Greases for Radioactive Environments
What is radiation?
Radiation is energy which can travel in the form of waves or particles. Radiation is commonly grouped into two types- non-ionising radiation and ionising radiation. Radiation, particularly ionising radiation can affect the consistency of lubricants but there is still a need of greases for radioactive environments, such as in nuclear energy, particle accelerators or aerospace industries.
Nuclear energy uses fission (or potentially in the future fusion) to separate or combine atoms and release the energy stored inside the atom. This energy can be harnessed and used to generate electricity. In both space and high-altitude aircraft applications, cosmic rays which are usually mostly filtered out by the Earth’s atmosphere can cause damage to lubricants over time.
What are the best Apiezon greases for radioactive environments?
Manufactured by M&I Materials Ltd, Apiezon L and M greases show a degree of radiation resistance with only a comparatively small increase in stiffness after irradiation with 4 MeV electrons to a level of about 1 MGy.
After this exposure the lubrication properties of the grease are still satisfactory and this is true at even higher levels of irradiation, although the stiffness increases more rapidly. At high levels of irradiation small quantities of gases (mainly methane and ethylene), are evolved so that the grease loses its very low vapour pressure characteristics.