EFFECT OF SODIUM-CHLORIDE SOLUTIONS ON THE STRENGTH AND FATIGUE OF BARE SILICA FIBERS

The strength of bare silica fiber in sodium chloride solutions decreases as the NaCl concentration increases. Static fatigue measurements in deionized water (pH 6) are compared to those in a 2 mM solution of NaCl (pH 5.2), both at 90-degrees-C. The pretransition stress corrosion parameter, determined from the power law, is 33 in deionized water and 18 in the NaCl solution. The effect of NaCl on the reaction mechanism in the pretransition region is investigated. The failure rate is proportional to the surface charge of silica raised to the second power.