October 31 - November 3, 2004
Element of the Day
Wednesday, October 27
Archaeological
evidence suggests that people have been using tin for at least 5500 years. Tin
is primarily obtained from the mineral cassiterite (SnO2) and is extracted by
roasting cassiterite in a furnace with carbon.
Discovered by: known since ancient times.
Uses: Tin resists corrosion and is used as a protective coating on other metals. Tin cans are probably the most familiar example of this application. A tin can is actually made from steel. A thin layer of tin is applied to the inside and outside of the can to keep the steel from rusting. Once widely used, tin cans have largely been replaced with plastic and aluminum containers.
Tin is used in the Pilkington process to produce window glass. In the Pilkington process, molten glass is poured onto a pool of molten tin. The glass floats on the surface of the tin and cools, forming solid glass with flat, parallel surfaces. Most of the window glass produced today is made this way.
Tin is used to form many useful alloys. Bronze is an alloy of tin and copper. Tin and lead are alloyed to make pewter and solder. An alloy of tin and niobium is used to make superconductive wire. Type metal, fusible metal, bell metal and Babbitt metal are other examples of tin alloys. Tin salts can be sprayed onto glass to make electrically conductive coatings. These can then be used to make panel lighting and frost-free windshields. Stannous fluoride (SnF2) is used in some types of toothpaste