons ofhydrogen sulfide(H2S), or in acidic conditions in case of severepyrite oxidationin a former oxic atmosphere, dissolved ferric ions (Fe3+
), known to be very potentoxidizers.The presence of harmful reduced species of sulfur and microbial activity feeding thesulfur cycle(sulfide oxidationpossibly followed bybacterial sulfate reduction) have also to be taken into account. Strictly abiotic (i.e.inorganic) corrosion processes are generally slower under anoxic conditions than under oxic conditions, but the presence ofbacteriaandbiofilmscan aggravate the degradation conditions and causes unexpected problems. Critical infrastructures and metallic components with very long service life may be susceptible to pitting corrosion: for example the metallic canisters and overpacks aimed to contain vitrifiedhigh-level radioactive waste(HLW) andspent nuclear fueland to confine them in a water-tight enveloppe for several tenths of thousands years in deep geologic repositories.

Corrosion inhibitors

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Main article:Corrosion inhibitor

Different types ofcorrosion inhibitorexist. Among them, oxidizing species such aschromate(CrO2−
4) andnitrite(NO−
2) were the first used to re-establish the state of passivation in the protective oxide layer. In the specific case of steel, theFe2+cation being a relatively soluble species, it contributes to favor the dissolution of the oxide layer which so loses its passivity. To restore the passivity, the principle simply consists to prevent the dissolution of the oxide layer by converting the soluble divalentFe2+cation into the much less soluble trivalentFe3+cation. This approach is also at the basis of thechromate conversion coatingused topassivatesteel,aluminium,zinc,cadmium,copper,silver,titanium,magnesium,andtinalloys.[15]: p.1265 [16]

As hexavalent chromate is a known carcinogen, its aqueous effluents can no longer be freely discharged into the environment and its maximum concentration acceptable in water is very low.

Nitrite is also anoxidizing speciesand has been used as corrosion inhibitor since the 1950's.[17][18][19] Under the basic conditions prevailing inconcretepore water nitrite converts the relatively solubleFe2+ions into the much less solubleFe3+ions, and so protects the carbon-steelreinforcement barsby forming a new and denser layer of γ-Fe
2O
3as follows:

2 Fe2++ 2 NO−2+ 2 OH−→ Fe2O3+ 2 NO + H2O

Corrosion inhibitors, when present in sufficient amount, can provide protection against pitting. However, too low level of them can aggravate pitting by forming local anodes.

Engineering failures due to pitting corrosion

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A corrosion pit on the outside wall of apipelineat acoatingdefect before and afterabrasive blasting.
TheSilver Bridgecollapsed into theOhio Riveras a result ofstress corrosion cracking.

A single pit in a critical point can cause a great deal of damage. One example isthe explosion in Guadalajara,Mexico, on 22 April 1992, whengasolinefumes accumulated insewersdestroyed kilometers of streets. The vapors originated from a leak of gasoline through a single hole formed by corrosion between asteelgasoline pipe and azinc-plated water pipe.[20]

Firearms can also suffer from pitting, most notably in the bore of the barrel when corrosive ammunition is used and the barrel is not cleaned soon afterwards.[21]Deformities in theborecaused by pitting can greatly reduce the firearm's accuracy.[22]To reduce pitting in firearm bores, most modern firearms have a bore lined withchromium.[23]

Pitting corrosion can also help initiatestress corrosion cracking,as happened when a singleeyebaron theSilver BridgeinWest Virginia,United States, failed and killed 46 people on the bridge in December 1967.[24]

In laboratories, pitting corrosion may damage equipment, reducing its performance or longevity. Fume hoods are of particular concern, as the material constitution of their ductwork must suit the primary effluent(s) intended for exhaust.[25]If the chosen vent material is unsuitable for the primary effluent(s), consequent pitting corrosion will prevent the fume hood from effectively containing harmful airborne particles.[26]

See also

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References

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  1. ^Frankel, G. S. (1998-06-01)."Pitting corrosion of metals: A review of the critical factors".Journal of the Electrochemical Society.145(6): 2186–2198.Bibcode:1998JElS..145.2186F.doi:10.1149/1.1838615.hdl:1811/45442.ISSN1945-7111.Retrieved2022-02-12.
  2. ^abGuo, Peng; La Plante, Erika Callagon; Wang, Bu; Chen, Xin; Balonis, Magdalena; Bauchy, Mathieu; Sant, Gaurav (2018-05-22)."Direct observation of pitting corrosion evolutions on carbon steel surfaces at the nano-to-micro- scales".Scientific Reports.8(1): 7990.Bibcode:2018NatSR...8.7990G.doi:10.1038/s41598-018-26340-5.ISSN2045-2322.PMC5964123.PMID29789654.
  3. ^Macdonald, Digby D. (1992-12-01)."The point defect model for the passive state".Journal of the Electrochemical Society.139(12): 3434–3449.Bibcode:1992JElS..139.3434M.doi:10.1149/1.2069096.ISSN1945-7111.Retrieved2022-02-13.
  4. ^Macdonald, Digby D. (2011-01-15)."The history of the Point Defect Model for the passive state: A brief review of film growth aspects".Electrochimica Acta.Advances in Corrosion Science for Lifetime Prediction and Sustainability. Selection of papers from the 8th ISE Spring Meeting 2–5 May 2010, Columbus, OH, USA.56(4): 1761–1772.doi:10.1016/j.electacta.2010.11.005.ISSN0013-4686.Retrieved2022-02-13.
  5. ^Macdonald, Digby D. (2012-03-01)."Some personal adventures in passivity—A review of the point defect model for film growth".Russian Journal of Electrochemistry.48(3): 235–258.doi:10.1134/S1023193512030068.ISSN1608-3342.S2CID96662065.Retrieved2022-02-13.
  6. ^ASM Handbook, Volume 13, "Corrosion",ISBN0-87170-007-7,ASM International, 1987
  7. ^"Pitting corrosion".substech.com.21 July 2015.Retrieved4 December2020.
  8. ^Raja, Pandian Bothi; Ghoreishiamiri, Seyedmojtaba; Ismail, Mohammad (2015-06-01)."Natural corrosion inhibitors for steel reinforcement in concrete — A review".Surface Review and Letters.22(3): 1550040–1550608.Bibcode:2015SRL....2250040R.doi:10.1142/S0218625X15500407.ISSN0218-625X.Retrieved2022-02-13.
  9. ^Princeton.edu,pitcorrosion.
  10. ^Webb, Eric G.; Alkire, Richard C. (2002-06-01)."Pit initiation at single sulfide inclusions in stainless steel. I. Electrochemical microcell measurements".Journal of the Electrochemical Society.149(6): –272–B279.Bibcode:2002JElS..149B.272W.doi:10.1149/1.1474430.ISSN1945-7111.Retrieved2018-03-25.
  11. ^Webb, Eric G.; Alkire, Richard C. (2002-06-01)."Pit initiation at single sulfide inclusions in stainless steel. II. Detection of local pH, sulfide, and thiosulfate".Journal of the Electrochemical Society.149(6): –280–B285.Bibcode:2002JElS..149B.280W.doi:10.1149/1.1474431.ISSN1945-7111.Retrieved2018-03-25.
  12. ^Chi, Guangfang; Yi, Danqing; Liu, Huiqun (March–April 2020)."Effect of roughness on electrochemical and pitting corrosion of Ti-6Al-4V alloy in 12 wt.% HCl solution at 35 °C".Journal of Materials Research and Technology.9(2): 1162–1174.doi:10.1016/j.jmrt.2019.11.044.Pradhan et al. found that a larger available surface area can increase the corrosion rate, and the surface area increased with increasing surface roughness.
  13. ^Yu, Xiang; Al-Saadi, Saad; Zhao, Xiao-Ling; Rahman, R.K. Singh (October 2021)."Electrochemical Investigations of Steels in Seawater Sea Sand Concrete Environments".Materials.14(19): 5713.Bibcode:2021Mate...14.5713Y.doi:10.3390/ma14195713.PMC8510146.PMID34640111.It is known that mild steel rebar can form a protective passivation layer in the strong alkaline environment of concrete (when pH > 10). However, this layer can be destroyed by chloride ions and other harmful ions, diffusing from the ocean or industrial environment through the concrete matrix to the surface of the steel bars, causing rapid corrosion of the steel bars.
  14. ^Hesketh, J.; Dickinson, E. J. F.; Martin, M. L.; Hinds, G.; Turnbull, A. (2021-04-15)."Influence of H2S on the pitting corrosion of 316L stainless steel in oilfield brine ".Corrosion Science.182:109265.Bibcode:2021Corro.18209265H.doi:10.1016/j.corsci.2021.109265.ISSN0010-938X.PMC8276138.PMID34267394.
  15. ^K.H. Jürgen, Buschow, Robert W. Cahn, Merton C. Flemings, Bernhard Ilschner, Edward J. Kramer, and Subhash Mahajan (2001):Encyclopedia of Material – Science and Technology,Elsevier, Oxford, UK.
  16. ^Joseph H Osborne (2001): "Observations on chromate conversion coatings from a sol–gel perspective".Progress in Organic Coatings,volume 41, issue 4, pages 280-286.doi:10.1016/S0300-9440(01)00143-6
  17. ^Pourbaix, Marcel; Van Rysselberghe, Pierre (1950-09-01)."An electrochemical mechanism of corrosion inhibition by chromates, nitrites and other oxidants".Corrosion.6(9): 313–315.doi:10.5006/0010-9312-6.9.313.ISSN0010-9312.Retrieved2022-02-13.
  18. ^Pryor, M. J.; Cohen, M. (1953-05-01)."The inhibition of the corrosion of iron by some anodic inhibitors".Journal of the Electrochemical Society.100(5): 203.doi:10.1149/1.2781106.ISSN1945-7111.Retrieved2022-02-13.
  19. ^Hoar, T. P. (1958-02-01)."Nitrite inhibition of corrosion: some practical cases".Corrosion.14(2): 63–64.doi:10.5006/0010-9312-14.2.63.ISSN0010-9312.Retrieved2022-02-13.
  20. ^"Sewer explosion due to corrosion".Corrosion Doctors.
  21. ^"How Fast Corrosive Ammunition Ruins Guns".youtube.com.Backyard Ballistics. August 2, 2019. Archived fromthe originalon June 5, 2023.
  22. ^"Smyth Busters: Are Chrome-Lined Barrels Less Accurate?".youtube.com.Brownells.March 30, 2021. Archived fromthe originalon June 5, 2023.
  23. ^"Chrome Lining vs. Salt Bath Nitriding: Which Barrel Finish Is Better?".Criterion Barrels Inc. December 11, 2017. Archived fromthe originalon May 28, 2023.
  24. ^Silver bridge collapse,Corrosion Doctors, read May 13, 2016
  25. ^Kreitlein, Scott (February 8, 2022)."An Overview of Hazardous Exhaust Ductwork Construction and Material Selection".BHDP.RetrievedAugust 25,2023.
  26. ^Srinivas, P.N. (July 7, 2020)."Corrosion Is A Stealthy Hazard Dont Ignore It In Your Laboratory".Kewaunee.RetrievedAugust 25,2023.

Further reading

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Academic library – Free online college e-textbooks (2022)."Chloride-induced corrosion".Ebrary.Retrieved2022-02-12.

Hirao, Hiroshi; Yamada, Kazuo; Takahashi, Haruka; Zibara, Hassan (2005)."Chloride binding of cement estimated by binding isotherms of hydrates".Journal of Advanced Concrete Technology.3(1): 77–84.doi:10.3151/jact.3.77.eISSN1347-3913.ISSN1346-8014.Retrieved2022-02-19.

Galan, Isabel; Glasser, Fredrik P. (2015-02-01)."Chloride in cement".Advances in Cement Research.27(2): 63–97.doi:10.1680/adcr.13.00067.eISSN1751-7605.ISSN0951-7197.Retrieved2022-02-19.

Newman, Roger (2010-01-01)."Pitting corrosion of metals".The Electrochemical Society Interface.19(1): 33–38.Bibcode:2010ECSIn..19a..33N.doi:10.1149/2.F03101if.ISSN1944-8783.S2CID138876686.

Macdonald, Digby D.; Roberts, Bruce; Hyne, James B. (1978-01-01)."The corrosion of carbon steel by wet elemental sulphur".Corrosion Science.18(5): 411–425.Bibcode:1978Corro..18..411M.doi:10.1016/S0010-938X(78)80037-7.ISSN0010-938X.Retrieved2022-02-13.

Choudhary, Lokesh; Macdonald, Digby D.; Alfantazi, Akram (2015-06-01)."Role of thiosulfate in the corrosion of steels: A review".Corrosion.71(9): 1147–1168.doi:10.5006/1709.ISSN0010-9312.Retrieved2022-02-13.

Paik, C. H.; White, H. S.; Alkire, R. C. (2000-11-01)."Scanning electrochemical microscopy detection of dissolved sulfur species from inclusions in stainless steel".Journal of the Electrochemical Society.147(11): 4120–4124.Bibcode:2000JElS..147.4120P.doi:10.1149/1.1394028.eISSN1945-7111.ISSN0013-4651.Retrieved2018-03-25.

Newman, R. C.; Isaacs, H. S.; Alman, B. (1982-05-01)."Effects of sulfur compounds on the pitting behavior of type 304 stainless steel in near-neutral chloride solutions".Corrosion.38(5): 261–265.doi:10.5006/1.3577348.ISSN0010-9312.Retrieved2018-03-25.

Hesketh, J.; Dickinson, E. J. F.; Martin, M. L.; Hinds, G.; Turnbull, A. (2021-04-15)."Influence of H2S on the pitting corrosion of 316L stainless steel in oilfield brine ".Corrosion Science.182:109265.Bibcode:2021Corro.18209265H.doi:10.1016/j.corsci.2021.109265.ISSN0010-938X.PMC8276138.PMID34267394.

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