Resistance to stress corrosion cracking of unidirectional ECR-glass/polymer composites for high voltage composite insulator applications

Stress corrosion experiments were performed on unidirectional ECR-glass/polymer composites with the modified polyester, epoxy and vinyl ester resins for the use in high voltage composite insulator applications. Two types of ECR-glass fibers were investigated with low and high counts of gaseous inclusions (seeds) within the glass. The stress corrosion tests were performed in nitric acid under four point bending conditions and the resistance to stress corrosion cracking (SCC) of the composites was determined for as-supplied and sandblasted surface conditions. In addition, the materials were analyzed for their micro-hardness and surface fiber exposure. The resistance to SCC of the ECR-glass/polymer composites was compared with that of the E-glass/polymer systems. It has been found that the ECR-glass fiber composites vastly out-perform their E-glass counterparts regarding their resistance to SCC in nitric acid. The stress corrosion data presented in this work should help composite insulator manufacturers in the selection of composite rod materials with substantially increased resistance to SCC to lower the number of brittle fracture failures among their products.