6.5. Form the nouns denoting properties.
Model: weak – weakness, durable – durability [‚dj|әrә´bılәti], plastic – placticity [plæ´stısәti], long – length
brittle
elastic
flexible
hard
light
|
opaque
rigid
soft
strong
tough
|
6.6. Read the text and complete the diagram describing the classification of engineering materials.
Engineering Materials
Engineers have to know the best and most economical materials to use. Engineers must also understand the properties of these materials and how they can be worked. There are two kinds of materials used in engineering – metals and non-metals. We can divide metals into ferrous and non-ferrous. The former contain iron and the latter do not contain iron. Cast iron and steel, which are both alloys, or mixtures of iron and carbon, are the two most important ferrous metals. Steel contains a smaller proportion of carbon than cast iron. Certain elements can improve the properties of steel and are therefore added to it. For example, chromium may be included to resist corrosion and tungsten to increase hardness. Aluminium, copper, and the alloys (bronze and brass) are common non-ferrous metals.
Plastics and ceramics are non-metals; however, plastics may be machined like metals. Plastics are classified into two types – thermoplastics and thermosets. Thermoplastics can be shaped and reshaped by heat and pressure but thermosets cannot be reshaped because they undergo chemical changes as they harden. Ceramics are often employed by engineers when materials which can withstand high temperatures are needed.
6.7. Draw similar diagrams displaying the connection between the following:
alloys, copper, brass, pure metals, aluminium, metals;
computer system, CPU, hardware, main memory, peripherals, software;
aeronautical engineering, civil engineering, electrical engineering, engineering, heating and ventilating, marine engineering, mechanical engineering.
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