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An alloy that does not sink




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SMELTING IN LIQUID BATH

Smelting in a liquid bath, a new process for the recovery of heavy non-ferrous metals, features high efficiency and meets ecological requirements. It was developed by scientists at the oscow Institute of Steel and Alloys in conjunction with experts from Kazakhstan.

The innovation is as follows: oxygen is pumped into the furnace, which accelerates the ■ ^ very process dozens of times, increases the output of copper, nickel and other valuable.:mponents from their ores. In addition, it considerably reduces air pollution.

The high technical and economic characteristics of this type of smelting have been:-oved at the Norilsk mining combine (northern Russia), which implemented this process for the ~:st time. A new type of furnaces is being developed for mining combines and other projects of::i-lerrous metallurgy.

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2) METALS AND ALLOYS

From the earliest times metals and their alloys were and are referred to as the basic rscoring materials. Lately new branches of industry have been developed, for example, nronic, atomic and space industries. The need for new metallic materials has enormously -eased. Metals which were practically unhearcl of before, such as germanium, plutonium and rium have come to light. Besides, high-temperature alloys for power plants capable bf:standing oxidation and erosion, new ferro-magnetic materials, constructional steels intended operating under severe stresses and at extremely high or low temperatures have been

Each metal or alloy possesses a certain distinct combination of properties which differs it n other metals and alloys and bv which metals and alloys are determined for a given neering application. This combination of properties may be varied by alloying with other nents.

Before starting to study the properties of metals and alloys we should get an idea of what terms "pure metal" and "alloys" mean. The term "alloy" is commonly used to describe a aliic solid Containing two or more metals and metalloids. The properties of an alloy are uenced by the properties of the elements it consists of. As a rule, alloys are defined by their tin ant element which is present in a quantity over 50% (per cent) by weight, the remainder alloying elements and impurities. There are a lot of alloys, for example, copper-base alloys, "inium-base alioys and so on.

The term "pure metal" is used for materials from which almost all chemical elements but are eliminated..

The designation "metal" is sometimes applied in metallurgy to any metallic materials ":ut making any distinction between a pure metal and an alloy. The first definition of the a "metal" was formulated by M.V. Lomonosov in the following way: "A metal is a bright a that can be forged". This definition is still true. The metallic luster and the ability for plastic: rmation are, in fact, looked upon as the characteristic features of metals,. The most important are of metals, however, is their high electrical conductivity which decreases as the:erature is raised.

In conclusion it's necessary to mention that metals and alloys are the most important aeering materials due to their excellent properties.

 

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AN ALLOY THAT DOES NOT SINK

1. A magnesium-lithium alloy has been developed at the A. Baikov Metallurgy Institute. The new alloy has 2 main advantages - it is as light as wood and doesn't sink in water.

2. The first component of the alloy - magnesium - is lighter than aluminium and superior to it in heat capacity and in its ability to act as the main component of various structural materials. It is, in fact, 1.5 times lighter than aluminium and 4.5 times lighter than iron. I: doesn't give off sparks from friction or being struck, and is easy to work with and weld. Magnesium is also one of the most widespread metals. Its resources are dozens of times higher than those of nickel, zink and lead.

3. As for lithium, the third element on the Mendeleyev periodic table, it is the lightest of all metals. Everything new and unusual appearing today in metallurgy, chemistry and power- engineering is to a large extent connected with lithium. Lithium is paid much attention to by scientists. According to experts' opinion, there is much more lithium in the earth's crust, than, say, zink or tin. Another interesting fact: over the past 20 years alone, the production of lithium metal in the West has increased 100-fold.

4. The technology of obtaining magnesium-lithium alloys is very complex. An electrically-heated crucible with magnesium and lithium is hermetically sealed and all air is pumped out of it. Instead, the crucible is filled with argon, an inert gas. Melting, pouring and cooling are all done in an airless medium.

5. The new alloy will be widely used in those branches of engineering where lightweight metals are required to produce machine parts, equipment, instruments and house-hold articles.

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3) BASIC ENGINEERING PROCESSES

 

The processing of metals is considered to be the most important part of fabricating a wide -v:: products, such as the tiniest parts used in electronics, electirtcal and radio engineering,. -making, all kinds of measuring devices, etc., on the one hand, and gigantic parts for turbines, engines, machine-tools and even whole sections of machines to produce machinery, on the other hand.

Metal processing is known to involve the following major techniques: casting, forming, machining, joining and heat treatment.

Casting may be briefly described as shaping by means of transforming the metal from the liquid to solid state in specially designed moulds. Some castings are used as they come from the mould, others require machining and finishing operations.

Forming, contrary to casting, is shaping metals in the solid state, which is possible due to the peculiar property most metals possess, called "ductility". Forming includes roiling, forging, stamping and pressing.,,,

Machining is removing the excess metal from cast, rolled or forged parts in order to obtain a desired shape. To achieve the desired result various kinds of machine-tools are employed. The most important machine-tools include the milling, Coring and grinding machines and the lathe, which is one of the most widely used production machines.

Joining includes welding, soldering, brazing and riverting which are used for attaching one surface to another.

Heat treatment is used to improve the properties of metals by controlled temperature changes. It is possible to impart the metal high mechanical properties required for the operation of modern machinery and tools. There are four major groups of heat treatment, namely: hardening, annealing, tempering and normalizing.

The knowledge of all fabricating processes is believed to be necessary for a processing engineer, in order to choose the most suitable and economical technique.

 





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