Read and memorize the following words.
lustrous ['Lvstras] блестящий
value ['vaelju:] ценить, величина
precious I 'prejas] драгоценный
plating ['pleitiq] покрытие
vary f'vesri] менять, изменять, изменяться
throughout [8ru(:)'aut] повсюду, везде, все время
coating ['koutiij] покрытие
palladium [pa'leidiam] палладий
malleable ['mzeliabl] ковкий
incident ['msid(s)nt] (физ.) падающий (луч)
infrared ['infra'red] инфракрасный
visor ['vaizs] противосолнечное отверстие, солнцезащитный козырек
chromium ['kroumjsm] хром
disperse [dis'pa:s] рассеивать, распространять
nickel fnikl] никель
total ['toutl] общий, полный, абсолютный
harden f'ha:dn] делать твердым, придавать твердость
powder ['paudaj порошок
occur [э'кэ:] происходить, встречаться
Read and memorize the following word combinations.
printed circuit - печатная схема platinum-group metals - платиновые металлы air-conditioning requirement - требования к кондиционированию воздуха
steel-grey metal - металл серого цвета с голубоватым отливом
natural deposit - природное месторождение
3. Read the international words. Guess and memorize their meanings.
decorative, fabrication, total, history, attraction, comparator, million, inert, to reflect, radiation, protection, to disperse, to combine, special, character, oxide, variant, machine, instrument, extensive, pigment
Text 4. Metals: Silver, Gold, Chromium
Silver. Silver is a white, lustrous metal valued for its decorative beauty and electrical conductivity. Its specific gravity is 10.5, melting point 1,861.4 °F (960.8 °C). Together with gold, and the platinum-group metals, silver is one of the so-called precious metals. Silver has the highest known electrical and thermal conductivity of all metals and is used in fabricating printed circuits and as a coating for electronic conductors; it is also alloyed with such elements as nickel or palladium for use in electrical contacts. Silver is widely distributed in nature, but the total amount is quite small when compared with other metals; the metal constitutes 0.05 parts per million of the Earth's crust.
Gold. Gold is a dense, lustrous, yellow precious metal. Its specific gravity is 19.3 (at 20°C), melting point 1,945 °F (1,063 °C). Gold has several qualities that have made it exceptionally valuable throughout history. It is attractive in colour and brightness, highly malleable, and usually found in nature in a comparatively pure form. Gold is one of the heaviest of all metals. It is a good conductor of heat and electricity. Its abundance in the Earth's crust is estimated at about 0.005 parts per million. Because of its high electrical conductivity (71 percent that of copper) and inertness, the largest industrial use of gold is in the electric and electronics industry for plating contacts, printed circuits, and semiconductor systems. Thin films of gold that reflect up to 98 percent of incident infrared radiation have been employed on satellites to control temperature and on space- suit visors to afford protection. Used in a similar way on the windows of large office buildings, gold reduces the air-conditioning requirement and adds to the beauty.
Chromium. Chromium is a hard, steel-grey metal that takes a high polish and is used in alloys to increase strength and corrosion resistance. Its specific gravity is 7.20 (at 20°C), melting point 3,434°F (1,890°C). Chromium is a relatively abundant element in the Earth's crust. It is widely dispersed in natural deposits, where it is always combined with other elements, especially oxygen. Chromium is added to iron and nickel to produce alloys specially characterized by their high resistance to corrosion and oxidation. Used in small amounts, chromium hardens steel.
Stainless steels are alloys of chromium and iron in which the chromium content varies from 10 to 26 percent. Chromium alloys are used to fabricate machine and instrument parts when chemical and heat resistance are required. Chromium oxide is a green powder and is employed extensively as a pigment for paints.