G azərbaycan respublikasi təHSİl naziRLİYİ azərbaycan texniKİ universiteti M. M. QƏNDİLova e. Q. İsmayilova

JOKES, LAUGHS, SMILES
Voice on phone: “John Smith is ill and can’t attend classes today. He requested me to notify you. ”

Prof: ”All right. Who is speaking? ”

Voice: “This is my roommate”
UNIT XVII
Learn to write well,

not to write at all

Dryden John
SOME WORDS ABOUT METALLURGY

Metallurgy is one of the oldest arts but one of the youngest of sciences. The science which treats of the methods used to obtain the metals in free condition from compounds that occur in nature is called metallurgy Many of our metals were known in ancient times, but it is only within the last century or two that the knowledge of the properties of metals has made it possible to apply them in any extended way for industrial purposes. Iron was used in the earliest times of which we have any historical records. The art of making weapons from iron was known to Egyptians and Hindoos. Iron is obtained by reducing its ores with carbon.

With the development of physics of metals, metallography, theory of heat treatment, and other phases of the science of metals, the field of metallurgy has broadened.

Metallurgy in this broader sense falls into three divisions: chemical or extractive, physical and mechanical. Chemical metallurgy includes the metallurgical processes involving chemical change and the methods of production and refining.

Physical metallurgy deals with the nature, structure and physical properties of metals and alloys.

Mechanical metallurgy includes the processes of working and shaping metals, i.e. the processes which do not involve chemical changes.

Some metals are mined in the native state. Among these are gold, silver, platinum, mercury, tin and copper. Even in the native metals ,however, there is considerable foreign material, such as rock, gravel, sand and the other impurities, which require removal.

Most of the metals, however, are found in the earth in oxide form. This oxide which may be mined with commercial profit is called ore. Ores of different metals are put through various refining processes to obtain the pure metal.

The more common impurities in iron ore silica, titanium, and phosphorus. The ores which contain the smallest amounts of these impurities are the most valuable. Much silica and titanium are undesirable. Phosphorus and sulphur are undesirable too because of their adverse effect on iron and steel.