Page 51 - Curriculum Visions Dynamic Book

a coating on eir efficiency.
(Below) By the middle of the 20th century both machines and tools were made entirely from metal. As a result, productivity soared.
(Above) Metals have
been developed for many specialized purposes.
This dentist’s needle, for example, is made of titanium. Previously, needles were made of steel, and they had
a tendency to snap inside the patient. The titanium ones do not snap; they just bend.
Pure titanium is easily bent and lies between aluminium and iron in density. However, when added to other metals, it can dramatically improve their corrosion resistance and strength. Titanium as a base metal is also widely used where lightness and corrosion resistance are important. It is used in aircraft, spacecraft, for artificial limb joints, and even for the casing of some portable computers.
(Below) Titanium is used as some drill bits to increase th
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