Lightweight metal made by melting metals such as copper, or iron alloys, in a sealed furnace filled with hydrogen, or other gas, under pressure. The formation of pores can be controlled by varying pressures and cooling times. They vary in density from 5% to 75% of the metal and in diameter from 5 micrometers (millionths of a meter) to 10 mm/0.39 in. The direction and positioning of the pores can also be controlled.r />
Porous metals were developed in the Ukraine in the 1960s and used in space rockets. Kerosene was forced through the pores to form a fine mist for optimum combustion. The Ukraine remained sole producer, but in 1993 an American aerospace company signed a contract to begin production.
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