Friction materials operating under high stress, cryogenic temperature, and in vacuum

• Autorzy: Piec Z. , Nowacki J.
• Języki publikacji: EN

Abstrakty

EN

Purpose: of this paper was to select interfacial materials to provide friction coefficients less than μ= 0.3 which remain at this level during the machine lifetime. This material must withstand cycling motion under pressures up to 80 MPa, at 77 K, and in vacuum of 10-4 Pa. Design/methodology/approach: In the described work, experiments were conducted to determine the friction coefficient and the wear of several low friction materials. The test rig consists of a cryogenic sample holder enclosed in vacuum chamber installed into a servo-hydraulic test machine (M.T.S.). The friction coefficients have been measured cycling the samples (1,960 mm2) for about 38,000 cycles at normal pressure up to 80 MPa, sliding speed of 0.1 m/min, at 77 K, and under vacuum of 10-4 Pa. Findings: The Fiberslip B40 (woven multifilament of PTFE and glass) was selected as the best candidate material. It exhibited a friction coefficient of approximately μ = 0.22, and low wear rate was obtained. The maximum value of the friction coefficient is reached after few thousand cycles and then remains fairly constant. Research limitations/implications: Further studies on relative sliding/sticking at magnets interfaces as well as predicting the heating due to frictional forces are required. Practical implications: application of the selected material is possible in large friction interfaces operating under high compression stress, cryogenic temperature, and in vacuum one can meet in nuclear power stations. Originality/value: The experimental program verified the testing methodology, and techniques selected for measurement of coefficient of friction and wear for the friction pairs with large contact area, which are operated at temperature of 77 K, under high contact pressure and in vacuum.

Słowa kluczowe

EN

composites; wear resistance; metallography; materials design; quality assessment

PL

kompozyty; odporność na zużycie; metalografia; projektowanie materiałów; ocena jakości

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2006
• Tom: Vol. 18, nr 1-2
• Strony: 15--24
• Opis fizyczny: Bibliogr. 12 poz., rys., tab., wykr.

Twórcy

autor

Piec Z.

• Massachusetts Institute of Technology-Plasma Science and Fusion Center M.I.T. Cambridge MA 02139, USA

autor

Nowacki J.

• Institute of Materials Science and Engineering, Szczecin University of Technology, Al. Piastow 19, 70–310 Szczecin, Poland

Bibliografia

• [1] P.C. Michael, E. Rabinowicz, Y Iwasa: “Friction and Wear of Polymeric Materials at 293, 77 and 4.2 K”, Cryogenics, Vol. 31, (1991), 695.
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• [3] L.F. Moreschi, S. Satori, A. Pizzuto, Z. Piec, G. Malavasi: “ITER magnetic system candidates low friction materials tested under vacuum at cryogenic temperature” Symposium on Fusion technology 20, Marseille France, (1998), Conf. Proceedings, 99.
• [4] L.F. Moreschi, S. Satori et al.: ”Low friction test for ITER magnets”, ITER Task M. 49 Document MF-A-R-002, 31.05.
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• [7] Z. Piec, J. Nowacki: “Evaluation of Low Friction Composite Materials at Cryogenic Temperature under High Contact Pressure and Vacuum”, International Scientific Conference „Achivements in Mechanical & Materials Engineering” Polish Academy of Science - Silesian Technical University, Rydzyna 1999, Conf. Proceedings, 478.
• [8] Z. Piec, PhD Thesis: “Friction and wear at cryogenic temperatures, under high compression stress, and in vacuum on example of friction interfaces of the thermonuclear reactor”, Technical University of Szczecin, Department of Mechanical Engineering, 2000.
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