Bronze and brass

About 6,000 years ago, people discovered that copper could be made harder if mixed with tin. This alloy is called bronze. It was so widely used for many years that this period of tirne became known as the Bronze Age.

If you had been a soldier in Ancient Greece you would have had to stop in battle to straighten your bronze sword. But bronze was a great improvement of copper, which bends even more easily. Most pure metals are weak and soft. But two soft metals mixed together make a harder metal called an alloy. Bronze is an alloy of copper and tin. It was the first alloy.

Tin was the fifth metal discovered by man. It is a soft whitish substance. Various proportions of the two metals produced different qualities in the bronze. Earlier there were used about eight parts of copper to one of tin. Because weapons made of bronze were harder and stronger than those of copper, tin became very important. However, there was little tin to be found in Western Asia still the centre of the metal-working world. Mostly it was found in Europe, and the mer­chants of Troy, who brought their goods to Europe, began loading their boats with tin on their return journeys. In England, tin was discovered and mined in Cornwall and was a main export for a long time.

When zinc was discovered it was used to produce an important alloy in combination with copper. This alloy was brass, a hard-wearing, yellow metal which was valued more than bronze. The exact date of discovery is uncertain but it was probably about 200 ВС. Brass is often mentioned in the Old Testament, most of which was written before zinc was discovered and therefore when there could not have been any brass. The biblical metal must have been either bronze or

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copper, and the word brass is the result of a translator's error at some time. So, bronze and brass were the first alloys - man-made metals.

Vocabulary notes

If mixed with tin if you had been a soldier to straighten sword

Improvement to bend

there were used about eight parts of copper to one of tin because weapons made of bronze were harder and stronger than those of copper

there was little tin to be found in Western Asia - still the cen­tre of the metal working world to load

hard-wearing

the exact date of discovery is uncertain to mention the Old Testament when there could not have been any brass

the biblical metal must have been either bronsze ov copper

если смешать с оловом если бы вы были солдатом выпрямлять шпага, меч зд. достижение сгибать(ся), гнуть(ся) использовали около восьми час­тей меди на одну часть олова поскольку оружие, сделанное из бронзы, было тверже и прочнее того, что изготавливали из меди в Западной Азии было мало оло­ва, несмотря на то, что она была центром металлообработки в мире загружать износостойкий

точная дата открытия не из­вестна упоминать Ветхий Завет когда ещё не могло быть латуни

библейским металлом, должно быть была либо бронза, либо медь

Exercises

1. Find international words in the text.

2. Find English equivalents for the following

большинство чистых металлов сплав

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мягкий металл беловатого цвета

оружие, сделанное из бронзы

Бронзовый век

износостойкость

упоминать

ошибка

добывать олово

3. Match the English words and word combinations given below with the Russian equivalents

1. mixed with tin а) либо бронза, либо медь

2. a main export b) до нашей эры

3. return journey с) в сочетании с

4. ВС (Before Christ) d) в сочетании с оловом

5. the Old Testament e) обратное путешествие

6. in combination with 0 Ветхий Завет

7. either bronze or copper g) основной предмет экспорта

4, Answer the following questions

1. Why was bronze a great improvement of copper?

2. What does bronze consist of?

3. Where were the major tin deposits located?

4. What alloy was produced of zinc in combinations with copper?

5. Why was brass valued more than bronze?

5. Translate at sight and compare the components of brasses and bronzes. Define these alloys

The most widely used alloys are brasses, bronzes and aluminium alloys.

Brasses are the alloys of copper and zinc mixed in different pro­portions. An addition tin makes brasses stronger. Brasses are very duc­tile, corrosion resistant and may be treated without heating. They are used for making musical instruments, bearing, etc.

Bronze is usually an alloy of copper and tin. It has such proper­ties, as hardness, resistance to wear, corrosion resistance and relatively high strength. The most common and commercially important bronzes are known as strength bronze, phosphor bronze and manganese bronze. They may be cost and machined with ease.

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CHAPTER

2

MANUFACTURING PROCESSES

Sect/ on 1 FOUNDRY

Unit 1

METALS AND THEIR PROPERTIES

Elements are simple substances the matter is composed of. Each chemical element has a definite atomic number and definite properties. All elements are arranged into one orderly table elaborated by D.I. Mendeleyev, a great Russian scientist. Most of the elements known are solids at room temperature although some are gases or liquids.

Over two-thirds of the elements are characterized by metallic luster, high electrical and thermal conductivity and, in most cases, a capacity for being shaped or deformed plastically without rupture. But metals in their pure form are seldom used in engineering practice. Most of the metallic materials used in engineering are combinations of met­als known as alloys. An alloy is a metallic substance containing more than one element. Metals and alloys are the most useful engineering materials. They have their own properties which may be divided into three classes: physical, mechanical and chemical properties.

The characteristics employed to destribe a material under cer­tain conditions in which external forces are not concerned are called physical properties. The description of the physical behaviour of a ma­terial will include such characteristics as specific heat, thermal conduc-^tlvity, coefficient of expansion, colour, strength, and hardness.

The mechanical properties are those describing the material be­haviour under the action of external forces. These properties relate primarily to the elastic and plastic behaviour, as well as, to the overall

strength and fracture characteristics of the materials.

The chemical properties describe the combining tendencies, cor­rosion reactivity, and solubility of a substance, etc.

Exercises