Unit 5
GALVANIC CORROSION
1 . Read the international words, guess their meanings and give the Russian equivalents.
Accelerate, electrical, contact, conductive, galvanic, phenomenon, attack, uniform, nature, service, condition, film, erosion, limit, effective, action, anode, cathode, test, region.
2 . Read and translate the following verbs.
To depend on, to remove, to insulate, to reverse, to separate, to utilize, to try, to perform, to allow, to expect, to indicate, to generate, to apply, to diminish, to connect, to match.
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.
Accelerated corrosion which can occur when dissimilar metals are in electrical contact in the presence of an electrolyte (i.e. conductive solution). An example of this corrosion phenomenon is increased rate of corrosion of steel in seawater when in contact with copper alloys. Galvanic attack can be uniform in nature or localized at the junction between the alloys depending on service conditions. Galvanic corrosion can be particularly severe under conditions where protective corrosion films do not form or where they are removed by conditions of erosion corrosion.
Prevention or Remedial Action: selection of alloys which are similar in electrochemical behavior and/or alloy content; area ratio of more actively corroding material (anode) should be large relative to the more inert material(cathode); use coatings to limit cathode area; insulate dissimilar metals; use of effective inhibitor.
(From www.galvanic-corrosion.com).
5 . Read the text again. Decide whether the following statements are true or false.
1. Accelerated corrosion phenomenon is decreased rate of corrosion of steel in seawater when in contact with copper alloys.
2. Galvanic corrosion which can occur when dissimilar metals are in chemical contact in the presence of an electrolyte.
3. Galvanic corrosion can be mainly partial under conditions where protective corrosion films form or where they are removed by conditions of erosion corrosion.
6 . Work in pairs. Translate the following sentences from English into Russian.
Many people utilized the standard galvanic series of materials in seawater to predict service performance relative to galvanic corrosion. In fact, this galvanic series is specific to only seawater at near ambient conditions. Other factors such as temperature and the presence of other chemical species can greatly affect the rank ordering of materials.
Конец ознакомительного фрагмента.