Урок 4 Тема. Чёрные и цветные сплавы
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Задание 1. Составьте аннотацию текста. Задание 2. Прокомментируйте следующие тезисы, используя выражения из задания 2 стр. 22 (урок 2).
TEXT 7. TITANIUM AND ITS ALLOYS prompt v – побуждать, толкать; подсказывать reduction process n – процесс отделения металла от руды Titanium was first identified as a metallic element by Gregor in England in 1791. Several years later, Klaproth in Germany named the metal after the Titans of Greek mythology. Production of high-purity titanium, because of its having a strong tendency to react with oxygen and nitrogen, proved difficult, and it was not until the middle of the 20-th century (1938 – 1940) that a commercial process was developed. Titanium industry began to take form shortly after the end of World War II. Commercial interest was prompted by the relatively 1оw density of titanium (between those of aluminium and iron), its excellent corrosion resistance and its wide occurrence in mineral deposits. Titanium ore deposits are of two types – one based on rutile and the other on ilmenite. Ilmenite is the chief titanium ore used in Russia. The estimated titanium content in the earth's minerals indicates that it is the fourth most abundant metal of commercial significance. Only aluminium, iron and magnesium are more abundant. However, despite the abundance of the metal, production of titanium is comparatively expensive because of the complexity of the reduction process. Titanium and its alloys are used primarily because of their unique corrosion resistance and strength. The combination of high strength, stiffness, good toughness and low density at very low to moderately elevated temperatures allows weight savings in aerospace structures and other high-performance applications. The first actual production application of titanium was in the aircraft industry. Now it is used in both commercial and military aircraft building – for airframes of jets, for compressor disks and blades of jet engines. It is also used in the space industry. Titanium alloys are used in the chemical industry – for manufacturing heat exchangers, process tubing, reaction vessels, fittings, pump and valve components, and gas compressors. Задание 1. Составьте аннотацию текста. Задание 2. Прокомментируйте следующие тезисы, используя выражения из задания 2 стр. 22 (урок 2).
TEXT 8. Materials for pipelines sacrifice ['sxkrIfaIs] n – жертва, ущерб lb/in2 (psi – pound per square inch) – фунт/кв.дюйм spiral ['spaIql] n – спираль wind [waInd] (wound [waund], wound) v – наматывать friction n – трение ease [Jz] n (of handling) – лёгкость (обращения, транспортировки) yield [jJld] strength n – предел текучести inferior [In'fIqrIq] a – худший Pipe steel is by far the most costly item of pipelines; it may constitute some 35-45% of the total cost. Bending apparatus and welding skills have improved greatly in recent years and tensile strength has been greatly increased without sacrifice of bending and welding qualities. Today, steel with a tensile strength of up to 60 000 lb/in2 can be used economically, allowing thinner wall pipes to be employed so that total weight, and therefore costs, can be reduced. The improvement is partly due to the addition of small quantities of such metals as columbium, titanium and vanadium, and partly due to better manufacturing techniques. Steel pipes for trunk lines may be seamless or welded, welding being particularly applicable for large diameter pipes. During the last few years advances have been made in the employment of spiral weld pipes formed from a steel strip spirally wound, with the edges joined by submerged arc welding. Aluminium has some technical advantages over steel, such as lower friction factors, resistance to certain types of corrosion and lighter weight (30-35% less than steel). However, since the joint factor for welding is lower than that of steel, and the limited yield strength makes it essential to have heavier wall pipe than for high yield strength steels, aluminium has not so far been able to compete economically with steel under normal pipeline conditions. Plastic pipes also have advantages, such as low density, resistance to corrosion and chemicals, and ease of handling, but they are still inferior to metal pipes in their ability to withstand extremes of temperature and pressure. Задание 1. Составьте аннотацию текста. Задание 2. Прокомментируйте следующие тезисы, используя выражения из задания 2 стр. 22 (урок 2).
TEXT 9. History notes The capability of one metal to protect another was recognized as early as the fifth century BC when the use of a metallurgically applied coating of tin on iron was described. Nonetheless in 1975 the National Bureau of Standard estimated that the annual cost of corrosion in the U.S. was about 70 billion dollars, of which about 10 billion could have been avoided using known prevention techniques. A 1996 report claims the yearly cost of corrosion has skyrocketed to 160 billion dollars. Generally only the more noble metals like copper, gold, silver and the platinum-group metals exist in the earth’s crust in their uncorroded state. Metallic corrosion can be defined as the destructive interaction of a metal with the environment surrounding it. This interaction can occur by immersion in acids or, depending on the type of the environment, exposure to atmospheric moisture or contaminants. For instance, the pleasing green patina found on many copper monuments is essentially basic sulfate of copper. Normally, the atmosphere in most industrialized urban areas contains various combustion products (e.g., sulfur dioxide), which substantially increase the rate of patina formation. Perhaps the most clear example of this is the patina that has formed on the Statue of Liberty during its more than 100 majestic years in New York Harbor. (“Plating and Surface Finishing”). Задание 1. Составьте аннотацию текста. Задание 2. Прокомментируйте следующие тезисы, используя выражения из задания 2 стр. 22 (урок 2).
TEXT 10. a new method of Hot water pipes protection Researchers in Russia have developed a method for ensuring the longer life for hot water pipes by addition of liquid silicate to the water. The test during which micro-additives are added to the water at regulated intervals have proved remarkably successful. The liquid silicate does not affect the quality of the water itself, but forms a hard internal coating in the pipes (usually made of cast iron), in this way reducing the problems of cavitation and corrosion, and prolonging the pipe life. At present, further research is being carried out into this technique, and details are awaited on its suitability for other similar applications. Задание 1. Составьте аннотацию текста. Задание 2. Прокомментируйте следующие тезисы, используя выражения из задания 2 стр. 22 (урок 2).
TEXT 11. Pipelines Protection wrap [rxp] v – заворачивать, обёртывать tape n – лента butyl rubber ['rAbq] n – бутилкаучук brush type scraper [sk'reIpq] n – скребок Without special protection buried pipelines would be subjected to corrosion, which is essentially electro-chemical in nature. The steel of the pipeline and the chemicals in the soil may cause electric currents to flow from the soil at certain points (anodes) and from the soil to the pipe at others (cathodes). Corrosion takes place where the currents leave the pipe. Buried lines are therefore coated with layers of bitumen or coal tar, asbestos felt and/or glass fibre, the exact type of wrapping depending on local conditions. Synthetic plastic coatings are relatively new, but tapes made from polyethylene or butyl rubber appear promising. In recent years the increased use of cathodic protection has reduced external corrosion to negligible proportions. In this method an electric current is made to flow towards the surface to be protected; that is to say, the whole pipeline is rendered cathodic. Corrosion may also occur internally, though crude oil lines are generally immune. Rust and scale, which build up inside refined products lines, reduce their capacity and are dealt with by chemical inhibitors and by cleaning the line with brush type scrapers. Задание 1. Составьте аннотацию текста. Задание 2. Прокомментируйте следующие тезисы, используя выражения из задания 2 стр. 22 (урок 2).
TEXT 12. HARD Material coating process IN VACUUM A German firm has developed a process for improving the wear and corrosion resistance of tool and machine elements subjected to high level of wear. In vacuum at a temperature of approximately 1,000°C, the parts are coated with a thin layer of hard materials such as titanium carbide, titanium nitride or aluminium oxide. Each layer is only a few thousands of a millimetre thick. Carbide metals, stainless steels, ceramic nitrides and other materials which can be subjected to high thermal loads are all suitable for treatment by this process. (“Anti-Corrosion”). Задание 1. Составьте аннотацию текста. Задание 2. Прокомментируйте следующие тезисы, используя выражения из задания 2 стр. 22 (урок 2).
TEXT 13. Gas welding bring (about) v – осуществлять handle n – рукоятка needle valves n – игольчатые клапаны tip n – наконечник storage ['stOrIG] tank n – зд. баллон In gas or oxy-acetylene welding a high temperature flame is produced by igniting a mixture of two gases, usually oxygen and acetylene, in correct proportion and at proper pressure. Besides acetylene natural gas, producer gas or liquid gas may also be used for the process in question. The welding is brought about by first preheating the metal pieces to be welded with the gas flame, after this, when the base metal is at its melting temperature the weld metal is added by melting a filler rod of suitable composition with the gas flame. The gas welding process requires a supply of both oxygen and acetylene devices for mixing and regulating the flow of the mixtures. The device for the process under consideration is a torch consisting of a handle, two needle valves, tubes for oxygen and for acetylene, a head and a tip. The regulators on the storage tanks serve to control the working pressure of both gases. The mixing of acetylene and oxygen takes place in the head of the torch, where oxygen meets cross current of acetylene. Acetylene and oxygen are delivered at a certain pressure – from 1 to 10 psi depending upon the size of the tip available and upon the thickness of the metal to be welded. The method is cheap and finds a wide application in industry. Задание 1. Составьте аннотацию текста. Задание 2. Прокомментируйте следующие тезисы, используя выражения из задания 2 стр. 22 (урок 2).
TEXT 14. Electric ARC welding Electric arc welding is a fusion welding process in which the surfaces to be joined are fused by the heat of an electric arc. By bringing the work and the electrode together as conductors, an electric circuit is established, then by separating the conductors an electric arc is created in which the electrical energy is converted into heat reaching the temperature of approximately 7,000°F. Fused metal is obtained by deposit from an external source, the metal being supplied by melting the welding electrode in the arc, then fusing it with the locally molten base metals. Arc welding depends upon the presence of a continuous current across the arc, voltage varying from 15 volts to 60 volts. The size of the work to be welded and that of the welding rod determine the current demand. Either direct or alternating current may be employed by this process, although direct current has a wider application. Задание 1. Составьте аннотацию текста. Задание 2. Прокомментируйте следующие тезисы, используя выражения из задания 2 стр. 22 (урок 2).
TEXT 15. Electric Resistance Welding flash welding n – сварка оплавлением percussion [pW'kASqn] welding n – ударная сварка projection welding n – рельефная сварка This type of welding is a pressure process. It consists of heating metals to their plastic temperature, then applying pressure mechanically to achieve a complete union of the parts. Resistance welding processes form a group embracing many types of welding, their selection depending upon the equipment to be used. Essential equipment consists of a machine designed with a transformer for altering the available current (increasing the amperage and reducing the voltage), electrodes for clamping the work and transmitting the current, a suitable mechanism for applying pressure to the parts to be joined and another one for controlling, regulating and timing the flow of the welding current. The types of resistance welding are: spot welding, butt welding, flash welding, percussion welding, seam welding and projection welding. Задание 1. Составьте аннотацию текста. Задание 2. Прокомментируйте следующие тезисы, используя выражения из задания 2 стр. 22 (урок 2).
TEXT 16. Every echo TelLs a story flaw [flL] n – трещина, разрыв, дефект It usually takes several hours to make a detailed inspection of the welded joints on pipelines, ships, refineries and nuclear power plants. A new method devised at the Denish Welding Institute in Glostrip, Denmark, can reduce this time to a few minutes, and still provide more information about the flaws or weaknesses in the joints. The P-scan system uses computer-controlled ultrasonic equipment that records echo signals from the interior of the welded joint on a magnetic tape. These signals can be viewed immediately on television monitors and can also be stored on the cassette tapes for future analysis. For written reports, the signal pattern can be printed on paper. The P-scan method is more precise than X-ray radiograph of current ultrasonic inspection systems, its developers say. It shows the exact location of any flaw, and provides three-dimensional views of its size and shape from two perspectives, a top view and a side view. According to the Institute, this is the first time it has been possible to obtain such complete documentation of internal cracks and other welding defects. “Newsweek” (New York, N.Y.) Задание 1. Составьте аннотацию текста. Задание 2. Прокомментируйте следующие тезисы, используя выражения из задания 2 стр. 22 (урок 2).
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