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Файл:Metal corrosion. Electroplating (Защита металлов от коррозии. Гальванотехника). Учебно-методическое пособие
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6. Work in pairs. Translate the following text from English into
Russian.
MIC is not caused by a single microbe, but is attributed to many
different microbes. These are often categorized by common characteristics
such as by-products (i.e., sludge producing) or compounds they effect (i.e.
sulfur oxidizing). In a general sense, they all fall into one of two groups
based upon their oxygen requirements; one being aerobic (requires oxygen)
such as sulfur oxidizing bacteria, and the other being anaerobic, (requires
little or no oxygen), such as sulfate reducing bacteria.
General corrosion affects the entire surface or at least the wetted
surface. MIC, on the other hand, is very localized. It creates a nodule and a
pit beneath the nodule. There can be only a few nodules or there can be
many. Within these nodules microbes rarely work alone but operate as a
mixed community of differing types and groups. The different microbes
perform different functions within the community. This interaction allows a
community to thrive in environments that are actually hostile to some of its
members. For example, in an aerobic environment, anaerobic bacteria are
generally inhibited or killed. But within a community the aerobic bacteria
reside in the outer layer of the nodule consuming the oxygen in the water as
it penetrates the nodule. Thus, the inner portion of the nodule experiences a
reduced oxygen level allowing anaerobic bacteria to thrive.
7. Read the text. What is its main idea?
Почва является вместилищем необычайно обильной и
разнообразной микрофлоры, представленной многочисленными
группами бактерий, плесневыми грибками, дрожжевыми организмами
и т. п.
Количество разнообразных бактерий, приходящееся на 1 грамм
почвы, достигает сотен миллионов, а иногда и десятков миллиардов.
Основная масса микроорганизмов встречается в верхних горизонтах
почвы, однако и в подпочвенных слоях они содержатся в
значительном количестве. В некоторых случаях эти организмы могут
вызывать интенсивную коррозию, получившую наименование
микробиологической коррозии.
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Действие микроорганизмов сводится или к непосредственному
влиянию на скорость анодной и катодной реакций, или к созданию
коррозийной среды.
Наибольшее значение и распространение в почвенных
условиях имеет анаэробная коррозия.
Коррозионный процесс в анаэробных условиях заключается в
том, что благодаря жизнедеятельности микроорганизмов в среде,
окружающей подземное сооружение, сульфаты восстанавливаются и
преобразуются в сероводород. Последний взаимодействует с железом,
образуя сернистое железо. Освободившийся при восстановлении
сульфатов кислород обеспечивает деполяризацию катода, на котором
должен накапливаться водород в связи с растворением железа. Таким
образом, через катодную деполяризацию бактериальный процесс
стимулирует развитие коррозии.
(From www.groont.com)
8. Work in pairs. Interpret the following passage sentence by
sentence.
Corrosion resulting from the attachment and activities of
microorganisms on metal surfaces is referred to as microbiologically
influenced corrosion (MIC) or biocorrosion. It occurs in diverse
environments and is not limited to aqueous submerged conditions, but also
takes place in humid atmospheres. It is an electrochemical process in which
the participation of microorganisms is able to initiate, facilitate, or
accelerate the corrosion reactions without changing the process’s
electrochemical nature. MIC is a result of interactions that are often
synergistic between the metal surface, abiotic corrosion products, and
microbial cells and their metabolites. The latter includes organic and
inorganic acids and volatile compounds, such as ammonia and hydrogen
sulfide. Microbiologically mediated reactions do not result in a unique type
of corrosion, but they can induce localized corrosion, change the rate of
corrosion and also inhibit corrosion.
Most MIC studies have focused on bacterial involvement; however,
under aerobic conditions, other single-celled organisms, such as fungi, yeast
and diatoms, can influence corrosion. The predominant types of bacteria
associated with MIC are sulfate-reducing bacteria (SRB), sulfur-oxidizing
bacteria, iron-oxidizing/reducing bacteria, manganese oxidizing bacteria,
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and bacteria secreting organic acids and slime. These organisms coexist
within a biofilm matrix on metal surfaces, functioning as a consortium in a
complex and coordinated manner. The various mechanisms of biocorrosion
reflect the variety of physiological activities carried out by these different
types of microorganisms when they coexist in biofilms. Despite decades of
study on MIC, it is still not known with certainty how many species of
microorganisms contribute to corrosion, and researchers continue to report
on the formation of biofilms by an ever-widening range of microbial
species.
9. Give English equivalents to the following word combinations
and learn them by heart:
деятельность микроорганизмов
различные среды
электрохимический процесс
органическая кислота
металлическая поверхность
сероокисляющие бактерии
образование биопленок
микробные виды
аэробные условия
синтетическая коррозия
10. Give Russian equivalents to the following word
combinations and learn them by heart:
inhibit corrosion
entire surface
organic acid
hydrogen sulfide
manganese oxidizing bacteria
predominant type
biofilm matrix
physiological activities
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11. Translate the following sentences into Russian.
1. Some bacteria can directly reduce metal atoms to ions.
2. Hydrogen ions are produced, along with hydroxyl ions, by the
breakdown of water, and the electrons to form atomic hydrogen from the
hydrogen ion are produced by the oxidation of atomic iron.
3. The source of electrons is the oxidation of the metal while the
electron sink is reduction of hydrogen ions.
4. MIC has been observed as one of the major causes of
underground pipeline corrosion.
5. Sulphate reducing bacteria (SRB) have been reported to be
responsible for extensive corrosion in hydrocarbon industry.
6. There are other types of corrosion-enhancing bacteria such as
iron-reducing bacteria, iron-oxidizing bacteria, nitrifying bacteria,
methanogenic bacteria and so on.
7. New technologies that may assist mitigation are basically based
on using certain biological technologies (such as use of “good” bacteria
against corrosion-related bacteria).
8. Almost all known engineering materials (from carbon steel to
stainless and duplex stainless steels and also non-ferrous metals such as
copper alloys and non-metals such as some polymers and concrete) are
susceptible to MIC.
9. Gas velocity and temperature in the pipeline play a significant
role in determining if and where corrosion damage may occur.
10. Accelerated Low Water Corrosion (ALWC) is a particularly
aggressive form of MIC that affects steel piles in seawater near the low
water tide mark.
12. Translate the following sentences into English.
1. Биокоррозия (от греч. bios – жизнь и позднелат. corrosio –
разъедание) – разрушение конструкционных материалов и
противокоррозионных защитных покрытий под действием
присутствующих в среде микроорганизмов (бактерий, грибов,
водорослей, дрожжей).
2. Биокоррозия подразделяется на бактериальную и
микологическую.
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3. Наиболее опасными микроорганизмами являются бактерии,
так как они быстро размножаются и легко приспосабливаются к
условиям окружающей среды.
4. Благоприятными условиями для развития плесени является
температура 25–35°С и повышенная влажность воздуха, превышающая 75%.
5. В процессе жизнедеятельности микроорганизмов образуются продукты обмена веществ, повышающие коррозионную
активность среды (минеральные и органические кислоты, щелочи,
пероксиды и др.)
6. Алюминиевые сплавы – одни из наиболее устойчивых к
коррозии конструкционных материалов. Однако и они подвержены
биокоррозии.
7. Биокоррозия металлов может быть вызвана действием
сульфатовосстанавливающих бактерий.
8. Предполагается, что бактерии замещают и поглощают
водород, образуя очаги, на анодных участках которых происходит
усиленная коррозия металла.
9. Анаэробная коррозия приносит огромный ущерб нефтегазовой промышленности (трубопроводы, емкости для хранения и
транспорта нефтепродуктов).
10. Для объяснения процесса коррозии в анаэробных условиях
Кюр и Флюгт предложили следующие реакции: анодную, катодную,
катодную деполяризацию при участии бактерий, образование
продуктов коррозии.
13. Translate the following word combinations.
Cульфатовосстанавливающие бактерии – stainless steel –
скорость потока газов – hydrogen sulfide – органические кислоты –
suitable environments – аэробные условия – proliferate – медные сплавы
– high humidity – полимеры – structural materials – минеральные
кислоты – single-celled organisms – катодная деполяризация – formation
of biofilms.
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14. Give the definitions of the words and word combinations.
1. Microbe is … .
2. Sludge is … .
3. Microbial flora is… .
4. Velocity is … .
5. Synergetics is … .
15. Give the example(s) of the microbial corrosion.
16. Answer the following questions using texts from Unit 3.
1. What does microbial corrosion mean?
2. What types of microbiological corrosion do you know?
3. What are the predominant types of bacteria associated with
microbial corrosion?
4. Describe anaerobic corrosion.
17. Summarize the general ideas developed in all the texts of the
Unit 3.
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Unit 4
А
В
ATMOSPHERIC CORROSION
1. Read the international words, guess their meanings and give
the Russian equivalents.
Temperature, atmospheric, industry, salt, characterize, system,
chloride, aggressive, factor, material, sulphide, synergistic, parameter,
conventional, function, manner, transferable.
2. Read and translate the following verbs.
To classify, to attack, to expose, to increase, to promote, to contain,
to contribute, to influence, to suffer, to comprise, to lead to, to correlate, to
restrict, to find, to transfer, to know.
3. Match the English phrases from column A with the Russian
phrases in column B.
1) atmospheric corrosion
2) durability of materials
3) sulphur compounds
4) atmospheric contaminant
5) wind velocity
6) airborne particles
7) synergistic interaction
8) definite solution
9) solar radiation
10) atmospheric pollutants
11) correlation equation
12) predictive capability
4. Read and translate the text. Summarize it in Russian.
Atmospheric corrosion accounts for more failures on both a tonnage
a) частицы аэрозоля
b) прогностическая способность
c) солнечное излучение
d) прочность материалов
e) атмосферный загрязнитель
f) корреляционная уравнение
g) соединения серы
h) атмосферная коррозия
i) скорость ветра
j) синергетическое
взаимодействие
k) атмосферные загрязнители
l) определенное решение
27
basis and cost basis than any other type of environmental corrosion.
Tremendous amounts of steel in automobiles, bridges ad buildings are
exposed to the atmosphere and attacked by oxygen and water. The
corrosion severity is increased when salt, sulfur compounds and other
atmospheric contaminants are present. Atmospheric environments can be
classified as: industrial, marine, rural, indoor.
Industrial environments contain sulfur compounds, nitrogen
compounds, and other acidic agents that can promote the corrosion of
metals. In addition, industrial environments contain a heavier loading of
airborne particles, which also contribute to corrosion. Marine environments
are characterized by the presence of chloride, an ion that is particularly
detrimental to the corrosion behavior of many metals systems. Rural
environments are the least corrosive of the atmospheric environments,
being characterized by lower levels of acidic compounds and other
aggressive species.
The principal factors influencing atmospheric corrosion for a given
metal are moisture, temperature and the presence of contaminants in the
environment. (From www.researchgate.net)
5. Read the text again. Decide whether the following
statements are true or false.
1. Urban environments are the least corrosive of the atmospheric
environments.
2. The main factors influencing atmospheric corrosion for a given
metal are pressure, velocity and temperature and the presence of
contaminants in the environment.
3. Marine environments are characterized by the presence of copper
and sulphur.
4. Atmospheric environments can be classified as: urban, marine
and rural.
6. Work in pairs. Translate the following sentences from
English into Russian.
The term “atmospheric corrosion” comprises the attack on metal
exposed to the air as opposed to metal immersed in a liquid. Atmospheric
corrosion is the most prevalent type of corrosion for common metals.
28
Atmospheric corrosion is a subject of global concern because of its
importance to the service life of equipment and durability of the structural
materials. While there is a general agreement on the possible types of
parameters that may lead to corrosion, these studies suffer severely from the
lack of generality in the sense that their predictive capability is extremely
poor. Conventional atmospheric parameters that may lead to metal
corrosion comprise of weathering factors such as temperature, moisture,
rainfall, solar radiation, wind velocity, etc. Air pollutants such as sulphur
dioxide, hydrogen sulphide, oxides of nitrogen, chlorides have also been
found to contribute to atmospheric corrosion. The complexity and diverse
nature of the atmospheric pollutants make the prediction of the atmospheric
corrosion difficult. The synergistic interaction of the variables must also be
considered in the model for arriving at a definite solution. A direct approach
to the problem is to measure the observed corrosion rates and the
participating atmospheric parameters and correlate them. The correlation
equations, thus derived, are known as damage functions and they have been
found to be extremely useful, though in a restricted manner, as the results
are not easily transferable from one place to another.
7. Read the text. What is its main idea?
Особенностью атмосферной коррозии является возможность
свободного подхода кислорода к корродирующей поверхности. Это
обусловлено малой толщиной пленки и за счет конвекции
перемешивания электролита. Именно поэтому даже в подкисленных
электролитах атмосферная коррозия протекает с кислородной
деполяризацией.
Также из-за тонкого слоя влаги на поверхности
корродирующего металла анодный процесс идет с затруднением, а
протекание катодного, наоборот, облегчается.
При работе гальванопар (galvanic couple) небольшая толщина
пленки влаги тоже играет свою роль - увеличивается омическое
сопротивление электролита.
Атмосферная коррозия сплавов, в основу которых входит
железо (например, сталь), протекает с анодно-катодно-омическим
контролем. Но в зависимости от некоторых условий (толщина,
электропроводность пленки влаги, ее состав, природа металла)
анодно-катодно-омический контроль может переходить в
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преимущественно анодный, преимущественно катодный или
омический. (From www.okorrozii.com)
8. Work in pairs. Interpret the following passage sentence by
sentence.
The most common characteristic of metallic atmospheric corrosion
is the localized character of its nucleation. Preferential nucleation sites
depend on the metal structure and are associated to the presence of different
phases or environmental pollutants on discrete areas of the metallic surface.
In the case of carbon steel, nucleation starts with the formation of small
protuberances of corrosion products at isolated points on the metallic
surface, followed by the formation of a large number of corrosion product
nuclei that can cover the entire surface after relatively short exposure times.
9. Give English equivalents to the following word combinations
and learn them by heart:
скорость коррозии
коррозийный процесс
сырость внешних конструкций
коррозия в металлах
химическая активность углеродной стали
атмосферная коррозия меди
агрессивные среды
анодный процесс
прогнозируемость атмосферной коррозии
10. Give Russian equivalents to the following word
combinations and learn them by heart:
galvanic couple
ohmic control
cathodic process
electric conductivity
atmospheric pollution
fossil fuels
combustion products
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