What material is best for centrifuge rotors?

Release time:

2014-05-22

Overview:

Aluminum alloys, titanium alloys, and carbon-fiber-reinforced plastics have already been used in rotor manufacturing. Among these, carbon-fiber-reinforced plastics are now commonly referred to as carbon-fiber composites. Glass-fiber-reinforced plastics, however, have not yet been employed. Martensitic steels are used in the manufacture of gas centrifuge rotors, such as those found in ultracentrifuges used for uranium enrichment.

Rotors for low-speed centrifuges are typically made from stainless steel, ordinary steel, or even engineering plastics; whereas high-speed and ultrahigh-speed rotors are often fabricated from alloys such as aluminum alloys and titanium alloys. The mechanical stress acting on the rotor is proportional to the square of the rotational speed—thus, the higher the rotational speed, the greater the stress experienced by the rotor. Moreover, this stress is a centrifugal stress, which is a body force that is directly proportional to the material’s density. Therefore, centrifuge rotors should be made from materials with a high specific strength (strength-to-density ratio)—and for convenience in dimensional calculations, we still use density here. Materials with high specific strength primarily include aluminum alloys, titanium alloys, and carbon fiber.

Aluminum alloys, titanium alloys, and carbon-fiber-reinforced plastics have already been used in rotor manufacturing. Among these, carbon-fiber-reinforced plastics are now commonly referred to as carbon-fiber composites. Glass-fiber-reinforced plastics, however, have not yet been employed. Martensitic steels, on the other hand, are used in the manufacture of gas centrifuge rotors, such as those found in ultracentrifuges used for uranium enrichment.

Since the maximum allowable speeds and capacities of different rotors vary considerably, and taking into account the cost of rotor manufacturing, low-speed centrifuge rotors operating below 5,000 r/min are generally made from ordinary steel, stainless steel, and engineering plastics. High-speed centrifuge rotors—ranging from 5,000 to 50,000 r/min—and some ultrahigh-speed centrifuge rotors are often made from aluminum alloys. For speeds exceeding 50,000 r/min, titanium alloys are predominantly used. In recent years, carbon-fiber composite materials have also been employed in rotor manufacturing, though rotors made from these materials remain relatively few in number and are quite expensive.

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