M. Ibbotson - Professional english in use engineering (794233), страница 9
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This causes a chemical reaction, which deposits zincon the cathode, plating the component.A related process, called anodizing, is used to protect aluminium. The component to beanodized is connected to the positive terminal (to become the anode) and placed in anelectrolyte, with a cathode. As electricity flows, aluminium oxide is deposited on the anode.As this is harder than aluminium metal, it provides protection.32Professional English in Use Engineering13.1Make correct sentences using one part from each co lumn.
Look at A opposite to help you.The first one has been done for you.1 Duralumin \can be mixed with copper to makesilver.2 Titaniumresists corrosion better than the other precious metal,brass.has a high strength-to-weight ratio and is often alloyed withaluminium.4 Copperis an aluminium alloy that also contains copper and............___bronze.5 Goldcan be mixed with tin and lead to produce3Zinc~ magnesmm.13.2Complete the word groups below using the names of the metals in 13.1 above. You will needto write some names more than once. Look at A opposite to help you.13.3Complete the checklist for electroplating using the words in the box.
Look at B opposite tohelp you .anodecathodeelectrolyteelectroplatinggalvanizingnegativeplatedpositive.I Check that there is sufficient (1) ................................ in the bath to completely cover thecomponent, in order to ensure that the component will subsequently be (2) ............................... .over its entire surface area ..I Ensure that the component is connected to the (3) ................................ terminal of the electricalsupply. During the (4) ................................
process, the component should function as the(5) ................................ ..I Ensure that the metal being used for plating- e.g. zinc for (6) ................................ -isconnected to the (7) ................................ terminal of the electrical supply. During the process,it should function as the (8) ................................ ..-----.---electrical supply(direct current)bath containing electro lyte....----~-- e l ectricalsupply(direct current)bath containing electrolytesteel component beingplated= cathode(-)L _ - - - -Electroplati ngmetal being used for plating(e.g.
zi nc) =anode (+)aluminium component being' - -- - - - anod ized =anode (+)AnodizingOv~r .f-o 1:fou ~How are non-ferrous metals used in your industry, or an industry you're familiar with? Iselectroplating common? If so, what kinds of metals are used for plating, and why are thesespecific metals chosen?Professional English in Use Engineering33PolymersNatural and synthetic polymersThe web page below, from a website for engineering students, provides an introduction topolymers .r :_ 1r~1~1With names such as polytetrafluoroethyline and polyethyleneteraphthalate, it's notsurprising that polymers are usually called by their more common name, plastic.But what, exactly, is a polymer or a plastic?Polymers are compounds made up of severalelements that are chemically bound.
Mostcompounds consist of large numbers of tinymolecules, which each contain just a fewatoms . For example, a water molecule- H2 0contains two hydrogen atoms and one oxygenatom. But the molecules of polymers containhuge numbers of atoms, joined together inlong chains.Rubber, thanks to its many uses from rubberA polymer chainbands to car tyres , is one of the best-knownpolymers. It comes from latex, a natural liquid which comes from rubber trees .
Rubberis therefore a natural polymer. However, most of the polymers used in industry arenot natural, but synthetic. The term 'plastic' is generally used to refer to syntheticpolymers- in other words, those that are manmade.Note: Rubber can be natural (natural rubber) or synthetic (synthetic rubber).Thermoplastics and thermosetting plasticsThe page goes on to look at types of polymer.Synthetic polymers can be divided into two main categories:Thermoplastics can be melted by heat, and formed in shaped containers called moulds .After the liquid plastic has cooled, it sets to form a solid material. A thermoplasticis a type of plast ic that can be heated and moulded numerous times.
Examples ofthermoplastics that are common in engineering include:• ABS (acrylonitrile butadiene styrene)- stiff and light, used in vehicle bodywork• polycarbonate - used to make strong, transparent panels and vehicle lights• PVC (polyvinylchloride) -a cheaper plastic used for window frames and pipes.Thermosetting plastics, also called thermosets, can be heated and moulded likethermoplastics. They may also be mixed from cold ingredients . However, during coolingor mixing, a chemical reaction occurs, causing thermosets to cure.
This means they setpermanently, and cannot be moulded again. If a thermoset is heated after curing, it willburn . Examples of thermosets used in engineering are:• epoxy resins- used in very strong adhesives• polyimides- strong and flexible, used as insulators in some electric cables.Two more categories of polymer are engineering plastics and elastomers. Engineeringplastics are mostly thermoplastics that are especially strong, such as ABS and polycarbonate .Elastomers are very elastic polymers which can be stretched by force to at least twice theiroriginal length, and can then return to their original length when the force is removed.34Professional English in Use Engineering14.1Circle the correct words to complete the text.
Look at A opposite to help you.A lot of rubber is made from latex, a (1) natural/synthetic polymer which comes from rubbertrees. However, not all rubber comes from trees. Synthetic rubber is a (2) manmade/naturalpolymer with similar properties to latex. Plastics are also polymers. Like rubber, they consistof long chains of (3) atoms/molecules which form extremely large (4) atoms/molecules.14.2Read the extract describing a plastic panel manufacturing process. Then decide whether thesentences below are true or false, and correct the false sentences.
Look at B opposite to help you.By this stage of the process, the plastic is solid, and has fully cooled. Selected panels can now undergoquality-control testing, to check they are strong enough to cope with the tough conditions they willbe exposed to in use. Tests include tensile testing, where narrow lengths of panel are subjected to hightension loads to check they do not stretch or fracture. More tests are carried out to check the panels'resistance to impacts and scratching.
Any products that fail the tests are returned to the beginning ofthe production process, melted down, and their material is reused.1 The plastic was heated earlier in the process.2 The plastic has now set.3 The plastic is now liquid.4 To pass one of the tests, the plastic must be an elastomer.5 T he description suggests the plastic is a type of engineering plastic.6 The material is a thermosetting plastic.7 The material is a thermoplastic.14.3Complete the word puzzle and find the word going across the page. Look at A and Bopposite to help you.1 a shorter name for polyvinylchloride2345678910111213used for forming melted plastica group of atomsa long chain of atomsto set permanentlya very elastic polymera plastic that sets permanentlya natural polymera very strong thermoset resinnot naturalparticles that form moleculesanother word for 'not natural'material used to make rubber4321-1-1-17-12 13869-1-1 -1-1 -110511-1-11--L--L___L___Ove,r ..f-o /10tc~Talk about specific types of polymer that are used in your industry, or an industry you'refamiliar with .
How are they used? Which of the categories mentioned in A and B opposite dothe polymers belong to?Professional English in Use Engineering35Minerals and ceramics-Mineral and ceramic engineering materialsA mineral is a natural, inorganic material (one that is not living) which is found in theground, often within rocks. Minerals are quite pure. Rocks, on the other hand, can bemixtures of several minerals, and may also contain previously organic material. Examples ofminerals include different types of ore- from which metal can be extracted- such as ironore. Non-metallic minerals include:•diamond, an extremely hard form of carbon (C), which is used as an abrasive (very hardand rough) material in cutting tools- frequently referred to as industrial diamond whenused in engineering•silicon (Si), found in sand as silica (silicon dioxide- Si02), which can be heated to hightemperatures to make glass.Generally, inorganic, non-metallic materialsthat have been formed by heating are calledceramics.
Glass is therefore a ceramic. Whenmaterials are heated to extremely hightemperatures to form ceramics that are glasslike - that is, with a structure like that of glass- we say that they are vitrified.Ceramic materials are used to makeconstruction materials such as bricks. Theseare made from clay, and are then fired in akiln- that is, heated to a high temperature inan industrial oven.
Clay can also be vitrified for example, to make waterproof pipes.IIIIIIIICilClay bricksGlassA technical adviser for a glass manufacturer is giving a briefing to a group of engineers at atrade fair.'Sheets of glass, which are obviously flat and thin, are called float glass. This refers to themanufacturing technique where molten glass is floated on molten tin, to produce flat sheets.Usually, after float glass has been formed, it's annealed - it's left to cool slowly. But if it's leftin this state, and the glass later gets broken, it breaks into dangerous, sharp pieces. So formost engineering and architectural uses, annealed glass is unsuitable. We need to use what wecall safety glass.''One type of safety glass is toughened glass, also called tempered glass.
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