Mechanical Properties and Strain Effects in Bi2Sr2CaCu2Ox/Ag Composite Conductors
With the development and testing of powder-in-tube and surface-coated Bi2Sr2CaCu2Ox (Bi2212) prototype systems to demonstrate engineering feasibility there is a need for accurate engineering data on the superconducting materials. Another important issue is the effect of mechanical strain on the superconducting properties. While it is evident that large strains induce irreversible damage, applications may be limited by fatigue at low strain values due to crack propagation. Here we report on the mechanical properties at room temperature and both the mechanical and superconducting properties at liquid helium temperature of IGC surface-coated Bi2212 conductor. Results of the effects of cyclic fatigue on Jc of the Bi2212 as measured by electrical transport are also shown. The conductor’s critical current exhibited little sensitivity to strain below a critical strain of 0.165% in room temperature axial strain tests. Above the critical strain little critical current remained. The effect on Ic was the same regardless of the number of times the conductor was cycled at a given strain. Tests performed at 4.2K in a Lorentz-force axial strain device showed a gradual degradation in Ic above a critical strain of 0.18%. Room temperature bend strain results can be explained by a simple application of the axial room temperature Ic versus s result.
KeywordsCritical Current Critical Strain Superconducting Property Liquid Helium Temperature Gradual Degradation
Unable to display preview. Download preview PDF.
- 2.D.K. Hilton, H.W. Weijers, Y.S. Hascicek, S.W. Van Sciver, and J. Schwartz, Lorentz-Force Tensile Stress-Strain and Fatigue Apparatus, Rev. Sci. Instr., Submitted 1997Google Scholar
- 4.Marks’ Standard Handbook for Mechanical Engineers“, 9th edition, E.A. Avallone and T. Baumeister, ed., McGraw-Hill Book Company, New York (1978).Google Scholar
- 5.J. McKeown and O. Hudson, J. Inst. Met., 60: (1937)Google Scholar