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.
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.
Unit 4
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.
4 . Read and translate the text. Summarize it in Russian.
Atmospheric corrosion accounts for more failures on both a tonnage 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.
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