Rusting, resistance, crack, decomposition, exposed, moisture, decompose, treatment

1. … is oxidation of the iron atoms in solid solution.

2. Many metals corrode due to … in the air.

3. When corrosion is concentrated locally it forms a ….

4. Corrosion takes place on …surfaces.

5. The galvanic current causes the anode to ….

6. The heat … of metals is used to protect them against corrosion.

7. Passivation can increase the … to corrosion.

8. Corrosion is the chemical … of metals.

1. Agree or disagree with the following statements. Prove your reason. Use the expression: That’s right (wrong). As far as I know from the text...

1. The oxidation of metal parts in gasoline is called electrochemical corrosion.

2. The action of an electrolyte on metals causes corrosion.

3. Acids cannot conduct the electric current.

4. The conductive coupling is formed through the electrolyte between dissimilar metals.

5. All metals have the same electrolytic potential.

6. Rusty spots appear on the surface of copper when it corrodes.

7. Corrosion always extends uniformly on the surface of a metal part.

8. Inhibitors slow down the process of corrosion.

1. Translate the following sentences paying attention to the Infinitive. Find the examples of the Infinitive in the text:

1. What is the best method to increase the corrosion resistance of a material?

2. It is easy to hammer gold into shape because it is soft.

3. In the 15th century England continued to import iron and steel from the continent.

4. Alloying elements are added to protect metals against corrosion.

5. People combined copper and tin to make an alloy called bronze.

6. Iron is too reactive to exist in pure state in the ground.

7. In those days furnaces were not hot enough to melt iron completely.

8. To extract iron from the iron ore the ore was heated as much as possible.

9. The smiths knew how to introduce carbon when they wanted to produce steel.

10. To determine properties of a metal special machines are used.

11. Some metals have special properties; one of them is the capacity to conduct electric current.

12. Elasticity is the capacity of a material to resist deformation without permanent change of form.

9. Translate the text in writing. Use a dictionary. Find answers to the following questions:

1. What do we mean speaking about the corrosion of ceramic materials and polymers?

2. What happens to corrosion products of gold and platinum?

3. What do you know about the corrosion of metals with slow reaction kinetics?

Corrosion is deterioration of useful properties in a material due to reactions with its environment. Formation of an oxide of iron due to oxidation of the iron atoms in solid solution is a well-known example of electrochemical corrosion, commonly known as rusting. This type of damage usually affects metallic materials and typically produces oxide(s) and/or salt(s) of the original metal. Corrosion also includes the dissolution of ceramic materials and can refer to discolouration and weakening of polymers by the sun's ultraviolet light. In other words, corrosion is the wearing-away of metals due to a chemical reaction.

Some metals are more resistant to corrosion than others, either due to the fundamental nature of the electrochemical processes involved or due to the details of how reaction products form. Many structural alloys corrode merely from exposure to moisture in the air, but the process can be strongly affected by exposure to certain substances. The materials most resistant to corrosion are those for which corrosion is thermodynamically unfavourable. Corrosion products of gold and platinum tend to decompose spontaneously into pure metal, that is why these elements can be found in metallic form in the ground.

Some metals have naturally slow reaction kinetics, even though their corrosion is thermodynamically favourable. These include such metals as zinc, magnesium and cadmium. While corrosion of these metals is continuous and ongoing, it happens at an acceptably slow rate. An extreme example is graphite, which releases large amounts of energy upon oxidation but has such slow kinetics that it is effectively immune to electrochemical corrosion under normal conditions.

1. Look through the text and answer the questions:

1. When does galvanic corrosion occur?

2. In what cases is galvanic corrosion of interest?

Galvanic corrosion occurs when two different metals electrically contact each other and are immersed in an electrolyte. In order for galvanic corrosion to occur, an electrically conductive path and an ionically conductive path are necessary. This gives a galvanic couple where the more active metal corrodes at an accelerated rate and the more noble metal corrodes at a slow rate. When immersed, neither metal would normally corrode as quickly without the electrically conductive connection (usually via a wire or direct contact). Galvanic corrosion is often utilized in sacrificial anodes. For example, zinc is often used as a sacrificial anode for steel structures, such as pipelines or docked naval ships. Galvanic corrosion is of major interest to the marine industry and also anywhere water can contact pipes or metal structures.

Unit 7

1. Memorize the following words:

exter­nal forces load invariable magnitude strain failure tension compression torsion bend­ing shear fatigue original permanent suffer stress fracture creep stretch exceed rupture eliminate be subjected

внешние силы нагрузка неизменяемый величина деформация повреждение растяжение сжатие кручение изгиб срез усталость первоначальный постоянный пострадать напряжение образовывать трещины ползучесть растягивать превышать разрушаться устранять подвергаться

зовнішні сили навантаження незмінний, постійний величина деформація пошкодження розтягнення стискування кручення вигин зріз втома первинний постійний постраждати напруга утворювати тріщини повзучість розтягувати перевищувати руйнуватися усувати зазнавати

1. Practise the reading of the following words:

External, failure, cause, invariable, fatigue, shear, tensile, technology, determine, mechanical, judge, behaviour, static, dynamic, instantaneously, cyclic, alternating, torsion, elastic, original, fracture, decrease, to subject, simultaneously, vibration, exceed, localized, rupture.