Effect of nickel sulfide inclusions on the spontaneous failure of toughened glasses

Studies have shown that when smaller NiS inclusions are present the “heat-soak” method of rejecting toughened glasses does not completely guarantee that these glasses cannot fail spontaneously while in use. It is posited that the reason why glasses fail spontaneously is not so much the polymorphism of NiS as high stresses around NiS inclusions and, in consequence, a limitation on the “life” time of glass in accordance with the kinetic theory of long-term strength. __________ Translated from Steklo i Keramika, No. 5, pp. 3–6, May, 2007.