Boron-free fibers for prevention of acid induced brittle fracture of composite insulator GRP rods

An investigation was performed to determine whether corrosion resistant boron-free E-glass fibers could adequately prevent acid induced brittle fracture failures of high voltage composite insulator rods. Nine different rod compositions were tested at 45% of mechanical failure load in contact with 1 N nitric acid. Rods made out of commonly used E-glass fibers failed mechanically in less than 2 h whereas the rods based on the corrosion resistant boron-free fibers from two different suppliers survived four days of testing with no visible damage to the rods. Differences in resin types had little effect on the times to failure of the rods. Acoustic emission location analysis was also used to determine the location of fiber fractures along the rods. The location analysis revealed significant differences between the rods with the two different types of corrosion resistant fibers. Boron-free fibers with a lower seed (void) concentration exhibited noticeably fewer fiber fractures as measured by acoustic emission in comparison with the high seed boron-free fibers.