EFFECTS OF RADIATION AND HYDROGEN ON THE FRACTURE-RESISTANCE OF BOROSILICATE CLASSES

In this study, short bar fracture toughness samples were used to deter mine the effects of radiation and hydrogen on the resistance to fractu re of vitreous silica and four commercial borosilicate glasses. The re sults showed that neither exposure to 10(10) rads of gamma-radiation n or saturation to a room-temperature-equivalent exposure of 408 atm of hydrogen had an effect on fracture resistance. Nevertheless, when samp les mere saturated with hydrogen and then exposed to radiation, resist ance to fracture increased significantly in some of the glasses. The i ncrease in the resistance to fracture correlated directly with the inc rease in concentration of hydroxyl and hydride groups created by expos ure to radiation and hydrogen. The concentration of these groups diffe rs with glass composition and accounts for the difference in behavior between the types of glass studied.