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FERROUS AND NON-FERROUS METALS



All metals, with the exception of mercury (ртуть), are hard- and fire-resistant. The common properties of metals being hardness and high fire-resistance, they are widely used in modern construction.

Metals are divided into two main groups: ferrous and non-ferrous. Iron, steel and their various alloys belong to the group of ferrous metals, while the main component of non-ferrous metals is not iron.

All metals have some common properties: they can be pulled, forged, and melted. They are also good conductors of electricity.

Ferrous metals are commonly used for construction of supporting members. Steel and other ferrous metals serve as reinforcement in ferro­concrete constructions.

As to non-ferrous metals, their advantage is their being light. They are also good conductors of electricity, copper being the best one. Metals possess high resistance.

2. What are the properties of metals?

3. What metals are called ferrous and what metals are non-ferrous?

4. What are the properties of ferrous metals?

5. Where are they used in construction?

6. What are the properties of non-ferrous metals?

TEXT 6.

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ALUMINUM. ALUMINA

Aluminum is a considerably new structural material. For a long peri­od it was considered to be rather expensive since its production required the use of electric power. Because of its relatively high cost, aluminum was not very popular as a construction material till the middle of the twentieth century. But now the situation is absolutely different.

Aluminum and aluminum-based alloys are extremely popular and are widely used in various forms for construction purposes.

The advantages of aluminum, compared with other popular metals, are its high strength combined with lightness. High-purity aluminum (about 99% pure) is soft and ductile but its great disadvantage is that it is not strong enough. At the same time it has high corrosion resistance and is used in construction of buildings as bright foil for heat insulation, roofing, exterior and interior architectural ornamentation.

And what about aluminum alloys? They are much more advantageous than pure substance, Aluminum alloys are much harder and stronger than pure aluminum. Besides, pure aluminum is rather difficult to cast while many of its alloys are extremely easily cast. Pure aluminum is easily alloyed with other metals. And these combinations possess a great variety of usage. For example, when alloyed with copper, aluminum possesses additional strength. Unfortunately, it is much less corrosion resistive than alloys with manganese, chromium, or magnesium and silicon.



One more advantage of aluminum is that it can be easily remelted over and over again.

Aluminum combined with oxygen forms a new oxide. Its name is alumina. Alumina is a colourless crystallic substance. It is glass hard, solid and extremely durable.

It should be also noted that being an excellent conductor aluminum is widely used in power engineering. It serves for long-distance transfer of electric power.

 

1. Why was aluminum unpopular for a long period?

2. What good qualities does aluminum possess?

3. Where is aluminum in the form of bright foil used?

4. What are the advantages of aluminum alloys?

5. Can aluminum be remelted?

6. In what way is alumina produced?

7. What are its properties?

8. What does aluminum serve in power engineering for?

 

2. Какие качества из перечисленных ниже могу классифицироваться как преимущества и недостатки материалов используемых для строительных целей?

 

ductability, poor conductance, low durability, high corrosion resistance, high purity, low strength, high cost, low cost, excellent conductance, hardness, workability, poor purity, high strength

 

TEXT 7.





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