Effect of Cure on the Radiation Resistance of Superconducting Magnet Resin Systems
The effect of varying the cure schedule on the cryogenic performance and radiation resistance of a standard liquid epoxy VPI system (CTD-101), a tetrafunctional epoxy prepreg system (CTD-112), a bismaleimide prepreg system (CTD-200) and a HPL polyimide system (CTD-310) has been studied. The resin systems are all suitable for fabricating large superconducting magnets such as the toroidal and poloidal field magnets for ITER.
Shear specimens with S-2 glass fiber reinforcement were fabricated at CTD, and tested at 76 K. Reinforced specimens were then irradiated at ~4 K in the low temperature irradiation facility (TTB) at the 4 MW Munich Research Reactor (FRM) at two dose levels: 2.0 x 107Gy and 1.6 x 108Gy, and at a temperature of ~330 K in the TRIGA Mark II reactor at the Atominstitut in Austria at 2.3 x 108Gy.
For the CTD-101 system, shortening the cure time from 5 h at 110°C with a 16 h postcure at 125°C, to 1.5 h at 135°C without any postcure, does not affect the shear strength, shear modulus or shear strain at cryogenic temperatures.
Regardless of chemical composition, irradiation of an under-cured resin will tend to “cure” the resin, such that it achieves its full 4 K irradiated strength. In no case did the undercured irradiated strength of a material greatly exceed the fully cured irradiated strength.
The paper discusses the effect the cure time and temperature have on the dimensions, mass loss, and mechanical properties at cryogenic temperatures after irradiation.
KeywordsShear Strength Shear Strain Test Temperature Fast Neutron Irradiation Temperature
Unable to display preview. Download preview PDF.
- 2.M. B. Kasen and N. A. Munshi, Cryogenic torsional shear and fracture strength of epoxy and polyimide composites, in “Cryogenic Materials ‘88,” International Cryogenic Materials Conference, Boulder, Colorado (1988).Google Scholar
- 3.H. Gerstenberg, Private Communication (1991).Google Scholar
- 4.H. W. Weber, Private Communication (1989).Google Scholar
- 5.D. Evans and J. T. Morgan, The chemistry of radiation damage in epoxide resins, in “Advances in Cryogenic Engineering, Materials,” Vol. 30, Plenum Press, 1984.Google Scholar
- 6.M.H. Van de Voorde, “Effects of Radiation on Materials and Components,” CERN 70–5, European Organization for Nuclear Research, Geneva (1970).Google Scholar