Ideally the value for E
f
should be determined experimentally for a new coatings
or for coatings with unknown properties.
14.6 USE AND HANDLING OF CARBON-COATED
HERMETIC FIBERS
Carbon-coated fibers can be worked with in much the same way as standard
nonhermetic fibers. However, there are a few differences, as discussed in the
following section.
14.6.1 Fiber Strength
As mentioned earlier, the fracture strengths of carbon-coated fibers are lower
than those of standard nonhermetic fibers. The root cause of the strength
reduction is at least partially understood [11, 22], and it is reasonably clear
that some tradeoff in fiber strength is necessary to achieve improved hermetic
properties, especially with respect to hydrogen diffusion. Nonetheless, fibers with ...