I. Reading Activity and Speech Practice
IV.1 Can you read the names of the given chemical elements? Guess their Russian equivalents.
IV.2 Match the given English words given on he left with their Russian equivalents on the right.
IV.3 Read the text to find the answers to the following questions: 1. Which metals have a wider variety of characteristics: ferrous or non-ferrous? 2. What non-ferrous metal is the lightest (the heaviest)? 3. What non-ferrous metal is the most abundant? 4. What metal has the highest melting point? Text D: Non-Ferrous Metals Although ferrous alloys are specified for more engineering applications than all non-ferrous metals combined, the large family of non-ferrous metals offers a wider variety of characteristics and mechanical properties. For example, the lightest metal is lithium, 0, 53 g/cm³, the heaviest, osmium, weighs 22,5 g/cm³ - nearly twice the weight of lead. Mercury melts at around – 38 ºF, and tungsten, the metal with the highest melting point, liquefies at 6,170 ºF. Availability, abundance, and the cost of converting the metal into useful forms – all play important parts in selecting a non-ferrous metal. One ton of earth contains about 81,000 g of the most abundant metal of land, aluminium. One ton sea water, on the other hand, contains more magnesium than any other metal (about 1,272g). All sources combined, magnesium is the most abundant metal on the Earth. But because magnesium is difficult to convert to a useful metal, it may cost several times that of the least expensive and most easily produced metal, iron billet. Although nearly 80% of all called “metals”, only about two dozen of these are used as structural engineering materials. Of the balance, however, many are used as coatings, in electronic devices, as nuclear materials, and as minor constituents in other systems.
IV.4 Explain how you understand the following statement from the text: “Although ferrous alloys are specified for more engineering applications than all non-ferrous metals combined, the large family of non-ferrous metals offers a wider variety of characteristics and mechanical properties.” ( Use the text if necessary).
Text E: Some more about Non-ferrous Metals Non-ferrous are metals and alloys the main component of which is not iron but some other elements such as aluminium, copper and others. Some of the characteristics of non-ferrous metals are high electric and heat conductivity, high corrosion resistance, light weight and ease in fabrication. We know aluminium to be one of the best known light metals. Aluminium was first produced in the laboratory in 1825 by reducing aluminium chloride. However, wide acceptance of aluminium as an engineering material did not occur until World War II. Since then usage of aluminium has steadily increased each year. Aluminium is said to be a white silvery metal which does not rust in the air. Its good corrosion resistance and law density permit it to be widely used in the field of transportation. It is to be noted that aluminium is highly ductile and can be shaped easily by a wide variety of methods and can be rolled. The tensile strength* of aluminium is low in comparison with that of iron. The good electrical conductivity of the metal makes it suitable for many applications in the electrical industry. Everybody knows aluminium to be used extensively for coatings that must be light in weight, light in colour or that must not rust. To make aluminium harder it is necessary to add some other metals to it. Copper, zinc and iron are the metals that alloy freely with aluminium. Historically, copper became one of the first engineering metals. It is known to have been used in prehistoric times for making weapons and tools. Later it was alloyed with tin to form bronze. Having very high electric conductivity and high corrosion resistant qualities, pure copper is a good conductor. However, copper alloys qualities, are stated to be more widely employed, chief among them are brasses* and bronzes *. Brasses are alloys of copper and iron in different proportions. Bronze is an alloy containing primarily copper and tin *, but other elements can be added to the alloy to improve its properties such as hardness and resistance to wear. Additions of some other elements to copper alloys permit certain properties to be made better. Vocabulary to the text: 1. tensile strength* - прочность на разрыв(на растяжение); 2. brass* - латунь; 3. bronze * - бронза; 4. tin * - олово. IV.5 Answer the questions to the text. 1. What kinds of metals are called non-ferrous? 2. What are the main characteristics of non-ferrous metals? 3. When aluminium was first produced? 4. What colour is aluminium? 5. Is it more widely used in machine-building or in transportation? 6. What are the basic characteristics of aluminium? 7. Are there any metals that alloy freely with it? 8. What was the first engineering metal used by a man? 9. What property of copper is the most attractive for modern engineering technologies? 10. Which alloys with copper are the most widely known and used today?
IV.6 Study the table given below. Compare the properties of various copper alloys. Get ready to speak about the ways these alloys are used. Don’t forget to express your own opinion.
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