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Файл:Metal corrosion. Electroplating (Защита металлов от коррозии. Гальванотехника). Учебно-методическое пособие
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Unit 6
А
В
FORMS OF CORROSION
1. Read the international words, guess their meanings and give
the Russian equivalents.
Immunity, mechanism, concentration, structurally, mixture, crystal,
atom, stress, turbulent, collapse, regular, nonmetal, component, agent,
dominate, organic, abrasion, hydrodynamics, cracking.
2. Read and translate the following verbs.
To validate, to migrate, to encounter, to induce, to create,
to produce, to collapse, to move, to expose, to mark, to exceed, to elevate,
to carburize, to embrittle, to leave.
3. Match the English phrases from column A with the Russian
phrases in column B.
1) relative motion
2) test measurement
3) basic mechanism
4) concentration cell corrosion
5) cavitation сorrosion
6) metal crystals
7) grain boundaries
8) hydrogen embrittlement
9) loss of ductility
10) low pressure
11) result in abrasion
12) corrosion cracking
a) концентрационная
коррозия
b) кавитационная коррозия
c) межзеренная граница
d) вязкость металла
e) водородная хрупкость
f) низкое давление
g) относительное движение
h) приводить к истиранию
i) основной механизм
j) коррозийное
растрескивание
k) контрольное измерение
l) металлические кристаллы
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4. Read and translate the text. Summarize it in Russian.
There are various forms of corrosion:
1. Immunity. The first form of corrosion described is the lack of
attack, or immunity. This can result from the action of two basic
mechanism. Corrosion test measurements that are used to measure very low
corrosion rates must be used to validate that corrosion activity is completely
absent.
2. Concentration Cell Corrosion. As mentioned above, a difference
in environment between sites on a single metal can also result in increased
electrochemical activity.
3. Dealloying. Most of the commonly used metallic material are
alloys formed from mixing two or more metals. Pure metals are usually too
soft and weak to be used structurally. In dealloying, corrosion selectively
attacks one or more constituent of the alloy mixture.
4. Intergranular Corrosion. Just as most engineering metals are
mixtures of one or more metals, they consist of large numbers of individual
metal crystals called grains that are joined together at their surfaces or grain
boundaries.
5. Hydrogen Embrittlement. Hydrogen can enter most metals. Due
to the small size of the hydrogen atom, it can migrate through the metal
structure and cause a loss of ductility similar to that experienced in stress
corrosion cracking.
6. Erosion Corrosion. When water flows over a metal surface at
high velocity, corrosion can be greatly increased over that encountered at
low flow velocities.
7. Cavitation Corrosion. Under high velocity flow conditions,
particularly when the flow is turbulent, areas of high and low pressure will
be induced. In areas of low pressure, gas and vapor bubbles will be
produced. When these bubbles move to an area of higher pressure, they
collapse and their implosion creates a pressure wave that can remove
protective films and cause increased corrosion.
8. Fretting Corrosion. When surfaces move in relation to each
other, this relative motion can result in abrasion. This abrasion can increase
the attack at these fraying surfaces. (From
corrosion.ksc.nasa.gov/corr_forms.htm)
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5. Read the text again. Decide whether the following statements
are true or false.
1. Corrosion test measurements that are used to measure very high
corrosion rates must be used to validate that corrosion activity is partially
absent.
2. Most of the commonly used non-metallic material are alloys
formed from mixing ten or more metals.
3. Hydrogen can react with most metals.
6. Read the text. What is its main idea?
Immunity can result from two basic mechanisms. In the first case,
the energy content of the metal is lower (more stable) than any of the
corrosion products that could possibly form. Such metals are commonly
found in nature as metals that indicates the stability of the metallic state for
these elements.
Corrosion of such metals where an increase of energy is required
will not take place naturally just as a ball will not roll uphill unless pushed.
In the second case, there is an energy tendency for the metal to
suffer corrosion, but corrosion activity is prevented by the presence of a
highly stable passive film. Not only must this film be stable in the
environment, but it must be able to repair itself by reaction with the
environment if it is damaged.
Gold and platinum are examples of metals that are normally
immune in a wide variety of environments due to the low energy content of
their metallic state. Titanium and some highly alloyed materials, such as the
complex nickel - chromium - molybdenum alloy Hastelloy C-276, have an
extremely stable passive film that will repair itself when damaged.
A metal that is immune to corrosion in a given environment will not
show any change due to corrosion after exposure. Metals that do not suffer
corrosion are unchanged by exposure to their environment. Their strength,
weight, size, shape, and surface finish are unaffected by exposure. To
measure very low rates of corrosion, weight loss and other material
property measurements may not be sufficiently sensitive. In these cases, the
metal is exposed to a small quantity of the electrolyte and the electrolyte is
analyzed for the presence of metal atoms from the corrosion process.
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7. Work in pairs. Translate the following text from English into
Russian.
Различные сплавы, в частности алюминиевые, увеличивают
свою твердость и прочность при старении; процесс ускоряют,
подвергая сплав термообработке. При этом образуются
субмикроскопические частицы, которые располагаются вдоль
пограничных слоев микрокристаллов (в межкристаллитном
пространстве) сплава. В определенных условиях область,
непосредственно примыкающая к границе, становится анодом по
отношению к внутренней части кристалла, и в коррозионной среде
границы между кристаллитами будут преимущественно подвержены
коррозии, причем коррозионные трещины глубоко внедряются в
структуру металла. Эта «структурная коррозия» серьезно влияет на
механические свойства. Ее можно предотвратить либо с помощью
правильно подобранных режимов термообработки, либо защитой
металла непроницаемым для коррозии покрытием. Плакирование –
холодное покрытие одного металла другим: высокопрочный сплав
прокатывается между тонкими полосками чистого алюминия и
уплотняется. Металл, входящий в подобную композицию, становится
коррозионностойким, при этом само покрытие слабо сказывается на
механических свойствах. (From www.dic.academic.ru)
8. Work in pairs. Interpret the following passage sentence by
sentence.
Intergranular corrosion (IGC), also known as intergranular attack
(IGA), is a form of corrosion where the boundaries of crystallites of the
material are more susceptible to corrosion than their insides.
This situation can happen in otherwise corrosion-resistant alloys,
when the grain boundaries are depleted, known as grain boundary
depletion, of the corrosion-inhibiting elements such as chromium by some
mechanism. In nickel alloys and austenitic stainless steels, where chromium
is added for corrosion resistance, the mechanism involved is precipitation of
chromium carbide at the grain boundaries, resulting in the formation
chromium-depleted zones adjacent to the grain boundaries (this process is
called sensitization). Around 12% chromium is minimally required to
ensure passivation, mechanism by which an ultra thin invisible film, known
44
as passive film, forms on the surface of stainless steels. This passive film
protects the metal from corrosive environments. The self-healing property
of the passive film make the steel stainless. Selective leaching often involve
grain boundary depletion mechanisms.
9. Give English equivalents to the following word combinations
and learn them by heart:
область высокого давления
водородная хрупкость
свойства материала
межзеренные границы
потеря веса
низкая скорость
электрохимическая активность
покрытие поверхности
10. Give Russian equivalents to the following word
combinations and learn them by heart:
submicroscopic particles
heat-treat
metal protection
extrahigh tensile alloy
stress corrosion crack
impervious coatings
low alloy steel
spot welding
11. Translate the following sentences into Russian.
1. There are several forms of corrosion, also referred to as modes or
mechanisms of corrosion.
2. Many aluminum base alloys are susceptible to intergranular
corrosion on account of either phases anodic to aluminum being present
along grain boundaries.
3. Corrosion fatigue is a special case of stress corrosion caused by
the combined effects of cyclic stress and corrosion.
45
4. No metal is immune from some reduction of its resistance to
cyclic stressing if the metal is in a corrosive environment.
5. Concrete is a widely-used structural material that is frequently
reinforced with carbon steel reinforcing rods, post-tensioning cable or
prestressing wires.
6. Erosion corrosion is the acceleration or increase in rate of
deterioration or attack on a metal because of relative movement between a
corrosive fluid and the metal surface.
7. There are several forms of corrosion, also referred to as modes or
mechanisms of corrosion.
8. Popular classification of forms of corrosion has been made by
Fontana, on the basis of the visual appearance of corrosion damage.
9. The Chromium available to form the passive layer is effectively
reduced and corrosion can occur.
10. Both pitting and crevice corrosion can lead to stress corrosion
cracking (SCC) under certain conditions.
12. Translate the following sentences into English.
1. При малой коррозионной потере массы разрушение
материала может проникать на большую глубину и сопровождаться
снижением прочности и пластичности материала.
2. Межкристаллитной коррозии подвержены многие сплавы на
основе железа, а также никелевые, алюминиевые и другие сплавы,
имеющие, как правило, неоднородную структуру.
3. В сильноокислительных средах развитие межкристаллитной
коррозии обусловлено избирательным растворением насыщенных фаз.
4. Язвенная коррозия, как правило, протекает на поверхности
активно растворяющихся металлов и по характеру своего развития
напоминает питтинговую коррозию.
5. Стойкость углеродистых и низколегированных сталей
против язвенной коррозии в значительной степени зависит от их
структурных и структурно-фазовых составляющих.
6. Резкое снижение стойкости сталей против язвенной
коррозии происходит при выделении в их структуре сульфидных
неметаллических включений на основе кальция.
7. Местная коррозия развивается на отдельных участках
поверхности и проявляется в виде пятен и язв.
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8. Она протекает быстрее, чем общая, и опасна тем, что может
привести к потере прочности отдельных деталей.
9. Одной из разновидностей местной коррозии является
контактная коррозия, возникающая, например, в местах соединения
деталей точечной сваркой, болтами или заклепками.
10. Наиболее распространенным способом защиты автомобиля
от коррозии является окраска кузова и других деталей
лакокрасочными материалами.
13. Translate the following word combinations.
Местная коррозия – intergranular corrosion – неоднородная
структура – weight loss – язвенная коррозия – self-healing property –
снижение скорости – interlayer – коррозийностойкий металл –
cavitation corrosion – сильноокислительные среды – selective leaching –
стойкость стали – abrasion – коррозийное растрескивание –
precipitation of chromium carbide.
14. Give the definitions of the words and word combinations.
1. Cracking is … .
2. Thermal treatment is … .
3. Combustion is … .
4. Conductor is … .
5. Energy is … .
15. Give the example(s) of the cavitation corrosion.
16. Answer the following questions using texts from Unit 6.
1. Enumerate forms of corrosion and give their definitions.
2. Give an example of immunity corrosion.
3. How does intergranular corrosion appear?
17. Summarize the general ideas developed in all the texts of the
Unit 6.
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Unit 7
А
В
CORROSION PROBLEMS
1. Read the international words, guess their meanings and give
the Russian equivalents.
Method, application, locate, problem, diagnose, effectively,
identify, visual, inspector, specialize, portion, problematic, chromium,
molybdenum, affect, nickel, titanium, per cent
2. Read and translate the following verbs.
To solve, to detect, to inspect, to experience, to specialize,
to require, to insulate, to reduce, to contaminate, to target, to exhaust, to
manufacture, to transport, to exchange.
3. Match the English phrases from column A with the Russian
phrases in column B.
1) maintenance inspection
2) trapped water
3) protective coatings
4) cathodic protection
5) corrosion expenditure
6) petrochemical industry
7) electronic equipment
8) refining process
9) significant improvement
10) contamination of
chemicals
11) fatal to human
12) remote monitoring
a) загрязнение химикатами
b) процесс очистки
c) электронное оборудование
d) реликтовая вода
e) значительное
усовершенствование
f) защитные покрытия
g) смертельно для человека
h) технический осмотр
i) дистанционный мониторинг
j) катодная защита
k) нефтехимическое
производство
l) издержки коррозии
48
4. Read and translate the text. Summarize it in Russian.
In order to establish proper methods for the application of corrosion
control to existing structures and equipment, it is necessary to locate the
sites where corrosion is occurring or likely to occur and to establish the
causes of corrosion. Only after the corrosion problem is located and
diagnosed can it be effectively solved.
Maintenance control inspections are the primary means for
identifying actual or potential corrosion problems. Visual observations are
the primary means of performing maintenance control inspections.
Inspectors must be familiar not only with the structures and equipment that
they are inspecting but with the corrosion problems experienced in those
structures and equipment and with the forms of corrosion that occur. It is
important that the maintenance control inspector be able to properly
identify and describe the type of corrosion that is detected. Through an
understanding of the basics of corrosion control, the maintenance control
inspector can also identify factors, such as trapped water or deteriorated
protective coatings that will eventually lead to corrosion damage.
Specialized inspections require skills or equipment over and above
that required for maintenance control inspections. Inspection of the
underwater portions of waterfront structures, and some of the inspections
performed on cathodic protection systems are considered specialized
inspections.
(From http://www.bushman.cc/pdf/corrosion_theory.pdf)
5. Read the text again. Decide whether the following statements
are true or false.
1. Tactile observations are the primary means of performing
maintenance control inspections.
2. It is difficult to determine factors leading to corrosion damage by
the maintenance control inspections.
3. Specialized inspections require counting skills or certified
equipment.
6. Read the text. What is its main idea?
С тех самых пор, когда у людей появились изделия из металла,
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появилась проблема коррозии, которая стала «главным врагом» всего
железного. Ее изучают ученые всех стран (в основном в области
машиностроения), чтобы создать универсальное средство защиты. И в
этом направлении появились определённые успехи.
Многим известно, что коррозия, - это когда на металлической
части автомобиля появляется ржавчина, которая со временем
разрушает всю поверхность, а потом и саму деталь, если вовремя не
предпринять определенные меры.
Если посмотреть на коррозию с точки зрения химии, то это
сложный химический процесс, который протекает только в
присутствии воды и кислорода. А так как они присутствуют в
атмосфере Земли в избытке, то полностью автомобиль от коррозии
избавить в обычных условиях невозможно. Можно решить вопрос
лишь замедления процесса коррозии с помощью специальных
химических антикоррозийных материалов.
(From www.dekorativnaya-metallicheskaya-kovka.ru)
7. Work in pairs. Translate the following text from English into
Russian.
Some pipelines deteriorate slowly, and in certain cases pipeline life
has been reliably targeted at 70 years or more. Other pipelines have been
built which have exhausted their useful life after 1 year of operation. Apart
from the quality of the construction, coatings, CP systems etc, the factors
which affect pipeline life include nature of the product, nature of the
external environment, operating conditions and quality of maintenance.
The corrosion-related cost to the transmission pipeline industry is
approximately $5.4 to $8.6 billion annually. This can be divided into the
cost of failures, capital, and operations and maintenance at 10, 38, and 52
percent, respectively. Although data management, system quantification
through the use of global positioning surveys, remote monitoring, and
electronic equipment developments have provided significant improvement
in several areas of pipeline corrosion maintenance, there have been few
basic changes in the approach to the management of corrosion on pipelines
until recently.
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