Page 54 - Curriculum Visions Dynamic Book

catalytic converter on the exhaust pipe.
Nuclear ceramics
The nuclear power industry has adopted a wide range of ceramics both as part of the fuel and as containers for radioactive waste.
Fuel pellets are made from uranium or plutonium oxide. When the fuel is spent, the radioactive fuel can be immobilized by encasing it in glass, cement, or other stable ceramic material.
Uranium and plutonium oxides are very suitable
as fuel rods, not only because they are radioactive, but also because they melt at very high temperatures and so are stable in the reactor. They are also very resistant to radiation damage.
Pellets are made by crushing uranium ore and then pressing it into shape before sintering it at very high temperature (1,700°C).
Making ceramics for nuclear applications is much harder than it is for most other industries because the reactors work at very high temperatures, many of the liquids are corrosive, and the material is constantly being bombarded with radioactivity.
Bioceramics
Ceramics have many advantages for medical purposes; when they are used in this way, they are referred to as bioceramics.
Surgeons and those fitting artificial limbs and dentures often need materials that are hard, that are strong especially when pulled or crushed, and that will not crack (suffer from fatigue) or easily chip. Materials also have to stand up to long-term wear; they must
not shrink or swell much with temperature or when
in liquids. Materials must not let liquids, gases, or life molecules in or out, and they must not corrode when constantly surrounded by the body’s fluids. At the same time, the materials must not cause allergic reactions or be toxic to the body. These are tougher demands than for any other kind of use.
(Below) Ceramics containing radioactive materials are used as fuel rods in reactors.
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