de Rooij, M.B.

de Vries, E.G.

English

University of Twente Research Information

Kinetic Friction at Cryogenic TemperaturesE.G. de Vries and M.B. de RooijPhone +31-(0)53-3892440, e-mail e.g.devries@ctw.utwente.nlUniversity of Twente, Faculty of Engineering Technology,Section of Surface Technology and Tribology, P.O. Box 217, NL 7500 AE EnschedeCryogenicsCryogenics is the science of producing andstudying low-temperature conditions. Itcomes from the Greek word Cryos,meaning “cold” and the shortened Englishverb “to generate”. It applies totemperatures from approximately -100°Cdown to absolute zero (-273°C = 0K)In the 19th century the development of air-cycle refrigerators to preserve food evolvedinto the liquefaction of permanent gases byscientists. The last element to be liquefiedwas Helium at a boiling point of 4.2 K.The mechanical properties of manymaterials change dramatically when cooledto 100 K or lower. For example plastics andrubber become brittle and metals lose theirelectrical resistance (superconductivity).ApplicationsNew technologies in cryogenic applicationslike superconductors as well as practicalapplications such as transportation,astronomy (see fig.1), metallurgy andmedicine lead to a growing interest inresearch for tribological properties at lowtemperatures.Figure1: Very large telescope interferometer(ESO)These conditions of ultrahigh vacuum (<10-7mbar) and cryogenic temperatures result insome unique tribological problems.At low temperatures liquid lubricants willfreeze or become too viscous. Furthermore,protective oxide layers formed underambient conditions will not be restored.ExperimentsIn order to measure material properties andfriction in a cryogenic environment a frictiontester is developed which makes it possibleto measure friction forces, hardness andadhesion in vacuum at temperatures downto 60 K.Figure 2: Cryogenic-vacuum tribotesterModelThe existing friction models describing therole of adhesion, deformation and shear ofinterfacial layer will be extended to includethe influence of low temperatures andvacuum.References[1] Th.M. Flynn, CryogenicEngineering, Marcel Dekker, 2005.[2] Ye.L.Ostrovskaya, Low temperaturetribology at the B. Verkin Institute forLow temperature Physics &Engineering, Tribology International34, 2001.P-76 Tenth Engineering Mechanics Symposium

Kinetic Friction at Cryogenic Temperatures

https://ris.utwente.nl/ws/files/128785652/DeVries2007kinetic.pdf

Kinetic Friction at Cryogenic Temperatures

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