Text в Superhard Material from Powder.

The development of the engineering, electronic, radiotechnical and electrotechnical industries is unthinkable without materials with special properties. They include, in particular, composite materials, i. е., materials that combine incompatible properties, plastics, etc.

Powder metallurgy figures prominently in obtaining these and other materials. Composite materials¹ have been produced by the hot compaction methods , which are better in their properties, especially in durability, than similar materials obtained abroad, the antivibration alloys of the "iron-copper" type made it possible to double the durability of drilling tools. This increased labour productivity by 20 percent. Welding electrodes made of powders used for resistance welding are 9-12 times more durable than those made by conventional methods³.

composite materials - композиты ² hot compaction method - метод горячей прессовки conventional method - обычный метод

The operational principle of powder metallurgy is very well known - an item of necessary size is modeled, in a mould, out of very small metal grains. After that the item is put into an electrothermic furnace where the grains get sintered together.

The coefficient of the use of metal grows by five times. True, powders more often than not cost more than metalrolling. But labour input is roach' smaller and labour productivity -higher. As a result of that, an item made of powder is over three times cheaper. This saving is achieved on account of a complete or partial liquidation of machining the item, the reduction of metal consumption by half or more, and automation of pressing and sintering.

The tine of operation of powder articles increases considerably. The sintered articles have already proved their advantages working in outer space, in deep sea conditions and inside various machines.

It has been estimated that the output of 1,000 tons of powder articles saves the labour of 190 workers, frees 80 metal-cutting rolled stock and some 1.5 million roubles.

Russian scientists have attained considerable success in powder metallurgy. They were the first in the world to develop, using liigh-energy molding methods, a new Superhard material out of boron nitride. The priority of Russia in developing the first article out of the so-called viscous ceramics has been recognized in many contries.

Exercise 12. Look through the text and say whether it corresponds to the title.

Exercise 13. Define which of this statements is right or wrong using the phrase: it is right (wrong).

Materials with special properties include composite materials, plastics, etc.

Welding electrodes made of powders are not more durable man those made by conventional methods.

An item made of powders is over 3 times cheaper.

The sintered articles have no advantages.

The priority of Russia in developing powder metallurgy has been recognized in many countries.

Exercise 14. Translate the passages "Powder metallurgy ..." and "The coefficient of the use..." in writing.

Exercise 15. Read the text again and find the main idea in every passage. Write it down.

Exercise 16. Say what information of the text is new to you and what information you are already familiar with.

Exercise 17. Make up a plan of the text.

Exercise 18. Speak on the following:

the advantages of the composite materials;

the coefficient of the use of powders; -b) the usage of the sintered articles;

c) the successes of the Russian scientists in powder metallurgy. Exercise 19, Render the text according to the plan in your own words.