- •Англійська мова
- •Contents
- •Improvement of materials properties
- •Carbon steels
- •Methods of steel treatment
- •Unit 13 non-ferrous metals. Magnesium
- •Task 1. Give Ukrainian equivalents to the following words and word combinations.
- •Task 1. Give Ukrainian equivalents to the following words and word combinations.
- •Unit 16 non-ferrous metals. Palladium
- •Task 1. Give Ukrainian equivalents to the following words and word combinations.
- •Task 1. Give Ukrainian equivalents to the following words and word combinations.
- •Task 1. Give Ukrainian equivalents to the following words and word combinations.
- •Task 1. Give Ukrainian equivalents to the following words and word combinations.
Task 1. Give Ukrainian equivalents to the following words and word combinations.
come into use, to exceed, demand, to supply, the rapid growth, abundant, magnesium, lightweight, to rank ahead, corrosion resistant, lead, ore deposits, to possess, to contain, application.
Task 2. Fill in the correct words and word combinations from the list below. Use each word only once.
Engineering, large quantities, supplies, abundant, increasing, technological, valuable, beginning, to stimulate, development.
the ... of titanium 6. … development
… in nature 7. great … of titanium
… the demand 8. … metal
practical … material 9. … application
from the very … 10. to contain …
Task 3. Fill in the gaps with the verbs from the list below used in the proper tense form.
to demonstrate, to possess, to realise, to find, to exceed, to discover, to come.
1. Other modern industrial metals, such as aluminium and magnesium, … into use relatively slowly.
2. Titanium … in 1790, but it was not until 1943 that its potentialities …
3. The demand … the supply from the time that it … to be a practical engineering material.
4. Russia … great supplies of titanium.
5.It … increasing application in many different fields.
Task 4. Make up sentences with the following words and word combination.
industrial metals, new uses, different fields, to stimulate, throughout the world, large deposits, to exceed, to supply, to discover, in the case of.
Unit 16 non-ferrous metals. Palladium
Palladium - (named after the asteroid Pallas), Pd; at. wt. 106.42(1), at. no. 46, m.p. 1554.9˚ C; b.p. 2963˚ C, valence 2, 3, or 4. It was discovered in 1803 by Wollaston. Palladium is found along with platinum and other metals of the platinum group in placer deposits of Russia, South and North America, Ethiopia, and Australia. Natural palladium contains six stable isotopes. Twenty five other isotopes are recognized, all of which are radioactive. It is also found associated with the nickel-copper deposits of South Africa and Ontario. Its separation from the platinum metals depends upon the type of ore in which it is found.
Palladium is the lightest of the platinum group and very malleable and ductile when pure. It is a steel-white metal, which does not tarnish in the air, and is the least dense and lowest melting of the platinum group of metals. When annealed, it is soft and ductile, cold working greatly increases its strength and hardness. It resists oxidation at ordinary temperatures and is appreciably volatile at high temperatures. At red heat it is converted into oxide.
It absorbs a considerable amount of hydrogen gas - a unique property of palladium. It absorbs and retains over 800 times its volume of hydrogen at room temperatures, possibly forming Pd2H. It is not yet clear if this is a true compound. Palladium is attacked by nitric and sulfuric acid. It dissolves in warm acidic chloride solutions.
Finely divided palladium is a good catalyst and is used for hydrogenation and dehydrogenation reactions, and as a catalyst in the manufacture of sulfuric acid. Palladium dispersed on carbon or alumina has outstanding catalytic properties. The automotive industry has used palladium in catalytic converters since 1974. Platinum-palladium catalysts are used to control emissions from automobile exhausts. Hydrogen readily diffuses through heated palladium and this provides a means of purifying the gas. The sponge form is used for separation of hydrogen from a mixture of gases. Palladium-silver diffusion membranes are used in the purification of hydrogen.
Like gold, palladium can be rolled into sheet as thin as 1/250,000 in. The metal is used in dentistry, watch-making, in making surgical instruments and electrical contacts, for mirrors in astronomical instruments. When palladium is alloyed with 40% silver it becomes much tougher and wear-resistant and is used in electrical contact materials. Palladium-bearing thick-film pastes are used in miniature solid-state devices and integrated circuits.
In alloyed state it is used in jewelry trades, where palladium hardened with 4-5% ruthenium provides a light, white, strong, tarnish-free alloy for watch cases, brooches, and settings for gems. “White gold” is an alloy of gold decolorized by the addition of palladium. Palladium is also alloyed with platinum for various applications in jewelry.
Alloys are also used for bearings, strings, and balance wheels in watches, for aircraft spark plugs, for protective coatings. Silver alloys are used for electrical contacts, for electrical relays and switching systems in telecommunication equipment, catalyst for reforming cracked petroleum fractions and hydrogenation, metallic ceramics, etc.
Palladium is used extensively in medicine, e.g., it is widely used in dentistry, often alloyed with platinum and gold in dental inlays. A colloidal form of palladium has been used therapeutically for tuberculosis, gout, and obesity.